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DALILA BINTI KAMARUZAMAN

29 AUGUST 1983

THE BEHAVIOUR OF GLULAM BEAM

STRENGTHENED USING FIBRE REINFORCED

POLYMER

2007/2008

830829-03-5866 ASSOC. PROF. DR ABD. LATIF SALEH

PSZ 19:16 (Pind. 1/07)

“I/We* hereby declare that I/we* have read this thesis and in my/our*

opinion this thesis is sufficient in terms of scope and quality for the

award of the degree of Master of Engineering (Civil - Structure)

Signature : ....................................................

Name of Supervisor I : Assoc. Prof. Dr. Abd. Latif Saleh

Date : ....................................................

Signature : ....................................................

Name of Supervisor II : Dr. Suhaimi Abu Bakar

Date : ....................................................

* Delete as necessary

THE BEHAVIOUR OF GLULAM BEAM STRENGTHENED USING FIBRE

REINFORCED POLYMER

DALILA BINTI KAMARUZAMAN

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Civil – Structure)

FACULTY OF CIVIL ENGINEERING

UNIVERSITI TEKNOLOGI MALAYSIA

NOVEMBER 2007

ii

I declare that this thesis entitled “The Behaviour of Glulam Beam Strengthened Using

Fibre Reinforced Polymer’ is the result of my own research except as cited in the

references. The thesis has not been accepted for any degree and is not concurrently

submitted in candidature of any other degree.

Signature : ………………………..

Name : DALILA BINTI KAMARUZAMAN

Date : ………………………..

iii

Dedicated to my beloved family,

Abah, Umi, Abe, Ina, Apih, Kimah, Bibah and Fatin

iv

ACKNOWLEDGEMENT

The utmost and heartiest gratitude is due to my supervisor, Associate Professor

Dr. Abd. Latif Saleh, who always shares his invaluable knowledge and provides

constructive advice, and enthusiastic support to my research. I am also grateful to him

for sharing his precious time to view the thesis. Certainly, this thesis will not come true

without his guidance.

I also wish to thank my co-supervisor, Dr. Suhaimi Abu Bakar for his useful

advice and helpful guidance also sharing his knowledge and technical advice throughout

the project.

Thanks to all technicians in Structure and Material Laboratory especially to En.

Zailani Aman, En. Razale Mohamad, En. Raja Ezar Ishamuddin and En. Jaafar Ahmad

for their guide and help during the laboratory work.

A special thanks to my friends and classmate, Wan Rizana, Nur Fatimah and Siti

Radiah for their hand and support in order to complete the project.

Finally, I wish to thank Universiti Teknologi Malaysia for providing the

materials and equipments to accomplish the project.

v

ABSTRACT

Fibre Reinforced Polymer (FRP) materials are becoming popular in the Civil

Engineering community due to their favourable characteristics such as high strength-to

weight ratio, electromagnetic neutrality, and good corrosion resistance. FRP rods and

plate are being used as reinforcement of newly-constructed concrete members in

aggressive environments or as surface reinforcement for strengthening purposes of

existing concrete. However, the use of FRP in timber structure is quite new in Malaysia

and this study investigates the possibility of using Glass FRP (GFRP) rods as glued-in

reinforcement of glulam beams. This study presents the behaviour of glulam beam

reinforced with GFRP rods at different position. Specimens of glulam beam are tested

with and without GFRP rods as reinforcement. Flexural behaviour of GFRP reinforced

glulam beams are compared with unreinforced glulam beams and solid beams that are

used as control specimen. The experimental results shows that by using the GFRP rods

as glued-in reinforcement for the glulam beam have some influence in increasing the

ultimate capacity and stiffness of the beam, and also shows some decreases in deflection.

vi

ABSTRAK

Polimer bertetulang gentian (FRP) adalah semakin popular penggunaannya

dalam bidang Kejuruteraan Awam disebabkan sifatnya yang mempunyai nisbah

kekuatan-berat yang tinggi, kestabilan elektromagnet dan ketahanan terhadap kakisan.

Rod FRP dan plat biasa digunakan sebagai tetulang di dalam pembinaan bangunan

konkrit baru yang terdedah kepada persekitaran yang agresif atau sebagai pengukuh

pada permukaan konkrit bagi bangunan yang sedia ada. Walau bagaimanapun,

penggunaan FRP dalam struktur kayu masih lagi baru di Malaysia dan kajian ini

dijalankan untuk melihat kebolehgunaan polimer bertetulang gentian kaca (GFRP)

sebagai tetulang di dalam rasuk kayu berperekat. Kajian ini mengemukakan kelakuan

rasuk kayu berperekat yang menggunakan rod GFRