9th international conference on fibre-reinforced polymer ... · dawood mina de lorenzis laura...

2

2018

Edited by :

FERRIER Emmanuel

BENZARTI Karim

CARON Jean-François

9th International Conference on Fibre-Reinforced Polymer (FRP)

Composites in Civil Engineering (CICE 2018),

PARIS 17-19 JULY 2018

Abstracts

9th International Conference on Fibre-Reinforced Polymer (FRP) Composites

in Civil Engineering (CICE 2018), PARIS 17-19 JULY 2018

July 17-19, 2018Paris

A warm welcome to Paris for CICE 2018 !

Fiber Reinforced Polymers (FRP) composites have emerged over the past two decades as practical materials for

civil engineering applications. The wide utilization of FRPs has increased significantly in recent years offering us

new ways, both for strengthening of existing structures and for new construction. The rapid increase in the use of

FRP composites in civil engineering can be attributed to continuing reductions in material costs, more

comprehensive knowledge of the fundamental properties of composites, which has enabled more realistic reduced

safety factors, and to the numerous advantages of FRPs as compared with conventional materials such as concrete

and steel.

The CICE conference series (International Conference on FRP Composites in Civil Engineering) started in 2001

in Hong Kong and became the official conference series of the International Institute for FRP in Construction,

IIFC (www.iifc-hq.org) in 2003. Since then, this major event in the field of FRPs has travelled around the world,

with stopovers in Australia (Adelaide 2004), USA (Miami 2006), Switzerland (Zurich 2008), China (Beijing 2010

and Hong-Kong 2016), Italy (Rome 2012) and Canada (Vancouver 2014).

It is a great privilege to host CICE in France this year, in the beautiful city of Paris. The conference is co-organized

by IFSTTAR (French Institute of Science and Technology for Transport, Development and Networks), Ecole des

Ponts ParisTech and University Claude Bernard LYON 1, and it is hosted at the campus of Paris-Est University

in Marne-la-Vallée.

The scientific program of CICE 2018 includes a total of 288 papers from some 40 countries. It has been tailored

to reflect the wide spectrum of topics shared by the scientific community, with an emphasis on advanced research

and future trends related to FRP strengthening and structural applications, which constitutes the highlight of the

CICE conference series. Besides, the program encompasses other hot topics, such as new materials like fiber

reinforced cementitious matrix (FRCM) composites or bio-based composites, or more practical issues related to

field applications and design guidelines.

We are very confident that CICE 2018, like previous conferences, will provide an international forum where

researchers, civil engineers, practitioners and industrial partners will have the opportunity to share their latest

advances and open new perspectives for future collaborative projects.

Alongside this enriching technical program, exciting social events will bring a “French touch” to the conference.

Delegates and their accompanying persons will enjoy a refreshing cocktail at the first floor of the Eiffel Tower

during the welcome reception, and the conference dinner cruise over the river Seine will offer the possibility to

taste a gourmet menu while admiring some of the most beautiful monuments of Paris.

Finally, the co-chairs would like to warmly thank all the persons which were involved in the conference

organization. First, we are very thankful to all authors who have contributed to the conference by submitting high

quality papers. Special thanks are then expressed to the members of the International Scientific Committee who

carefully reviewed the papers, and whose input and advice were highly valuable. We are also very grateful to the

members of the local organization committee, academic staff and students, who donated their time and contributed

to the success of CICE 2018.

The support from the exhibitors and the industrial/institutional sponsors is of course acknowledged and highly

appreciated.

We do not forget to acknowledge our academic institutions, IFSTTAR, Ecole des Ponts ParisTech and University

Lyon1 (Cellule Congrès) for providing assistance and conference facilities.

http://www.iifc-hq.org/




The 9 th International Conference on Fibre-Reinforced Polymer (FRP Composites in Civil Engineering (CICE

2018) have been financially support by several companies and institute.

Their support makes our events extra special for attendees. We appreciate their interest in IIFC’s vision and are

grateful for their support. CICE 2018 Conference wouldn't be possible without the support of our sponsors.

https://www.google.fr/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiW-4qO_f_bAhVLbhQKHYDSCZQQjRx6BAgBEAU&url=https://scienceoxford.com/business/instron/&psig=AOvVaw1qJDw2oGOTrfwoKJGY-W1F&ust=1530605805869962

Conference Co-Chairs:

Emmanuel FERRIER

Professor at Lyon 1 University

Laboratory of Composite Materials for Construction

Karim BENZARTI

Senior Researcher at IFSTTAR

Department for Materials & Structures

Jean-François CARON

Senior Researcher and Professor

Ecole des Ponts ParisTech.

Local organizing Committee :

Laurent Michel, Associate Professor (Université Lyon 1),

Marc Quiertant, Senior Researchers (IFSTTAR),

Gilles Foret, Professor (Ecole des Ponts ParisTech),

Arthur Lebée and Loannis Stéfanou, Researchers (Ecole des Ponts ParisTech)

Sylvain Chataigner, Researcher (IFSTTAR)

Amen Agbossou, Université Savoie

Monssef Drissi Habti, IFSTTAR

International Scientific Committee:

AL-MAHAIDI Riadh ARAVINTHAN Thiru BAI Yu .

BAKIS Charles E BANK Lawrence C. BENMOKRANE Brahim

BENZARTI Karim BISBY Luke BUDELMANN Harald

BURGOYNE Chris BUYUKOZTURK Oral CAI Steve C.S.

CARON Jean François CASAS Joan R. CHEN Guang-Ming

CHEN Jian-Fei CHENG Li-Juan CORREIA J. R.

DA SILVA Manuel DAI Jian-Guo DARBY Antony

DAWOOD Mina DE LORENZIS Laura DRISSI HABTI Monssef

EID Rami EI-HACHA Raafat FAM Amir

FENG Peng FERNANDO D. FERRIER Emmanuel

FOSTER Stephen FRANCOIS Raoul G. GENTRY Russell

GRACE Nabil F. GREEN Mark F GREMAL Hughes

GRIFFITH Michael GUADAGNINI Maurizio HARIK Issam E.

HARRIES Kent A. IBELL Tim ILKI Alper

KANAKUBO Toshiyuki KARBHARI Vistasp M. KELLER Thomas

KIM Jimmy KODUR Venkatesh KOTYNIA Renata

LAM Lik LEES Janet LEUNG Christopher K.Y.

LI Hui LI Li-Juan LI Rong

LIU Wei-Qing LOPEZ Maria LU Yi-Yan

MA Zhongguo John MATSUMOTO T. MATTA Fabio

MEIER Urs MIRMIRAN Amir MONTI Giorgio

MOSALAM Khalid M. MOTAVALLI Masoud NANNI Antonio

OZBAKKALOGLU T. PARK Younghwan PELLEGRINO Carlo

PULIDO, M Dolores RABINOVITCH Oded RIZKALLA Sami H.

RTEIL Ahmad SAVOIA Marco SCHMIDT Jacob W.

SENA-CRUZ José SERACINO Rudolf SHEIKH Shamim A.

SMITH Scott T. STRATFORD Tim TAN Kiang Hwee

TAYLOR Susan TENG Jin-Guang TRIANTAFILLOU T.C.

UEDA Tamon WAN Bao-Lin WANG Jia-Lai

WANG Xin WANG Yuan-Feng WU Gang

WU Yu-Fei WU Zhi-Shen XIAN Gui-Jun

XIAO Yan XUE Wei-Chen YANG Yong-Xin

YAO Jian YE Lie-Ping YU Tao

YUE Qing-Rui ZHAO Xiao-Ling ZHOU Li Min

TABLE OF CONTENT

Keynotes ....................................................................................................................................................... 22

TECHNICAL SPECIFICITIES WHEN DESIGNING WITH COMPOSITE MATERIALS – CASE OF

BUILDING AND ARCHITECTURE .................................................................................................................. 23

Samuel Durand1

DEVELOPMENT OF UK GUIDANCE FOR DESIGNERS OF FRP BRIDGES ............................................... 25

N.Farmer

OPPORTUNITIES FOR RECYCLING AND REUSE OF FRP COMPOSITES FOR CONSTRUCTION IN A

CIRCULAR ECONOMY ..................................................................................................................................... 26

Lawrence C. Bank

RECENT DEVELOPMENTS ON FRP REBARS AS INTERNAL REINFORCEMENT IN CONCRETE

STRUCTURES AND FIELD APPLICATIONS .................................................................................................. 27

Brahim Benmokrane1 and Hamdy M. Mohamed2

HYBRID FRP-CONCRETE-STEEL TUBULAR MEMBERS............................................................................ 28

Tao Yu

STRUCTURAL BEHAVIOR OF FRP-REINFORCED GEOPOLYMER CONCRETE SANDWICH WALL

PANELS FOR PREFABRICATED CONSTRUCTION ...................................................................................... 29

Jian-Guo DAI* and Jun-Qi HUANG

Composite Material ........................................................................................................................... 30

SHEAR TESTING OF DIFFERENT TYPE AND SIZE OF GFRP REINFORCING BARS .............................. 31

A.S. Genikomsou 1, G.P. Balomenos 2 and M.A. Polak 3

SALT WATER AND ALKALINE ATTACK ON GFRP REBARS .................................................................... 32

Miguel M. Estêvão1, Manuel A. G. Silva2 , Fernando F. S. Pinho3

EFFECTS OF FIBER ARCHITECTURE ON FLEXURE PROPERTIES OF PULTRUDED GFRP PLATES AND

SECTIONS ........................................................................................................................................................... 33

Tianqiao Liu1, Kent A. Harries1,2 and Qi Guo1

FATIGUE AND DURABILITY OF LAMINATED CARBON FIBRE REINFORCED POLYMER STRAPS FOR

BRIDGE SUSPENDERS ...................................................................................................................................... 34

Fabio Baschnagel1, Giovanni Pietro Terrasi1, Zafiris Triantafyllidis2, Urs Meier 3

GLASS–GFRP HYBRIDS: FROM BRITTLE GLASS TO DUCTILE AND HIGH STRENGTH STRUCTURAL

GLASS .................................................................................................................................................................. 35

Mithila Achintha 1*, Bogdan Balan 1, Mikhail Bessonov 1, Tudor Zirbo 1, Jesmer Kanvar 1

INFLUENCE OF CURING CONDITIONS ON THE MECHANICAL BEHAVIOR OF GLUED JOINTS OF

CARBON FIBER REINFORCED POLYMER COMPOSITE / CONCRETE .................................................... 36

Anh Tuan LEE1, Marie MICHEL1, Emmanuel FERRIER 1

BEHAVIOR OF CFRP STRANDS EXPOSED TO SEVERE ENVIRONMENTAL CONDITIONS ................ 37

Omar Khalafalla 1, Sami Rizkalla 1, Adel ElSafty 2, Mohammad Pour-Ghaz 1

INCREASING THE MECHANICAL EFFICIENCY OF PIN-LOADED STRAPS USING THE SLING

ANCHORAGE METHOD.................................................................................................................................... 38

Bernd Zwingmann1, Yue Liu 2, Mike Schlaich 2, Steffen Janetzko 3

EFFECT OF INTERNAL MOISTURE CONTENT ON THE TG VALUES OF CFRP RODS .......................... 39

Eleni Toumpanaki1, Janet M. Lees2, Michel Barbezat3 and Giovanni P. Terrasi4

EVOLUTION OF THE TENSILE RESPONSE OF UNIDIRECTIONAL HYBRID FRP LAMINATES

FABRICATED BY HAND LAY-UP METHOD: EXPERIMENTAL AND ANALYTIC ASSESSMENT ....... 40

Filipe Ribeiro1, José Sena-Cruz 2, Eduardo Júlio 1, Fernando Branco 3, Fernando Castro 4

NOVEL CAPACITIVE CFRP SENSOR FOR STRUCTURAL HEALTH MONITORING .............................. 42

J. Yan 1, S. Hassan 1, A. Chen 1 and S. Laflamme 1

EMBEDDED PIEZO MICRO-PATCHES FOR CURE MONITORING OF FIBER-REINFORCED EPOXY IN

CIVIL ENGINEERING REPAIRS ....................................................................................................................... 43

Olivier Bareille1, Michelle Salvia 1, Fernanda Benezra-Maia 2

DYNAMIC TENSILE PROPERTIES OF POLYETHYLENE TEREPHTHALATE FIBER BUNDLE WITH

LARGE DEFORMABILITY ................................................................................................................................ 44

Y.L. Bai 1, Z.W Yan 1, J. G. Dai 2, D. J. Zhu 3, Q Han 1, X.L. Du 1

INTERFACIAL ADHESION STUDY ON EPOXY PREPREG MODIFIED WITH HIGH POLY(CARBONATE)

LOADING ............................................................................................................................................................ 45

Utai Meekum* and Waree Wangkheeree

TWO-DIMENSIONAL DELAMINATION IN GFRP LAMINATES: EXPERIMENTAL INVESTIGATION . 46

Aida Cameselle-Molares1, Anastasios Vassilopoulos1, Thomas Keller 1

RELAXATION OF FRP MATERIALS – ISSUE OVERVIEW IN THE AVAILABLE LITERATURE, CODES

AND GUIDELINES ............................................................................................................................................. 48

Marta Przygocka1, Renata Kotynia 1

BEHAVIOR OF GFRP BARS IN SEAWATER-CONTAMINATED CONCRETE SUBJECTED TO

SUSTAINED LOADING ..................................................................................................................................... 49

Hilal El-Hassan1, Tamer El-Maaddawy1, Abdelrahman Al-Sallamin1

ENVIRONMENTAL DURABILITY OF HAND-LAYUP CARBON/EPOXY COMPOSITES INTENDED FOR

STRENGTHENING OF CONCRETE STRUCTURES ....................................................................................... 50

Wendlamita Zombré1, Robert Chlela2, Marie Michel1, Julien Mercier3, Karim Benzarti2, Laurence Curtil1

ASTM SPECIFICATION FOR GLASS-FIBER REINFORCED POLYMER BARS FOR CONCRETE

REINFORCEMENT ............................................................................................................................................. 51

R. Gentry 1 and C. E. Bakis 2

PREDICTION OF TENSILE STRENGTH OF FRP CABLE CONSIDERING RANDOM STRENGTH

DISTRIBUTION ................................................................................................................................................... 52

Z. Q. Peng1, L. N. Ding2, X. Wang1 and Z. S. Wu1

Eco composite or bio sourced composites materials ......................................... 53

FATIGUE PERFORMANCE OF BIORESIN GLASS FIBRE REINFORCED POLYMERS ............................ 54

A. Watfa 1, M. F. Green 2 and A. Fam 2

ILLUMINATED BIOBASED SANDWICH FACADE WITH NATURAL FIBRE REINFORCED POLYMER

AND CARDBOARD CORE ................................................................................................................................ 55

Carolin Petzoldt1, Ralf Gliniorz1, Andreas Ehrlich1, Sandra Gelbrich1, Lothar Kroll1

EFFECTS OF CNF CONTENT ON MECHANICAL PROPERTIES OF FLAX FIBER REINFORCED

NANOCOMPOSITES .......................................................................................................................................... 56

Yanlei Wang1, Baolin Wan2, Xiushui Yin3

BIOBASED EPOXY NETWORKS FOR CIVIL ENGINEERING APPLICATIONS ........................................ 57

J. Galy, A. Viretto

PHYSICAL AND MECHANICAL CHARACTERIZATION OF NATURAL FIBERS AND FABRICS AS

REINFORCEMENT FOR COMPOSITE SYSTEMS .......................................................................................... 58

Giuseppe Ferrara1, Bartolomeo Coppola 2, Luciano Di Maio 2, Enzo Martinelli1

EMPIRICAL DESIGN EQUATION TO PREDICT THE AXIAL LOAD CAPACITY OF SANDWICH PANELS

WITH FLAX FRP SKINS .................................................................................................................................... 59

M. Noël 1 and A. Fam 2

HYGROTHERMAL AGEING OF FLAX FIBRE REINFORCED COMPOSITES INTENDED FOR THE

STRENGTHENING OF CONCRETE STRUCTURES ....................................................................................... 60

R. Chlela 1, W. Zombré 2, M. Quiertant 3, L. Curtil 2, and K. Benzarti 1

BASALT FIBER REINFORCED POLYMER (BFRP): AN INNOVATIVE COMPOSITE TO REPAIR

CONCRETE STRUCTURES? ............................................................................................................................. 61

Clément Lacoste1, Anne Bergeret 1

FRC and cement based composite materials ......................................................................................................... 62

STRAIN AND CRACK DETECTION IN EXPERIMENTAL TESTS ON TEXTILE REINFORCED MORTAR

COMPOSITES ...................................................................................................................................................... 63

Marcin Tekieli1*, Stefano De Santis2, Gianmarco de Felice2, Łukasz Hojdys1, Piotr Krajewski1, Arkadiusz

Kwiecień1, Francesca Roscini2

MECHANICAL CHARACTERIZATION OF MULTI-PLY STEEL REINFORCED GROUT COMPOSITES

FOR THE STRENGTHENING OF CONCRETE STRUCTURES ...................................................................... 64

Georgia E. Thermou1,2, Gianmarco de Felice3, Stefano De Santis3, Sultan Alotaibi1, Francesca Roscini3, Iman

Hajirasouliha1, Maurizio Guadagnini1

DURABILITY OF TEXTILE REINFORCED MORTAR (TRM) SYSTEMS .................................................... 65

Francesca Giulia Carozzi1, Pierluigi Colombi1, Tommaso D’Antino1, Carlo Poggi1

STUDY OF THE MATRIX-FIBER BOND BEHAVIOR OF CARBON AND GLASS FRCM COMPOSITES 66

Lesley H. Sneed1, Tommaso D’Antino2, J.H. Gonzalez-Libreros3, Christian Carloni4, Carlo Pellegrino3

NUMERICAL ANALYSIS OF PBO FRCM-CONCRETE JOINTS ................................................................... 67

Tommaso D’Antino1, Lesley H. Sneed2, Christian Carloni3, Carlo Pellegrino4

BOND BEHAVIOR OF BASALT TEXTILE GRID IN UHDCC ....................................................................... 68

Jiafei Jiang 1,2, Xiangxiang Dou 1, Jiangtao Yu 1, Haibei Xiong 1

A MULTISCALE APPROACH FOR TEXTILE REINFORCED CONCRETE: ILLUSTRATION ON TRC

SANDWICH PANELS ......................................................................................................................................... 69

Zakaria.Ilyes .Djamai1, Ferdinando .Salvatore1, Amir.Si Larbi1, Mohamed.El Mankibi2

INFLUENCE OF PRE-IMPREGNATION PROCESS ON MECHANICAL PERFORMANCE OF

GLASS/ETTRINGITIC MATRIX COMPOSITE ................................................................................................ 70

Omayma HOMORO, Marie MICHEL, Emma LANOYE, Thouraya N. BARANGER

APPLICATION OF A TRILINEAR BOND-SLIP MODEL TO FRCM-CONCRETE JOINTS ......................... 71

Xingxing Zou1, Lesley Sneed 1, Tommaso D’Antino 2, Christian Carloni 3

SINGLE FIBRE-TO-MORTAR BOND CHARACTERIZATION IN TRM COMPOSITES ............................. 72

Bahman Ghiassi1, Ali Dalalbashi2, Daniel V. Oliveira2

Bond ................................................................................................................................................................ 73

MODE II INTERFACE CONSTITUTIVE LAW FOR CONCRETE SUBSTRATES STRENGTHENED WITH

STEEL REINFORCE POLYMERS ..................................................................................................................... 74

Francesco Ascione1, Marco Lamberti 1, Annalisa Napoli 1, Ghani Razaqpur 2 , Roberto Realfonzo1

FRP-TO-CONCRETE DEBONDING - GLOBAL AND LOCAL BOND BEHAVIOUR .................................. 75

M. Breveglieri 1*, A. Hosseini 1,2 and C. Czaderski 1

BOND BEHAVIOR OF PRE-CURED CFRP STRIPS TO CONCRETE USING EXTERNALLY BONDED

REINFORCEMENT ON GROOVE (EBROG) METHOD .................................................................................. 76

Niloufar Moshiri 1,2, Davood Mostofinejad 1, Amir Tajmir-Riahi 1

BOND RESISTANCE OF A SINGLE GROOVE IN EBROG METHOD TO ATTACH CFRP SHEETS ON

CONCRETE ......................................................................................................................................................... 77

Amir Tajmir-Riahi 1, Davood Mostofinejad 1, Niloufar Moshiri 1,2

WIDTH EFFECT OF INTERFACIAL BOND ..................................................................................................... 78

Yu-Fei Wu 1, Jian-Ping Lin 2, Liang He 3

THE BOND BEHAVIOR OF SRP-TO-CONCRETE SYSTEM IN FIELD ENVIRONMENT .......................... 79

Wei Wang 1, and John J. Myers 2

FLEXURAL STRENGTHENING OF RC BEAMS USING SIDE NSM CFRP BARS: AN EXPERIMENTAL

INVESTIGATION ................................................................................................................................................ 81

Thanongsak Imjai 1, Udomvit Chaisakulkiet 2 and Reyes Garcia 3

ANALYSES ON THE BOND TRANSFER BETWEEN FRP COMPOSITES AND OTHER STRUCTURAL

MATERIALS ........................................................................................................................................................ 82

Hugo Biscaia1, Carlos Chastre2, João Cardoso3, Noel Franco4

COHESIVE ZONE MODELLING OF A PRESTRESSED NON-MECHANICAL CFRP ANCHORAGE

SUBJECTED TO FREEZE-THAW CYCLES ..................................................................................................... 83

Yunus Emre Harmanci1,2, Edmunds Zile3, Julien Michels 4, Eleni Chatzi 1

ATOMISTIC INVESTIGATION ON INTERFACIAL DETERIORATION OF EPOXY-BONDED INTERFACE

UNDER HYGROTHERMAL ENVIRONMENT ................................................................................................ 84

Chao Wu, Ruidong Wu, Lik-ho Tam *

EXPERIMENTAL STUDY OF CFRP-TO-CONCRETE BONDED JOINTS UNDER FATIGUE LOADING . 85

Hao Zhou, Van Thuan Nguyen, Dilum Fernando

INFLUENCE OF VARIOUS PROCESS PARAMETERS ON THE MECHANICAL PERFORMANCE OF

CFRP/CONCRETE ADHESIVE BOND .............................................................................................................. 86

Karim Benzarti1, Nicolas Roche2, Corentin Le Roy3, Jeremy Roth3, André Flety3, Christophe Aubagnac3

Composites structures ..................................................................................................................... 87

LONG-TIME BEHAVIOUR OF GFRP/CONCRETE HYBRID STRUCTURES .............................................. 88

Ibrahim Alachek1, Nadège Reboul1, Bruno Jurkiewiez 1

THE BEHAVIOUR OF DUCTILE LINK SLAB DESIGNED WITH FRP REINFORCED ECC ...................... 89

Yu Zheng1, Lipeng Xia1, Lifei Zhang1 and Jianbin Yang1

AXIAL COMPRESSIVE BEHAVIOUR OF COMPOSITE TUBES WITH DIFFERENT GROUT INFILLS .. 90

Ali A. Mohammed1,2, Allan C. Manalo1, Ginghis B. Maranan1, Yan Zhuge 1

AXIAL COMPRESSION – BENDING INTERACTION OF HYBRID FRP STRENGTHENED RC COLUMN

ELEMENTS .......................................................................................................................................................... 92

Chellapandian M1, Suriya Prakash S2, Akanshu Sharma3

EXPERIMENTAL AND ANALYTICAL STUDY OF GFRP AND UFC COMPOSITE BEAMS .................... 93

Isuru Sanjaya Kumara Wijayawardane1, Hiroshi Mutsuyoshi2

FLEXURAL BEHAVIOUR OF AN INNOVATIVE CONNECTION FOR STRUCTURAL SANDWICH

PANELS ............................................................................................................................................................... 94

R. Lameiras 1, J. Barros2, I.B. Valente2 and M. Azenha2

BEHAVIOUR OF CONCRETE SANDWICH WALL PANELS IN FLEXURE USING A NOVEL GFRP SHEAR

CONNECTOR ...................................................................................................................................................... 95

Debrup Dutta1, Amir Fam2

HOW MUCH DAMAGE CAN FRP TUBE TOLERATE IN CFFT? .................................................................. 96

Chenxi Lu 1, James St. Onge 2 and Amir Fam 3

DOUBLY-CURVED SANDWICH PANELS WITH UHPC-FACINGS ............................................................. 97

Alexander Stark1, Christian Knorrek1, Sophia Perse1

LARGE-SCALE SLENDER HYBRID FRP-CONCRETE-STEEL DOUBLE SKIN TUBULAR COLUMNS

SUBJECTED TO ECCENTRIC COMPRESSION .............................................................................................. 98

P. Xie1,2, T. Jiang3 and J.G. Teng2,*

EXPERIMENTAL INVESTIGATION OF A NEW PRECAST BEAM-COLUMN CONNECTION FOR

CONCRETE-FILLED FRP TUBES (CFFTS) ...................................................................................................... 99

Ahmed M. Ali 1, Radhouane Masmoudi 2

MOMENT-CURVATURE CHARACTERISTIC OF STEEL AND CFRP REINFORCED CFFT COLUMNS:

EXPERIMENTAL AND THEORETICAL STUDY .......................................................................................... 100

Maha Hussein Abdallah1, Hamdy M. Mohamed2, Radhouane Masmoudi3, Ahmed Moussa4

BEHAVIOR OF GFRP WALL PANEL WITH INTERNAL TUNED LIQUID COLUMN DAMPER ............ 101

H. Wu 1, A. Chen 2 and S. Laflamme 3

Timber and FRP ................................................................................................................................ 102

MECHANICAL BEHAVIOR OF HYBRIDAL FLOOR PANELS TO TIMBER COLUMNS JOINTS .......... 103

Magdalini Titirla 1, Laurent Michel 1, Emmanuel Ferrier 1

BOND ANALYSIS OF BASALT FIBRE REINFORCED POLYMER (BFRP) BARS AND TIMBER BEAMS

UNDER AXIAL LOADING .............................................................................................................................. 104

D. Walline 1 and A. Rteil 2

COMPRESSIVE BEHAVIOR OF MEDIUM STRENGTH CIRCULAR GLUE LAMINATED TIMBER

COLUMNS JACKETED WITH FRP SHEETS ................................................................................................. 105

Omer Asim SISMAN1, Ali ISIKARA2, Ergun BINBIR3 and Alper ILKI4

WIDTH EFFECT OF FRP EXTERNALLY BONDED TO TIMBER ............................................................... 106

Abbas Vahedian1, Dr Rijun Shrestha1, Prof Keith Crews1

All FRP Structures .......................................................................................................................... 107

EXPERIMENTAL INVESTIGATION ON FLANGE LOCAL BUCKLING OF PULTRUDED GFRP BOX-

SECTION UNDER FLEXURE .......................................................................................................................... 108

Tianqiao Liu1 and Kent A. Harries1,2

LONG-TERM DESIGN OF GFRP-PUR WEB-CORE SANDWICH STRUCTURES ..................................... 109

Sonia Yanes-Armas1, Julia de Castro1, Thomas Keller1

MULTI-OBJECTIVE OPTIMIZATION OF A COMPOSITE SANDWICH PANEL FLOOR SYSTEM FOR

BUILDING REHABILITATION ....................................................................................................................... 111

Mário Garrido1, José F.A. Madeira2,3, Miguel Proença1, João R. Correia1

DEVELOPMENT OF A SNAP-FIT CONNECTION SYSTEM BETWEEN PULTRUDED GFRP SANDWICH

PANELS FOR BUILDING FLOORS ................................................................................................................ 112

Miguel Proença1, Mário Garrido1, João R. Correia1

FORM-FINDING AND STRUCTURAL DESIGN OF AN ARCHITECTURAL SCENERY WITH ALL GFRP

FREE-FORM FACADE ..................................................................................................................................... 113

Yuchao ZHAO1, Xu JIANG 1, Qilin ZHANG 1, Qi WANG 1

MONOTONIC AND CYCLIC BEHAVIOUR OF BEAM-TO-COLUMN BOLTED METALLIC-CUFF JOINTS

BETWEEN PULTRUDED GFRP PROFILES ................................................................................................... 114

David Martins1, João Azevedo1, José A. Gonilha1, João R. Correia1, Mário Arruda1, Nuno Silvestre2

INDENTATION AND IMPACT BEHAVIOUR OF COMPOSITE SANDWICH PANELS FOR CIVIL

ENGINEERING STRUCTURAL APPLICATIONS ......................................................................................... 115

Rui Teixeira1, Mário Garrido1, Miguel Proença1, João R. Correia1, Leigh Sutherland2

EXPERIMENTAL STUDY ON SHEAR PROPERTIES OF GFRP CHANNEL MEMBER ............................ 116

Yuanbin Wang 1, Hitoshi Nakamura 1, Yuya Ishii 2, Yutaro Inari 3, Hiroshi Nakai 4, Masayuki Nishida 5

DIC STRAIN FIELD MEASUREMENT OF FRP PLATES WITH AND WITHOUT HOLES ....................... 117

Brad C. McCoy, P.E.1, Rudolf Seracino, Ph.D. 1, Gregory W. Lucier, Ph.D. 1, Timothy W. Langerhans2

LOCAL BUCKLING OF PULTRUDED GFRP I-SECTION UNDER FLEXURE .......................................... 118

Everton Souza1, Janine Vieira 2, Daniel Cardoso1

ADAPTIVE REUSE OF FRP COMPOSITE WIND TURBINE BLADES FOR CIVIL INFRASTRUCTURE

CONSTRUCTION .............................................................................................................................................. 119

R. Gentry 1, L. Bank 2, J. F. Chen 3, F. Arias 2, and T. Al-Haddad 1

DESCRIPTION & MATERIAL FACTOR OF FRP IN THE STANDARD SPECIFICATION FOR HYBRID

STRUCTURES 2014 BY JSCE .......................................................................................................................... 120

Itaru Nishizaki1, Hitoshi Nakamura2, Yasuo Kitane3, Takashi Matsumoto4, Kunitaro Hashimoto5, Akira

Kobayashi6

FIBER MODEL ANALYSIS ON THE FLEXURAL BEHAVIORS OF CFRP BOX BEAMS ....................... 121

Takashi Matsumoto1, Momoka Nasu2

PREDICTION OF THE WEB CRUSHING CAPACITY OF PULTRUDED GFRP I SECTIONS UNDER

TRANSVERSE LOADING ................................................................................................................................ 122

Xidong Wu 1,Chao Wu 1, *

EXPERIMENTAL STUDY ON THE WEB CRIPPLING BEHAVIOR OF PULTRUDED GFRP CHANNEL

SECTIONS ......................................................................................................................................................... 123

Li-Teng Zhang 1, Xi-Dong Wu 1 and Chao Wu 1, *

SHAKING TABLE TEST ON CFRP CABLE DOME STRUCTURE .............................................................. 124

W. H. Qin1,2, Z. Xi1,2, Y.J. Li1, Z. C. Zhang1 and X. Zhang1

BEHAVIOR OF GFRP WALL PANEL WITH INTERNAL TUNED LIQUID COLUMN DAMPER ............ 125

H. Wu 1, A. Chen 2 and S. Laflamme 3

SPLICE CONNECTION FOR TUBULAR FRP COLUMN MEMBERS ......................................................... 126

C. Qiu 1, Y. Bai 2

BRIDGE PARADIS NORWAY: DESIGN AND ENGINEERING OF A 42M SPAN FULL FRP FOOTBRIDGE

............................................................................................................................................................................ 127

Liesbeth Tromp1, Kees van IJselmuijden 2, Stian Persson 3

EFFECTS OF HOLE GEOMETRY AND BOLT TIGHTENING ON CREEP BEHAVIOR OF PIN-BEARING

PULTRUDED FRP CONNECTIONS ................................................................................................................ 128

Dr. David W. Scott1 and Javaid Anwar2

ELASTIC GRIDSHELL IN COMPOSITE MATERIALS: SOME RECENT DEVELOPMENTS ................... 129

Jean-François Caron1, Olivier Baverel1, Lionel du Peloux1, Cyril Douthe1

FALCON – A MULTI-DISCIPLINARY EFFORT TO PROMOTE FRP BRIDGES IN SWEDEN................. 130

Reza Haghani 1, Erik Olsson1,2

TOWARDS A STRUCTURAL EUROCODE FOR FRP STRUCTURES: THE ROLE OF CEN/TC 250 ....... 131

L. Ascione 1

RC structures internally reinforced by FRP bars .............................................. 132

IMPROVEMENT OF MECHANICAL SHEAR RESISTANCE OF HIGH MODULUS CFRP ROD WITH GFRP

RIBS .................................................................................................................................................................... 132

Hiroaki Hasegawa 1, Nobuhiro Hisabe 1, Yoshiki Onari 2 and Isamu Yoshitake 2

SERVICEABILITY AND MOMENT REDISTRIBUTION OF CONTINUOUS CONCRETE ELEMENTS

REINFORCED WITH STEEL-BASALT BARS ............................................................................................... 135

Mohammad Akiel1, Tamer El-Maaddawy2, Ahmed El Refai3

NUMERICAL MODELING OF THE INTERACTION BETWEEN GFRP REIN-FORCEMENT AND HIGH

STRENGTH CONCRETE DURING HYDRATION PROCESS....................................................................... 136

Slim Kammoun1,2, Ahlem Sdiri1 and Atef Daoud1,3

PARAMETRIC STUDY ON BOND OF GFRP BARS IN ALKALI ACTIVATED CEMENT CONCRETE . 137

Biruk H. Tekle1, Amar Khennane 2, Obada Kayali 3

BOND STRENGTH OF POST-INSTALLED GFRP IN BEAM-COLUMN CONNECTIONS........................ 139

Muhammad S. Bajwa1, 3, Benjamin Z. Dymond1, Rania Al-Hammoud2

EXPERIMENTAL INVESTIGATION OF GEOPOLYMER CONCRETE BEAMS WITH RECTANGULAR

GFRP SPIRAL REINFORCEMENT .................................................................................................................. 140

Ginghis B. Maranan 1, Allan C. Manalo 2, Tanniru Wamshi Krishna 2, Brahim Benmokrane 3

BEHAVIOR OF CONCRETE DEEP BEAMS REINFORCED WITH GFRP HEADED END BARS ............ 141

Ahmed Mohamed1, Ehab El-Salakawy2

INFLUENCE OF DIFFERENT APPROACHES ON DESIGN, DESIGN VALUES AND GENERAL SAFETY

FOR INTERNAL FRP REINFORCEMENT...................................................................................................... 142

André Weber1, Faustin Gaufillet,2

CONTRIBUTION OF SHEAR TRANSFER MECHANISMS AND STRENGTH OF GFRP REINFORCED

CONCRETE ....................................................................................................................................................... 144

Danielle Pacheco 1, Daniel Cardoso 1, Martin Noël 2

A REVIEW ON EXPERIMENTAL DEFLECTIONS IN FRP RC FLEXURAL MEMBERS .......................... 145

Cristina Barris1, Arnau Bover1, Javier Gómez1, Lluís Torres1

NUMERICAL SIMULATION OF SHEAR FAILURE IN SCALED GFRP REINFORCED CONCRETE BEAMS

WITHOUT STIRRUPS ...................................................................................................................................... 146

S. Khodaie 1 and F. Matta 2

EFFECT OF HIGH TEMPERATURES ON THE BOND PERFORMANCE OF GFRP BARS TO CONCRETE

............................................................................................................................................................................ 147

Inês C. Rosa1, João P. Firmo1,2, Luís Granadeiro1, João R. Correia 1

SHEAR TESTS ON GFRP REINFORCED CONCRETE BEAMS USING DIGITAL IMAGE CORRELATION

SYSTEM ............................................................................................................................................................. 148

M. Kaszubska 1, R. Kotynia 1, D. Szczech1, M. Urbaniak2

TESTS ON GFRP REINFORCED CONCRETE CLOSING JOINTS ............................................................... 149

Nader Sleiman1, Maria Anna Polak2

EFFECT OF SURFACE TREATMENT AND TEST CONFIGURATION ON BOND BEHAVIOUR OF GFRP

REBARS ............................................................................................................................................................. 150

Ondrej Janus1, Frantisek Girgle2, Vojtech Kostiha2, Petr Stepánek2

PERFORMANCE STUDY OF A POST-TENSIONED CONCRETE SLAB STRENGTHENED WITH CFRP

USING 24 HR AND CYCLIC LOAD TESTING .............................................................................................. 151

Thanongsak Imjai 1, Surin Sutthiprapa 1 Burachat Chatveera 2 and Udomvit Chaisakulkiet 3

SHRINKAGE BEHAVIOUR OF FIBRE REINFORCED POLYMER GRID REINFORCED INFRA-

LIGHTWEIGHT CONCRETE ........................................................................................................................... 152

Yue Liu 1, Arndt Goldack 1, Mike Schlaich 1, Alex Hückler 1

BOND EVALUATION OF GFRP REINFORCING BARS EMBEDDED IN CONCRETE UNDER

AGGRESSIVE ENVIRONMENTS ................................................................................................................... 153

Alvaro Ruiz Emparanza1, Francisco De Caso Y Basalo 2, Raphael Kampmann 3 and Antonio Nanni4

EXPERIMENTAL STUDY OF CONCRETE BEAMS REINFORCED WITH HYBRID (SFCB AND BFRP)

BARS .................................................................................................................................................................. 154

Yang Yang 1, and Gang Wu 2

BEHAVIOUR OF PRECAST SEGMENTAL CONCRETE BEAMS (PSBS) PRESTRESSED WITH CFRP

TENDONS .......................................................................................................................................................... 155

Thong M Pham*, Tan D Le, and Hong Hao

STUDIES ON DESIGN AND CONSTRUCTION MONITORING OF PRECAST CONCRERE MUNICIPAL

TUNNEL REINFORCED WITH GFRP BARS ................................................................................................. 156

X. Hu1, W. C. Xue1, Fei Peng1, and T. Liu1

EXPERIMENTAL STUDY ON THE BOND BEHAVIOR BETWEEN FRP REBARS AND CONCRETE ... 157

Arnaud Rolland1, Karim Benzarti2, Marc Quiertant3, Pierre Argoul3, Sylvain Chataigner4, Aghiad Khadour5

FLEXURAL BEHAVIOUR OF BFRP REINFORCED BEAMS WITH PRESTRESSED REINFORCEMENT

............................................................................................................................................................................ 158

Mohammad Mirshekari1, Ted Donchev1,Diana Petkova1

EXPERIMENTAL INVESTIGATION ON FLEXURAL BEHAVIOR OF UHPC PANELS REINFORCED

WITH FRP BARS ............................................................................................................................................... 159

Jiaxing Chen1, Zhi Fang 1,2

AXIAL PERFORMANCE CAPACITY OF HOLLOW CONCRETE COLUMNS REINFORCED WITH GFRP

BARS .................................................................................................................................................................. 160

Omar S. AlAjarmeh1, Allan Manalo 1, Warna Karunasena1, Brahim Benmokrane2

PERFORMANCE OF GFRP IN BALCONY SLAB THERMAL BREAKS ..................................................... 161

Sarah Boila1, David Kuhn 2, Kevin Knight 3, John Wells 4, Dagmar Svecova 1

TECHNICAL STANDARDS FOR DEBONDING IN FRP-CONCRETE SYSTEMS: AN EXPERIMENTAL

CONTRIBUTION FOR BASALT-FRP ............................................................................................................. 162

Elisabetta Monaldo1, Francesca Nerilli1, Giuseppe Vairo2

GFRP STRAND PROTOTYPE: EXPERIMENTAL INVESTIGATION AND TECHNOLOGY READINESS

............................................................................................................................................................................ 163

Marco Rossini1, Pedro Jalles1, Gabriele Balconi2, Antonio Nanni1

BEHAVIOR OF GFRP REINFORCED CONCRETE UNDER FLEXION: EXPERIMENTAL TESTS ON REAL

SCALE SLABS................................................................................................................................................... 164

M. Arduini 1 and G. Balconi 2

LOAD DEFLECTION BEHAVIOUR OF SELF-CONSOLIDATING CONCRETE BEAMS PRESTRESSED

WITH CFRP BARS ........................................................................................................................................ - 165 -

S. Krem 1, K. Soudki 2

BOND BEHAVIOUR BETWEEN GFRP RODS AND CONCRETE PRODUCED WITH SEAWATER: AN

EXPERIMENTAL RESEARCH ........................................................................................................................ 166

José Sena-Cruz 2, Eduardo Pereira 1, Emanuel Pereira 1, Nelson Freitas 1, Sérgio Soares 1

FLEXURAL BEHAVIOR OF PULTRUDED GLASS FIBER-REINFORCED POLYMER DISTRIBUTION

POLES ................................................................................................................................................................ 168

Omar I. Abdelkarim1, Jose Manuel Guerrero2, Hamdy M. Mohamed3, Brahim Benmokrane4

Masonry strengthening ............................................................................................................... 169

NON-DIMENSIONAL AXIAL LOAD-MOMENT INTERACTION DIAGRAMS FOR FRP STRENGTHENED

MASONRY WALLS .......................................................................................................................................... 170

Sonia Martínez 1, M. Dolores García2, J. Pedro Gutiérrez1

EXPERIMENTAL RESEARCH INTO DYNAMIC PROPERTIES OF NON-REINFORCED AND FRP

REINFORCED MASONRY BARREL VAULTS ............................................................................................. 171

Jiří Witzany 1, Miroš Pirner 2, Radek Zigler 1, Shota Urushadze 2, Jan Kubát 1, Klára Kroftová 3

ANALYSIS OF THE MECHANICAL BEHAVIOR OF DIFFERENT BASALT-TEXTILE REINFORCED

MORTAR STRENGTHENING SYSTEMS....................................................................................................... 172

Carmelo Caggegi 1, Emma Lanoye1, Denise Sciuto2

AN ANALYTICAL METHOD TO ESTIMATE THE RESISTING BENDING MOMENT OF FRCM

STRENGTHENED MASONRY WALLS SUBJECTED TO OUT-OF-PLANE LOAD ................................... 173

Tommaso D’Antino1, Francesca Giulia Carozzi1, Pierluigi Colombi1, Carlo Poggi1

DESIGN OF THE OUT-OF-PLANE STRENGTHENING OF MASONRY WALLS WITH TEXTILE

REINFORCED MORTAR (TRM) COMPOSITES ............................................................................................ 174

Stefano De Santis1*, Alessandro Bellini2, Gianmarco de Felice1, Claudio Mazzotti3, Pietro Meriggi1

CONFINEMENT OF EXISTING RC AND MASONRY COLUMNS WITH FRCM COMPOSITES: ACI-

RILEM PROVISIONS ........................................................................................................................................ 175

Maria Antonietta Aiello1 and Lesley H. Sneed2

DESIGN RULES FOR IN-PLANE SHEAR STRENGTHENING OF MASONRY WITH FRCM ....................... 176

G.P. Lignola1, M. Di Ludovico1, A. Prota1, M.A. Aiello2, A. Cascardi2, G. Castori3, M. Corradi3

STRUCTURAL BEHAVIOR OF FRP REINFORCED RING BEAMS............................................................ 177

Antonio Borri1, Marco Corradi1*, Giulio Castori1, Vikki Edmondson2

FRP CONFINEMENT OF CLAY BRICK MASONRY COLUMNS UNDER AXIAL LOAD: EXPERIMENTAL

RESULTS ........................................................................................................................................................... 178

Jennifer D’Anna1, Giuseppina Amato2, Jian Fei Chen2, Lidia La Mendola1, Giovanni Minafò1

REPAIR OF A MASONRY WALL WITH AN INNOVATIVE CIMENT BASED COMPOSITE .................. 179

Jean-Patrick Plassiard1, Olivier Plé 1, Pascal Perrotin 1

DESIGN CRITERIA FOR STRENGTHENING OF MASONRY VAULTS WITH TEXTILE REINFORCED

MORTAR ........................................................................................................................................................... 180

G. de Felice1, F. Focacci2, M. Malena1, G. Tomaselli1, M.R. Valluzzi3*

AXIAL COMPRESSIVE BEHAVIOR OF RECYCLED BRICK BLOCK CONCRETE-FILLED FRP TUBES

............................................................................................................................................................................ 181

T. Jiang 1, X.M. Wang 2, G.M. Chen 3, F.M. Ren 4, W.P. Zhang 5

AN EXPERIMENTAL STUDY ON THE COMPRESSIVE BEHAVIOUR OF CALCARENITE MASONRY

COLUMNS WRAPPED BY FIBER REINFORCED MORTAR WRAPS ........................................................ 183

Giovanni Minafò*, Lidia La Mendola, Dionisio Badagliacco, Alessia Monaco, Calogero Cucchiara

EXPERIMENTAL INVESTIGATION OF THE ROLE OF MORTAR JOINTS IN TRM-MASONRY BOND

............................................................................................................................................................................ 184

Paraskevi Askouni1, Catherine Papanicolaou 1

OUT-OF-PLANE BEHAVIOR OF RM WALLS STRENGTHED WITH FRCM COMPOSITE OR NSM WITH

CEMENTITIOUS ADHESIVE .......................................................................................................................... 185

Zuhair Al-Jaberi 1, John J. Myers 2, and Mohamed ElGawady 3

REVERSIBLE FRP-CONFINEMENT OF HERITAGE MASONRY COLUMNS .......................................... 187

Alessio Cascardi 1, Riccardo Dell’Anna 1, Francesco Micelli 1*,

Francesca Lionetto 1, Maria Antonietta Aiello 1, Alfonso Maffezzoli 1

INVESTIGATION ON THE FRCM-MASONRY BOND BEHAVIOUR ......................................................... 188

F. Nerilli 1 and B. Ferracuti 2

Seismic retrofitting .......................................................................................................................... 189

EFFECTIVENESS OF A NOVEL ANCHORAGE SYSTEM FOR FLEXURAL STRENGTHENING OF RC

BEAM-COLUMN JOINTS USING CFRP sheets .............................................................................................. 190

Alireza Akhlaghi1, Davood Mostofinejad 1

GFRP-RC EDGE SLAB-COLUMN CONNECTIONS SUBJECTED TO SEISMIC LOADING ..................... 191

Mohammed El-Gendy1, Ehab El-Salakawy 1

MECHANICAL CHARACTERIZATION OF A RC WALL-SLAB JOIST REINFORCED BY FRP UNDER

ALTERNATING CYCLIC LOADING .............................................................................................................. 193

A.Chalot, L.Michel, E.Ferrier, C.Caggegi, N.Reboul, C.Grazide

CIRCULAR AND SQUARE GFRP-REINFORCED CONCRETE COLUMNS SUBJECTED TO SIMULATED

SEISMIC LOADS ............................................................................................................................................... 194

Zahra Kharal1, Shamim Sheikh1

MODELING PARAMETERS AND ACCEPTANCE CRITERIA FOR FRP-RETROFITTED CONCRETE

COLUMNS SUBJECTED TO SEISMIC LOAD ............................................................................................... 195

Benben Li1,2 and Kent A. Harries2,3

SEISMIC RESPONSES OF THE POST-YIELD HARDENING SINGLE DEGREE OF FREEDOM (SDOF)

SYSTEMS INCORPORATING FRP MATERIALS ......................................................................................... 196

H.L. Qiang 1, P. Feng 1, Z. Qu 2 and L.P. Ye 1

REPAIR AND STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH THE USE OF TEXTILE

REINFORCED MORTARS (TRM’S) ................................................................................................................ 197

Theofanis Krevaikas

Steel strengthened structures ................................................................................................. 198

FATIGUE TESTS ON STEEL PLATES WITH AN INCLINED CENTER CRACK REPAIRED WITH CFRP

STRAND SHEETS ............................................................................................................................................. 199

Tao Chen1, Lingzhen Li 1, Ningxi Zhang 1 , Yuya Hidekuma 2

FACTORS INFLUENCING BOND OF CFRP TO STEEL ............................................................................... 200

Manuel A G Silva1, Pedro Ribeiro 2, Hugo Biscaia 3

EXPERIMENT STUDY ON BOND BEHAVIOR BETWEEN CFRP PLATE AND STEEL .......................... 201

Yuyang PANG1, Gang WU2, Haitao WANG3

STUDY ON REPAIR METHOD FOR CORRODED GUSSET PLATE CONNECTION BY BONDING CFRP

SHEET ................................................................................................................................................................ 202

Ngoc Vinh PHAM1, Takeshi MIYASHITA2, Kazuo OHGAKI3, Yusuke OKUYAMA4, Akira KOBAYASHI5,

Yuya HIDEKUMA6, Takeshi HIROSE7, and Takuya HARADA8

FRACTURE ANALYSIS OF SINGLE-EDGE CRACKED TUBULAR STEEL BEAM REHABILITATED BY

CFRP SHEETS ................................................................................................................................................... 203

Mahdi Razavi Setvati1, Zahiraniza Mustaffa2 and Dokyun Kim3

FEASIBILITY OF ACCELERATED CURING FOR STRENGTHENING OF STEEL MEMBERS BY

PRESTRESSED BONDED CFRP PLATES ...................................................................................................... 204

Ardalan Hosseini 1,2, Elyas Ghafoori 1, Abdola Sadeghi Marzaleh 1, Masoud Motavalli 1,3

GLASS TRANSITION EVALUATION OF COMMERCIALLY AVAILABLE EPOXY ADHESIVES FOR

STRENGTHENING OF STEEL STRUCTURES WITH BONDED CFRP PLATES ....................................... 205

Ardalan Hosseini 1,2, Michel Barbezat 3, Julien Michels 1,4, Elyas Ghafoori 1, Masoud Motavalli 1,5, Giovanni

Terrasi 3

FASSTBRIDGE METHODOLOGY AND STRENGTHENING SYSTEM: THE JARAMA BRIDGE

EXPERIENCE .................................................................................................................................................... 207

David García-Sánchez1, Mazen Wabeh2, Frank Lehmann 3 Sylvain Chataigner4, Luis Sopeña5, Veit Birtel6

PROPOSAL OF A METHODOLOGY BASED ON FINITE ELEMENT ANALYSES FOR THE DESIGN OF

BONDED CFRP REINFORCEMENT OF STEEL CRACKED ELEMENTS .................................................. 208

Emilie Lepretre1, Florent Chemin2, Sylvain Chataigner2, Lamine Dieng2, Laurent Gaillet2

DEFINITION AND ASSESSMENT OF AN ADHESIVELY BONDED COMPOSITE REINFORCEMENT IN

FATIGUE FOR STEEL STRUCTURES DEVELOPPED IN FASSTBRIDGE PROJECT .............................. 209

Sylvain Chataigner1, Karim Benzarti2, Gilles Foret2, Jean-François Caron2, Gianluca Gemignani3, Matteo

Brugiolo3, Veit Birtel4, Frank Lehmann4, Inigo Calderon5, Ignacio Piniero5

MODEL UNCERTAINTY OF EXTERNALLY BONDED CFRP-TO-STEEL JOINTS.................................. 210

Qian-Qian Yu 1, Dongming Zhang 2, Xiang-Lin Gu 3, Hongwei Huang 2

STRESS INTENSITY FACTOR FOR DOUBLE-SIDED CRACKED STEEL BEAM STRENGTHENED WITH

CFRP PLATES ................................................................................................................................................... 211

Hai-Tao Wang1, Gang Wu2, Yu-Yang Pang 2

IMPROVEMENT OF FATIGUE DURABILITY OF WELDED GUSSET JOINTS BY CF SHEETS USING

VARTM TECHNIQUE ...................................................................................................................................... 212

Visal Thay 1, Chang Tan 1, Hitoshi Nakamura 1, Takahiro Matsui 2, Fan Lin 3

DEVELOPMENT OF A SENSOR FOR MONITORING MECHANICALLY STRESSED ADHESIVE JOINTS

............................................................................................................................................................................ 213

F. Lehmann1, V. Birtel1, J. Wang1, S. Chataigner2, O. Konrad1

BEHAVIOR OF CONICAL STEEL TANKS STRENGTHENED BY CFRP ................................................... 214

Mohamed S. A. Saafan1

FINITE ELEMENT ANALYSIS OF STEEL-CFRP BONDED JOINTS WITH VARIOUS NON-LINEAR

TRACTION-SEPARATION LAWS .................................................................................................................. 215

Vladimir Berka 1, Mina Dawood1

SHAPE MEMORY ALLOY (SMA) STRIPS FOR FATIGUE STRENGTHENING OF CRACKED STEEL

PLATES .............................................................................................................................................................. 216

M.R. Izadi 1, 2, E. Ghafoori 1,3, M. Motavalli 1, 2, S. Maalek 2, A. Hosseini 1, 4

APPLICATION OF PRE-STRESSED UN-BONDED CFRP FOR STRENGTHENING OF METALLIC

STRUCTURES ................................................................................................................................................... 218

E. Ghafoori 1,2, A. Hosseini 1, 3, E. Pellissier 4, M. Hueppi 4, M. Motavalli 1, 5

INCREASING THE REMAINING FATIGUE SERVICE LIFE OF STEEL STRUCTURES USING

ADHESIVELY BONDED COMPOSITES - DESIGN APPROACH DEVELOPED IN FASSTBRIDGE ....... 219

Mazen Wahbeh1, Rami Boundouki1, Mark Weidemueller2, Sylvain Chataigner3, Elena Martín4, Luis Sopeña4

SMALL-DIAMETER CFRP SHEAR STRENGTHENING SYSTEM FOR STEEL BRIDGE GIRDERS ...... 220

Hamid Kazem1, Ye Zhang 1, Sami Rizkalla 1, Rudolf Seracino 1, Akira Kobayashi2

BUCKLING BEHAVIOR OF STEEL COLUMNS STRENGTHENED BY PRE-STRESSED (PS) CFRP

LAMINATES...................................................................................................................................................... 221

L.L. Hu, P. Feng, H.L. Qiang and Y.C. Zou

LARGE-SCALE SPACE FRAMES ASSEMBLED USING GFRP COMPOSITES AND ALUMINUM NODAL

JOINTS ............................................................................................................................................................... 222

Lei Zhang 1, Yu Bai 2, Run Guo 1, and Jiawen Mao 1

A LIFE CYCLE ANALYSIS APPROACH APPLIED TO THE STRENGTHENING OF STEEL BRIDGES 223

A. Orcesi 1, A. Feraille 2 and S. Chataigner 3

Strengthening of concrete structures ............................................................................. 224

CFRP STRENGTHENING OF BUBBLEDECKS WITH OPENINGS ............................................................. 225

Nazar Oukaili1 and Hammad Merie 2

FLEXURAL DEFORMATION CAPACITY OF FRP-CONFINED CONCRETE COLUMNS ....................... 226

N. Hany 1 and M. Harajli 2

STOCHASTIC INVERSE APPROACH FOR DURABILITY OF CFRP-CONFINED CONCRETE .............. 227

Yongcheng Ji 1, Troy Butler 2 and Yail J. Kim 3

AXIAL COMPRESSIVE BEHAVIOUR OF CFFT COLUMNS WITHOUT AND WITH STEEL FIBRES ... 228

Qasim S. Khan 1, Joshua C. Tinker 2, M. Neaz Sheikh 3 and Muhammad N. S. Hadi 3

CONFINING CONCRETE COLUMNS WITH BASALT FIBRE TEXTILE REINFORCED ECC ................ 229

Y. Zhuge1; A.N. AL-Gemeel1

ASSESSMENT OF COMPRESSIVE STRENGTH OF STEEL-REINFORCED GROUT JACKETED

CONCRETE COLUMNS ................................................................................................................................... 231

Georgia E. Thermou1,2, Iman Hajirasouliha1

STUDY OF RECTANGULAR CONCRETE COLUMNS REINFORCED WITH EXTERNAL FRP ............. 232

Ana De Diego1, Sonia Martínez 1, Luis Echevarría 1, José Pedro Gutiérrez1

EXPERIMENTAL STUDY OF FRP-CONFINED CONCRETE SUBJECTED TO PARTIAL UNLOADING

AND PARTIAL RELOADING .......................................................................................................................... 233

Pengda Li1, Yufei Wu 1,2, Yingwu Zhou 1, Feng Xing 1

EXPERIMENTAL STUDY ON CFRP REPAIRING PLAIN CONCRETE ...................................................... 234

Mariem LIMAIEM1, 2, Elhem GHORBEL 1, Oualid LIMAM 2, Julien MERCIER 3

MULTI-LAYER TRC-TSR INTERNAL CONFINEMENT FOR HIGH-STRENGTH CIRCULAR

REINFORCED-CONCRETE COLUMNS ......................................................................................................... 235

Rami Eid, Avraham Cohen, Reuven Guma, Eliav Ifrah, Netanel Levi, Avidor Zvi

BEHAVIOUR OF CFRP WRAPPED REINFORCED CONCRETE COLUMNS UNDER UNIAXIAL

COMPRESSION ................................................................................................................................................. 236

Asad-ur-Rehman Khan1, Shamsoon Fareed1

AXIAL COMPRESSIVE BEHAVIOUR OF HYBRID FRP CONFINED CONCRETE .................................. 237

Filipe Ribeiro1, José Sena-Cruz 2, Eduardo Júlio 1, Fernando Branco 3

A STUDY ON FRP-CONFINED CONCRETE IN PRESENCE OF DIFFERENT PRE-LOAD LEVELS ...... 239

Francesco Micelli 1, Alessio Cascardi 1, Maria Antonietta Aiello 1

MINERAL COMPOSITE AS A SUSTAINABLE BONDING ALTERNATE TO BENEFIT CFRP RETROFIT

............................................................................................................................................................................ 240

Raghavendra Vasudeva Upadhyaya1, T.G. Suntharavadivel2, Kai Duan3

BEHAVIOUR OF CFRP CONFINED RC SQUARE COLUMNS UNDER ECCENTRIC COMPRESSIVE

LOADING .......................................................................................................................................................... 241

Faiz U.A. Shaikh*, Reza Alishahi and Prabir K. Sarker

COMPRESSIVE BEHAVIOR OF CONCRETE COLUMNS AXIALLY-LOADED BEFORE CFRP-

WRAPPING. REMARKS BY EXPERIMENTAL-NUMERICAL INVESTIGATION. ................................... 242

Marco Filippo Ferrotto1, Oliver Fischer2, Roland Niedermeier2, Liborio Cavaleri1

STUB COLUMN TESTS OF FRP-CONFINED RUBBER CONCRETE WITH VARIOUS REPLACEMENT

RATIOS .............................................................................................................................................................. 243

Chun-Wa Chan1, Shi-Shun Zhang2, Tao Yu3

BEHAVIOUR OF FRP-CONFINED RUBBERISED CONCRETE: AN EXPERIMENTAL INVESTIGATION

............................................................................................................................................................................ 244

Samar Raffoul 1, Reyes Garcia 1, David Escolano-Margarit 1, Maurizio Guadagnini 1, Iman Hajirasouliha 1,

Kypros Pilakoutas 1

RETROFITTING OF BRIDGE GIRDER WITH CFRP .................................................................................... 245

Anees Muhammad1, Samiullah Qazi 2

DEVELOPMENT OF DESIGN GUIDELINES FOR BEAMS PRESTRESSED WITH CFRP SYSTEMS ..... 246

A. Belarbi 1, H. Tahsiri1, P. Poudel1, M. Reda1, M. Dawood1, and B. Gencturk 2

QUANTITATIVE APPROACH TO ANCHORING SPIKES DESIGN IN FLEXURAL APPLICATIONS .... 247

Marco Rossini1, Antonio Nanni 1, Carlo Poggi 2

FRACTURE MECHANICS BASED CALCULATION MODEL OF FLEXED RC ELEMENTS

STRENGTHENED WITH FRP .......................................................................................................................... 248

Justas Slaitas1, Juozas Valivonis1

EXPERIMENTAL AND FINITE ELEMENT STUDY ON RC BEAMS RETROFITTED WITH FULL-LENGTH

AND SPLICED FRP LAMINATES ................................................................................................................... 249

Akram Jawdhari 1, Issam Harik 1

EXPERIMENTAL AND NUMERICAL ANALYSIS OF STRENGTHENED SHORT REINFORCED

CONCRETE CORBEL BONDED BY CFRP UNDER CYCLIC LOADS ........................................................ 250

Jules Assih1, Ivelina Ivanova1,2, Veselin Stankov1,2 Dimitar Dontchev2

REHABILITATION OF REINFORCED CONCRETE STRUCTURES BY FRP AND WOOD ..................... 251

Cecile GRAZIDE*, Emmanuel FERRIER, Laurent MICHEL

FLEXURAL BEHAVIOUR OF SRG STRENGTHENED REINFORCED CONCRETE BEAMS .................. 252

Luciano Ombres 1; Salvatore Verre2

INTERFACIAL BOND DEGRADATION OF FRP STRENGTHENED RC BEAMS SUBJECTED TO FREEZE-

THAW CYCLES ................................................................................................................................................ 253

Jiawei Shi1, Zhishen Wu 2

INFLUENCE OF BOND DETERIORATION ON THE FLEXURAL RESPONSE OF FRP STRENGTHENED

RC BEAMS ........................................................................................................................................................ 254

Rebecca Gravina1, Hasret Aydin1, Philip Visintin2

TIME-DEPENDENT RELIABILITY ANALYSIS OF FRP STRENGTHENED REINFORCED CONCRETE

BEAMS CONSIDERING MATERIAL DETERIORATION AND STOCHASTIC LOADING ...................... 255

Xiaoxu Huang1, Yingwu Zhou1

USE OF CFRP AS AN IMPRESSED CURRENT ANODE FOR THE CATHODIC PROTECTION OF STEEL

REINFORCED REBAR ..................................................................................................................................... 256

X. Hallopeau 1, C. Tourneur 1, V. Buchin-Roulié 1 and J. Mercier 1

EXPERIMENTAL AND NUMERICAL INVESTIGATION ON TORSIONAL STRENGTHENING OF BOX RC

STRUCTURES USING NSM FRP .................................................................................................................... 257

Chandan C Gowda1, Joaquim A O Barros 2 & Maurizio Guadagnini3

MODELLING OF CFRP LAMINATES APPLIED ACCORDING TO THE ETS/NSM TECHNIQUE .......... 258

Carlos Nonato da Silva, Jacopo Ciambella, Joaquim Barros, Inês Costa

EFFECT OF STEEL REINFORCEMENT IN FLEXURAL STRENGTHENING OF RC SLABS USING

PRESTRESSED NSM CFRP LAMINATES ...................................................................................................... 259

Mohammadreza Mostakhdemin Hosseini1, Salvador Dias2, Joaquim Barros2

FLEXURAL CAPACITY OF FRP RC BEAMS STRENGTHENED WITH NSM TECHNIQUE ................... 260

C. Barris1, P. Sala2, J. Gómez2, Lluís Torres2

INFLUENCE OF ADHESIVE TYPE ON THE FLEXURAL BEHAVIOUR OF RC SLABS STRENGTHEND

WITH NSM-CFRP SYSTEMS ........................................................................................................................... 261

José Ricardo Cruz 1, José Sena-Cruz 1, Pedro Fernandes 1, Anja Borojevic 1, Arkadiusz Kwiecień 2, Bogusław

Zając 2

NSMR STRENGTHENING OF SHORT RC BEAMS USING ACTIVATED ANCHORAGE ....................... 263

J.W. Schmidt 1, K. D. Hertz 1 and P. Goltermann 1

COMPARISON BETWEEN DIFFERENT STRENGTHENING SCHEMES FOR PUNCHING SHEAR OF

FLAT PLATE SLABS ........................................................................................................................................ 264

S. Elkholy 1,2, A. Godat 2, M. Elassaly 1 and E. Rabee 1

INFLUENCE OF THE AREA OF CFRP LAMINATES ON IMPROVING THE PUNCHING SHEAR

CAPACITY OF SLAB-COLUMN CONNECTION .......................................................................................... 265

*H. Akhundzada 1, *T. Donchev 1 D. Petkova 1 and N. Kolikar 1

DEVELOPMENT OF THE NEW CFRP STRIP PRESTRESSING SYSTEM FOR STRUCTURAL

STRENGTHENING ........................................................................................................................................... 266

Piątek Bartosz1, Siwowski Tomasz1

EFFECTIVENESS OF FABRIC REINFORCED CEMENTITIOUS MORTAR (FRCM) IN STRENGTHENING

BEAMS WITH HIGH REINFORCEMENT RATIOS ....................................................................................... 267

T. N. S. Billows1 and A. Rteil2

DESIGN OF REINFORCED CONCRETE T-BEAMS STRENGTHENED IN SHEAR WITH EXTERNALLY

BONDED FRP COMPOSITES .......................................................................................................................... 268

Samir Dirar 1,2, Michael Qapo 3, Marios Theofanous 1

FRP SHEAR STRENGTHENED RC BEAMS: AN ANALYTICAL MODEL ................................................. 269

Cheng Chen1, Lijuan Cheng 2

CRACK PROPAGATION OF RC BEAM STRENGTHENED IN SHEAR BY CFRP GRID .......................... 272

Ngoc Linh Vu 1,2, Kimitaka Uji 1, Kentaro Ohno 1

INFLUENCE OF SIZE ON THE BEHAVIOR OF RC T-BEAMS STRENGTHENED IN SHEAR WITH

EXTERNALLY BONDED CFRP ...................................................................................................................... 273

Zine El Abidine Benzeguir1, Georges El-Saikaly2, Omar Chaallal3

RELIABILITY OF DIC MEASUREMENTS FOR THE STRUCTURAL MONITORING OF FRP RC

ELEMENTS ........................................................................................................................................................ 274

Matteo Di Bendetti1, Javier Gómez2, Szymon Cholostiakow3, Hamed Fergani3, Cristina Barris2,

Maurizio Guadagnini3

REPAIR AND STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH THE USE OF TEXTILE

REINFORCED MORTARS (TRM’S) ................................................................................................................ 275

Theofanis Krevaikas

ROBUST MODELING OF ANGLE-PLY LAMINATE RESPONSE FOR STRENGTHENING APPLICATIONS

............................................................................................................................................................................ 276

H. A. Rasheed 1 and H. Charkas 2

FLEXURAL BEHAVIOR OF PRE-CRACKED FRP BEAMS STRENGTHENED WITH CARBON FIBER

LAMINATES...................................................................................................................................................... 277

Himanshu Chawla1 and Shamsher Bahadur Singh2

Fire blast and impact loading ............................................................................................... 278

BLAST RESPONSE OF RC SLABS WITH EXTERNALLY BONDED REINFORCEMENT ....................... 279

Azer Maazoun 1,2, Bachir Belkassem 2, Rodrigo Mourão 2, Stijn Matthys 3, D.Lecompte2 , John Vantomme 2

EFFECT OF THE GEOMETRY AND IMPREGNATION OF THE TEXTILE REINFORCEMENT ON THE

MECHANICAL AND THERMOMECHANICAL PROPERTIES OF A TEXTILE REINFORCED CONCRETE

(TRC) .................................................................................................................................................................. 280

Tala Tlaiji1, Xuan Hong Vu1, Emmanuel Ferrier1, Amir Si Larbi2

EXPERIMENTAL STUDY OF THERMOMECHANICAL PERFORMANCE OF CFRP REINFORCED

CONCRETE STRUCTURE SUBJECTED TO ELEVATED TEMPERATURE .............................................. 281

Phi Long NGUYEN1,2, Xuan Hong VU1, Emmanuel FERRIER1

MESOSCALE MODELING OF THE ELEVATED TEMPERATURE BEHAVIOR OF THE BASALT TEXTILE

REINFORCED CONCRETE .............................................................................................................................. 283

Manh Tien TRAN1,2, Xuan Hong VU1, Emmanuel FERRIER1

FIRE BEHAVIOUR OF GFRP-REINFORCED CONCRETE SLAB STRIPS: FIRE RESISTANCE TESTS AND

NUMERICAL MODELLING ............................................................................................................................ 285

Inês C. Rosa1, João P. Firmo1,2, Carolina Churro1, Pedro Santos1, Mário R. T. Arruda, João R. Correia 1

FIBRE-REINFORCED INTUMESCENT COATINGS AS A FIRE-SAFE CONFINING MATERIAL FOR

CONCRETE COLUMNS ................................................................................................................................... 286

Zafiris Triantafyllidis 1 and Luke Bisby 1

EXPERIMENTAL AND ANALYTICAL ANALYSIS OF THE THERMOMECANICAL BEHAVIOUR AT

ELEVATED TEMPERATURE OF THE TEXTILE REINFORCED CONCRETE (TRC): EFFECT OF THE

HYDRIC STATE OF TRC ................................................................................................................................. 287

Mohamed SAIDI, Xuan Hong VU, Emmanuel FERRIER

TWO-DIMENSIONAL MODELING OF THERMO-MECHANICAL RESPONSES OF GFRP BOX BEAM

SUBJECTED TO ISO-834 FIRE ........................................................................................................................ 289

Lingfeng Zhang1, Lu Wang 2, Weiqing Liu 3*

STRUCTURAL BEHAVIOR OF CFRP CONFINED RC BRIDGE BENT UNDER IMPACT LOADING .... 290

Charles Plante1, Nathalie Roy1, Charles-Philippe Lamarche1, François Settecasi1

TEMPERATURE EFFECT ON THE BOND BEHAVIOUR OF A TRANSVERSELY COMPRESSED

MECHANICAL ANCHORAGE SYSTEM ....................................................................................................... 291

Luis Correia1, Cristina Barris2, José Sena-Cruz3

NUMERICAL SIMULATIONS OF GFRP-RC SLABS IN FIRE ..................................................................... 293

Antonio Bilotta1, Alberto Compagnone1, Emidio Nigro1

MULTIPHYSICS INVESTIGATIONS INTO NSM CFRP AT ELEVATED TEMPERATURES ................... 294

Thushara Siriwardanage 1 and Yail J. Kim 2

Practical applications ................................................................................................................... 295

NDT SIGNAL ANALYSIS OF CFRP-LAMINATE BOND ON RC BRIDGES .............................................. 296

Kenneth C. Crawford

I75 BRIDGE OVER SEXTON/KILFOIL DRAIN, THE LONGEST HIGHWAY BRIDGE SPAN

PRESTRESSED WITH CFRP STRANDS ......................................................................................................... 297

Nabil Grace1,4, Matthew Chynoweth2, Tsuyoshi Enomoto3, Mena Bebawy1

REPAIR OF PANAMA'S 50-YEAR-OLD BRIDGE WITH CFRP RODS ....................................................... 298

Julien Mercier1, Vanessa Buchin1, Christian Tourneur 1, Guillermo Medina2

PERFORMANCE STUDY OF A POST-TENSIONED CONCRETE SLAB STRENGTHENED WITH CFRP

USING 24 HR AND CYCLIC LOAD TESTING .............................................................................................. 300

Thanongsak Imjai 1, Burachat Chatveera 2 and Udomvit Chaisakulkiet 3

DESIGN AND CONSTRUCTION OF A HYBRID DOUBLE-SKIN TUBULAR ARCH BRIDGE ............... 301

Leo de Waal1, Shuan Jiang1, Juan Torres1, Guang-Ming Chen2, Jin-Guang Teng3, Paul Rodman4, Peter Burnton5,

Dilum Fernando1,*

DISTRIBUTED OPTICAL FIBRE SENSORS TO MONITOR PRESTRESSED CONCRETE BRIDGE BEAM

STRENGTHENED WITH BONDED FRP ........................................................................................................ 302

Aghiad Khadour1, Marc Quiertant1, Gonzague Six1, Corentin Le Roy2, Christophe Aubagnac2

DEVELOPMENT OF A MODULAR FOOTBRIDGE WITH PRE-TENSIONED CFRP REINFORCEMENT –

PRE-DESIGN AND DIMENSIONING OF BOND ANCHORAGE ZONE ...................................................... 303

Sophia Perse1, Christian Knorrek1, Norbert Will 1, Josef Hegger 1

COMPOSITE RAILWAY SLEEPERS – NEW DEVELOPMENTS AND OPPORTUNITIES ....................... 304

Allan Manalo1, Peter Schubel1 and Wahid Ferdous2

NDT SIGNAL ANALYSIS OF CFRP- BOND ON RC BRIDGES LAMINATE ............................................. 305

Kenneth C. Crawford

DISTRIBUTED OPTICAL FIBRE SENSORS TO MONITOR PRESTRESSED CONCRETE BRIDGE BEAM

STRENGTHENED WITH BONDED FRP ........................................................................................................ 305

Aghiad Khadour1, Marc Quiertant1, Gonzague Six1, Corentin Le Roy2, Christophe Aubagnac2

SMART MONITORING OF THE FRP COMPOSITE BRIDGE WITH DISTRIBUTED FIBRE OPTIC

SENSORS ........................................................................................................................................................... 307

T. Siwowski1, M. Rajchel1, R. Sienko2 and L. Bednarski3

CONSTRUCTION OF NIPIGON RIVER CABLE-STAYED BRIDGE USING PRECAST CONCRETE

PANELS REINFORCED WITH GLASS FRP REBARS .................................................................................. 308

Hamdy M. Mohamed1 and Brahim Benmokrane2

Keynotes




TECHNICAL SPECIFICITIES WHEN DESIGNING WITH COMPOSITE MATERIALS

– CASE OF BUILDING AND ARCHITECTURE

Samuel Durand1

1 : MECA Design Office

12 rue du chapeau rouge

F- 44000 NANTES [email protected]

Composite materials in architecture and building are nowadays frequently used. In addition to the recurrent lightening and

excellent resistance to environmental conditions, composite materials can lead to new shapes and architectural details in

building and construction (Millennium dome à London, 2000; Princess Nora University dome, Riyadh, 2010, roof of H.H.R.,

2014 in Jeddah and Mecca, domes CSCOR in Paris, 2015).

From a design office point of view, cladding, envelopes, roofs or structural elements made of composite materials have their

own specificities, making them specific to their counterparts in concrete, steel or wood. A poor knowledge of the specificities

of composite materials can lead to a non-optimized design also called "black metal".

Fig. 1. Toiture H.H.R. à Jeddah, water tests

Composite materials are partially covered by standards or regulations for building as for Eurocodes types. Standardization work

is on going [2] to reduce this lack. The design of composite material parts must at least take into account some specificities

such as orthotropy, creep behavior, the influence of humidity and temperature on mechanical characteristics and fracture modes

that can sometimes be fragile ( fiber breaks, delaminations), or progressive (inter-fiber or resin damage). The safety factors

must be adapted to the failure mode and the manufacturing process.

The designer must also in early project phases, choose from many manufacturing methods (pultrusion, wet molding, infusion,

prepreg, ...). Surface aspect, appearance, mechanical performance and ultimately cost are strongly related to the limits and

possibilities of the manufacturing process. The work on the optimization of tools must be carried out in parallel with the first

budget estimates.

Fire resistance and performance are a key element to specify in the case of composite materials. Thermosetting resins commonly

used (polyester, vinylester, epoxy) are combustible and flammable. The addition of flame retardant fillers and an intumescent

gelcoat may be necessary to achieve a minimum fire performance but the implementation of these resins then becomes more

difficult. Advances are expected on the development of fire-resistant resins suitable for implementation by the infusion process.

mailto:[email protected]

Fig. 2. Dômes CSCOR -PARIS before lifting

Références

[1] DURAND S. BILLAUDEAU E., LUBINEAU G. « Design Analysis of GRP Panels for the Roof of the Haramain High

Speed Railway Jeddah Station». International Conference on Sandwich Structures, ICSS10, NANTES, 2012.

[2] ASCIONE L. TROMP Liesbeth « Development of the Eurocode, FRP Technical Report WG4 FRP Structures».

Composite In Construction, CompIc2015, AMSTERDAM, 2015.

[3] CARON JF. « Matériaux composites pour la construction: état de l’art et spécificités». Séminaire AMAC, AUSSOIS,

2011.

Biographie Samuel Durand is the co-creator of the design office MECA, specialized in innovative structures for building and construction.

Since 2006, MECA has been involved in many composite materials projects, in France and abroad (Rehabilitation of ESIEE

in Noisy le Grand 2007, Roof of Multimodal exchange center at Saint Nazaire 2010, Roofs of H.H.R. train stations 2012-2014

in Jeddah and Mecca, Domes CSCOR in Paris, 2015, …).




DEVELOPMENT OF UK GUIDANCE FOR DESIGNERS OF FRP BRIDGES

N.Farmer

Executive Director, Tony Gee and Partners LLP

Esher, Surrey, UK

KEYWORDS

FRP, guidance for designers, bridges, structural, processing, inspection, repair.

ABSTRACT

A team of design and construction practitioners, with assistance from academia, has been producing guidance for

clients and their designers, and for suppliers who would like to procure FRP bridges, but need reassurance that

those involved in the process can be guided by an engineering reference document that is accepted as state-of-the-

art by experts in this specialist field. Publication of the guidance document is being progressed by the Construction

Sector Group of the Trade Association Composites UK and is due for publication in 2018. The paper explains

why the guidance is required and introduces each chapter by highlighting key recommendations in the guidance.

To give context to the guidance, case studies will be given in the paper to illustrate the types of FRP bridges already

designed and constructed in the UK.




OPPORTUNITIES FOR RECYCLING AND REUSE OF FRP COMPOSITES FOR

CONSTRUCTION IN A CIRCULAR ECONOMY

Lawrence C. Bank

City University of New York

ABSTRACT

Sustainability and green engineering have evolved into a more comprehensive framework known as the Circular

Economy. The importance to this shift in thinking to the FRP composites for construction industry will be

discussed. The aerospace and automotive sectors of the composites industry are moving rapidly to embrace the

circular economy concepts such as design for reuse, adaptability, modularity, recycling, reclamation, life cycle

assessment, materials flow analysis and industrial ecology. Current major projects in Europe and the US will be

reviewed. Examples of materials testing and concepts from an ongoing NSF funded US/Ireland/Northern Ireland

Tripartite research project on the reuse of glass/polymer wind turbine blades will be presented.




RECENT DEVELOPMENTS ON FRP REBARS AS INTERNAL REINFORCEMENT

IN CONCRETE STRUCTURES AND FIELD APPLICATIONS

Brahim Benmokrane1 and Hamdy M. Mohamed2

1Department of Civil Engineering, University of Sherbrooke, Quebec, Canada, J1K2R1.

[email protected]

2Department of Civil Engineering, University of Sherbrooke, Quebec, Canada, J1K2R1.

Corresponding author:[email protected]

KEYWORD

Fields applications and case studies; Structure; FRP internal reinforcement.

ABSTRACT

In the last decade, there has been a rapid increase in using noncorrosive fiber-reinforced polymers (FRP)

reinforcing composite bars for concrete structures due to enhanced properties and cost-effectiveness. The FRP bars

have been used extensively in different applications such as bridges, parking garages, water tanks, tunnels and

marine structures in which the corrosion of steel reinforcement has typically led to significant deterioration and

rehabilitation needs. Many significant developments from the manufacturer, various researchers and Design Codes

along with numerous successful installations have led to a much higher comfort level and exponential use with

designers and owners. After years of investigation and implementations, public agencies and regulatory authorities

in North America has now included FRP as a premium corrosion resistant reinforcing material in its corrosion

protection policy. Currently, AASHTO LRFD Bridge Design Specifications and the Canadian Highway Bridge

Design Code contain design provisions for the design of concrete bridge members reinforced with FRP bars. As a

result, well over 500 bridges across Canada and USA have been designed and constructed using FRP bars. This

paper presents a summary and overview of different recent field applications of FRP bars in different types of civil

engineering concrete infrastructures.






HYBRID FRP-CONCRETE-STEEL TUBULAR MEMBERS

Tao Yu

University of Wollongong, Australia. Email: [email protected]

KEYWORDS

FRP, concrete, steel, hybrid members, tubular members, confinement.

ABSTRACT

Hybrid fibre-reinforced polymer (FRP)-concrete-steel (FCS) tubular members are an emerging type of structural

members. These hybrid members involve the use of an external FRP tube as a confining device and a corrosion-

resistant skin, a concrete infill, and encased steel reinforcement of various forms (e.g. steel bars, a steel section, or

a steel tube). In such members, the FRP tube is generally designed to possess only a small axial stiffness so that

its confinement effectiveness on the concrete is not compromised by buckling due to substantial axial compressive

stresses, while the potential buckling of steel reinforcement is well restrained by the confined concrete, leading to

excellent structural performance. This paper offers an overview of existing research on hybrid FCS tubular

members before providing a summary of several novel forms of such members recently developed at the University

of Wollongong.




STRUCTURAL BEHAVIOR OF FRP-REINFORCED GEOPOLYMER CONCRETE

SANDWICH WALL PANELS FOR PREFABRICATED CONSTRUCTION

Jian-Guo DAI* and Jun-Qi HUANG

Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong,

China. Email: [email protected]

KEYWORDS FRP; geopolymer concrete; sandwich wall panel; connector

ABSTRACT Prefabricated concrete sandwich panels (PCSPs) consist of two concrete wythes and a thermal insulation layer

between them. They have great potential to be used for prefabricated building construction. This paper

experimentally studies the development of a new PCSP system. The two exterior wythes are made of FRP-

reinforced geopolymer concrete while FRP tubular connectors are used to realize the composite action. The

reported tests include: (1) the structural performance of FRP tubular connectors; (2) the structural performance of

steel and BFRP rebar reinforced geopolymer concrete one-way slabs; (3) the structural performance of the formed

sandwich wall panels subjected to out-of-plane loading. Due to its green feature and its structural efficiency, the

developed PCSP system may find wide applications in prefabricated construction which is popular in Hong Kong

and the rest of China.

Composite Material




SHEAR TESTING OF DIFFERENT TYPE AND SIZE OF GFRP REINFORCING

BARS

A.S. Genikomsou 1, G.P. Balomenos 2 and M.A. Polak 3

1 Queen’s University, Department of Civil Engineering, Kingston, Canada,

Email:[email protected]

2 Rice University, Department of Civil and Environmental Engineering, Houston, USA.

3 University of Waterloo, Department of Civil and Environmental Engineering, Waterloo, Canada.

KEYWORDS:

Shear testing; GFRP bars; straight and bent bars; failure modes; bar coating; shear stiffness.

ABSTRACT:

Shear testing of Glass Fiber-Reinforced Polymer (GFRP) reinforcing bars can be considered for material

specifications, quality control, quality assurance and structural design purposes. The shear testing procedure

requires the cutting blades of the shear device to match exactly the bar’s diameter, therefore, for each different bar

diameter new blades would have to be manufactured. In this research, a developed device to test GFRP bars in

shear is manufactured based on both ASTM D7617 and CSA S806-12 standards. The paper aims to provide

information about the significance of shear testing of GFRP bars and the potential outcomes of this type of test.

For that purpose, different types of GFRP bars (straight and bent) provided by two different suppliers (sand/ribbed

coating), are studied. The conducted tests consider GFRP reinforcing bars with measured diameter 18 mm. Then,

the bars are “shaved” using a lathe machine to exclude the external coating and their diameter is reduced to 15.5,

13.5 and 10 mm. The idea of testing GFRP bars with reduced diameter that excludes the effect of the outer treated

surface can possibly provide more unbiased information for quality control. Finally, discussion on the failure

modes and stiffness is presented for both straight and bent bars.




SALT WATER AND ALKALINE ATTACK ON GFRP REBARS

Miguel M. Estêvão1, Manuel A. G. Silva2 , Fernando F. S. Pinho3

1Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia, Portugal;

2 Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia, Portugal Email: [email protected]);

3 Universidade Nova de Lisboa, CERIS and Faculdade de Ciências e Tecnologia, Portugal

ABSTRACT

The work is focused on environmental degradation of bars of glass fiber reinforced polymers (GFRP) a type of

structural reinforcement (fib, 2007) often used in masonry (Tumialan and Nanni, 2002; Mohamed et al. 2012),

waterfront structures and bridges (Worner, 2015), and in special cases where steel may cause adverse operational

consequences. Uncertainties on service life of those rods under aggressive environmental conditions require further

data despite some existing literature on their durability. Those factors motivated an experimental program on the

effects of sorption of (i) salt water, with salinity 50g/l, and (ii) an alkaline solution (pH 13.6) on bars of GFRP,

including the study of protection given by concrete cover since rods are usually embedded. Diffusion of

contaminants was modeled and changes on chemical composition and on the transition vitreous temperature (Tg)

of resin, and on porosimetry of concrete mortar were examined. Redistribution and progressive reduction of the

number of larger pores with aging was detected, though causing little effect on porosity, with salt water found

more influential than the alkaline solution. Modification of Tg was negligible. Microscopic electronic scanning

(SEM) confirmed damage concentration on the matrix, and mostly in the peripheral region of rods. Alterations of

proportion of chemical elements were summarized and examined. Interpretation and correlation of data shed light

on mechanisms of failure of structural members reinforced with GFRP bars.





EFFECTS OF FIBER ARCHITECTURE ON FLEXURE PROPERTIES OF

PULTRUDED GFRP PLATES AND SECTIONS

Tianqiao Liu1, Kent A. Harries1,2 and Qi Guo1

1University of Pittsburgh, Civil and Environmental Engineering, Pittsburgh, USA ([email protected])

2University of Bath, BRE Centre for Innovative Construction Materials, Bath, UK

KEYWORDS

All FRP and smart FRP structures; Material Characterization of FRP and FRC materials/systems; Codes, Standards

and Design Guidelines; Fiber and Matrix Architecture

ABSTRACT

Flexural properties of pultruded glass fibre reinforced polymer (pGFRP) materials vary considerably and, unlike

longitudinal properties, are affected by fibre architecture which, itself, is typically a function of plate thickness.

Thin plates may have only a single longitudinal glass roving located near the plate midline while thicker plates

will have multiple rovings arranged at a distance from the midline. As a result, thicker plates will be

disproportionately stiffer and stronger in their flexural response than thinner plates. While the rule of mixtures is

appropriate for assessing axial and shear properties, additional information on the fibre architecture is required to

assess flexural properties which the rule of mixtures alone will overestimate. Variation of the location of the roving

through the plate thickness will also significantly affect longitudinal flexural properties. Thus the authors argue

for a member stiffness approach: determining flexural stiffness as the product of modulus and moment of inertia

(EI) rather than determining E and I separately. The paper presents a parametric study of idealised plate geometry

that demonstrates the impact of fibre architecture and that the rule of mixtures formulation results in an upper

bound solution for stiffness. Subsequent experimental and imaging data is presented that illustrates the significant

variation of fibre architecture and its effect on the flexural stiffness of the plate. Conclusions and recommendations

are made having direct relevance to ongoing international pGFRP design standards development.




FATIGUE AND DURABILITY OF LAMINATED CARBON FIBRE REINFORCED

POLYMER STRAPS FOR BRIDGE SUSPENDERS

Fabio Baschnagel1, Giovanni Pietro Terrasi1, Zafiris Triantafyllidis2, Urs Meier 3

1 Mechanical Systems Engineering Lab, Empa, Dübendorf, Switzerland; 2 IIE, The University of Edinburgh,

Edinburgh, UK; 3 Director emeritus, Empa, Dübendorf, Switzerland

KEYWORDS :

New composite materials, systems and strengthening techniques; Fatigue ; Characterization of FRP and FRC

materials/systems; Durability, long-term performance; CFRP tensile elements; bridge suspenders

ABSTRACT:

Steel cables and suspenders in bridges are at high risk of corrosion-fatigue and in some cases of fretting-fatigue in

their anchorages. These factors greatly limit the service stresses of a specific cable system and involve expensive

corrosion and fretting protection measures. The fretting fatigue behaviour of novel pin-loaded carbon fibre

reinforced polymer (CFRP) straps was studied as models for corrosion resistant suspenders of half-through arch

bridges. Two types of straps were tested: small model straps and large full-scale straps. In a first phase, ten fully

laminated and carbon pin-loaded CFRP model straps were subjected to an ultimate tensile strength test. Thereafter,

and in order to assess the durability, 29 model straps were subjected to a fretting fatigue test, which was

successfully passed by ten. An S-N curve was generated for a load ratio of 0.1 and a frequency of 10 Hz, showing

a fatigue limit of the straps around the epoxy matrix fatigue limit strain, corresponding to nearly half the ultimate

tensile strength of the straps. The fatigue limit was defined as 3 million load cycles (N = 3×106), but tests were

even conducted up to N = 11×106. In a second phase, one full-scale strap was tested for its ultimate tensile strength

and two full-scale straps were fatigue tested. In all tests, catastrophic failure of the straps was initiated in their

vertex areas. The influence of the fatigue testing on the straps’ residual mechanical properties was also assessed

for both strap types and although fretting fatigue represents an important limitation for laminated CFRP straps, it

could be shown that the investigated CFRP tension members can compete with the well-established steel

suspenders.

Corresponding author’s email: [email protected]

Figure 1 : Picture and illustration of the test setup of the model straps (left) and picture of a full-scale bridge

hanger before testing.




GLASS–GFRP HYBRIDS: FROM BRITTLE GLASS TO DUCTILE AND HIGH

STRENGTH STRUCTURAL GLASS

Mithila Achintha 1*, Bogdan Balan 1, Mikhail Bessonov 1, Tudor Zirbo 1, Jesmer Kanvar 1

1 University of Southampton, University of Southampton, Southampton, UK

(* corresponding author: [email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; Characterization of FRP

and FRC materials/systems; Bond and interfacial stresses ; Glass; Joints

ABSTRACT:

This paper presents selected findings from a research programme that aimed to exploit the use of externally-bonded

Glass Fibre Reinforced Polymer (GFRP) laminates as a mean of improving strength and ductility of glass

structures. Despite the potential of glass for delivering energy efficient buildings, brittle material behaviour and

the low tensile strength of glass pose major challenges when constructing facades and load-bearing structural

members. In particular, inefficiency of connections, where stress concentrations present and most likely to trigger

brittle failure, is the main difficulty compared to other construction materials, such as concrete and steel.

In the first half of the paper, using the results of a combined experimental/numerical investigation on the load

response and failure behaviour of glass–GFRP hybrid beams, it is shown that strong and ductile structural members

can be made from annealed glass. The hybrid beams consist of glass strips that are bonded to prefabricated GFRP

sheets by means of structural adhesives is a novel, yet a simple concept, but it has potential to initiate a radical

shift in the role of annealed glass in buildings: from its conventional use as inefficient infill panels, to structurally

efficient components in a robust structure.

The paper also shows that stress concentration features in glass such as bolted joints can sustain higher loads, even

after microcracks form, if the joint is reinforced with adhesively-bonded GFRP laminates. The efficacy of GFRP

reinforcement in increasing the load capacity and the ductility of bolted joints in tensile test specimens is presented.

The results show that bonded GFRPs have potential to strengthen joints in glass by either arresting the cracks

developed in the critical zone or eliminating the failure from the vicinity of the joint area. It is anticipated that the

findings of this study could be effectively used to develop reinforcement strategies for joints in glass.




INFLUENCE OF CURING CONDITIONS ON THE MECHANICAL BEHAVIOR OF

GLUED JOINTS OF CARBON FIBER REINFORCED POLYMER COMPOSITE /

CONCRETE

Anh Tuan LEE1, Marie MICHEL1, Emmanuel FERRIER 1

1 LMC2, Université LYON 1, Villeurbanne France

KEYWORDS :

All FRP and smart FRP structures; Experimental study ; Characterization of FRP and FRC materials/systems;

Bond and interfacial stresses; Glass transition; curing

ABSTRACT:

Polymeric adhesives are widely used in the case of the bonding of CFRPs on concrete structure. Indeed, structural

reinforcement by FRP is a very efficient method thanks to the high mechanical characteristics of the FRP and to

the implementation methods which make it possible to reduce work times. This method of reinforcement is carried

out on site on reinforced concrete supports which must be prepared before the reinforcement is applied. Working

on site assumes that the conditions for implementation are highly dependent on climatic conditions. However the

temperature and humidity conditions are likely to affect the mechanical and physical properties of the epoxy

polymers. Indeed, the hardeners used are of polyamide type hardening at ambient temperature. This leads to

composites whose mechanical and physical properties can be highly dependent on the curing time and its

temperature.

The paper presents an experimental study to highlight the impact of the application temperature on the behavior

of composite reinforcement. The objective is to analyze the mechanical and physical behavior of epoxy polymers

used for reinforcement by measuring on one hand the mechanical properties of composite adhesion on concrete

support by means of a double-shear and pull-out test and on the other hand, glass transition temperatures Tg. The

Tg measurements are carried out by DSC and TMA. Double shear tests results consist on establishing the laws of

local behavior in shear of composite / concrete adhesive joints according to the nature of the polymers and the

curing conditions. The shear-slip local bonding laws are identified by inverse method and are compared to the

analytical model available in the literature. The tests make it possible to determine the charge transfer lengths (Le)

and to evaluate the influence of the curing conditions on the value of this length. The physical measurements of

Tg support the study by specifying the influence of the curing conditions on these properties.

Figure 1 : mechanical and physical characterizations of glued joints

Angle Midpoint - 35,76 °C

Onset - 32,86 °C


Onset - 32,99 °C

Angle Midpoint - 51.40 °C

Onset - 44,48 °C


Onset - 61,28 °C

curing = 14j - 10°C

curing = 14j - 20°C

TG - DSC

RESIN 1curing = 14j - 40°C

curing = 14j - 5°C

-2,0

-1,5

-1,0

-0,5

0,0

0,5

Heat

flow

mW

Temperature °C25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

^ exo

S TARe SW 15.01ME TTLER TOLEDO




BEHAVIOR OF CFRP STRANDS EXPOSED TO SEVERE ENVIRONMENTAL

CONDITIONS

Omar Khalafalla 1, Sami Rizkalla 1, Adel ElSafty 2, Mohammad Pour-Ghaz 1

1 North Carolina State University, Department of Civil, Construction and Environmental Engineering, USA.

2 University of North Florida, College of Computing, Engineering and Construction, USA.

KEYWORDS

Carbon Fiber Reinforced Polymer, Composites, Durability, Prestressed Concrete, Sustained load effects.

ABSTRACT

Fiber reinforced polymer materials are becoming widely used as a primary reinforcement for concrete structures

due to their high strength and non-corroding characteristic, therefore, providing an alternative to steel

reinforcement. Degradation of FRP mechanical properties may occur due to environmental factors such as

moisture and alkalinity or physical effects such as sustained loading and fatigue. The synergistic effects of

environmental and mechanical loading has not been thoroughly studied which lead to a conservative design

process. Understanding the synergistic effects on the degradation of FRP leads to a more economic design and a

better prediction of the long-term performance of concrete structures.

This paper describes a comprehensive research undertaken to study the durability of CFRP prestressing strands

used for concrete bridge girders. The main objective of this research is to understand the effect of severe

environmental exposure and sustained loads on the mechanical properties of CFRP prestressing strands. The first

part of this research focuses on quantifying the possible degradation of CFRP strands under simultaneous sustained

loading and exposure to high alkali solution at elevated temperature. The second part, examines the structural

performance of CFRP strands used as pretensioning strands in reinforced concrete beams. The third part, focuses

on understanding the durability of constituent materials of CFRP strands.




INCREASING THE MECHANICAL EFFICIENCY OF PIN-LOADED STRAPS USING

THE SLING ANCHORAGE METHOD

Bernd Zwingmann1, Yue Liu 2, Mike Schlaich 2, Steffen Janetzko 3

1 schlaich bergermann partner sbp GmbH, Germany; 2 Berlin Institute of Technology, Department of

Conceptual and Structural Design, Germany; 3 SGL Carbon GmbH, Germany;

[email protected]

KEYWORDS :

All FRP and smart FRP structures; Experimental study ; Prestressing with FRP composites

ABSTRACT:

Pin-loaded straps are CFRP tension members typically anchored with laminated loop anchorages. A loop

anchorage is a very lightweight force locking anchorage, but its mechanical efficiency is limited to 70 % of the

tension member’s breaking load. At the pin, the laminated loop anchorage is exposed to high stresses caused by

the superposition of tension stress, bending stress and lateral compression. A new design is proposed for anchoring

pin-loaded straps called the sling anchorage. The sling anchorage provides a mechanical efficiency of 100 %. The

high mechanical efficiency of the sling anchorage is achieved by increasing the tension member’s cross section

locally at the anchorage.

The mechanical efficiency of the sling anchorage was predicted using the orthotropic tube model. By applying this

model, it was proven that the mechanical efficiency of the sling anchorage is higher than that of the loop anchorage.

Analytical analysis showed that the increased cross section reduces the average tension stress providing reserve

capacity for additional bending stress. Numerical analysis was used to compare the mechanical behaviour of the

loop anchorage and the sling anchorage. The results show that the location or fibre fracture was moved from the

inside to the outside of the anchorage. The stress in the sling anchorage was calculated to be significantly lower

for the same load.

The innovative fibre layout of the sling anchorage is achieved by alternately overlapping the ends of CFRP profiles

to form the loop shape. This method was used to produce sling anchorage prototypes. CFRP lamellas with

thermoplastic matrix were welded as defined by the sling anchorage fibre layout. Static tension tests were

conducted to characterise the load bearing behaviour of the sling anchorage prototypes. The experimental results

showed that the sling anchorage can achieve a mechanical efficiency of 100 %.

Figure 1 : Fibre layout of a loop anchorage and a sling anchorage




EFFECT OF INTERNAL MOISTURE CONTENT ON THE TG VALUES OF CFRP

RODS

Eleni Toumpanaki1, Janet M. Lees2, Michel Barbezat3 and Giovanni P. Terrasi4

1 University of Cambridge, Department of Architecture, Cambridge, UK; 2 University of Cambridge,

Engineering Department, Cambridge, UK; 3,4 Swiss Federal Laboratories for Materials Science and Technology

(EMPA), Laboratory for Mechanical Systems Engineering, Dübendorf , Switzerland

(Eleni Toumpanaki: [email protected])

KEYWORDS :

CFRP, DMA test, Material Characterisation, Environmental Conditions

ABSTRACT:

DMA tests are used for the material charaterisation of CFRP tendons for civil engineering applications and to

assess the high temperature behavior of CFRP prestressed structures by measuring the glass transition temperature

Tg. The glass transition temperature is sensitive to the moisture content of the CFRP tendons and standard test

methods (e.g. ASTM D7028 (ASTM 2007)) have not yet qualitatively addressed the effect of small moisture

content variations arising from environmental conditions on Tg values. The effect of the internal moisture content

on the Tg values of two CFRP rods with different diameters and manufacturing processes is evaluated. Lab

conditioned specimens (group D) with varying drying times (9, 15, 36 and 210 days) and thus moisture contents

are tested to study the effect of small variations in lab conditions on the measured glass transition temperature and

the sensitivity of the DMA testing. Specimens exposed at 60°C for roughly 3 years (group C) are also investigated

to record the effect of an even greater moisture absorption on the Tg values. Two heating runs were conducted for

every test to differentiate post-curing effects and mass weight measurements were recorded before and after each

heating run. A linear relationship between the mass loss of the specimens due to drying under vacuum and during

the heating runs was observed (Figure 1). Post-curing effects could not be clarified even for the dry specimens.

The exposed specimens showed a reduction in Tg of 38°C that was reversible after drying. It is recommended that

the use of Tg values to infer the degree of curing should be carried out on dry specimens.

Figure 1: Tg-tanδ versus mass loss ΔΜ-Group D experimental series

REFERENCES:

ASTM (2007). “Standard Test Method for Glass Transition Temperature (DMA Tg) of Polymer Matrix

Composites by Dynamic Mechanical Analysis (DMA)”, ASTM D7028 − 07, West Conshohocken, PA.





EVOLUTION OF THE TENSILE RESPONSE OF UNIDIRECTIONAL HYBRID FRP

LAMINATES FABRICATED BY HAND LAY-UP METHOD: EXPERIMENTAL AND

ANALYTIC ASSESSMENT

Filipe Ribeiro1, José Sena-Cruz 2, Eduardo Júlio 1, Fernando Branco 3,

Fernando Castro 4

1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Portugal; 2 ISISE, Department of Civil

Engineering, University of Minho, Portugal; 3 ISISE, Department of Civil Engineering, University of Coimbra,

Coimbra, Portugal; 4 CT2M, Department of Civil Engineering, University of Minho, Portugal (corresponding

author: [email protected])

Keywords:

New composite materials, systems and strengthening techniques; hybrid effect, pseudo-ductility, analytical

modelling

ABSTRACT:

Hybridisation, i.e., the incorporation of two different types of fibres, namely low strain (LS) and high strain (HS)

fibres, within the same polymeric matrix is an established approach to promote the appearance of a gradual and

non-fragile tensile failure mode of unidirectional Fibre Reinforced Polymers (FRP). This behaviour is known as

pseudo-ductile. In addition, hybridisation can increase the apparent strain at the failure of LS fibres. This

phenomenon has been described as “hybrid effect”.

In the present work, the tensile behaviour of 10 layer-by-layer unidirectional hybrid combinations has been

investigated using both experimental testing (see Figure 1) and analytical modelling. All the hybrid FRP samples

were made through the hand lamination of three different commercially available dry unidirectional fabrics

manufactured for civil engineering applications, namely high-modulus carbon (CHM), high-strength carbon (C)

and E-glass (G). For each type, a large number of single fibres were randomly taken from the dry fabrics and tested

in tension to define the Weibull distribution parameters, as shown in Figure 1.

100

150

50

50

15

Gau

ge

len

gth

Tab

s

Hybrid

composite

specimen

Clip

gauge

Grips 40

20

20

10

Glue

Fibre

Paper

frame

Grip





(a) (b) (c) (d)

Figure 1: Tensile tests: (a) geometry of composite specimen; (b) illustration of the composite test; (c) geometry

of single fibre specimen; (d) illustration of the single fibre test (dimensions in mm).

In the two tested hybrid combinations that included HM carbon as LS material (2G/1CHM/G, 1G/1CHM/1G),

pseudo-ductile tensile responses with fragmentation and dispersed delamination were achieved, as shown in Figure

2. In the same figure the number before letters in series ID shows the number of layers. In these combinations, the

mean yield stress varied between 732.6 and 768.2 MPa and the pseudo-ductile strain between 1.2% and 1.4%. An

analytical model presented in literature allowed to predict all the failure modes successfully. In this way, the

presented work validated the developed model for the set of materials and fabrication method used.

The hybrid effect varied between -14.1% and 27.7%. It was demonstrated that progressive damage model (PDM)

is a simple model that if used with care can predict reasonably the hybrid effect. However some limitations should

be taken into account. For instances, it does not take into account the real number of fibres leading that scale effects

to be ignored. Furthermore, it ignores the dispersion of fibres, which has been shown to be a very important

parameter for the hybrid effect.

(a) (b)

Figure 2: Typical example of pseudo-ductile tensile response: (a) 2G/1CHM/2G and (b) 1G/1CHM/1G.




NOVEL CAPACITIVE CFRP SENSOR FOR STRUCTURAL HEALTH

MONITORING

J. Yan 1, S. Hassan 1, A. Chen 1 and S. Laflamme 1 1 Department of Civil, Construction and Environmental Engineering, Iowa State University, USA

(corresponding author: [email protected]).

ABSTRACT

Carbon Fiber-Reinforced Polymer (CFRP) is widely used in strengthening, rehabilitating and retrofitting of

existing structures because of its ease and speed of construction, low maintenance requirement, and high strength-

to-weight ratio. The objective of this study is to employ CFRP as a multifunctional material for both strengthening

and Structural Health Monitoring (SHM). The authors have developed a capacitive-based CFRP sensor, which

consists of two CFRP layers separated by a dielectric layer. Damage can be detected through a variation in the

sensor’s capacitance provoked by the strain. This design utilizes the advantages of CFRP, including high corrosion

resistance, weak thermoelectric behavior, and high electrical conductivity. Such multi-functional CFRP is

particularly suitable for applications to civil structures because of its capability to both strengthen and monitor a

structure. This paper investigates the use of titania dispersed in the epoxy layer separating the CFRP layers to

enhance the strain sensitivity of the sensor. Electromechanical experiments are conducted on tension specimens to

demonstrate the capability of utilizing the change in electrical signal to measure strain.




EMBEDDED PIEZO MICRO-PATCHES FOR CURE MONITORING OF FIBER-

REINFORCED EPOXY IN CIVIL ENGINEERING REPAIRS

Olivier Bareille1, Michelle Salvia 1, Fernanda Benezra-Maia 2

1 Ecole Centrale de Lyon, LTDS CNRS UMR 5513, Université de Lyon, France;

2 Federal University of Rio Grande do Sul, Department of Civil Engineering, Brasil

KEYWORDS :

All FRP and smart FRP structures; ; Inspection, NDT methods and quality assurance; Characterization of FRP

and FRC materials/systems

ABSTRACT:

In recent years high interests of maintenance and repair of civil structures were concentrated on the use of natural

fiber or carbon fiber reinforced thermosets as structural component. The thermosets were mainly room temperature

curing bio-based epoxies. The properties of the resulting mechanical composites are directly in relation to

reinforcement type but also to viscoelastic matrix properties and reinforcement/matrix interactions.

The most important factor which can control the properties of the matrix and of the reinforcement-matrix interface

is in particular the cross-linking density resulting from the manufacturing process that is linked to the degree of

cure. The cure of a thermoset is a complex process which leads to a three-dimensional macromolecular network.

The final morphology of the three-dimensional network, which determines the properties of the material, depends

on this transformation. So, there is a growing need for sensors, which provide real-time, in situ monitoring of the

manufacturing process. This study, in the frame of a collaborative research (MICRO ANR project), proposes to

in-situ follow-up the cure mechanism of an epoxy-amine resin using piezoelectric elements embedded in the

composite structure at different locations. The technique used in this work is based on the measurement of the

electrical impedance of piezoelectric ceramics. The change in the impedance spectrum which is linked to the

changes of matrix viscoelastic properties as cure progressed is used to understand the different steps of the epoxy

cure regarding molecular motion, viscosity, density and their consequences on the mechanical properties of the

material.

Moreover, after curing, the sensor may be used as damage detector and wear sensor. In order to assess the

efficiency of such a system and especially the optimal placement of the set of piezopatches for both curing

observance and health monitoring, tests were performed based on three-point bending measurements and scanning

electron microscope.




DYNAMIC TENSILE PROPERTIES OF POLYETHYLENE TEREPHTHALATE

FIBER BUNDLE WITH LARGE DEFORMABILITY

Y.L. Bai 1, Z.W Yan 1, J. G. Dai 2, D. J. Zhu 3, Q Han 1, X.L. Du 1

1 Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,

Beijing University of Technology, China.

2 Department of Civil and Environmental Engineering,

The Hong Kong Polytechnic University, China.

(corresponding author: [email protected].)

3 College of Civil Engineering, Hunan University, China

KEYWORDS :

Strain rate; Dynamic tensile mechanical properties; Weibull analysis; Polyethylene terephthalate

ABSTRACT:

In this paper, strain rate effects on the tensile mechanical properties of Polyethylene Terephthalate (PET) fiber

bundles at room temperate were studied. First of all, an MTS load frame together with an Instron drop-weight

impact system were used to carry out the tensile test under the quasi-static (1/600s-1) and the dynamic loadings

(40, 80, 120 and 160s-1), respectively. The dynamic mechanical properties, consisting of the tensile strength, peak

strain, elastic modulus and toughness, were analyzed based on the test data. It was concluded that the tensile

strength increases with strain rate while the peak strain and toughness decrease with the strain rate. The initial

elastic modulus remains almost unchanged at the low strain rate (no more than 40s-1) and starts to grow when the

strain rate is beyond 40s-1. The second-stage elastic modulus rises continuously with the strain rate from 1/600 to

160s-1. Afterwards, the dynamic tensile strength of a PET fiber bundle was statistically analyzed by using the two-

parameter Weibull distribution model that can help to quantify the scatter of the dynamic tensile strength. The

corresponding parameters can be added into a numerical simulation in future to reflect the different tensile strength

caused by defects.





INTERFACIAL ADHESION STUDY ON EPOXY PREPREG MODIFIED WITH HIGH

POLY(CARBONATE) LOADING

Utai Meekum* and Waree Wangkheeree aInstitute of Design Technology, Suranaree University of Technology, Maung, Nakorn Ratchasima, THAILAND

*Corresponding author: [email protected]

KEYWORDS:

Interfacial shear strength, prepreg epoxy, Poly(carbonate), epoxidized natural rubber and multiwall carbon

nanotube.

ABSTRACT

The interfacial adhesion strength of the in-house prepreg epoxy formulation modified with poly)carbonate()PC(,

50% by mole epoxidized natural rubber)ENR50( and multiwall carbon nanotube)MWCNT( were studied. In the

modification of prepreg epoxy matrix formulation with PC at 0 – 80 phr, the interfacial shear strengths showed the

tendency to be decreased with increasing the PC loading. The added PC had caused the low surface energy, the

constrain in resin infusion/impregnation into fiber due to absolute high viscosity, crack tip sensitive of added PC

and inferior in chemical inter locking due to the low network density; retarded by the transesterification and/or

cyclization. Those hypothesizes were the main justification for the interfacial strength inferiority. Attempting to

enhance the interfacial adhesion by mixing the ENR50 into 30 phr PC modified prepreg epoxy matrix was also

found ineffective. The adhesion strength was obviously decreased with increasing the ENR50 loading. The similar

hypothesizes with the additional of the rubber phase separation phenomenon were taken for explanation. The

interfacial adhesion strength enhancement was achieved by modification the prepreg epoxy formulations by adding

MWCNT nanofiller at the concentration not exceed 0.3 phr. The agglomeration of the nanofiller was observed at

the critical loading at 0.5 phr. It was suspected for the fiber/matrix adhesion ineffectiveness.





TWO-DIMENSIONAL DELAMINATION IN GFRP LAMINATES: EXPERIMENTAL

INVESTIGATION

Aida Cameselle-Molares1, Anastasios Vassilopoulos1, Thomas Keller 1

1 Ecole Polytechnique Fédérale de Lausanne (EPFL), Composite Construction Laboratory (CCLab), Lausanne,

Switzerland

KEYWORDS :


Characterization of FRP and FRC materials/systems; Fracture; 2D crack propagation

ABSTRACT:

The 2D delamination behavior of composite laminates under quasi-static out-of-plane opening loading has been

experimentally investigated. A new design and experimental set-up for square GFRP/epoxy plates have been

developed. A circular embedded pre-crack was introduced in the center and at the midplane of the laminate and

the load was introduced by means of thin steel sheets also embedded in the laminates and in-house developed

piano hinges. In order to investigate the effect of the fiber architecture on the fracture behavior, three different

types of isotropic and orthotropic fabrics were selected. Increasing load-displacement curves were obtained as a

result of an increasing crack front length during propagation. During the loading process, stiffening and softening

mechanisms were activated. The stretching of the delaminated laminates, in both the radial and circumferential

directions, constituted the main stiffening mechanism that appeared and increased as the plate opened. Once the

crack started growing, a corresponding softening due to crack propagation occurred together with a secondary

stiffening mechanism, fiber bridging. All these stiffness-related mechanisms were reflected in the compliance,

initially exhibiting a descending branch where the stiffening mechanisms prevailed and increasing only when the

softening due to crack propagation became the dominant mechanism.

Figure 1: Description of assembling of loading system; dimensions in mm




Figure 2: Experimental set-up and instrumentation layout

Figure 3: Example of load and crack length vs opening displacement curves

Figure 4: Example of deformation in one of the plates




RELAXATION OF FRP MATERIALS – ISSUE OVERVIEW IN THE AVAILABLE

LITERATURE, CODES AND GUIDELINES

Marta Przygocka1, Renata Kotynia 1

1 Lodz University of Technology, Department of Concrete Structures, Lodz, Poland; (corresponding author:

[email protected])

KEYWORDS

All FRP and smart FRP structures; prestressing with FRP composites; Material; Standard; relaxation; durability;

rheology

ABSTRACT

Use of FRP (fiber reinforced polymer) materials for reinforcing and strengthening of RC structures with

simultaneous prestress results in the increase of load carrying capacity of RC members and the improvement of

serviceability limit state conditions. The main issue affecting the durability of prestressed construction are

prestressing losses. The general division of prestressing losses distinguishes immediate losses, which appear

immediately after the termination of the prestressing and delayed losses increasing with time of occurrence of

phenomena that cause them. The immediate prestressing losses are caused by different factors in dependence of

the prestressing technique: friction, relaxation of the FRP material, temperature and elastic shortening of concrete.

Delayed prestressing losses consists of creep, shrinkage and relaxation. The overview of experimental tests

described in the available literature considering the relaxation of FRP materials is presented herein. According to

experimental results the relaxation of FRP materials is affected by different factors as insolation, temperature and

humidity. The review of test methods for long-term relaxation of FRPs with the description of geometry of

samples, anchorage details for different types of tendons (circular, flat), duration of tests and frequency of

measurements in available codes and guidelines is also presented.




BEHAVIOR OF GFRP BARS IN SEAWATER-CONTAMINATED CONCRETE

SUBJECTED TO SUSTAINED LOADING

Hilal El-Hassan1, Tamer El-Maaddawy1, Abdelrahman Al-Sallamin1

1 UAE University, Department of Civil and Environmental Engineering, Al Ain, United Arab Emirates

(corresponding author: [email protected])

KEYWORDS:

All FRP and smart FRP structures; Experimental study; Durability, long-term performance; Characterization of

FRP and FRC materials/systems

ABSTRACT:

In recent years, there has been an increasing interest to replace steel reinforcement in concrete by non-corrosive

material to alleviate corrosion-related problems. Glass fiber-reinforced polymer (GFRP) bars are advocated as a

potential alternative, owing to their superior physical and mechanical properties. Though, the acceptance of these

materials by the construction industry is critically dependent on their long-term performance. This paper

investigates the durability behavior of GFRP bars embedded in moist seawater-contaminated concrete under a

sustained load of 25% of its ultimate tensile stress. Samples were conditioned for 10 months at temperatures of

20, 40, and 60°C and then retrieved for uniaxial tensile testing. However, GFRP bars conditioned at 60°C

experienced creep-rupture during conditioning. As such, tensile strength retentions were measured for non-creep-

ruptured bars only as a means to evaluate the long-term durability of GFRP. The microstructure of creep-ruptured

specimens was characterized by employing scanning electron microscopy, Fourier transform infrared

spectroscopy, and differential scanning calorimetry. Research findings showed that an increase in conditioning

temperature from 20 to 40°C led to a decrease in tensile strength retention from 90 to 73% due to accelerated

diffusion of water and, consequently, a higher moisture uptake. At a higher conditioning temperature of 60°C,

microstructure analysis highlighted development of hydroxyl groups, plasticization and chemical degradation of

the matrix, and deterioration of the fiber-matrix interface (see Figure 1). In comparison to unloaded, conditioned

GFRP samples, the presence of a sustained load promoted tensile strength loss and degradation of GFRP bars.

Nevertheless, this detrimental effect was more prominent at elevated temperatures.

(a) (b)

Figure 1: SEM micrographs of GFRP bar conditioned for 9.6 months at 60°C under sustained load: (a) cross-

sectional (b) longitudinal





ENVIRONMENTAL DURABILITY OF HAND-LAYUP CARBON/EPOXY

COMPOSITES INTENDED FOR STRENGTHENING OF CONCRETE

STRUCTURES

Wendlamita Zombré1, Robert Chlela2, Marie Michel1, Julien Mercier3, Karim Benzarti2, Laurence Curtil1 1 University of Lyon, University Lyon 1, LMC² (EA 7427), France, Email: [email protected]

2 University Paris-Est, Laboratory Navier (UMR 8205), IFSTTAR, France 3Freyssinet International, France

KEYWORDS

Strengthening and repair; Durability study; Long-term performance; Mechanical characterization, CFRP

Composites; Hydrothermal Ageing.

ABSTRACT

In the framework of a project funded by the French National Research Agency (ANR), which is called MICRO, a

large-scale durability study is currently being conducted on composite materials intended for strengthening

applications on building or civil structures. This paper aims at presenting the first results of accelerated ageing

tests performed on carbon fiber reinforced polymer (CFRP) laminates made by wet lay-up process, and on CFRP

strengthened concrete slabs. The experimental test program consists in subjecting the various specimens (CFRP

laminates and strengthened concrete slabs) to six different hydrothermal environments, obtained by combining 3

temperature conditions (25°C, 50°C and 60°C) and 3 relative humidity levels (50%, 75% and 100% RH under

total immersion). Mechanical characterizations are periodically carried out on aged specimens to monitor their

evolutions in terms of tensile performances and interlaminar shear properties (for CFRP laminates), and in terms

of adhesive bond properties (through pull-off tests on concrete/CFRP assemblies). Changes in these performance

indicators are then correlated with each other, and with water mass uptake as well. A correlation between water

uptake and exposure temperature has been established, revealing the dependence of ageing kinetics upon

temperature. It is also showed that when the conditioning temperature is higher than the initial glass transition

temperature of the unaged specimens, post cure phenomena occur and lead to an increase in the cohesion of the

fiber/matrix interface, together with a slight decrease in the residual performances of the CFRP laminates. In the

end, conclusions are drawn regarding links between the selected key performance indicators and mass uptake.

Collected data provide a better comprehension on the hydrothermal ageing mechanisms of CFRP laminates and

their adhesive bond with concrete, and will be used at a further stage to develop predictive models for reliability

and service-life assessment.

Figure 1: Evolution of the water uptake for CFRP laminates subjected to the various ageing conditions.





ASTM SPECIFICATION FOR GLASS-FIBER REINFORCED POLYMER BARS

FOR CONCRETE REINFORCEMENT

R. Gentry 1 and C. E. Bakis 2

1 Georgia Institute of Technology, School of Architecture, Atlanta, GA 30332 USA

Email: [email protected]

2 Pennsylvania State University, Engineering Science and Mechanics, University Park, PA 16802 USA

KEYWORDS

Codes, standards, FRP internal concrete reinforcement, GFRP

ABSTRACT

A major barrier to the acceptance of FRP composite materials in civil engineering is the lack of standard materials.

Non-standard and proprietary materials must be qualified for short- and long-term performance, using test

methods and meeting requirements that may also lack standardization. In North America, ASTM D30.10 –

Composites for Civil Structures, develops test methods and material standards for FRP materials. This paper

reports on the recently approved ASTM Standard for Solid Round Glass FRP Bars for Concrete Reinforcement.

The standard covers requirements on constituent materials, bar geometry and testing for physical, mechanical and

durability properties. The paper outlines the material specification, introduces the dependent test methods that

support the specification, and discusses possible future standardization efforts for FRP bars in ASTM D30.




PREDICTION OF TENSILE STRENGTH OF FRP CABLE CONSIDERING

RANDOM STRENGTH DISTRIBUTION

Z. Q. Peng1, L. N. Ding2, X. Wang1 and Z. S. Wu1

1 National and Local Unified Engineering Research Center for Basalt Fiber Production and Application

Technology, International Institute for Urban Systems Engineering, Southeast University, Nanjing 210096,

China, E-mail: [email protected]

2 School of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China.

ABSTRACT

Fibre-reinforced polymer (FRP) cables have been developed as advanced materials to substitute steel cables for

their light weight, high strength, and high resistance to corrosion. In this paper, a finite element model was

established to predict the tensile strength of the cable component FRP tendon considering random strength

distribution. The influence of initial curvature of fibre yarns was particularly discussed, and simulated results

showed that curvature had neglectable effect on tensile strength but significant influence on coefficient of variation

of strength. The predicted ultimate strength and strain of the tendon based on the proposed model achieved good

consistency with the experimental results, which provides an efficient method for further study on members and

structures regarding FRP cables.




Eco composite or bio sourced composites materials




FATIGUE PERFORMANCE OF BIORESIN GLASS FIBRE REINFORCED

POLYMERS

A. Watfa 1, M. F. Green 2 and A. Fam 2

1 Queen’s University, Department of Civil Engineering, Kingston, Canada,


2 Queen’s University, Department of Civil Engineering, Kingston, Canada.

KEYWORDS :

All FRP and smart FRP structures; Fatigue ; Durability, long-term performance; Characterization of FRP and

FRC materials/systems; Bioresin; GFRP.

ABSTRACT:

Fatigue performance of glass fibre reinforced polymers (GFRPs) is critical for applications for wind turbine towers.

Substantial experimental fatigue data is available for GFRPs with epoxy, polyester, and vinylester matrices.

However, the cyclic behaviour of GFRP with bioresins is a new research area and little information is available.

This paper investigates the fatigue behaviour of unidirectional GFRPs fabricated with a bioresin matrix for wind

turbine tower applications.

Seventeen single layer GFRP specimens (36 % fibre volume fraction) are subjected to tension-tension cyclic

loading of varying loading stress ratio of R = 0.1 and R = 0.5 in constant amplitude load control with a loading

frequency of 2.5 Hz. At least twelve specimens are tested for each loading stress ratio. Additionally, two to three

specimens are considered at each maximum stress level for consistency purposes. Stress-life experimental data are

obtained for the single layer bioresin GFRPs. The S-N curves show that the tensile strength degradation of the

bioresin GFRP is 58% after 106 cycles for a stress ratio of 0.5. Two methods for the statistical analysis of

unidirectional bioresin GFRP fatigue data and the derivation of reliability-based S-N curves are also presented.





ILLUMINATED BIOBASED SANDWICH FACADE WITH NATURAL FIBRE

REINFORCED POLYMER AND CARDBOARD CORE

Carolin Petzoldt1, Ralf Gliniorz1, Andreas Ehrlich1, Sandra Gelbrich1, Lothar Kroll1

1Technische Universität Chemnitz, Institute of Lightweight Structures, Chemnitz, Germany

(email: [email protected]);

KEYWORDS:

Interactive FRP-structure; Characterization of FRP and FRC materials/systems; Eco-composite & bio-sourced

composite materials; Sandwich Element

ABSTRACT:

The building envelope as an integral part of buildings and renewable resources have a key role in energy

consumption. So the aim of the project was the development and implementation of a free forming facade system

from biobased materials with an integration of additional functions. The field of application is aimed in modern

architecture, like the office building "Fachagentur Nachwachsende Rohstoffe e.V." with its oak wood recycled

facade. The build-up of the sandwich contains face sheets from natural fibre reinforced polymer (NFRP), using

flax fibres and biobased epoxy resin respective pre-accelerated, filled polyester resin with excellent weather

resistance and no significant reduction in fire performance, and a stuck cardboard core structure. Furthermore a

formwork system was designed enabling biobased sandwich elements to be produced with special needs according

to efficiency and architectural design. As a result, the biobased and sustainable sandwich elements exhibit low

system weight, high sound reduction and sufficient load capacity for the use as facade elements. Additionally

LED-stripes were integrated for illuminating the facade elements. Because of the regular pattern of the stuck

cardboard core and the translucent face sheet laminates the facade works like a screen on which each created pixel

can be controlled in RGB-colours. Therefore an area of 10 m x 5 m biobased sandwich facade with 25 elements is

planned as a reference object in Chemnitz (Germany), forming a facade with 100 x 48 pixels. In summary the

illuminated biobased sandwich element produced with an efficient technology of production and with the use of

renewable resources can replace extensively 3D-formed customary facade systems.

Figure 1: Reference object in Chemnitz (left) and a model of the illuminated facade element (right)




EFFECTS OF CNF CONTENT ON MECHANICAL PROPERTIES OF FLAX FIBER

REINFORCED NANOCOMPOSITES

Yanlei Wang1, Baolin Wan2, Xiushui Yin3

1 Dalian University of Technology, School of Civil Engineering, Dalian, China; 2 Marquette University,

Department of Civil, Construction and Environmental Engineering, Milwaukee, USA; 3 (corresponding author:

[email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; Eco-composite & bio-

sourced composite materials; Carbon nanofibers (CNF); Flax fiber reinforced polymer (FFRP); Mechanical

properties; Nanocomposites; Scanning electron microscope (SEM).

ABSTRACT:

Flax fibers are widely grown materials which have short growth cycle, low density, high specific strength, and

high specific stiffness. Therefore, flax fiber reinforced polymer (FFRP) has potential to replace part of GFRP and

CFRP in engineering applications. Nanoparticles have large surface area and stable structure due to its small-scale

structure. They can form strong bond with resin. Therefore, adding nanoparticles to epoxy resin matrix can improve

the mechanical and thermal properties, and fire resistance of the composite material. Carbon Nano Fiber (CNF)

has a length in the order of micron while its diameter in the order of nano-meter.

In order to study the effect of CNF on the mechanical properties of epoxy resin and FFRP, different amounts of

CNF were dispersed in the epoxy resin matrix by using high-speed mechanical mixing, vacuum and ultrasonic

dispersion methods in this study. Direct tensile tests were performed to evaluate the tensile strength, modulus of

elasticity and elongation at break of the CNF modified epoxy and the flax fiber reinforced nanocomposites.

Scanning electron microscope (SEM) was also used to observe the CNF distribution in the epoxy resin matrix.

With the increase of the content of carbon nanofibers, both tensile strength and modulus of elasticity of the

nanocomposites increased first and then decreased as shown in Figure 1. However, all specimens with CNF had

larger tensile strength and modulus of elasticity than those of specimens with pure epoxy resin. The maximum

tensile strength and modulus of elasticity happened in the flax fiber reinforced nanocomposite with 0.5% of CNF

in epoxy resin by weight. The elongation of the specimens increased continuously with the increase of CNF

content. SCM images show that CNF dispersed more uniformly in the specimens with 0.5% of CNF than those

with 1.0% of CNF. This is the reason why the mechanical properties of the nanocomposites with 0.5% of CNF

were better than those with 1.0% of CNF.

(a) Tensile strength (b) Young’s modulus ( c) Elongation

Figure 1: Mechanical properties of FFRP with different contents of CNF.




BIOBASED EPOXY NETWORKS FOR CIVIL ENGINEERING APPLICATIONS

J. Galy, A. Viretto

Université de Lyon, INSA Lyon, Ingénierie des Matériaux Polymères (IMP-UMR 5223), 17 Avenue Jean

Capelle, 69621, Villeurbanne, France

[email protected]

KEYWORDS :

New composite materials, Epoxy, Biobased matrices

ABSTRACT:

Epoxy matrices are successfully used for structural strengthening in civil engineering applications by means of

carbon fibre reinforced polymers (CFRP). These high-performance materials have unique properties that make

them especially attractive for such applications — quick cure time, good mechanical strength, and ease of

processing. In the context of sustainable development, the aim of our study is to develop biobased epoxy matrices

as an alternative to the traditional petroleum-based epoxy matrices used in CFRP. The work presented here is part

of a much larger research study to develop ‘green composites’, where the use of flax or basalt fibres as reinforcing

fibres is investigated (ANR ‘micro’). We focus on two biobased epoxy monomers: a diglycidyl ether of bisphenol

A (DGEBA) and a sorbitol polyglycidyl ether (SPGE). These monomers were reacted with a biobased curing

agent, a phenalkamine (PhA), derived from cardanol. After in-depth characterisation of the chemical structures of

the three monomers, the reactivity of both systems, DGEBA-PhA and SPGE-PhA, was studied using DSC and

rheology. The properties of the networks were characterised via dynamic mechanical analysis and water uptake

measurements for networks with partial or full conversion of epoxy groups, which were obtained by crosslinking

at room temperature or at high temperature, respectively. The results reveal that the two systems are good

candidates for the preparation of green composite materials as they meet the requirements necessary for

manufacturing composites in civil engineering applications.

works cured at room temperature::

DGEBA – PhA, : SPGE – PhA.

ACKNOWLEDGEMENTS

Funding for this study was provided by ANR (Agence Nationale de la Recherche) through the contract ANR-15-

CE22-0007-04 - “MICRO: Matériaux Innovants Composites pour la Réparation d’Ouvrage”.




PHYSICAL AND MECHANICAL CHARACTERIZATION OF NATURAL FIBERS

AND FABRICS AS REINFORCEMENT FOR COMPOSITE SYSTEMS

Giuseppe Ferrara1, Bartolomeo Coppola 2, Luciano Di Maio 2, Enzo Martinelli1

1University of Salerno, Department of Civil Engineering, Fisciano (SA), Italy; 2University of Salerno,

Department of Industrial Engineering, Fisciano (SA), Italy; (corresponding author: [email protected]).

KEYWORDS :

Strengthening and repair; Experimental study; Eco-composite & bio-sourced composite materials; FRC and

cement composite materials; Flax fibres

ABSTRACT:

In the last years, the increasing interest toward more environmental friendly materials has focused the attention on

natural fibres and on their potential contributions in composite materials. Although several research activities have

shown the good mechanical properties of these fibres, their use is still limited due to both the absence of a standards

and guidelines and some open durability issues highlighted in the literature.

The present work is a contribution to identifying the main physical and mechanical properties of flax fibers and

fabrics intended as internal reinforcement in composite materials with mineral matrix. Due to the lack in

standardization on vegetable fibres as constituent of building materials, the experimental research moves from

characterising the geometry of bundles. The diameter of single yarn and twisted bundles has been measured by

means of a large number of measurements obtained by a microscope: specifically, six values have been recorded

for each one of thirty specimens. A comparison with a most accurate SEM analysis has been performed as well.

Tensile tests on single yarn, double yarn twisted bundle and textile strip specimens have been carried out. Tensile

test on flax textile have been performed after a specific curing period in controlled environment in order to evaluate

the durability of the textile and its sensitivity to alkali agents. A bidirectional grid flax textile have been embedded

in inorganic matrix obtaining a Textile Reinforcing Mortar composite system. Tensile tests on TRM specimens

have been performed to evaluate the efficiency of the use of natural fibres in such composite systems. The results

of the experimental activity showed that the diameter values assessed by means of microscope are affected by the

irregularities of the flax bundles, due to their twisted arrangement.

Figure 1 : Flax twisted bundle microscope image




EMPIRICAL DESIGN EQUATION TO PREDICT THE AXIAL LOAD CAPACITY OF

SANDWICH PANELS WITH FLAX FRP SKINS

M. Noël 1 and A. Fam 2 1 University of Ottawa, Ottawa, Canada, Email: [email protected]

2 Queen’s University, Kingston, Canada.

ABSTRACT

A new design approach is presented for predicting the axial strength of flax fiber reinforced polymer (FFRP)

sandwich panels which is calibrated using experimental results with consideration of different failure modes

including global buckling and localized failures. Use of natural fiber composite materials for construction is rapidly

gaining interest in response to the growing need to reduce consumption of non-renewable resources and the

embodied energy of buildings and infrastructure to meet sustainability and climate change initiatives. FFRP

materials in particular have shown potential as an alternative to glass fiber reinforced polymer (GFRP) composites

with similar mechanical properties for structural and semi-structural applications. Lightweight insulated FFRP

sandwich panels with polyisocyanurate foam cores present one such application which can be used in rapid

modular construction, cladding, or decking. The current study presents a new model for predicting the ultimate

axial strength of FFRP sandwich panels which has been calibrated using an experimental study comprised of 87

column specimens having cross-sectional dimensions of 100 x 50 mm that investigated the effects of slenderness

ratio (ranging from 22 to 62), FFRP skin thickness (one to five layers corresponding to core-to-skin thicknesses of

15 to 64), and foam core density (ranging from 32 to 96 kg/m3). The preliminary model presented agreed well with

experimental results with an experimental-to-predicted ratio of 0.98 and a COV of 0.18. Additional work is needed

to apply the model to other FRP skin types and core thicknesses.




HYGROTHERMAL AGEING OF FLAX FIBRE REINFORCED COMPOSITES

INTENDED FOR THE STRENGTHENING OF CONCRETE STRUCTURES

R. Chlela 1, W. Zombré 2, M. Quiertant 3, L. Curtil 2, and K. Benzarti 1

1 Université Paris-Est, Laboratoire Navier (UMR 8205), IFSTTAR, France, Email: [email protected]

2 Université Claude Bernard Lyon 1, Laboratory of Composite Materials for Construction (LMC2), France

3 Université Paris-Est, IFSTTAR, MAST-EMGCU, France.

ABSTRACT

The combination of natural fibres and a bio-based matrix to produce environmentally friendly composites for

structural strengthening applications in construction has been the subject of a significant amount of research.

However, a main drawback of natural fibres is their sensitivity to environmental conditions, which may affect the

mechanical properties of both the composite itself and its adhesive bond with the host structure in the long term.

The present durability study, conducted in the framework of the MICRO project funded by the French National

Research Agency (ANR), aims at investigating the influence of hygrothermal ageing on the mechanical

performances of an innovating composite strengthening system based on a bio-epoxy matrix reinforced by flax

fibres. The test program consists in subjecting composite laminates and strengthened concrete slabs to accelerated

ageing conditions, under six different combinations of temperature and humidity. Aged laminates are then

periodically characterized by tensile tests and interlaminar shear tests, while the bond properties of

concrete/composite assemblies are assessed by pull-off tests.

This paper presents the first results of this ongoing experimental program which is scheduled over a total period

of 2 years. Results are discussed in the light of complementary investigations (monitoring of the water sorption

behaviour, microscopic observations, and evaluation of the glass transition temperature by differential scanning

calorimetry – DSC) in order to relate the observed performance evolutions to actual microstructural changes or

damage processes taking place in the material during ageing.

KEYWORDS

Hygrothermal ageing, flax fibre reinforced polymer composites, bio-based epoxy matrix, tensile test, pull-off test,

water sorption.

Figure 1: Microscopic observations of polished cross-sections of FFRP laminates subjected to various ageing

conditions for 3 months.

20°C ; 50% 20°C ; 100% 40°C ; 100%

60°C ; 50% 60°C ; 75% 60°C ; 100%

50

µ

m

5

0

µ

m

5

0

µ

m

5

0

µ

m

5

0

µ

m




BASALT FIBER REINFORCED POLYMER (BFRP): AN INNOVATIVE

COMPOSITE TO REPAIR CONCRETE STRUCTURES?

Clément Lacoste1, Anne Bergeret 1

1 Centre des Matériaux des Mines d’Alès (C2MA), Alès, France (corresponding author:

[email protected])

KEYWORDS :

All FRP and smart FRP structures; Material ; Characterization of FRP and FRC materials/systems; Eco-

composite & bio-sourced composite materials

ABSTRACT:

Concrete structures could be modified under various environmental conditions (corrosion, fatigue or exceptional

loads) and need to be reinforced to extend their service life. A recent and popular technic have been introduced

with Fiber Reinforced Polymer (FRP). The reinforcement of concrete structure is achieved by hand lay-up of the

composite materials. Usually, Carbone Fiber Reinforced Polymer (CFRP) is the first commercial choice according

to their high tensile properties and durability. However, considering the need of lowering the delivery and

environmental cost of the composite materials, non-conventional innovative materials should be explored.

The promising nature, low cost and effective properties of basalt fibers could make basalt a prospective candidate

for reinforcement in FRP because of their good resistance to weather, alkaline and acids exposure. The usage of

natural fibers such as flax with interesting mechanical properties as replacement for inorganic fibers is also of

major interest. However, the non-structure application of this material still limited their development in FRP.

This study is focused on the development of basalt fiber reinforced polymer (BFRP) and its potential use for

concrete structures reinforcement. The development of a new type of hybrid composite, associating basalt and flax

fibers was also studied as well as surface treatments for flax fibers to improve their durability.

Figure 1: Basalt (left), flax (middle) and hybrid (right) fabrics reinforced epoxy composites




FRC and cement based composite materials




STRAIN AND CRACK DETECTION IN EXPERIMENTAL TESTS ON TEXTILE

REINFORCED MORTAR COMPOSITES

Marcin Tekieli1*, Stefano De Santis2, Gianmarco de Felice2, Łukasz Hojdys1, Piotr Krajewski1, Arkadiusz

Kwiecień1, Francesca Roscini2 1 Cracow University of Technology, Faculty of Civil Engineering. Warszawska 24, 31-155 Cracow, Poland; 2

Roma Tre University, Department of Engineering. Via Vito Volterra 62, 00146 Rome, Italy.

*corresponding author: [email protected]

KEYWORDS:

direct tensile tests, shear bond tests, crack pattern, full-field optical measurement technique, TRM, FRCM, strain

detection

ABSTRACT:

This paper presents the application of Digital Image Correlation (DIC) to the measurement of displacement and

strains and to the detection of crack pattern in tensile and bond tests on Textile Reinforced Mortar (TRM)

composites (Figure 1). DIC is a full-field contactless optical method for measuring displacements in experimental

testing, based on the correlation of the digital images taken during test execution. With respect to conventional

methods, DIC offers the advantageous possibility of selecting several measurement points after the test, is more

cost-efficient, does not entail any risks of damage to instrumentation, and is generally less affected by stroke or

encumbrance limitations. On the other hand, it detects only the outer surface of the specimen, so no information

is directly available on the textile that is embedded in the matrix, and requires particular care for setup preparation.

In this work, two DIC software programs were used and their results were compared to each other as well as to

those provided by traditional transducers for mutual validation. The advantages offered by DIC with respect to

conventional sensors, as a tool for improving the mechanical characterization of TRMs and for developing a deeper

understanding of their behaviour, are discussed together with some of its limitations.

Figure 1: TRM-to-substrate hear bond tests: crack pattern (a,b), and fields of vertical displacements (c) and

strain (d) recorded by DIC.




MECHANICAL CHARACTERIZATION OF MULTI-PLY STEEL REINFORCED

GROUT COMPOSITES FOR THE STRENGTHENING OF CONCRETE

STRUCTURES

Georgia E. Thermou1,2, Gianmarco de Felice3, Stefano De Santis3, Sultan Alotaibi1, Francesca Roscini3, Iman

Hajirasouliha1, Maurizio Guadagnini1

1The University of Sheffield, Civil and Structural Engineering Department, Sir Frederick Mappin Building

Mappin Street, Sheffield, S1 3JD, UK (corresponding author: [email protected]); 2Aristotle University

of Thessaloniki, Civil Engineering Department, 54124, Thessaloniki, Greece (on leave); 3Roma Tre University,

Department of Engineering, Via Vito Volterra 62, 00146 Rome, Italy

KEYWORDS:

New composite materials, systems and strengthening techniques; Experimental study; Bond and interfacial

stresses; Bond and interfacial stresses; Steel-Reinforced Grout (SRG); Digital Image Correlation (DIC)

ABSTRACT:

The use of externally bonded Steel-Reinforced Grout (SRG) composites, comprising Ultra High Tensile Strength

Steel (UHTSS) textiles embedded in an inorganic mortar matrix (Fig. 1), has been shown to provide an effective

and cost-efficient solution for the repair and strengthening of existing structures. Although several studies have

been carried out in the last decade to investigate the SRG-to-concrete bond behaviour, most of the existing

literature examines the use of systems with a single layer of steel textile and only limited information is available

on multi-ply SRG composites, which are often required for applications to large structural elements. This paper

presents the preliminary results of an experimental study on SRG systems comprising multiple layers of galvanized

UHTSS textiles within a geopolymer mortar. The investigation comprises three stages: 1) direct tensile tests on

SRG coupons to characterize the tensile properties of the composite system; 2) lap-splice tests (for overlap length

ranging from 100 mm to 300 mm) to develop an improved understanding of the textile-to-textile load transfer

capacity; 3) single-lap bond tests to examine the effect on bond behaviour of number of steel textile plies (one,

two or three) and steel cord density (4 and 8 cords/in) on concrete substrates. Digital Image Correlation (DIC) was

used to obtain full-field displacement measurements and map crack development.

Figure 1 (a) Schematic of a single cord embedded in grout(b) of density 4 cord/in (left), 8 cords/in (right)

(a) (b)




DURABILITY OF TEXTILE REINFORCED MORTAR (TRM) SYSTEMS

Francesca Giulia Carozzi1, Pierluigi Colombi1, Tommaso D’Antino1, Carlo Poggi1

1 Politecnico di Milano, Department of architecture, Built Environment and Construction Engineering, Milan,

Italy; (corresponding author: [email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; Durability, long-term

performance; FRC and cement composite materials; TRM systems

ABSTRACT:

Textile Reinforced Mortar (TRM) materials are an innovative strengthening technique particularly used in the

retrofitting of masonry structures. These systems are composed of a fibers grid embedded in an inorganic matrix

(lime or cementitious mortar) sometimes enriched with short fibers.

The knowledge of the durability of these composite materials is of primary importance in order to calibrate design

guidelines and to evaluate the design life of the strengthened structure. In literature only few experimental works

are available, and only a limited number of systems and aggressive environments are considered.

In this work a large experimental campaign is described. A series of TRM (also pre-cracked) and dry textile

specimens were subjected to freeze and thaw cycles, alkaline environment and saltwater. After the conditioning,

the samples were subjected to tensile tests and the results were compared with the ones obtained by tests performed

on control specimens. In particular the slops of the different phases of the stress-strain curves, and the stress

reached at the first cracking phase and at collapse are compared. Different materials were analysed, composed of

lime or cementitious mortars and Glass, PBO, Basalt and Carbon fibers. A total number of about 150 tests was

performed.

The experimental results obtained and the analysis reported could represent an important contribution in the

calibration of a guidelines procedure.

Figure 1: Tensile test on FRCM sample




STUDY OF THE MATRIX-FIBER BOND BEHAVIOR OF CARBON AND GLASS

FRCM COMPOSITES

Lesley H. Sneed1, Tommaso D’Antino2, J.H. Gonzalez-Libreros3, Christian Carloni4, Carlo Pellegrino3

1 Missouri University of Science and Technology, Department of Civil, Architectural and Environmental

Engineering, Rolla, MO, USA; 2 Politecnico di Milano, Department of Architecture, Built Environment, and

Construction Engineering, Milan, Italy; 3 University of Padua, Department of Civil, Environmental, and

Architectural Engineering, Padova, Italy 4 University of Bologna, Department of Civil, Chemical,

Environmental, and Materials Engineering, Bologna, Italy; (corresponding author: [email protected])

KEYWORDS:

New composite materials, systems and strengthening techniques; Experimental study; Characterization of FRP

and FRC materials/systems; Bond and interfacial stresses; FRCM; Effective bond length.

ABSTRACT:

Strengthening and retrofitting of existing reinforced concrete (RC) elements have been gaining interest in recent

decades. Among the strengthening solutions available, fiber reinforced composites present certain advantages,

such as high strength-to-weight ratio and low invasivity, which make them attractive in some applications. In

particular, fiber reinforced polymer (FRP) composites have been successfully employed for bending and shear

strengthening and for confinement of axially loaded elements, however they suffer from UV degradation,

(relatively) high temperature exposure, and cannot be applied onto wet surfaces. To overcome these limitations,

which are mostly related to the use of organic binders (usually epoxy resins), a new type of composite comprised

of a fiber mesh embedded within an inorganic matrix has recently been developed and is referred to as fiber

reinforced cementitious matrix (FRCM) composites. While FRCM composites have proven effective for

strengthening RC elements, each specific composite presents a different behavior and needs to be properly

characterized. In this paper, the results of single-lap direct-shear tests of carbon and glass FRCM-concrete joints

are presented and discussed. Specimens with different composite bonded lengths were tested in an attempt to

identify the effective bond length of each composite. The debonding stress experimentally obtained for carbon

FRCM composites is also compared with that obtained through a fracture mechanics approach based on fiber

strains measured on the same material using strain gauges bonded to the longitudinal fibers.




NUMERICAL ANALYSIS OF PBO FRCM-CONCRETE JOINTS

Tommaso D’Antino1, Lesley H. Sneed2, Christian Carloni3, Carlo Pellegrino4

1 Politecnico di Milano, Department of Architecture, Built Environment, and Construction Engineering, Milan,

Italy; 2 Missouri University of Science and Technology, Department of Civil, Architectural and Environmental

Engineering, Rolla, MO, USA; 3 University of Bologna, Department of Civil, Chemical, Environmental, and

Materials Engineering, Bologna, Italy; 4 University of Padova, Department of Civil, Environmental, and

Structural Engineering, Padova, Italy (corresponding author: [email protected])

KEYWORDS:

New composite materials, systems and strengthening techniques; Material; Bond and interfacial stresses; FRC

and cement composite materials; FRCM; Numerical analysis.

ABSTRACT:

The use of fiber reinforced composites for strengthening and retrofitting existing reinforced concrete (RC)

structures has been increasing popularity in the last few decades. Fiber reinforced polymer (FRP) composites have

been heavily studied and proven successful for bending and shear strengthening of RC beams and slabs and for

confining axially loaded RC elements. Recently, fiber reinforced cementitious matrix (FRCM) composites, which

are comprised of high-strength fiber net embedded within inorganic matrices, have been proposed as an alternative

to FRP composites.

The bond behavior of fiber reinforced cementitious matrix (FRCM) composites applied to concrete elements is

investigated in this paper by means of a three-dimensional numerical analysis. The FRCM-concrete joints studied

are part of an extensive experimental campaign conducted using the single-lap direct-shear test set-up and include

specimens both with and without the external layer of matrix. The input data of the numerical models are obtained

applying a fracture mechanics approach that allowed for studying the shear stress – slip relationships that

characterize the matrix-fiber interfaces. The load responses and strain profiles obtained from the numerical models

of specimens with and without the external matrix layer are compared with the corresponding load responses and

strain profiles observed in the experimental tests. A good agreement between the numerical solutions and the

experimental results is obtained.

Figure 1: Single-lap direct-shear test.




BOND BEHAVIOR OF BASALT TEXTILE GRID IN UHDCC

Jiafei Jiang 1,2, Xiangxiang Dou 1, Jiangtao Yu 1, Haibei Xiong 1

1 College of Civil Engineering, Tongji University, Shanghai, China; 2 College of Civil Engineering, Tongji

University, Shanghai, China (corresponding author: [email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; FRC and cement composite

materials; Bond and interfacial stresses

ABSTRACT:

Textile reinforced mortar (TRM) is one possible solution to replace the organic binding for the application of fiber

reinforced polymer (FRP) in retrofitting. Although it can solve the fire resistance and durability issue from epoxy,

but the brittle fracture of the traditional mortar makes great influences on the bond strength transfer between matrix

and fiber and subsequently causes a significant decrease on the efficiency of fibers/textiles. A new inorganic

composite, textile reinforced ultra high ductility cementitious composite (TR-UHDCC), was proposed to replace

the mortar and expected to have an attractive foreground of engineering applications for UHDCC and large rupture

strain (LRS) FRP. Fundamentally, the transfer of force from the textile to UHDCC is accomplished through the

bond properties which finally affect the tensile behaviour of TR-UHDCC. In this paper, the experimental study is

presented, targeting on the basalt textile grid reinforced UHTDCC. The UHDCC was developed by Yu et al (2017),

which is PE fiber reinforced cementitious composite and has higher rupture strain before strain-softening than

traditional Engineered Cementitious Composite (ECC). The double-sided pull-out test was conducted on 54

specimens. The bond performance is studied with consideration of the bridging effect from the fibers in the matrix.

The bond behavior differs with different failure modes, which is related to the embedded length, grid spacing and

warp and weft spacing ratio.

a) Dimension of specimens b) Test set-up

Figure 1 : Pull-out test of basalt textile grid embedded in UHDCC




A MULTISCALE APPROACH FOR TEXTILE REINFORCED CONCRETE:

ILLUSTRATION ON TRC SANDWICH PANELS

Zakaria.Ilyes .Djamai1, Ferdinando .Salvatore1, Amir.Si Larbi1, Mohamed.El Mankibi2

1- Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne (ENISE), Laboratoire de Tribologie et de

Dynamique des Systèmes (LTDS), UMR 5513, 58 rue Jean Parot, 42023 Saint-Etienne Cedex 2, France.

2- Département de Génie Civil et Bâtiment, Ecole Nationale des Travaux Publics de l’Etat (ENTPE), 3 Rue

Maurice Audin, 69518 Vaulx-en-Velin, France

Corresponding author : [email protected]

KEYWORDS:

textile-reinforced concrete, multiscale, finite element modelling, bond slip law, pull-out failure, anchorage length,

sandwich panels.

ABSTRACT

The present study establishes a numerical strategy for describing the textile /concrete bond behaviour in textile-

reinforced concrete (TRC) composites that separates the cohesive and coulomb friction contributions.

The textile -concrete bond approach, validated on an existing pull out test in the literature, has been used to

calibrate the textile-concrete bond slip law of an existing TRC tested in tension by an innovative inverse approach

thanks to its pull-out mode of failure.

The calibrated bond slip law has been used as an input parameter to produce an enhanced TRC multiscale

numerical model that is based on the nonlinear behaviour of its constitutive components (concrete, textile, and

textile-concrete bond slip law) and takes into account all the damage mechanisms of TRC, which are mainly

characterized by matrix cracking and yarn pull-out .The model has been validated on the basis of the previous

TRC experimental tensile test.

3D TRC multiscale finite element approach which involves definition of the textile-concrete interaction bond slip

law has been used to evaluate the behavior of a TRC sandwich panel. Accurate results have been achieved with

the TRC multiscale approach; furthermore, the experimental mode of failure of the sandwich panel has been

captured




INFLUENCE OF PRE-IMPREGNATION PROCESS ON MECHANICAL

PERFORMANCE OF GLASS/ETTRINGITIC MATRIX COMPOSITE

Omayma HOMORO, Marie MICHEL, Emma LANOYE, Thouraya N. BARANGER

Université de Lyon, Université Lyon 1, Laboratory of Composite Materials for Construction (LMC2), 82 bd

Niels Bohr, F-69622 Villeurbanne, France. Mail: [email protected], [email protected],

[email protected], [email protected]

KEYWORDS:

Strengthening and repair, Experimental study, glass multifilament yarns, ettringitic matrix, pre-impregnation

ABSTRACT:

FRP used in many applications for new light structures and for the strengthening or repair of old structural

elements, TRC (Textile reinforced concrete) has also mechanical properties and durability, which are appropriate

to these purposes. However, the use of multifilament reinforcements for cements is challenging because the cement

particles can not fully penetrate the space between the inner filaments, so we obtain a yarn in which the external

filaments are in direct contact with the matrix, but the internal filaments are relatively free (Figure ), which

decreases the yarn/matrix bond and consequently the mechanical performance of the composite.

The objective of this study is to improve this bond by pre-impregnating the glass yarn with mineral

powder according to two different processes: Conventional pre-impregnation in a wet way and pre-impregnation

in a dry way which is based on the use of an alternating electrostatic field that allows to impregnate powder into

yarns. This innovative process developed by Fibroline1 provides an homogeneous distribution of powder and

increase the degree of impregnation. Classical pull-out tests have been used for the mechanical characterization

of an AR glass yarn embedded in an ettringitic matrix. Three types of specimens have been tested: a dry yarn, a

yarn pre-impregnated in a wet way with matrix particles, and a yarn per-impregnated in a dry way with different

types of powder. These tests allowed to identify the mechanical properties of the yarn/matrix interaction and to

highlight the efficient pre-impregnation process.

In order to better understand the filaments/matrix interaction mechanisms and explain the pull out

behavior, this study has been completed by microscopic observations using the X-ray tomography and by carrying

out direct tensile tests on composites consisting of matrix and yarn, which are treated in the same way as the pull

out tests.

Figure 1: pull-out specimen: glass yarn embedded in ettringitic matrix

Matrix

Metal rods

Yarn

Filaments

Matrix

External filaments

Internal filaments


mailto:[email protected],%[email protected]

mailto:[email protected],%[email protected]





APPLICATION OF A TRILINEAR BOND-SLIP MODEL TO FRCM-CONCRETE

JOINTS

Xingxing Zou1, Lesley Sneed 1, Tommaso D’Antino 2, Christian Carloni 3

1 Missouri University of Science and Technology, Department of Civil, Architectural and Environmental

Engineering, Rolla, MO 65409, USA; 2 Politecnico di Milano, Department of Architecture, Built Environment,

and Construction Engineering, Milan, Italy; 3 University of Bologna, Department of Civil, Chemical,

Environmental, and Materials Engineering, Bologna, Italy


KEYWORDS :

Fiber reinforced cementitious matrix (FRCM) composite; Trilinear bond-slip model; Effective bond length; New

composite materials, systems and strengthening techniques.

ABSTRACT:

This study presents an analytical approach for predicting the load-slip response of fiber reinforced cementitious

matrix (FRCM)-concrete joints. The FRCM-concrete interfacial behavior was described with a trilinear cohesive

material law consisting of a linear stage, a softening stage, and a friction stage. Accordingly, provided that the

bonded length is longer than the composite effective bond length, the full-range applied load-global slip response

consists of five stages: an elastic stage, an elastic-softening stage, an elastic-softening-debonding stage, a

softening-debonding stage, and finally a fully debonded stage. Closed-form solutions for the applied load-global

slip, interfacial shear stress distribution, and longitudinal stress distribution along the composite bonded length

were derived. Also, the debonding load, peak load, and the effective bond length were analytically obtained.

Results of the analytical model were compared to experimental results of six single-lap shear specimens

instrumented with strain gauges mounted to the longitudinal fibers along the composite bonded length.




SINGLE FIBRE-TO-MORTAR BOND CHARACTERIZATION IN TRM

COMPOSITES

Bahman Ghiassi1, Ali Dalalbashi2, Daniel V. Oliveira2

1 Department of Civil Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United

Kingdom, ([email protected])

2 ISISE, University of Minho, Department of Civil Engineering, Guimarães, Portugal

KEYWORDS

Strengthening and repair; Experimental study; Bond and interfacial stresses; FRC and cement composite

materials; TRM; Pull-out test.

ABSTRACT

Textile-reinforced mortars (TRM) have been identified as sustainable materials for externally bonded

reinforcement (EBR) of masonry and historical structures. The fibre-to-mortar bond, the TRM-to-masonry bond,

and the mechanical properties of the TRM constituents have a fundamental role in the performance of this

strengthening technique. Although several studies can be found in the literature with the focus on characterization

of the tensile response and TRM-to-masonry bond behaviour, the fibre-to-mortar bond response that plays a

critical role in the performance of these systems have received few attention.

This paper, as an step towards addressing the gap in characterization of the fibre-to-mortar bond behaviour,

presents an experimental and analytical investigation on the effect of test setup and fiber embedded length on the

pull-out response and bond-slip laws in TRM composites. Three different pull-out test setups, consisting of one

pull-pull and two pull-push configurations, are developed and investigated for characterization of the single fibre-

to-mortar bond behaviour. The experimental and analytical results are discussed and presented and bond-slip laws

are extracted for each test setup and embedded length.





Bond




MODE II INTERFACE CONSTITUTIVE LAW FOR CONCRETE SUBSTRATES

STRENGTHENED WITH STEEL REINFORCE POLYMERS

Francesco Ascione1, Marco Lamberti 1, Annalisa Napoli 1, Ghani Razaqpur 2 , Roberto Realfonzo1

1 University of Salerno, Department of Civil Engineering, Salerno, Italy; 2 Nankai University, Department of

Environmental Science and Engineering, Tainjin, China; 3


KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; Bond and interfacial

stresses; Seismic applications

ABSTRACT :

A new effective and economical solution was recently introduced for the external strengthening of RC existing

structures, which consists of an innovative composite material using steel wires in lieu of traditional carbon and

glass continuous fibers, embedded in a polymer matrix. The steel fabric can be externally bonded to a substrate

via wet lay-up, using either epoxy or polyester resin. The resulting composite system is termed Steel Reinforced

Polymer (SRP).

In order to properly predict the debonding load and the interface mode of failure, robust local bond-slip model is

required. When estimating debonding failure load, many design guidelines consider the mode II fracture energy

as the key material property. For SRP-concrete interfaces the above quantity has not been yet established.

Consequently, two nonlinear interface laws are here presented and calibrated using several results of a previous

large experimental program on SRP-to-concrete bonded joints in terms of axial strain measurements of the steel

strips. The first bilinear interface law presented, was originally proposed for FRP-to-concrete system. The second

nonlinear bond-slip law is proposed by the authors. The calibration procedure consists of least square minimization

between theoretical and experimental data. The results obtained show that, for the case of the SRP system, the

proposed local bond-slip model provides a more accurate prediction of the maximum shear stress and

corresponding slip than the counterpart bilinear law.




FRP-TO-CONCRETE DEBONDING - GLOBAL AND LOCAL BOND BEHAVIOUR

M. Breveglieri 1*, A. Hosseini 1,2 and C. Czaderski 1

1 Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf

Resilient Steel Structures Laboratory, EPFL, Lausanne, Switzerland

*Email: [email protected]

KEYWORDS :

Strengthening and repair; Modeling ; Bond and interfacial stresses; Codes, standards and design guidelines; FRP-

Concrete interfacial shear stress

ABSTRACT:

FRP (fiber reinforced polymer) strips are used to flexurally strengthen reinforced concrete (RC) beams. The global

bond strength namely the maximum transferable bond stress due to the increase of FRP tensile stress in a cracked

concrete element (subsequently named as global bond shear stress) is a relevant aspect of flexural strengthening

design. The differences between the bond strength in an uncracked concrete (end anchorage) and in a cracked

concrete element have been highlighted in the existing literature; however, despite a large number of research

works on the simple lap-shear test (local bond shear stress), less effort has been dedicated to investigate and model

debonding on a global view. The current version of Swiss code on externally bonded reinforcement (SIA 166-

2004) limits the local and global bond strength by means of the shear stresses, τf,max=τl0 and τl,lim, which are both

assumed to be only functions of the concrete tensile strength. Nevertheless, it has been demonstrated in the

literature that the maximum interfacial shear stress between two adjacent flexural (or flexural-shear) cracks

depends also on the stress level in the FRP (σo). In the current paper, the difference between the local and global

bond behavior and its debonding processes is explained and discussed with analytical and numerical models.

In analogy to the existing approach developed to study the bond behavior of prestressed carbon fiber reinforced

polymer (CFRP) strips during force release, a fracture energy-based model is proposed in the current study to

determine the maximum global bond developed in a so-called intermediate crack element (ICE). The proposed

model is a function of the FRP tensile stress (σo) and assumes a constant shear stress law. It is here demonstrated

that the proposed model provides similar results to the more complicated models available in the literature. The

main findings are here discussed with the aim to evaluate the feasibility of this new model for a future enhancement

of the Swiss code.





BOND BEHAVIOR OF PRE-CURED CFRP STRIPS TO CONCRETE USING

EXTERNALLY BONDED REINFORCEMENT ON GROOVE (EBROG) METHOD

Niloufar Moshiri 1,2, Davood Mostofinejad 1, Amir Tajmir-Riahi 1

1 Isfahan University of Technology (IUT), Civil Engineering Department, Isfahan, Iran

2 Swiss Federal Laboratories for Materials Science and Technology (Empa)

(Corresponding author: [email protected])

KEYWORDS

Strengthening and repair, Experimental study, Bond and interfacial stresses, EBROG method, CFRP strips, DIC,

Externally Bonded Reinforcement On Groove.

ABSTRACT

FRP debonding from concrete substrate may lead to premature failure and diminish the FRP-strengthening

performance. Externally Bonded Reinforcement On Groove (EBROG) technique has been presented as a

promising substitute to Externally Bonded Reinforcement (EBR) in order to postpone FRP debonding.

Eliminating/postponing of debonding of FRP sheets installed through wet layup EBROG was demonstrated in

previous studies. In this research, bond behavior of pre-cured CFRP strips with much higher level of stiffness and

strength were investigated to examine versatile efficiency of EBROG technique. To do so, 6 specimens were

strengthened with EBR and EBROG techniques. Bond resistance and failure modes were experimentally assessed.

EBROG method removed the concrete failure and thus, helped the bonded joint to resist higher anchorage

resistance. Specimens with two longitudinal grooves in this study experienced a bond resistance twice of those in

EBR specimen. In addition, inspecting slip distribution revealed that effective bond length was longer in EBROG

method compared to EBR.




BOND RESISTANCE OF A SINGLE GROOVE IN EBROG METHOD TO ATTACH

CFRP SHEETS ON CONCRETE

Amir Tajmir-Riahi 1, Davood Mostofinejad 1, Niloufar Moshiri 1,2

1 Isfahan University of Technology (IUT), Civil Engineering Department, Isfahan, Iran

2 Swiss Federal Laboratories for Materials Science and Technology (Empa)


KEYWORDS

Strengthening and repair; Experimental study; Bond and interfacial stresses; EBROG method; Size effect, FRP

sheet.

ABSTRACT

Nowadays the strengthening of existing building in order to ensure proper operation in emergency time is one of

the most important construction industry’s challenges. Because of composite sheets fast and easy implementation,

their very low weight and very high tensile resistance and ability to resist corrosion, FRP composite sheets has

become one of the most widespread materials for strengthening of concrete structures. The conventional method

for utilizing FRP sheets is externally bonded reinforcement (EBR). The main advantage of EBR technique is facile

installation, but premature debonding of FRP sheets has restricted EBR technique. Externally bonded

reinforcement on groove (EBROG) method has been proposed as an alternative to EBR method. EBROG in

comparison with EBR is capable of postponing/eliminating of debonding phenomenon and the results have been

discussed in the literature. In this paper, load carrying capacity of a single groove is experimentally evaluated. To

focus on bond resistance of a groove, just one groove with length of 200mm is created in the middle of bond zone.

Size effect of grooves is another intention of the current research. To do so, single shear tests were conducted on

8 specimens with dimension of 150×150×350mm that were strengthened with EBR and EBROG. Results showed

that the maximum load carried by an EBROG joint is much more than that of the counterpart EBR joint. The bond

resistances of a single groove in EBROG joint are also compared in different sizes of grooves. In addition, an

innovative method was proposed to evaluate the effective bond length.





WIDTH EFFECT OF INTERFACIAL BOND

Yu-Fei Wu 1, Jian-Ping Lin 2, Liang He 3

1 Professor, School of Engineering, RMIT University, Australia

(corresponding author: [email protected]);

2 Lecturer, College of Civil Engineering, Huaqiao University, Xiamen, China;

3 Engineer, Guangzhou Metro Design and Research Institute Corporation Limited, China.

KEYWORDS

Interface, bond, size effect, width effect, fracture mode.

ABSTRACT

The bond properties of an interface in composite structures are generally considered as local mechanical

characteristics in extant literature. Through experimental testing, analytical study, and numerical simulation, it is

shown in this work that the interfacial bond characteristics are generally size dependent and non-local structural

properties. Interfacial shear bond generally involves both Mode II and Mode III fractures. When both fracture

modes are involved, the bond characteristics are size dependent. However, when only Mode II fracture is involved,

the interfacial bond is size independent. Rational study of the problem indicates that some key and important

factors have not been considered in existing models. A more sensible and accurate bond model considering all the

key factors and the size effect is developed in this work for externally bonded FRP-to-concrete joints.





THE BOND BEHAVIOR OF SRP-TO-CONCRETE SYSTEM IN FIELD

ENVIRONMENT

Wei Wang 1, and John J. Myers 2

1 PhD Candidate, Department of Civil, Architectural &Environmental Engineering, Missouri University of

Science and Technology, MO, USA

2 Professor, Department of Civil, Architectural &Environmental Engineering, and Associate Dean, Missouri

University of Science and Technology, MO, USA

KEYWORDS:

Steel reinforced polymer (SRP), micro-fine galvanized and micro-fine brass coating steel fibers, freeze-thaw,

temperature and moisture conditions, flexural bending tests, direct pull-off bond tests.

ABSTRACT:

In this study concrete beams reinforced with a steel reinforced polymer (SRP) strengthening system that were

loaded and unloaded were subjected to real-time seasonal weather and solar exposure in Rolla, MO for 12 months.

Two types of steel fibers (micro-fine galvanized and micro-fine brass coating steel fibers) were used in this study.

A total of 22 SRP specimens, including 12 specimens loaded and 10 specimens unloaded, were maintained in

outdoor weather in Rolla, which has moderate UV radiation with various freeze-thaw, and variable temperature

and moisture conditions. Flexural bending tests and direct pull-off bond tests were performed to evaluate the long-

term bond performance of SRP-to-concrete interfaces. The flexural bending test results illustrated that the bond

behavior between SRP and concrete was affected by the harsh environmental conditioning. The results for the

pull-off test were scattered. This high variability was related to several issues such as non-homogenous

characteristic of the concrete, applied load rate using hand, or the inappropriateness to prepare the specimens.

INTRODUCTION:

Currently, there are several composite application technologies to repair and retrofit deficient and aging concrete

members in existing buildings and bridges. These technologies involve manual FRP lay-up, pre-cured laminate

plates, near surface mounted (NSM) bars, mechanically fastened FRP, and SRP. There is limited available data to

exhibit the influence of real-time seasonal weather on the bond performance between SRP strengthening systems

and concrete. Deng et al. (2015) evaluated durability performance of concrete beams reinforced with CFRP sheet

under real-time weather and solar exposure, and found flexural strengths showed a 45% loss. The failure modes

were also changed from substrate to interfacial. Direct pull-off tension strength decreased after 18 months of real-

time exposure. Liau and Tsent (1998) reported that that cracks occurred when CFRP specimens were exposed to

the UV, finally reducing the strength due to stress concentrations.

In order to investigate the effects of field exposure on the bond performance of concrete beams reinforced with

SRP, they were subjected to real-time weather and solar exposure in Rolla, MO for 12 months (from October 2015

to September 2016). A total of 22 SRP specimens, including 12 specimens loaded and 10 specimens unloaded,

were maintained in outdoor weather in Rolla, which has moderate UV radiation with various freeze-thaw, and

variable temperature, and moisture conditions. These SRP specimens were tested in three-point loading. At the

same time, direct pull-off tension tests were conducted after 12 months of exposure.

EXPERIMENTAL PROGRAM:

In this study, Hardwire® tapes of 5 wires per inch were utilized with 3x2-G Hardwire® (a new galvanized coated

wire version-RG) and 3x2 Hardwire® (RNG) were applied individually to specimens to study the durability

performance of concrete members reinforced externally with composite materials made from Hardwire® and

epoxy (SRP). In addition, Sikadur® 330, which consists of Sikadur® 330 US Part A (component A) and Part B

(component B), was used. Plain concrete beams with a compressive strength of 6010 psi (41.4 MPa) were cast.




The dimension of the specimens were 6 in. (width) x 6 in. (height) x 24 in. (length) (152.4 x 152.4 x 609.6 mm)

based on ACI 440.9R-15 provisions. The bond durability between the SRP strengthening system and concrete

substrate was evaluated through a flexural three-point bending test (ASTM D790-17) and a direct pull-off test

(ASTM D30-09).

RESULTS AND DISCUSSION:

Flexural Bending Test (FBT)

No sign of corrosion was observed on the surface of the SRP strengthening system for the exposed specimens. It

can be concluded that the epoxy resin utilized in this research exhibited a perfect moisture-tolerant behavior to

protect the steel fibers for the period studied. The average percentage of concrete cover area for the control

specimens was 31.5%. In contrast to this, the percentages of concrete cover area of loaded (40% and 20%) and

unloaded specimens decreased by 60.6%, 24.8%, and 34.3% respectively.

Pull-off Test (POT)

There was a large degree of scatter and variation in the test results, indicating the variability of this test method.

The average bond strength of control RG specimens was almost the same as the results of the control RNG

specimens. While this test method may be suitable for minimum bond compliance verification during

strengthening installation, it seems inappropriate to capture degradation in the system. As indicated in Figure 1 (c

and d), it may be noted that the failure occurred in the concrete substrate indicating that the failure did not occur

in the interface between the strengthening system and concrete substrate.

(a) FBT control (b) FBT conditioned (c) POT control (d) POT conditioned

Figure 1. Representative failed specimens from control and conditioned FBT and POT tests

CONCLUSIONS:

Test results of three-point loading tests indicated that the externally bonded SRP strengthening systems can capture

the durability performance and degradation factors, CE, can be established for use in design models such as ACI

440.2R. When subjected to real-time weather and solar exposure, the concrete covered areas of the exposed

specimens reduced significantly when compared to the counterparts of the control specimens. The degradation

should be attributed to loss of adhesion at the bond surface due to the influence of moisture and temperature.

For direct pull-off tests, this study determined a 5.3% (RG specimens) and 13.8% (RNG specimens) tensile

strength increase when the specimens were exposed to real-time weather and solar exposure for 12 months. The

results of this test exhibited a large degree of scatter and variation, indicating the variability of this test method.

Therefore, direct pull-off tests may not be considered as a technology to evaluate the long-term bond performance

of SRP-to-concrete systems. However, it may be an effective avenue for installation minimum bond compliance.




FLEXURAL STRENGTHENING OF RC BEAMS USING SIDE NSM CFRP BARS:

AN EXPERIMENTAL INVESTIGATION

Thanongsak Imjai 1, Udomvit Chaisakulkiet 2 and Reyes Garcia 3

1 Dept. of Civil Engineering, Rajamangala University of Technology Tawan-Ok, Bangkok, Thailand;

(Email: [email protected])

2 Dept. of Civil Engineering, Rajamangala University of Technology Rattanakosin, Bangkok, Thailand;

3 Dept. of Civil Engineering, The University of Sheffield, Sheffield, UK;

KEYWORDS :

Strengthening and repair; Structure ; Bond and interfacial stresses; Side Near-surface Mounted; SNSM

ABSTRACT:

The strengthening of existing reinforced concrete (RC) elements is a leading challenge in civil engineering. The

need strengthening of RC structures can be due to an increase in design loads, construction errors in design or

workmanship, changes in design guidelines and/or live loads, or a combination of the above. A promising

strengthening technique for RC components is the use of near-surface mounted (NSM) FRP reinforcing bars or

strips into pre-cut grooves in the member. Normally, NSM FRP reinforcement is placed into pre-cut grooves at

the bottom/soffit of concrete elements. Such practice is difficult to implement in many countries (especially in

Thailand) because mechanical and electrical wiring is usually placed in pipes placed and cast near the soffits of

slabs and beams. As a result, alternative ways of installing NSM FRP reinforcement in existing structures are

necessary.

This paper presents initial results from tests aimed to examine the use of side near-surface mounted (SNSM) FRP

bars or strips to strengthen RC members. To achieve this, four-point bending tests were carried out on five

150x250x2500 mm RC beams using different SNSM FRP strengthening configurations. Typical construction

practices used in Thailand for strengthening of structures were adopted. The results are discussed in terms of

cracking, observed failure modes, load-deflection behaviour, and effectiveness of the strengthening solution. The

results indicate that the SNSM technique offers significant enhancement in flexural performance of RC beams in

both tension and compression, although the effectiveness is somehow limited by debonding of the FRP bars.

Figure 1 : Application of side near-surface mounted FRP reinforcing bar on RC beams

Placing of CFRP rod into the side groove Application of epoxy resin along the groove




ANALYSES ON THE BOND TRANSFER BETWEEN FRP COMPOSITES AND

OTHER STRUCTURAL MATERIALS

Hugo Biscaia1, Carlos Chastre2, João Cardoso3, Noel Franco4

1 Fluid and Structures Engineering, UNIDEMI, Department of Civil Engineering,

NOVA University of Lisbon, Portugal. Email: [email protected]

2 Civil Engineering Research and Innovation for Sustainability, ICIST, Department of Civil Engineering,


3 Fluid and Structures Engineering, UNIDEMI, Department of Mechanical and Industrial Engineering,


3 Department of Civil Engineering,


KEYWORDS:

FRP composites; Concrete; Timber; Steel; Masonry; Aluminium; Bond; Modelling.

ABSTRACT:

Fibre Reinforced Polymer (FRP) can be used as a strengthening material in several types of structures built with

different materials, such as concrete, timber, steel, aluminium or clay masonry. Contrary to fasteners, the bond

technique currently used to connect the FRP composites to the substrate avoids stress concentrations. The

knowledge on the performance of those bonded joints has been increasing but there are several issues not well

understood yet. For instance, it is not clear which interfacial local bond-slip relationship should represent best each

type of interface. Such knowledge could be important for distinguishing different bond behaviours that, along with

the contribution on to the field of the numerical and/or analytical modelling, will certainly help to identify the main

causes for such differences between them all. Furthermore, the case of bonded joints between FRP and masonry

clay bricks is now starting their first steps and in this particular case, the actual knowledge needs to be improved

in order to increase the heritage building life cycle. Likely to other bonded joints such as FRP/concrete,

FRP/masonry joints have been tested under single/double-lap shear conditions as well. These two bonded joints

share, at least, one common particularity: both develop cracks when submitted to tensile stresses. Therefore, it is

expected that similar interfacial bond-slip relationships may be used in both circumstances. In bonded joints

between FRP composites and steel or timber substrates, the cracking phenomenon doesn't arise. However, on

FRP/timber interfaces, depending on the type of the timber used or depending on the orientation of the grains

throughout the bonded area, the interfacial bond-slip relationship may change. The work herein reported presents

a full comparison of bonded joints between FRP composites and other structural materials in which will be used

different analytical approaches to model their debonding behaviours. All modelling is based on cohesive bond-

slip relationships experimentally obtained from tests carried out by the authors or collected from the literature

which have the purpose of locally induce a cohesive rupture within the adhesive.




COHESIVE ZONE MODELLING OF A PRESTRESSED NON-MECHANICAL CFRP

ANCHORAGE SUBJECTED TO FREEZE-THAW CYCLES

Yunus Emre Harmanci1,2, Edmunds Zile3, Julien Michels 4, Eleni Chatzi 1

1 Department of Structural Engineering, ETH Zurich, Zurich, Switzerland; 2 Structural Engineering Research

Lab., Empa, Dübendorf, Switzerland; 3 Institute for Mechanics of Materials, University of Latvia, Riga, Latvia;

4 re-fer AG, Brunnen, Switzerland

KEYWORDS:

Strengthening and repair; Modeling ; Bond and interfacial stresses; Prestressing with FRP composites;

Durability, long-term performance

ABSTRACT:

The application of prestressed carbon fiber reinforced polymers (CFRP) as an externally bonded reinforcement

has attracted significant attention due to its well-known advantages both for the ultimate state as well as

serviceability conditions. Initially conceptualized by Urs Meier1, gradient anchorage offers an alternative to

conventional mechanical anchoring techniques purely based on the bond between CFRP-epoxy-concrete. It is

achieved by a segment-wise prestressing force release at the strip end after the accelerated curing of epoxy under

high temperatures. The long-term behaviour is a significant factor for real-world applications due to the thermal-

and moisture sensitive nature of epoxy. Experimentally, it has been observed that FTC causes a reduction in the

residual anchorage resistance and deformation capacity of the system. Moreover, the failure mode is switched

from a concrete substrate to an epoxy-concrete interface failure. In order to accurately capture the failure

mechanisms, a cohesive zone modelling (CZM) approach is herein. Zero-thickness cohesive elements are

embedded between each continuum element, and subsequently constitutive traction-separation laws of the concrete

substrate and epoxy-concrete interface are introduced. These laws are derived via an inverse analysis relying on

experimental observations, obtained via digital image correlation. The CZM approach proves successful in

accurately simulating the experimentally observed behaviour based on the provided traction-separation curves.

1Meier, U., and Stöcklin, I. (2005). “A Novel Carbon Fiber Reinforced Polymer (CFRP) System for Post-Strengthening.”Int. Conf. on Concrete

Repair, Rehabilitation and Retrofitting (ICCRRR), CRC Press, Taylor &Francis, Boca Raton, FL.




ATOMISTIC INVESTIGATION ON INTERFACIAL DETERIORATION OF EPOXY-

BONDED INTERFACE UNDER HYGROTHERMAL ENVIRONMENT

Chao Wu, Ruidong Wu, Lik-ho Tam *

School of Transportation Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191,

China, Email: [email protected]

KEYWORDS

Epoxy-bonded interface, interfacial integrity, hygrothermal environment, molecular dynamics simulation.

ABSTRACT

The fiber reinforced polymer (FRP) has been increasingly used for strengthening concrete infrastructure through

external bonding by using epoxy adhesive. The long-term durability of FRP-concrete structure is seriously

degraded under hygrothermal environment at high level of temperature and humidity, which is mainly caused by

interfacial debonding between concrete and epoxy. The microscopic information on local interfacial deterioration

is important for understanding the failure mechanism of epoxy-bonded FRP-concrete structure under hygrothermal

environment, which is still lacking at this stage. This paper aims to understand the effect of hygrothermal

environment on nanoscale mechanical and interfacial behavior of epoxy-bonded interface by using molecular

dynamics simulation. The interface model is conditioned in dry and wet environment at room and elevated

temperature. By simulating interfacial debonding process, the structural and mechanical properties of epoxy-

bonded interface are examined, which degrades most seriously in wet environment at elevated temperature,

resulting in significant decrease of interfacial adhesion. The mechanistic knowledge provided in this paper could

contribute to the understanding of environment-affected structural failure of FRP-concrte system from the

nanoscale perspective, and it is believed to be applicable to similar FRP-strengthened structure.




EXPERIMENTAL STUDY OF CFRP-TO-CONCRETE BONDED JOINTS UNDER

FATIGUE LOADING

Hao Zhou, Van Thuan Nguyen, Dilum Fernando

The University of Queensland, St. Lucia, Brisbane, Australia, Email: [email protected]

KEYWORDS

FRP-to-concrete bonded joints, Data acquisition, Fatigue behaviour, Failure mode.

ABSTRACT

Externally bonded (EB) FRP strengthening of reinforced concrete (RC) structures has gained popularity worldwide

because of its many advantages compared to conventional strengthening methods. Performance of the structures

strengthened using EB FRP laminates depends significantly on the performance of the bonded interface between

the FRP and concrete. Therefore, extensive research has been carried out to study the behaviour of FRP-to-concrete

bonded joints, and numerous theoretical models have been developed to predict the behaviour of such bonded

joints under monotonic loading. However, only limited research efforts have been made on understanding and

modelling the behaviour of FRP-to-concrete bonded joints under fatigue cyclic loading. This paper presents the

results of an experimental study aimed at investigating the behaviour of FRP-to-concrete bonded joints under

fatigue cyclic loading. A customized data acquisition system was developed to capture the axial strains of FRP

plate during fatigue cyclic loading. From the test results, it was observed that the loading amplitude, concrete

strength and the type of the CFRP plate used significantly affected the failure mode of FRP-to-concrete bonded

joints under fatigue cyclic loading.




INFLUENCE OF VARIOUS PROCESS PARAMETERS ON THE MECHANICAL

PERFORMANCE OF CFRP/CONCRETE ADHESIVE BOND

Karim Benzarti1, Nicolas Roche2, Corentin Le Roy3, Jeremy Roth3, André Flety3, Christophe Aubagnac3

1 Université Paris-Est, Ecole des Ponts ParisTech, Laboratoire Navier (UMR 8205), France


2 EDF, TEGG/SGC, Organic Materials Group, Aix en Provence, France

3 CEREMA, DTerCE/DLA, Autun, France.

ABSTRACT

CFRP are widely used in RC structures reinforcement and retrofitting, a large majority of which are currently

applied manually by hand lay-up, leading to various defects in the composite laminate and the adhesive bond

depending on the experience of the applicator.

In this experimental study, pultruded CFRP plates were installed on concrete blocks by controlling different

parameters of the bonding process, such as viscosity/consistency of the epoxy adhesive, temperature of the

concrete substrate, application of a contact pressure during bonding operation or the use of vacuum bagging. The

influence of these parameters on various bond characteristics was studied by performing mechanical tests and

micrographic observations. Mechanical bond performances were assessed using an instrumented Single Lap Shear

(SLS) test setup providing the shear capacity of the assembly. Standard Pull-off tests were also performed.

Besides, the morphology/geometry of the concrete/CFRP adhesive joint (thickness of the joint and penetration

depth of the polymer adhesive in the porous concrete substrate) was characterized by optical microscopy, and the

influence of the process parameters on these characteristics was discussed. Finally, the possible relationship

between morphological characteristics of the adhesive joint and mechanical properties was discussed.

KEYWORDS

CFRP, concrete, adhesive bonding, process parameters, pressure, vacuum bagging, bond performances,

morphology of the adhesive joint





Composites structures




LONG-TIME BEHAVIOUR OF GFRP/CONCRETE HYBRID STRUCTURES

Ibrahim Alachek1, Nadège Reboul1, Bruno Jurkiewiez 1

1Université Claude Bernard Lyon1, Laboratoire des matériaux composites pour la construction LMC2, Lyon,

France ([email protected])

KEYWORDS:

Hybrid structures; Creep ; Durability, long-term performance; Bond and interfacial stresses ; Glass fibers

ABSTRACT:

Nowadays, new materials such as high-performance concrete and glass fibre reinforced polymer “GFRP” are

appearing in the construction market. All these materials offer improved performances compared to conventional

materials but they exhibit a brittle behaviour and thus differ from conventional ductile materials. Then to extend

their use, it is necessary to develop material-adapted structure forms and study their behaviours. In this context,

this study presents experimental and numerical investigations about the creep behaviour of a hybrid structure

consisting of I-shaped GFRP pultruded profile bonded to a thin deck made of reinforced concrete. The

experimental program included a flexural creep tests on GFRP I-profiles and on hybrid beams subjected to constant

loads equivalents to one-third of their ultimate loads. To assess the influence of environmental conditions on the

behaviour and the load-carrying capacity of these beams, other beams were left beside the loaded beams during

the test period and they were tested to failure under short term loading at the end of creep tests. The deflections

and axial strains over time, at the midspan sections, were measured in natural environmental conditions and

recorded for time durations up to 3600 h. The test configuration was three-point bending to simulate the most

severe loading in a proposed application. Also in this study, the Finite Element Method has been used for

simulation and stress analysis of hybrid bonded structures under elastic load. A three-dimensional model based on

the linear viscoelastic theory was proposed to study the evolution and distribution of strains and stresses over time.

The parameters of the proposed model were calibrated based on the experimental results. Special adhesive

elements have been used for stress and displacement analyses in adhesively bonded joints. The proposed model

allows predicting the evolution of the strains and displacement over the time period and the stress redistribution.

Figure 1: Creep tests




THE BEHAVIOUR OF DUCTILE LINK SLAB DESIGNED WITH FRP REINFORCED

ECC

Yu Zheng1, Lipeng Xia1, Lifei Zhang1 and Jianbin Yang1

1 Dongguan University of Technology, Department of Civil Engineering, Dongguan China;

KEYWORDS :

Hybrid structures; Experimental study ; FRP internal reinforcement; Durability, long-term performance

ABSTRACT:

In the multispan deck system, mechanical expansion joints are typically designed and employed to facilitate both

rotations and lateral movements between simply supported adjacent bridge spans due to thermal expansions,

shrinkage, creep and girder deflections due to service loads. However, it is well reported that the deterioration of

mechanical expansion joint components, such as rubber aging and steel corrosion, has been one of the major factors

in the deterioration of those bridge structures. A possible approach to solve the durability problem and reduce the

high cost of maintenance in expansion joints is the elimination of mechanical deck joints. As a result, continuous

and jointless bridge decks have been suggested and proposed. One type of jointless bridge design proposed by a

number of researches is the application of link slab elements within bridge deck, which is used to connect the two

adjacent simple-span girders. In this paper, a flexible and corrosion-free link slab element by utilizing highly

ductile ECC and low stiffness non-corrosive FRP reinforcement is proposed and suggested. The proposed link slab

needs to maintain structural integrity and durability while conforming to crack width limitations and having

sufficient deformation capacity. In addition, a low stiffness of the link slab element is desired in order for the two

adjacent simply supported bridge deck spans, connected by the link slab, to undergo unrestrained deformations.

In this study, to verify that the proposed ECC material is able to exhibit the criteria of link slabs in the literatures,

a group of ECC specimens were employed and tested under compression, tension and flexure to investigate the

material properties. Subsequently, a FRP reinforced ECC slab was used as joint link slab in bridge deck structures

and a group of test specimens were conducted, including ECC link slab, ECC link slab reinforced with FRP grid

and ECC link slab reinforced with FRP bars. A series of monotonic repeated loading was applied for all the test

specimens. The performance is described based on the load-deflection/moment-rotation response, strain

development, cracking and energy absorption. The influence of FRP reinforcing materials on the link slab

structural performance is presented and discussed. The significant enhancement of deflection capacity and crack

with control in ECC link slab reinforced with FRP bars suggest that the use of ductile ECC and low stiffness FRP

can effective in extending the service life of joint-free bridge deck system.

9th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2018), PARIS 17-19 JULY 2018


AXIAL COMPRESSIVE BEHAVIOUR OF COMPOSITE TUBES WITH DIFFERENT

GROUT INFILLS

Ali A. Mohammed1,2, Allan C. Manalo1, Ginghis B. Maranan1, Yan Zhuge 1

1University of Southern Queensland, Centre for Future Materials, Faculty of Health, Engineering and Sciences,

Toowoomba, Australia

2The University of Mustansiriya, College of Engineering, Environmental Engineering Department, Baghdad,

Iraq (corresponding author: [email protected] ; ali.mohammed@usq,edu.au)

KEYWORDS:

New composite materials, systems and strengthening techniques; FRP tube; Composite jacket; Characterization of


ABSTRACT:

This paper investigates the effects of grout infill characteristics on the axial compressive behaviour of glass fibre

reinforced polymer (GFRP) tubes to determine the most effective infill for prefabricated composite repair systems.

As detailed in Table 1, five different types of grout infills were considered in this study based on their availability,

with taking into consideration the nominal compressive strength and Modulus of Elasticity (MOE). Grout infills

made from concrete, cementitious and epoxy grouts with compressive strength ranging from 10 MPa to 70 MPa

and MOE ranging from 10 GPa to 35 GPa, respectively, were selected. Characterisation of the compressive

properties of these grouts was conducted. These grouts were then filled into a 3 mm thick GFRP tubes to investigate

the effectiveness of the different grouts in stabilising the composite tubes and effectively utilising its hoop strength.

The experimental results showed that the increase of the grout MOE increases the overall stiffness of the filled

GFRP tube, while a low compressive strength grout (less than 20 MPa) is more effective than high compressive

strength grouts in utilising the GFRP tubes’ hoop strength. Moreover, as depicted in Figure 1, the degree of GFRP

tube rupture decreases and becomes less severe and more localised at the upper section of the specimen as the

grout compressive strength increases, which tends to suggest that increasing the infill compressive strength

decreases the portion of FRP tubes being utilised. Finally, the developed theoretical model predicted accurately

the load-carrying capacities of the GFRP tubes filled with different grouts.

Table 1. Grout infills properties

Type Compressive Strength, MPa MOE, GPa

Cementitious Grout 40.02 34

Epoxy Grout 75.29 12

Concrete (C1) 12.62 19




mailto:ali.mohammed@usq,edu.au



Figure 1. Typical compression failure of FRP tubes with different infills

(a) Hollow tube (b) Filled-C1 (c) Filled-C3




AXIAL COMPRESSION – BENDING INTERACTION OF HYBRID FRP

STRENGTHENED RC COLUMN ELEMENTS

Chellapandian M1, Suriya Prakash S2, Akanshu Sharma3 1 Research Associate, Department of Civil Engineering, Indian Institute of Technology, Hyderabad, India


2 Associate Professor, Department of Civil Engineering, Indian Institute of Technology, Hyderabad, India


3 Junior Professor, Institute of Construction Materials, University of Stuttgart, Germany (Email:

[email protected])

KEYWORDS:

CFRP; EB Strengthening; Interaction Study; NSM Strengthening; Hybrid Strengthening; RC Column Element.

ABSTRACT

Strengthening of reinforced concrete (RC) element is challenging as the efficiency of a particular strengthening

scheme may change under different loading conditions. The importance of hybrid Fiber Reinforced Polymer (FRP)

strengthening on the behavioral improvement of RC column elements under combined axial and bending loads is

investigated. In total, thirty-two RC square elements of dimensions 230 mm (B x D) are cast. The specimens are

tested under different uniaxial eccentric (e) compression like (i) axial compression (e=0), (ii) low eccentric

compression (e=0.15*D), (iii) high eccentric compression (e=0.63*D) and (iv) pure flexure (e=∞). The specimens

are strengthened using (i) Near Surface Mounting (NSM) of Carbon FRP (CFRP) laminates, (ii) External Bonding

(EB) of CFRP fabrics and (iii) Hybrid strengthening which uses a combination of NSM and EB technique. Two

specimens are tested under each series to ensure the consistency of test results. Axial compression (P) – bending

(M) interaction diagram developed from the experimental results revealed that hybrid FRP strengthening resulted

in the best performance under all combinations of axial compression and bending loads. EB strengthening which

exhibited better performance under axial compression had a reduced improvement under combined bending and

compression loads. Moreover, the behavior of NSM strengthened specimens had significant improvement due to

presence of bending in the interaction diagram.







EXPERIMENTAL AND ANALYTICAL STUDY OF GFRP AND UFC COMPOSITE

BEAMS

Isuru Sanjaya Kumara Wijayawardane1, Hiroshi Mutsuyoshi2

1 Saitama University, Department of Civil & Environmental Engineering, Saitama and Japan, Email:

[email protected]

2 Saitama University, Department of Civil & Environmental Engineering, Saitama and Japan

KEYWORDS :

Hybrid structures; Modeling ; FRC and cement composite materials; Characterization of FRP and FRC

materials/systems ; Fiber model analysis ; Flexural behavior

ABSTRACT:

Glass fiber reinforced polymer (GFRP) and ultra-high strength fiber reinforced concrete (UFC) composite beams

are a good alternative for short-span bridge girders located in severe corrosive environments. The outstanding

features of GFRP include high corrosion resistance, high fatigue resistance, low density, and high tensile strength.

The use of UFC slab on the GFRP I-beams can avoid premature delamination failure and increase both flexural

strength and stiffness of the GFRP I-beams. However, the relatively low stiffness of the GFRP I-beams becomes

one of the critical design limitation of GFRP bridges. The American Association of State Highway and

Transportation Officials (AASHTO) and the Japan Society of Civil Engineers (JSCE) suggest that the deflection

limit for pedestrian bridges should be less than L/500, where L corresponds to the bridge span. Therefore, it is

important to analyze the flexural behavior of GFRP-UFC composite beams prior to their application on a real

bridge. This paper describes the analysis of GFRP-UFC composite beams using a simple fiber model, which is

economical and less time-consuming. Large-scale four-point bending tests were conducted on GFRP-UFC

composite beams having different beam parameters and the experiment results were compared with the fiber model

analysis results. The fiber model results were agreed well with the experiment results.




FLEXURAL BEHAVIOUR OF AN INNOVATIVE CONNECTION FOR

STRUCTURAL SANDWICH PANELS

R. Lameiras 1, J. Barros2, I.B. Valente2 and M. Azenha2

1 University of Brasília – UnB, Campus Darcy Ribeiro, FT-ENC, Brasília, Brazil, email: [email protected]

2 University of Minho, Campus de Azurém, Guimarães, Portugal

KEYWORDS

Hybrid structures, Characterization of FRP and FRC materials/systems, Sandwich panel, Connector, PERFOFRP,

Flexural behaviour.

ABSTRACT

This paper presents the results of an experimental work conducted with composite beam specimens that are part

of a series of feasibility studies for a new type of shear connector, called PERFOFRP. The connector is applied in

Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC) structural sandwich wall panels. PERFOFRP

consisted of a flat Glass Fibre Reinforced Polymer (GFRP) plate with aligned holes evenly distributed along its

length. The perforated part of connector is embedded in the outer concrete layers and the connection is materialized

by the combined effects of friction/adhesion and mechanical interlock between the perforated laminate and the

concrete dowels formed by the concrete that pass through the holes. In previous works, the authors this paper

investigated the mechanical behaviour of connections made with PERFOFRP connectors under transversal loads.

The flexural behaviour of sandwich panels produced with the PERFOFRP connectors is a subject that has not yet

been reported. In such context, this paper pertains to research on the overall mechanical behaviour of the

connection under flexure with explicit focus on: failure modes, stiffness and ultimate flexural capacities of

composite beams. Further focus is given to the impact of using connectors made with two different types of GFRP

laminates on the mechanical behaviour of composite beams.





BEHAVIOUR OF CONCRETE SANDWICH WALL PANELS IN FLEXURE USING A

NOVEL GFRP SHEAR CONNECTOR

Debrup Dutta1, Amir Fam2 1Queen’s University, Department of Civil Engineering, Kingston, Canada ([email protected])

2Queen’s University, Department of Civil Engineering, Kingston, Canada ([email protected])

KEYWORDS

Sandwich panels, Composite action, Shear connector, Concrete wythe, Thermal bridging, Pultruded sections.

ABSTRACT

This paper investigates the structural behaviour of three half-scale concrete sandwich panels with a new GFRP

shear connector, under four-point bending. The connector attempts to maximize the degree of composite action

between the two concrete wythes while maintaining a minimal thermal bridging, compared to steel connectors.

The overall dimensions of the specimens are 3048 mm x 610 mm x 279 mm. Each concrete wythe is 76 mm thick

and are separated by a 127 mm thick Extruded Polystyrene (XPS) foam layer in between the wythes. The GFRP

shear connector is a 203 mm deep C-shaped pultruded channel located at mid-width of the specimens and its two

flanges are embedded at mid thickness of the concrete wythes (Figure 1). The first specimen was fabricated using

a flexural steel reinforcement ratio of 0.34% in its concrete wythes, while the second specimen was fabricated with

a steel ratio of 0.68%, with the aim to study the effects of change of reinforcement ratio in the slab system. In both

specimens the same GFRP connector, in the form of one continuous GFRP section, was used. The last specimen

was fabricated using a conventional steel truss shear connector system with a cross sectional stiffness of the

diagonals equivalent to the GFRP C-section and the same steel reinforcement ratio in the wythes as the first

specimen. The aim was to compare the two different shear connectors. It was found that the GFRP connector

resulted in a flexural strength 2.85 times that of the specimen with steel truss system. Also, doubling the steel

reinforcement ratio of the wythe increased flexural capacity by 40% when GFRP connectors were used.

Figure 1: Test setup and instrumentation (dimensions in mm)






HOW MUCH DAMAGE CAN FRP TUBE TOLERATE IN CFFT?

Chenxi Lu 1, James St. Onge 2 and Amir Fam 3

1 MASc. Student, Department of Civil Engineering, Queen’s University, Canada, Ellis Hall, 58 University

Avenue, Kingston, K7L 3N6, Canada, Email: [email protected]

2 PhD. Candidate, Department of Civil Engineering, Queen’s University, Canada,

Ellis Hall, 58 University Avenue, Kingston, K7L 3N6, Canada, Email : [email protected]

3 Associate Dean of Research and Graduate Studies, Donald and Sarah Munro Chair in Engineering and

Applied Science, Professor Department of Civil Engineering, Queen’s University, Canada, Ellis Hall, 58

University Avenue, Kingston, K7L 3N6, Canada, Email: [email protected].

KEYWORDS

Concrete-filled, FRP tube, damage, cut, section loss, flexure

ABSTRACT

Concrete-filled FRP tube (CFFT) is an attractive system suitable for structural applications such as columns, piles,

poles and arches. The tube is a stay-in-place structural form that fully or partially replaces internal reinforcement.

Layers or fibres oriented at various directions provide great flexibility and control of the strength and stiffness in

the longitudinal and circumferential directions. One vulnerability of the system is that the FRP tube, being external,

is exposed. As such, it is possibly vulnerable to accidental or intentional damage. This study is the first of its kind

to address this concern. Damage is simulated by a controlled narrow cut of the tube throughout its full thickness.

The extent of damage is represented by the length of the cut. The objective is to establish the threshold of damage

beyond which significant strength loss of the CFFT member is observed. The findings of the work will help inform

important decisions made by engineers, for example shutting down a bridge or a building to remove live loads, or

alternatively conducting the repair work while the structure is in service. This paper focuses on flexural

performance of damaged CFFTs, while the next phase of the study will focus on axial compression members.

Seven CFFT specimens of 113 mm-diameter were fabricated and tested under four-point bending. One CFFT was

tested fully intact as a control specimen. The other six CFFTs were cut at mid-span on the tension side to eliminate

the primary contributing fibres in tension. Five were cut in the circumferential direction, one in the longitudinal

direction and one had a square cut. The length of the cut varies as a percentage of the perimeter of the tube. The

results showed that a 3% circumferential cut in tension results in nearly 50% loss of ultimate moment, however,

the rate of reduction in strength is much lower at longer length cuts (Figure 1). For the tube used in this study, the

critical circumferential cut length that can be sustained by the CFFT was found to be 29% of the tube perimeter,

after which the member should be taken out of service.

Figure 1: Test setup and summary of results





DOUBLY-CURVED SANDWICH PANELS WITH UHPC-FACINGS

Alexander Stark1, Christian Knorrek1, Sophia Perse1

1 RWTH Aachen University, Institute of Structural Concrete, Aachen, Germany


KEYWORDS :

Sandwich constructions, CFRP, UHPFRC, PU, foamed polyurethane, production methods.

ABSTRACT:

The demands on contemporary buildings make new construction methods and materials necessary. Sandwich

elements with layers made of high performance concrete and additional specialised characteristics can fulfil the

requirements of sustainable and durable building envelopes. The application of two thin doubly-curved facings

made of high performance concrete and a core of polymeric rigid foam can highly enhance the load-bearing

capacity of the sandwich panel providing a low weight at the same time. Due to the corrosion resistance, pre-

tensioned CFRP (Carbon fiber reinforced polymer) reinforcement was used to enable long spans. The use of UHPC

(ultra-high performance concrete) with high compressive and tensile strengths results in a reduction in concrete

usage and the realisation of slender panels.

The paper reports on the production and experimental investigations on doubly-curved sandwich panels with

UHPC facings and pre-tensioned CFRP tendons (Fig. 1). An adjusted formwork and prestressing frame were

produced to allow for smooth concrete surfaces and pre-tensioned CFRP tendons. The core material (PU) was

foamed in pack between the hardened concrete layers to achieve a homogeneous bond quality and account for the

curved shape of the facings.

The doubly-curved sandwich panels were tested under flexural loading.

Figure 1: Doubly-Curved Sandwich Panels




LARGE-SCALE SLENDER HYBRID FRP-CONCRETE-STEEL DOUBLE SKIN

TUBULAR COLUMNS SUBJECTED TO ECCENTRIC COMPRESSION

P. Xie1,2, T. Jiang3 and J.G. Teng2,* 1 Department of Civil Engineering, South China Agriculture University, Guangzhou, China;

2 Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong,

China,*Email: [email protected] 3 Department of Civil Engineering, Zhejiang University, Hangzhou, China,

KEYWORDS :

Hybrid structures; Experimental study ; Characterization of FRP and FRC materials/systems; Eccentric

compression; Slenderness

ABSTRACT

Hybrid FRP-concrete-steel double skin tubular columns (hybrid DSTCs) are a new and promising form of columns

that exhibits excellent structural performance and corrosion resistance. Previous studies on hybrid DSTCs have

mainly been limited to small-scale specimens and paid limited attention to the behavior of eccentrically-loaded

slender hybrid DSTCs. This paper presents the test results of two eccentrically-loaded large-scale hybrid DSTCs,

including one short column and one slender column, of a larger test program aimed at investigating the behavior

of large-scale slender hybrid DSTCs subjected to eccentric compression. A comparison of test results of the two

columns reveals clearly the effect of slenderness on the load–carrying capacity and failure mode of eccentrically-

loaded hybrid DSTCs. To capture the effect of slenderness on the behavior of eccentrically-loaded hybrid DSTCs,

a theoretical column model, which traces the lateral deflection of columns using the numerical integration method

and incorporates an eccentricity-dependent stress-strain model for concrete in hybrid DSTCs, was developed. It is

shown that the column model is accurate in predicting the load-carrying capacity of hybrid DSTCs and reasonably

accurate in predicting the lateral deflection of hybrid DSTCs.





EXPERIMENTAL INVESTIGATION OF A NEW PRECAST BEAM-COLUMN

CONNECTION FOR CONCRETE-FILLED FRP TUBES (CFFTS)

Ahmed M. Ali 1, Radhouane Masmoudi 2

1 Université de Sherbrooke, (J1K 2R1), Canada, PhD Candidate, Email: [email protected]

2 Université de Sherbrooke (J1K 2R1), Canada, Professor, Email: [email protected]

KEYWORDS

Fiber-reinforced polymer, Concrete-filled FRP tubes, Precast CFFT connection, Beam-column connection,

Monotonic loading, Bond.

ABSTRACT

Concrete-filled fiber reinforced polymer (FRP) tube (CFFT) is a superior hybrid system regarding to its high

performance. Extensive research was studied the behavior of CFFTs as column or as beam separately. Very

limited data are available about how to connect CFFT beam and column together. This research is presenting a

new precast CFFT beam-column connection. The beam tube was a pultruded FRP tube and the column tube was

a filament-winding tube. The CFFT beam had not any internal reinforcement. The CFFT column had internal steel

reinforcement. The connection part was consisted of hollow rectangular steel beam welded to steel end plate. The

beam tube was filled with normal strength concrete. After it hardened, the CFFT beam was embedded into the

rectangular steel beam. The gap between the steel connection and the CFFT beam was filled with epoxy-grout.

The end plate of the steel connection has eight holes. The column tube was prepared to have the same position

and number of the steel end plate holes. The steel cage of the column was inserted in the tube then the tube was

filled with concrete. After the CFFT column hardened, the beam was bolted to the column using eight steel rods,

4 in the tension side and 4 in the compression side. This CFFT beam-column connection was tested under

monotonic loading. The experimental results indicated that the failure occurred on the tension side of the CFFT

beam in flexural failure manner. The slippage between the CFFT beam and the grout was measured, also between

the grout and the steel connection.



MOMENT-CURVATURE CHARACTERISTIC OF STEEL AND CFRP

REINFORCED CFFT COLUMNS: EXPERIMENTAL AND THEORETICAL STUDY

Maha Hussein Abdallah1, Hamdy M. Mohamed2, Radhouane Masmoudi3, Ahmed Moussa4

1 PhD candidate Department of Civil Engineering, University of Sherbrooke, Quebec, Canada, J1K2R1.

[email protected]

2 Research Associate-Lecturer, Department of Civil Engineering, University of Sherbrooke, Quebec, Canada,

J1K2R1. [email protected]

3 Professor of Civil Engineering Department of Civil Engineering University of Sherbrooke, Quebec, Canada,

J1K2R1, [email protected].

4 Professor of Concrete Structures, and former Dean, Helwan University.

Dean of faculty of Engineering, Badr University in Cairo, BUC, E-mail: [email protected].

KEYWORD

Concrete, Eccentricity, Columns, Moment-Curvature.

ABSTRACT

The paper highlights the investigation of experimental and theoretical moment-curvature relationships for circular

steel and carbon-fiber-reinforced polymers (CFRP) reinforced concrete-filled FRP tube (CFFT) columns. To

experimentally investigate the moment curvature behavior of circular CFFT columns, Steel reinforced CFFT and

CFRP reinforced CFFT columns were tested under eccentric loads. It was found that a nonlinear moment-

curvature (M-ɸ) response was observed regardless the type of reinforcement and the applied eccentricity ratio. A

theoretical model based on layer by layer method has been developed to investigate the theoretical behavior of

CFFT columns. Material constitutive models of each component of the column have been chosen adequately to

insure the accuracy of the developed model. The analytical model has been validated with the experimental results

and proved to be an accurate model.



BEHAVIOR OF GFRP WALL PANEL WITH INTERNAL TUNED LIQUID COLUMN

DAMPER

H. Wu 1, A. Chen 2 and S. Laflamme 3 1 Iowa State University. Department of Civil, Construction and Environmental Engineering, USA,

Email: [email protected]; 2 Iowa State University. Department of Civil, Construction and Environmental Engineering, USA,

Email: [email protected];

3 Iowa State University. Department of Civil, Construction and Environmental Engineering, Department of

Electrical and Computer Engineering, USA, Email: [email protected].

ABSTRACT

Pultruded Glass Fiber-Reinforced Polymer (GFRP) structures have been increasingly used in buildings and civil

infrastructure systems because of their high strength, light weight, durability, and fatigue resistance. However,

these structures are elastic and typically have low damping ratio, which limits their capability to dissipate energy

during earthquakes. Adding damping mechanisms to GFRP components can improve traditional structures’

resistance to lateral loads. This paper studies a cellular GFRP wall panel with an internal liquid flow system,

engineered to control a structure’s temperature using liquid as thermal exchange. In this study, we further adapt

the panel to allow oscillation of water in its internal hollow cells, providing supplemental damping for the GFRP

structure during seismic events. Different combinations of water heights and cell openings are evaluated using

shaking table tests to study vibration reduction of the GFRP wall panel by leveraging the motion of water. For

each combination, the natural frequency of TLCD can be predicted with a simple model. It is found that higher

water volume inside the panel can achieve greater mitigation. A Computational Fluid Dynamics (CFD) model is

created to study the liquid motion inside the GFRP panel under harmonic ground excitations. Results from the

CFD simulation are in good agreement with those from the test.






Timber and FRP




MECHANICAL BEHAVIOR OF HYBRIDAL FLOOR PANELS TO TIMBER

COLUMNS JOINTS

Magdalini Titirla 1, Laurent Michel 1, Emmanuel Ferrier 1

1 Laboratoire des Matériaux Composites pour la Construction, LMC², Université LYON 1, 82 boulevard Niels

BOHR, Site de Villeurbanne DOUA, 69622 VILLEURBANNE Cedex - FRANCE;

KEYWORDS :

Hybrid structures; Experimental study ; FRP internal reinforcement;

ABSTRACT:

The aim of the present paper is the experimental investigation of five different types of joints between concrete-

timber hybrid panels and timber columns. The five connections presented in Figure 1. Each panel consists of

Glulam timber and/or Concrete members with timber and concrete beams and concrete cladding. The first

connection type incorporates a dowel-type column that jointed to the beam through long bolts, while the second

one is a steel plate slotted into the timber beam and timber columns connected to them by means of transverse

bolts. The other three connection types are far from the bolted connections, as the third connection type

incorporates a steel rebar connection in UHPFRC concrete, the fourth one is made of Carbon FRP rebar in glulam

both in the timber and concrete part of the beams, while the fifth one connected by Glass FRP rebar in glulam

both. The experimental set-ups of all the connections is subjected to monotonically increasing bending action, and

there are conducted at the premises of Laboratory for Composite Materials and Composite Structures of the

University Claude Bernard Lyon I.

Figure 1: The five proposed connections that experimentally investigated.



104


BOND ANALYSIS OF BASALT FIBRE REINFORCED POLYMER (BFRP) BARS

AND TIMBER BEAMS UNDER AXIAL LOADING

D. Walline 1 and A. Rteil 2

1 The University of British Columbia, School of Engineering, 3333 University Way, Kelowna, BC, V1V 1V7,

Canada, Email: [email protected]

2 The University of British Columbia, School of Engineering, 3333 University Way, Kelowna, BC, V1V 1V7,

Canada, Email: [email protected]

KEYWORDS

Strengthening and repair, experimental study, bond and interfacial stresses, timber beams, development length,

fibre reinforced polymer (FRP)

ABSTRACT

Flexural reinforcement of damaged or deteriorated timber beam using fibre reinforced polymer (FRP) bars is a

potentially attractive solution to extend the service life of aged or historic timber structures. However, to ensure

full utilization of the FRP, the bond between the two materials must be strong enough to reach the ultimate strength

of the FRP bars. This paper details the investigation of the effects of bar size and bond length on the bond strength

of basalt FRP bars and Douglas Fir timber beams under axial loading. A total of 18 double shear specimens were

tested (shown in Figure 1). Both parameters were determined to be statistically significant and an empirical model

was proposed. From the empirical model, a bonded length of 467 mm and 1938 mm would be required to prompt

bar failure for 6 mm and 10 mm bars respectively.

Figure 2: 3D model of double shear specimens



105


COMPRESSIVE BEHAVIOR OF MEDIUM STRENGTH CIRCULAR GLUE

LAMINATED TIMBER COLUMNS JACKETED WITH FRP SHEETS

Omer Asim SISMAN1, Ali ISIKARA2, Ergun BINBIR3 and Alper ILKI4

1 Senior Student, Civil Engineering Faculty, Istanbul Technical University, Istanbul, Turkey

2 Master Student, Energy Institute, Istanbul Technical University, Istanbul, Turkey

3 PhD Candidate, Civil Engineering Faculty, Istanbul Technical University, Istanbul, Turkey

4 Professor, Civil Engineering Faculty, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey. E-mail:

[email protected]

KEYWORDS:

CFRP; Compression; Fiber reinforced polymers; Glulam; Timber columns.

ABSTRACT:

Glue laminated timber (glulam) is an aesthetical, natural, energy saving and sustainable construction material that

is a renewable, easily applicable and lightweight alternative in low and medium rise buildings, unlike steel and

other reinforced concrete structural elements. In high-rise buildings, however, high strength and ductile columns

and long-span beams are required. To meet these requirements, mechanical properties of timber are enhanced by

minimizing the effects of initial defects, knots and discontinuities in the wood and protecting against deterioration

caused by moisture and weathering that result in splitting, cracks, insect damage and fungal decay. Use of fiber

reinforced polymer (FRP) sheets is also among potential promising approaches to improve mechanical

performance of timber members. This paper presents compression test results of medium strength circular glulam

columns externally jacketed with carbon fiber reinforced polymer (CFRP) sheets to enhance the structural

behaviour of timber columns. In the experimental program, 6 reference and 6 externally jacketed circular glulam

columns were prepared with three different diameters and tested under uniaxial compression loading (Figure 1).

The aim of this research is to investigate the failure modes and to obtain stress-strain relationships of these columns

before and after jacketing with CFRP sheets. The external jacketing of glulam columns with CFRP sheets has

resulted in significant improvement in deformability. However, in contrast, the confinement effect was not that

significant for some strengthened specimens due to the presence of knots at the outer surface. In addition,

generally, there was a slight gain in compression strength due to external jacketing as well.

Figure 1: General appearance of the test setup


Composites


106


WIDTH EFFECT OF FRP EXTERNALLY BONDED TO TIMBER

Abbas Vahedian1, Dr Rijun Shrestha1, Prof Keith Crews1 1 School of Civil and Environmental Engineering, University of Technology, Sydney, Australia (corresponding

author: [email protected])

ABSTRACT:

Bond mechanism between timber and fibre reinforced polymer (FRP) composites is affected by a number of

variables. However, effect of parameters such as bond width, bond length, material properties and geometries on

the bond strength is not fully understood. This study investigates the influence of bond width on the bond strength

and failure mode of externally bonded FRP-to-timber interface. Pull-out tests on 136 FRP-to-timber joints with

different FRP widths were conducted. Results of experimental tests showed that the bond width has significant

effect on the bond strength; with the increase of FRP width, the interfacial bond strength increases. In addition, it

was observed that the maximum shear stress decreases with the increase of FRP-to-timber width ratio.

Furthermore, FRP-to-timber width ratio impacts on the local bond-slip in which slip of the bond reduces when this

ratio is increased.

KEYWORD: Bond strength, Width effect, LVL, FRP, Bond-Slip.


Composites


107


All FRP Structures



108


EXPERIMENTAL INVESTIGATION ON FLANGE LOCAL BUCKLING OF

PULTRUDED GFRP BOX-SECTION UNDER FLEXURE

Tianqiao Liu1 and Kent A. Harries1,2

1University of Pittsburgh, Civil and Environmental Engineering, Pittsburgh, USA ([email protected]) 2University of Bath, BRE Centre for Innovative Construction Materials, Bath, UK

KEYWORDS

All FRP and smart FRP structures; Experimental Study; Flange Local Buckling

ABSTRACT

Flexural stability of various pultruded glass fibre reinforced polymer (pGFRP) profiles, such as I-, C- and box-

sections, have been experimentally and analytically investigated in numerous studies in past decades. Flange local

buckling (FLB) behaviour of pGFRP box-sections subject to flexure, however, has not been sufficiently studied

through practical experiments. Consequently, a lack of data impedes the development and validation of theoretical

predictions of the critical FLB behaviour of box-sections. To augment the data for box-sections, an experimental

program, consisting of a series of four-point bending tests having various constant moment and shear span lengths,

was conducted to investigate the FLB behaviour of pGFRP box-sections having slender flanges subject to flexure.

The sections and loading patterns were intentionally selected to promote FLB behaviour. Additionally, in order to

accurately evaluate the mechanical properties of the specimens, material characterisation tests were carried out.

Experimentally determined critical FLB moments were contrasted with the analytical solution for an infinitely

long plate supported at its edges subject to uniform compression. Variations of this solution are used by all known

design guides. The lower bound prediction, using measured material properties provided a reasonable and suitably

conservative estimate of actual behaviour for the 102 x 152 x 6.4 mm box sections tested.



109


LONG-TERM DESIGN OF GFRP-PUR WEB-CORE

SANDWICH STRUCTURES

Sonia Yanes-Armas1, Julia de Castro1, Thomas Keller1 1 Ecole Polytechnique Fédérale de Lausanne (EPFL), Composite Construction Laboratory (CCLab), Lausanne,

Switzerland (corresponding author: [email protected])

KEYWORDS :

Sandwich structures; Web-core sandwich; Creep ; Polyurethane foam; Codes, standards and design guidelines

ABSTRACT:

The structural behavior of GFRP-polyurethane (PUR) web-core sandwich structures subjected to sustained loading

was investigated. The approach followed in currently available design guidelines for FRP sandwich structures to

consider the PUR foam creep behavior in structural design was first addressed and discussed. It was shown that

creep parameters proposed in design recommendations differ from equivalent experimental ones and may result

in an unconservative design for long-term loading. The influence of creep on the web-core interaction, i.e. on the

shear load distribution and local instability phenomena were then analyzed. The effects of applying particular

design recommendations on the design were assessed based on the example of a real GFRP-PUR sandwich roof.

The design shear resistance of the GFRP webs, their dimensions and governing failure mode significantly

depended on the applied recommendation. The overall shear resistance of the GFRP-PUR core over time, taking

into account creep effects, was further evaluated. It was demonstrated that considering the summation of the

components’ individual resistances results in an unsafe design. A design procedure to take this into account was

established.

Figure 1 : Novartis Campus Entrance Building, GFRP-PUR sandwich roof, Switzerland, 2006; (a) view from the

south; (b) four-point bending set-up of roof sandwich beam, Keller et al. (2008).

Figure 2: Comparison of shear modulus reduction factor for 50-kg/m3 PUR foam calculated according to BÜV

recommendation and experimentally determined.

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105

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110


Figure 3: Design shear (d) and shear wrinkling (wr,d) strength of GFRP webs according to different design

recommendations.

Figure 4: (a) Time-dependent contribution of web-core components to shear stiffness and resistance; (b) time-

dependent normalized shear resistance of hybrid core and individual components from case study.

10-3

10-2

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100

101

102

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105

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Verification Eurocomp BÜV EUR 27666

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Core components:

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Web failure for t > t

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Change of



111


MULTI-OBJECTIVE OPTIMIZATION OF A COMPOSITE SANDWICH PANEL

FLOOR SYSTEM FOR BUILDING REHABILITATION

Mário Garrido1, José F.A. Madeira2,3, Miguel Proença1, João R. Correia1 1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; 2 IDMEC, Instituto Superior

Técnico, Universidade de Lisboa, Lisbon Portugal; 3 ISEL, Department of Mathematics, IPL, Lisbon, Portugal


KEYWORDS:

composite sandwich panels; multi-objective optimization; building floors; structural rehabilitation; cost

minimization; carbon footprint minimization

ABSTRACT:

Composite sandwich panels are being increasingly considered for structural applications in civil engineering.

However, their high versatility regarding possible constituent materials and geometrical arrangement translates to

a high number of design variables. Additionally, there is a potentially large number of design requirements and

objectives related to the panels’ functions. This paper presents an optimization study of a composite sandwich

panel floor system for use in building rehabilitation. Pultruded multicellular panels with a polyurethane (PUR)

foam core and carbon- or glass-fibre reinforced polymer (C/GFRPF) faces and ribs/webs are considered (Figure

1). The Direct MultiSearch (DMS) optimization method is adopted. The panel architecture is defined using 3

geometrical variables and 14 material related variables. In addition, 8 competing objective functions are studied,

related to different aspects, such as structural serviceability and resistance, thermal insulation, acoustic

performance, cost minimization, and environmental performance. The results are presented in the form of Pareto

optimal sets, from which several conclusions are drawn regarding common design-related options. The influence

of core material density, number of ribs/webs or the type of fibre reinforcement and its respective layup on the

different objective functions is addressed. Optimal solutions for meeting different design purposes are presented,

providing useful insights for structural designers and composite sandwich panel manufacturers.

Figure 1: Generic cross-section of the considered sandwich panels



112


DEVELOPMENT OF A SNAP-FIT CONNECTION SYSTEM BETWEEN

PULTRUDED GFRP SANDWICH PANELS FOR BUILDING FLOORS

Miguel Proença1, Mário Garrido1, João R. Correia1 1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal (corresponding author:

[email protected])

KEYWORDS:

composite sandwich panels; building floors; connections; snap-fit

ABSTRACT:

This study presents the development of a snap-fit connection system to join FRP composite sandwich panels

produced by pultrusion. The panels were developed for the replacement of degraded timber floors in old buildings,

where restrictions in the available on-site space are often encountered, limiting the maximum size and weight of

the sandwich panels. A preliminary design was made and used as baseline for a parametric study on the influence

of the joint geometry in the deformability and behaviour of the connection. Finite element (FE) models were

developed for this purpose, simulating two connected sandwich panels loaded along their transverse direction. The

force required for the assembly of the snap-fit joint taking into account the geometric clearances, and the stresses

and strains resulting from the joining operation, were analytically predicted. An FE model of a floor composed of

sandwich panels connected using the developed snap-fit system was used to predict the load distribution along the

main floor spans, as well as maximum deflections and stress vs. strain profiles in the panels (Figure 1). The

parametric study provided a better understanding of the influence of different parameters concerning the snap-fit

in the joints’ deformability. The study of the assembly forces indicated the advantage of adopting longer latches

in order to reduce the mating forces and induced deformations. The results obtained show that those forces should

enable the use of only manual labour for the execution of the connections, and that the joints should exhibit

sufficient stiffness and strength to guarantee an adequate structural performance of the composite floor, promoting

the distribution of loads along the main directions of the sandwich panels.

Figure 1: General view of the floor deformed shape (left) and detail of the deformations and axial stresses in the

transverse direction (represented as “S11”, in MPa, right) at a snap-fit connection



113


FORM-FINDING AND STRUCTURAL DESIGN OF AN ARCHITECTURAL

SCENERY WITH ALL GFRP FREE-FORM FACADE

Yuchao ZHAO1, Xu JIANG 1, Qilin ZHANG 1, Qi WANG 1 1 Tongji University, College of Civil Engineering, Shanghai, China; (Xu JIANG: [email protected])

KEYWORDS :

GFRP; Free form curved facade ; Processing technology; Secondary girders

ABSTRACT:

With the pursue of architecture artistic effect improving rapidly all around the world, constructions with curved

facade were built one after another. This gives a challenge to the construction skills of facade, and also exposes

the weakness of traditional materials when applying to curve surface modelling. GFRP (Glass-Fibre-Reinforced

Polymer), as an emerging building material, has advantages on plenty of aspects over traditional materials, especial

on processability. Thus it is an extremely ideal free form surface modelling material and possible to provide an

excellent solution to curved architecture facade. The architecture schematic design of a sunken plaza covering

structure in Fuzhou, China is a sculptural shaped construction similar to three trumpet flowers. The whole design

presents an obvious warping shape from the top view, thus its surface is complicated and completely in free form

curve. The owner's demand for the final effect of the structure is pretty high, so traditional materials were

abandoned since they cannot meet the demand and GFRP are selected as facade material finally. There are three

main problems are encountered in detailed designing and processing stage of GFRP: a. processing technology of

free-form surface panels for mass production; b. the selection and layout of secondary girders which support

panels; c. the connection problem between GFRP panels and secondary girders. The contradiction points and

solving process of these three main practical problems are discussed in this paper and solutions are listed, thus

similar problems encountered in the future can be further directed.

Figure 1: Secondary girders



114


MONOTONIC AND CYCLIC BEHAVIOUR OF BEAM-TO-COLUMN BOLTED

METALLIC-CUFF JOINTS BETWEEN PULTRUDED GFRP PROFILES

David Martins1, João Azevedo1, José A. Gonilha1, João R. Correia1, Mário Arruda1, Nuno Silvestre2 1 CERIS, Instituto Superior Técnico, University of Lisbon, Portugal; 2 IDMEC, Instituto Superior Técnico,

University of Lisbon, Portugal (corresponding author: [email protected])

KEYWORDS :

All FRP and smart FRP structures; Experimental study ; Seismic applications; Characterization of FRP and FRC

materials/systems; Beam-to-column connections

ABSTRACT:

Owing to their high strength, light-weight and corrosion resistance, pultruded glass fibre reinforced polymer

(GFRP) profiles have been pointed out as a promising alternative to traditional structural materials. Nevertheless,

widespread use has been hindered by their brittle behaviour, low elastic moduli and lack of widely accepted design

guidelines. The connection technology for GFRP frame structures, which must account for the linear-elastic

behaviour at the material level and has a significant influence on the overall deformability of pultruded GFRP

members, is still relatively underdeveloped.

This paper presents the development of a novel beam-to-column connection system for GFRP tubular profiles

comprising an external thin-sheet metallic cuff. Aiming at the development of ductile or pseudo-ductile connection

systems, envisaging the inelastic energy dissipation under cyclic loads and, thereafter, the development of GFRP

frame structures with adequate seismic performance, 2 mm steel cuffs were tailored to 120 mm square tubular

profiles, being bolted to the beam’s (i) web or (i) flanges. The experimental programme comprised (i) monotonic

and (ii) cyclic tests on these beam-to-column joints (Figure 1). The results show that the steel cuff is a promising

structural solution for GFRP beam-to-column connections, providing an enhanced performance, in terms of

strength and stiffness, when compared to other connection systems previously tested by the authors. Moreover,

the test results show that this connection system provides considerable ductility (monotonic tests) and ability to

dissipate energy (cyclic tests), despite the pinching effect (Figure 2).

Figure 1: Test setup of GFRP beam-to-column

steel-cuff joints.

Figure 2: Results of monotonic (WM2) and cyclic (WC1)

tests of web-bolted specimens.



115


INDENTATION AND IMPACT BEHAVIOUR OF COMPOSITE SANDWICH PANELS

FOR CIVIL ENGINEERING STRUCTURAL APPLICATIONS

Rui Teixeira1, Mário Garrido1, Miguel Proença1, João R. Correia1, Leigh Sutherland2 1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; 2 CENTEC, Instituto Superior

Técnico, Universidade de Lisboa, Lisbon, Portugal (corresponding author: [email protected])

KEYWORDS:

composite sandwich panels; building floors; indentation; impact

ABSTRACT:

Composite sandwich panels are a promising solution for the rehabilitation of building floors and pedestrian

bridges. However, previous studies on relatively thin sandwich panels have pointed out their particular

susceptibility to concentrated loads. In this respect, studies developed for relatively thick sandwich panels such as

those used in civil engineering structural applications are scarce. The present work presents an experimental,

numerical and analytical study of the indentation/punching and perforation behaviour of relatively thick GFRP

composite sandwich panels under concentrated loads. In the experimental study, the effects of the indenter

geometry (shape and diameter) and of different core materials (PUR and PET foams and balsa wood) on the

indentation stiffness, first damage and peak resistances, and energy absorption capacity of the sandwich panels are

investigated. The results obtained show that the present type of sandwich panels, despite exhibiting high resistance

values, present a relatively low energy absorption capacity up to first damage. Indenter geometry was the most

influential parameter for the low-velocity impact behaviour of these thick FRP composite sandwich panels. The

indentation stiffness was mainly influenced by the core material, but the effect of this on impact resistance was

less marked. Quasi-static tests provided a conservative estimate for the impact behaviour of composite sandwich

panels. The numerical study comprised the development of 3D finite element models of the sandwich panels,

concluding that the Hashin (failure initiation) criterion gives a very reasonable prediction of the first damage

resistance (12% relative difference compared to the test value selected as a case study). For the two analytical

models analysed, a parametric study was completed and a new formulation was proposed; the results obtained

showed that the models can provide very reasonable predictions of first damage resistance.

Figure 1: (a) Quasi-static indentation test setup; and damage caused by the action of (b) hemispherical and

(c) flat indenters

(b) (a) (c)



116


EXPERIMENTAL STUDY ON SHEAR PROPERTIES OF GFRP CHANNEL

MEMBER

Yuanbin Wang 1, Hitoshi Nakamura 1, Yuya Ishii 2, Yutaro Inari 3, Hiroshi Nakai 4, Masayuki Nishida 5 1 Tokyo Metropolitan University, Department of Civil and Environmental Engineering, Hachioji-shi, Japan 2 Tokyo Metropolitan University, Department of Civil and Environmental Engineering, Hachioji-shi, Japan

3 East Nippon Expressway Co., Ltd., Saku-shi, Japan 4 Nippon Expressway Research Institute Co., Ltd., Machida-shi, Japan

5 Maedakosen Co., Ltd., Chuo-ku, Japan 6 Nihon FRP Co., Ltd., Osaka-shi, Japan

KEYWORDS:

GFRP channel member; Unidirectional material; Experimental study; Shear modulus; Shear strength

ABSTRACT:

A pultruded GFRP made of unidirectional material is a typical material for FRP structures, for example, a

footbridge, inspection path, hydraulic gate, etc. The properties of tensile, compression and bending have been

investigated in pultruded GFRPs. However, the shear properties were not clarified sufficiently, nevertheless shear

failures were often observed. In study, shear properties and evaluation method of pultruded GFRP made of

unidirectional materials (Channel member; C75) were investigated experimentally. The several shear tests were

conducted using the coupon and beam specimens for shear properties. In the V-notched beam method based on

ASTM D 5379, it was found that the shear properties were equivalent of the result of the beam test. The short

beam specimens were conducted by 3-point bending test. As a result, shear failures occurred in the shear span and

shear strength was properly and easily evaluated by short beam test, Therefore, the V-notched beam method was

proper method for evaluation of shear properties of pultruded unidirectional GFRP members.



117


DIC STRAIN FIELD MEASUREMENT OF FRP PLATES WITH AND WITHOUT

HOLES

Brad C. McCoy, P.E.1, Rudolf Seracino, Ph.D. 1, Gregory W. Lucier, Ph.D. 1, Timothy W. Langerhans2 1 North Carolina State University, Department of Civil, Construction, and Environmental Engineering, Raleigh,

North Carolina, United States (Email: [email protected]) 2 United States Military Academy, Department of Civil and Mechanical Engineering, West Point, New York,

United States

KEYWORDS :

Strengthening and Repair; Material; Digital Image Correlation; Mechanically Fastened-FRP

ABSTRACT:

This paper examines the results of material testing of hybrid glass/carbon fiber reinforced polymer (FRP) plates

for use in mechanically fastened applications. The small-scale material tests were conducted in three phases: 1)

uniaxial tension without holes, 2) uniaxial tension with open holes, and 3) uniaxial tension with bolted connections.

In all three phases of testing, Digital Image Correlation (DIC) was used to obtain continuous strain data, showing

holistic strain field development through failure. The high-resolution strain data provides detailed information for

the design of an efficient hole pattern in Mechanically Fastened-Fiber Reinforced Polymer (MF-FRP) plates. The

tests presented here are an initial phase of a larger project that aims to employ prestressed MF-FRP plates as a

repair for deteriorated prestressed hollow-core bridge slabs. Candidate slabs are those that have exposed tendons

such that the bridge is typically load posted. It is proposed that the use of a prestressed MF-FRP repair will restore

lost performance until replacement can be scheduled in a way that is cost effective, rapid, and enables periodic

inspection over the lifespan of the short-term repair – prior to scheduled superstructure replacement. The use of

prestressed MF-FRP in this application will eliminate the need for an adhesive bond and QA/QC concerns that are

often associated with externally bonded FRP.

Figure 1: Example DIC strain field

eyy exy




118


LOCAL BUCKLING OF PULTRUDED GFRP I-SECTION UNDER FLEXURE

Everton Souza1, Janine Vieira 2, Daniel Cardoso1 1 Pontifical Catholic University of Rio de Janeiro, Department of Civil and Environmental Engineering, Rio de

Janeiro, Brazil; 2

Fluminense Federal University, Department of Civil Engineering, Niteroi, Brazil. (corresponding author:

[email protected] )

KEYWORDS :


Codes, standards and design guidelines

ABSTRACT:

The use of pultruded glass fiber reinforced polymer (pGFRP) has increased significantly in the last few years,

especially in aggressive environments. The structural performance of pGFRP members is strongly dependent on

their buckling behavior, because of the association of low elastic properties and relatively thin-walled sections

adopted. The aim of this study is to present the results of an ongoing experimental work focused on evaluating the

local buckling behavior of GFRP I-beams subject to 4-point bending tests. Lateral deflections were measured with

displacement transducers and the curvature at compression flange during loading was measured with back-to-back

strain gages. A finite element model using actual material properties and bracing conditions was adopted to ensure

behavior governed by local buckling and to determine critical bending moment. The influence of web-to-flange

rotational stiffness on the behaviour is discussed and, finally, experimental critical loads obtained using Southwell

and Koiter techniques are compared to those obtained using analytical expressions recently proposed in literature

and to computational analysis.




119


ADAPTIVE REUSE OF FRP COMPOSITE WIND TURBINE BLADES FOR CIVIL

INFRASTRUCTURE CONSTRUCTION

R. Gentry 1, L. Bank 2, J. F. Chen 3, F. Arias 2, and T. Al-Haddad 1 1 Georgia Institute of Technology, School of Architecture, Atlanta, GA 30332 USA

Email: [email protected] 2 City College of New York, New York, NY, USA

3 Queen’s University Belfast, Northern Ireland, UK

KEYWORDS

Recycling of FRP Composites, Adaptive Reuse, Design of FRP Structures, Composite Wind Turbine Blades

ABSTRACT

The rapid growth in wind energy technology has led to an increase in the amount of thermosetting FRP composite

materials used in wind turbine blades that will need to be recycled or disposed of in the near future. Calculations

show that 16.8 million tons of waste from wind blades will need to be managed globally by 2030, increasing to

39.8 million tons by 2050. Three waste management route are possible: disposal, recycling or reusing. Currently,

most FRP composites taken out of service are disposal of in landfills or are incinerated. Recycling options consist

of reclamation of the constituent fibers or the resins by thermo–chemical methods or recycling of small pieces of

granular FRP material as filler material by cutting, shredding or grinding. Reuse options consist of reusing the

entire FRP blade or large parts of the blade in new structural applications.

This paper reports on the potential for reusing parts of wind turbine blades in new or retrofitted architectural and

civil infrastructure projects. The paper introduces the geometry, materials, and laminates typically used in wind

blades and provides a snapshot of the sizes of wind blades likely to be available from the inventory of active

turbines. Because the materials and manufacturing of commercial wind blades are proprietary, generic blade

geometries and materials are discussed. These come from the Sandia National Laboratory and National Renewable

Energy Laboratory, in the United States, and from OPTIMAT in the European Union. The paper presents an

example of the geometry and material properties of structural elements cut from wind blades, using the Numerical

Manufacturing and Design Tool (NUMAD), published by the Sandia National Laboratory.



120


DESCRIPTION & MATERIAL FACTOR OF FRP IN THE STANDARD

SPECIFICATION FOR HYBRID STRUCTURES 2014 BY JSCE

Itaru Nishizaki1, Hitoshi Nakamura2, Yasuo Kitane3, Takashi Matsumoto4, Kunitaro Hashimoto5, Akira

Kobayashi6 1 Public Works Research Institute, Innovative Materials & Resources Research Center (iMaRRC), Tsukuba,

Japan; 2 Tokyo Metropolitan University, Department of Civil & Environmental Engineering, Tokyo, Japan; 3

Nagoya University, Department of Civil & Environmental Engineering, Nagoya, Japan; 4 Hokkaido University,

Faculty of Engineering, Sapporo, Japan; 5 Kobe University, Department of Civil & Environmental Engineering,

Kobe, Japan; 6 Nippon Steel & Sumikin Materials Co., Ltd, Tokyo, Japan T


KEYWORDS :

Hybrid structures; Standard ; Codes, standards and design guidelines; Characterization of FRP and FRC

materials/systems, hybrid structures, standard specification, FRP, material factor, design, construction,

maintenance

ABSTRACT:

Japan Society of Civil Engineers (JSCE) has published the standard specifications for hybrid structures in 2014 as

its second revised edition. In the revised edition in 2014, FRP members and hybrid structures with FRP and

steel/concrete were also introduced as main structural types. In order to describe the standard methods of design,

construction and maintenance of structural FRP in the standard specifications, standard methods for the design,

construction and maintenance of FRP structures and FRP hybrid structures, and reliability and performance

evaluation methods of FRP members were studied by JSCE. The standard material factor was considered based

on the study on changes and dispersion of the mechanical properties of FRP materials. This paper introduces the

main description of FRP in the standard specifications of hybrid structures 2014, including the results of the study

on the changes of the performance of FRP members.

Figure 1 : Design flow and partial safety factors in the standard specifications 2014




121


FIBER MODEL ANALYSIS ON THE FLEXURAL BEHAVIORS OF

CFRP BOX BEAMS

Takashi Matsumoto1, Momoka Nasu2 1 Hokkaido University, Faculty of Engineering, Sapporo, Japan; 2 Hokkaido University, Graduate School of

Engineering, Sapporo, Japan

KEYWORDS :

All FRP and smart FRP structures; Modeling ; Characterization of FRP and FRC

ABSTRACT:

Carbon Fiber Reinforced Polymer, CFRP, is a promising structural material for the application to civil structures.

However, as CFRP beams show nonlinear and brittle behaviors at the ultimate state, it is necessary to develop a

method to obtain the deflection of CFRP beams by considering both the bending and shear deflection component.

This study aims to develop a fiber model analysis method to reproduce the behaviors of CFRP box beams that

have been tested in earlier experiments, and to verify the effectiveness of the method. CFRP box beams are

examined with two laminate structures, quasi-isotropic and cross-ply, and under four-point bending with three

different shear span cases. The bending deflection component is obtained by moment-area method, and the shear

deflection component is calculated based on Timoshenko’s beam theory. The shear strain of quasi-isotropic CFRP

is regarded as linear, whereas that of cross-ply CFRP as nonlinear, following the experimental observations.

Analytical results reproduce sufficiently the load-deflection relationships, showing the validity and the

effectiveness of the current analysis method developed.

(a) (b)

(c) (d)

Figure 1 : Load-deflection relationship (a) quasi-isotropic, (b) cross-ply (shear span 375mm), (c) cross-ply

(shear span 285mm), and (d) cross-ply (shear span 185mm)

2 4 6 8 10 12 14y mm

20

40

60

80

100

120

P kN

解析結果(部材計測)QI-1 (実験)QI-2 (実験)QI-3 (実験)0°層破壊 (解析)45°層破壊 (解析)90°層破壊 (解析)

Analysis(Beam)

QI-1(expt.)

QI-2(expt.)

QI-3(expt.)0°failure(analysis)

45°failure(analysis)


2 4 6 8 10 12 14y mm

20

40

60

80

100

120

P kN

解析結果(部材計測)解析結果(材料試験)

CP375-1 (実験)CP375-2 (実験)CP375-3 (実験)0°層破壊 (解析)90°層破壊 (解析)

CP375-1(expt.)

CP375-2(expt.)

CP375-3(expt.)0°failure(analysis)


Analysis(Beam)

Analysis(Material)

2 4 6 8 10 12 14y mm

20

40

60

80

100

120

P kN

解析結果(部材計測)解析結果(材料試験)CP285-1 (実験)CP285-2 (実験)CP285-3 (実験)0°層破壊 (解析)90°層破壊 (解析)

Analysis(Beam)

Analysis(Material)

CP285-1(expt.)

CP285-2(expt.)



2 4 6 8 10 12 14y mm

20

40

60

80

100

120

P kN

解析結果(部材計測)解析結果(材料試験)CP185-1 (実験)CP185-2 (実験)0°層破壊 (解析)90°層破壊 (解析)

Analysis(Beam)

Analysis(Material)

CP375-1(expt.)





122


PREDICTION OF THE WEB CRUSHING CAPACITY OF PULTRUDED GFRP I

SECTIONS UNDER TRANSVERSE LOADING

Xidong Wu 1,Chao Wu 1, * 1 School of Transportation Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191,


KEYWORDS

Web crushing; Transverse loading; Glass fiber reinforced polymer; Pultruded sections; Finite element analysis;

Prediction

ABSTRACT

Pultruded glass fiber reinforced polymer (GFRP) sections are prone to web crippling failure under concentrated

loading in the transverse direction to the pultrusion axis due to their low elastic and strength properties. This paper

reports an analytical and numerical study on the web crushing mechanism of pultruded GFRP I sections. Firstly,

finite element (FE) analysis was conducted using Abaqus. FE models were constructed using shell elements. Tsai-

Hill failure criterion was adopted to simulate the crushing failure of the I sections. Two transverse loading

conditions including interior two flanges (ITF) and end two flanges (ETF) were selected. The length of the bearing

plate and the height of the I section were varied to study their effects on the web crushing failure mechanism. The

results showed that the web crushing capacity was a linear function of the bearing length. It is also approximately

linearly correlated with the height of the section. Finally, an empirical equation for predicting the web crushing

capacity of the pultruded GFRP I section was proposed which agreed well with the existing experimental results

in the literature. This work contributes to a better understanding of the web crushing failure mechanism of

pultruded GFRP I section under transverse loading. .



123


EXPERIMENTAL STUDY ON THE WEB CRIPPLING BEHAVIOR OF PULTRUDED

GFRP CHANNEL SECTIONS

Li-Teng Zhang 1, Xi-Dong Wu 1 and Chao Wu 1, * 1 School of Transportation Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191,


KEYWORDS

Web crippling; Pultruded; Glass fiber reinforced polymer; Channel section; Transverse loading

ABSTRACT

Pultruded glass fibre reinforced polymer (GFRP) sections see increasing applications in civil constructions.

However, due to their inherent pultrusion manufacturing process, the pultruded GFRP sections are susceptible to

web crippling failure under concentrated transverse loading. This paper presents a preliminary experimental

investigation on the web crippling behaviour of pultruded GFRP channel sections. Three channel sections were

tested under two transverse loading conditions, namely end-two-flange (ETF) and interior-two-flange (ITF). Two

failure modes were observed including web buckling and failure at web-flange junction. It was found that the web

crippling capacities were not affected by the loading conditions when the failure was at the web-flange junction.

When the failure was web buckling, the web crippling capacities were more related to the web slenderness. This

paper contributes to enrich the experimental database of web crippling of pultruded GFRP channel sections.



124


SHAKING TABLE TEST ON CFRP CABLE DOME STRUCTURE

W. H. Qin1,2, Z. Xi1,2, Y.J. Li1, Z. C. Zhang1 and X. Zhang1 1 Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast

University, Nanjing, China, Email: [email protected] 2 National Prestress Engineering Research Center, Southeast University, Nanjing, China.

KEYWORDS :

CRFP; cable dome ; shaking table experiment; anti-seismic

ABSTRACT:

Cable dome is a kind of whole prestressed structure whose struts are in compression and the other components are

in tension. In this article, a 5.4 meter diameter cable dome model, whose cables and struts was made of CFRP bars

and CFRP pipes respectively, was fabricated and prestressed. By this way, the advantages of high-strength and

lightweight of the CFRP material was combined with advantage of the high proficiency of cable dome structure.

So that the anti-seismic performance of this kind of cable dome can be greatly improved. Shaking table experiment

of the above-mentioned model was prosecuted with multiple load cases. The time history numerical analysis on

the test model was executed and good agreement of the results can be concluded by comparing with the results of

the tested ones. Several principles about the dynamic response of this structure under the action of different seismic

waves and different maximum acceleration are drawn. Good seismic performance of CFRP cable dome structures

can be demonstrated by the research results about this paper.



125


BEHAVIOR OF GFRP WALL PANEL WITH INTERNAL TUNED LIQUID COLUMN

DAMPER

H. Wu 1, A. Chen 2 and S. Laflamme 3 1 Iowa State University. Department of Civil, Construction and Environmental Engineering, USA,

Email: [email protected]; 2 Iowa State University. Department of Civil, Construction and Environmental Engineering, USA,

Email: [email protected];

3 Iowa State University. Department of Civil, Construction and Environmental Engineering, Department of

Electrical and Computer Engineering, USA, Email: [email protected].

ABSTRACT

Pultruded Glass Fiber-Reinforced Polymer (GFRP) structures have been increasingly used in buildings and civil

infrastructure systems because of their high strength, light weight, durability, and fatigue resistance. However,

these structures are elastic and typically have low damping ratio, which limits their capability to dissipate energy

during earthquakes. Adding damping mechanisms to GFRP components can improve traditional structures’

resistance to lateral loads. This paper studies a cellular GFRP wall panel with an internal liquid flow system,

engineered to control a structure’s temperature using liquid as thermal exchange. In this study, we further adapt

the panel to allow oscillation of water in its internal hollow cells, providing supplemental damping for the GFRP

structure during seismic events. Different combinations of water heights and cell openings are evaluated using

shaking table tests to study vibration reduction of the GFRP wall panel by leveraging the motion of water. For

each combination, the natural frequency of TLCD can be predicted with a simple model. It is found that higher

water volume inside the panel can achieve greater mitigation. A Computational Fluid Dynamics (CFD) model is

created to study the liquid motion inside the GFRP panel under harmonic ground excitations. Results from the

CFD simulation are in good agreement with those from the test.





126


SPLICE CONNECTION FOR TUBULAR FRP COLUMN MEMBERS

C. Qiu 1, Y. Bai 2 1 Department of Civil Engineering, Monash University, Australia

2 Department of Civil Engineering, Monash University, Australia, Email: [email protected]

KEYWORDS

Fibre reinforced polymer (FRP), tubular member, splice connection, experimental study, axial loading, flexural

loading.

ABSTRACT

Pultruded fibre reinforced polymer (FRP) members are increasingly favoured in civil engineering as they are

lightweight and corrosion-resistant. However, their application is limited by the challenge to connect them,

especially tubular members, i.e. with closed sections. A splice connection is developed in this paper for tubular

FRP members and its mechanical performance under axial and flexural loadings is investigated. The developed

splice connection entails two tubular steel-FRP bonded sleeve joints (BSJs) and a steel bolted flange joint (BFJ)

in between. Experimental tests were conducted on the splice connections of varied bond lengths and bolt

configurations; results are reported and discussed regarding failure mode, load-displacement behaviour and strain

response. The experimental investigation revealed that an effective bond length exists for the BSJs under axial

loading, and that an eight-bolt configuration for the BFJ is more effective compared to a four-bolt one in terms of

tensile and rotational stiffness and strength. Besides, it is concluded that the splice connection can be designed to

fail in a ductile manner under both axial and flexural loadings.




127


BRIDGE PARADIS NORWAY: DESIGN AND ENGINEERING OF A 42M SPAN

FULL FRP FOOTBRIDGE

Liesbeth Tromp1, Kees van IJselmuijden 2, Stian Persson 3 1 [email protected], Royal HaskoningDHV, Infrastructure, Rotterdam, The Netherlands;

2 Royal HaskoningDHV, Infrastructure, Amsterdam, The Netherlands; 3 Norwegian Public Roads

Administration-Statens vegvesen, Bridge Department Region West, Bergen, Norway;

KEYWORDS :

All FRP and smart FRP structures; Case studies ; Codes, standards and design guidelines; Durability, long-term

performance

Mini-Symposium: "Full FRP system: design and standard"

ABSTRACT:

This paper presents the engineering story behind the bridge Paradis, Bergen, Norway. It is a full Fiber Reinforced

Polymer (FRP) tender design, prepared by Royal HaskongDHV. The material and detailing have been optimised

for the application in the Norwegian wet and cold climate. Statens vegvesen requires a low maintenance solution

to minimise life cycle costs and hindrance for traffic on road and rail. The choice for FRP was made to prevent

durability issues due to thermal fatigue and salting in winter times.

With its free span of 42m, this bridge is one of the longest spans for bridges in full FRP worldwide. A team of

architects and engineers of RoyalHaskoningDHV prepared the design in close cooperation with a multi

disciplinary team of the Client, Statens vegvesen. This way of work contributed to the confidence in FRP design

and developing design and engineering protocols for FRP structures in Norway. In the design use was made of the

latest insights in FRP design, safety concepts and material safety factors. Structural challenges involved

connections, stability of FRP members and behaviour of FRP material and connections under sustained loading.

This paper presents the interaction of design, material and manufacturing process from an engineering perspective.

It describes the results of the structural analysis and highlights the principle of the solutions for reliable and easy

to assemble connections.

Figure 3. Bridge Paradis, Bergen, Norway



128


EFFECTS OF HOLE GEOMETRY AND BOLT TIGHTENING ON CREEP

BEHAVIOR OF PIN-BEARING PULTRUDED FRP CONNECTIONS

Dr. David W. Scott1 and Javaid Anwar2 1 Georgia Institute of Technology, School of Civil and Environmental Engineering, Atlanta, GA, USA; 2

National University of Sciences and Technology, School of Civil Engineering, Risalpur, Pakistan


KEYWORDS :

All FRP and smart FRP structures; Creep; Durability, long-term performance; Codes, standards and design

guidelines; Pultrusion; Connections

ABSTRACT:

This paper presents the results of an experimental investigation into the time-dependent pin-bearing behavior of

pultruded E-glass/polyester fiber-reinforced polymer (FRP) composite materials. In this study, long-term pin-

bearing strength tests are carried out on single-bolt connections subjected to in-plane loading in tension under a

double-lap shear configuration. The connection geometry is selected such that bearing is the predominant failure

mode. The time-dependent response of the connection is evaluated at various load levels and lateral applied bolt

torques. The time-dependent experiments are carried out for durations of up to 1,000 hours at sustained load levels

of 60% and 90% of the characteristic short-term pin-bearing strength. The results indicate that increasing loads

and lateral applied torque significantly increase bolt-hole deformations in the system. In addition, apparent

increases in short-term pin-bearing strength due to lateral applied torque are lost when the FRP material exhibits

viscoelastic behavior under sustained loading.



129


ELASTIC GRIDSHELL IN COMPOSITE MATERIALS: SOME RECENT

DEVELOPMENTS

Jean-François Caron1, Olivier Baverel1, Lionel du Peloux1, Cyril Douthe1 1 Navier Laboratory, Université Paris-Est, ENPC/IFSTTAR/CNRS

Ecole des Ponts ParisTech, 6-8 Ave Blaise Pascal

77455 France

[email protected]

KEYWORDS :

All FRP and smart FRP structures; Structure ; FRC and cement composite materials; Characterization of FRP


ABSTRACT:

This article shows how composite materials might be an original and profitable solution for lightweight structures

called gridshells. In this paper the principal characteristics of gridshells are recalled first and a demonstration that

glass fibres reinforced polymers (GFRP) are suitable for these structures is shown.

The purpose of the proposed article focuses on the last realization in France, a temporary church in Creteil near

Paris, and on some other developments, including a mixed solution with concrete, theoretical developments and

an original green urban application.

Ephemeral Cathedral of Créteil (figure 1-a) was build in 2013, always in place, and cover 300m2. It represents the

only composite gridshell in the world, and the most accomplished. It was used “for real” during the refection of

the original cathedral, and is now for city’s association meetings. The subjects of numerical simulation,

construction, details, reliability and robustness are addressed in the paper. A point is made on the actual situation

and durability, and the potential of a new theoretical development about the nonlinear behavior of this kind of

deployable structures is described briefly.

A new attempt is made, replacing the GFRP bracing of the structure, and the classical canvas for roofing, by a

more fleshy solution. A thin layer of High Performance Concrete is lay on the final shape, quite deformable at this

stage, stiffening the structure as a classical bracing. The thin grid on which the cement is laid, is a fabric fasted on

the flat structural grid, and deployed in the same time. Details for the fabrication of a 2mx2m prototype are given,

and mechanical testing are described. It provides a way to imagine more usable gridshells, with a better thermal

or acoustic behavior for instance, and always affordable from both economical and environmental point of view.

Finally, another application (figure 1-b) of gridshells for the vegetalization of urban area, for fighting the heat

island phenomenon and helping biodiversity is proposed.

Figure 1 : a- Ephemeral cathedral of Créteil, b- vegetalized gridshell



130


FALCON – A MULTI-DISCIPLINARY EFFORT TO PROMOTE FRP BRIDGES IN

SWEDEN

Reza Haghani 1, Erik Olsson1,2 1 Chalmers University of Technology, Department of Civil and Environmental Engineering, Gothenburg,

Sweden; 2ELU Consultants, Gothenburg, Sweden (corresponding author: [email protected])

KEYWORDS :

All FRP and smart FRP structures; Structure ; Codes, standards and design guidelines;

Mini-Symposium: “FRP Bridges”

ABSTRACT:

Sweden has a long history in using fiber reinforced polymer (FRP) composites in marine, transportation and energy

sectors. However, when it comes to application of composite materials to build bridge structures, it somewhat falls

behind.

Despite several advantages that FRP composites offer, such as high specific strength and stiffness, corrosion

resistance and light-weight, their infrastructural applications in Sweden have not been fully understood and yet to

be realized. The first efforts to use FRP composites for construction of pedestrian bridges started in 2011, however,

due to lack of knowledge about the materials and design of composite structures among engineers, they were

halted.

Falcon, a joint effort project with total budget of 640 k Euro funded by VINNOVA and co-funded by industrial

consortium partners, aims at gathering together the relevant parties, consisting universities, research institutes,

bridge designers, composite manufacturers and clients to realize the first FRP bridge in Sweden. The main

objectives of the project are to investigate and implement the best practice for FRP bridges and improve the

procurement processes for bridge owners and thereby pave the way towards widespread infrastructural application

of composites. This paper, presents some results of this project including legal hindrances and possible strategies

to promote FRP as a construction material for future bridges.



131


TOWARDS A STRUCTURAL EUROCODE FOR FRP STRUCTURES: THE ROLE

OF CEN/TC 250

L. Ascione 1

1 Dept. of Civil Engineering, University of Salerno, Italy, Email: [email protected]

KEYWORDS

Full composite structures, Design rules, Standardization

ABSTRACT

Over the past twenty years, several innovative solutions have confirmed the usefulness of composite structures

made of FRPs (Fibre Reinforced Polymer or Plastics), both within and outside Europe. The use of FRP profiles,

shell structures and sandwich structures is particularly advantageous for applications in the Civil Engineering

field. FRP bearing structures are therefore widely used for the construction of buildings for industrial or residential

purposes. FRP usage has also become increasingly widespread for civil engineering works. Applications range

from lock gates, to entire bridges or bridge decks both for pedestrian and vehicular traffic. Due to their steadily

increasing market volume and given the complexity of selection from available materials for FRP structures, it

became obvious that it would be necessary to develop a standardization document for both the production of FRP

structural elements and practical rules for the design and verification of structures to be used for buildings and

civil engineering works. CEN Technical Committee 250 (CEN/TC250) has taken the initiative to prepare a

document addressing the purpose and justification for new European technical rules and associated standards for

the design and verification of composite structures made of FRPs. CEN/TC250 formed a Working Group, WG4,

to develop the work item. The convenor is the author of this paper. The work item is motivated by the need to

both ensure adequate reliability of the applications, as well as promote a broader market for these materials and

ensure a circulation of these materials between EU countries conforming to well-defined standards. The aim of

this paper is to summarize and diffuse the activity already developed by CEN/TC 250, as well as highlight the

further procedures to be followed on the road towards the publication of a structural Eurocode dedicated to FRP

structures.



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132


RC structures internally reinforced by FRP bars


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133


IMPROVEMENT OF MECHANICAL SHEAR RESISTANCE OF HIGH MODULUS

CFRP ROD WITH GFRP RIBS

Hiroaki Hasegawa 1, Nobuhiro Hisabe 1, Yoshiki Onari 2 and Isamu Yoshitake 2 1 Mitsubishi Chemical Infratec Co.,Ltd., Tokyo, Japan

2 Yamaguchi University, Department of Civil and Environmental Engineering, Ube, Yamaguchi, Japan

Email: [email protected] (Isamu Yoshitake)

KEYWORDS

Strengthening, Bond strength, Interfacial stresses, CFRP rod internal reinforcement, Cantilevered slab, NSM.

ABSTRACT

This study focuses on the strengthening method for upper-side of cantilevered bridge deck slabs subjected to

negative bending moment. A general strengthening method in Japan, RC overlay method, is to place reinforcing

bars and concrete on existing deck slabs. For prevention of reinforcement corrosion, thick concrete cover (100 mm

or thicker) is required in the method. Such system induces the increase of dead load, and it may negatively

influence on bridge girders and substructures. Near-surface-mounted (NSM) method using FRP rods/strips can

decrease the thickness of strengthening layer compared to the RC overlay method. In particular, NSM using CFRP

rod/strip of high modulus has several advantages, such as high strengthening-effect and low deformation. The high

modulus CFRP rod/strip are manufactured by PULTRUSION method, so the surface of the composite materials

is smooth without ribs like rebars. Hence, the most concern of the reinforcing material is low bond performance.

In this study, GFRP ribs were attached to CFRP rods to improve the bond strength (Figure 1). The study prepared

various CFRP ribs and conducted fundamental tests. Pull-out test of the CFRP rod having GFRP ribs was

conducted to examine the bond performance (Figure 2). Flexural loading test using RC beam embedding these

CFRP rods was carried out to confirm the strengthening effect (Figure 2). The pull-out test confirmed that even

CFRP rod attached with GFRP ribs of 3.0 mm thick indicated adequate bond strength. The experimental

investigation confirmed that by providing a rib of over 3.0 mm thick, the same degree of bonding strength as the

reinforcing bars can be obtained and the load-bearing capacity of the strengthened beams were higher than the

designed load.

Figure 1: CFRP rod with GFRP rib



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(a) Pull-off test (b) Flexural loading test

Figure 2: Test methods of bond-improved CFRP rods

30

L=

50

t

30

50

Mortar

Dia=55

Gypsum plaster

Steel plate

10

16

0

GFRP rib

11

05

0

Unbonded section

Thickness of GFRP ribt = 3.0, 4.5, 6.0 mm

1015

0

10

Interval of GFRP

3@200=60050

10050

125

CFRP rod (HM8)

Side ViewSectional View

Mo

rtar

16

0

100 1650 100

1850

100 700 250 700 100Interval of stirrup

7@100=700 125

Rebar : D6

Stirrup : D10

16

0

250

11

05

0

50150

50

10



135


SERVICEABILITY AND MOMENT REDISTRIBUTION OF CONTINUOUS

CONCRETE ELEMENTS REINFORCED WITH STEEL-BASALT BARS

Mohammad Akiel1, Tamer El-Maaddawy2, Ahmed El Refai3

1 McGill University, Department of Civil Engineering and Applied Mechanics, Montreal, Canada; 2 UAE

University, Department of Civil and Environmental Engineering, Al Ain, UAE (corresponding author:

[email protected]); 3 Laval University, Department of Civil and Water Engineering, Quebec City,

Canada

KEYWORDS:

Hybrid structures; Experimental study ; FRP internal reinforcement; Codes, standards and design guidelines

ABSTRACT:

The serviceability and moment redistribution of continuous concrete flexural elements internally-reinforced with

either basalt fiber-reinforced polymer (BFRP) bars or a combination of steel and BFRP bars are evaluated in this

paper. Six two-span concrete specimens were constructed and tested. The specimens were 200 mm deep, 500 mm

wide, and 5000 mm long. Each span had a length of 2400 mm. Three specimens were reinforced with BFRP bars

only whereas the remaining three specimens were reinforced with hybrid steel-BFRP bars. The specimens had

different hogging-to-sagging reinforcement ratios. Specimens reinforced with hybrid steel-BFRP bars were

designed in a way to have nominal sagging and hogging moment capacities similar to those of their counterparts

reinforced with BFRP bars only. The use of hybrid steel-BFRP reinforcing bars rather than BFRP bars only

improved the serviceability performance of continuous concrete elements without compromising their

deformational capacity. Specimens reinforced with hybrid steel-BFRP bars exhibited less deflections and smaller

crack widths at service load than those of their counterparts reinforced with BFRP bars only. Hybrid-reinforced

specimens reached their ultimate loads at deflection values comparable to those of their counterparts reinforced

with BFRP bars only. The behavior of the specimens reinforced with BFRP bars only deviated from the elastic

response, which resulted in a considerable moment redistribution between the sagging and hogging regions.

Specimens reinforced with hybrid steel-BFRP bars exhibited less deviation from the elastic response and lower

moment redistribution ratios comparted with those of their counterparts reinforced with BFRP bars only. Figure 1

shows a typical specimen at failure.

Figure 1: A test in progress



136


NUMERICAL MODELING OF THE INTERACTION BETWEEN GFRP REIN-

FORCEMENT AND HIGH STRENGTH CONCRETE DURING HYDRATION

PROCESS

Slim Kammoun1,2, Ahlem Sdiri1 and Atef Daoud1,3

1Université de Tunis El Manar, National Engineering School of Tunis, Civil Engineering Laboratory, Tunisia,

Email: [email protected]; 2 Université de Gabès, National Engineering School of Gabès, Tunisia; 3

Université de Sfax, National Engineering School of Sfax, Tunisia.

KEYWORDS :

Fields applications and case studies; Modeling ; Bond and interfacial stresses; Durability, long-term performance

ABSTRACT:

Numerical study has been conducted to simulate the behavior of the early-age high strength concrete (HSC)

reinforced with Glass Fiber Reinforced Polymer (GFRP) rebars. During hydration, HSC is subjected to both

thermal and autogenous deformations. Once restrained, these deformations might entail early-age cracking. To

model this early-age behavior, a numerical chemo-thermo-mechanical scheme has been developed and

implemented in ABAQUS finite element software via various user subroutines. Neither basic nor drying strains

are accounted for in this paper. To account for damage in HSC, the well known Mazars's elastic-damageable model

is adopted. Within this model, Young's modulus, Poisson's coefficient and damage parameters are assumed to

evolve depending on the hydration degree. Mazars's constitutive law is implemented via UMAT subroutine. GFRP

rebars are considered to be elastic and transversally isotropic. Interface between GFRP rebars and HSC is assumed

to be perfect. In a first attempt, an extensive validation of the concrete model is performed against experimental

data from literature. They are selected for both plain and steel reinforced early-age HSC, with various thermal and

mechanical boundary conditions. In a second attempt, steel rebars are substituted by GFRP ones while keeping the

same reinforcement percentages and configurations. Numerical predictions of GFRP reinforcement are compared

against those of steel reinforcement.

Figure 1 : Damage contours at 140h in cross sections and longitudinal cuts for two reinforcement

configurations: 1Φ12 and 4Φ6. (a) Steel rebars (b) GFRP rebars.




137


PARAMETRIC STUDY ON BOND OF GFRP BARS IN ALKALI ACTIVATED

CEMENT CONCRETE

Biruk H. Tekle1, Amar Khennane 2, Obada Kayali 3

1,2,3 School of Engineering and Information Technology, UNSW Canberra, Campbell, Australia;


KEYWORDS:

Alkali Activated Cement Concrete; GFRP bars ; Bond properties; Parametric study

ABSTRACT:

Bond behaviour plays an important role in the design and performance of reinforced concrete structures. In this

study, a finite element model is developed for beam-end specimens. The bond between the GFRP bar and Alkali

Activated Cement (AAC) concrete is modelled by surface-based cohesive behaviour. The GFRP bar and the

concrete are modelled using 8-node linear brick element. The shear and flexural reinforcements are modelled as a

two-node linear three-dimensional truss element. The accuracy of the model is validated by comparing different

model predictions with experimental results from the literature. Figure 1 and Figure 2 shows this comparison

between an experimental specimen and the model in terms of failure mode and free end and loaded end bond

stress-slip curves, respectively. The verified model is then used for analysing the effect of different parameters

such as: concrete cover, bar diameter, concrete compressive strength, lead length (unbonded length at loaded end),

embedment length and elastic modulus of GFRP bars on bond behaviour. Each of this parameter is varied on a

range of applicable values as shown in Table 1 in order to study its influence on the bond behaviour between GFRP

bars and AAC concrete. The parametric study showed that the bond behaviour is mainly affected by concrete

cover, bar diameter, embedment length and compressive strength of the concrete. The effect of GFRP bar elastic

modulus is not as pronounced as that of the other parameters, while the influence of lead length can be avoided by

providing enough unbonded length at the loaded end. The parametric study is further used to calibrate a well-

known bond equation and develop a new regression equation for predicting the maximum bond stress. The

predicted results from these equations showed a good agreement with the experimental as well as finite element

results with a ratio close to one as can be observed in Figure 3.

Figure 1 : Experimental vs model failure mode: (a) A16-6d1 experiment; (b) A16-6d model


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Figure 2 : Experimental vs modelling bond stress-slip curves for A16-6d

Table 1 : List of parameters and corresponding range of variation

Parameter Range of variation Model ID

Clear concrete cover As a multiple of bar diameter (⌀16 mm):

from 1d to 5d at 1d increment

Cover_1d to Cover_5d

Bar diameter Standard GFRP bar diameters: 9.5,

12.7, 19.05, 22.2 and 25.4 mm

Diam_10, Diam_13, Diam_19,

Diam_22 and Diam_25

Concrete compressive

strength

20 MPa to 80 MPa at 10 MPa increment Comp_20 to Comp_80

Lead length 25 mm, 75 mm, 100 mm, 150 mm and

200 mm

Lead_25, Lead_75, Lead_100,

Lead_150 and Lead_200

Elastic modulus of

GFRP bar

42 GPa and 50 GPa Modulus_42 and Modulus_50

Embedment length From 3.0d to 12.0d at 1.5d interval Embed_3d to Embed_12d

Figure 3 : Predicted to test (FEA model) bond stress ratios versus embedment length



139


BOND STRENGTH OF POST-INSTALLED GFRP IN BEAM-COLUMN

CONNECTIONS

Muhammad S. Bajwa1, 3, Benjamin Z. Dymond1, Rania Al-Hammoud2

1 University of Minnesota Duluth, Department of Civil Engineering, Duluth, Minnesota, USA; 2

University of Waterloo, Department of Civil and Environmental Engineering, Waterloo, Ontario, Canada; 3

([email protected])

KEYWORDS:

Strengthening and repair; Bond Behaviour

ABSTRACT :

Post-installed reinforcement in concrete is used to connect a new concrete member to an existing concrete

structure. Design using post-installed reinforcing bars is gaining acceptance due to design flexibility, formwork

simplification and the ability to have horizontal, vertical, and overhead applications. Research has been conducted

on the efficacy of post-installed steel reinforcement in concrete structures. However, steel corrodes in aggressive

environments resulting in a loss of bond strength and serviceability. Alternatively, glass fiber-reinforced polymer

(GFRP) bars can be used as post- installed reinforcement. GFRP bars are gaining acceptance in the structural field

due to their corrosion resistance and high strength to weight ratio. This research presents an experimental study

with GFRP bars from three manufacturers, which were post-installed using an epoxy-based adhesive. Eight

specimens were constructed and tested monotonically to failure. A specimen was composed of two identical

vertical elements, which were anchored into the base of the structure using post-installed GFRP bars. The

specimens were designed to simulate a rigid connection of two cantilever beams to a column. The concrete

compressive strength for all the specimens was 3 ksi (20.68 MPa) and the size of all the post-installed and cast-in-

place bars was #4 (#13). The specimens were tested with bars installed at 6 and 11.5 in. embedment depths (15.24

and 29.21 cm). The results from the specimens with bars installed at a longer embedment depth indicated an

increase in the loading capacity and the ductility compared to the specimens with bars installed at a shorter

embedment depth. The evaluation of bond strength was done by comparing the type of failure and load capacity

of the post-installed GFRP bars with the cast-in-place steel and GFRP bars. The specimens with cast-in GFRP bars

exhibited a bond-slip failure, whereas the specimens with post-installed GFRP bars had a splitting failure (concrete

cone breakout), indicating a stronger bond of the post-installed GFRP bars with concrete.



140


EXPERIMENTAL INVESTIGATION OF GEOPOLYMER CONCRETE BEAMS WITH

RECTANGULAR GFRP SPIRAL REINFORCEMENT

Ginghis B. Maranan 1, Allan C. Manalo 2, Tanniru Wamshi Krishna 2, Brahim Benmokrane 3

1 School of Engineering, The University of Waikato, Hamilton, New Zealand; 2 School of Civil Engineering and

Surveying, University of Southern Queensland, Toowoomba City, Australia; 3 Department of Civil Engineering,

University of Sherbrooke, Quebec, Canada (Ginghis Maranan: [email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; FRP internal reinforcement;

Codes, standards and design guidelines; GFRP spirals ; geopolymer concrete beams

ABSTRACT:

The combination of glass-fibre-reinforced polymer (GFRP) rebars and geopolymer concrete is an innovative

construction technique for the development of civil infrastructures with high durability and high sustainability and

with adequate strength and structural integrity. However, few studies have dealt with this system particularly on

the use of GFRP spirals as shear reinforcement for geopolymer concrete beams. In this study, the shear behaviour

of geopolymer concrete beams transversely reinforced with continuous rectangular GFRP spirals (Figure 1) was

investigated using the four-point static bending test. Five full-scale beams were designed, prepared, and tested up

to failure: one control beam without transverse reinforcement, three spirally-reinforced beams with varying spiral

pitch (i.e. 75 mm, 100 mm, and 150 mm), and one beam with conventional GFRP stirrups spaced at 100 mm on-

centres. As can be expected, the shear performance of the beam increases as the spiral pitch decreases because the

closely spaced spirals enhanced both the shear strength contribution of the confined concrete core and the

longitudinal reinforcement dowel action, effectively controlled the widening of shear cracks, and distributed the

pressure uniformly along the shear span. The shear load-bearing and deflection capacities of the control beam were

63 kN and 12.7 mm, respectively. With the use of GFRP spirals, the shear strength and deflection capacity

increased by as much as 220% and 410%, respectively. The shear strength and deflection capacity of the spirally-

reinforced beam were 19 % and 116 % higher than that of the conventionally-reinforced beam, respectively. It can

be deduced, therefore, that the GFRP spiral is a viable alternative to the traditional closed GFRP stirrups because,

aside from improving the beams’ overall performance, it can also reduce the material expenditures and the time

and cost of installation.

Figure 1 : Continuous rectangular GFRP spirals

mailto:[email protected].



141


BEHAVIOR OF CONCRETE DEEP BEAMS REINFORCED WITH GFRP HEADED

END BARS

Ahmed Mohamed1, Ehab El-Salakawy2

1,2 University of Manitoba, Civil Engineering Department, Winnipeg, Canada


KEYWORDS

Deep beams, glass fiber-reinforced polymers, headed end bars, shear span-to-depth ratio, shear strength.

ABSTRACT:

Reinforced concrete (RC) deep beams are commonly used as transfer girders in high rise buildings and bridges, as

they have the capability to sustain higher loads compared to slender beams. Deep beams are characterized by their

relatively small shear span-to-depth ratio. The use of fibre-reinforced polymer (FRP) bars, as an alternative to steel

bars, is a promising solution to mitigate the deleterious effect of steel corrosion. In particular, glass (G) FRP

reinforcement becomes more attractive to the construction industry because of its lower cost and more deformation

before failure. However, due to the relatively low modulus of elasticity of GFRP with respect to steel, GFRP-RC

deep beams will be susceptible to deeper and wider cracks, which will in turn adversely affect the shear capacity.

Also, FRP has a different bar surface and bond characteristics than that of steel, which require a longer

development length. In addition, very little experimental data exist for FRP-RC deep beams. This paper presents

an experimental study designed to demonstrate the shear behaviour of concrete deep beams internally reinforced

with GFRP and without web reinforcement. In this study, three large-scale simply supported RC deep beams

reinforced with headed-end GFRP bars were constructed and tested up to failure under monotonic load using three-

point loading scheme. The specimens have a rectangular-section of 590-mm height by 250 mm width, while the

length of the specimens are 2100, 2600, and 3100 mm. The main variable is shear span-to-depth ratio, which varied

between 1.0, 1.5 and 2.0. The test results are presented in terms of ultimate strength, cracking, deflection and

strains in reinforcement. The test results confirmed the formation of the strut-and-tie model. Also, it showed that

increasing the shear span-to-depth ratio led to decreasing the load capacity of the beam significantly.

Table 1: Details of Testing Specimens

Beam ID Depth

(mm)

a*

(mm)

fc’

(MPa) a/d **

Reinforcement ratio

ρ%

SDB1.0 508.6 520 43 1.0 1.0

SDB1.5 508.6 770 46 1.5 1.0

SDB2.0 508.6 1020 45 2.0 1.0

* a is the clear shear span

** d is the effective depth

PI gaugesLVDTs

MTS Machine

200.00

150.00 280.00

a a

All Dimensions are in mm

150.00280.00

Figure 1: Beams Test Set-up



142


INFLUENCE OF DIFFERENT APPROACHES ON DESIGN, DESIGN VALUES AND

GENERAL SAFETY FOR INTERNAL FRP REINFORCEMENT

André Weber1, Faustin Gaufillet,2

1 Schoeck Bauteile GmbH, R&D, Baden-Baden Germany; 2 Schoeck SARL, Entzheim, France


KEYWORDS

Fields applications and case studies; Material ; Codes, standards and design guidelines; FRP internal

reinforcement Standards , Design concept

ABSTRACT:

Since more than 20 years there is a growing interest in internal FRP reinforcement. In this time a couple of

interesting applications have been developed. It is interesting, that in different regions different applications are in

the focus. While in Northern America corrosion applications like bridge decks and barriers are the field of attention

in Europe there are temporary and electrical non-conductive applications are in the main focus. For these different

application groups different design and verification approachs had been followed.

For structures like diaphragm walls, where we have overlap between steel and FRP we need to follow the same

design approach for steel as for FRP reinforced parts of the structure. This starts for the partial factors for actions

as well as them for different materials.

The question of under-reinforced structures with internal FRP reinforcement has to be posed. In contrast to over-

reinforced structures the under-reinforced structure shows much more deformability, but the resistance of the FRP

has to be predicted correctly, How the different failure mode has to be taken into account?

How the resistance of FRP is determined. The same bar has different resistance in different regions.

Is there a clear definition of short term loading: Is this 1h, 10h, 100h, 1 year or 10years. From which loading time

live load has to be taken into account as sustained load?

Another question is the size/diameter of reinforcement. While engineers design with required reinforcement areas

and can distribute a different number of bars into a structure, some Standards fix local historical sizes known from

the steel industry for FRP.

Assuming the physics as well as materials are the same all over the world it seems to be strange, that we have so

different design results for FRP reinforced structures, while steel reinforced structures seem to be much more

similar

This paper analyses the different design approaches using practical examples from 20 years of experience in this

field.


Composites


143


Figure 1 : Strains in concrete and steel vs. GFRP reinforcement for the same sectional area

In figure 1 is to be seen that higher stress in the concrete is the consequence of high strain reinforcing materials.

High strain is observed for high strength and/or low modulus reinforcement like GFRP-reinforcement. In over-

reinforced sections the lower stiffness leads directly to lower capacity of this section regardless of the possibly

higher strength of this reinforcing material.



144


CONTRIBUTION OF SHEAR TRANSFER MECHANISMS AND STRENGTH OF

GFRP REINFORCED CONCRETE

Danielle Pacheco 1, Daniel Cardoso 1, Martin Noël 2 1 Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Department of Civil Engineering, Rio de Janeiro,

Brazil; 2 University of Ottawa, Department of Civil Engineering, Ottawa, Canada; (corresponding author:

[email protected])

KEYWORDS :

Choose an element ...; Experimental study ; Choose an element ...; Choose an element ...; GFRP reinforced

concrete; Shear transfer mechanisms; Shear strength; Digital image correlation;

ABSTRACT:

This paper aims to discuss the shear behavior and strength of concrete beams internally reinforced with glass-fiber

reinforced polymer (GFRP) longitudinal bars, with and without stirrups. The partial results of an ongoing

experimental program intending to investigate the crack kinematics and contribution of different shear transfer

mechanisms to the final strength are presented. The test results for two dowel specimens and six beams subjected

to four-point bending are reported. Digital image correlation (DIC) was used to gather information about crack

opening and sliding throughout the tests and the measured kinematics were used as inputs in theoretical models.

The approach was validated with the experimental results and was used to quantify the participation of each shear

mechanism. It is shown that the contribution of aggregate interlock gradually reduces as the crack opens, whereas

participation of stirrups linearly increases up to failure.



145


A REVIEW ON EXPERIMENTAL DEFLECTIONS IN FRP RC FLEXURAL

MEMBERS

Cristina Barris1, Arnau Bover1, Javier Gómez1, Lluís Torres1

1 AMADE, University of Girona, Girona, Spain ([email protected])

KEYWORDS :

Experimental study ; FRP internal reinforcement; Codes, standards and design guidelines

ABSTRACT:

It is commonly acknowledged that serviceability limit states may govern the design of concrete structures

reinforced with fibre reinforced polymer (FRP) bars, mainly due to the lower modulus of elasticity of FRPs

compared to that of steel. FRP bars present a wide range of rebar surfaces that can have an effect on the

deformational behaviour of FRP reinforced concrete (RC) flexural members. In the last three decades, many

experimental studies providing results on deflections of FRP RC beams have appeared, and several approaches for

adjusting expressions initially developed for steel RC beams have been published.

This paper aims at studying the experimental deflection of FRP RC beams, by analysing the results available in

the literature of 171 beam specimens tested under 4-point bending load. The theoretical deflection is calculated

according to an equivalent moment of inertia based on interpolation of deflection, and it is compared to the

experimental value. A deflection ratio (DR) is defined as the predicted/experimental deflection. The influence of

the level of loading, the surface coating and the main parameters affecting the tension stiffening effect (nρ and d/h

ratio) is analysed and conclusions are drawn. It is observed that DR increases with the load level. Moment ratios

close to the cracking moment provide higher scatter of results, whilst high moment ratios give DR lower than the

unity. Specimens reinforced with sand coated FRP yield to marginally lower values of DR compared to wrapped

or ribbed coating. Finally, the effect of nρ or d/h ratio on DR was not clearly observed in this work due to the

scatter of results found in the analysis.

Figure 1: Experimental vs. theoretical deflection at M=1.5·Mcr and M=3.0·Mcr.




146


NUMERICAL SIMULATION OF SHEAR FAILURE IN SCALED GFRP

REINFORCED CONCRETE BEAMS WITHOUT STIRRUPS

S. Khodaie 1 and F. Matta 2 1 University of South Carolina, Dept. of Civil and Environmental Engineering, USA

2 University of South Carolina, Dept. of Civil and Environmental Engineering, USA, Email: [email protected]

ABSTRACT

Evidence from load tests on concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars without

stirrups highlights a decrease in the shear stress at failure at increasing effective depths. The physical explanation

of this size effect remains controversial, and existing nominal shear strength algorithms may not consistently

capture this phenomenon. This paper reports on the validation of a computational model based on a concrete

Lattice Discrete Particle Model (LDPM) vis-à-vis actual four-point bending test data for slender GFRP RC beams

having an effective depth in the range 292-883 mm. The concrete LDPM approximates the physical heterogeneity

of concrete, and incorporates constitutive laws that are important to simulate shear transfer mechanisms. The

numerical simulations yielded accurate predictions of load-deflection response, strength, and diagonal-tension

failure mode. These preliminary results are relevant since, for the first time, they demonstrate the successful use

of numerical simulations to accurately predict the shear behavior of scaled GFRP RC beams without stirrups,

whereas existing nominal strength algorithms may not consistently yield accurate predictions.



147


EFFECT OF HIGH TEMPERATURES ON THE BOND PERFORMANCE OF GFRP

BARS TO CONCRETE

Inês C. Rosa1, João P. Firmo1,2, Luís Granadeiro1, João R. Correia 1

1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; 2 Corresponding author:

[email protected]

KEYWORDS:

Experimental study; Temperature; FRP internal reinforcement; Bond and interfacial stresses

ABSTRACT:

Glass fibre reinforced polymer (GFRP) bars have been successfully used during the last decade to reinforce

concrete structures subjected to aggressive environments, especially due to their corrosion resistance and

increasingly competitive costs when compared to stainless steel reinforcement. However, it is well known that the

strength, stiffness and bond properties of GFRP rebars are severely reduced with increasing temperatures,

particularly when approaching the glass transition temperature (Tg) of the polymer matrix (typically in the range

of 65-150 ºC). This paper presents results of an experimental investigation on the bond between concrete and sand-

coated GFRP bars at moderately elevated temperatures. Pull-out tests on GFRP bars embedded in concrete

cylinders were performed up to 140 ºC; in these tests two bond lengths of the GFRP bars were considered,

corresponding to 5 and 9 times the diameter of the rebars. Specimens were first heated up to the predefined

temperature (20, 40, 60, 80, 100 or 140 ºC) and then loaded up to failure. The applied load and the slip of the bars

at both loaded and free ends were measured; the results obtained confirmed that the stiffness and strength of the

GFRP-concrete interface suffers significant reductions with temperature, especially when the Tg of the GFRP

rebars is approached. Bond vs. slip relations of the GFRP-concrete interface are proposed for each tested

temperature; these relations were derived based on a fitting procedure of the experimental data to a bond vs. slip

model available in the literature for FRP bars in concrete, originally developed for ambient temperature.

Figure 1: Schematic view of the test setup.

Connection rod

Fixed plate

Video extensometerMetallic pipe

(loaded end)

GFRP rebar

Steel rod

Target dots

a) b)

Angled

bracket 0

5

10

15

20

25

30

0 5 10 15 20 25

Aver

ag

e b

on

d s

tres

s, τ

[MP

a]

Loaded end slip, s [mm]

T20-5db

T60-5db

T100-5db

T140-5db

T20-9db

T60-9db

T100-9db

T140-9db

c)

0

5

10

15

20

25

30

0 5 10 15 20 25

Aver

ag

e b

on

d s

tres

s, τ

[MP

a]

Loaded end slip, s [mm]

T20-5db

T60-5db

T100-5db

T140-5db

T20-9db

T60-9db

T100-9db

T140-9db



148


SHEAR TESTS ON GFRP REINFORCED CONCRETE BEAMS USING DIGITAL

IMAGE CORRELATION SYSTEM

M. Kaszubska 1, R. Kotynia 1, D. Szczech1, M. Urbaniak2 1 Lodz University of Technology, Faculty of Civil Engineering, Architecture and Environmental Engineering,

Łódź, Poland, Email: [email protected]; 2 Lodz University of Technology, Faculty of Mechanical

Engineering, Łódź, Poland;

KEYWORDS:

All FRP and smart FRP structures; Experimental study; FRP internal reinforcement; DIC system

ABSTRACT:

The paper presents results of experimental test carried out on T-shaped concrete beams reinforced with glass fiber

reinforced polymer (GFRP) bars without stirrups. The beams varied mainly with longitudinal reinforcement ratio

(ρl) corresponding to about: 1.0%, 1.4% and 1.8%, a number of bars, their diameter and a number of reinforcement

layers (1 or 2 layers). Beams failed due to gradual development of diagonal cracks. Beneficial influence of two

reinforcement layers was confirmed especially for the high longitudinal reinforcement ratio equal of 1.8%, while

for the low reinforcement ratio about 1.0%, no difference in the shear capacity due to number of layers was

observed. Strain and displacement measured during the test are very important parameters used in analysis of the

test results. Most researchers still use conventional techniques, e.g. strain gauges or linear displacement transducer

(LVDTs), but recently digital image correlation system (DIC) shows increasing popularity especially in the

complex stress state like shear. DIC is an innovative non-contact optical technique for the study of crack

propagation and material deformation. The paper presents comparison test results registered by LVDT and DIC

system. The main aim of the research was to investigate the shear strength and crack propagation until failure.



149


TESTS ON GFRP REINFORCED CONCRETE CLOSING JOINTS

Nader Sleiman1, Maria Anna Polak2

1 University of Waterloo, Department of Civil and Environmental Engineering, Waterloo, Canada

([email protected]);

2University of Waterloo, Department of Civil and Environmental Engineering, Waterloo, Canada

([email protected])

KEYWORDS :

All FRP and smart FRP structures; Experimental study ; FRP internal reinforcement; Frame Joints

ABSTRACT:

The use of GFRP as main reinforcement in concrete structures is an appealing option for structures in aggressive

environments. Using GFRP reinforcement in frame corner joints may be problematic considering the weak link at

the reinforcement bend; the GFRP bars are much weaker at the bent portions of the bars due to non-standardized

manufacturing processes. The behaviour of GFRP reinforced corner frame joints has not been previously studied.

In the presented research, eight full-scale GFRP reinforced knee-joint specimens were prepared and tested under

monotonic closing loads. These specimens consist of beam-column joints where the beam and column terminate

at the joint. The presented experimental program was designed to study the effect of reinforcement ratio,

confinement stirrups, and corner geometry on the behaviour of the joint.

The failure mode was altered from bar rupture to failure of diagonal strut by increasing the reinforcement ratio of

bent bars going through the joint; however this had minimal effect on ultimate strength. The addition of

confinement stirrups to the joint reinforcement resulted in a substantial increase in ultimate strength and maximum

deflection. Joints with altered geometry by including interior chamfers performed better than joints without

chamfers; their load capacity was increased marginally but the joints failed in a non-brittle matter.

Figure 4: Experimental test setup


Composites


150


EFFECT OF SURFACE TREATMENT AND TEST CONFIGURATION ON

BOND BEHAVIOUR OF GFRP REBARS

Ondrej Janus1, Frantisek Girgle2, Vojtech Kostiha2, Petr Stepánek2

1 Brno University of Technology, Faculty of Civil Engineering, Brno, Czech Republic (corresponding author:

[email protected]); 2 Brno University of Technology, Faculty of Civil Engineering, Brno, Czech Republic

KEYWORDS :

Reinforcement, Bond strength, Pull-out test, Beam test, Degradation.

ABSTRACT:

This paper deals with the determination of the effect of surface treatment and test configuration on the bond

behaviour of GFRP reinforcement embedded in concrete. Several types of tests were performed, such as centric

pull-out tests, modified pull-out tests, and beam tests to obtain the bond properties of bars with different surface

treatments. The sand-coated bars exhibited different bond behaviour compared to the ribbed ones due to different

forces transferred from the reinforcement to the concrete. This paper also focuses on the determination of the effect

of alkaline environment degradation on the efficiency of sand-coated bars. It is well-known that test configuration

affects bond behaviour, however, this effect was not sufficiently quantified until now. A modified beam-bending

test to assess the bond performance is presented in this study. The results of an experimental study comparing the

bond performance of GFRP bars with different surface treatments obtained from the beam tests and centric and

modified pull-out tests are presented.

Figure 1: Beam specimen geometry



151


PERFORMANCE STUDY OF A POST-TENSIONED CONCRETE SLAB

STRENGTHENED WITH CFRP USING 24 HR AND CYCLIC LOAD TESTING

Thanongsak Imjai 1, Surin Sutthiprapa 1 Burachat Chatveera 2 and Udomvit Chaisakulkiet 3

1 Dept. of Civil Engineering, Rajamangala University of Technology Tawan-Ok, Bangkok, Thailand; (Email:

[email protected])

2 Dept. of Civil Engineering, Thammasat University, Bangkok, Thailand;

3 Dept. of Civil Engineering, Rajamangala University of Technology Rattanakosin, Bangkok, Thailand;

KEYWORDS :

Strengthening and repair; Structural assessment ; Post-tensioned slab; EBR; Load tests

ABSTRACT:

This article presents the showcase on a performance study of post-tensioned concrete slabs using externally bonded

carbon fibre reinforced composites (CFRP). The concrete slabs are part of a full-scale 17 storey building located

in in Thailand. The original building (completed in 2000) is currently used as the residential building. Design

verifications based on ACI 318 indicated that the flexural capacity of the original post-tensioned slab was

insufficient to resist the new superimposed loads from three water tanks with capacity of 1000 litres that is planned

to install on the roof top floor. Conversely, flexural, shear and torsional capacity of the existing RC beam and

column sections were sufficient to resist the superimposed loads by up to 120% (under the roof top level). As part

of the retrofitting programme, the concrete slab was strengthened with Carbon FRP (CFRP) laminates using a

manual lay-up application. The load capacity and deflection of the FRP-strengthened slab was then re-assessed

according to the 24 hours (ACI-318) and cyclic load (ACI-437) test protocols. Based on the floor load test results,

it was found that the proposed strengthening solution was adequate to sustain the increased load demand imposed

by the water tanks.

Figure 1 : Application of EBR CFRP strengthening on post-tensioned concrete slab

Overview of the 17 stories hotel EBR strengthening



152


SHRINKAGE BEHAVIOUR OF FIBRE REINFORCED POLYMER GRID

REINFORCED INFRA-LIGHTWEIGHT CONCRETE

Yue Liu 1, Arndt Goldack 1, Mike Schlaich 1, Alex Hückler 1

1 Technische Universität Berlin, Department of Conceptual and Structural Design, Germany;

[email protected]

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; FRP internal reinforcement

ABSTRACT:

Infra-lightweight concrete (ILC) is a type of lightweight concrete (LC) with a dry density less than 800 kg/m3. ILC

has not only extremely low self-weight and excellent heat insulating capacity but also enough structural strength

for buildings. However, the shrinkage of ILC is relatively large, which may cause wide concrete cracks and steel

reinforcement corrosion. Noncorroding is the main advantage of fibre reinforced polymer (FRP) reinforcement,

which makes it suitable to substitute steel reinforcement in ILC. This paper presents the investigation on the

shrinkage of ILC reinforced with an FRP grid. Shrinkage experiments on the ILCs of different dry densities and

with different FRP grids were conducted. As expected, the shrinkage strains of FRP grid reinforced ILC prisms

are significantly smaller than that of plain ILC prisms, which allows controlling the shrinkage of ILC. Furthermore,

the CFRP (carbon fibre reinforced polymer) grid has a higher efficiency to reduce the ILC shrinkage compared

with the GFRP (glass fibre reinforced polymer) grid if the reinforcement ratios are kept the same. Moreover, the

higher the reinforcement ratio is, the greater the rate of shrinkage decline will be, if the grid materials remain

identical.

Figure 1 (a) Diagram of concrete prism (b) diagram of FRP grid



153


BOND EVALUATION OF GFRP REINFORCING BARS EMBEDDED IN

CONCRETE UNDER AGGRESSIVE ENVIRONMENTS

Alvaro Ruiz Emparanza1, Francisco De Caso Y Basalo 2, Raphael Kampmann 3 and Antonio Nanni4

1,2,4 University of Miami, Department of Civil, Architectural and Environmental Engineering, Miami (Fl) USA;

3 Florida State University, Department of Civil and Environmental Engineering, Tallahassee (Fl) USA;

(Alvaro Ruiz Emparanza: [email protected])

KEYWORDS :

Aging; Bond strength; Concrete; Composite rebars; Pullout; Seawater; Surface enhancement

ABSTRACT:

Technologies developed over the last three decades have facilitated the use of glass fiber reinforced polymer

(GFRP) composites as internal reinforcement bars (rebars) for concrete structures, which have proven to be an

alternative to traditional steel reinforcement due to significant advantages, such as magnetic transparency and,

most importantly, corrosion resistance. GFRP rebar manufacturers have developed different GFRP rebar types,

where the surface enhancement to create the bond with concrete varies. However, a knowledge gap exists related

to adequate durability of the surface enhancement in composite rebars, needed to achieve a proper bond to concrete.

Thus, the durability of the bond enhancement of GFRP rebars to concrete must be addressed. This study evaluates

the mechanical and bond to concrete properties of GFRP rebars subjected to accelerated conditioning. To this end,

specimens were expose to circulating seawater chambers, at different temperatures (23°C, 40°C and 60°C) for

different periods of time (60 and 120 days). The selected GFRP rebars were made from the same glass fibers, but

different manufacturing methods and more importantly bond enhancements: i) sand-coated with helical wrap, ii)

ribbed/external deformations and iii) external cross fibers. Bond tests after exposure were performed according to

ASTM D7913. Preliminary results show that the different surface enhancements for the same nominal size GFRP

rebars, result in different bond to concrete strength slip relationships. However, the durability for the different

types of surface enhancements for the selected GFRP rebars did not exhibit a significant change in bond to concrete

strength over the exposed period of time.



154


EXPERIMENTAL STUDY OF CONCRETE BEAMS REINFORCED WITH HYBRID

(SFCB AND BFRP) BARS

Yang Yang 1, and Gang Wu 2

1.Doctor, College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127，China;


2. Professor, Key Laboratory of Concrete and Prestressed Concrete Structures, Southeast University, Nanjing

210096, China

KEYWORDS:

Flexural behavior; Steel fiber-reinforced polymer composites bar (SFCB); Basalt fiber-reinforced polymer

(BFRP); Hybrid bars

ABSTRACT:

A combination of steel and fiber-reinforced polymer (FRP) bars can been used to afford favorable strength,

serviceability, and durability in the concrete structures. However, the traditional hybrid reinforcements (by placing

FRP bars near the outer surface of the tensile zone, and steel bars at the upper levels of the tensile zone) often lead

to the decrease of the structural design point (approaching the yielding point). In addition, the corrosion of inner

steel reinforcements may still occur after concrete cracking. In this paper, new hybrid reinforcements using steel

fiber-reinforced polymer composites bar (SFCB) and basalt fiber-reinforced polymer (BFRP) bar were proposed

and investigated. All six concrete beams reinforced with a combination of SFCB, BFRP bars, and steel bars in

different hybrid ways were conducted and tested. The result shows that: (1) The hybrid reinforcement (SFCB and

BFRP) beams can reduce the crack width and crack spacing, and also increase the ultimate capacity, compared to

the traditional hybrid reinforcement (BFRP and steel). (2) With the same the FRP/steel ratio, the SFCB beam

almost has the better performance in crack behavior and capacity compared to the traditional hybrid reinforcement

(BFRP and steel). (3) The shear failure mode was observed as the FRP/steel ratio increased.

Figure 1 : Section of specimens

10φ8@80mm

100 100700 600 700

2200

10φ8@80mm

220

30

0

S10

B49

S10B49

B49

S10B49 S12

S10

B49

B-1

B-5 B-6

B-2

B-3

B-4

S10B49

S10B85



155


BEHAVIOUR OF PRECAST SEGMENTAL CONCRETE BEAMS (PSBS)

PRESTRESSED WITH CFRP TENDONS

Thong M Pham*, Tan D Le, and Hong Hao

Center for Infrastructural Monitoring and Protection, School of Civil and Mechanical Engineering, Curtin

University, Kent Street, Bentley, WA 6102, Australia. *Corresponding author: [email protected]

KEYWORDS :

All FRP and smart FRP structures; Experimental study; Prestressing with FRP composites; Characterization of


ABSTRACT:

This paper presents a part of an ongoing research project on precast segmental concrete beam prestressed with

fibre reinforced polymer (FRP) tendons which are currently being conducted at Curtin University. Precast

segmental prestressed concrete bridge beams (PSBs) have gained rapid acceptance as they not only allow speeding

up the construction process, but also improving the quality control. Corrosion of steel tendons at joint locations,

however, causes deterioration or even collapse of the structures. This study aims at investigation of the use of

CFRP tendons in replacement of traditional prestressing steel tendons for PSBs to deal with corrosion-related

issues. Three precast segmental T-section concrete beams of 400 mm height and 3900 mm length which included

a control specimen with unbonded steel tendons were cast and tested. Both epoxied and dry shear-keyed joints

were used. Tested results indicate that CFRP tendons can be well used to replace the steel tendons on PSBs as the

beams with CFRP tendons exhibited both high strength and high ductility as compared to the beam with steel

tendons. However, the stresses in the unbonded CFRP tendons at ultimate of the tested beams were low, ranging

from only about 69% to 72% of the nominal breaking tensile strength. The type of joints greatly affects the initial

stiffness of the beams but has no effect on the opening of joints at ultimate. In addition, the codes examined in this

study predicted well the stress at the ultimate of the beam with unbonded steel tendons, however, the accuracy

significantly reduced in the case of the beams with CFRP tendons.



156


STUDIES ON DESIGN AND CONSTRUCTION MONITORING OF PRECAST

CONCRERE MUNICIPAL TUNNEL REINFORCED WITH GFRP BARS

X. Hu1, W. C. Xue1, Fei Peng1, and T. Liu1 1Tongji University, College of Civil Engineering, Shanghai China (Weichen Xue: [email protected])

KEYWORDS:

Municipal tunnel; Precast concrete, GFRP bars; Flexural capacity; Crack width; Design procedure; Construction

monitoring.

ABSTRACT: Municipal tunnel (MT) is a joint-use underground structure that houses several types of power,

water, sewerage, communications, gas, and other statutory services. Structural types of MT include cast-in-site

and precast, and precast concrete MT (PCMT) would widespread use because of cost effectiveness, high quality,

and faster construction. Corrosion of steel reinforcement in PCMT structures is one of the major challenges for

structural durability because the structures are exposed to the underground aggressive environments. Substitution

of steel bars with glass fiber reinforced plastics (GFRP) bars is an alternative solution to improve the durability of

PCMT structures. The design method of PCMT structures reinforced with GFRP bars is firstly investigated in this

paper. The improved design equation for flexural capacity of GFRP reinforced concrete members is proposed, and

that for crack width in ACI 440.1R-06 and GB 50608-2010 were summarized. Then, a PCMT structure located in

the park of 2010 Shanghai World Expo was designed according to the method presented here, and subsequently,

the structural safety of the GFRP reinforced PCMT structure is verified according to the results of construction

monitoring.



157


EXPERIMENTAL STUDY ON THE BOND BEHAVIOR BETWEEN FRP REBARS

AND CONCRETE

Arnaud Rolland1, Karim Benzarti2, Marc Quiertant3, Pierre Argoul3, Sylvain Chataigner4, Aghiad Khadour5 1 Cerema, Haubourdin, France. E-mail : [email protected];

2 Université Paris-Est, Laboratoire Navier (UMR 8205), Marne-la-Vallée, France;

3 Université Paris-Est, IFSTTAR, Département Matériaux et Structures, Marne-la-Vallée, France;

4 IFSTTAR, Département Matériaux et Structures, Bouguenais, France;

5 Université Paris-Est, IFSTTAR, Département Composants et Systèmes, Marne-la-Vallée, France;

KEYWORDS :

Composites; FRP bars; Bond; Pull-out tests; Distributed optical fiber sensors; Development length

ABSTRACT:

This study focuses on the experimental characterization of the bond behavior between concrete and Fiber

Reinforced Polymer (FRP) reinforcing bars (rebars). Pull-out tests were performed on glass, carbon, and aramid

FRP rebars, as well as on deformed steel rebars. The influence of various parameters on the bond behavior was

studied, such as the type of fibers, the diameter of the FRP bars and their surface geometry. Scanning-electron-

microscope observations were performed to study the sand coating. A main originality of the work relied on the

instrumentation of pull-out samples using distributed optical fiber sensing instrumentation (see Figure 1 (a) and

(b)) that provided access to the longitudinal strain distribution along the rebar near the rebar-concrete interface

(see Figure 1 (c)), and then made it possible to determine the effective development length of the various types of

rebars considered in this study.

Figure 1: DOFS instrumentation: (a) Geometrie of the U-groove at the surface of the rebar, (b) Pull-out

specimens instrumented with DOFS prior to concrete casting, (c) example of strain distribution along the

embedded length of a GFRP rebar measured by DOFS instrumentation during a Pull-out test

(a) (b) (c)



158


FLEXURAL BEHAVIOUR OF BFRP REINFORCED BEAMS WITH PRESTRESSED

REINFORCEMENT

Mohammad Mirshekari1, Ted Donchev1,Diana Petkova1 1 Faculty of Science, Engineering and Computing, Kingston University, London, UK

([email protected],)

KEYWORDS:

Large scale samples, RC beams, BFRP reinforcement, Prestressing, Pre-tensioning.

ABSTRACT:

Non-corrosive nature and high strength of fibre reinforced polymer (FRP) reinforcement makes it attractive for

use in concrete applications. The main problem for using FRP reinforcement is the higher deformability especially

in cases of glass and basalt FRP. One of possible approaches for reducing of the deformations is via prestressing

of the reinforcement. This research is continuation of previous investigation and presents experimental results of

six large scale concrete beams reinforced with different types of reinforcement. Five of the beams are reinforced

with Basalt FRP (BFRP) 6mm diameter bars pretensioned with differing degree of pre-stressing and one beam is

steel reinforced. The aim of the paper is to present the experimental results reflecting the behaviour of BFRP

reinforced beams with different level of prestressing and to compare them with the deformability of steel reinforced

beam. Test results showed that the prestressing of BFRP reinforced beams is resulting in reducing of their

deformability. The ultimate deflection at mid-span for BFRP beam with 40% of prestressing have 88% lower than

the steel reinforced beam at ultimate load for the steel reinforced sample.



159


EXPERIMENTAL INVESTIGATION ON FLEXURAL BEHAVIOR OF UHPC

PANELS REINFORCED WITH FRP BARS

Jiaxing Chen1, Zhi Fang 1,2

1 College of Civil Engineering, Hunan University, Changsha and China;

2 College of Civil Engineering, Hunan University, Changsha and China;

KEYWORDS:

FRP; UHPC ; Panel; Flexural capacity; Equation

ABSTRACT

The Fiber-Reinforced Polymer (FRP) has many advantages, such as high tensile strength, low self-weight and

excellent corrosion resistance, and its application has been growing to solve the problem caused by corrosion of

conventional steel reinforcement. However, the FRP bar can be seen as a type of liner-elastic material and has an

extremely low ductility, which may lead to a brittle failure of concrete structure. Moreover, the FRP has a low

Young’s modulus, reducing the flexural stiffness of concrete slab and causing the increase of the crack width. The

applications of Ultra-High Performance Concrete (UHPC) are beneficial to improve the flexure capacity and

ductility of concrete structures reinforced with FRP bars due to its high strength and compressive strain. This paper

presented the experimental results of 8 simply supported panels and studied the effect of reinforcement ratio, type

of FRP bar and gird dimension on flexural performance of UHPC panels reinforced with FRP. Experimental results

indicated that no obvious improvement of flexural capacity was obtained by increasing reinforcement ratio under

concrete crushing failure pattern. The ultimate load increased only by 14.5%, but the reinforcement ratio increased

by 39%. Failure mode show that the number of cracks increases and crack spacing decrease with reduce of gird

dimension. Based on reasonable assumptions, a predicted equation for flexural capacity of UHPC panels reinforced

with FRP bars was derived. Moreover, the results from this set of experimental tests and others literature were

compared with the predicted results. Comparison results indicate that the equation can accurately predict the

ultimate load of FRP reinforced UHPC panels.

:



160


AXIAL PERFORMANCE CAPACITY OF HOLLOW CONCRETE COLUMNS

REINFORCED WITH GFRP BARS

Omar S. AlAjarmeh1, Allan Manalo 1, Warna Karunasena1, Brahim Benmokrane2 1 Centre of Future Materials CFM, Faculty of Health, Engineering and Science, University of Southern

Toowoomba 4350, Queensland, Australia. (Corresponding author: [email protected])

2 Department of Civil Engineering, University de Sherbrook, Sherbrook, Quebec J1K 2R1, Canada.

KEYWORDS:

Hybrid structures; Experimental study ; FRP internal reinforcement; Codes, standards and design guidelines.

ABSTRACT:

Hollow concrete sections are widely used in bridge piers, electrical poles, and piles, owing to reduced material

usage and high strength-to-weight ratio. However, environmental conditions can be the main reason that affect the

performance of concrete elements reinforced with conventional steel by corrosion and rusting the internal

reinforcements. In fact, repairing and rehabilitating structural deficient elements experiencing corrosion of steel

reinforcements have cost many countries billions of dollars. To address this issue, the potential of hollow concrete

sections reinforced with non-corrosive glass fibre reinforced polymer (GFRP) bars should be explored. In this

study, four 250 mm diameter and 1000 mm high concrete columns longitudinally reinforced with 6 – 16 mm

diameter GFRP bars and 10 mm dimeter spirals spaced at 100 mm on centres were cast and tested under concentric

compressive load. The effect of the inner-to-diameter ratio on the axial strength capacity and the overall behavior

was investigated. This was achieved changing the inside hollow size from 40mm (HG40) and 65mm (HG65) to

100mm (HG100), in addition to a solid column (SG). Hollow concrete columns were tested concentrically until

failure. The results showed that the stiffness was approximately same for all concrete columns, i.e. 180 kN/mm.

However, the strength enhancement and confinement efficiency was more noticeable for columns with high than

low inner-to-outer diameter ratio especially after the post peak stage. Similarly, the ductility factor was ascending

as the inner-to-outer diameter ratio is increasing. The average contribution of GFRP bars in carrying the load was

12.2% and with the compressive strength of the GFRP bars around 51% of the tensile strength capacity at the

maximum load.



161


PERFORMANCE OF GFRP IN BALCONY SLAB THERMAL BREAKS

Sarah Boila1, David Kuhn 2, Kevin Knight 3, John Wells 4, Dagmar Svecova 1 1 University of Manitoba, Civil Engineering, Winnipeg, Canada; 2 University of Manitoba, Mechanical

Engineering, Winnipeg, Canada; 3 Red River College, Building Envelope and Technology Centre, Winnipeg,

Canada; 4 Crosier Kilgour & Partners Ltd., Winnipeg, Canada ([email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; FRP internal

reinforcement; Characterization of FRP and FRC materials/systems; Characterization of FRP reinforced thermal

break system; Thermal conductivity

ABSTRACT:

In an effort to reduce our collective consumption of natural resources and greenhouse gas emissions, the building

industry has recently focused on improving the insulation of the building envelope, thus lowering heating and

cooling loads. However, thermal bridges occurring at locations such as the interface of concrete balconies and wall

systems continue to compromise the integrity of the building envelope for the entire structure

The objective of this project is to design a practical and cost-effective thermal break system for concrete balconies

to improve the sustainability and cost efficiency of modern buildings and enhance the health, safety and comfort

of the building occupants. With a thermal conductivity approximately one tenth that of conventional reinforcing

steel, GFRP poses as an excellent solution to provide structural capacity while minimizing the thermal conductivity

across the thermal break. The performance of a GFRP reinforced thermal break will be compared to that of both

a steel and stainless steel reinforced system to demonstrate the benefits.

Representative sample sizes of the thermal breaks embedded in concrete slabs were constructed for thermal and

structural testing. Thermal testing was performed in a dual-sided thermal chamber with an interior building

temperature of +21˚C and exterior temperature of -31˚C for the Winnipeg, Canada design temperature. Thermal

sensors were embedded in the concrete slabs to record the temperature profile, allowing for determination of the

thermal conductivity of the system. These results were compared to those obtained from thermal modelling

performed in Heat 3D, allowing us to validate the accuracy of the model and fully assess the behaviour of the

system. Results are reported in industry relatable terms to ensure quick interpretation and facilitate implementation

of the system in the industry.

Figure 1 : Photograph (left) and infrared image (right) of GFRP reinforced slabs tested in thermal chambers,

taken from the warm chamber.


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162


TECHNICAL STANDARDS FOR DEBONDING IN FRP-CONCRETE SYSTEMS: AN

EXPERIMENTAL CONTRIBUTION FOR BASALT-FRP

Elisabetta Monaldo1, Francesca Nerilli1, Giuseppe Vairo2 1 Università degli studi “Niccolò Cusano”, Dipartimento di Ingegneria, Rome, Italy; 2 Università degli studi

“Tor Vergata”, Dipartimento di Ingegneria Civile e Ingegneria Informatica (DICII), Rome, Italy.

(E. Monaldo: [email protected])

Keywords: All FRP and smart FRP structures; Experimental study; Codes, standards and design

guidelines; Bond and interfacial stresses; Basalt-FRP

ABSTRACT:

Fibre-reinforced polymers (FRPs) are widely used in civil-engineering field. Their applications represent

a strengthened way for retrofitting existing concrete structures. In the context of strengthened RC beams

subjected to bending loads, a critical issue is the FRP debonding, mainly consisting in a brittle failure

mechanism. Bonding behaviour between FRP and concrete has been addressed in several

experimental, analytical and numerical studies, resulting in a number of analytical and empirical

formulations attempting to assess both maximum debonding force and effective bond length.

In this paper, analytical relationships proposed by different technical standards and guide-lines, are

consistently summarized and compared. In particular, a wide database of experimental results obtained

from debonding tests, and available in the recent literature, is reported and commented.

Finally, experimental results obtained via 42 double shear tests on basalt-based FRP (BFRP) sheets

attached on concrete supports are presented and discussed, aiming to highlight debonding mechanisms

occurring at BFRP-concrete interfaces. In this light, soundness and effectiveness of available technical

relationships, mainly proposed for FRPs based on carbon, glass and aramid fibres, are critically

discussed with reference to the case of BFRP-concrete systems. Accordingly, refinements of technical

relationships, based on a suitable calibration of model parameters and able to recover experimental

results, are proposed.



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163


GFRP STRAND PROTOTYPE: EXPERIMENTAL INVESTIGATION AND

TECHNOLOGY READINESS

Marco Rossini1, Pedro Jalles1, Gabriele Balconi2, Antonio Nanni1 1 University of Miami, Department of Civil Arch. and Environ. Engineering, Coral Gables, FL, USA.

2 Sireg Geotech, Arcore, Italy. (Marco Rossini: [email protected])

Keywords: New composite materials, systems and strengthening techniques; Experimental

study; Characterization of FRP and FRC materials/systems; Prestressing with FRP

composites; GFRP strands;

ABSTRACT:

Employment of corrosion-resistant reinforcement represents a widely-recognized effective strategy to

ensure long-term durability of Reinforced Concrete (RC) and prestressed concrete (PC) structures.

Fiber-Reinforced Polymer (FRP) composites are a reliable non-metallic solution, able to ensure both the

required mechanical properties and corrosion resistance. Among composites, Carbon FRP (CFRP) has

historically been the preferred solution for prestressed concrete applications. Nevertheless, the high

cost of carbon fiber, along with some technological drawbacks, may prevent the widespread use of this

technology.

This study lays within a comprehensive research effort investigating the application of Glass FRP

(GFRP) to mild-prestressed concrete elements (MPC). Glass fiber is an economical alternative to carbon

fiber in applications that do not require high level of concrete pre-compression. Limiting the level of initial

prestress would allow to overcome some constructability issues noticed with CFRP tendons, while the

reduced cost of glass would make it a competitive and durable alternative to standard steel strands.

This study focuses on the experimental investigation of GFRP strand prototypes anchored to the cross-

heads of the testing frame with conventional steel prestressing chucks (Figure 1). The aim is to verify

prototype compatibility with construction techniques traditionally applied to steel-PC. Both instantaneous

pull tests and sustained pull tests are presented. The prototypical nature of the strands is accounted for

in the data handling. The technology readiness level in association with possible field implementations

(i.e. mild-prestressed concrete sheet piles) is discussed. Comparison with traditional materials and

corrosion-resistant alternatives is considered.

Figure 5 – GFRP strand prototype cross section (a), comparison to a CFRP alternative (b), and prototype ready for pull test (c).




164


BEHAVIOR OF GFRP REINFORCED CONCRETE UNDER FLEXION:

EXPERIMENTAL TESTS ON REAL SCALE SLABS

M. Arduini 1 and G. Balconi 2

1 FRC LAB, CEO, Milano, Italy

2 Sireg Geotech, Research & Development, Arcore (MB), Italy, Email: [email protected]

KEYWORDS Field applications and case studies, Experimental

ABSTRACT Glass Fibre Reinforced Polymers (“GFRP) are currently widely used for reinforcing concrete structures.

Reinforcement designs and rebar diameters used in the field for this application vary significantly, lacking

mandatory material qualifications or limitations in the existing guidelines. In order to understand the differences

in performance of diverse GFRP reinforcement designs, flexion tests were carried out on six real dimension

concrete slabs. All reinforcements were designed for very similar flexural capacity but significantly different

GFRP-concrete adhesion area. In order to simulate an extreme case of potential material deterioration, the GFRP

bars employed had been aged outside for three years. Experimental results confirmed that, for reinforcements with

similar flexural capacity, an increase in the shape ratio implies a reduction in the maximum load capacity and the

occurrence of slip phenomena. A reinforcement with a high shape ratio may not guarantee a perfect bond between

concrete and GFRP, and experience premature slip phenomena.



- 165 -


LOAD DEFLECTION BEHAVIOUR OF SELF-CONSOLIDATING CONCRETE

BEAMS PRESTRESSED WITH CFRP BARS

S. Krem 1, K. Soudki 2 1University of Waterloo, Canada, Email: [email protected]

2 University of Waterloo, Canada, (was a professor at University of Waterloo 1997-2013)

KEYWORDS

Self-Consolidating Concrete, CFRP, Prestressed, flexural, deflection.

ABSTRACT

Self-consolidating concrete (SCC) offers a number of potential benefits that derive from its unique flow

characteristics: improved productivity and quality of concrete construction. The current ACI 440 design guidelines

does not account for SCC in flexural deflection predication of beams reinforced or prestressed FRP bars. This

paper presents measurements from four beams (150 × 250 × 3600 mm) prestressed with 12.7 mm CFRP bars: two

beams made from SCC and two beams made from normal vibrated concrete (NVC). All beams were tested under

a four-point static bending load under displacement control at a rate of 1.0 mm/minute. Measurements of load,

midspan deflection, strain in FRP bars, and strain in the concrete were collected using a data acquisition system.

Results was compared to two methods for flexural deflection predictions: Simplified method (ACI 440.4R-04),

and detailed analytical method from literature. The simplified method was based on effective moment of inertia

approximation while the detailed method was based on effective moment of inertia and effective centroid

calculations. Prediction of the midspan deflection based on the simplified method for SCC beams was

unconservative after cracking (service loads). The predicted of midspan deflection based on simplified method at

failure load differ by more than 30% of the experimental results for SCC beams prestressed to 30 and 60%. The

detailed method correlated well with experimental results at higher loads range for both types of concrete at both

prestressing levels.



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166


BOND BEHAVIOUR BETWEEN GFRP RODS AND CONCRETE

PRODUCED WITH SEAWATER: AN EXPERIMENTAL RESEARCH

José Sena-Cruz 2, Eduardo Pereira 1, Emanuel Pereira 1, Nelson Freitas 1, Sérgio Soares 1 1 ISISE, Department of Civil Engineering, University of Minho, Portugal (corresponding author:

[email protected])

KEYWORDS:

Bond behaviour, GFRP rods, concrete produced with seawater, direct pull-out tests.

ABSTRACT:

It is unquestionable that water is an indispensable natural resource for the existence of life on planet Earth, holding

enormous environmental, economic and social value. Today, with the increase of the population and consequent

increase in pollution, drinkable water is an increasingly sought-after and scarce resource. In this context, the need

to explore the potential of the direct use of seawater in the production of reinforced concrete (RC) structures

becomes evident. On the other hand, since the earliest times of universal history the sea constitutes the most

important space in world economic development, to which onshore and offshore structures are associated.

Structures when exposed to marine environments (e.g. ports, offshore structures, buildings located by the sea) are

subjected to the simultaneous action of several physical and chemical deterioration processes that accelerate their

degradation and greatly reduce their service life.

With the advent of fibre reinforced polymers (FRP), the construction industry has experienced a revolution due to

the countless advantages that these materials present, among which stands out their resistance to corrosion.

Therefore, the use of these new materials in RC structures exposed to marine environments may prevent the main

damages that aggressive agents typically originate in conventional RC, as well as to allow seawater to be directly

used in the design of concrete, thus avoiding the use of drinkable water.

In this work the possibility of using seawater in the design of RC structures, in combination to the use of glass

FRP (GFRP) rods, is explored. The research carried out included two phases: (i) the development of concrete

compositions including seawater and (ii) the assessment of the bond behaviour between GFRP rods and the

developed concrete. The present part is mainly devoted to the second phase where the influence of type of water

(tap water or seawater), the GFRP diameter and anchorage length on the bond between GFRP rods and concrete

were investigated. The main results obtained have shown that the use of seawater in the concrete composition had

no severe effects on the mechanical properties of the concrete and on the bond behaviour between the GFRP rods

and the concrete.

From concrete characterization tests it was concluded that the (i) the SW provided a higher cohesion, viscosity and

compactness to the fresh concrete. Results have indicated also that SW may have reduced the concrete setting time

and led to a faster development of its mechanical properties; (ii) compression tests performed at 28 days of age

showed that the concrete which included TW presented a higher value of compressive strength (≈+15%) and

modulus of elasticity (≈+7%).

From the direct pullout test results, the following conclusions can be highlighted: (i) three different failure modes

were observed, mainly debonding failure with total, partial or without failure of GFRP ribs; (ii) the larger GFRP

rod diameter provided the higher values of Fmax and τmax. Additionally, higher values of sl and Gf were also

obtained; (iii) the longer Lb provided an increase in Fmax. On the other hand, by increasing the anchorage length,

a larger contact surface between GFRP and concrete was mobilized and consequently lower τmax were obtained,

due to the non-linear distribution of the bond stresses along the anchorage length. Additionally, higher values of



Composites


167


sl and Gf were obtained; (iv) The use of SW instead of TW on the concrete mixture had influence

on the interface behaviour between GFRP and concrete. In the specimens where SW was included, lower Fmax

and τmax values were obtained. These reductions are directly related to the observed reductions in the concrete

mechanical strength at 28 days of age when SW was used. Nevertheless, it can be concluded that the use of SW

had no severe effects on the bond behaviour at 28 days after casting.

(a) (b)

Figure 1: Assessment of concrete properties at (a) fresh state and (b) hardened state.

(a) (b)

Figure 2: Results of pullout tests at 28 days: (a) concrete using tap water and (b) seawater.

Figure 3: Failure modes analysis.

0 2 4 6 8 10

0

20

40

60

80

100

Ø12_Lb5Ø_TW_1

Ø12_Lb5Ø_TW_2

Ø12_Lb5Ø_TW_3

Ø12_Lb10Ø_TW_1

Ø12_Lb10Ø_TW_2

Ø12_Lb10Ø_TW_3

Pu

llo

ut

forc

e, F

[kN

]

Loaded end slip, sl [mm]

0 2 4 6 8 10

0

20

40

60

80

100

Pu

llo

ut

forc

e, F

[kN

]

Loaded end slip, sl [mm]

Ø12_Lb5Ø_SW_1

Ø12_Lb5Ø_SW_2

Ø12_Lb5Ø_SW_3

Ø12_Lb10Ø_SW_1

Ø12_Lb10Ø_SW_2

Ø12_Lb10Ø_SW_3


Composites


168


FLEXURAL BEHAVIOR OF PULTRUDED GLASS FIBER-

REINFORCED POLYMER DISTRIBUTION POLES

Omar I. Abdelkarim1, Jose Manuel Guerrero2, Hamdy M. Mohamed3, Brahim Benmokrane4

1 Department of Civil Engineering, University of Sherbrooke, Quebec, Canada, J1K2R1.

[email protected]

2 Global PoleTrusion Group Corporation, Longueuil, QC, Canada J4N 1R2.

[email protected]


[email protected]


[email protected]

KEYWORDS

Utility poles; FRP; Composites; Fiber volume ratio; Finite element analysis.

ABSTRACT

This paper presents the behavior of pultruded GFRP distribution poles under flexural loading. Electrical and

telecommunication utility infrastructures, including poles, H-frames, and towers, are typically made of wood,

concrete, or steel. Each of these materials has several shortcomings due to their performances under the

environmental conditions and the difficulty of transportation. In addition, a significant number of the electrical

infrastructures in North America needs renewal in the coming few years because of their environmental

deterioration. Currently, the industry of the utility poles trends to build new infrastructures to be more reliable,

cost-effective, and sustainable. Glass fiber reinforced polymer (GFRP) composites for the utility infrastructures

represent a viable alternative to the traditional materials. However, the lack in the theoretical and experimental

data on the GFRP composite utility infrastructures delays their implementation. In this study, two identical full-

scale GFRP distribution poles Class C5 were tested under flexural loading. Also, the effect of the fiber volume

ratio on the load capacity of GFRP poles was investigated using finite element analyses. The tested poles had a

height of 10.5 m, a diameter of 254 mm, a thickness of 6.35 mm, and a fiber volume ratio of 0.40. The tested poles

exceeded the required strength as per the American National Standards Institute. A finite element (FE) model was

developed for the poles using MSC Nastran software. The FE validation showed a very good agreement with the

experimental results with accuracies of 98% and 95% for the prediction of the load capacity and maximum

displacement, respectively. The FE analyses showed that the moment capacity of the GFRP poles increased almost

linearly with increasing the fiber volume ratio.





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169


Masonry strengthening


Composites


170


NON-DIMENSIONAL AXIAL LOAD-MOMENT INTERACTION

DIAGRAMS FOR FRP STRENGTHENED MASONRY WALLS

Sonia Martínez 1, M. Dolores García2, J. Pedro Gutiérrez1 1 IETCC, CSIC. Eduardo Torroja Institute for Construction Science, Spain. Email: [email protected]

2 ETSAM, UPM. Superior Technical School of Architecture of Madrid, Spain

KEYWORDS :

Strengthening and repair; Design models; Masonry walls

ABSTRACT:

Masonry is a material with poor capacity to withstand tensile loads, for this reason it results so vulnerable against

destabilizing accidental loads, such as earthquakes. External FRP (fibre reinforced polymer) reinforcements can

improve out-of-plane flexural capacity of masonry walls. For practical applications, we need to study the critical

sections to check Ultimate Limit State is not exceeded. In this sense, non-dimensional axial load-moment

interaction diagrams are a useful tool for the design/assessment of the FRP reinforcement, as well as for analyzing

the incidence of the main variables on the ultimate cross sectional capacity. The diagrams included in this work

have been prepared from a calculation procedure similar to that used for reinforced concrete sections but adapted

to the particularities of the strengthened masonry ones. For masonry, an idealized bilinear stress-strain relationship

is used. For FRP strengthening, linear elastic up to failure, the design strain for flexural applications is limited by

a "bond reduction factor" taking into account some aspects, such as intermediate FRP debonding failure, that

causes the FRP sheets can’t reach their ultimate tensile strength although their ends were properly anchored. Non

dimensional axial load-moment interaction diagrams are presented, which main parameters have been chosen to

be representative of different FRP strengthening systems. These diagrams allow analyzing the predictable failure

mode (due to masonry or FRP) and the improvement of flexural sectional cross capacity obtained by means of the

strengthening depending on axial load level supported by the wall.

This work is part of the Project PIE 201760E066 funded by the Spanish National Research Council and the Project

BIA 2016-80310-P funded by AECI and FEDER.

Figure 1: Non-dimensional interaction diagram for FRP design strain equal to 0.006

f = f ffd /

fmd

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0

n= Nd / t b fmd

m=

Md /

t2 b

fm

d

efe = 0,006

AI

AII

region B

0,05

0,10

0,15

0,20

0,30

0,40

f = 0,50

f = 00,05

0,10

0,15

0,20


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171


EXPERIMENTAL RESEARCH INTO DYNAMIC PROPERTIES OF

NON-REINFORCED AND FRP REINFORCED MASONRY BARREL VAULTS

Jiří Witzany 1, Miroš Pirner 2, Radek Zigler 1, Shota Urushadze 2,

Jan Kubát 1, Klára Kroftová 3 1 CTU in Prague, Department of Building Structures, Prague, Czech republic;

2 The Institute of Theoretical and Applied Mechanics AS CR, v. v. i, Prague, Czech Republic; 1 CTU in Prague, Department of Architecture, Prague, Czech republic


KEYWORDS :

Dynamic properties, natural frequencies, masonry vaults, experimental research

ABSTRACT:

The analysis of dynamic behaviour of vaults of historic buildings and the results of dynamic loading is the objective

basis for identifying and locating faults and evaluating the operability and structural reliability of vaulted structures

of historic buildings.

Experimental results are an important basis not only for the numerical modelling and subsequent validation of the

computational model, but are also an important source of information for selecting an effective remediation method

of the vaulted structure. The results are of utmost importance especially for the vaults of historic buildings located

in seismically active areas, or in areas with intensive technical and induced seismicity (mining, quarrying,

transport).

The paper presents the results of experimental research (performed on vaults with a span of 3 m and a height 0.75

m) and theoretical analysis of the behaviour of unreinforced and FRP reinforced segmental masonry barrel vaults

and their failure mechanism under the effect of vertical monotonously rising loading and dynamic loading in the

horizontal and vertical directions.

Figure 1 : a) Mounting of the TIRAvib electrodynamic exciter on the vault, b) Distribution of sensors on the

vault, c) Oscillation shapes, theoretical and obtained from experiments, corresponding to the sixth natural

frequency


Composites


172


ANALYSIS OF THE MECHANICAL BEHAVIOR OF DIFFERENT BASALT-

TEXTILE REINFORCED MORTAR STRENGTHENING SYSTEMS

Carmelo Caggegi 1, Emma Lanoye1, Denise Sciuto2 1University Claude Bernard Lyon 1, Laboratory of Composite Materials for Construction (LMC2), Site Bohr, 82

Boulevard Niels Bohr, Campus de la DOUA, 69622 Villeurbanne Cedex, France.2 University of Catania,

Department of Civil Engineering, Italy(corresponding author: [email protected])

KEYWORDS

Strengthening and repair; Textile Reinforced Mortar ; Basalt fibers ; Digital Image Correlation, Effective bond

length

ABSTRACT:

In the last decades the use of fibre reinforced polymers (FRP) composites has been widespread for structural

applications. However in the case of historical masonry structures, the use of organic polymer based composites

is not advisable (lack of permeability, incompatibility between resins and substrate materials, no reversibility ofthe

intervention); thereby textile reinforced mortar (TRM) composites are becoming an effective and compatible

solution for masonry rehabilitation and their use has steadily increased over the past few years. TRM is becoming

also a new effective technical solution to reinforce other types of structures, for instance concrete structures.

The present study has been carried out to evaluate the influence of the substrate (masonry and concrete) on the

behaviour of a reinforced system characterized by a Basalt-Textile Reinforced Mortar (Fig.1) and to determine

some mechanical characteristics. Nine series of experimental shear bond tests have been carried out to define the

maximal strength, the failure mode and the effective bond length of different reinforced system. A Digital Image

Correlation analysis of the external composite surface has permitted to deeply define the evolution of cracking and

to have information about the effective bond length.

(a) (b)

Figure 1: (a) a specimen characterized by a masonry substrate (series MS); (b) a specimen characterized by a

concrete substrate (series CS).


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173


AN ANALYTICAL METHOD TO ESTIMATE THE RESISTING

BENDING MOMENT OF FRCM STRENGTHENED MASONRY WALLS

SUBJECTED TO OUT-OF-PLANE LOAD

Tommaso D’Antino1, Francesca Giulia Carozzi1, Pierluigi Colombi1, Carlo Poggi1 1 Politecnico di Milano, Department of Architecture, Built Environment, and Construction Engineering, Milan,

Italy; (corresponding author: [email protected])

KEYWORDS:

New composite materials, systems and strengthening techniques; Material; Codes, standards and design

guidelines; FRC and cement composite materials; FRCM; Masonry.

ABSTRACT:

A large number of existing masonry structures are in need of strengthening and retrofitting. A possible alternative

to traditional strengthening techniques is represented by the use of externally bonded fiber reinforced composites.

Between them, fiber reinforced cementitious matrix (FRCM) composites, which are comprised of high strength

fiber open meshes embedded within inorganic matrices, represent a promising solution to strengthen existing

masonry structures. Although FRCM composites were shown to be effective in strengthening unreinforced

masonry (URM) walls subjected to shear (in-plane load), bending (out-of-plane load), and predominant axial load,

the only design guideline available is the American ACI 549.4R-13. In this paper, an analytical procedure to

compute the resisting bending moment of URM walls strengthened with FRCM composites against out-of-plane

load is proposed. The analytical procedure is based on simple equilibrium conditions and takes into account the

characteristics of the masonry support and of the FRCM strengthening. The accuracy of the proposed procedure

is assessed by comparison between the experimental results of 49 FRCM out-of-plane strengthened masonry walls

collected from the literature and the corresponding analytical provisions. In addition, the experimental database

collected is employed to assess the accuracy of the analytical approach provided by the ACI 549.4R-13.

Figure 1: FRCM strengthened masonry wall.



174


DESIGN OF THE OUT-OF-PLANE STRENGTHENING OF MASONRY WALLS

WITH TEXTILE REINFORCED MORTAR (TRM) COMPOSITES

Stefano De Santis1*, Alessandro Bellini2, Gianmarco de Felice1, Claudio Mazzotti3, Pietro Meriggi1 1Roma Tre University, Department of Engineering, Rome, Italy; 2Alma Mater Studiorum University of Bologna,

CIRI Buildings and Construction, Bologna, Italy; 3Alma Mater Studiorum University of Bologna, Department of

Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy; *corresponding author:

[email protected]

KEYWORDS:

Seismic retrofitting; Analytical design relationships; Fabric Reinforced Cementitious Matrix (FRCM); Acceptance

criteria; Experimental tests

ABSTRACT:

Masonry walls are particularly vulnerable against out-of-plane seismic actions. Steel tie-bars can prevent their

overturning, but collapse may take place also by bending, leaf separation or disaggregation. In order to improve

the response with respect to these failure modes, Textile Reinforced Mortar (TRM) composites, comprising high

strength fabrics applied with inorganic matrices, can be used. TRMs, recently developed and already available in

the market, can be efficiently integrated with traditional techniques and, when lime-based mortars are used, are

compliant with the preservation criteria required for applications to historic structures. A number of experimental

investigations have been carried out in the last decade, making use of different textile materials, matrices,

substrates, and experimental setups, showing the effectiveness of mortar-based composites for improving both

load and displacement capacity (Figure 1). Nevertheless, apart from the ACI 549.4R-13 guide, no instructions

addressed to practitioners have been developed for the design of the out-of-plane reinforcement of masonry walls

with externally bonded TRM systems. This paper proposes an approach for the assessment of the flexural capacity

of a masonry wall reinforced with TRM and subjected to compression and bending. The design properties of the

reinforcement are derived by combining the results of standard direct tensile tests and shear bond tests. Analytical

predictions are compared to experimental results to discuss the reliability of the proposed methodology and

calibrate a tuning coefficient that accounts for the possible occurrence of an intermediate debonding failure in the

TRM, which cannot be observed in small-scale bond tests. The outcomes of this work could contribute to the

development of a design guide for the repair and strengthening of existing masonry structures with Textile

Reinforced Mortars, which is currently underway within a Liaison ACI 549 – Rilem TC 250-CSM subcommittee,

as well as within other European and national committees.

Figure 1: Full-scale tests on masonry walls reinforced with TRM: Babaeidarabad et al., J Compos Constr,

2014;18,4,04013057 (a), Bellini et al., Int J Archit Herit, 2017 (b), and De Santis et al., Earthq Eng Struct Dyn,

2016;54,2,229-251 (c).

(a) (b) (c)



175


CONFINEMENT OF EXISTING RC AND MASONRY COLUMNS WITH FRCM

COMPOSITES: ACI-RILEM PROVISIONS

Maria Antonietta Aiello1 and Lesley H. Sneed2 1 Department of Engineering for Innovation, University of Salento, Lecce, Italy (corresponding author:

[email protected]); 2Missouri University of Science and Technology, Department of Civil,

Architectural and Environmental Engineering, Rolla, MO 65409, USA

KEYWORDS :

Confinement, Concrete, Design, FRCM, Masonry

Mini-Symposium: TRM/FRCM for Strengthening Masonry Structures

ABSTRACT:

The use of fiber reinforced cementitious mortar (FRCM) composites for repair/retrofitting existing reinforced

concrete (RC) and masonry structures has gained increasing interest, especially in cases for which breathability,

reversibility, higher temperature resistance, and higher compatibility with the substrate are key issues. An

important application of FRCM composites is the confinement of columns; the use of a fiber mesh applied with

an inorganic matrix around the column affords higher hoop strength that contrasts the transversal deformation

induced by the compressive load acting on the column. Fibers provide high tensile strength, and failure of the

confined column usually occurs by fiber rupture. However, the matrix also plays a crucial role; in fact when the

mortar cracks, sliding of the fibers within the matrix may occur leading to an uneven distribution of tensile stress

between the fibers and a consequent decrease of the confining pressure. The mechanical behavior of FRCM makes

the available models/relationships for FRP-confined columns generally inconsistent with the case of FRCM-

confined columns. Recent efforts have been made within the scientific community to investigate the response of

FRCM-confined columns, and on the basis of available results, ACI guidelines have been published to support

their design. On the other hand, scientific and technical commissions are also working in Europe, and in some

cases in conjunction with the related ACI committees, to harmonize design approaches and extend design

relationships to existing structures typical of European countries.

In this work the most relevant design issues related to FRCM confinement of RC and masonry columns are

discussed in light of available experimental and theoretical results. Design relationships for American and

European guidelines are presented, and the state of the work of the joint ACI-RILEM committee focusing on this

topic is discussed. Finally, critical aspects are identified to provide suggestions for future research and technical

work.



176


DESIGN RULES FOR IN-PLANE SHEAR STRENGTHENING OF MASONRY WITH

FRCM

G.P. Lignola1, M. Di Ludovico1, A. Prota1, M.A. Aiello2, A. Cascardi2, G. Castori3, M. Corradi3 1 University of Naples “Federico II”, Department of Structures for Engineering and Architecture, Napoli, Italy,

Email: [email protected] 2 University of Salento, Department of Engineering for Innovation, Lecce, Italy

3 University of Perugia, Department of Engineering, Perugia, Italy

KEYWORDS

Strengthening and repair, modelling, codes, standards and design guidelines, characterization of FRP and FRC

materials/systems

ABSTRACT

Textile Reinforced Mortar and Fiber Reinforced Cementitious Matrix composites (FRCM) are nowadays

considered as a viable solution to enhance in-plane strength of masonry walls where they are bonded to. Such

composites are usually applied to the entire surface of the wall, bonded to one side of the wall or to both sides.

The past experimental activity demonstrated that there is a significant improvement of the in-plane strength even

applying a single layer of material to the sides of the walls, but not wide consensus has been found on the modelling

of these benefits for code and design guidelines purpose. Great effort has been put in defining simple models,

practitioner oriented, and the present paper aims at comparing the ACI549 and novel RILEM proposal. The main

crucial issue is the evaluation of an effective contribution of the strengthening solution to the as built in-plane

capacity of masonry walls. It is in fact expected that different substrates (both in terms of materials as in terms of

thickness and basic properties of the wall) has an impact on the efficiency of a strengthening system (characterized

by another variability of parameters like as fiber type, grid and mortar matrix geometrical and mechanical

properties). In this effort, main parameters governing the in-plane response are first recognized; hence a simple

mechanical model is proposed to fit the typical average experimental behaviour of TRM/FRCM strengthened

masonry walls in-plane loaded. Finally the impact of uncertainty and variability of results is analysed to propose

appropriate coefficients for design uses.




177


STRUCTURAL BEHAVIOR OF FRP REINFORCED RING BEAMS

Antonio Borri1, Marco Corradi1*, Giulio Castori1, Vikki Edmondson2

1 University of Perugia, Department of Engineering,Via Duranti 93, 06125 Perugia, Italy; 2 Northumbria

University, Department Mechanical & Construction Engineering, Newcastle upon Tyne

* corresponding author: [email protected]

Keywords :

New composite materials, systems and strengthening techniques;Experimental study ; Seismic applications;

Characterization of FRP and FRC materials/systems

ABSTRACT:

The building structural capacity against horizontal forces can be effectively improved by means of introduction of

ring beams. By connecting load bearing walls with ring beams, it is possible to form a box-like container within

the volume defined by the walls and to prevent out-of-plane collapse mechanism of a single wall panel. Different

types of rings beams have been proposed in the past to increase the load capacity of historic masonry constructions

and box-like structures have previously proven to perform well under seismic action. The most common type of

ring beams is made of steel rebar reinforced concrete (RC). This retrofitting method has been widely used in the

last thirty years in many seismic prone areas, but several issues arose during earthquakes for the different

mechanical behaviour, mainly in terms of deformation, of the coupled materials (masonry and RC). In this paper

the structural behavior of simply supported masonry-made ring beams reinforced with fiber reinforced polymer

(FRP) materials are illustrated. Extensive research has shown that FRP are effective for strengthening historic

masonry structures and this technique is now widely used around the world in many different applications.

However, a potentially useful application of FRP for reinforcement of ring beams has received only limited

attention to date. This paper presents an experimental study carried out in the laboratory and funded by the Italian

Reluis programme. The aim is to identify a retrofitting method for historic masonry buildings, which, while

improving structural capacity against horizontal forces, will not significantly alter the stiffness properties of the

building and its structural components and it will meet the requirements imposed by the conservation bodies in

terms of reversibility and compatibility with original masonry. The experimental investigation was conducted in

the laboratory on two groups of full-scale ring beams, made of stone and brick masonry. Bending tests have

demonstrated that it possible to assemble masonry FRP-reinforced beams. High bending capacities have been

recorded with limited flexural stiffness.



178


FRP CONFINEMENT OF CLAY BRICK MASONRY COLUMNS UNDER AXIAL

LOAD: EXPERIMENTAL RESULTS

Jennifer D’Anna1, Giuseppina Amato2, Jian Fei Chen2, Lidia La Mendola1, Giovanni Minafò1

1University of Palermo, Department of Civil, Environmental, Aerospace, Material Engineering (DICAM),

Palermo (Italy); (corresponding author: [email protected]) 2School of Natural and Built Environment David Keir Building, Queen’s University Belfast (UK);

KEYWORDS :

Strengthening and repair; Experimental study ; Characterization of FRP and FRC materials/systems;

ABSTRACT:

Composite materials constitute a valid alternative to traditional systems thanks to the many advantages they can

offer. In particular, the use of composite materials for structural upgrading has become a common practice for

retrofitting masonry columns and piers. The target of this method is to improve the axial capacity and the local

ductility of the material by inducing a passive confinement action. This system has shown significant capabilities

since its origin, due to the great tensile strength of composite and consequently to the high values of confinement

pressure achievable.

The estimate of the effective collaboration of FRP wrap and the evaluation of the ultimate strength of the structure

was the subject matter of several experimental researches. However, in relation to the number of parameters

governing the failure mechanism (kind of brick element and mortar layer, dimension of columns and so on) the

experimental studies carried out on this topic are not enough to formulate a general theoretical model.

This paper presents the results of an experimental study on the compressive behaviour of clay brick masonry

cylinders reinforced with basalt fibre reinforced polymer (BFRP) grids. The main aim of this study is to assess the

effectiveness of the BFRP wraps on the strength and ductility of masonry columns. Twelve clay brick masonry

cylinders, cored from masonry walls and columns, were reinforced using either one or two layers of BFRP grids.

Two different arrangements were used for producing the cylinders in order to investigate the effect of vertical

joints on the response of masonry cylinders. The basalt grid had a cell size of 6x6 mm. After a preliminary

experimental study aimed at characterizing the mechanical properties of bricks, mortar and basalt grid, the

cylinders were tested under uniaxial compression loading. The test results showed a strength increase between

30% and 38% for cylinders wrapped with one layer and between 69% and 71% for those wrapped with two layers

of BFRP grids.

a)

b) c)

Figure 1. Specimens preparation and setup: (a) scheme I; (b) scheme II; (c) test setup




179


REPAIR OF A MASONRY WALL WITH AN INNOVATIVE CIMENT BASED

COMPOSITE

Jean-Patrick Plassiard1, Olivier Plé 1, Pascal Perrotin 1 1 1Univ. Savoie Mont Blanc, CNRS, LOCIE, F-73000 Chambéry, France

KEYWORDS :

New composite materials, systems and strengthening techniques; Material ; FRC and cement composite materials;

Characterization of FRP and FRC materials/systems cement composite with steel grid ; numerical simulations

ABSTRACT:

This study focuses on the ability of a cement based composite to repair a damaged wall, previously submitted to

in plane shear loading. The composite associates a stainless steel grid with a repairing mortar. Sample tests show

that this combination provides a strong ductility, a strain hardening behaviour and fire resistance to the composite.

First, the masonry wall tested is submitted to a cantilever test, until the maximal shear resistance is reached. The

corresponding failure exhibits cracks that correspond to a transition between a flexural failure mode and a diagonal

failure mode. Then, the wall is repaired with the composite moulded directly on the wall. After the curing time, a

new cantilever test is performed. The strength of the repaired wall increases about ten per cent. Moreover, the

stiffness of the wall is improved while its ductility increases significantly. In order to evaluate the damage of the

composite, the digital image correlation was used. No failure was noticed inside of the repaired area during the

loading, giving the wall its better strength.

The modelling of the experiment is planed currently, by using a finite element approach. The main objective is to

evaluate the effect of the composite on the shear strength, depending on the wall slenderness, the vertical loading

and the failure pattern observed before the repair phase.

Figure 1 : Reparation of the masonry wall and loading curves for the initial and repaired wall



180


DESIGN CRITERIA FOR STRENGTHENING OF MASONRY VAULTS WITH

TEXTILE REINFORCED MORTAR

G. de Felice1, F. Focacci2, M. Malena1, G. Tomaselli1, M.R. Valluzzi3*

1Roma Tre University, Dept.of Engineering, Rome, Italy.

2 eCampus University, Novedrate (CO), Italy

3University of Padova, Dept of Cultural Heritage, Padova, Italy,

*Email: [email protected]

ABSTRACT

Textile Reinforced Mortar (TRM) also known as Fabric Reinforced Cementitious Matrix (FRCM) represents a

valid alternative to Fiber Reinforced Polymers (FRP) for structural strengthening. The use of inorganic matrix in

place of epoxy resin produces a substantial advantage in terms of physical and chemical compatibility with the

substrate, especially for application to masonry members (walls or vaults). However, the increasing use of TRM

systems for repair and strengthening of masonry structures is carried out in the absence of specific rules for design

and assessment. Aiming at filling this lack in regulation, a joint committee between ACI 549 and RILEM TC250

was established.

Based on the experimental results and modelling approaches available in the literature, a preliminary database of

the significant parameters characterizing the mechanical behaviour of TRM/FRCM systems applied to masonry

vaults was collected. More precisely, the load and displacement capacity of masonry vaults strengthened with

FRCM composites are put in relationship with the mechanical parameters characterizing the tensile and bond

properties of the strengthening systems.

In such a framework, the following relevant aspects are considered: i) the contribution of the strengthening system

in terms of additional capacity of the vault with respect of the delamination phenomenon; ii) the influence of the

curvature on the capacity of the reinforcement and on its bond to the substrate; iii) the comprehensive effect on

the overall deformability of the strengthened structure. Based on the collected data, an analytical approach is

proposed to draw up simplified design rules that can be used for application to real cases.



181


AXIAL COMPRESSIVE BEHAVIOR OF RECYCLED BRICK BLOCK CONCRETE-

FILLED FRP TUBES

T. Jiang 1, X.M. Wang 2, G.M. Chen 3, F.M. Ren 4, W.P. Zhang 5 1 Space Structures Research Center, Department of Civil Engineering, Zhejiang University, Hangzhou, China

(corresponding author: [email protected]) 2 Space Structures Research Center, Department of Civil Engineering, Zhejiang University, Hangzhou, China 3 School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, China

4 School of Civil Engineering, Guangzhou University, Guangzhou, China 5 School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, China

KEYWORDS :

Recycled brick block; Compound concrete; FRP tube; Confinement; Compressive behavior

ABSTRACT:

Waste bricks are one of the largest sources of China’s construction and demolition (C&D) waste. This study

attempts a new recycling method in which the waste bricks are directly used in their full size or only crushed into

blocks that are distinctly larger in size than normal-sized aggregate (recycled brick blocks, RBBs) for mixing with

fresh concrete to form new compound concrete (recycled brick block concrete, RBBC). RBBC generally features

weaker mechanical properties and greater discreteness compared with normal concrete due to the relatively low

strength and large size of RBBs. To improve the performance of RBBC, this study proposes the use of an outer

FRP tube as both the stay-in-place formwork and the confining device for RBBC (i.e. RBBC-filled FRP tubes,

RBBCFFTs). In order to understand the compressive behavior of RBBCFFTs, 36 standard cylinder specimens

were tested under axial compression with the experimental variables being the replacement ratio of RBBs (0, 10%,

20%) and the FRP tube stiffness (0, 1, 2, 3 plies). The test results show that the compressive strength and the

deformability of RBBC can be significantly improved by FRP confinement. However, RBBCFFTs show larger

discreteness in compressive behavior than normal concrete-filled FRP tubes mainly due to the large difference in

strength between the RBBs and the fresh concrete (approximately 45 MPa) and the inhomogeneous spatial

distribution of the RBBs. The test results also show that the stress-strain curves of the RBBCFFT specimens feature

a bilinear shape. The first portion of their stress-strain curves appears elongated compared with the bare RBBC

specimens. This phenomenon may be due to the delay in formation of the major cracks in RBBC when it is

confined in an FRP tube, allowing the integrity of RBBC to be kept till a higher axial stress level than when the

FRP tube is absent.

Figure 1 : Casting of specimens



182


Figure 2 : Failure mode of typical specimens (replacement ratio = 20%)

Figure 3 : Stress-strain curves of typical specimens (replacement ratio = 10%)

-0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.020

10

20

30

40

50

60

70

80

90

Lateral Strain e l Axial Strain ec

Axia

l S

tre

ss

c (

MP

a)

D150R10C0-1,2,3

D150R10C1-1,2,3

D150R10C2-1,2,3

D150R10C3-1,2,3



183


AN EXPERIMENTAL STUDY ON THE COMPRESSIVE BEHAVIOUR OF

CALCARENITE MASONRY COLUMNS WRAPPED BY FIBER REINFORCED

MORTAR WRAPS

Giovanni Minafò*, Lidia La Mendola, Dionisio Badagliacco, Alessia Monaco, Calogero Cucchiara

University of Palermo, Department of Civil, Environmental, Aerospace, Material Engineering (DICAM),

Palermo (Italy); (corresponding author: [email protected])

KEYWORDS

Strengthening and repair; Experimental study ; Characterization of FRP and FRC materials/systems;

ABSTRACT:

The use of Fiber Reinforced Cementitious Mortar (FRCM) systems for structural retrofitting of masonry structures

has become increasingly popular in the last years, due to the capability of this technique in overcoming some of

the drawbacks related to the adoption of resin-based composites. In fact, FRCM systems ensure good compatibility

between the reinforcing layers and the substrate, achieving also the removability requirement, which is of

fundamental importance for historical constructions. Recent research studies focused on the mechanical

performance of FRCM materials, by studying its tensile behaviour and bond between the strengthening layer and

masonry, pointing out as failure is always reached due to loss of bond with different mechanisms, the latter

depending on the physical properties of FRM and masonry. Further studies investigated on the effect of FRCM

wraps on the compressive behaviour of concrete members and demonstrated as the application of mortar-based

composites allows increasing strength and, above all, the ductility of the column. The main difference with FRP

confined columns is related to the different post-peak behaviour, characterized by a softening branch. Differently,

few studies are actually available on the literature on the efficiency of FRCM confinement in enhancing the

compressive behaviour of masonry columns.

This paper presents the result of an experimental investigation on the effect of FRCM wraps on the compressive

behaviour of calcarenite masonry columns. A preliminary study on the mechanical performances of the

strengthening layer is performed by selecting three different mortar grades for the FRM and testing these under

flexure and compression. Moreover, tensile tests on the glass fibre fabric and on FRM strips are performed to

characterize the behaviour of the reinforcing system. Finally, eleven columns are tested under concentric

compression, recording the axial strain, and discussion is made on modes of failure and gains of strength and

ultimate strain.

a) b)

Figure 1. Specimens and test set-up

a) Specimens before strengthening; b) Test set-up.



184


EXPERIMENTAL INVESTIGATION OF THE ROLE OF MORTAR JOINTS IN TRM-

MASONRY BOND

Paraskevi Askouni1, Catherine Papanicolaou 1 1 University of Patras, Department of Civil Engineering, Rio, Greece (Paraskevi Askouni: [email protected])

KEYWORDS :

Textile Reinforced Mortar; Masonry; Shear bond tests; Mortar joints

Mini-Symposium: TRM/FRCM for Strengthening masonry Structures”

ABSTRACT:

Textile Reinforced Mortar (TRM) is a composite material that has already gained popularity as externally bonded

reinforcement for structurally deficient masonry structures. TRM qualifies for use in this field since it can fulfil

requirements related to compatibility with various masonry substrates and reversibility of the intervention.

However, the exploitation ratio of the material significantly depends on the bond between the externally bonded

textiles and the existing substrate. For this reason, an experimental campaign has already been deployed by the

authors investigating the shear bond behavior of TRM-masonry interfaces; TRM comprises a dry glass fibre textile

embedded in a cement-based mortar and masonry consists of smooth solid clay bricks. To this end, a double-

lap/double-prism shear bond test set-up has been employed. This work focuses on the investigation of a parameter

that has received minimal attention in the literature, namely the role of the substrate in the response of the TRM-

masonry system under direct shear. Specifically, the role of mortar joints is investigated through varying the mortar

joints’ area as a percentage of the total bonded one. The findings of this work (applicable to masonry with smooth

bricks of low porosity) seem to challenge a commonly accepted notion according to which the substrate plays

insignificant role in the shear stress transfer mechanism provided that failure is due to slippage of the textile within

the mortar layer. The results obtained show that for all bond lengths considered the increase of the mortar joints’

area leads to a non negligible increase of the maximum axial textile stress at failure, failure mode remaining

unchanged (textile slippage).

0 5 10 15 20 25200

250

300

350

400

BL 250 mm (_

Linear Fit)

BL 150 mm (_

Linear Fit)

BL 100 mm (_

Linear Fit)

Ma

xim

um

ax

ial

tex

tile

str

es

s (

MP

a)

joints/TRM bonded area (%)

(α)

Figure 1 : Maximum axial textile stress vs. joints/TRM bonded area ratio for bond lengths 250 mm, 150 mm and

100 mm



185


OUT-OF-PLANE BEHAVIOR OF RM WALLS STRENGTHED WITH FRCM

COMPOSITE OR NSM WITH CEMENTITIOUS ADHESIVE

Zuhair Al-Jaberi 1, John J. Myers 2, and Mohamed ElGawady 3 1 PhD Candidate, Department of Civil, Architectural &Environmental Engineering, Missouri University of

Science and Technology, MO, USA 2 Professor, Department of Civil, Architectural &Environmental Engineering, and Associate Dean at Missouri

University of Science and Technology, MO, USA 3 Associate Professor, Department of Civil, Architectural &Environmental Engineering, Missouri University of

Science and Technology, MO, USA

KEYWORDS:

Strengthening or repair; Experimental study; Masonry; FRCM; NSM.

ABSTRACT:

Twelve reinforced masonry (RM) walls strengthened in flexure using a Fabric-Reinforced Cementitious Matrix

(FRCM) composite or the Near Surface Mounted (NSM) technique with a cementitious adhesive. These were built

as a part of this experimental study. FRCM strengthening composite materials consisted of one or two plies of

carbon or PBO (polyparaphenylene benzobisoxazole) fabric embedded in cementitious mortar. The NSM

technique consisted of carbon or glass bar encapsulated in slots that had been grooved into the masonry tension

surface .For all these specimens, a constant mild steel reinforcement ratio (ρ) was used. These simply supported

walls were tested under an out-of-plane cyclic load that was applied along two line loads. The key parameters for

this investigation were the type and amount of fabric, and bond pattern (stack and running). The behavior of the

specimens is discussed with emphasis on the load-deflection response, and changes in stiffness and flexural

capacity. The test results indicated that the behavior of the masonry walls was significantly dependent on the type

of fabric used. Different modes of failure occurred in the strengthened reinforced walls, including crushing of

concrete block, as well as a debonding of FRP from the masonry substrate and slippage of fabric within

cementitious matrix.

INTRODUCTION:

In the civil engineering field, the need for the upgrading capacity and strengthening of structural elements has

become a critical issue. Fiber reinforced polymer (FRP) composites has recognized as viable solution for

strengthening and upgrading the capacity of infrastructure projects. Although epoxy adhesive was played the major

role as an effective bonding agent and was proved in many applications for strengthening of masonry structures,

it has some disadvantages. These include hazardous poor behavior of epoxy at the glass transition temperature,

inability to be applied on wet surface, emission of toxic fumes, moisture impermeability and flammability

(Hashemi and Al-Mahaidi, 2008, Al-Jabari et al., 2015, Al-Abdwais and Al-Mahaidi, 2016). In order to overcome

these disadvantages of FRP and epoxy system, FRCM or NSM with cementitious material adhesive has emerged

as a solution. Turco et al. (2006) compared the behavior and modes of failure of URM walls strengthened in flexure

with NSM and two different embedding materials (latex modified cementitious paste and epoxy-based paste).

Approximately similar results were achieved by using epoxy or cementitious paste as a bonding adhesive. The

dimension of the groove should be increased in case of using the cementitious paste. FRCM is a second generation

of externally-bonded retrofitting technique and complementary to FRP systems. Retrofitting of URM concrete or

clay brick walls with FRCM under uniformly distributed lateral load was investigated by (Babaeidarabad and

Nanni, 2015), who reported an enhancement in flexural capacity of range 2.7-7.8 compared to unstrengthened

specimens. The main objective of this investigation is to study experimentally the behavior of RM walls

strengthened with FRCM composite or NSM with cementitious adhesive.

EXPERIMENTAL PROGRAM:

This study considers tests and comparison on 12 reinforced masonry walls specimens, 10 of which were

strengthened in flexure with either FRP NSM bars (glass or carbon) or with FRCM (PBO or carbon). The

reinforced walls were tested under cyclic load up to failure. Each specimen were constructed using 152.5 mm (6



186


in.) standard masonry blocks in running or stack bond pattern and type S mortar. The nominal dimensions of these

walls were 1220 mm (48-in.) in height and 610 mm (24-in.) length. 2#4 reinforced fully grouted steel bars were

installed four days after wall construction.

Strengthening Procedure

The procedure of FRCM strengthening was consisted of applying first layer of cementitious matrix with a nominal

thickness of approximately 5 mm (0.2-in.) on the bottom surface of the specimen. 1- Ply of pre-cut fabric was laid

on the cementitious matrix, and then second layer of cementitious matrix with a nominal thickness of 5 mm (0.2-

in.) was applied on the fabric. The procedure was repeated in case of multi-ply strengthening. No surface

preparation needed for NSM system and the strengthening procedure involved inserting FRP bar into a groove cut

at the tension surface of the specimen. The cementitious was placed into the grooves to cover 2/3 of the groove

height. The FRP bar was installed in the grooves and pressed to force the adhesive to flow around the bar and

ensure completely bond between the bar and the sides of the groove. The groove is then filled with more adhesive

and the surface levelled.

Test setup and Loading Protocol

Four-point line loading with simply supported boundaries can be used to conduct out-of-plane testing of reinforced

masonry walls. The load was applied in half-cycles of loading and unloading, as a displacement control at a rate

of 1.27 mm/min.

RESULTS AND DISCUSSION

The general behavior of walls strengthened with FRCM or NSM system is a ductile behavior. The ductile behavior

is due to existence of steel reinforcement and gradual loss of composite action caused by slippage of fiber within

matrix or debonding failure. The debonding occurred at the bonding matrix/fiber interface in case of strengthening

using FRCM system while, it’s at FRP bar/cementitious adhesive interface in case of NSM. For both systems, the

stack and running pattern’s behave as the same response in terms of ductility but in term of capacity, the running

specimen got a little more flexural capacity as shown in Fig. (1). The behaviour of stack specimen improved when

the head joint was reinforced with an FRP bar or the tension face strengthened with PBO fabric sheet.

(a) (b)

Figure 1. Load-displacement curves for specimens strengthened with (a) NSM, (b) FRCM

CONCLUSIONS

Test results indicated that FRCM and NSM systems remarkably increase the lateral load capacity of reinforced

masonry walls. Moreover, the strengthening systems were effective in enhancing the stiffness of strengthened

walls. The flexural capacity was increased by 172% for specimens strengthened with NSM while its double in case

of FRCM strengthening compared to the control wall. The failure mode was identified as a debonding failure for

all specimens strengthened with NSM and slippage or debonding for specimens strengthened with FRCM.

0 1 2 3 4 5 6 7 8 9

0

16

32

48

64

80

0

3

6

9

12

15

18

0 1 2 3 4

Displacement (cm)

Load

(k

N)

Load

(K

ip.)

Displacement (in.)

G2-2SG2-2Rcontrol-R

0 3 6 9

0

15

30

45

60

75

90

0

3

6

9

12

15

18

21

0 0,5 1 1,5 2 2,5 3 3,5

Displacement (cm)

Load

(k

N)

Load

(k

ip)

Displacement (in)

PBO(380)-2RPBO(380)-2Scontrol



187


REVERSIBLE FRP-CONFINEMENT OF HERITAGE MASONRY COLUMNS

Alessio Cascardi 1, Riccardo Dell’Anna 1, Francesco Micelli 1*,

Francesca Lionetto 1, Maria Antonietta Aiello 1, Alfonso Maffezzoli 1 1 University of Salento, Department of Innovation Engineering, Lecce – Italy.

KEYWORDS

confinement; masonry; heritage; reversibility; frps abstract

Heritage building is mainly made-up of historical masonry structures, which largely demonstrated their

vulnerability in case of seismic events in the last centuries. In this type of applications, the choice of the most

appropriate retrofitting technique is strongly limited due to the requirements of preserving the cultural and artistic

value. In this scenario, the design of Fiber Reinforced Polymers (FRPs) application is, definitely, not always

allowed because of the adhesive matrix that attaches the fiber to the masonry substrate and implies loss of material

when the removability is a mandatory issue. In FRP-strengthening, the matrix is mainly responsible for the

strength transfer from the substrate to the fibers by means of bond stresses. In case of column confinement, the

bond is generally assured despite it is not needed for the confinement effectiveness, since it is an application that

requires only contact between the compressed core and the confining jacket. In fact, the confining pressure is

provided by the FRP when transversal dilatation of the column is recorded; so, the retrofitting works due to

contact-phenomenon and not due to bond.

In this perspective, different alternative FRP-confinement techniques, based on preventing adhesion, can be

developed. The present paper aims to illustrate and describe three full-reversible FRP-confinement innovative

techniques: the FRP-filament-winding (FW) with ultrasonic welding, the interposing of a MylarTM sheet and the

surface treatment with a liquid adhesion inhibitor, which may protect the stone without losing his breathability.

The effectiveness of the confinement action was proved by means of experimental tests on small-scale masonry

columns; while the reversibility of the intervention is attested by the substrates comparison between the

unconfined columns and these one after the compression test. The results of traditional wet lay-up jacketed

columns are compared and discussed with the results obtained by applying the proposed techniques.

Figure 1: Detail of the loss of material: traditional (right) and innovative (left) confinement.

.



188


INVESTIGATION ON THE FRCM-MASONRY BOND BEHAVIOUR

F. Nerilli 1 and B. Ferracuti 2 1 Niccolò Cusano University, Via Don Carlo Gnocchi, 3, Rome, Italy, Email: [email protected]

2 Niccolò Cusano University, Via Don Carlo Gnocchi, 3, Rome, Italy.

KEYWORDS

New composite materials, Systems and strengthening techniques; Material ; FRC and cement composite materials;

Bond and interfacial stresses, Masonry panels

ABSTRACT

In the last decade, the scientific community has posed great attention on Fiber Reinforced Cementitious Matrix

(FRCM, made with a fiber mesh embedded in inorganic matrix). The good chemical and mechanical

characteristics make the FRCM suitable for structural application as strengthening material for existing structures.

In literature, results of different experimental campaigns on the mechanical characterization of FRCM are

available, in terms of tensile tests and FRCM-masonry bond tests. Basing on the second ones, it is worth pointed

out that the failure mode can change with respect of the components that constitute the composite. In detail, a

differentiation has emerged on the debonding behaviour of FRCM with respect to the most common FRP (Fiber

Reinforced Polymer), for which a cohesive debonding that interests the support can occur. This difference makes

the provisional formulations defined for the FRP-masonry debonding, not directly applicable for the FRCM-

masonry systems.

Aim of this paper is to frame the mechanical behaviour of the FRCM reinforcement with regards to its tensile

strength and debonding behaviour, when applied on masonry structural elements. A large database, based on the

experimental results of tensile tests and of debonding tests, is collected and presented. The data are analysed,

focusing the attention on those relative to the most frequent debonding failure mode, similar to those observed on

the structural elements reinforced by FRCM. Moreover, a critical analysis of the specimen geometry, mechanical

properties and different test setups adopted in the various available experimental campaign with the aim of

subdivided the database in homogenous data for better understand the bond behaviour between FRCM and

artificial/natural masonry blocks.

.




189


Seismic retrofitting



190


EFFECTIVENESS OF A NOVEL ANCHORAGE SYSTEM FOR FLEXURAL

STRENGTHENING OF RC BEAM-COLUMN JOINTS USING CFRP sheets

Alireza Akhlaghi1, Davood Mostofinejad 1 1 Isfahan University of Technology, Department of Civil Engineering, Isfahan, Iran (corresponding author:

[email protected])

KEYWORDS :

Strengthening and repair; Experimental study ; Seismic applications; EBROG; Flexural strengthening

ABSTRACT:

Fiber-reinforced polymer (FRP) composites are widely exploited in engineering practice for enhancing flexural

strength of reinforced concrete (RC) members. However, their application to increase the flexural strength of code-

compliant RC beam-column joints is stipulated by current codes and guidelines. The main issues of concern that

still await resolution include provisioning appropriate anchorage details for FRP composites at beam-column

interface, debonding of FRP composites off the concrete substrate, and effect of cyclic load reversal on FRP

reinforcement. The present experimental study was conducted to investigate the efficacy of carbon-FRP (CFRP)

anchor fan as a novel anchorage system at beam-column joint interface strengthened in flexure with CFRP sheets

installed on top and bottom sides of the beam where the plastic hinge is expected to form at the column face.

Furthermore, in order to avoid any likely debonding of FRP composites off the concrete substrate in tension or

buckling in compression, surface preparation of the test specimens was performed according to recently developed

grooving method (GM) in the form of externally bonded reinforcement on grooves (EBROG). For the purposes of

this study, two half-scale RC beam-column subassemblies were constructed. These included one control specimen

and two rehabilitated ones that were tested under constant axial compression and reversed cyclic lateral loading of

increasing amplitudes. The results indicated that the adopted rehabilitation strategy enhanced remarkably the

lateral strength and cumulative energy dissipation capacity of RC joints, thus confirming the efficiency of the

suggested anchorage system as well as the surface preparation method. In addition, the proposed scheme is capable

of effectively relocating the plastic hinge away from the column interface into the beam.



191


GFRP-RC EDGE SLAB-COLUMN CONNECTIONS SUBJECTED TO SEISMIC

LOADING

Mohammed El-Gendy1, Ehab El-Salakawy 1 1 University of Manitoba, Department of Civil Engineering, Winnipeg, Canada


KEYWORDS :

All FRP and smart FRP structures; Experimental study; Seismic applications; FRP internal reinforcement;

punching shear; edge slab column connection

ABSTRACT:

The elastic nature of fibre-reinforced polymer (FRP) reinforcement raises concerns about the feasibility of using

this type of reinforcement in reinforced concrete (RC) structures subjected to seismic events, where significant

amount of energy needs to be dissipated. Recent studies on FRP-RC beam-column connections and column

elements demonstrated adequate overall seismic response of such structural elements, particularly using glass (G)

FRP. To date, however, no studies have been conducted to investigate the seismic response of FRP-RC slab-

column connections.

This paper presents the results of an experimental program carried out to assess the seismic response of slab-

column edge connections reinforced with GFRP reinforcement. Two isolated full-scale RC slab-column edge

connections were constructed and tested under gravity and reversed-cyclic lateral loading conditions. One

connection was reinforced with conventional steel reinforcement (Connection ES), while the other one was

reinforced with the same flexural reinforcement ratio of GFRP reinforcement (Connection EG); both connections

had no shear reinforcement and were subjected to a constant gravity shear ratio of 40%, as listed in Table 1. The

dimensions of the connections were 3,300 × 3,100 × 200 mm with a 300-mm square column extending above and

below the slab. Figure 1 shows Connection EG secured to the test setup before the beginning of the test. As shown

in Figure 2, Connection EG failed in punching shear at a drift ratio of 2.5%, which is higher than the 1.5%

minimum drift ratio suggested in the literature for steel-RC connections subjected to 40% gravity shear ratio. This

indicates the ability of the GFRP-RC slab-column edge connections to undergo or exceed the suggested seismic

drifts while maintaining their gravity load carrying capacity.

Table 1: Details of test connections

Connection Reinforcement

type

Negative reinforcement

Ratio (%)

Concrete strength

(MPa)

ES Steel 0.66 45.2

EG GFRP 0.74 45.8



192


Figure 1: Test setup

Figure 2: Hysteretic response of Connection EG

-40

-30

-20

-10

0

10

20

30

40

-4 -3 -2 -1 0 1 2 3 4

Late

ral Load (

kN

)

Drift Ratio (%)



193


MECHANICAL CHARACTERIZATION OF A RC WALL-SLAB JOIST

REINFORCED BY FRP UNDER ALTERNATING CYCLIC LOADING

A.Chalot, L.Michel, E.Ferrier, C.Caggegi, N.Reboul, C.Grazide

Laboratoire des Matériaux Composites pour la Construction, LMC²

Université LYON 1

82 boulevard Niels BOHR, Site de Villeurbanne DOUA, 69622 VILLEURBANNE Cedex

e-mail : [email protected] et [email protected]

KEYWORDS :

Strengthening and repair; Experimental study ; Seismic applications;

ABSTRACT:

The strengthening of reinforced concrete structures by composite materials in the seismic applications is an

increasingly used solution thanks to the high performances of composite materials. At present, the behavior of

beams in bending or shearing, column in bending or confined, or slabs are well known in the literature. Design

methods dealing with the reinforcement of elementary elements (beams, columns, slabs, walls) are even developed

and available for the engineer. On the other hand, it is still very difficult to define the global behavior of the

strengthening at the scale of the building. Previous research shows that the reinforcement of the elementary

elements transfers the damage or the ruptures towards the joists between elements. In this case anchoring systems,

for example, shows a good improvement in the structural bonding response of FRP. On the other hand, it is still

very difficult to precisely characterize the impact of reinforced elementary elements and reinforced joists in the

overall response of the structure.

This paper presents the results of an experimental study for the characterization of wall-slab joists made of

reinforced concrete subjected to alternating cyclic loadings in order to characterize the impact of FRP

strengthening on this kind of joist. For this, 6 specimens were made and tested to failure. A reference specimen

and 5 different reinforcement configurations by composite materials are compared in order to assess the changes

in the maximum recovered loads, the displacements or the different dissipated energies. Aims to obtain a boundary

factor allowing to calculate the global response of a building.

Figure 1 : Wall-slab joist detail




Composites


194


CIRCULAR AND SQUARE GFRP-REINFORCED CONCRETE COLUMNS

SUBJECTED TO SIMULATED SEISMIC LOADS

Zahra Kharal1, Shamim Sheikh1 1 University of Toronto, Department of Civil Engineering, Toronto, Canada

KEYWORDS:

All FRP and smart FRP structures; Experimental study; Seismic applications; Codes, standards and design

guidelines; Ductility;

ABSTRACT:

A huge inventory of concrete structures exist in many parts of the world that have been made deficient due to steel

corrosion. Columns in these structures are especially critical for seismic resistance. In this research, use of GFRP

as longitudinal and lateral reinforcement in columns has been investigated as an alternative to steel.

The experimental program includes seventeen 356 mm diameter and sixteen 305 mm square concrete columns

tested under constant axial load and cyclic lateral displacement excursions simulating earthquake forces. Each test

was terminated only when the column was unable to support the axial load. All the columns were reinforced

laterally with GFRP spirals or rectilinear ties. Nine circular and two square columns contained longitudinal GFRP

bars while eight circular and fourteen square columns had longitudinal steel bars. Other variables included level

of axial load, amount of confining reinforcement, spacing of transverse reinforcement and reinforcement

configuration. While columns containing GFRP longitudinal and GFRP lateral reinforcement demonstrated

excellent post elastic stable response accompanying large deformability, they displayed softer responses with

lower shear and flexural capacity compared with columns that contained steel longitudinal bars. At larger

deformations, GFRP performed better as confining reinforcement compared with steel in similar columns that

were tested and reported in an earlier study. This is due to the fact that GFRP lateral reinforcement continues to

provide increasing confining pressure with increased deformations while steel yields at approximately 0.002 strain

and allows the concrete to expand and lose resistance. In addition, GFRP transverse reinforcement did not rupture

in any of the specimens tested with GFRP longitudinal bars while lateral steel has been reported to have ruptured

in several columns.

Results from a select group of specimens will be presented in this paper to highlight the effects of different

variables and establish the feasibility of using GFRP in columns for seismic resistance.



195


MODELING PARAMETERS AND ACCEPTANCE CRITERIA FOR FRP-

RETROFITTED CONCRETE COLUMNS SUBJECTED TO SEISMIC LOAD

Benben Li1,2 and Kent A. Harries2,3 1Tongji University, Research Institute of Structural Engineering and Disaster Reduction, Shanghai, China

2University of Pittsburgh, Civil and Environmental Engineering, Pittsburgh, USA, Email: [email protected] 3University of Bath, BRE Centre for Innovative Construction Materials, Bath, UK

KEYWORDS

STRENGTHENING AND REPAIR, STANDARD, SEISMIC APPLICATIONS, CODES, STANDARDS AND

DESIGN GUIDELINES

ABSTRACT

External wrapping of fibre reinforced polymer (FRP) is widely applied for the seismic retrofit of reinforced

concrete columns. Although ASCE 41 – Seismic Evaluation and Retrofit of Existing Buildings provides

recommendations for the nonlinear modelling of deformation behaviour of conventional reinforced concrete

columns under seismic load, there is no available guidance for the evaluation of seismic performance following

FRP retrofit. Using the methods promulgated by ASCE 41, nonlinear modeling of FRP-retrofitted concrete

columns is studied. In the nonlinear model curve, parameters a, b and c are used to represent nonlinear behavior.

Defining parameter a, the plastic rotation representing the limit of acceptable structural behavior (collapse

prevention (CP) performance level), is the focus of this work. A database of 116 large- and full-scale FRP-

retrofitted concrete columns – all exhibiting flexure-dominate behavior – was established. Factors influencing

plastic rotation (and therefore parameter a) were systematically studied, including axial force ratio, effective

transverse reinforcement ratio and normalized design shear force. An empirical relationship for plastic rotation

was established.



196


SEISMIC RESPONSES OF THE POST-YIELD HARDENING SINGLE DEGREE OF

FREEDOM (SDOF) SYSTEMS INCORPORATING FRP MATERIALS

H.L. Qiang 1, P. Feng 1, Z. Qu 2 and L.P. Ye 1 1 Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Department of Civil

Engineering, Tsinghua University, Beijing 100084, China. Email: [email protected]. 2 Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics,

China Earthquake Administration, Yanjiao, Sanhe, Hebei 065201, China.

KEYWORDS

FRP, post-yield stiffness, single degree of freedom (sdof), peak displacement, residual deformation

ABSTRACT

The improvement to seismic capacity of the structures by ductility design is widely accepted in the world.

Nevertheless, the inelastic deformations of structures also bring serious damages to the structures. In recent years,

application of fibre reinforced polymer (FRP) materials represents an important choice in the performance-based

design, damage control and seismic resilience enhancement of structures. Many materials, members and structures

incorporating both FRP and conventional materials show significant post-yield hardening (PYH) behaviors.

However, the findings and conclusions of previous studies on structures with elastic-perfectly plastic (EPP)

behavior or little post-yield stiffness may not lend themselves to PYH structures. The post-yield stiffness of the

structure needs to be taken into account as an important primary structural parameter in addition to the initial

stiffness, yielding strength and ductility. In this paper, extensive time-history and statistics analysis are carried out

for PYH single degree of freedom (SDOF) systems. The peak displacement and residual deformation responses

are obtained and discussed. Theoretical model are also established. These models provide a basis for developing

the appropriate seismic design and performance evaluation procedures for PYH structures.

.



197


REPAIR AND STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH

THE USE OF TEXTILE REINFORCED MORTARS (TRM’S)

Theofanis Krevaikas 1 Xi’an Jiaotong Liverpool University, Civil Engineering dept., Jiangsu Suzhou 215011, (corresponding

author: Theofanis.Krevaikas @xjtlu.edu.cn)

KEYWORDS:

Strengthening and repair; Experimental study ; FRC and cement composite materials; Codes, standards and

design guidelines

ABSTRACT:

In the aftermath of strong earthquakes beam elements suffer from severe damage which is mainly attributed

to low shear strength. Appropriate intervention schemes are sought to regain initial strength and stiffness. A

promising and innovative method is to externally apply textile reinforced mortars (TRMs) to increase both

the flexural and the shear strength. In this paper, the results of an ongoing experimental programme are

presented. A total of eight Reinforced Concrete (RC) beams with four different reinforcement ratios, were

subjected to four-point bending up to failure. Subsequently the RC beams were repaired with the use of patch

repair mortars and epoxy resins. In the next stage Basalt fibers in the form of textiles embedded in

cementitious mortars were externally applied to increase both the flexural and the shear strength of the beams.

One and two layers of TRMs were used. In the final stage, the beams were loaded up to failure using a four

point bending set-up. The experimental results showed that the beams regain their initial stiffness and most

of their original strength, proving that the use of TRMs is an effective alternative for strengthening statically

deficient RC elements.

198

Steel strengthened structures



199


FATIGUE TESTS ON STEEL PLATES WITH AN INCLINED CENTER CRACK

REPAIRED WITH CFRP STRAND SHEETS

Tao Chen1, Lingzhen Li 1, Ningxi Zhang 1 , Yuya Hidekuma 2 1 Department of Structural Engineering, College of Civil Engineering, Tongji University, Shanghai, China

(corresponding author: [email protected]) ; 2 Nippon steel & Sumikin Materials Co., LTD. Composites

Company, Tokyo, Japan

KEYWORDS :

Strengthening and repair; Fatigue ; Experimental study ; Inclined crack; CFRP strands

ABSTRACT:

Carbon fibre reinforced polymer (CFRP) has been adopted as an idea materials for fatigue improvement of cracked

steel structures. Considering the complexity of initial cracks and stress field around crack tips, mixed mode fatigue

behaviour were investigated by conducting fatigue tests on steel plates with an inclined centre crack repaired with

CFRP strands. Steel plates were artificially cut from a centre hole with five different angles. All of the cracks had

an identical projection length on the direction perpendicular to the load. Specimens were patched with CFRP

strands on single side or both sides. The effects of repairing schemes and CFRP types were studied by comparing

fatigue lives, crack lengths, crack trajectories and failure modes. It was found that fatigue crack propagation life

was mainly determined by the projection length of initial crack on the direction perpendicular to the load. Whereas,

the effect of initial inclined crack's angel has negligible influence on the fatigue life.

Figure 1 : Test setup



200


FACTORS INFLUENCING BOND OF CFRP TO STEEL

Manuel A G Silva1, Pedro Ribeiro 2, Hugo Biscaia 3 1 Universidade Nova de Lisboa (FCT), Civil Engineering,Caparica, Portugal; Email [email protected]

2 Universidade Nova de Lisboa (FCT), Civil Engineering,Caparica, Portugal; 3 UNIDEMI (UNL), Departmen tof Mechanical and Industrial Engineering, Caparica, Portugal;

ABSTRACT

Many infrastructures require structural strengthening, e.g (Miller et al., 2001; Libby and Mullins, 2001; Bank,

2006; Kirk and Mallet, 2007), and the use of fiber reinforced polymers on that endeavor has been growing in spite

of uncertainties related to their lifetime behavior. An example of major concern is the premature debonding of

external strengthening of structures under adverse environmental conditions, a type of failure that may occur when

carbon fiber reinforced polymers (CFRP) are used in the strengthening of steel structures, namely bridges. Failure

of those CFRP-steel structural members may occur at the joints and this study examines factors that alter or explain

reduction of the load capacity of the latter, namely surface treatment prior to bonding, the glass transition

temperature (Tg) of the adhesive, the exposure to freeze-thaw (FT) cycles that artificially accelerate aging of the

components, and raising operating room temperature to near Tg. An experimental program was undertaken to

analyze the influence of these factors on the mechanical performance of the joints. The steel surface was subjected

to sand blasting (6.3bar), and abrasive grinding (6.9bar) Sa 2, to compare with no treatment, and the case of rust

induced by ten days exposure to salt fog was also considered. Tests made at different temperatures allowed

comparison of ultimate capacities of strains and failure modes, confirming rapid deterioration. The quantification

of the losses of mechanical resistance was made essentially by shear tests of double strap specimens. Adhesion

failures after FT were analyzed and compared. Evolution of Tg along FT aging showed negligible changes, in

general. Scanning electronic microscope images were used to help interpret results. In particular after 2,000 and

5,000 cycles of FT, for Ca, Si and O, a decrease of Si from the reference specimens 18.8% to 13.3% and 10.2%

was noticed while Ca showed 14.2%, 10.2% and 16.1%, but such preliminary values would require many

additional data to allow conclusive statements. Results are summarized and compared with those in available

literature.




201


EXPERIMENT STUDY ON BOND BEHAVIOR BETWEEN CFRP PLATE

AND STEEL

Yuyang PANG1, Gang WU2, Haitao WANG3

1 Ph.D. Candidate, Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of

Education, Southeast University, Nanjing, China;2 Professor, Key Laboratory of Concrete and Prestressed

Concrete Structures of the Ministry of Education, Southeast University, Nanjing 210096China (corresponding

author). E-mail:[email protected];3Lecturer College of Civil and Transportation Engineering, Hohai University,

Nanjing, China

KEYWORDS :

Strengthening and repair; Material ; Prestressing with FRP composites; Bond and interfacial stresses

ABSTRACT:

To investigate the influencing factors of CFRP delamination failure in CFRP-to-steel, extensive CFRP-to-steel

specimens were tested in this paper. The main factors considered are the types of CFRP plates and adhesives.

Effects of the tensile strength of the CFRP plate, and mechanical properties (i.e. the strength and elastic modulus)

of the adhesive on failure modes are evaluated. The three-dimensional digital image correlation (3D-DIC)

technique was used to measure the displacements and strains of the specimens. Test results show that the failure

occurred within the CFRP layer, the ultimate load of the non-linear adhesive specimens is consistent basically,

while the ultimate load of the linear adhesive specimens increases with the tensile strength of CFRP plate. At the

same time, the experiment also revealed the load-displacement curve of CFRP-to-steel.

Figure 1: Stress-strain relationship of adhesive



202


STUDY ON REPAIR METHOD FOR CORRODED GUSSET PLATE CONNECTION BY

BONDING CFRP SHEET

Ngoc Vinh PHAM1, Takeshi MIYASHITA2, Kazuo OHGAKI3, Yusuke OKUYAMA4, Akira KOBAYASHI5, Yuya

HIDEKUMA6, Takeshi HIROSE7, and Takuya HARADA8

1 Ph. D. Candicate, Nagaoka University of Technology,

1603-1, Kamitomioka, Nagaoka, Niigata, 940-2188, JAPAN

E-mail: [email protected] 2 Associate Professor, Nagaoka University of Technology,

1603-1, Kamitomioka, Nagaoka, Niigata, 940-2188, JAPAN 3 Professor, Institute of Technologists,

333 Maeya, Gyoda City, Saitama, 361-0038, JAPAN 4 Assistant Professor, National Institute of Technology, Nagano College,

716 Tokuma, Nagano City, 381-8550 JAPAN 5 General Manager, Nippon Steel & Sumikin Material Co.,

7-16-13, Ginza, Chuo-ku, Tokyo, 104-0061, JAPAN 6 Chief, Nippon Steel & Sumikin Material Co.,

7-16-13, Ginza, Chuo-ku, Tokyo, 104-0061, JAPAN 7 General Manager, Nippon Expressway Research Institue Co.,

1-4-1 Tadao, Machida-shi, Tokyo, 194-8508, JAPAN 8 Nippon Expressway Research Institue Co.,

1-4-1 Tadao, Machida-shi, Tokyo, 194-8508, JAPAN

KEYWORDS :

Carbon Fiber Reinforced Plastic (CFRP), Steel truss bridges, Corroded gusset plate connection, Repair method, Finite

element analysis (FEA).

ABSTRACT:

In steel truss bridges, several severe damage due to corrosion at the gusset plate connection have been reported. The

reduction of load-carrying capacity of the gusset plate connection is confirmed to lead to the collapse of the entire truss

bridge. The collapse of I-35W steel truss bridge (in the USA, 2007) is considered a typical case because of the insufficient

gusset plate thickness that resulted lower load-carrying capacity of the connection. The attachment of stiffening plate and

member replacement are some of the traditional methods often applied to repair corroded structures. However, these repair

works lack in workability because of heavy machinery and welding facilities. Therefore, this study focused on investigating

the effectiveness of repair method by using carbon fiber reinforced polymers (CFRP) for the corroded gusset plate

connection. Loading test in the laboratory and FEM analysis with a model of approximately 1/2 size of real bridge, and the

degree of corrosion assumed about to 50% and 75% of the gusset plate thickness, were conducted. This study proposed

two CFRP bonding methods, including out-side bonding and both-sides bonding; to improve the load-carrying capacity of

the gusset plate connection. From the experiment and FEA, when the thickness of gusset plate reduced by 50% and 75%,

the load-carrying capacity declined significantly compared to the intact case. In the large corrosion cases, the two proposed

repair methods were able to increase the load-carrying capacity dramatically. The improvement rates were 55.5% and

74.7% respectively. Conversely, the load-carrying capacity of the small corrosion cases was not improved considerably.

The proposed repair methods recovered the initial stiffness and the out-of-plane stiffness of the corroded gusset plate

connection. In addition, the experimental results also show that the two proposed repair methods can increase the Yield

point load on the corroded section of the gusset plate. Furthermore, this study clarified that the experimental result and the

failure behavior of the gusset plate connection could be reproduced by using the finite element method.




203


FRACTURE ANALYSIS OF SINGLE-EDGE CRACKED TUBULAR STEEL BEAM

REHABILITATED BY CFRP SHEETS

Mahdi Razavi Setvati1, Zahiraniza Mustaffa2 and Dokyun Kim3 1,2&3 Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, 32610

Seri Iskandar, Perak, Malaysia (corresponding author: [email protected])

KEYWORDS:

Stress Intensity Factor; Tubular Steel Beam ; CFRP; Composite Patch Repair

ABSTRACT:

The application of fiber reinforced polymer (FRP) composites for repair of structural elements has become

essential in recent years. However, most of the research focused on using pultruded FRP plates, which are limited

in repairing structures with flat surfaces. In this research, a three-dimensional finite-element approach was

proposed to calculate the stress intensity factor of single-edge cracked tubular steel beam before and after repair

with unidirectional carbon fiber reinforced polymer (CFRP) sheets. Results indicated the efficiency of CFRP patch

sheets in terms of reducing stress intensity of the single-edge cracked tubular steel beam.




204


FEASIBILITY OF ACCELERATED CURING FOR STRENGTHENING OF STEEL

MEMBERS BY PRESTRESSED BONDED CFRP PLATES

Ardalan Hosseini 1,2, Elyas Ghafoori 1, Abdola Sadeghi Marzaleh 1, Masoud Motavalli 1,3 1 Structural Engineering Research Laboratory, Empa, Dübendorf, Switzerland (corresponding author:

[email protected]); 2 Resilient Steel Structures Laboratory, EPFL, Lausanne, Switzerland; 3 School of

Civil Engineering, University of Tehran, Iran

KEYWORDS:

Strengthening and repair; Experimental study; Prestressing with FRP composites; Bond and interfacial stresses;

Accelerated curing (AC); Digital image correlation (DIC)

ABSTRACT:

Bond behavior and anchorage resistance of prestressed CFRP plates to steel substrate have been investigated in

the current study. To do so, a set of single lap-shear and prestress release tests was performed on CFRP-to-steel

bonded joints, and the feasibility of accelerated curing (AC) of epoxy adhesive by heating was investigated.

Furthermore, a set of so called mixed bond tests, with partial prestress release and subsequent lap-shear, was

performed to examine the practicability of prestressed strengthening of steel members using AC. A 3D digital

image correlation (DIC) technique was used to monitor the bond behavior of prestressed CFRP to steel during

prestress release and subsequent lap-shear tests. Experimental results of the current study revealed that AC of

epoxy adhesive by heating can be a promising alternative to the conventional room temperature curing (RTC) for

strengthening of steel members with externally bonded CFRP plates. It is evident that in prestressed strengthening

projects, the prestressing system needs to stay in place to keep the prestressing force constant over the curing of

the adhesive. Therefore, AC is certainly beneficial in reducing the required time and cost of such strengthening

solutions. Based on the experimental results of the current study, a relatively fast practical solution for

strengthening of existing steel members with prestressed bonded CFRP reinforcements is proposed.

Figure 1: Heat distribution in a steel I-profile during accelerated curing of epoxy adhesive used for bonding a

prestressed CFRP plate to steel substrate

Heating

device IPE 220

600 mm




205


GLASS TRANSITION EVALUATION OF COMMERCIALLY AVAILABLE EPOXY

ADHESIVES FOR STRENGTHENING OF STEEL STRUCTURES WITH BONDED

CFRP PLATES

Ardalan Hosseini 1,2, Michel Barbezat 3, Julien Michels 1,4, Elyas Ghafoori 1, Masoud Motavalli 1,5, Giovanni

Terrasi 3 1 Structural Engineering Research Laboratory, Empa, Dübendorf, Switzerland (corresponding author:

[email protected]) 2 Resilient Steel Structures Laboratory, EPFL, Lausanne, Switzerland

3 Mechanical Systems Engineering Laboratory, Empa, Dübendorf, Switzerland 4 re-fer AG, Brunnen, Switzerland

5 School of Civil Engineering, University of Tehran, Iran

KEYWORDS:

Strengthening of steel structures, characterization of epoxy adhesives, dynamic mechanical thermal analysis

(DMTA), tensile mechanical properties, room temperature curing (RTC), accelerated curing (AC) by heating.

ABSTRACT:

Epoxy adhesives with relatively high stiffness and almost linear stress-strain behavior are typically used for

strengthening of concrete members with externally bonded carbon fiber reinforced polymer (CFRP) composites.

However, utilization of low stiffness and high toughness non-linear epoxy resins can be more efficient for bonding

CFRP plates to steel substrate. The reason is attributed to the fact that contrary to CFRP-concrete joints, CFRP-

to-steel bonded joints often fail due to the fracture of the adhesive layer, and not of the substrate. This means that

application of low stiffness and high toughness epoxies can reduce the stress concentration in the adhesive layer,

and hence increase the ultimate bond capacity of the joint by further distributing the interfacial shear stresses along

the bonded length. On the other hand, a CFRP-strengthened steel structure can be subjected to moderately elevated

temperatures during its service life. Therefore, in order to achieve a reliable strengthening solution, the stiffness

reduction of the utilized epoxy adhesive with respect to temperature increase, or in general, the glass transition

behavior of the epoxy resin needs to be properly estimated. In the current study, the glass transition behavior of

three different two-component epoxies, commercially available as structural adhesives for CFRP strengthening of

concrete and steel structures, has been investigated. A set of dynamic mechanical thermal analysis (DMTA) tests

have been performed, through which the glass transition behavior of two high toughness epoxies, suitable for steel

strengthening, was compared to a typical high stiffness adhesive for concrete applications. In addition to DMTA

tests, a set of tensile tests was also performed on dogbone specimens to evaluate and compare the tensile

mechanical behavior of the selected epoxy adhesives. Furthermore, the influence of two different curing scenarios

(i.e., room temperature curing (RTC), and accelerated curing (AC) by heating) on the glass transition temperature

as well as tensile mechanical properties of all the three epoxy adhesives was investigated. Based on the

experimental results of the current study, certain recommendations are proposed to select a proper epoxy adhesive

for strengthening of steel structures with bonded CFRP composites.




206


(a) (b)

Figure 1: (a) DMTA, and (b) tensile test setup.

Epoxy sample

Load cell

Temperature chamber

Test specimen

Clip gauge

Mechanical clamp



207


FASSTBRIDGE METHODOLOGY AND STRENGTHENING SYSTEM: THE

JARAMA BRIDGE EXPERIENCE

David García-Sánchez1, Mazen Wabeh2, Frank Lehmann 3 Sylvain Chataigner4, Luis Sopeña5, Veit Birtel6

1 FUNDACION TECNALIA RESEARCH AND INNOVATION (TECNALIA) Calle Geldo, Edificio 700, Parque Tecnologico de Bizkaia, 48160, Derio, Spain

[email protected] 2ALTAVISTA SOLUTIONS

3260 Blume Drive, Suite 500, 94806, Richmond, USA 3LEONHARDT, ANDRÄ UND PARTNER BERATENDE INGENIEURE VBI AG (LAP)

Rosenthaler Str. 40/41, 10178, Berlin 4 INSTITUT FRANÇAIS DES SCIENCES ET TECHNOLOGIES DES TRANSPORTS, DE L'AMENAGEMENT

ET DES RESEAUX (IFSTTAR) Route de Bouaye, 44344, Bouguenais, France

5 DRAGADOS S.A. Avda. del Camino de Santiago 50, Building 4, 2nd Floor, 28050, Madrid, Spain

6 MPA UNIVERSITAET STUTTGART (USTUTT)

Pfaffenwaldring 32, 70569, Stuttgart, Germany

KEYWORDS :

Steel bridge; fatigue; residual life; life time extension; CFRP

ABSTRACT:

Steel bridges present frequent fatigue problems that reduce their load-carrying capacity and residual life. The

increase of traffic flows and loads in the last decades has enhanced this problem, especially on ageing structures.

This phenomenon is very dangerous because a conventional structural stress analysis might result in misleading

conclusions about safety. In Europe 15% of the 300 000 bridges are made of steel or concrete-steel composite

structures, and approximately 68% of them need structural interventions. In the USA, figures are quite similar.

Having this in mind, in November 2015, the ERA-NET Plus project FASSTBRIDGE was launched aiming at

developing a complete methodology including a calculation method for assessing the remaining life of steel bridge

in terms of fatigue, a designing and applying method for the strengthening intervention, and a strengthening system

relying on the use of adhesively bonded CFRP (Carbon Fiber Reinforced Polymer).

The paper presents the FASSTbridge methodology and strengthening system, which have been designed to work

with codes based on The American Association of State Highway and Transportation Officials (AASHTO) or the

European Union's Eurocode and its implementation in Jarama Bridge (Madrid, Spain). Indeed, this methodology

is an evolution of the existing probabilistic and deterministic methods. It means an advance from the analysis based

on the standard load model to the more precise load approaches getting an easy assessment with satisfactory

accuracy level facilitating a real preventive assessment of existing steel bridge.

The innovation of FASSTbridge is to provide an integral and complete solution which embraces the whole process,

from the assessment of possible fatigue damage to the maintenance of the applied strengthening system to achieve

a sustainable and cost-effective preventive strategy for life time extension of steel bridges.



208


PROPOSAL OF A METHODOLOGY BASED ON FINITE ELEMENT ANALYSES

FOR THE DESIGN OF BONDED CFRP REINFORCEMENT OF STEEL CRACKED

ELEMENTS

Emilie Lepretre1, Florent Chemin2, Sylvain Chataigner2, Lamine Dieng2, Laurent Gaillet2 1 CEREMA, DTech ITM, Sourdun, France; 2 IFSTTAR, MAST Department, SMC Laboratory, Bouguenais,

France (corresponding author: [email protected])

KEYWORDS :

Strengthening and repair; Fatigue; Characterization of FRP and FRC materials/systems; Finite element modelling

ABSTRACT:

Recent studies have shown the efficiency of the application of carbon fiber reinforced polymer (CFRP) materials

to reinforce cracked steel elements even in the case of old steel materials (mild steel and puddled iron). Bonding

CFRP materials on cracked steel plates leads indeed to a significant reduction of the stress intensity factor (SIF)

at the crack tip and thus to a significant increase of the fatigue life. This is even more pronounced when using

ultra-high modulus or prestressed reinforcement. This could allow extending damaged steel structures service life

or securing a structure waiting for a more complete refurbishment. Yet, there is currently a clear lack of design

tools for the design office to be able to apply such reinforcement or repair technique.

The presented work concerns the appraisal of a methodology based on the use of finite element modeling to

determine the stress intensity factor modification ratio. After the presentation of the proposed methodology, it will

be compared with experimental investigations led by the authors on different steel substrates and with different

reinforcement processes. Similar comparison will then be done with results from the literature to identify the

precision of the method, and to be able to highlight its strengths and weaknesses. Finally, parametric analyses will

be done to assess the impact of different design characteristics on the increase of fatigue life.

Figure 1 : Finite element model and comparison of experimental and modelling results



209


DEFINITION AND ASSESSMENT OF AN ADHESIVELY BONDED COMPOSITE

REINFORCEMENT IN FATIGUE FOR STEEL STRUCTURES DEVELOPPED IN

FASSTBRIDGE PROJECT

Sylvain Chataigner1, Karim Benzarti2, Gilles Foret2, Jean-François Caron2, Gianluca Gemignani3, Matteo

Brugiolo3, Veit Birtel4, Frank Lehmann4, Inigo Calderon5, Ignacio Piniero5 1 IFSTTAR, MAST department, SMC Laboratory, Bouguenais, France; 2 IFSTTAR, MAST department, Navier,

Marne La Vallée, France; 3 Collanti Concorde, Vittorio Veneto, Italy; 4 MPA, Stuttgart, Germany; 5 TECNALIA,

Bilbao, Spain; (corresponding author: [email protected])

KEYWORDS

Strengthening and repair; Experimental study ; Characterization of FRP and FRC materials/systems; Durability,

long-term performance

ABSTRACT:

One of the aims of Infravation project called FASSTbridge (Fast and effective Solution for the Strengthening of

existing steel bridges) is to develop a specific reinforcement system dedicated to the preventive fatigue

reinforcement of steel bridges. The proposed system relies on the use of an adhesively bonded composite plate.

The adhesive has been specifically formulated by Collanti Concorde within the project to respect the required

fulfillments of the studied application. It is combined with a commercially available composite plate.

The communication will first give insight of the required properties of the adhesive, the composite plate, and the

overall system for the considered application. Based on these requirements and existing literature and standards

on the topic, the chosen experimental plan will be described. It includes investigations on the adhesive before

curing, the adhesive after curing, the composite plate, and the whole reinforcing system. Both short term and

durability investigations were carried out by the different partners implied within the projects. The obtained results

will be presented, and allowed verifying the system properties. The participation of different partners to the

experimental campaign also gives insight of the encountered dispersion, and allowed studying different parameters

that may affect the capacities. The reinforcement system is forecast to be applied on a real bridge in Spain.

Figure 1 : Photos of one of the used test setting and of double lap shear samples



210


MODEL UNCERTAINTY OF EXTERNALLY BONDED CFRP-TO-STEEL JOINTS

Qian-Qian Yu 1, Dongming Zhang 2, Xiang-Lin Gu 3, Hongwei Huang 2 1 Key Laboratory of performance Evolution and Control for Engineering Structures, Ministry of Education,

China; Department of Structural Engineering, Tongji University, Shanghai, China (corresponding author:

[email protected]); 2 Department of Geotechnical Engineering, Tongji University, Shanghai, China; 3

Key Laboratory of performance Evolution and Control for Engineering Structures, Ministry of Education,

China; Department of Structural Engineering, Tongji University, Shanghai, China

KEYWORDS

Strengthening and repair; Modeling ; Bond and interfacial stresses; Characterization of FRP and FRC

materials/systems; CFRP-to-steel; Model factor

ABSTRACT:

This paper presents a study of the model factor ε for bond strength model of carbon fibre-reinforced polymer

(CFRP)-to-steel joints, which is defined as the ratio of tested bond strength to the predicted result by the models.

A total of 402 single/double-lap shear tests of externally-bonded joints were collected to evaluate the statistics of

ε and two frequently used models in literature were compared. Specimens with cohesive failure, adhesion failure,

CFRP delamination as well as combined failure were included. The statistics of ε indicate a high level of both the

mean value and coefficient of variation (COV). It was found that the model factors of the models with a relatively

high COV value (larger than 0.3) were not random, but heavily dependent on the input parameters.



211


STRESS INTENSITY FACTOR FOR DOUBLE-SIDED CRACKED STEEL BEAM

STRENGTHENED WITH CFRP PLATES

Hai-Tao Wang1, Gang Wu2, Yu-Yang Pang 2 1 Hohai University, College of Civil and Transportation Engineering, Nanjing, China (corresponding author:

[email protected]); 2 Southeast University, Key Laboratory of Concrete and Prestressed Concrete

Structures of the Ministry of Education, Nanjing, China;

KEYWORDS :

Strengthening and repair; Fatigue ; Characterization of FRP and FRC materials/systems; Durability, long-term

performance

ABSTRACT:

The externally-bonded carbon fiber reinforced polymer (CFRP) technique has been used to repair damaged steel

structures in recent years. Many studies have verified the effectiveness of this technique for prolonging the fatigue

life of cracked steel elements. The fatigue life of cracked steel elements mainly depends on the stress intensity

factors at the crack tip according to fracture mechanics theory. In this paper, the finite element (FE) and theoretical

analysis were conducted to evaluate the stress intensity factors of double-sided cracked steel beams strengthened

by CFRP plates. A three-dimensional FE model was developed to calculate the stress intensity factors. The effects

of the CFRP thickness and elastic modulus, adhesive thickness and adhesive shear modulus on the stress intensity

factors were considered in the EF analysis. According to the calculation equations of the stress intensity factors

for the cracked steel plates with double-sided cracks, a simplified calculation method was proposed to calculate

the stress intensity factors of cracked steel beams with double-sided cracks by simplifying the tension flange of

steel beam to a tension steel plate. Finally, the proposed equations were verified by the FE results. The predicted

results were compared with the numerical results. The comparisons demonstrate that the proposed equations can

predict the stress intensity factors of double-sided cracked steel beams strengthened by CFRP plates with

reasonable accuracy.

(a) CFRP-strengthened steel plate (b) simplified CFRP-strengthened steel beam

Figure 1 : Schematic of the specimens

2l

2b

aa

2ts

tfta

tf

ta

CFRP plate

Steel plate Steel plate

Adhesive

σ0

σ0

σ0

σ0

CFRP plateTension flange

Constraint effect of the web

σ0 σ0



212


IMPROVEMENT OF FATIGUE DURABILITY OF WELDED GUSSET JOINTS BY

CF SHEETS USING VARTM TECHNIQUE

Visal Thay 1, Chang Tan 1, Hitoshi Nakamura 1, Takahiro Matsui 2, Fan Lin 3 1 Tokyo Metropolitan University, Department of Civil and Environmental Engineering, Tokyo, Japan; 2 Toray

Industries, Inc., ACM Technology Department, Tokyo, Japan; 3 Yunnan University, School of Urban Construction and Management, Kunming City, China;


KEYWORDS:

Strengthening and repair; Fatigue; Bond and interfacial stresses; Durability, long-term performance; Vacuum

assisted resin transfer molding technique; Welded joints

ABSTRACT:

Vacuum assisted Resin Transfer Molding (VaRTM) as a composite fabricating technique can be used to apply CF

sheets on cracked steel structures. This paper deals with the fatigue durability of typical welded gusset joints in

steel bridges strengthened by externally bonded CF sheets using VaRTM technique. The strengthened operation

work have been proven to be very efficient and convenient even on complex shapes of structures due to the

flexibility of this method. Perfectly close contact particularly between weld beads and the CF sheets provides a

great advantage on reduction of the high stress concentration which is usually occurred at the fillet weld toe at the

end of gusset plate. The reduction of stress concentration at weld toe was analytical investigated, where the 3D

FEM models were simulated from a number of image data taken from actual experimental specimens by digital

camera. The target specimens of welded gusset plates were fabricated and subjected to cyclic load. The fatigue

tests of two types of specimens, non-strengthened and strengthened specimen using VaRTM technique in the

parameters of number of layers of CF sheets, have been conducted and strengthened effects have been evaluated

under applied stress ranges experimentally. As presented in Figure 1, the result shows that the fatigue durability

of welded gusset joints strengthened by CF sheets using VaRTM technique can be remarkably improved.

Figure 1: Evaluation of Fatigue Durability of Welded Gusset Joints Strengthened by CF Sheets Using VARTM

Technique

105

106

107

50

60

70

80

90

100

200

Number of cycles Nf (cycles)

No

min

al s

tres

s ra

ng

e

sn (

MP

a)

GPC23

sn = 5480.4N−0.285

R=0.94

GPC23_failure

GPC23_limit_ debonding

GPC23_limit

GPN_regression line

120

140

160

180

JSSC_DJSSC_EJSSC_F

GPN

JSSC_C JSSC_B JSSC_A

GPC45_debonding_stop



213


DEVELOPMENT OF A SENSOR FOR MONITORING MECHANICALLY

STRESSED ADHESIVE JOINTS

F. Lehmann1, V. Birtel1, J. Wang1, S. Chataigner2, O. Konrad1 1 MPA University of Stuttgart, Stuttgart, Germany, Email: [email protected]

2 IFSTTAR, MAST Department, SMC Laboratory, Bouguenais, France

KEYWORDS:

Strengthening and repair; Material; Durability, long-term performance; Inspection, NDT methods and quality

assurance

ABSTRACT:

A strengthening System with adhesively bonded CFRP reinforcement was developed in the Infravation

FASSTbridge project to extend the remaining lifetime in fatigue of existing steel bridge constructions. The

premature debonding of CFRP and steel is seen as a major risk to lose the contribution of the retrofitting system.

Therefore, one goal of the FASSTbridge project was to develop a debonding sensor which is integrated into the

strengthening system. Consequently, an ultrathin sensor placed directly in the adhesive layer between steel and

CFRP was developed. It is suited for continuous monitoring of the integrity of the adhesive joint.

The paper explains the underlying physical principles of the sensor and gives insight into the performed tests for

the calibration and verification of its functionality. The sensor conception takes the change of a capacitor’s

electrical impedance as a basis, which occurs when a change in distance between the adjacent conductive faces

takes place. It is well assumed that debonding yields to separation which leads to an increase of the monitored

impedance. The relationship is explored through single lap sheer experiments and vertical tension bond tests. The

sensitivity and the accuracy of the impedance with respect to deformations are revealed by comparing several

groups of prototypes with different dielectric layers and viscous materials. The influences of different temperature

effects and fatigue loadings are also presented

Figure 1: Photos of one of the vertical tension bond test and its results



214


BEHAVIOR OF CONICAL STEEL TANKS STRENGTHENED BY CFRP

Mohamed S. A. Saafan1 1 Ain Shams University, Faculty of Engineering, Structural Engineering Department, Cairo, Egypt

[email protected]

KEYWORDS:

Strengthening and repair; Modeling

ABSTRACT:

Steel tanks are widely used as containment liquid vessels for ground or elevated tank structures. Buckling strength

of conical steel tanks can be reduced by many factors as corrosion especially at the base or by increasing the height

of tank itself. Nowadays, there is an extensive need to increase the storage capacities of elevated tanks. Therefore,

strengthening existing tanks are considered as a solution for upgrading existing water supplying systems to satisfy

the increasing demand of water supply.

Fiber Reinforced Polymer (FRP) are a promising alternative to repair or strengthen structures especially structures

subjected to an aggressive environment or to the effects of electromagnetic fields. FRP has been widely used in

strengthening concrete structures, and research has been extensively covering this area. Many studies for repair

and strengthening of concrete structures using FRP exist. A limited number of experimental and modelling have

been conducted to find the behaviour of FRP / steel systems.

This paper investigates the behaviour of conical tanks strengthened by small-diameter CFRP strands subjected to

hydrostatic pressure.

Three-dimensional numerical models are developed for conical steel tanks using the ANSYS finite element

program. For modelling thin shell structures state of instability under the influence of geometric and material

nonlinearity are included. This model can be used to predict both elastic and inelastic buckling. Due to the

symmetry of the conical tanks in both pressure and geometry, only quarter of the cone is modelled and used in the

analysis.

Ten conical steel tanks are investigated in this analysis with different height, base radius and angle of inclination.

Tanks are assumed to be filled with water. Strengthened tanks with CFRP height 15% of the tank wall length from

the bottom are chosen. This height covers the buckling wave near the bottom of the tank, at which maximum

compressive meridional stresses occurs leading the tank wall to buckle. The CFRP thicknesses are considered as

a percentage from the tank wall thickness.

This study shows that the use of small-diameter CFRP strands to increase the buckling strength of hydrostatically

loaded conical steel tanks is very beneficial. Adding CFRP strands with ratios 10, 20, and 40% of the tank wall

thickness lead to increase of buckling capacity by 34, 47, 64 % and decrease of the meridional displacement at the

bottom of the tank by 17, 22 and 30 %.



215


FINITE ELEMENT ANALYSIS OF STEEL-CFRP BONDED JOINTS WITH

VARIOUS NON-LINEAR TRACTION-SEPARATION LAWS

Vladimir Berka 1, Mina Dawood1 1 University of Houston, Civil and Environmental Engineering Department, Houston, United States of America;


KEYWORDS :

Strengthening and repair; Modeling; Bond and interfacial stresses; Characterization of FRP and FRC

materials/systems; Non-linear adhesives; Parametric Study

ABSTRACT:

This paper presents the findings of a finite element analysis that was conducted to study the effect of various

traction-separation relationships on the behavior of CFRP-steel bonded double-lap shear coupons with thin outer

adherends. The study investigates the influences various shear traction-separation laws have on bond capacity,

bond stresses, and general interface behavior. These simulations provide a first step towards suggesting target

properties for new developments in adhesive technologies. The results may also be used to identify mixed-mode

traction-separation definitions for joints made with poorly characterized adhesives by comparing experimental

behavior to the trends identified by the parametric study. The finite element model was validated by comparison

to previously published double-lap experimental data. The parameters considered in the parametric study include

the characteristics of the peel traction-separation relationship, the shear stiffness, maximum shear strength, and

plastic and softening responses in shear and the fracture energies. The results of the parametric study are compared

to assess the influence of different parameters on the behavior of bonded joints. The results indicate that for

sufficiently low bond lengths bond capacity is influenced most by shear strength. At bond lengths exceeding the

effective bond length, the bond capacity is influenced most by shear toughness. This paper also suggests two

equations for predicting bond capacity as functions of the parameters of a traction-separation formulation at low

and high bond lengths.

(a) Vary Ksoft, df, G (b)Vary Ke, Ksoft, (c) Vary max, Ke, G

(d) Vary df, G (e) Vary max, df, G (f) Vary Ke, max, Ksoft, df

Figure 1: Various shear traction-separation curves studied



216


SHAPE MEMORY ALLOY (SMA) STRIPS FOR FATIGUE STRENGTHENING OF

CRACKED STEEL PLATES

M.R. Izadi 1, 2, E. Ghafoori 1,3, M. Motavalli 1, 2, S. Maalek 2, A. Hosseini 1, 4 1 Empa, Swiss Federal Laboratories for Material Science and Technology, Dübendorf, Switzerland

(corresponding author: [email protected]); 2 University of Tehran, Tehran, Iran;

3 Smart Structures Laboratory, Swinburne University of Technology, Hawthorn VIC 3122, Melbourne, Australia 4 Resilient Steel Structures Laboratory, EPFL, Swiss Federal Institute of Technology Lausanne, Switzerland.

KeyWords:

Iron-based shape memory alloy (Fe-SMA); Steel strengthening; Fatigue; Shape memory effect

(SME); Prestressing.

ABSTRACT:

This paper aims to show the feasibility of application of iron-based shape memory alloy (Fe-SMA) for fatigue

strengthening of steel plates. The effectiveness of the proposed retrofit system was also compared with that of

prestressed carbon-fiber reinforced polymer (CFRP) system. The Fe-SMAs are smart materials that can be self-

prestressed via using their so-called shape memory effect (SME) characteristics. In this study, the Fe-SMA strips

are anchored to the steel plates using a mechanical anchorage system (see Figure 1). The SME in the Fe-SMAs is

activated when the material is heated up to a characteristic temperature. Two precracked steel plates with different

Fe-SMA strengthening schemes were prepared. Additionally, a precracked steel plate without strengthening served

as a reference specimen. Fatigue tests were then performed on the SMA-strengthened steel plates. All specimens

were subjected to a cyclic loading with a stress range of 75 MPa and a load ratio of 0.2. It was observed that the

fatigue life of the steel plates enhanced substantially by using the Fe-SMA strips (see Table 1). The

activated/prestressed Fe-SMA strips apply a compressive stress to the critical cracked detail in the steel plate,

which decreases the tension stress at the crack tip and resulting in an increased fatigue life of the steel plates. The

results of the tests were compared with the existing tests results on CFRP strengthening of steel plates.

Table 1. Specimen description.

Specimens. SMA strip width (mm)1 Strengthening type Schematic cross-sections

S1 N/A Reference, no strengthening

S2 46.7 activated, double-side

S3 105 activated, double-side

1All Fe-SMA strips had a thickness of 1.5 mm.



217


Precracked

steel plate

MTS clip-on

extensometer

Fe-SMA

stripStrain

gauge

Notch

Holes for

clip gage

Figure 1: Fatigue loading test setup.



218


APPLICATION OF PRE-STRESSED UN-BONDED CFRP FOR STRENGTHENING

OF METALLIC STRUCTURES

E. Ghafoori 1,2, A. Hosseini 1, 3, E. Pellissier 4, M. Hueppi 4, M. Motavalli 1, 5 1 Empa, Swiss Federal Laboratories for Material Science and Technology, Dübendorf, Switzerland

(corresponding author: [email protected]); 2 Smart Structures Laboratory, Swinburne University of Technology, Hawthorn VIC 3122, Melbourne, Australia

3 Resilient Steel Structures Laboratory, EPFL, Swiss Federal Institute of Technology Lausanne, Switzerland 4 S&P Clever Reinforcement Company AG, Switzerland;

5 University of Tehran, Tehran, Iran.

KEYWORDS:

Carbon Fiber-reinforced Polymer (CFRP), Steel strengthening, Fatigue, Prestressing, Bonded,

Pre-stressed Un-bonded Reinforcement.

ABSTRACT:

Application of carbon fiber-reinforced polymer (CFRP) composites for retrofitting reinforced concrete structures

has been extensively investigated and used in practice. Many studies demonstrated the beneficial influence of such

composite materials for the flexural and shear strengthening of concrete girders, as well as for confinement of

concrete columns. However, the strengthening techniques and the accompanying theories for metallic structures

have not been developed as thoroughly as those for concrete structures. There are several differences between the

behavior of bonded joints in CFRP-strengthened concrete and metallic members, which will be briefly explained

in this paper. Furthermore, one of the main aims of the paper is to give an overview on different techniques for

carbon-fibre reinforced polymer (CFRP) strengthening of steel plates and beams. Different bonded and un-bonded

retrofit systems will be discussed with particular focus on application of pre-stressed un-bonded retrofit (PUR)

systems. Furthermore, some details about design and testing procedure of a new so called flat PUR (FPUR) system

will be given (see Figure 1.a and 1.b). Finally, the paper gives some details about CFRP strengthening and wireless

sensor monitoring of two old metallic bridges in Switzerland and Australia.

(a) (b)

Figure 1. The FPUR system: (a) installation of the prestressing system and applying the required prestressing

level; (b) fastening the movable clamp and removing the prestressing system.

Connection plate

M12 bolt

M16 rod

120 kN hollow

plunger cylinder

Cylinder

housing




219


INCREASING THE REMAINING FATIGUE SERVICE LIFE OF STEEL

STRUCTURES USING ADHESIVELY BONDED COMPOSITES - DESIGN

APPROACH DEVELOPED IN FASSTBRIDGE

Mazen Wahbeh1, Rami Boundouki1, Mark Weidemueller2, Sylvain Chataigner3, Elena Martín4, Luis Sopeña4 1 Alta Vista Solutions, California, USA; 2 Institution, Leonhardt, Andrä und Partner Beratende Ingenieure VBI

AG (LAP), Berlin, Germany; 3 Institut francais des Sciences et Technologies des Transports, de l'amenagement

et des reseaux (IFSTTAR), Bouguenais, France; 4 Dragados S.A., Madrid, Spain

KEYWORDS :

Strengthening and repair; Experimental study ; Codes, standards and design guidelines; Characterization of FRP


ABSTRACT:

Steel bridges present frequent fatigue problems that reduce their load-carrying capacity and residual life. The

increase of traffic flows and loads in the last decades has enhanced this problem, especially on ageing structures.

The mainstream method to strengthen steel bridges, the attachment of steel plates to the tension flange of the

girders, has several disadvantages: plates are usually bulky, heavy, difficult to fix and prone to corrosion and

fatigue. In general, conventional strengthening techniques are labour intensive and highly disruptive to traffic

flows.

Carbon Fibre Reinforced Polymers (CFRP) composites, though more expensive than steel plates (price per

unit/m2), have relevant advantages for the retrofitting of steel bridges: their application is less time

consuming/traffic disruptive than traditional solutions (i.e. from 1 month to a few days).

The overall objective of FASSTbridge is to develop and demonstrate a reliable preventive, cost-effective and

sustainable solution for steel bridges life-time extension at a pre-failure scenario which enables a drastic reduction

of the economic and environmental costs of ownership of the steel bridges stock in Europe and the USA.

This paper will present the developed assessment tool used to determine the remaining fatigue life of steel

structures. It will then introduce the design of reinforcement in fatigue using adhesively bonded CFRP and the

way to assess the gain in service life using this methodology.



220


SMALL-DIAMETER CFRP SHEAR STRENGTHENING SYSTEM FOR STEEL

BRIDGE GIRDERS

Hamid Kazem1, Ye Zhang 1, Sami Rizkalla 1, Rudolf Seracino 1, Akira Kobayashi2 1North Carolina State University, Department of Civil, Construction and Environmental Engineering, Raleigh,

NC, USA 2Nippon Steel & Sumikin Material Co., Ltd, Composites Company, Japan

(Corresponding Author: Hamid Kazem, Email Address: [email protected])

KEYWORDS:

Strengthening and repair; Experimental study; Bond and interfacial stresses; Small-diameter CFRP; Steel

ABSTRACT:

This paper summarizes the findings of a comprehensive research program, including experimental and analytical

studies undertaken to examine the use of small-diameter Carbon Fiber Reinforced Polymer (CFRP) strands for

shear strengthening of steel structures and bridges. The small-diameter CFRP strands are stitched together with a

gap between the strands to allow each strand to be completely covered by the adhesive material. Most of the current

research findings on the use of CFRP laminate revealed failure due to debonding. However, the small-diameter

CFRP strands have showed high bonding characteristics. The experimental program first examined the proposed

strengthening system to increase the buckling capacity of steel plates. The research then continued to examine the

same strengthening system for increasing the shear capacity of steel plate by subjecting a steel plate to pure shear

loading conditions. The research extended to testing a large-scale beam using the same strengthening system to

verify the performance. The effectiveness of the strengthening system was investigated by varying various

parameters believed to affect the behaviour including different CFRP orientation and reinforcement ratio. Research

findings indicated that the proposed system is effective for shear strengthening of steel structures and the proposed

material used eliminated the typical debonding failure mode, commonly observed for strengthening systems using

CFRP laminates.


Composites


221


BUCKLING BEHAVIOR OF STEEL COLUMNS STRENGTHENED BY PRE-

STRESSED (PS) CFRP LAMINATES

L.L. Hu, P. Feng, H.L. Qiang and Y.C. Zou

Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Department of Civil

Engineering, Tsinghua University, Beijing 100084, China. Email: [email protected].

ABSTRACT

New strengthening method with a novel pre-stressing system, which anchors pre-stressed (PS) CFRP laminates

at the ends of the steel column without a machine (e.g. hydraulic jack), represents promising strengthening

efficiency and convenience. Specifically, the PS CFRP laminates and the pre-stressing system can act as lateral

supports of the long steel column against overall buckling. Based on it, a long steel column strengthened by PS

CFRP laminates and a control specimen are investigated in this study using axial compression tests. As a result,

the buckling load of the strengthened specimen is 2.41 times as that of the un-strengthened specimen, and their

failure mode is overall buckling. The change of convex and concave PS CFRP laminates during loading has also

been obtained, which helps to understand the theory of this strengthening method.


Composites


222


LARGE-SCALE SPACE FRAMES ASSEMBLED USING GFRP COMPOSITES

AND ALUMINUM NODAL JOINTS

Lei Zhang 1, Yu Bai 2, Run Guo 1, and Jiawen Mao 1 1 School of Civil Engineering, Central South University, Changsha, PR China

2 Department of Civil Engineering, Monash University, Melbourne, Australia, Email: [email protected]

KEYWORDS

Fibre reinforced polymer, space frame, aluminum connector, space nodal joint, mechanical performance

ABSTRACT

Glass fibre reinforced polymer (GFRP) composites have superior properties such as light weight and corrosion

resistance. However, they exhibit relative lower elastic modulus, lower shear strength and poor ductility in

comparison to steel. A space frame assembled using GFRP structural members may be a solution, in which the

GFRP members are mainly subjected to axial load rather than shear. Space frame structures can provide acceptable

stiffness at the structural level. Furthermore, the loss of axial stiffness of buckled GFRP members in compression

or the failure of metal connections may provide large nonlinear structural deformation similar as structural

ductility. This paper presents experimental studies on mechanical performances of large-scale space frame

assembled using circular hollow section GFRP composites and aluminum nodal joints. The two ends of the GFRP

members were adhesively bonded with specific aluminum connectors to form one structural member and then such

structural members were interconnected via aluminum space nodal joints by bolted connections. Subsequently, the

built-up space frame (4.80 m length × 4.80 m width × 1.13 m height) was tested in static load and the mechanical

performances were investigated and evaluated. It was found that the proposed space frame structure demonstrated

satisfactory structural stiffness and load carrying capacity and large nonlinear deformation (i.e. overall structural

ductility) through the failure of the aluminum connectors and the space nodal joints.




223


A LIFE CYCLE ANALYSIS APPROACH APPLIED TO THE STRENGTHENING OF

STEEL BRIDGES

A. Orcesi 1, A. Feraille 2 and S. Chataigner 3 1 University Paris-Est, IFSTTAR, MAST EMGCU, Marne la Vallée France. e-mail: [email protected]

2 Université Paris-Est, Laboratoire Navier (UMR 8205), Marne-la-Vallée, France. 3 IFSTTAR, MAST SMC, Allée des Ponts et Chaussées, Nantes, France.

KEYWORDS

Strengthening and repair, CFRP, Life Cycle Cost, Life Cycle Analysis.

ABSTRACT

This paper presents some results obtained in the Infravation research project called “Fast and effective solution

for steel bridges life-time extension” (FASSTbridge). The aim of this project is to develop and demonstrate a

reliable, preventive, cost-effective and sustainable solution for steel bridges fatigue life-time extension.

Original sustainable preventive strengthening techniques will be tested to help postpone difficult, resource-

consuming and costly retrofitting and repair interventions and demolitions of the steel and composite steel bridges

stock. This paper addresses the definition of the needed data and the methodology for the realization of an actual

cost-benefit analysis and a life cycle analysis of the CFRP solution compared with traditional techniques (use of

steel plates) to extend the service life of steel bridges, and considering the economic and environmental profit of

the preventing policy.



224


Strengthening of concrete structures



225


CFRP STRENGTHENING OF BUBBLEDECKS WITH OPENINGS

Nazar Oukaili1 and Hammad Merie 2 1 University of Baghdad, Civil Engineering Department, Baghdad, Iraq; 2 University of Kirkuk, Civil

Engineering Department, Kirkuk, Iraq (corresponding author: [email protected])

KEYWORDS:

Strengthening; Experimental study; Codes, standards and design guidelines; BubbleDeck; Punching shear.

ABSTRACT:

The critical problem in the design of concrete BubbleDeck is the concentration of shear stresses around the column-

slab connection which can cause abrupt punching shear failure at load far below the slab flexural capacity. In

BubbleDeck there is often a need to install new services that required creation of opening in the vicinity of

columns. The existence of the opening take away part of the volume of concrete responsible for resisting shear

forces and unbalanced moments, which in turn further reduces the punching shear capacity of the slab–column

connection. Carbon fiber reinforced polymers (CFRP) have been increasingly studied for their application in the

flexural or shear strengthening of reinforced concrete members due to the substantial increase in strength which

have been achieved. In this study an experimental study for nine two-way BubbleDecks of (2000x2000x230) mm

dimensions with sphere diameter of (180) mm was conducted. The slab is designed as simply supported along four

edges. The main objective of the study is to investigate the punching shear performance of the concrete

BubbleDeck slab with opening which strengthened by CFRP sheets. Parameters which were considered are the

size, position and distance of opening from column and the effective scheme of strengthening with CFRP sheet.

The location of bubbles is inside the critical section, where the critical section is considered to be (2d) from the

face of column according to Euro-Code, where (d) is the effective slab depth. The CFRP sheets were applied

around opening in two layers with width equals to opening dimension (Figure 1). All specimens were subjected to

static point loads which increased monotonically up to failure. The test results showed that, there is an

improvement for the ultimate strength capacity and service load by (22%-30%) compared with the same slabs but

without strengthening. On the other hand, due to increasing the stiffness of member by using CFRP sheets, it was

noticed that at the same load level the value of deflection decreased by (15-25%), the steel strain reduced by (22-

36%) and the concrete compressive strain reduced by (12-20%). Generally, using CFRP sheets for strengthening

BubbleDecks with openings lead to significant improvement of the punching shear capacity

Figure 1: Experimental specimens and strengthening schemes



226


FLEXURAL DEFORMATION CAPACITY OF FRP-CONFINED CONCRETE

COLUMNS

N. Hany 1 and M. Harajli 2

1 American University of Beirut, Department of Civil and Environmental Engineering, Beirut, Lebanon,


2 American University of Beirut, Department of Civil and Environmental Engineering, Beirut, Lebanon.

KEYWORDS

Strengthening and repair, Structure, Seismic applications, FRP jacketing, FRP anchors.

ABSTRACT

Confining concrete columns with external fiber reinforced polymer (FRP) jackets is a widely used technique for

strengthening and repairing existing columns. One important practical application of FRP confinement is in

strengthening the plastic hinge region of reinforced concrete (RC) columns or bridge piers to allow them to sustain

larger lateral load and deformation capacities when subjected to strong earthquake ground motions. This study

focuses on analytical investigation of the flexural deformation of concrete columns when confined externally with

FRP reinforcement. Confinement is provided within the plastic hinge region as either externally-bonded FRP

sheets or as a combination of FRP sheets and transverse FRP anchors. The columns flexural capacity is evaluated

using moment-curvature (M-𝜙) response of the critical column section. The axial compression stress-strain

properties of confined concrete are defined according to an experimentally generated empirical model which was

proposed earlier by the authors accounting for the effect of external FRP sheets and FRP anchors. The effects of

different design parameters on the M-𝜙 response are investigated. These parameters include the confinement

level, presence or absence of FRP anchors, axial load level, and ratio of column longitudinal steel reinforcement.

The results clearly show that confining the plastic hinge region with FRP sheets or with a combination of FRP

sheets and FRP anchors leads to substantial improvement in the M-𝜙 response indicating an improved flexural

deformation capacity of the columns.




227


STOCHASTIC INVERSE APPROACH FOR DURABILITY OF CFRP-CONFINED

CONCRETE

Yongcheng Ji 1, Troy Butler 2 and Yail J. Kim 3 1 Department of Civil Engineering, University of Colorado Denver, USA

2 Department of Mathematical and Statistical Sciences, University of Colorado Denver, USA 3 Department of Civil Engineering, University of Colorado Denver, USA, Email: [email protected]

KEYWORDS

Carbon fiber reinforced polymer (CFRP), confinement, inverse problem, modeling, sulfuric acid, stochastic,

strengthening.

ABSTRACT

This paper presents a two-fold research program to investigate the durability of concrete confined with carbon

fiber reinforced polymer (CFRP) sheets in an acidic environment. The first is concerned with a laboratory

experiment to evaluate the axial behavior of concrete with and without CFRP-confinement subjected to sulfuric

acid (H2SO4 at a 5% concentration) for six weeks. Unconfined concrete cylinders show a marked strength reduction

due to the chemical interaction with H2SO4; however, those with CFRP reveal improved axial responses with a

relatively low strength decrease. The second part of the research focuses on developing a mathematical model to

predict the experimental behavior of the CFRP-confined concrete and on calibrating design parameters in ordinary

and acidic service environments. The model formulation is based on measure theory, which is implemented by a

Python-based simulation program. Test results reveal that sulfuric acid degrades the properties of CFRP. Although

the load-carrying capacity of CFRP-confined concrete is reduced by the acid exposure, the capacity is 423% higher

than that of plain concrete. The empirical constants of ACI440.2R-17 are assessed and a proposal is made to

improve the accuracy of model prediction.



228


AXIAL COMPRESSIVE BEHAVIOUR OF CFFT COLUMNS WITHOUT AND WITH

STEEL FIBRES

Qasim S. Khan 1, Joshua C. Tinker 2, M. Neaz Sheikh 3 and Muhammad N. S. Hadi 3 1 PhD, School of Civil, Mining and Environmental Engineering, University of Wollongong, Australia; Assistant

Professor, Civil Engineering Department, University of Engineering and Technology, Lahore, Pakistan

([email protected]; [email protected]);

2 B.Sc. Student, School of Civil, Mining and Environmental Engineering, University of Wollongong, Australia;

3 Associate Professor, School of Civil, Mining and Environmental Engineering, University of Wollongong,

Australia

ABSTRACT

The Concrete Filled Fibre Reinforced Polymer Tube (CFFT) column has emerged as an attractive practical

substitute of traditional steel bar Reinforced Concrete (RC) column in harsh, aggressive environments where

corrosion of steel reinforcement is the key concern. This experimental study investigates the axial compressive

behaviour of RC columns and CFFT columns without and with steel fibres. A total of six columns of 200 – 206

mm diameter and 800 – 812 mm height including an RC column without steel fibres (SR-0), an RC column

reinforced with 2% by volume of steel fibres (SR-2.0), a Carbon Fibre Reinforced Polymer (CFRP) CFFT column

without steel fibres (CT-0), a CFRP CFFT column reinforced with 2% by volume of steel fibres (CT-2.0), a Glass

Fibre Reinforced Polymer (GFRP) CFFT column without steel fibres (GT-0) and a GFRP CFFT column reinforced

with 2% by volume of steel fibres (GT-2.0). The axial load-axial deformation (P-δ) behaviour of tested columns

showed that CFFT columns without steel fibres carried higher axial loads than RC columns without steel fibres.

Similarly, CFFT columns with steel fibres carried higher axial loads than RC columns with steel fibres due to the

higher circumferential confinement provided by Fibre Reinforced Polymer (FRP) tubes than steel helix. However,

RC columns without and with steel fibres exhibited higher axial deformations than CFFT columns without and

with steel fibres as FRP reinforcement is a linear elastic material and exhibits a brittle failure. The addition of steel

fibres resulted in higher axial loads and higher axial deformations for RC columns with steel fibres than for RC

columns without steel fibres, as steel fibres provided the confinement to the concrete and reduced the crack

propagation in concrete. The CFFT columns with steel fibres exhibited higher axial loads and resulted in a less

brittle failure than CFFT columns without steel fibres. However, the CFFT columns with steel fibres exhibited

lower deformations than CFFT columns without steel fibres.





229


CONFINING CONCRETE COLUMNS WITH BASALT FIBRE TEXTILE

REINFORCED ECC

Y. Zhuge1; A.N. AL-Gemeel1 1 School of Natural and Built Environments, University of South Australia, Adelaide, Australia

KEYWORDS :

Strengthening and repair; Experimental study ; FRC and cement composite materials; Engineering cementitious

composite (ECC); TRM.

ABSTRACT:

Confining concrete structures with fibre reinforced polymer (FRP) is proven to be an efficient technique in

improving the dilation and axial strength of concrete columns. However a few draw backs of using FRP, such as

brittleness of FRP sheet and poor performance of the material at high temperatures, have been found in recently

year. This paper presents a feasibility investigation on a newly developed strengthening system, basalt textile

reinforced engineered cementitious composite (ECC). A combination of basalt textile and ECC was used to

evaluate the effectiveness of this alternative confinement system for concrete columns. The result was compared

with other confinement methods: namely, ECC only and basalt textile reinforced mortar (TRM). All the specimens

were tested under axial load applied on concrete cores to thoroughly create lateral force that could create purely

hoop tensile strength at the confinement layer. The experimental results revealed that the new strengthening system

has significantly enhanced the load carrying capacity and ductility of concrete columns compared to the

unconfined specimens and the TRM technique. The results also showed that ECC itself could be used as a new

retrofitting material in column confinement. It was also found that, in addition to the tensile strength, the

compressive strength of confinement layer could play a major role in confinement effectiveness. A considerable

expansion in vertical direction was observed at mid-height of specimens indicating that the presence of vertical

reinforcement in confinement layer is of interest and should be considered for more effective concrete column

confinement.

(a) basalt grid (b) casting confinement layer



230


(c) demoudling confinement layer

(d) Three segment confinement layer of C-ECC-TB-OS

Figure 1 Specimens application



231


ASSESSMENT OF COMPRESSIVE STRENGTH OF STEEL-REINFORCED

GROUT JACKETED CONCRETE COLUMNS

Georgia E. Thermou1,2, Iman Hajirasouliha1

1The University of Sheffield, Civil and Structural Engineering Department, Sir Frederick Mappin Building

Mappin Street, Sheffield, S1 3JD, UK (corresponding author: [email protected]); 2Aristotle University

of Thessaloniki, Civil Eng. Department, 54124, Thessaloniki, Greece (on leave)

KEYWORDS:

New composite materials, systems and strengthening techniques; Experimental study; Characterization of FRP

and FRC materials/systems; Codes, standards and design guidelines; Steel-Reinforced Grout (SRG);

Strengthening

ABSTRACT:

Steel-Reinforced Grout (SRG) is an innovative composite system for the external repair and strengthening of

existing structures, which comprises Ultra High Tensile Strength Steel (UHTSS) textile embedded in inorganic

mortar matrix. Despite the growing number of SRG strengthening applications in practice, very limited data is

available on the efficiency of this composite system as a jacketing device for concrete confinement. This paper

presents a summary of the experimental work conducted to investigate the efficiency of Steel-Reinforced Grout

(SRG) jacketing at improving the compressive strength of concrete specimens. A wide range of SRG confined

cylindrical specimens were subjected to monotonic concentric uniaxial compression load up to failure. The test

specimens were designed to investigate the effects of different design parameters including the density of the steel

fibre reinforced fabric, the number of fabric layers, the overlap length, the binding mortar and the concrete

compressive strength. The experimental results were then used, by the help of two different statistical indices, to

assess the accuracy of existing Fiber-Reinforcement Cementitious Mortar (FRCM) confinement models from

literature to predict the compressive strength and ultimate strain of the SRG confined columns. A new confinement

model was derived by using best fit linear equations to the data of this study which satisfactorily predicts both

SRG confined strength and ultimate strain.

Figure 1: The SRG jacketing technique



232


STUDY OF RECTANGULAR CONCRETE COLUMNS REINFORCED WITH

EXTERNAL FRP

Ana De Diego1, Sonia Martínez 1, Luis Echevarría 1, José Pedro Gutiérrez1 1 IETCC, CSIC. Eduardo Torroja Institute for Construction Science, Madrid, Spain

KEYWORDS :

Strengthening and repair; Experimental study ; Characterization of FRP and FRC materials/systems; Reinforced

concrete columns; Design models

ABSTRACT:

One of the most attractive applications of FRP is the confinement of concrete columns to enhance both its strength

and ductility against axial compression loads. Concrete confinement can be achieved by bonding layers of FRP

around the column (with the longitudinal fibres oriented perpendicular to the longitudinal axis). So far, many

experimental studies have been conducted on circular cross-sections confined with FRP and subjected to pure axial

compressive loading. Consequently, several design models have been proposed to describe the behaviour of FRP-

confined concrete. There are two key parameters which importantly influence on the fitting of the models: the

strain efficiency factor (the ultimate strain of the FRP jacket is lower than the ultimate strain obtained by the

standard tensile test of the FRP) and the effect of confinement in non-circular sections.

The curvature of the fibres in the jacket has been identified as one of the causes of the reduced value of the effective

ultimate strain, which is particularly predominant in rectangular sections with rounded corners.

Tests on square or rectangular specimens are rather sparse, despite the greater use of these sections in building

structures. These experiments show that the confinement is less effective than in rounded sections.

The aim of this work is to show the results of an experimental program carried out in square and rectangular

specimens in order to define the tensile stress response, strength and ultimate strain of RC columns confined with

FRP composite materials.

This work is part of the Project BIA2016-80310-P, funded by AECI and FEDER, and the Project PIE-201460E049

funded by the Spanish National Research Council. FRP materials were supplied by SIKA, SAU.

Figure 1. Specimen 1_20_1



233


EXPERIMENTAL STUDY OF FRP-CONFINED CONCRETE SUBJECTED TO

PARTIAL UNLOADING AND PARTIAL RELOADING

Pengda Li1, Yufei Wu 1,2, Yingwu Zhou 1, Feng Xing 1 1 Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen China; 2

RMIT University, School of Engineering, Melbourne Australia; (corresponding author: [email protected])

KEYWORDS:

All FRP and smart FRP structures; Modeling ; Seismic applications; Characterization of FRP and FRC

materials/systems

ABSTRACT:

Most cyclic existing stress-strain models for fiber reinforced polymer (FRP) confined concrete are applicable to

complete cyclic loading that means unloading from envelope curve and reloading from zero stress. However,

cyclic model subjected to random partial unloading and reloading patterns are rare due to the lack of sufficient

experiment tests, and the partial cyclic stress-strain relationship is still unclear. In this study, fourteen FRP confined

concrete cylinders were tested under six typical partial cyclic load patterns. The test results indicated that the rule

for partial cyclic stress-strain path are different from that of an envelope cyclic curve, and the determination of

fundamental shape factors such as reloading modulus, plastic strain, and tangent unloading modulus is related to

load history and axial compressive stress. Furthermore, only the effective partial cyclic load history can cause

accumulative damage to concrete in its following cyclic stress-strain path, and these effects are clearly reflected

in the plastic strain and reloading modules. This paper, based on the existing envelope cyclic model, presents a

stress-strain model for FRP confined concrete under random cyclic axial compression, and the proposed model is

applicable for accurately predicting different kinds of partial unloading and partial reloading with good accuracy



234


EXPERIMENTAL STUDY ON CFRP REPAIRING PLAIN CONCRETE

Mariem LIMAIEM1, 2, Elhem GHORBEL 1, Oualid LIMAM 2, Julien MERCIER 3

1 Université Cergy Pontoise Paris Seine, Laboratoire de Mécanique et de Matériaux de Génie Civil, Cergy,

France, [email protected], [email protected] ; 2 Université de Tunis El Manar, École

Nationale d’Ingénieurs de Tunis, Laboratoire de Génie Civil, Tunis, Tunisie, [email protected]; 3

FREYSSINET, France, [email protected]

KEYWORDS

Composite, Carbone, resin, concrete, damage, repairing, modelling.

ABSTRACT

This research, dealt in the framework of the French project ANR MICRO, investigates the effect of concrete

confinement by a commercially available Carbone Fibre woven fabric Reinforced Epoxy Polymer CFRP through

experimental and numerical approaches. Especially, it deals with the repairing of concretes mechanically damaged

at different controlled rates.

The first part of this study is dedicated to the characterization of the epoxy resin, the woven fabric composite used

in the repairing process (mechanical characteristics) and the concrete (compressive and damage behaviours).

The second part is devoted to the experimental study of repaired damaged concrete loaded under compressive and

bending tests. Last part deals with modelling the experimental tests with finite element software CAST3M. The

elasto-plastic model of SELLIER is used for concrete and orthotropic behaviour is adopted for the composite. This

numerical approach considers a perfect adhesion between the composite and concrete.

Experimental results show that confining concrete using CFRP bidirectional 0°- 90° woven fabric allowed

enhancing mechanical performances of the concrete under compression: strength, ductility. Moreover, repairing

mechanically damaged concrete with CFRP can be an efficient solution to restore and even enhance all mechanical

aspects referring to undamaged concretes.







235


MULTI-LAYER TRC-TSR INTERNAL CONFINEMENT FOR HIGH-STRENGTH

CIRCULAR REINFORCED-CONCRETE COLUMNS

Rami Eid, Avraham Cohen, Reuven Guma, Eliav Ifrah, Netanel Levi, Avidor Zvi

Department of Civil Engineering, SCE – Shamoon College of Engineering, Beer Sheva, Israel 84100


KEYWORDS:

Experimental study; FRP internal reinforcement; Codes, standards and design guidelines; High-strength concrete;

Textile-reinforced concrete

ABSTRACT:

The use of high-strength concrete (HSC) is continuously increasing due to its mechanical and durability advantages

over normal-strength concrete (NSC). In high-rise buildings, HSC can reduce the dimensions of the lower-stories

columns, which makes it a more cost-effective choice for builders than NSC. Studies have shown, however, that

HSC is more brittle in compression than NSC and that the confinement provided to HSC is less effective than in

NSC. Therefore, a greater confinement level is required for columns made from higher strength concrete to achieve

similar strength and ductility enhancements. This behaviour is the main obstacle to HSC's widespread use.

Furthermore, the conventional transverse steel reinforcement (TSR) confinement required by the international

standards for HSC columns not designated as part of the seismic-force-resisting system (SFRS) are relatively high.

These requirements results in large amounts of hoops or spirals that are not feasible from construction aspects

especially for large diameter columns typically located at the lower stories of high-rise buildings. This paper

attempts to tackle the latter obstacle and proposes a new construction method using textile-reinforced concrete

(TRC) and conventional transverse steel reinforcement (TSR) as two internal confinement layers. The textile used

is made from unidirectional carbon fibres similar to that used in textile-reinforced mortar (TRM) or fibre-

reinforced polymer (FRP). A test program is designed to examine the axial compressive behaviour of 250 mm

diameter and 750 mm height HSC columns containing dual TRC-TSR internal confinement. Moreover, carbon

FRP tubes were constructed and used as external confinement for several columns to compare with the

conventional (only TSR) and with the new method (TRC-TSR) results. The axial capacity as well as the ductility

behaviour of the tested columns are discussed in the paper. The results of this study (Figure 1) gives an insight on

a new method for constructing HSC columns in high-rise buildings with reduced and therefore more practical

amounts of the TSR compared to those required by the standards.

Figure 1: Axial load versus axial strain for TRC-TSR specimens

0

100

200

300

400

0.00 0.01 0.02 0.03 0.04

Axi

al lo

ad (

ton

)

Axial strain (mm/mm)

S1.4(10-95)T1E

S2.3(12-85)T/F0

S0T3E



236


BEHAVIOUR OF CFRP WRAPPED REINFORCED CONCRETE COLUMNS

UNDER UNIAXIAL COMPRESSION

Asad-ur-Rehman Khan1, Shamsoon Fareed1 1 Department of Civil Engineering, NED University of Engineering and Technology, Karachi, Pakistan

KEYWORDS:

CFRP, Concrete, Confinement, Strengthening, Retroffitting

ABSTRACT:

The structural resistance and stability provided by the supporting columns under different loading conditions plays

a vital role in determining the overall performance of the structure. Thus, any deficiency caused to the columns

may affect the smooth operation of the supporting members and in turn the structure itself, therefore, it is important

that the columns should provide adequate strength (for which it is design) throughout its operational life. However,

it has been observed that due to improper design, alteration in purpose of use of structure (very common in mega

cities) and deficiency caused due to earthquake, blast and impacts in structural members and as a result in the

structure these columns can possibly be subjected to loads which have higher magnitude compared to its design

loads. Due to these deficiencies, columns are retrofitted and/or strengthened in order to ensure that the structure

can provide a certain level of resilience under different loading conditions during its design life. In this study, an

experimental investigation was carried out to assess the behaviour of CFRP wrapped reinforced concrete columns

under uniaxial compressive loads. For this purpose, ten specimens having rectangular cross-section of 6//×12// and

a height of 24// were tested. The specimens having nominal compressive strength of 21 MPa (typically used

concrete strength in construction industry of Pakistan) and reinforced with both longitudinal and transverse

reinforcement were investigated. These specimens were wrapped with three different CFRP wrapping techniques

which include: (i) wrapped along the full height of the specimen, (ii) wrapped along the two-third height of the

specimen and (iii) strip wrapping along the full height. Based on the experimental investigation carried in this

study, it was found that the reinforced concrete specimens fully wrapped with CFRP exhibited higher peak load

values as compared to other specimens and specimen failed due to the CFRP rupture and the crushing of concrete

cover.



237


AXIAL COMPRESSIVE BEHAVIOUR OF HYBRID FRP CONFINED CONCRETE

Filipe Ribeiro1, José Sena-Cruz 2, Eduardo Júlio 1, Fernando Branco 3 1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Portugal; 2 ISISE, Department of Civil

Engineering, University of Minho, Portugal; 3 ISISE, Department of Civil Engineering, University of Coimbra,

Coimbra, Portugal (corresponding author: [email protected])

KEYWORDS:

New composite materials, systems and strengthening techniques; hybrid effect, pseudo-ductility, confinement

ABSTRACT:

Fibre Reinforced Polymers (FRP) composites can be effectively used as passive confinement system of concrete

columns. Regarding to this option, however, two main drawbacks can be pointed out: (i) in several cases the

ultimate lateral strain in the confinement is significantly lower than the tensile strain at failure of the composite,

and (ii) the conventional composites experience brittle failure, in an explosive manner in the case of confined

concrete without warning which, associated with insufficient residual integrity, requires conservative design.

In this context, unidirectional hybrid FRP composites can be seen as an alternative to traditional FRP composites,

since they present pseudo-ductile tensile response - a mechanical non-linear behaviour characterized by flat-topped

tensile stress strain curve. However, none of the constituents of the hybrid composites show plastic deformation.

Usually, hybrid FRP composites consist of two types of fibres, namely low strain (LS) and high strain (HS) fibres,

within the same polymeric matrix. In addition to pseudo-ductility, hybridisation, promotes synergies between the

involved reinforcing materials conducting to the increase of the apparent failure strain of LS fibres. This increase

in the strain of LS fibres can goes up to 50%, e.g. (Ribeiro et al. 2018, Swolfs, Gorbatikh and Verpoest 2014)),

being described in the literature as “hybrid effect”.

The aim of this research is to assess the performance of 10 different unidirectional (UD) interlayer hybrid

composite combinations on the confinement of small-scale plain concrete columns, exploiting the hybrid effect

and pseudo-ductility provided by these materials. It is demonstrated that hybrid effect can maximize the lateral

strain efficiency of FRP. Furthermore, an analysis-oriented model is developed to hybrid FRP-confined concrete

by modifying the calculation method of the confining pressure in the analysis-oriented model presented in

bibliography.

In the present work, a total of 30 hybrid FRP-confined specimens were prepared and tested under monotonic

uniaxial compression. Each specimen was 150 mm in diameter and 300 mm in height, as shown in Figure 1.

Symmetrical hybrid FRP combinations of 3 and 5 layers were applied as confining material. Different

combinations of the following dry unidirectional fabric materials were adopted in materialization of confining

systems of concrete cylinders under axial loading: high-modulus carbon (CHM), standard carbon (C) and E-glass

(G).




238


(a) (b) (c) (d)

Figure 6: Axial compressive test: (a) illustration of the test; (b) geometry of specimen (dimensions in mm);

(c) layers position, LVDT and strain gauge arrangement for confining systems with 3 layers and (d) layers

position, LVDT and strain gauge arrangement for confining systems with 5 layers.

In general, the relationship between and uniaxial strain and stress follows approximately a bilinear law, where the

slope of the first branch primarily depends on the properties of plain concrete, whereas the slope of the hardening

branch is determined by the confining pressures induce by the confining system. This initial phase is similar for

all the combinations. From approximately the point corresponding to the theoretical peak of plain concrete (fc0,

εc0). The different applied confining materials induce different confining pressures which leads to FRP-confined

concretes exhibit different trends after fc0, εc0 point. In two cases, in which pseudo-ductile behaviour of the hybrid

FRP occurred (2G/1CHM/G and 1G/1CHM/1G) a flat-topped stress-strain curve is observed, as shown in Figure

2. In the same figure the number before letters in series ID shows the number of layers.

(a) (b)

Figure 7: Stress–strain curves of CHM/G combinations: experimental versus predicted values: (a)

2G/1CHM/2G and (b) 1G/1CHM/1G.

Specimen

Straingauges

LV

DT

1

LV

DT

3

Steel disc

Specimen

concrete

hybrid

composite300

150

150 mm

overlap

SG2

SG3

SG1

LVDT2

LVDT1

LVDT3

LVDT2

LVDT1

LVDT3

SG1

SG2

SG3

SG4

SG5

150 mm

overlap



239


A STUDY ON FRP-CONFINED CONCRETE IN PRESENCE OF DIFFERENT PRE-

LOAD LEVELS

Francesco Micelli 1, Alessio Cascardi 1, Maria Antonietta Aiello 1 1 University of Salento, Department of Innovation Engineering, Lecce – Italy

KEYWORDS

Strengthening and repair; Confinement; Experimental study; Concrete; FRP.

ABSTRACT

The application of external confinement of concrete columns by using Fiber Reinforced Polymers (FRPs)

composites has been widely studied and recognized as an effective technology. The most part of the experimental

studies that were conducted are related to columns that were confined without a pre-loading condition, which is

the most common situation that is met in the field. In order to increase the knowledge, this research illustrates and

discusses the experimental results that were obtained by testing concrete cylinders that were confined with Carbon

FRP (CFRP) unidirectional sheets at five different pre-loading levels. The concrete cylinders were prepared and

poured at the same time in order to minimize difference in the starting properties of the concrete core. Five

specimens were prepared for each pre-load level. Thus, 25 concrete specimens having a diameter of 100 mm

diameter and height of 200 mm have been tested. In detail, 5 coupons were unconfined (“U”); 5 were CFRP-

confined with null pre-load level (“P0”); and three sets of 5 specimens, named “P20”, “P50” and “P80”, were

FRP-confined during the application of a pre-load level equal to 20%, 50% and 80% of the ultimate unconfined

concrete compressive strength, respectively.

The experimental results revealed the different mechanical response depending of the pre-damage state of the

cylinders corresponding to different pre-load levels. Until a pre-load level of 20% the effects can be considered

almost negligible, while for higher pre-load levels (50% and 80%) it is remarkable to consider the loss of

mechanical properties respect to an ideal un-loaded configuration. The paper will discuss all the aspects related to

the experimental results, also showing an analytical procedure to take into account the effects of the pre-loading

conditions.

Figure 1: Detail of the specimens after testing: P0, P20, P50 and P80 from top to bottom.



240


MINERAL COMPOSITE AS A SUSTAINABLE BONDING ALTERNATE TO

BENEFIT CFRP RETROFIT

Raghavendra Vasudeva Upadhyaya1, T.G. Suntharavadivel2, Kai Duan3 1 CQ University, Department of Civil Engineering, Rockhampton, Australia; 2 CQ University, Department of Civil Engineering, Rockhampton, Australia; 3 CQ University, Department of Civil Engineering, Rockhampton, Australia

KEYWORDS:

Strengthening and repair; Experimental study ; FRC and cement composite materials; Eco-composite & bio-

sourced composite materials ; rehabilitation of damaged concrete; Mineral based composites.

ABSTRACT:

Structural strengthening for damaged concrete structures is a growing concern for the last few decades as

demolition and re-construction involve huge monetary investments and time concerns. In some cases, it may not

even be necessary as the operational life of a structure may be extended by various other rehabilitation procedures.

This paper deals with the experimental evaluation of carbon and glass fibre retrofit methods applied to various

levels of concrete damage using an alternative sustainable bonder. Fibre Reinforced Polymer (FRP) retrofit is a

popular rehabilitation technique that can increase the life expectancy of any structure by providing additional

strength to the damaged concrete section. The conventional way of imposing the fibre sheet to the structure is by

using epoxy resin as a bonding agent. Few scientists have studied the effects if epoxy on human intervention and

found to have severe health impacts. Literature study suggests a few drawbacks of working with epoxy and impacts

due to toxic emissions from the resin at high temperatures. It is time, that the world is switching over to

sustainability and engineering scholars are working on a special admixture that could possibly replace epoxy.

Mineral based bonding admixture is a recent development and found to be performing well for FRP retrofits. The

main objective of this study is to develop a mineral admixture that could behave similar to epoxy but sustainable

enough. Therefore, the mechanical properties of cement-based bonder that has been presented in the study are

compared to that of epoxy. Moreover, two different FRP materials have also been subjected to analysis to compare

and contrast the suitability of mineral bonder. The standard error calculation at the end of experimental

investigation provides us with the necessary range of accuracy over various levels of induced damaged in the tested

specimens. It was clearly distinguished that mineral based admixture performs slightly better than harmful epoxy

as the probability of failure accumulates and is definitely a possible FRP bonding replacement.

Figure 1 : Type of failure in epoxy and MBC retrofitted CFRP specimens



241


BEHAVIOUR OF CFRP CONFINED RC SQUARE COLUMNS UNDER ECCENTRIC

COMPRESSIVE LOADING

Faiz U.A. Shaikh*, Reza Alishahi and Prabir K. Sarker

School of Civil and Mechanical engineering, Curtin University, GPO Box: U1987, Perth, WA6845, Australia.

(*Corresponding author Email: [email protected])

KEYWORDS:

CFRP, Columns, eccentricity, strengthening, failure behaviour, compression load.

ABSTRACT:

A considerable number of reinforced concrete columns in various structures are square or rectangular cross

sections and also undergoes eccentric compressive loading condition during their service life. This type of loading

could emerge due to various reasons including construction error, etc. Lots of studies present the behaviour of

carbon fibre reinforced polymer (CFRP) confined RC columns under concentric loading where most of the

columns are of circular cross-section. Considering the fact that there are few experimental studies in the literature

on the behaviour of reinforced concrete columns with square cross section under eccentric static loading

conditions; this study evaluates the behaviour of such CFRP confined columns under different eccentricities. In

total 14 columns are tested. Dimensions of all columns are 175x175x800 mm with 20mm rounded corners.

Parameters considered in this study are number of CFRP layers (e.g. 1, 2 and 3 layers) and eccentricities (e.g. 25,

35 and 50mm) of the applied Load. Behaviour of columns are reported based on load carrying capacity, axial

strain, hoop strain and lateral deflection that they endured. Results indicate that eccentrically loaded CFRP

confined columns could undergo higher loads and higher ductility compared to reference columns.



242


COMPRESSIVE BEHAVIOR OF CONCRETE COLUMNS AXIALLY-LOADED

BEFORE CFRP-WRAPPING. REMARKS BY EXPERIMENTAL-NUMERICAL

INVESTIGATION.

Marco Filippo Ferrotto1, Oliver Fischer2, Roland Niedermeier2, Liborio Cavaleri1 1 University of Palermo, Department of Civil, Environmental, Aerospace, Material Engineering, Palermo, Italy ; 2 Technical University of Munich, Department of Civil, Geo and Environmental Engineering, Munich, Germany;


KEYWORDS

Strengthening and repair; Characterization of FRP and FRC materials/systems; Experimental study; Modeling;

ABSTRACT:

Strengthening of existing concrete columns with Fiber Reinforced Polymers (FRP) results generally in a

satisfactory structural member improvement in terms of load and strain capacity. A reliable prediction of the

capacity obtained by these reinforcement strategies requests a proper knowledge of the load-strain response of the

confined concrete elements. However, so far, the available design methods and technical codes do not consider

the effect of the possible presence of service loads at the moment of application of the reinforcement, and therefore,

the compressive behavior of the concrete confined under preload is still unclear.

In this paper, the effect of sustained loads on the compressive behavior of concrete columns CFRP-confined while

preloaded is analyzed. Experimental tests were performed on circular concrete columns confined under low,

medium and high preload levels before wrapping ad subsequently loaded until failure, observing the differences

respect to the standard compressive stress-strain response of FRP-confined concrete. A finite element (FE) model

is also developed by using ABAQUS software to simulate the physical scheme of the experimental tests. The

accuracy of the model is validated through comparing with the experimental results.



243


STUB COLUMN TESTS OF FRP-CONFINED RUBBER CONCRETE WITH

VARIOUS REPLACEMENT RATIOS

Chun-Wa Chan1, Shi-Shun Zhang2, Tao Yu3

1 School of Civil, Mining and Environmental Engineering, Faculty of Engineering and Information Sciences,

University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia 2 School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan, Hubei,

China, 430074

([email protected]) 3 School of Civil, Mining and Environmental Engineering, Faculty of Engineering and Information Sciences,

University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia

([email protected])

KEYWORDS

Waste tyre; Rubber particle; rubber concrete; FRP; confinement

ABSTRACT

The practical application of rubber concrete has so far been mainly limited to non-structural use due to its

disadvantages induced by the rubber particles, such as the relatively low compressive strength and early cracking.

One effective way to overcome the detrimental effects of these disadvantages is to use fibre reinforced polymer

(FRP) as an external confining device to confine the concrete. In this paper, results from a series of stub column

tests on FRP-confined rubber concrete with various replacement ratios are presented. The test results confirmed

that the FRP confinement is effective in improving the strength and ductility of rubber concrete, and that the

replacement ratio has a smaller effect on the strength of FRP-confined concrete than on the unconfined concrete.



244


BEHAVIOUR OF FRP-CONFINED RUBBERISED CONCRETE: AN

EXPERIMENTAL INVESTIGATION

Samar Raffoul 1, Reyes Garcia 1, David Escolano-Margarit 1, Maurizio Guadagnini 1, Iman Hajirasouliha 1,

Kypros Pilakoutas 1 1 Dept. of Civil and Structural Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin

Street, Sheffield S1 3JD, UK (corresponding author: [email protected])

KEYWORDS :

New composite materials, systems and strengthening techniques; Experimental study ; Seismic applications;

Characterization of FRP and FRC materials/systems

ABSTRACT:

An estimated one billion tyres are discarded every year after reaching their service life. Many of such tyres are

disposed of in landfills or incinerated as fuel, causing health, environmental and economic hazards. To reduce

these hazards, previous research has investigated the use of end-of-life tyre rubber to partially replace concrete

aggregates. Compared to conventional concrete, rubberised concrete is less workable and has lower compressive

strength, and it is therefore mainly used in non-structural/low-strength applications. Nonetheless, recycled tyre

rubber can offer excellent strength, durability and flexibility that could be exploited in different construction

applications. To examine the potential use of high rubber contents of tyre rubber in concrete, the Anagennisi

project developed innovative concrete applications with reduced environmental impact.

This paper examines the use of externally bonded Fibre Reinforced Polymer (FRP) jackets to develop a novel

highly-deformable FRP Confined Rubberised Concrete (FRP CRuC), see Figure 1. Sixty rubberised concrete

(RuC) cylinders were tested in axial compression. The cylinders were produced using recycled tyre rubber to

replace i) 0–100% fine or coarse aggregate volume or ii) a replacement of 40% or 60% of the total aggregate

volume. Six cylinders of the latter mix were then confined with two or three layers of Aramid FRP sheets. The

results indicate that the use of high rubber contents in concrete lead to premature microcracking and lateral

expansion, the latter of which can be used to activate the FRP confinement earlier and achieve higher confinement

effectiveness. The FRP CRuC cylinders reached compressive strengths of up to 75.0 MPa and ultimate axial strains

up to 5%, i.e. about fourteen times larger than those of normal concrete (0.35%). Such novel high-strength, highly-

deformable CRuC is of great value to engineers and can be used for structural applications where large

deformability is required, such as plastic hinges of bridges and buildings located in seismic zones.

Figure 1 : AFRP CRuC during testing



245


RETROFITTING OF BRIDGE GIRDER WITH CFRP

Anees Muhammad1, Samiullah Qazi 2 1,2 University of Engineering and Technology, CIVIL Engineering Department, Peshawar and Pakistan;


KEYWORDS:

Strengthening and repair; Experimental study ; Seismic applications; Bond and interfacial stresses , RC Bridge

Girder, FRP Anchorage

ABSTRACT:

Bridges are considered as the life line and key element in transportation system. Main components of typical bridge

are Pile, Pile cape, Piers, Transom, Girder and slab Deck. Bridges collapse occur due to failure of these components

individually or simultaneously. Its susceptible to failure due to flaws in design or construction. To overcome these

deficiencies and improve structure performance strengthening or retrofitting of partially damaged bridges is

required. Therefor in this research work the CFRP external strengthening/retrofitting techniques will be

implemented to improve the performance of Bridge girders. As the CFRP strengthening technique applied in the

form of wrapping CFRP sheets around structural members reduce the member energy dissipation capacity

therefore in this case the bonding technique will be implemented. However, whenever this technique is

implemented the strengthen specimen fail due to delamination issue at the Concrete/CFRP interface. Research

work have highlighted that the delamination issue limits the CFRP efficiency and only 50% of its tensile strength

could be utilized. To limit this problem a novel anchorage technique will be tested in this research work. In this

research in total five T shape bridge girders model at 1:4 scale will be subjected to quasi static load test. Out of

these five one will be tested as control, two strengthened and four will be retrofitted (including control specimen).

The test results discussion includes hysteresis curves, energy dissipation and damage performance index.

Figure 8:CFRP reinforcement details



246


DEVELOPMENT OF DESIGN GUIDELINES FOR BEAMS PRESTRESSED

WITH CFRP SYSTEMS

A. Belarbi 1, H. Tahsiri1, P. Poudel1, M. Reda1, M. Dawood1, and B. Gencturk 2

1University of Houston, Dept of Civil and Environmental Engineering, Houston, TX, USA,


2University of Southern California, Sonny Astani Dept of Civil and Environmental Engineering,

Los Angeles, CA, USA

KEYWORDS :

All FRP and smart FRP structures; Standard ; Prestressing with FRP composites; Codes, standards and design

guidelines ; Prestress losses

ABSTRACT:

Advancement in material science has enabled engineers to enhance the strength and long-term behavior of concrete

structures. The conventional approach is to use steel for prestressed bridge girders. Despite having sufficient

ductility and strength, beams prestressed with steel are susceptible to corrosion when subjected to environmental

exposure. The corrosion of the prestressing steel reduces load carrying capacity of the prestressed member and can

result in catastrophic failures. In the last three decades, more durable composite materials such as Aramid Fiber

Reinforced Polymer (AFRP), Glass Fiber Reinforced Polymer (GFRP) and Carbon Fiber Reinforced Polymer

(CFRP) have been implemented in concrete structures as a solution for this issue. Among these materials, CFRP

tendons stand out as a primary prestressing reinforcement, which has the potential to replace steel and provide

corrosion free prestressed bridge girders. In the United States, CFRP prestressing systems have had limited

application in bridge construction due to the lack of nationally accepted design specifications. Further investigation

is required to review available information and develop a proposed guide specification, in AASHTO LRFD format,

for the design of concrete bridge beams prestressed with CFRP systems. A National Co-operative Highway

Research Program (NCHRP) project titled ‘Guide Specification for the Design of Concrete Bridge Beams

Prestressed with CFRP Systems’ was carried out at University of Houston. This paper presents the results from

the experimental and analytical research performed on short-term behavior of CFRP (tensile test, harping test),

long-term behavior of CFRP (prestress relaxation and, concrete creep and shrinkage losses) and the flexural

behavior of the full-scale bridge beams prestressed with CFRP systems.



247


QUANTITATIVE APPROACH TO ANCHORING SPIKES DESIGN IN FLEXURAL

APPLICATIONS

Marco Rossini1, Antonio Nanni 1, Carlo Poggi 2 1 University of Miami, Department of Civil Arch. and Environ. Engineering, Coral Gables, FL, USA.

2 Politecnico di Milano, Department of Arch. Build Environ. and Construction Engineering, Milano, Italy.

(Marco Rossini: [email protected])

KEYWORDS :

Strengthening and repair; Experimental study; Bond and interfacial stresses; Codes, standards and design

guidelines; Anchoring Spikes;

ABSTRACT:

Research into fiber reinforced polymers (FRP) for strengthening applications has an established tradition.

Confidence in deploying the technology has increased over the years, and reliable design procedures are available

(CNR, 2014; ACI, 2008). Nonetheless, areas of improvements still exist and require further investigation.

Premature failure due to debonding is identified as a major limitation to the efficiency and ductility of externally

bonded FRP strips (EB-FRP). A solution consists in mechanically anchoring the composite sheet to the concrete

substrate, and spikes (Figure 1) represent a common anchoring solution.

A quantitative approach to characterization and design of anchoring solutions is still at its early stage of

development. An accepted strength characterization method for single anchors and coupled joints is missing, along

with the definition and validation of design algorithms for flexural applications. The research presented in the

following, focusing on anchoring spikes, lays within a comprehensive effort to address such challenges for a wider

range of traditional and innovative anchoring shapes.

A possible solution to the design problem is proposed in terms of a simplified algorithm. The proposed algorithm

is validated on a small number of anchored slabs, flexural tested in a three-point-bending configuration. The slabs’

behavior is discussed, and consistency with the proposed model is detailed. The proposed model features good

experimental matching in the cases considered. Experimental validation over a larger dataset is beyond the

purposes of this study, and shall be performed before application to real-case design.

Figure 9: Anchor spikes on one of the tested slabs after failure.




248


FRACTURE MECHANICS BASED CALCULATION MODEL OF FLEXED RC

ELEMENTS STRENGTHENED WITH FRP

Justas Slaitas1, Juozas Valivonis1 1 Vilnius Gediminas Technical University, Department of Reinforced Concrete Structures and Geotechnics,

Vilnius, Lithuania (corresponding author: [email protected])

KEYWORDS :

Strengthening and repair; Case studies; Codes, standards and design guidelines; Bond and interfacial stresses

ABSTRACT:

Retrofitting of existing reinforced concrete structures is one of the main challenges for civil/construction engineers

today. The use of FRP materials for these purpose has many advantages in comparison to the traditional

strengthening materials such as concrete jackets, steel plates, etc. However, the effectiveness of the strengthening

can be compromised by sudden and brittle FRP debonding failure modes, which can occur at lower load than 60%

of calculated elements flexural strength. In this paper calculation model of RC structures strengthened with

prestressed and not prestressed various EB and NSM FRP reinforcements have been presented. Proposed model

is based on the theory of fracture mechanics of solids. The science of fracture mechanics could be used for the

analysis of the fracture development in flexural reinforced concrete beams. The critical parameters of normal

cracks caused by stress state are used for such analysis. For calculation of FRP strengthened structures, fracture

mechanics based calculation models for RC structures were combined with built up bars theory, which served well

for reducing elements stiffness because of slip between concrete and FRP. Therefore, here proposed calculation

model allows to predict the failure of strengthened RC elements even for sudden and brittle FRP debonding failure

modes.

Experimental results of various scientific publications have shown that load – deflection dependency graph is

similar to trilinear (see Figure 1), thus bending moments are determined at three main points: cracking of concrete;

yielding of tension steel; failure of beam.

Figure 1: Load-deflection dependency graph

The numerical results are compared with experimental ones. 71 RC beams, strengthened with CFRP and GFRP

sheets, plates, strips and rods, mounted by EBR or NSM methods, are analysed in this comparison. Experimental

results were collected from various scientific publications.



249


EXPERIMENTAL AND FINITE ELEMENT STUDY ON RC BEAMS RETROFITTED

WITH FULL-LENGTH AND SPLICED FRP LAMINATES

Akram Jawdhari 1, Issam Harik 1 1 University of Kentucky, Department of Civil Engineering, Lexington, Kentucky

KEYWORDS:

RC members; Strengthening; FRP laminate; FRP splice; Debonding; Finite element; Bond-slip model.

ABSTRACT:

Fiber reinforced polymer (FRPs) composites such as laminates, fabrics, bars, etc., have gained world-wide

recognition and became a normal choice for reinforcing, repairing, and strengthening concrete structures. This is

due to the superior characteristics FRP carries such as high tensile strength and stiffness, light weight and ease of

handling and installation. However, retrofit of members with long-span or with limited accessibility (e.g. bridges

over waterways and freeways) using continuous FRPs requires extensive labour and equipment. Splicing the

laminate could provide an economical solution by reducing the cost of installation. This study consists of

experimental testing of three full-scale RC beams subjected to four-point bending static loads. One beam served

as a control specimen, while two beams were strengthened with Carbon FRP (CFRP) laminates (one beam by full-

length laminate and the other by two half-length laminates made continuous with a splice). The control beam failed

in the typical mode for under-reinforced concrete members (by yielding of steel in tension followed by crushing

of concrete in compression), at a maximum load of 18.4 kN. The strengthened beams failed by debonding, at the

laminate ends for full-length laminate and at splice ends for the spliced laminate. The maximum load for

strengthened beams is: 27.3 kN (or 49% increase from the control beam) for the full-length laminate; and 24.2 kN

(or 31.8% increase) for the spliced laminate. In addition, three-dimensional finite element models were developed

for the beams to complement the testing and to provide an in-depth analysis including the simulation of debonding

failure. Comparisons with the experiments, in terms of maximum load, load-deflection history and prediction of

failure have confirmed the validity of the models and provided an excellent platform for future parametric studies

intended to better design the spliced laminate system and reduce the likelihood of debonding.



250


EXPERIMENTAL AND NUMERICAL ANALYSIS OF STRENGTHENED SHORT

REINFORCED CONCRETE CORBEL BONDED BY CFRP2 UNDER CYCLIC

LOADS

Jules Assih1, Ivelina Ivanova1,2, Veselin Stankov1,2 Dimitar Dontchev2

1 University of Reims Champagne-Ardenne, Department of Civil Engineering, Reims, France 2 University of Chemical Technology and Metallurgy, Department of Applied Mechanic, Sofia, Bulgaria

KEYWORDS:

Strengthening and repair; Fatigue; Characterization of FRP and FRC materials/systems; Modeling ;

Experimental study;

ABSTRACT:

This paper focuses on experimental and numerical modelling of strengthened reinforced concrete corbels with

carbon fibre reinforced polymer (CFRP) under fatigue test. In fact, fatigue is a process in which the action of

stresses or strains in varying time changes the local properties of the materials and can lead to the cracking and

eventually the collapse of structure. Experimentally, four reinforced concrete (RC) corbels are made and two of

them are strengthened by wrapping with CFRP. One unstrengthened RC corbel and another strengthened one are

subjected to a single bending load and the other two are cyclically loaded in fatigue test to one million cycles. The

load values corresponded from 20 % to 40 % of ultimate tensile strength. The shape of applied load was a triangular

wave. The bounds of repeated loads were 71 kN to 130 kN for unstrengthened corbel, respectively and 143 kN to

260 kN for strengthened corbel. The examined effects were the damage development, the ultimate loads, the

influence of fatigue, the state of cracking and the types of failures. In fact, the results showed that the cyclic loading

of one million cycles modified the cracking state of the structures. Additionally, the strengthening by wrapping

delays the cracks appearance with a reduction of ultimate loads from 10% to 15%. The numerical simulations

described in this paper, using Finite element method of ABAQUS software, model the behaviour of fatigue. Of

course, a bending crack was introduced in the model before a series of repeated loadings up to one million cycles.

The numerical model response is compared with experimental test results and yielded good agreement at all stages

of loading. The objective of numerical investigation was to contribute to increase the lifetime of reinforced

concrete structures, to reduce the expensive cost and the difficult implementation of experimental tests.

2 Carbon Fiber Reinforced Polymer



251


REHABILITATION OF REINFORCED CONCRETE STRUCTURES BY FRP AND

WOOD

Cecile GRAZIDE*, Emmanuel FERRIER, Laurent MICHEL Université Lyon 1, Domaine Scientifique La Doua, EA 7427,

Laboratoire des Matériaux Composites pour la Construction (LMC²),

82 Boulevard Niels Bohr,

69622 Villeurbanne Cedex, France

*Corresponding author: [email protected]

KEYWORDS :

Reinforced concrete; lumber ; Fiber Reinforced Polymer; bending behaviour

ABSTRACT:

The durability of concrete structure may be limited by poor-quality construction materials, conception, inadequate

design codes or corrosive environments. Strengthening and rehabilitation of these structures, often expensive, are

then necessary to reinforce, control/decrease the cracking process. To minimise refection costs, a partial wrapping

with Carbon or Glass Fiber-Reinforced-Polymer (CFRP or GFRP) is used in construction.

However, these kinds of punctual reinforcement show disadvantages like the risk of developing cracks on the

remaining structure and a lower fire resistance.

To avoid these two aspects, 9 reinforced concrete beams with continuous reinforcement in wood/ FRP were

manufactured. The aim was to study the effect of this process on the bending behaviour. Dimensions of concrete

elements (150x250x3000 mm3) and the steel ratio (As = 0.004Ac) were fixed and only the kind of reinforcement

was studied. 7 beams were reinforced by lumber element with a cross-section of 45x90 mm² (including 5 with

FRP bars) and 2 beams with only lumber element of cross-section 25x90mm².

Indeed, to evaluate the effect of composite and lumber on the structural element, CFRP and GFRP bars were

anchored in lumber 45x90 mm². 2 beams were realized with GFRP bar with a diameter of 14 mm, 2 others beams

with CFRP bar with a diameter of 9 mm and another one with GFRP bar of 9 mm. The two last beams are only

composed of concrete and lumber.

Four points bending tests were realized and loads and displacements at mid-span were then recorded. In term of

ultimate state design, maximum loads are equivalent except for the 2 beams with lumber elements of 25x90 mm²,

because of the failure mode and the variability of the material. Nevertheless, the stiffness of beams with FRP bars

are significantly higher, which is interesting for the serviceability limit state and the verification of the deflection.

Figure 1 : Applied Load vs Deflection of beams




252


FLEXURAL BEHAVIOUR OF SRG STRENGTHENED REINFORCED CONCRETE

BEAMS

Luciano Ombres 1; Salvatore Verre2 1Department of Civil Engineering, University of Calabria, Arcavacata di Rende (CS) Italy; (corresponding

author, [email protected]) 2 Department of Civil Engineering, University of Calabria, Arcavacata di Rende (CS), Italy

KEYWORDS :

SRG, reinforced concrete, beams, anchors

ABSTRACT:

As well-known, the use of composite materials is becoming very widespread for rehabilitate or strengthen existing

structures. In this field there is a growing interest towards developing high performance, durable and cost effective

solutions. The successful experience on Fiber Reinforced Polymer (FRP) and Fabric Reinforced Cementitious

Matrix (FRCM) composites led to introduction of a new material system that shares the same technology with

FRCM, except that the fabric consists of steel fibres instead of carbon, PBO, glass or basalt ones. The new system

commercially known as Steel Reinforced Grout (SRG) uses galvanized high strength steel wires that are twisted

together to form cords and assembled in form of unidirectional fabrics. By the use of its inorganic matrix, the SRG

is expected overcome some drawbacks of FRP due to the presence of organic matrix. The effectiveness of the SRG

system as strengthening systems of reinforced concrete structures has been investigated by some experimental

tests on both beams strengthened in flexure and shear and confined concrete columns. Even if obtained results are

significant, the number of tests is limited and some aspects of the mechanical behaviour of strengthened elements

have to be well clarified.

This paper presents the results of an experimental investigation of the flexural response of reinforced concrete

(RC) beams strengthened using externally bonded steel fiber reinforced cementitious matrix (SRG) composite.

Four reinforced concrete beams were tested; one beam was un-strengthened while the remaining beams were

strengthened with a single layer of SRG bonded to the tension face with or without the use of mechanical anchors.

Tests results in terms of failure modes, failure load, load- deflection curves, strain and stress distributions and

ductility, presented and discussed in the paper, evidenced the effectiveness of the SRG composites as strengthening

systems of existing reinforced concrete structures.



253


INTERFACIAL BOND DEGRADATION OF FRP STRENGTHENED RC BEAMS

SUBJECTED TO FREEZE-THAW CYCLES

Jiawei Shi1, Zhishen Wu 2 1 College of Civil and Transportation Engineering, Hohai University, Nanjing, China, Email: [email protected]

2 International Institute for Urban Systems Engineering, Southeast University, Nanjing, China.

KEYWORDS :

Strengthening and repair; Modeling ; Durability, long-term performance; Bond and interfacial stresses

ABSTRACT: Freeze-thaw (FT) cycling is one of the environmental threats for the durability of concrete structures

in cold regions. When FRP laminates are applied to the strengthening of concrete structures, the concrete substrate,

the reinforcing material, the adhesive and the FRP-to-concrete interface are affected by the freeze-thaw cycling.

Till now, a number of experimental studies have been focused on this field. Considerable degradations on

interfacial behavior of FRP-to-concrete joints in FT environments have been observed. To quantify the interfacial

degradation, a bond-slip damage model of FRP-to-concrete joint subjected to freeze-thaw cycles was established

in this work. A finite element (FE) model was further established for the analysis of FRP strengthened RC beams

subjected to FT cycles (Fig. 1). To consider the interfacial degradation, the proposed bond-slip damage model was

implemented in the FE models visa cohesive elements. Based on the numerical calculations, it can be found that

the interfacial degradation decreases the ductility of the strengthened beams significantly (Fig. 2). Moreover, the

influence of interfacial bond degradation on the performance of FRP strengthened RC beams is not as much as

that of the FRP-to-concrete joints (Fig. 3).

Fig. 1 FE model of FRP strengthened RC beams

0 2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

70

80

Load

(kN

)

Mid-span deflection (mm)

Reference

100 cycles

200 cycles

300 cycles

0 100 200 3000.5

0.6

0.7

0.8

0.9

1.0

No

rmal

ized

FR

P d

ebo

nd

ing

str

ain

FE cycles

FE_beam-FT

FE_beam-FT+0.35Pu

Lap joint-FT

Lap joint-FT+0.35Pu

Fig. 2 Load-deflection curves Fig. 3 Comparison of FRP debonding strain



254


INFLUENCE OF BOND DETERIORATION ON THE FLEXURAL RESPONSE OF

FRP STRENGTHENED RC BEAMS

Rebecca Gravina1, Hasret Aydin1, Philip Visintin2 1 RMIT University, School of Engineering, Melbourne Australia, 2The University of Adelaide, Adelaide Australia

KEYWORDS

Strengthening and repair, Modelling, Durability, long-term performance, Bond and interfacial stresses, Reinforced

concrete.

ABSTRACT

Bonding fibre-reinforced polymer (FRP) composites to tensile faces of deficient concrete structures as a means of

increase loading capacities and prolonging service life is now common practice. Although FRP application for

flexural strengthening is widespread, there is uncertainty surrounding the long-term durability of these

strengthening systems. Unlike conventional reinforced concrete flexural members, which are designed to fail in a

ductile manner, that is steel yielding followed by concrete crushing, FRP-strengthened member are susceptible to

brittle debonding failures. The focus of this study is on intermediate-crack (IC) debonding which is typically

isolated by means of shear bond tests. In this paper, a previously developed partial-interaction moment-rotation

approach for IC debonding is applied to sets of experimental data in published literature to extract bond

characteristics from the FRP-to-concrete interface. The bond characteristics are extracted from deteriorated

members to assess the changes at the bond level and are compared with predictions from existing bond-slip models

for deteriorated joints. Using the approach, it is found that the environmental loading of FRP-strengthened flexural

members generally reduces both the maximum bond stress the slip necessary to initiate IC debonding, thereby

compromising the ductility and strength of the member



255


TIME-DEPENDENT RELIABILITY ANALYSIS OF FRP STRENGTHENED

REINFORCED CONCRETE BEAMS CONSIDERING MATERIAL DETERIORATION

AND STOCHASTIC LOADING

Xiaoxu Huang1, Yingwu Zhou1 1School of Civil Engineering, Shenzhen University, Shenzhen, China, Email: [email protected]

KEYWORDS

Time-dependent reliability; Fiber reinforced polymer ; deterioration; stochastic loading

ABSTRACT

In reality, as time goes on, degradation in components (e.g. material properties) and stochastic operating conditions

(loading, environment conditions, etc.) may cause components or structures to deliver inconsistent performance

and sometimes even to fail prematurely. Thus, structural reliability is in essence a time-dependent property that

cannot be well represented within the framework of time-independent reliability. FRP (fiber reinforced polymer)

composites are widely used for the renewal of existing concrete structures. In this paper, a theoretical study of the

time-dependent reliability analysis of FRP reinforced concrete (RC) beams subjected to material deterioration and

stochastic loading is performed. The rules of material deterioration (i.e., steel and concrete), are represented by

deterministic functions. The loading is represented by a Gaussian stochastic process. A surrogate model based

method is adopted, in which the instantaneous limit state function is approximated by an active learning surrogate

model. Compared with other time-dependent reliability methods, the surrogate model based method is more

efficient and accurate.



256


USE OF CFRP AS AN IMPRESSED CURRENT ANODE FOR THE CATHODIC

PROTECTION OF STEEL REINFORCED REBAR

X. Hallopeau 1, C. Tourneur 1, V. Buchin-Roulié 1 and J. Mercier 1 1 Freyssinet International & Cie, Rueil-Malmaison, France, Email: [email protected]

KEYWORDS:

corrosion, anode, carbon fiber, cathodic protection

ABSTRACT

This presentation reports the development of a new impressed current anode for the cathodic protection of steel

reinforced rebar in concrete.

The application of a DC current on a carbon fiber reinforced polymer, used both as a structural reinforcement and

as an anode surface, allows to polarize the steel in concrete.

It is then possible to combine the strengthening function with the development of a multifunctional composite

allowing protecting of steel rebar from corrosion and also allowing the monitoring of repairing function versus

time. Indeed, the cathodic protection is an electrochemical technique that minimizes the corrosion of steel in

contact with an ionically conductive medium. In this technique, the steel/electrolyte interface is electrically

polarized using external impressed current. For optimum protection, the polarization should be carried out

uniformly throughout the interface. Otherwise, the steel continues to corrode. The key to success in the

development of this surface anode-reinforcement is the possibility of obtaining uniform distribution of current.



257


EXPERIMENTAL AND NUMERICAL INVESTIGATION ON TORSIONAL

STRENGTHENING OF BOX RC STRUCTURES USING NSM FRP

Chandan C Gowda1, Joaquim A O Barros 2 & Maurizio Guadagnini3 1&2 University of Minho, ISISE, Department of Civil Engineering, Guimarães, Portugal

([email protected]); 3 The University of Sheffield, Department of Civil & Structural Engineering, Sheffield,

United Kingdom;

KEYWORDS :

Strengthening and repair; Experimental study ; Durability, long-term performance; Choose an element ...

Near surface mounted, box structures

ABSTRACT:

The near surface mounted (NSM) technique is a strengthening method that provides additional reinforcement by

means of strips or bars embedded into grooves made in the concrete cover of reinforced concrete (RC) elements.

The effectiveness of using NSM fibre reinforced polymer (FRP) bars or strips to enhance the shear and flexural

capacity of RC elements has been demonstrated over the past decade. However, the idea of using NSM FRP

reinforcement to address issues related to deficient torsional performance is yet to be explored. Torsional

strengthening of RC elements (e.g. bridge girders, transfer beams) may be necessary due to degradation of

materials, changes in the design codes, deficiencies in the initial design, changes in building usage etc. This paper

investigates the torsional strengthening of thin walled tubular RC beams using NSM CFRP laminates.

The experimental program involved testing of six box sectioned RC beams, including two reference beams (with

and without shear reinforcement) and four beams strengthened with different arrangements of NSM CFRP

reinforcement, providing varying longitudinal and transverse reinforcement ratios. All the strengthening proposals

resulted in significant increase in torsional moment capacity, ductility, stiffness in the elasto-plastic range and

were very efficient in arresting crack propagation, proving the effectiveness of NSM strengthening technique for

torsional strengthening. The proposed experimental program is described in detail and the main results are

presented and discussed.



258


MODELLING OF CFRP LAMINATES APPLIED ACCORDING TO THE ETS/NSM

TECHNIQUE

Carlos Nonato da Silva1, Jacopo Ciambella1, Joaquim Barros2, Inês Costa3 1 University of Rome “La Sapienza”, DIPARTIMENTO DI INGEGNERIA STRUTTURALE E GEOTECNICA, Rome Italy; 2 University of Minho, Escola de Engenharia, Guimarães Portugal;

3 civitest, Vila Nova de Famalicão, Portugal. (Carlos Nonato da Silva: [email protected])

KEYWORDS :

CFRP; Hybrid Strengthening; Direct Pull-out; Bond behaviour; Analytical model

ABSTRACT:

An effective method to increase the load-carrying capacity of existing reinforced concrete elements consists in the

addition of tension reinforcement in surface grooves cut along the cover on the tension side (for flexural

strengthening) or in the web (for shear strengthening) of these elements. A hybrid strengthening technique that

combines the advantages of Near Surface Mounted (NSM) technique and Embedded Through Section (ETS)

technique was recently explored for the simultaneous flexural/shear strengthening and flexural/punching

strengthening of RC beams and slabs, respectively by using an innovative CFRP laminate with rectangular shape

in the NSM part and circular shape in the ETS, and encouraging results were obtained. The inclined L-shape

laminate aims at increasing the shear/punching resistance of RC beams/slabs, whereas the central part of the

laminate provides flexural reinforcement to the RC elements. To evaluate the maximum tensile force, loaded-end

slip, free-end slip and strain values, direct pull-out tests were performed. The combination of three embedment

length values (LETS) (60, 120 and 180 mm) together with three inclination angles 15º, 30º and 45º as can be seen

in Figure 1.

In the paper, an analytical bond stress-slip relationship was determined for the innovative CFRP laminate. With

this purpose, a numerical method was developed, which uses the results obtained in the preliminary experimental

program. This method solves the differential equations that govern the slip evolution of the NSM/ETS CFRP

laminate technique, and takes into account the distribution of the slip and the bond stress along the bond length.

In the model was considered the variation of the tensile strain in the transition zone depth, due to the moment

generated by the geometric curvature, and the embedded length as beam on elastic foundation. Using a numerical

tool, the parameters that define the local bond stress-slip relationship and the friction between the materials are

obtained. After demonstrating the good predictive performance of the proposed model, the main conclusions and

the future work are presented.

Figure 1: Difference between the configurations analysed

http://www.disg.uniroma1.it/

http://www.disg.uniroma1.it/



259


EFFECT OF STEEL REINFORCEMENT IN FLEXURAL STRENGTHENING OF RC

SLABS USING PRESTRESSED NSM CFRP LAMINATES

Mohammadreza Mostakhdemin Hosseini1, Salvador Dias2, Joaquim Barros2 1 Department of Civil Engineering, Mahdishahr Branch, Islamic Azad University, Mahdishahr, Iran;

2 ISISE, Department of Civil Engineering, University of Minho, Guimarães, Portugal

([email protected])

KEYWORDS:

New composite materials, systems and strengthening techniques; Experimental study ; Prestressing with FRP

composites; RC slabs

ABSTRACT:

The influence of the percentage of the longitudinal tensile reinforcement on the effectiveness of the NSM (near

surface mounted) technique with prestressed CFRP (carbon fiber reinforced polymer) laminates for the flexural

strengthening of RC (reinforced concrete) slabs was assessed experimentally. Four RC slabs were tested, a

reference slab (without CFRP), and three slabs flexurally strengthened using NSM CFRP laminates with different

prestress levels, which was considered a percentage of their ultimate tensile strength namely: 0%, 20% and 40%.

The tested slabs had a percentage of longitudinal tensile steel bars of about 0.62% (ρsl =0.62%), while the CFRP

strengthening percentage was approximately 0.085%. The results obtained indicated that prestressing CFRP

laminates with the NSM technique is a suitable strategy to increase the flexural capacity of RC slabs, not only in

ultimate but also in serviceability limit states. By applying NSM CFRP laminates prestressed at 20%, the service

and maximum loads increased by 42% and 59%, respectively, compared to the reference slab. The values of service

and maximum loads increased by 79% and 64%, respectively when applying laminates prestressed at 40%.

Considering available experimental results obtained with the same test setup, but using RC slabs with lower

percentage of the longitudinal tensile reinforcement (ρsl =0.35%), it can be concluded that the increase of the

percentage of the longitudinal tensile reinforcement has a detrimental effect on the effectiveness of NSM technique

with prestressed CFRP laminates in terms of the increase of service and ultimate loads.



260


FLEXURAL CAPACITY OF FRP RC BEAMS STRENGTHENED WITH NSM

TECHNIQUE

C. Barris1, P. Sala2, J. Gómez2, Lluís Torres2 1 AMADE, University of Girona, Spain, e-mail : [email protected]

2 AMADE, University of Girona, Spain

KEYWORDS

Fields applications and case studies; Experimental study ; FRP internal reinforcement; Codes, standards and

design guidelines

ABSTRACT:

The use of near-surface mounted (NSM) technique for strengthening existing steel RC structures with Fibre

Reinforced Polymer (FRP) is generally accepted by engineers and designers of reinforced concrete (RC) structures;

its use can be either for repairing damaged elements or for improving load capacity for new requirements not

initially foreseen. Another well-accepted application of FRP reinforcement is its use as internal reinforcement,

especially in those cases where the structure is subjected to aggressive environments that might corrode steel

reinforcement. In that case, large deformations are expected to take place due to the low modulus of elasticity of

the FRP reinforcement. As a consequence, applying the NSM technique with CFRP bars or strips may provide a

unique opportunity to enhance not only the stiffness of the member but also the load capacity of the element

without providing metallic reinforcement, as long as compatibility of deformations is possible within each section

of the member.

This paper presents the preliminary results on an experimental program studying the flexural behaviour of five

internally reinforced Glass-FRP RC beams and one steel RC beam that had been previously tested under their

service load and later strengthened with Carbon-FRP strips using the NSM technique. The specimens were tested

under a six-point loading configuration until rupture. For comparison purposes, one GFRP RC beam was left

unstrengthened. The theoretical load-carrying capacity is assessed by a cracked sectional analysis (CSA) and it is

compared to the experimental results. Additionally, the concrete strain at the midspan section is experimentally

registered and compared to CSA predictions. It is observed that NSM results in an effective technique to enhance

the flexural capacity of RC beams internally reinforced with GFRP bars.

Figure 1: Concrete cover separation failure.




261


INFLUENCE OF ADHESIVE TYPE ON THE FLEXURAL BEHAVIOUR OF RC

SLABS STRENGTHEND WITH NSM-CFRP SYSTEMS

José Ricardo Cruz 1, José Sena-Cruz 1, Pedro Fernandes 1, Anja Borojevic 1, Arkadiusz Kwiecień 2, Bogusław

Zając 2 1 ISISE, Dep. of Civil Engineering, University of Minho, Portugal; 2 Department of Civil Engineering, The

Cracow University of Technology, Poland (corresponding author: [email protected])

KEYWORDS :

NSM; CFRP; Slabs; Flexural test; Adhesive.

ABSTRACT:

In the context of the strengthening of reinforced concrete (RC) structures, near surface mounted (NSM) technique

can be used by applying carbon fibre reinforced polymer (CFRP) laminates on the concrete cover of the structural

elements to be strengthened. An adhesive is used to fix the CFRP to concrete, which is responsible by the stress

transfer between the concrete and the CFRP, assuming a key role for the successful of the strengthening system.

Consequently, this composite action is responsible for the load carrying capacity and for the service behaviour of

the strengthened RC structures. The influence of the adhesive type on the overall performance of these

strengthened structures presents some research gaps in knowledge, as can be seen by the reduced number of studies

found in the literature about this topic. About externally bounded reinforcement (EBR) technique some

investigations on this theme can be found, however, about NSM technique, this type of studies is almost non-

existent. The studies already existing have shown that the use of flexible adhesives instead of stiff adhesives,

allows higher structural performance, including higher ductility.

This paper presents the results of an investigation on the flexural behaviour of RC slabs strengthened with NSM

CFRP systems using stiff (Adhesives 1 and 2) and flexible (Adhesive 3) adhesives. For this purpose, an

experimental program (see Table 1) was carried out, being considered two study variables: (i) the adhesive type

and (ii) the existence or not of pre-cracking on the structural response. Flexural slab tests (see Figure 1) were used

to characterize the differences on the slab’s structural behaviour depending on the parameters tested. Proper

instrumentation was used to assess (i) the applied force, (ii) the vertical displacements along the longitudinal axis,

(iii) the strains on steel bottom reinforcement, (iv) the strains on concrete at the top fibre, and, (v) the strains along

the CFRP laminate.

Regarding to the results obtained (see Table 1 and Figure 2), it is clear the dependence the response force versus

mid-span vertical displacement and mid-span CFRP strains on the adhesive type as well as of the presence or

absence of pre-cracking. However, it was verified that the maximum load attained is less dependent on the adhesive

mechanical properties, as well as on the presence or absence of pre-cracking. Thus, with the flexible adhesive, the

maximum load attained is about 80% of the maximum load achieved in the slabs where stiff adhesives were used.

The maximum load achieved is similar with presence or absence of pre-cracking. The failure of the CFRP laminate

was observed with stiff adhesives while with the flexible one, CFRP debonding was observed (see Figure 3). Thus,

a higher ductility was observed by using flexible adhesive.

Figure 1: Flexural slab test.

F/2 F/2

SG5

2600

300300450450100 100450 450

LVDT1 LVDT2 LVDT3 LVDT4 LVDT5



262


Table 1: Experimental program/ results.

Experimental program Results

Type of

adhesive

Pre-

cracking(1)

CFRP

cross-

section,

wf × tf

[mm2]

Slab’s

denomination

Flexural stiffness Crack

initiation Yielding Maximum

Ductility

parameter FM

𝐾I 𝐾II 𝐾III 𝛿cr 𝐹cr 𝛿y 𝐹y 𝛿max 𝐹max 휀𝑓max 𝛿max/𝛿y --

[kN/mm] [mm] [kN] [mm] [kN] [mm] [kN] [10−3] [-] --

- - - SL_REF 7.75 0.78 0.01 0.71 7.57 20.17 21.47 158.43a 23.56a - - -

ADH1 Yes

20×1.4

SL_ADH1_U 9.57 1.10 0.40 1.25 10.86

(43%) 21.85

31.93

(49%) 74.04

52.87

(124%) 12.06 3.39 F

ADH2 Yes SL_ADH2_U 8.95 1.07 0.41 1.35 10.52

(39%) 22.47

31.11

(45%) 74.95

52.08

(121%) 12.49 3.34 F

ADH3 Yes SL_ADH3_U 7.94 1.28 0.34 1.58 10.86

(43%) 20.79

27.35

(27%) 72.24

42.71

(81%) 8.46 3.47 D

ADH1 No SL_ADH1_C 6.30b 1.92 0.41 1.32b 7.16b 18.95 31.58

(47%) 68.87

51.53

(119%) 12.46 3.63 F

ADH2 No SL_ADH2_C 6.03b 1.91 0.40 0.99b 7.78b 17.36 30.47

(42%) 69.33

51.06

(117%) 12.02 3.99 F

ADH3 No SL_ADH3_C 5.38b 1.81 0.34 1.06b 6.18b 13.97 24.61

(15%) 69.54

41.82

(78%) 8.33 4.98 D

Notes: ADH1 – Adhesive 1; ADH2 – Adhesive 2; ADH3 – Adhesive 3; No – absence of pre-cracking (Uncracked); Yes – presence of

pre-cracking (Cracked); FM = Failure modes; F = CFRP failure; D = Debonding failure of the CFRP laminate accompanied by cohesive failure

of the adhesive; the values between parentheses represent the increase in load capacity for each phase compared to SL_REF. a Maximum values reached during the test without failure of the slab (by concrete crushing or failure of the longitudinal tensile steel bars). b Values obtained from

the pre-cracking phase.

(a) (b)

Figure 2: Force vs. mid-span displacement: (a) uncracked and (b) cracked series.

(a) (b)

Figure 3: Failure modes: (a) CFRP failure (stiff adhesives) and (b) CFRP debonding (flexible adhesive).

0 30 60 90 1200

15

30

45

60

Fo

rce

, F

[k

N]

Mid-span displacement, [mm]

SL_REF

SL_ADH1_U

SL_ADH2_U

SL_ADH3_U

0 30 60 90 1200

15

30

45

60

Fo

rce

, F

[k

N]

Mid-span displacement, [mm]

SL_REF

SL_ADH1_C

SL_ADH2_C

SL_ADH3_C



263


NSMR STRENGTHENING OF SHORT RC BEAMS USING ACTIVATED

ANCHORAGE

J.W. Schmidt 1, K. D. Hertz 1 and P. Goltermann 1 1 Danish Technical University, DTU, Department of civil engineering, Denmark, Email: [email protected].

ABSTRACT

NSMR (Near surface mounted reinforcement) systems often provides brittle failure mechanisms as well as little

ductility compared to conventional steel reinforced concrete beams. Additionally the most common failure modes

occur in the concrete adherent, which means that the high capacity of the CFRP material often is left un-utilized

at failure. One of the aims in the ongoing research at DTU Civil Engineering concerns anchoring of NSM CFRP

reinforcement in a way that provides utilization, ductility, and controlled failure mechanisms. The work presented

in this paper concerns the effect of NSMR system activation by the use of specially developed anchor blocks. The

anchored NSMR rods are activated to a little tension magnitude, before curing of the adhesive. An anchored

strengthening effect of approximately 45% of the reference beam was reached when using the 6mm circular rods

(ANSMR-6) whereas this effect increased to 60% when using the 8mm CFRP rod (ANSMR-8) configurations. In

addition, a strengthening effect of 34% was obtained, in the un-anchored NSMR configurations. The anchored

configurations furthermore provided significantly increased ductility compared to the un-anchored systems, where

some of the strengthened beam reached deformations identical to the reference beams.



264


COMPARISON BETWEEN DIFFERENT STRENGTHENING SCHEMES FOR

PUNCHING SHEAR OF FLAT PLATE SLABS

S. Elkholy 1,2, A. Godat 2, M. Elassaly 1 and E. Rabee 1 1 Fayoum University, Department of Civil Engineering, Egypt

2 United Arab Emirates University, Department of Civil and Environmental Engineering, UAE, Email:

[email protected].

KEYWORDS

Fibre-reinforced polymers, finite element analysis, flat plate slab, strengthening, parametric study, punching shear

capacity.

ABSTRACT

This study presents a finite element model that is developed to examine various FRP strengthening schemes to

mitigate the punching shear failure of flat plate slabs. In this study, nonlinear material behaviour of the plain

concrete, steel reinforcing bars and FRP composites are simulated with appropriate constitutive models and

structural elements. The accuracy of the model is established through comparing the finite element predictions

with existing experimental results. Once the accuracy of the model is accepted, it is employed to investigate various

FRP parameters that may influence the punching shear failure of flat plate slabs. Thirty six models are carried out

to investigate the following parameters: (a) width of FRP strips; (b) thickness of FRP strips, and (c) length of FRP

strips. The schemes considered include various numbers of strips around the column, and FRP strips with low,

medium and high strengths. Numerical results are presented in terms of ultimate punching shear capacity and load-

deflection relations. In light of results obtained, the scheme and mechanical properties of FRP strips around the

columns reduces the length of the strip required to achieve the ultimate punching capacity.




265


INFLUENCE OF THE AREA OF CFRP LAMINATES ON IMPROVING THE

PUNCHING SHEAR CAPACITY OF SLAB-COLUMN CONNECTION

*H. Akhundzada 1, *T. Donchev 1 D. Petkova 1 and N. Kolikar 1 1 Kingston University, Department of Civil Engineering, London, United Kingdom

Email: [email protected], [email protected]

* Corresponding Authors

ABSTRACT

Punching shear failure is very common failure type with flat slabs which could lead to progressive collapse of the

structure. The strength of the existing flat slabs could be reduced over a number of different reasons mainly due

to corrosion of reinforcement, creating openings for services, poor quality control during the construction and

other factors. The strengthening of flat slabs is required to prevent punching shear failure. This research presents

the experimental findings of the use of CFRP laminates as externally bonded reinforcement to improve the

punching shear capacity of flat slabs. In this experimental program one control and three samples strengthened

with CFRP laminates were casted and tested against punching shear failure. The slab-column connection had

dimensions of 1500x1500x120mm slab and 150x150x150mm column head. The samples had tensile reinforcement

of 15H8 in both directions and 8H6 compressive reinforcement. The samples were strengthened with CFRP

laminates and the area of the laminates was varied. The aim of the research is to investigate the role of width of

the laminates and the effect of additional anchorage for strengthening purposes. The strengthened samples showed

significant improvement in terms of peak load, recording an increase of up to 30% relative to control sample. The

strengthened samples had relatively higher stiffness which shows an increase of up to 64%. The highest ultimate

load was recorded for sample strengthened with 50mm laminates. Additional increase in the width of the laminates

resulted in decreasing the effectiveness of the additional anchorage. This effect is due to reduced distance between

the column and corresponding overlapping anchorage area with cracked zone. Further analysis and suggestions

for the future developments in this area are offered.




266


DEVELOPMENT OF THE NEW CFRP STRIP PRESTRESSING SYSTEM FOR

STRUCTURAL STRENGTHENING

Piątek Bartosz1, Siwowski Tomasz1 1 Rzeszow University of Technology, Department of Roads & Bridges, Rzeszow, Poland (corresponding author:

[email protected])

KEYWORDS:

New composite strengthening techniques; Experimental study; Prestressing with FRP composites.

ABSTRACT:

Tensioning of the CFRP strips allows to increase load bearing capacity and stiffness of strengthened structural

elements and enhances composite material utilisation in comparison with passive external bonding technique.

Since 1998, we have been observing a dynamic development of CFRP prestressing systems worldwide. There is

a lot of systems available on the market and more solutions have been currently tested and developed in

laboratories all over the world.

The paper presents a research on the new Polish system called Neoxe Prestressing System II. The research included

development of two main system components: special steel anchorages mounted on both ends of a single CFRP

strip and a tensioning device (Figure 1). The anchorages are made of two steel plates. The CFRP strip end is placed

between steel plates and bonded by epoxy resin and gripped by screws. Anchorage has two functional areas:

external and internal. The strip is clamped within the internal area. The external area includes holes for anchoring

the plate to the concrete surface and threaded holes for mounting the tensioning device. The tensioning device

comprises three separately installed elements: guide rails, carriage (bolted to the active anchorage) and hydraulic

jack.

The research comprised series of static and fatigue tests on anchorages, on strengthened beams as well as on-site.

The static tests revealed the excellent anchorage capacity and also sufficient fatigue strength. The efficiency of the

system was examined in tests on RC beams. For this purpose six full-scale RC beams were tested in four point

bending scheme. Beams strengthened by prestressed strips exhibited over 50% higher carrying capacity than the

unstrengthened ones. They also showed a lower deflections and higher crack resistance. The last step of developing

the system was an in-field application on existing RC bridge and testing it before and after strengthening. The

system was examined, its efficiency was confirmed in laboratory as well as in-field tests and now it is ready to be

used in construction.

Figure 1: Scheme of active anchorage (on left) and tensioning device (on right)



267


EFFECTIVENESS OF FABRIC REINFORCED CEMENTITIOUS MORTAR (FRCM)

IN STRENGTHENING BEAMS WITH HIGH REINFORCEMENT RATIOS

T. N. S. Billows1 and A. Rteil2 1 The University of British Columbia, School of Engineering, Canada Email: [email protected]

2 The University of British Columbia, School of Engineering, Canada, Email: [email protected]

KEYWORDS

Flexure strengthening, Fibre reinforced cementitious material (FRCM), Textile reinforced mortar (TRM), Flexure

capacity, Ductility, Stiffness, Design Guidelines.

ABSTRACT

Fabric reinforced cementitious mortar (FRCM), sometimes called textile reinforced mortar (TRM), has emerged

as an alternative strengthening and repair method to current practices such as fibre reinforced polymer (FRP). The

research adopted in this paper set out to determine the flexural strength improvement of RC beams with a high

reinforcement ratio. Three variables were studied namely, different textile ratios, different fabric materials and

different anchorage methods. Five full-scale (200 x 300 x 4000 mm) RC beams (1 control, 4 strengthened) were

cast and tested under monotonic four-point bending conditions. Ultimate flexural capacity, ductility, stiffness, and

failure mode were taken as performance indicators. Load carrying capacity results were compared to design

guidelines set out by ACI Committee 549. Flexural strength improvements were slight with a maximum value of

16.3%, failure mode remained consistent, pre-yielding stiffness did not change and energy absorption increased

with the addition of fabric. Results also indicated that while ACI 549 underestimated the load carrying capacity of

most strengthened specimens, it overestimated the strength in some of them.



268


DESIGN OF REINFORCED CONCRETE T-BEAMS STRENGTHENED IN SHEAR

WITH EXTERNALLY BONDED FRP COMPOSITES

Samir Dirar 1,2, Michael Qapo 3, Marios Theofanous 1 1 Department of Civil Engineering, University of Birmingham, Birmingham, B15 2TT, United Kingdom

2 Email: [email protected] 3 AECOM Ltd, Birmingham, B4 6AT, United Kingdom

KEYWORDS :

Strengthening and repair; Standard ; Codes, standards and design guidelines; Bond and interfacial stresses;

Concrete; Beams

ABSTRACT:

Current design guidelines for concrete structures strengthened with externally bonded (EB) fibre-reinforced

polymer (FRP) reinforcement do not differentiate between the shear design of rectangular and T-beams.

Nonetheless, EB FRP shear-strengthened rectangular and T-beams can have significantly different behaviour. In

rectangular beams, EB FRP reinforcement may be bonded to the full depth of the beam web and therefore can

effectively join the tension and compression chords. On the other hand, the presence of the slab in T-beams limits

the effective depth of the EB FRP reinforcement. This can result in current design guidelines overestimating the

shear strength enhancement offered by the FRP reinforcement in the case of T-beams.

This paper presents a design model for reinforced concrete (RC) T-beams strengthened in shear with EB FRP

composites. In the proposed design model, the FRP contribution to shear resistance is based on the 45° truss

analogy and the FRP strain at failure is derived from direct-pull test results from the published literature. The

predictions of the proposed model, together with those of Concrete Society TR55 and ACI 440.2R-17, were

evaluated using an experimental database comprising 48 RC T-beams. The proposed model had an average

predicted-to-experimental shear strength enhancement ratio of 1.062 and a standard deviation of 0.470. The

average predicted-to-experimental ratios of TR55 and ACI 440.2R-17 models were 1.139 and 1.277, respectively,

with standard deviations of 0.498 and 0.642, respectively. Not only does the proposed model generate more

consistent predictions, but it also has a greater conservative nature, providing fewer overestimated predictions

compared to current international design guidance (see Figure 1).

(a) (b) (c)

Figure 1: Predicted versus experimental FRP shear contribution: (a) Proposed model, (b) TR55 and (c) ACI

440.2R-17



269


FRP SHEAR STRENGTHENED RC BEAMS: AN ANALYTICAL MODEL

Cheng Chen1, Lijuan Cheng 2 1 Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University,

Shenzhen, 518060, China; 2 Department of Civil and Environmental Engineering, University of California -

Davis, One Shields Ave., Davis, CA, 95616, USA, [email protected]

KEYWORDS :

All FRP and smart FRP structures; Modeling; Characterization of FRP and FRC materials/systems; Bond and

interfacial stresses

ABSTRACT:

In this study, a single crack-based model is proposed to predict the contribution of fiber reinforced polymer (FRP)

reinforcement to the shear resistance of strengthened reinforced concrete (RC) beams. The shear crack of FRP

strengthened RC beams is assumed to occur along the principal stress trajectory (PST) where concrete is subject

to principal tensile stresses. A bilinear bond-slip model is adopted for the cohesive stresses due to FRP

reinforcement and steel stirrups, and the exponential model is chosen for the cohesive stress due to aggregates.

The crack width at the intersections of the shear crack and the FRP reinforcement is assumed to be the slip of the

FRP reinforcement to obtain a stage-wise solution to the distributed strain of FRP reinforcement and its

corresponding contribution to the shear resistance. To verify the precision of the model, two experimental studies

are selected, where the proposed model predicts well on shear crack trajectory, FRP strain distribution, stirrup

strain distribution, and FRP contribution to the overall shear resistance.

1. OBJECTIVES

Most existing analytical models to predict the shear contribution of the FRP reinforcement are essentially

based on the calibration of the effective bond length and the effective strain of FRP reinforcement, which shows

great scattering and inconsistency among different experimental researches. To address this drawback, this paper

develops an innovative model for prediction the shear resistance contribution of the EB and the NSM FRP

reinforcement.

2. RELEVANT RESULTS

2.1 Principal stress trajectory (PST)

The shear crack of the shear-strengthened RC beam in Fig. 1(a) is assumed to appear along the principal stress

trajectory (PST), which is subjected to the principal stress using the Mohr’s Circle:

𝜎1 =𝜎

2+ √

𝜎2

4+ 𝜏2 (1a)

tan (2𝜃𝑐) =2𝜏

𝜎 (1b)

where σ = normal stress; σ1 = principal stress; θf = orientation of principal stress; and τ = shear stress. The

construction of PST starts from the bearing point of the concentrated load P, and extends towards the free end with

the direction of principal stress defined in Eq. (1b) [Fig. 1(b)].

(a)

(b)



270


Figure 1 Principal stress trajectory (PST): (a) configuration; and (b) construction of PST

2.2 Crack profile

The shear crack is subject to the principal stress and multiple cohesive stresses from aggregates, stirrup and

FRP reinforcement, as illustrated in Fig. 2(a). The width of shear crack can be obtained by:

𝛿(𝑥)

2=

4

𝐸1∫ 𝐺(𝑠′, 𝑎, ℎ)𝑑𝑎′ ∫ 𝐺(𝑠′, 𝑎′, ℎ)[𝜎1(𝛿) − 𝜏𝑐(𝛿)]

𝑎′

0

𝑎

𝑠𝑑𝑠′ (2)

where E1 = concrete elastic modulus; τc = total cohesive stress due to aggregates, steel stirrups and FRP

reinforcements; a = total crack length, which is to be determined later; s = coordinate along PST; s’ and x’ =

integration variables; and G = Green’s function.

Figure 2 Illustration of: (a) stresses on shear crack; and (b) local slip of EB FRP

2.3 Shear contribution of FRP and steel stirrups

Once the crack width is known, the local slip of FRP reinforcement (δ0) can be calculated using the orientation

between the shear crack and the FRP reinforcement [Fig. 2(b)]:

𝛿0 = −𝛿

cos (𝜃𝑓+𝜃𝑐) (3)

where δ0 =length of the FRP between crack surfaces; and θf = orientation of the FRP reinforcement. For any given

FRP reinforcement intersected by the shear crack [Fig. 3(a)], it can be treated as two segments (Lf1 and Lf2)

subjected to loaded end slip (δ01 and δ02), as displayed in Fig. 3(b).

Figure 3 Partitioned EB FRP reinforcement: (a) side view; and (b) section A-A

Through iterations of the loaded end slip, δ01 and δ02, and imposing the force equilibrium at the shear crack

intersection, the bond stress (τ2) and tensile strain (ε2) of the FRP reinforcement can be solved. Then, the

contribution of the FRP reinforcement to shear capacity can be attained as follows:

𝑉𝑓 =𝐸2𝐴2(cot θ𝑓+cotθ𝑐)sinθ𝑓 cos θ𝑓

𝑛𝑓𝑠2∑ [∫ 휀21(𝑙)

𝐿𝑓1

0𝑑𝑙 + ∫ 휀22(𝑙)

𝐿𝑓2

0𝑑𝑙]

𝑛𝑓

1 (4)

where dfv = the effective shear depth of the cross-section; E2 = elastic modulus of the FRP reinforcement; Lsh =

spacing of the FRP reinforcement; and A2 = area of the FRP reinforcement.

2.4 Verification

A comprehensive verification is conducted here to compare the predicted flexural behavior to the experimental

results from four experimental studies.

(a) (b)

(a) (b)



271


Figure 4 Verification of the proposed model

3. CONCLUSIONS

The shear crack is subjected to the cohesive stresses from the aggregates, steel stirrups and FRP

reinforcements. The principal stress trajectory serves as good approximation to the experimental shear crack. The

proposed mode is capable of predicting flexural behavior in terms of the shear crack location, the FRP strain, and

the steel stirrups strain.



272


CRACK PROPAGATION OF RC BEAM STRENGTHENED IN SHEAR BY CFRP

GRID

Ngoc Linh Vu 1,2, Kimitaka Uji 1, Kentaro Ohno 1 1 Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Department of Civil and

Environmental Engineering, Tokyo, Japan 2 University of Transport and Communications, Department of Civil Engineering, Hanoi, Viet Nam

KEYWORDS :

All FRP and smart FRP structures; Experimental study ; Choose an element ...; Choose an element ... CFRP

grid, shear strengthened.

ABSTRACT:

This study researches on the cracking behavior of reinforced concrete (RC) beam strengthened in shear by Carbon

Fiber Reinforced Polymer (CFRP) grid and sprayed mortar. In the experimental program, two beams were

fabricated and tested under the four-point bending test; one is the control beam while the other was shear-

strengthened with CFRP grid. The two beams have been designed to the failure mode is diagonal failure. Acoustic

emission (AE) sensors were attached on the two beams to monitor the crack development from the starting point

till the ultimate state. The actual observed fact of the crack propagation is combined with AE technique result to

conclude the better understanding of the formation and propagation of diagonal cracks. As a result of the

experiments, micro-cracks in concrete beams occur and develop very early, even when the load is very low and in

the compressed area of the beam. In this research work, basing on the result from AE sensor and observation, the

comparison between the crack propagation of control beam and the shear strengthened beam is also presented.

Crack pattern of RC beam shear-strengthened with CFRP grid



273


INFLUENCE OF SIZE ON THE BEHAVIOR OF RC T-BEAMS STRENGTHENED IN

SHEAR WITH EXTERNALLY BONDED CFRP

Zine El Abidine Benzeguir1, Georges El-Saikaly2, Omar Chaallal3 1,2,3 Université du Québec, École de technologie supérieure (ÉTS), Department of Construction Engineering,

Montreal (Quebec), Canada (3corresponding author: [email protected])

KEYWORDS:

Strengthening; Experimental study; Size effect; Shear; Reinforced concrete beams; CFRP

ABSTRACT:

The size effect parameter is known to have a major impact on the shear strength of conventional reinforced

concrete (RC) beams. This has been demonstrated through well documented data from numerous research studies

since the 1960s. However, very few studies have been conducted to investigate the size effect of RC beams

strengthened in shear with externally bonded (EB) FRP composites. This is particularly relevant since the empirical

equations and analytical models proposed by the design guidelines for predicting the FRP contribution to shear

resistance of concrete structures were developed on the basis of experimental laboratory test data on relatively

small specimens, with no consideration of the beam size effect. Therefore, the applicability of such models to large

scale beams has not been thoroughly assessed and may well be questionable in view of some preliminary

investigations.

The objective of this investigation is to highlight the influence of size on the shear behavior of RC T-beams

strengthened in shear with EB CFRP sheets. The experimental program consisted of geometrically similar beam

specimens with three different effective depths, d, (small, medium and large), with and without internal transverse

steel reinforcement (Figure 1). The tests were conducted on control (unstrengthened) beams and on shear-

strengthened beams using CFRP sheets bonded continuously around the web in U-wrap configurations. The same

ratios of internal longitudinal steel, transverse steel, and EB CFRP were applied to the three different sizes of

beams. The results revealed the presence of a size effect amongst the test beams, where both the concrete and

CFRP contributions to shear strength were affected. This was particularly true for strengthened specimens without

internal transverse steel. The beams with a relatively high transverse steel ratio (spacing = d/2) showed a different

behavior, as affected by the contribution of the steel stirrups. As well, the shear crack control and the postponing

of premature debonding of the EB CFRP seem to mitigate the size effect.

Figure 1: Details of tested RC T-beams

508

102

d =

350

152

406

6-10M

4-25M

270

55

d =

175

95

220

7451

50

d =

525

275

605

6-30M + 2-25M

10M @ 265

6-10M

Ø4.76 @ 100

2-15M + 2-10M

4-Ø8

L = 3000 mmL = 4500 mm

L = 6400 mm

Ø8 @ 175



274


RELIABILITY OF DIC MEASUREMENTS FOR THE STRUCTURAL MONITORING

OF FRP RC ELEMENTS

Matteo Di Bendetti1, Javier Gómez2, Szymon Cholostiakow3, Hamed Fergani3, Cristina Barris2,

Maurizio Guadagnini3 1 The University of Sheffield, Multidisciplinary Engineering Education, Sheffield, U.K.

2 Polytechnic School of the University of Girona, Department of Mechanical and Construction Engineering,

Girona, Spain. 3 The University of Sheffield, Department of Civil and Structural Engineering, Sheffield, U.K.

KEYWORDS

Digital Image Correlation, experimental study, FRP reinforcement, reinforced concrete.

ABSTRACT

Digital image correlation (DIC) is a contactless measuring technique for full-field displacements and strains. With

regards to reinforced concrete members, the high density of measuring points offered by DIC could assist in

gaining invaluable insight into the complex interaction of different resisting mechanisms (e.g. bending, shear and

torsion) as well as into the onset and development of the resulting cracking behaviour. While DIC cannot still

compete in terms of measurement accuracy with state-of-the-art strain gauges, sufficiently reliable results can be

obtained by optimizing the set-up and some of the analysis parameters. This paper presents selected results of

different experimental programmes on concrete specimens reinforced with FRP bars, in order to study the

reliability, the advantages and the limitations of using DIC. In particular, two- and three-dimensional DIC

measurements are compared, with the latter having the advantage of not being affected by out of plane motions.

The examined DIC parameters include the angle between the optical axes of the two cameras as well as different

combinations of the subset, step and filter sizes. The effect of these variables on the reliability of DIC

displacements and strains is discussed and commented upon and the DIC results are validated against well-

established measuring techniques (Figure 10).

Figure 10: Vertical strains colourmap (left) and readings of the strain gauge on the external shear link (right)

for an FRP RC beam.

DIC @ 76 kN

Strain Gauge on

External Shear LinkSubset: 51 pixels

Step: 3 pixels

Filter: 5 subsets



275


REPAIR AND STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH

THE USE OF TEXTILE REINFORCED MORTARS (TRM’S)

Theofanis Krevaikas 1 Xi’an Jiaotong Liverpool University, Civil Engineering dept., Jiangsu Suzhou 215011,

(corresponding author: Theofanis.Krevaikas @xjtlu.edu.cn)

KEYWORDS:

Strengthening and repair; Experimental study ; FRC and cement composite materials; Codes, standards and

design guidelines

ABSTRACT:

In the aftermath of strong earthquakes beam elements suffer from severe damage which is mainly attributed

to low shear strength. Appropriate intervention schemes are sought to regain initial strength and stiffness. A

promising and innovative method is to externally apply textile reinforced mortars (TRMs) to increase both

the flexural and the shear strength. In this paper, the results of an ongoing experimental programme are

presented. A total of eight Reinforced Concrete (RC) beams with four different reinforcement ratios, were

subjected to four-point bending up to failure. Subsequently the RC beams were repaired with the use of patch

repair mortars and epoxy resins. In the next stage Basalt fibers in the form of textiles embedded in

cementitious mortars were externally applied to increase both the flexural and the shear strength of the beams.

One and two layers of TRMs were used. In the final stage, the beams were loaded up to failure using a four

point bending set-up. The experimental results showed that the beams regain their initial stiffness and most

of their original strength, proving that the use of TRMs is an effective alternative for strengthening statically

deficient RC elements.



276


ROBUST MODELING OF ANGLE-PLY LAMINATE RESPONSE FOR

STRENGTHENING APPLICATIONS

H. A. Rasheed 1 and H. Charkas 2 1 Department of Civil Engineering, Kansas State University, USA, Email: [email protected]

2 Electric Power Research Institute, Charlotte, NC, USA

KEYWORDS

Angle-ply laminates, FRP strengthening, nonlinear constitutive modeling

ABSTRACT

Stress-strain response of fiber-reinforced polymer composite laminates is typically based on 0o mechanical

parameters obtained from simple coupon testing. The nonlinear in-plane shear behavior, for angle-ply laminates,

is recognized long ago. Further research has shown that the multiaxial behavior affects the stress-strain relationship

in the transverse direction and its coupling with in-plane shear response. This paper utilizes data from uniaxial 0o

coupons, (θ1o)ns and (θ2

o)ns symmetric angle-ply laminates to determine a complete constitutive material model

for any other angle-ply layup (θ3o)ns. Damage-based classical lamination theory is used to assemble the ply

stiffness for global axial tensile response in terms of the secant transverse modulus E22s and the secant in-plane

shear modulus G12s values. The nonlinear transverse and in-plane shear stress-strain curves are extracted

analytically from the global experimental data obtained for two fiber orientations of symmetric angle-ply

specimens, using a dual alternating fast-converging procedure. In an example application, (45o)ns and (75o)ns are

tested experimentally. Then, they are used to recover the nonlinear local in-plane shear and transverse direction

behavior respectively. The resulting material models are used to predict the response of other angle-ply laminates

made from the same composite material. Furthermore, 45o laminates are examined to strengthen a reinforced

concrete T beam illustrating their potential benefits.

.




277


FLEXURAL BEHAVIOR OF PRE-CRACKED FRP BEAMS STRENGTHENED

WITH CARBON FIBER LAMINATES

Himanshu Chawla1 and Shamsher Bahadur Singh2

1&2 Birla Institute of Technology and Science, Pilani, Civil Engineering Department, Pilani and India


KEYWORDS

Carbon fiber laminates, Cracked beam, Experimental study, Strengthening and repair.

ABSTRACT This paper presents the experimental investigation on the cracked pultruded beams strengthened with carbon fiber

reinforced polymer (CFRP) laminates. Flexural responses were determined for CFRP strengthened beams having

length-to-depth (L/d) ratios 3 and 7. Beams had the crack length of 75 mm on the compression web-flange junction

at the mid-span of the beam. The length of carbon fiber layers were provided 175, 225 and 275 mm. Flexural

responses of beams was determined under three-point bending test. It is observed that the beam having L/d ratio 7

and carbon fiber layers of length 175 mm, failed by debonding of the carbon fiber layers, while other beams of

L/d ratio 7 and bonded lengths 225 and 275 mm failed by local failure of compression flange. Moreover, beam

having L/d ratio 3 and strengthened with carbon fiber layer throughout the length of beam has strength and stiffness

equivalent to the un-cracked beam.



278


Fire blast and impact loading



279


BLAST RESPONSE OF RC SLABS WITH EXTERNALLY BONDED

REINFORCEMENT

Azer Maazoun 1,2, Bachir Belkassem 2, Rodrigo Mourão 2, Stijn Matthys 3, D.Lecompte2 , John Vantomme 2 1 Ghent University, Magnel Laboratory for Concrete Research, Gent, Belgium, ([email protected])

2 Royal Military Academy, Civil and Materials Engineering Department, Brussels, Belgium 3 Ghent University, Magnel Laboratory for Concrete Research, Gent, Belgium

KEYWORDS :

Blast loading; Externally bonded reinforcement; Explosive Driven Shock Tube; Dynamic response; RC slab;

ABSTRACT:

The present paper proposes a detailed analysis of the efficiency of externally bonded reinforcement (EBR) on

reinforced concrete slabs (RC) under blast loads using explosive driven shock tube (EDST). This study focuses on

four tests which have been performed on RC slabs retrofitted with CFRP strips, simply supported, subjected to

explosions for a constant charge weight. Maximum deflection and strain distribution in the concrete and CFRP

strips are recorded using digital image correlation (DIC) measurement. Moreover, pressure transducers are fixed

at the end of the tube to measure the incident pressure of each experiment. Following the explosion, the RC slabs

are submitted to a dynamic vibration in both directions and during the first inbound displacement phase, the kinetic

energy of the retrofitted specimen is stored as elastic strain energy in CFRP strips. All this elastic strain energy

stored in FRP strips is violently released as kinetic during the rebound phase of the slab. The results indicate that

EBR increases significantly the flexural capacity and the stiffness of RC slabs under blast loads.

Figure 1 : Experimental setup for blast tests



280


EFFECT OF THE GEOMETRY AND IMPREGNATION OF THE TEXTILE

REINFORCEMENT ON THE MECHANICAL AND THERMOMECHANICAL

PROPERTIES OF A TEXTILE REINFORCED CONCRETE (TRC)

Tala Tlaiji1, Xuan Hong Vu1, Emmanuel Ferrier1, Amir Si Larbi2 1 Laboratoire des Matériaux Composites pour la Construction LMC2, University of Lyon 1, Villeurbanne,

France;

2 Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), University of Lyon, st-Etienne, France

([email protected])

KEYWORDS:

Textile geometry; Textile impregnation; Temperature; Characterization of TRC materials/systems

ABSTRACT:

The global behavior of a textile reinforced concrete (TRC) is influenced by the geometry and the impregnation of

the textile reinforcement. This study gives an overview of some material properties influencing the mechanical

performance of TRC composite. Focusing on the development of E-glass reinforced Inorganic Phosphate Cement

matrix composites for structural applications in civil engineering, a development of a specific experimental

procedure allows identifying the tensile properties (resistance, stiffness, deformation) until failure and the crack

width of TRC composite. In this study, the TRC composites tested are made with two different geometries of

textile, either the unidirectional E-glass or the hooked-shape E-glass, with and without the impregnation. Such

differences may affect the bonding properties between the textile reinforcement and the matrix as well as the

overall tensile performance. Moreover, an X-Ray tomography observation was carried out to characterize the

interface matrix/textile. Various effects of the geometry and impregnation of textile in the TRC were observed and

discussed. The best performance is observed for the TRC composite with unidirectional E-glass fiber. Its ultimate

strength is about 2 times greater than that of the TRC composite with hooked shape.

The use of oriented textiles in the main direction of stresses leads to an increase in the mechanical performance of

the TRC composite. Moreover, the interaction between the matrix and the textile reinforcement is improved for

the TRC composite with unidirectional fibers when the textile reinforcement is impregnated by a resin. The

resistances of these TRC composites have increased and their deformations have decreased, although their opening

of the cracks are much reduced. Whereas for the second geometry (hooked shape), the fiber’s impregnation has

no marked influence. Finally, the behavior of the best performing composite, which is formed with unidirectional

E-glass fibers, is then identified as a function of several temperature levels (25°C, 200°C, 400°C and 600°C). It

presents a severe drop between 25°C and 200°C which is explained by a thermomechanical analysis (TMA).

ACKNOWLEDGMENTS

This research was performed with the financial subvention of the European Regional Development Fund of the

European Union and of the Rhône-Alpes-Auvergne region, France for the lot 5 “Characterization of composite

materials” of the PRORETEX II research project. This project is the collaborative research project between four

industrial partners (SULITEC - project leader; FOTIA; ER2I; CIMEO) and two academic partners (UCBL/LMC2;

ENISE/LTDS). We also would like to thank the team of technicians (Mr. Emmanuel JANIN, Mr. Nobert

COTTET) from the Civil Engineering Department at IUT Lyon 1 and LMC2, University Lyon 1 for their technical

support.



281


EXPERIMENTAL STUDY OF THERMOMECHANICAL PERFORMANCE OF CFRP

REINFORCED CONCRETE STRUCTURE SUBJECTED TO ELEVATED

TEMPERATURE

Phi Long NGUYEN1,2, Xuan Hong VU1, Emmanuel FERRIER1 1 Université de Lyon, Université Lyon 1, Laboratory of Composite Materials for Construction (LMC2), 82 bd

Niels Bohr, F-69622 Villeurbanne, France. Mail: [email protected], xuan-hong.vu@univ-

lyon1.fr, [email protected] 2 Ho Chi Minh City University of Transport, Faculty of Construction Engineering, Campus 1: Number 2, D3

Street, Ward 25, Binh Thanh Disctrict, Ho Chi Minh City, Vietnam

KEYWORDS

CFRP; CFRP reinforced concrete ; external bonding reinforcement (EBR); near surface mounted (NSM); thermo-

mechanical condition; ,elevated temperature

ABSTRACT:

In recent decades, the use of carbon fibre reinforced polymer (CFRP) becomes popular in civil engineering to

reinforce the concrete structure such as columns, beams and slabs. It is because this material has good strength to

weight ratio as well as good resistance in corrosion and fatigue. In reinforcing concrete structures, CFRP is used

following two basic methods: externally bonding reinforcement (EBR) and near surface mounted (NSM). The

application method is selected depending on the type of the structure, the use of the reinforced structure and

workability condition. Recent researches indicated that the NSM seemed to be the better alternative EBR for

delaying the debonding failure and thus allowing CFRP to be exploited more efficiently. In civil engineering, when

a CFRP reinforced structure is subjected to fire, all elements including substrate material, CFRP, adhesive are

simultaneously affected by elevated temperature and mechanical load. In Eurocode, the ultimate strengths and

Young’s modulus of concrete and steel are described to be reduced as the temperature rises. Recent research efforts

have also deepened the knowledge about the performance of CFRP and adhesive. The remained question is how

to combine these elements efficiently. Some recent researches separately focus on the fire performance of CFRP

reinforced structure using EBR or NSM method but the comparison between these methods is not yet investigated.

Therefore, the aim of this study is to identify the thermo-mechanical performance of CFRP reinforced concrete

structure with two reinforcement methods: EBR and NSM. In this study, the concrete structure is reinforced with

a pultruded laminate CFRP using a two-component epoxy. The studied structure is first applied with a pre-defined

mechanical load, and then the temperature surrounding the sample increases with the heat rate at 30C/minute

until rupture of the studied structure. The rupture temperature and the effect of the thermal exposure duration on

behaviour of the studied structure at different cases are then analysed to identify the performance of the structure.

The results show that with the used adhesive, the CFRP reinforced concrete structure has better performance in

thermo-mechanical condition when using the NSM method (compares to the EBR method). The NSM structure

can resist up to temperature at 4 times higher than that of the EBR structure at the same shear stress. It is also

shown that with the rise of the mechanical loading, the resistible temperature of the studied structure decreases

with the rate of decrease depending on reinforcement method. The failure mode of the tested structures show that

with the NSM method, both the CFRP, the adhesive and the concrete were simultaneously affected while with the

EBR method, only the adhesive were damaged due to shear stress.



282


(a) (b)

Figure 1:

(a) Thermomechanical machine used for the tests on CFRP reinforced concrete structures

(b) Failure modes of the CFRP reinforced concrete structures using two reinforcement methods [externally

bonding reinforcement (EBR) and near surface mounted (NSM)]

ACKNOWLEDGMENTS

This research has been performed with the financial support of the LMC2 (thanks to its industrial projects) for the experimental works. This research has also been realized with the financial support of a doctoral scholarship from the Ministry of Education and Training of Vietnam. We would like to thank the team of technicians (Mr E. JANIN and Mr N. COTTET) from the Civil Engineering department of the IUT Lyon 1 and the LMC2, University Lyon 1 for their technical support.



283


MESOSCALE MODELING OF THE ELEVATED TEMPERATURE BEHAVIOR OF

THE BASALT TEXTILE REINFORCED CONCRETE

Manh Tien TRAN1,2, Xuan Hong VU1, Emmanuel FERRIER1 1 Université de Lyon, Université Lyon 1, Laboratory of Composite Materials for Construction (LMC2), 82 bd


lyon1.fr, [email protected] 2 Hanoi University of Mining and Geology (HUMG), Department of Material Resistance, 18 Pho Vien, Bac Tu

Liem, Hanoi, Vietnam

KEYWORDS

Textile-reinforced concrete (TRC), numerical study, mesoscale modelling, basalt, elevated temperature, thermo-

mechanical behavior, residual behavior

ABSTRACT:

The textile reinforced concrete (TRC) can be used for the reparation and the reinforcement of civil engineering

works. There were several studies on the behavior of the textile reinforced concrete (TRC) subjected to residual

and thermomechanical loading. Most of the previous studies concern the experiments in which direct tensile tests

were carried out to characterize the residual and thermomechanical behavior of TRC. The experimental data of the

residual and thermomechanical behavior (at elevated temperature) of the basalt textile reinforced calcium

aluminate concrete were available and obtained by other researchers in a previous study.

This paper presents a mesoscale modeling of the elevated temperature behavior of the basalt textile reinforced

concrete. The ANSYS MECHANICAL software was used in this numerical study. A two-dimension (2-D) finite

element model was constructed using the PLAN183 element (two-dimension (2-D), 8 nodes, structural solid

element) for the cementitious matrix and the basalt fiber. The cohesive element INTER203 (two-dimension (2-D),

6 nodes, cohesive element) was used for the interface between the basalt fiber and the matrix. This model gave

interesting numerical results that were in agreement with the available experimental data.

From the principal characteristics of the constituent materials (the basalt fibre, the matrix and the fibre/matrix

interface) (input data), the proposed mesoscale model allowed to numerically obtain, with little difference in

comparison with the available experimental data, the “stress – strain” relationship of the TRC and the principal

characteristics of the TRC (as ultimate strengths and strains, strengths and strains at typical points, Young’s

modulus) when the TRC was subjected to different temperatures (25°C, 75°C, 150°C, 200°C). Furthermore, a

parametric study showed a significant influence of the basalt textile reinforcement ratio on the ultimate strength

of the TRC. The increase of the ultimate strength of TRC with the basalt textile reinforcement ratio, for different

temperatures, was successfully simulated. The numerical results of this study show that the mesoscale modeling

allows to predict the TRC behavior at elevated temperature. The successful mesoscale finite element modeling of

TRC provides an economic and alternative solution in comparison with expensive experimental investigations.



284


(a)

(b) (c)

Figure 1 : (a) Configuration of the matrix, fibre and interface elements of the TRC in the 2-D mesoscale model

(ANSYS).

(b,c) Stress/strain relationship of the basalt textile reinforced concrete subjected to different temperatures [25°C

(b), 150°C (c)] : mesoscale modeling versus experimental results (*RAMBO et al, 2015, Cem. Concr. Compos.,

vol. 70, 2016)

ACKNOWLEDGMENTS

This research has been performed with the financial support of the LMC2 (thanks to its industrial projects) for the

experimental works. This research has also been realized with the financial support of a doctoral scholarship from

the Ministry of Education and Training of Vietnam. We would like to thank the team of technicians of the Civil

Engineering Department of the IUT Lyon 1, University Lyon 1 for their technical support.



285


FIRE BEHAVIOUR OF GFRP-REINFORCED CONCRETE SLAB STRIPS: FIRE

RESISTANCE TESTS AND NUMERICAL MODELLING

Inês C. Rosa1, João P. Firmo1,2, Carolina Churro1, Pedro Santos1, Mário R. T. Arruda, João R. Correia 1 1 CERIS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; 2 Corresponding author:

[email protected]

KEYWORDS:

Experimental study; Modeling; Fire, impact and blast loading; Temperature; FRP internal reinforcement;

ABSTRACT:

This paper presents experimental and numerical investigations on the fire behaviour of concrete slab strips

reinforced with sand-coated glass fibre reinforced polymer (GFRP) bars. The experimental programme comprised

fire resistance tests on a reference steel-reinforced concrete (RC) slab strip and on four GFRP-RC slab strips; all

specimens were simultaneously subjected to the ISO 834 standard fire (using an intermediate scale furnace) and a

sustained service load applied in a 4-point bending configuration. The influence of the following parameters on

the fire resistance of the slab strips was assessed: (i) the concrete cover thickness (25 mm or 35 mm); (ii) the

presence of cold anchorages in the GFRP rebars, and (iii) the presence of lap-splices in the fire-exposed length of

the slabs (lengths of 30 cm and 60 cm). The results obtained show that considerably long periods of fire resistance

can be attained in slabs with GFRP reinforcement provided that the anchorage zones of the rebars remain

sufficiently cold; in fact, the slab strips reinforced with continuous rebars and 25 mm and 35 mm of concrete cover

failed after 148 min and 158 min of fire exposure, respectively. For the slab strips with bar splices exposed to heat,

the fire resistance was reduced to less than 20 min, showing that this constructive detail has a significant impact

on the fire performance of GFRP-RC members. The numerical study comprised the development of 3D non-linear

finite element thermo-mechanical models to simulate the fire response of the reference steel-RC slab strip and of

the RC slab strip reinforced with continuous GFRP bars. At this stage, the bond vs. slip behaviour of the GFRP

rebars as a function of temperature was not considered (perfect adherence). In any case, these preliminary models

provided accurate predictions of the thermo-mechanical response of the tested specimens, namely in terms of

temperatures and midspan deflection increase with time of fire exposure.

Figure 1: Fire resistance tests setup: (a) general view; (b) longitudinal and (c) transversal scheme of the test

setup and thermal insulation system.

Slab

Furnace

(ISO 834)

Weights

Load

transmission

beam

Insulation

system

Reaction frame

Sliding

support

Fixed

support

a)

Furn

ace

wall

s

Furn

ace

wall

s

0.800.20 0.20

Dimensions in [m]

c)

Slab strip

Ceramic wool

Isolation modulus

Furnace interior

(side view)

0.95

0.467 0.4670.467P P

Furn

ace

wall

s

0.05 0.05

Furn

ace

wall

s

0.20 0.20

b)

1.10

Ceramic wool

0.25

0.11



286


FIBRE-REINFORCED INTUMESCENT COATINGS AS A FIRE-SAFE CONFINING

MATERIAL FOR CONCRETE COLUMNS

Zafiris Triantafyllidis 1 and Luke Bisby 1 1 The University of Edinburgh, Institute for Infrastructure and Environment, Edinburgh, United Kingdom


KEYWORDS :

Strengthening and repair; New composite materials, systems and strengthening techniques; Fibre-reinforced

intumescent coatings; Concrete column strengthening; Confinement; Fire protection.

ABSTRACT:

A serious concern associated with the use of fibre-reinforced polymer (FRP) materials in structural strengthening

is their comparatively poor mechanical performance at the elevated temperatures that would be experienced in a

fire. In many cases, supplemental passive fire protection (PFP) systems must be installed on the exterior of FRP

strengthening schemes such that the strengthened structural elements can achieve the required fire resistance

ratings, often leading to substantially increased installation costs and disruption in operational buildings. This

paper presents a novel application of fibre-reinforced intumescent coatings (FRICs), as an alternative material

system for strengthening and fire protecting damaged or deficient concrete columns. Carbon fibre-reinforced

epoxy-based intumescent coatings are PFP systems that are extensively used to protect structural steel elements

from the potentially catastrophic effects of fire in the oil and gas or high value infrastructure markets. These

systems are typically reinforced with continuous fibre meshes; thus, under normal service temperature conditions

(i.e. prior to a fire event), the intumescent coatings are effectively fibre-reinforced polymer coatings. This paper

demonstrates that FRICs with suitably modified fibre contents and mesh architectures can be used to provide

inherently fire-safe strengthening or retrofitting of concrete columns, by providing confinement to the concrete

core at ambient temperature in addition to protecting them in fire. The results of an experimental program studying

the ambient temperature uniaxial compressive behaviour of plain concrete cylinders that are laterally confined

with the novel FRIC system are presented. It is clearly demonstrated that the confining effectiveness of the novel

composite fire protection system at ambient temperature is at least as good as that of conventional non-intumescent

FRP wraps comprising the same carbon fibre mesh reinforcement, thus proving the strong potential of FRICs as

alternative strengthening systems for concrete columns, particularly in applications where structural fire resistance

is required.

(a)

(b)

Figure 1: (a) Concrete cylinders confined with a carbon fibre-reinforced intumescent wrap; (b) typical uniaxial

stress versus strain responses obtained for specimens strengthened with FRICs.

0

10

20

30

40

50

60

-0.025 -0.015 -0.005 0.005 0.015 0.025

Axi

al S

tress (M

Pa)

Strain

Unwrapped

Mesh1

3x Mesh1

PBO Mesh

UD FabricHoop Axial




287


EXPERIMENTAL AND ANALYTICAL ANALYSIS OF THE THERMOMECANICAL

BEHAVIOUR AT ELEVATED TEMPERATURE OF THE TEXTILE REINFORCED

CONCRETE (TRC): EFFECT OF THE HYDRIC STATE OF TRC

Mohamed SAIDI, Xuan Hong VU, Emmanuel FERRIER

Université de Lyon, Université Lyon 1, Laboratory of Composite Materials for Construction (LMC2), 82 bd


lyon1.fr, [email protected]

KEYWORDS :

Thermomechanical behavior, elevated temperature, textile-mortar composite, Textile Reinforced Concrete

(TRC), moisture state, saturation degree, cementitious matrix, alkali-resistant glass textile, analytical modeling

ABSTRACT:

In recent decades, Textile Reinforced Concrete (TRC) materials have become increasingly used to repair and/or

reinforce civil engineering structures thanks to their various advantages (non-toxicity, availability of raw materials,

recyclability, ease of implementation ...). However, the elevated temperature behavior of these materials has not

been much studied.

The purpose of this study is to investigate the influence of the TRC's hydric state on its thermomechanical behavior

under combined thermal and mechanical loading. The studied TRC was made with a refractory cementitious matrix

and three layers of continuous alkali-resistant glass textiles. In this study, two hydric states of the same TRC were

studied: the “almost dried” state and the saturated one. The “almost dried” TRC samples were stored in the oven

at 50°C until the stability of the mass (TRC’s water content of about 3.82%) and the saturated TRC samples were

emerged in water until the stability of the mass (TRC’s water content of about 14.18%). Thanks to a new

experimental approach of the thermomechanical testing and a careful control of the TRC hydric state, this study

allowed identifying the thermomechanical tensile behavior of the “almost dried” TRC and of the saturated one

subjected to different temperatures (varying from 20°C to 800°C). This study also allowed understanding the role

and influence of the hydric state of the cementitious matrix on the thermomechanical behavior of the TRC.

The results of this study showed that the TRC hydric state influences its thermomechanical properties due to the

effect of interstitial pressure, especially at temperature levels below 300°C, on the cementitious matrix or on the

glass fibre-matrix interface. The transfer of charge between the fibre and the matrix is also influenced by the TRC

hydric state. Generally, the more the TRC is wet, the more the thermomechanical characteristics of the TRC

(ultimate stress, ultimate strain and Young’s modulus) decrease.

The experimental work of this study is followed by an analytical analysis which aims to calibrate existing analytical

Gibson model that was used to describe the behavior of polymer matrix composite materials as a function of

temperature. On the basis of a modification of the Gibson model and the obtained experimental results, the various

parameters were identified, analyzed and adapted with the taking into account of the hydric states (“almost dried”,

“saturated”, water content of 8%) of the TRC.



288


Figure 1:

(a) Control of the TRC hydric state before the test : "almost dried" TRC conserved in the oven at 50°C,

"saturated" TRC conserved in water; (b) Used thermomechanical machine; (c) Evolution of the ultimate stress

of the ‘‘almost dried’’ TRC and of the ‘‘saturated’’ TRC according to temperature

ACKNOWLEDGMENTS

This research was performed with the financial subvention of the European Regional Development Fund of the

European Union and of the Rhône-Alpes-Auvergne region, France for the lot 5 “Characterization of composite

materials” of the PRORETEX II research project. This project is the collaborative research project between four

industrial partners (SULITEC - project leader; FOTIA; ER2I; CIMEO) and two academic partners (UCBL/LMC2;

ENISE/LTDS). We also would like to thank the team of technicians (Mr. Emmanuel JANIN, Mr. Nobert

COTTET) from the Civil Engineering Department at IUT Lyon 1 and LMC2, University Lyon 1 for their technical

support.

(a)

(b) (c)

"Almost dried" TRC stored in the

oven at 50°C

"Saturated" TRC conserved in

water



289


TWO-DIMENSIONAL MODELING OF THERMO-MECHANICAL RESPONSES OF

GFRP BOX BEAM SUBJECTED TO ISO-834 FIRE

Lingfeng Zhang1, Lu Wang 2, Weiqing Liu 3* 1 School of Civil Engineering, Southeast University, Nanjing, China; 2 College of Civil Engineering, Nanjing

Tech University, Nanjing, China; 3 Advanced Engineering Composites Research Center, Nanjing Tech

University, Nanjing, China ([email protected])

KEYWORDS :

Fiber reinforced polymers; Modeling ; Thermo-mechanical responses; Alternating direction implicit (ADI)

Add one or two own keywords if needed

ABSTRACT:

During the past three decades, one-dimensional (1-D) heat transfer model was frequently used to estimate the

thermal responses of glass fibre-reinforced polymer (GFRP) materials and structures. However, in real fire

scenarios, beams and columns are usually subjected to multi-side fire loading, and the whole cross-sectional

thermal responses can hardly be obtained when using a 1-D model. To address this issue, a 1-D model was

extended to a two-dimensional (2-D) model to predict the thermo-mechanical responses of GFRP box beam

subjected to one-side ISO-834 fire exposure and four-point bending. The 2-D governing heat transfer equations

with thermal boundary conditions, discretized by alternating direction implicit (ADI) method, were solved by

Gauss-Seidel iterative approach. Based on beam theory, the mechanical responses were obtained by the

temperature-dependent Young’s modulus. The model was validated by comparing the simulated results and the

available experimental data of the beam. Both temperatures and mid-span deflections of the GFRP box beam in

the experiment can reasonably be predicted by this model.

Figure 1 : Flowchart of 2-D solution process

WebWebq=0 q=0

Convection and radiation

ISO-834 fire

Convection

and radiation

q=0

q=0

T,f

q

q=0

q=0

T,f

q=0

T,f

q=0

q

q=0

q

q

q=0

q

q

q=0

qq

q

q

Top flange

Bottom flange

2-D thermal responses2-D mechanical responses

GFRP box beam

Simplify

Mesh

Beam theory

Chemical

kinetics

ADI techniques

ADI differential formats



290


STRUCTURAL BEHAVIOR OF CFRP CONFINED RC BRIDGE BENT UNDER

IMPACT LOADING

Charles Plante1, Nathalie Roy1, Charles-Philippe Lamarche1, François Settecasi1 1 University of Sherbrooke, Civil engineering department, Sherbrooke, Canada

KEYWORDS :

Strengthening and repair; Modeling ; Characterization of FRP and FRC materials/systems; Durability, long-

term performance

ABSTRACT:

In the United States of America, from 1989 to 2000, 11,7% of all bridges failures were caused by impact loads

which is the second most important cause after those related to flooding. Over the past decade, only a few studies

have been carried out on impact loading on bridges and North American standards seem insufficiently detailed to

provide adequate design. Solutions to prevent and to repair damages caused by vehicles collisions on bridge piers

are currently studied. One of them is to confine the piers with carbon fibre reinforced polymer (CFRP) jackets.

The purpose of this research is to determine the effects of the CFRP jacket on RC bridge bent structural behaviour

when the columns are previously damaged by impact load. To that end, dynamic laboratory tests are performed

on both confined and unconfined RC bridge columns. Test specimens consist of two columns bridge bent (1:6

scale). When submitted to successive impacts loads, laboratory tests show that the bridge bent suffers less damages

when the columns are confined with a CFRP jacket. That affirmation is still true even if the bridge bent has been

previously damaged by an impact load prior to the CFRP jacket being installed.

The structural performance of the bridge bents is greatly improved by the confinement. The comparison is made

by analysing the limit states of different piers with and without confinement. Detailed testing procedure and

numerical results will be presented in the paper.

Figure 11 – Test setup



291


TEMPERATURE EFFECT ON THE BOND BEHAVIOUR OF A TRANSVERSELY

COMPRESSED MECHANICAL ANCHORAGE SYSTEM

Luis Correia1, Cristina Barris2, José Sena-Cruz3 1 University of Minho, ISISE, Dept. of Civil Engineering, Guimarães, Portugal;2 University of Girona, AMADE,

Dept. of Mech. Engineering and Industrial Construction, Girona, Spain; 3 University of Minho, ISISE, Dept. of

Civil Engineering, Guimarães, Portugal (corresponding author: [email protected])

KEYWORDS :

All FRP and smart FRP structures; Temperature ; Bond and interfacial stresses; Durability, long-term

performance; transverse compression; CFRP; EBR

ABSTRACT:

Nowadays the strengthening of reinforced concrete (RC) structures using FRP composites is a viable reality, consolidated

by many studies and practical applications. One of the most common methods used to apply the FRP is the externally

bonded reinforcement (EBR) technique. However, the development of stresses at the anchorage zones of the EBR-FRP

composite might cause premature debonding. To delay or avoid premature failure, mechanical systems were successfully

developed.

Figure 12: Top view and side view of the test set-up and instrumentation.

This works aims to assess the performance of a mechanical system: the metallic anchorage plate commercially distributed

by S&P Clever Reinforcement Company. For that purpose, an experimental program composed by twenty-two concrete

blocks (200x500x800mm3) strengthened with EBR-CFRP laminates mechanically anchored to the concrete is presented.

Each metallic plate is fixed to the concrete element through six prestressed bolts, creating a confinement distribution of

stresses in the anchorage region. All specimens were tested up to failure under two types of pull-out configurations: the

steady-state temperature, where the laminate is pulled from the block with increasing force and constant temperature (20ºC,

60ºC and 80ºC); and the transient temperature, where the laminate is pulled with constant force (0,4%, 0,5% and 0,6% of

strain) and the temperature is gradually increased. Besides temperature and test configuration, the influence of the laminate

width and level of transverse compression in the metallic plate were also studied. Results showed that the debonding process

and failure are highly influenced by the temperature, laminate width and confinement level.




292


Figure 13: Main results of the experimental campaign (steady-state temperature).



293


NUMERICAL SIMULATIONS OF GFRP-RC SLABS IN FIRE

Antonio Bilotta1, Alberto Compagnone1, Emidio Nigro1 1 Department of Structures for Engineering and Architecture - University of Naples Federico II, Italy

(Corresponding author: [email protected]

KEYWORDS :

All FRP and smart FRP structures; Modeling ; Fire, impact and blast loading; Codes, standards and design

guidelines

ABSTRACT:

Fire is one of the most serious potential risks for buildings and structures, and for this reason international codes

provide specific guidelines to take account of fire in the design of structures. Among construction materials, the

concrete is generally characterized by acceptable performance in fire. Indeed, the material can protect itself by

fire, thanks to its low thermal conductivity, and protects the internal reinforcements used for reinforced concrete

(RC) members. Both traditional steel bars and more recently developed fibre reinforced plastic (FRP) bars, benefit

from the protection of concrete. In this framework, some authors of this paper performed experimental flexural

tests and developed theoretical interpretative models about bending moment resistance of FRP-RC slabs.

Nevertheless, the real behaviour of structural elements can therefore be very different from that indicated by

standard furnace tests and should be investigated, as is usual within the Fire Safety Engineering approach .In order

to extend the results of experimental tests to different cases, using a numerical model the paper shows the

preliminary results of some numerical simulations of GFRP-RC slabs at ambient condition and in fire conditions,

focusing on some modelling aspects which can improve efficiency of calculus. The numerical investigation

highlights that the simplified model for the concrete in tension allows good estimations of displacements and

stresses in fire condition. The model will be used to perform extensive numerical analyses by varying mechanical

and geometrical properties and compare the results with the predictions of analytical methods, also including the

effect of the concrete spalling.



294


MULTIPHYSICS INVESTIGATIONS INTO NSM CFRP AT ELEVATED

TEMPERATURES

Thushara Siriwardanage 1 and Yail J. Kim 2

1 Department of Civil Engineering, University of Colorado Denver, USA 2 Department of Civil Engineering, University of Colorado Denver, USA, Email: [email protected]

KEYWORDS

Carbon fiber reinforced polymer (CFRP), modeling, multiphysics, near-surface mounted (NSM).

ABSTRACT

This paper presents the interfacial behavior between near-surface mounted (NSM) carbon fiber reinforced polymer

(CFRP) strips and a concrete substrate, bonded by an epoxy adhesive. The first part of research discusses an

experimental program focusing on the temperature-dependent strength of the bonding agent, and the load-

displacement and load-carrying capacity of the CFRP-concrete interface. The second component is concerned with

developing a multiphysics model that consists of thermal and mechanical simulations. Investigation results reveal

that thermal distress significantly affects the strength of the bonding agent with an increasing level of uncertainty

and controls the response of the interface. Good agreement is made between the test data and model prediction in

terms of capacity reduction and failure mode.

(a) control specimen (b) thermally-loaded specimen

Figure 1: CFRP-concrete interface testing



295


Practical applications



296


NDT SIGNAL ANALYSIS OF CFRP-LAMINATE BOND ON RC BRIDGES

Kenneth C. Crawford

Institute for Bridge Reinforcement and Rehabilitation, Bloomington, Indiana USA

KEYWORDS:

CFRP Bond, non-destructive testing, impact-echo, bridges

ABSTRACT:

The purpose of this paper is to present on-going research in non-destructive testing (NDT) of carbon-fiber

reinforced polymer (CFRP) laminate plate bond in FRP structural systems applied to reinforced concrete (RC)

highway bridges. Using the NDT impact-echo principle a light mobile impact machine made with a 3D-printed

polylactide plastic frame produces multiple acoustic (low frequency) signals per meter of CFRP plate bonded to

RC-bridge structural members. Each impact produces a specific signal waveform signature defined by the CFRP-

plate concrete bond condition. A change in plate bond to a de-bonded condition produces a uniquely different

waveform signature. The impact waveforms are characterized by exponentially decaying sinusoids with differing

decay rates, times, frequencies, and amplitudes. These waveform differences markedly identify changes in CFRP-

plate bond condition. Signal analysis of recorded impact waveform signals provides a visual profile and a digital

data base record of bond conditions across the length of the CFRP plate. The objective of the NDT impact

procedure presented in this paper is to evaluate (test) long lengths CFRP plates bonded to highway bridges. This

objective is driven, in part, by a requirement to evaluate a number of CFRP-strengthened bridges in the Republic

of Macedonia to determine plate bond condition 17 years after installation. The paper presents results of recent

field testing with the impact procedure on existing FRP-strengthened highway bridges in the State of Missouri

using a mobile impact machine. Test results are compiled to show bond conditions over the length of the FRP

applications. Successful development and application of this NDT impact procedure will provide bridge engineers

an effective field protocol (tool) for long-term testing of CFRP-structural systems applied to multiple highway

bridges in a national highway system. With periodic testing the impact waveform data base will establish a record

for FRP-system bond behaviour over time on RC highway bridges.



297


I75 BRIDGE OVER SEXTON/KILFOIL DRAIN, THE LONGEST HIGHWAY BRIDGE

SPAN PRESTRESSED WITH CFRP STRANDS

Nabil Grace1,4, Matthew Chynoweth2, Tsuyoshi Enomoto3, Mena Bebawy1 1 Lawrence Technological University, Southfield, MI, U.S.A.; 2 Michigan Department of Transportation,

Lansing, MI, U.S.A.; 3 Tokyo Rope USA Inc., Canton, MI, U.S.A.; 4 (corresponding author: [email protected])

KEYWORDS :

Highway bridge ...; Prestressing CFRP ... ; Field test ...; Bridge design ...

ABSTRACT:

Extensive experimental, analytical, and numerical research efforts resulted in the design and construction of the

longest highway bridge span prestressed with carbon fiber reinforced polymer (CFRP) strands. This 42-m-long

simply-supported bulb-T beam bridge carries I-75 highway over Sexton/Kilfoil Drain in Allen Park, Michigan,

U.S.A. The bridge superstructure is composed of ten 1.83-m-deep bulb T beams supporting a 23-cm-thick

reinforced concrete deck slab. One exterior beam is prestressed with a total of 67 CFRP strands, while the rest of

the beams are prestressed with a total of 63 strands each. Each strand is tensioned with an initial prestressing force

of 156 kN, which represents approximately 65 % of the strand guaranteed strength.

To ensure the safety and adequacy of the bridge to carry the assigned traffic loads and withstand the

severe weather in Michigan, the design of the bridge underwent multiple revisions and test results from a parallel

experimental investigation were utilized to make key design decisions. Design aspects such as creep rupture and

relaxation of CFRP, effect of freezing and thawing cycles, mode of failure, and appropriate environmental and

strength reduction factors were all taken into consideration.

Handling of CFRP strands and construction of the beams also required extra care and special training.

For instance, prestressing the strands was executed by coupling the CFRP strands to conventional low-relaxation

steel strands at both ends to eliminate the need for special anchorage systems. Prestress loss from the time of

prestressing to the time of prestress release was affected by the nature of CFRP but it was properly evaluated and

included in the design.

After construction and before opening for traffic, several bridge beams were instrumented with strain and

deflection sensors and a field load test using two trucks positioned at strategic locations on the bridge was executed.

The strain and deflection of the beams due to the truck loads were captured and analysed to ensure adequate

performance.

Figure 1 : Construction of I-75 bridge over Sexton/Kilfoil Drain in Allen Park, MI, U.S.A.



298


REPAIR OF PANAMA'S 50-YEAR-OLD BRIDGE WITH CFRP RODS

Julien Mercier1, Vanessa Buchin1, Christian Tourneur 1, Guillermo Medina2 1 Freyssinet International, Technical Department, Rueil-Malmaison, France; 2 Freyssinet de Mexico Tierra

Armada S.A. ([email protected])

KEYWORDS:

Strengthening and repair; Case studies ; FRP internal reinforcement; Characterization of FRP and FRC

materials/systems; CFRP rods; NSM Technic

ABSTRACT:

Freyssinet performed important repair work in 2015 on Panama's 50-year-old Bridge of the Americas. It’s a steel

truss arch bridge built between 1959 and 1962, 1654m long with 14 sections with a main section 344m long. The

concrete slab had to be reinforced because of load evolution of road rules.

The initial project was a reinforcement with additional metallic rebars, representing 222 tons of rebars. Such rebars

would be embedded above the existing rebars and would not respect the minimum coating thickness for corrosion

protection.

Furthermore, an important traffic on this motorway required the work to be performed in a short time during the

night.

A very efficient solution was proposed and applied by Freyssinet. Reinforcement with CFRP rods embedded into

the concrete cover and sealed with resin (NSM technic). Thus, the equivalent weight of carbon rods was 12 tons,

which consequently reduced the weight to be transported and to be installed. An additional reinforcement of the

underside of the bridge was performed with CFRP Foreva TFC solution.

The working time was limited and the traffic has to be reopened on sealing resin not completely hardened.

Preliminary mechanical tests have been performed to evaluate the evolution of anchoring capacity during the first

8 hours of polymerization of resin. It was demonstrated that anchoring capacity was sufficient after a minimum of

5 hours at 20°C or 3 hours at 35°C after resin application.

The CFRP quantities applied were very important: 64 000 meters of carbon rods (12mm diameter) in grooves and

45 000m² of Foreva TFC fabric under the slab.

Thus specific methods and equipment were developed for this special applications. Cutting machine with several

special diamond discs for concrete grooving operation; automatic pump and melting nozzle for resin application.

The efficiency was clearly improved, around 35meters/h.

https://structurae.net/structures/bridges-and-viaducts/truss-arch-bridges


Composites


299


Figure 1: Anchoring test of carbon rod into resin groove

Figure 2: View of the bridge and different stages of reinforcement



300


PERFORMANCE STUDY OF A POST-TENSIONED CONCRETE SLAB

STRENGTHENED WITH CFRP USING 24 HR AND CYCLIC LOAD TESTING

Thanongsak Imjai 1, Burachat Chatveera 2 and Udomvit Chaisakulkiet 3 1 Dept. of Civil Engineering, Rajamangala University of Technology Tawan-Ok, Bangkok, Thailand; (Email:

[email protected]) 2 Dept. of Civil Engineering, Thammasat University, Bangkok, Thailand; 3 Dept. of Civil Engineering, Rajamangala University of Technology Rattanakosin, Bangkok, Thailand;

KEYWORDS :

Strengthening and repair; Structural assessment ; Post-tensioned slab; EBR; Load tests

ABSTRACT:

This article presents the showcase on a performance study of post-tensioned concrete slabs using externally bonded

carbon fibre reinforced composites (CFRP). The concrete slabs are part of a full-scale 17 storey building located

in in Thailand. The original building (completed in 2000) is currently used as the residential building. Design

verifications based on ACI 318 indicated that the flexural capacity of the original post-tensioned slab was

insufficient to resist the new superimposed loads from three water tanks with capacity of 1000 litres that is planned

to install on the roof top floor. Conversely, flexural, shear and torsional capacity of the existing RC beam and

column sections were sufficient to resist the superimposed loads by up to 120% (under the roof top level). As part

of the retrofitting programme, the concrete slab was strengthened with Carbon FRP (CFRP) laminates using a

manual lay-up application. The load capacity and deflection of the FRP-strengthened slab was then re-assessed

according to the 24 hours (ACI-318) and cyclic load (ACI-437) test protocols. Based on the floor load test results,

it was found that the proposed strengthening solution was adequate to sustain the increased load demand imposed

by the water tanks.

Figure 1 : Application of EBR CFRP strengthening on post-tensioned concrete slab

EBR strengthening Overview of the 17 stories hotel



301


DESIGN AND CONSTRUCTION OF A HYBRID DOUBLE-SKIN TUBULAR ARCH

BRIDGE

Leo de Waal1, Shuan Jiang1, Juan Torres1, Guang-Ming Chen2, Jin-Guang Teng3, Paul Rodman4, Peter Burnton5,

Dilum Fernando1,*

1The University of Queensland, School of Civil Engineering, Australia, *Email: [email protected]

2Guangdong University of Technology, School of Civil and Transportation Engineering, China

3The Hong Kong Polytechnic University, Department of Civil and Environmental Engineering, China

4Rocket C Pty Ltd, Brisbane Australia

5Arup Pty Ltd, Brisbane, Australia

KEYWORDS

Double-skin tubular arch bridge; bridge design; bridge fabrication; GFRP joints

ABSTRACT

A novel double-skin tubular arch (DSTA) bridge system is being developed at the University of Queensland as a

collaborative effort of several organizations. This new bridge system builds on the existing research on hybrid

double-skin tubular members (DSTMs) which consist of an outer FRP tube, an inner steel tube and a layer of

concrete sandwiched between them. DSTA bridges are light-weight, durable, of low-cost and rapid to construct,

thus providing a highly attractive alternative to traditional bridge systems. This paper presents the design and

construction of a full-scale DSTA bridge prototype (Figures 1, 2) in the laboratory. The design procedure based

on existing design provisions for DSTCs is briefly presented. The construction process of the DSTA bridge,

including the fabrication of steel and GFRP segments, assembly process, fabrication of joints and concrete casting,

is described in detail and discussed. Two methods for the fabrication of GFRP joints, namely the wet-layup process

and the pre-preg process, are described and compared.

Figure 1: DSTA bridge constructed at UQ. Figure 2: (a) DSTA details, (b) DSTB details.



302


DISTRIBUTED OPTICAL FIBRE SENSORS TO MONITOR PRESTRESSED

CONCRETE BRIDGE BEAM STRENGTHENED WITH BONDED FRP

Aghiad Khadour1, Marc Quiertant1, Gonzague Six1, Corentin Le Roy2, Christophe Aubagnac2 1Ifsttar, Champs-sur-Marne, France ; 2Cerema, Centre Est, Autun, France


KEYWORDS :

Distributed optical fibre sensors; Experimental study; Bond and interfacial stresses; Strengthening with bonded

FRP

ABSTRACT:

The mechanical behaviour of large scale pre-stressed concrete beam strengthened with adhesively bonded FRP

was studied; using distributed optical fibre sensing technique. The sensing fibres were installed into concrete

structure and between FRP layers.

The high spatial resolution strain measurements leads to measure precisely the strain profile along the strengthened

beam and to identify the pre-existing cracks and the new cracks which appeared during the 3 points bending test

carried-out in 2014, and during shear test performed to the half of the beam in 2016. The role of FRP layers for

strengthening and for the control of the crack openings was possible using the different fibres between the FRP

layers.

Figure 1 : Strain profile obtained during shear loading steps (spatial resolution: 1 cm; measurement incertitude:

4 microstrain)

0 1 2 3 4 5 6 7 8

0

50

100

150

200

250

300

Str

ain

(m

icro

stra

in)

L (m)

01-200kN

02-300kN

03-400kN

04-500kN

05-600kN

06-700kN

07-800kN

08-900kN

09-1000kN



303


DEVELOPMENT OF A MODULAR FOOTBRIDGE WITH PRE-TENSIONED CFRP

REINFORCEMENT – PRE-DESIGN AND DIMENSIONING OF BOND

ANCHORAGE ZONE

Sophia Perse1, Christian Knorrek1, Norbert Will 1, Josef Hegger 1 1 Institute of Structural Concrete, RWTH Aachen University, Aachen, Germany


KEYWORDS :

All FRP and smart FRP structures; Experimental study; Bond and interfacial stresses

ABSTRACT:

a common problem of concrete bridges are corrosion damages of the steel reinforcement. the related loss of

capacity as well as visual effects require often expensive and labor-intensive refurbishment or even reconstruction.

to overcome these drawbacks, a modular footbridge system without steel reinforcement is developed. the

application of non-corrosive carbon fiber reinforced polymer (cfrp) reinforcement is suitable for building slender

constructions, which are durable and long-lasting. for the elements of the modular bridge system cfrp

reinforcement is applied as mesh fabrics and pre-tensioned rebars. to enhance durability and reduce costs a high

strength concrete (hsc) with high density is applied. for an economic and safe design of the superstructure, the

behavior of cfrp members in hsc has to be investigated. the dimensions of the bond anchorage zone determine the

web widths since a minimum concrete cover has to be provided to avoid splitting cracks in the transmission zone.

in a first step, small scale beam tests are carried out to investigate the required minimum concrete cover and tendon

spacing. furthermore, the transfer lengths are determined in these tests. with the information of bond tests, the final

cross section of the modular footbridge is defined. following, experimental and theoretical investigations on t-

beams pre-tensioned with cfrp tendons will be conducted to develop the footbridge system.



304


COMPOSITE RAILWAY SLEEPERS – NEW DEVELOPMENTS AND

OPPORTUNITIES

Allan Manalo1, Peter Schubel1 and Wahid Ferdous2 1Centre for Future Materials, School of Civil Engineering and Surveying, University of Southern Queensland,

Toowoomba, Queensland 4350, Australia ([email protected]) 2Department of Civil Engineering, Monash University, Australia

KEYWORDS :

All FRP and smart FRP structures; Case studies ; Characterization of FRP and FRC materials/systems; Codes,

standards and design guidelines ; Composite Sleepers; Railways.

ABSTRACT:

During the last few years, the Centre for Future Materials at the University of Southern Queensland (USQ) in

collaboration with different railway industries in Australia, has dedicated significant research effort to develop

innovative composite railway sleeper technologies. These sleepers are engineered to mimic the behaviour of

structural timber, which is very important in the maintenance of deteriorating timber sleepers including existing

timber lines, turnouts and transoms. This paper aims to present the recent developments on composite sleepers and

new opportunities for their wide acceptance and use.

The timber replacement sleeper made of sandwich composites with epoxy-based polymer coating was specifically

designed to conform to the loading conditions for mainline application wherein the sleeper is only loaded in two

distinct locations (at the rails) and does not need the same strength along its length. This results in a sleeper

technology that requires significantly less volume of material while still complying with all strength and stiffness

requirements of a timber sleeper (Fig. 1 - left). The novel shape of this sleeper offers significantly increased

resistance against lateral movement (particularly important in curved track). Fifty units of this new sleeper have

been installed and under service in the standard railway line in Australia on the Queensland Rail Line.

Another composite sleeper technology developed are sleepers for railway turnout and transoms. These sleepers

have a prismatic rectangular shape (Fig. 1 - right) and contain long glass reinforcement fibres in both the

longitudinal and transverse directions. By strategically orienting the sandwich composites where they are most

effective in carrying the bending moment and shear forces, the total amount of materials used are significantly

reduced. Twenty two of these transoms were installed by Australian Rail Track Corporation (ARTC) on a railway

bridge in the Hunter Valley, Australia.

Figure 1. Timber replacement sleeper (left) and composite transom sleepers (right)




305


NDT SIGNAL ANALYSIS OF CFRP- BOND ON RC BRIDGES LAMINATE

Kenneth C. Crawford

Institute for Bridge Reinforcement and Rehabilitation, Bloomington, Indiana USA

KEYWORDS:

CFRP Bond, non-destructive testing, impact-echo, bridges

ABSTRACT:

The purpose of this paper is to present on-going research in non-destructive testing (NDT) of carbon-fiber

reinforced polymer (CFRP) laminate plate bond in FRP structural systems applied to reinforced concrete (RC)

highway bridges. Using the NDT impact-echo principle a light mobile impact machine made with a 3D-printed

polylactide plastic frame produces multiple acoustic (low frequency) signals per meter of CFRP plate bonded to

RC-bridge structural members. Each impact produces a specific signal waveform signature defined by the CFRP-

plate concrete bond condition. A change in plate bond to a de-bonded condition produces a uniquely different

waveform signature. The impact waveforms are characterized by exponentially decaying sinusoids with differing

decay rates, times, frequencies, and amplitudes. These waveform differences markedly identify changes in CFRP-

plate bond condition. Signal analysis of recorded impact waveform signals provides a visual profile and a digital

data base record of bond conditions across the length of the CFRP plate. The objective of the NDT impact

procedure presented in this paper is to evaluate (test) long lengths CFRP plates bonded to highway bridges. This

objective is driven, in part, by a requirement to evaluate a number of CFRP-strengthened bridges in the Republic

of Macedonia to determine plate bond condition 17 years after installation. The paper presents results of recent

field testing with the impact procedure on existing FRP-strengthened highway bridges in the State of Missouri

using a mobile impact machine. Test results are compiled to show bond conditions over the length of the FRP

applications. Successful development and application of this NDT impact procedure will provide bridge engineers

an effective field protocol (tool) for long-term testing of CFRP-structural systems applied to multiple highway

bridges in a national highway system. With periodic testing the impact waveform data base will establish a record

for FRP-system bond behaviour over time on RC highway bridges.



306


DISTRIBUTED OPTICAL FIBRE SENSORS TO MONITOR PRESTRESSED

CONCRETE BRIDGE BEAM STRENGTHENED WITH BONDED FRP

Aghiad Khadour1, Marc Quiertant1, Gonzague Six1, Corentin Le Roy2, Christophe Aubagnac2 1Ifsttar, Champs-sur-Marne, France ; 2Cerema, Centre Est, Autun, France


KEYWORDS :

Distributed optical fibre sensors; Experimental study; Bond and interfacial stresses; Strengthening with bonded

FRP

ABSTRACT:

The mechanical behaviour of large scale pre-stressed concrete beam strengthened with adhesively bonded FRP

was studied; using distributed optical fibre sensing technique. The sensing fibres were installed into concrete

structure and between FRP layers.

The high spatial resolution strain measurements leads to measure precisely the strain profile along the strengthened

beam and to identify the pre-existing cracks and the new cracks which appeared during the 3 points bending test

carried-out in 2014, and during shear test performed to the half of the beam in 2016. The role of FRP layers for

strengthening and for the control of the crack openings was possible using the different fibres between the FRP

layers.

Figure 1 : Strain profile obtained during shear loading steps (spatial resolution: 1 cm; measurement incertitude:

4 microstrain)

0 1 2 3 4 5 6 7 8

0

50

100

150

200

250

300

Str

ain

(m

icro

stra

in)

L (m)

01-200kN

02-300kN

03-400kN

04-500kN

05-600kN

06-700kN

07-800kN

08-900kN

09-1000kN



307


SMART MONITORING OF THE FRP COMPOSITE BRIDGE WITH DISTRIBUTED

FIBRE OPTIC SENSORS

T. Siwowski1, M. Rajchel1, R. Sienko2 and L. Bednarski3

1 Rzeszow University of Technology, Poland, Email:[email protected]

2 Cracow University of Technology, Poland, Email: [email protected]

3 AGH University of Science and Technology, Poland, Email: [email protected]

KEYWORDS Distributed fibre optic sensors, Rayleigh scattering, all-composite FRP bridge, monitoring.

ABSTRACT Considering the worldwide recognized advantages of fibre optic sensors as measuring devices in the SHM of the

FRP bridges and the unique ability to measure the long range distributed strain and temperature along the entire

bridge superstructure, the distributed fibre optic sensors (DFOS) technology was chosen for the SHM system of

the first Polish all-composite FRP bridge. The initial results of the SHM with the DFOS technology are the main

subject of the paper. Analysis of the results obtained in the field proved the effectiveness of the distributed fibre

optic sensors based on Rayleigh scattering for the SHM purposes. Wide range of practical problems related to

sensor installation, fibre connection, and data processing were successfully solved in the pilot field application

described in this paper. The smart DFOS sensors can ensure an acceptable measurement accuracy, thereby

providing reliable strains referring to time-dependent behaviour of the FRP bridge span to assess the safety and

serviceability of the all-composite bridge.



308


CONSTRUCTION OF NIPIGON RIVER CABLE-STAYED BRIDGE USING

PRECAST CONCRETE PANELS REINFORCED WITH GLASS FRP REBARS

Hamdy M. Mohamed1 and Brahim Benmokrane2


[email protected]


[email protected]

KEYWORD

Fields applications and case studies; Structure; FRP internal reinforcement.

ABSTRACT

The Nipigon River cable-stayed bridge in Northwest Ontario (Canada) is the first of its kind in the Ontario highway

system and the world’s first cable-stayed bridge with glass-fiber-reinforced-polymer (GFRP) reinforced-concrete

(RC) deck slabs. The four-lane bridge is located on Trans-Canada highway crossing over the Nipigon River as

part of the extension of the Highway 11/17 corridor east of Thunder Bay, Northwestern Ontario, Canada. The

precast GFRP-RC bridge-deck panels were designed taking into account flexural and compressive straining

actions. Four hundred and eighty GFRP-RC precast panels measuring 3.6 m x 7.0 m were fabricated for the bridge

deck. Design of the GFRP reinforced concrete bridge deck slab will be presented and discussed in this manuscript.

The objectives of this study are to implement FRP bars in RC cable stayed bridge to overcome the steel expansive-

corrosion issues and related deterioration problems; to assess the in-service performance of the FRP-RC bridge

deck slab after several years of operation; and to design durable and maintenance-free concrete for cable stayed

bridge. Design and reinforcement details of deck slab are used to illustrate code requirements, deck-slab analysis,

and design procedures.



Composites in Civil Engineering (CICE 2018), PARIS 17-19 JULY 2018


A CONSISTENT DESIGN CONCEPT FOR BOLTED CONNECTIONS

AND APPLICATION TO INDUSTRIAL STRUCTURES

Matthias Oppe1, J Toby Mottram 2, Jan Knippers 1,3

1 Knippers Helbig GmbH, Stuttgart (Germany); 2 Warwick University, School of Engineering, Coventry

(England); 3 Stuttgart University - Institute of Building Structures and Structural Design, Stuttgart (Germany)

ABSTRACT

Presented in this paper is an introduction to the development of structural design clauses for bolted

connections (and joints) towards the preparation of a future Eurocode for fibre reinforced polymer

materials. The impetus and drive, from within the composite community, for this code writing has been,

for example, the increasing annual number of applications of pultruded shapes and mould components

of glass fibre reinforced polymer (FRP) in bridge and industrial structures. Since detachable structural

joints with mechanical fasteners remain the most reliable and controllable method for connecting

structural members in FRP structures there is a need for a consistent design concept for bolted

connections, which is presented in Ascione et al. (2016). The first part of this paper gives historical

context to, and introduces the content of Chapter 8 for Connections in this Joint Research Centre Science

and Policy report. In the second part of the paper we present an application of mechanically fastened

bolted connections for cooling tower structures at an electricity-generating power plant in Egypt.

KEYWORDS

All FRP structures, material, codes, standards and design guidelines, case studies.




REACTIVE ORGANOCLAY AND OTHER NANOFILLERS AS A MEAN TO

IMPROVE POLYMER ADHESIVE OR MATRIX FORMULATIONS

Mohamed M. Chehimi1, Beata Strzemiecka2, Karim Benzarti3 1 ICMPE, CNRS, 94320 Thiais, France

2 Poznan University of Technology, 60-965 Poznan, Poland 3 Laboratoire Navier, Champs sur Marne, F-77447 Marne la Vallée, Cedex 2, France.

KEYWORDS :

Reactive nanofillers; Organoclay ; Polymer composites

ABSTRACT:

Mechanical properties of polymer composites depend to a very large extent on the filler-polymer matrix

interactions. Indeed, mechanical stress applied to the composite is transferred to the interface/interphase region

which will either resist or fail depending primarily on the molecular interactions between the filler and the polymer.

In this context, we have spent time and effort designing reactive clay and silica-based fillers using ammonium

salts, silanes or diazonium compounds. These coupling agents permit to initiate polymerization to obtain

inorganic/polymer nanocomposites fillers, or to design organo-fillers that bear surface bound reactive groups

towards polymeric matrices, e.g. epoxy and phenolic resins.

Figure 1 displays examples of reactive fillers we have designed. The Clay/PGMA nanocomposite fillers present

the advantages to be highly exfoliated on the one hand, and reactive towards aminated hardener of epoxy resins,

on the other hand. The final epoxy composites are transparent and robust. As far as silica grafted with para-

hydroxybenzyl groups readily react with phenolic resins. This is an important finding as such fillers avoid the use

of toxic crosslinkers such as hexamethylenetetramine.

High performances analytical tools were employed to track modifications of fillers, namely XPS, FTIR,

thermogravimetric analysis and TEM.

Mechanical properties were determined for composites in terms of e.g. flexural strength, fracture toughness,

storage and loss moduli. Epoxy composite curing could also be monitored by measuring viscosity of the composite

formulation.

In summary, surface modification of nanofillers is of paramount importance to improve the mechanical properties

of polymer composites materials. Definitely diazonium salts should be included in the composite chemist tool box

as they provide efficient modification of the nanofillers and provide chemical reactivity towards the polymer

matrices under test. Such chemical reactivity of the nanofiller accounts for remarkable improvements of the

mechanical properties upon filler surface modification.

Figure 1. Examples of clay and silica nanofillers: (a) pristine clay; (b) ammonium-exchanged clay;

(c) diazonium-modified clay; (d) clay-polymer composite nanofiller via silane or onium chemistries;

(e) diazonium-modified silica nanoparticles.

R

R

(a) (b) (c) (d) (e)

R

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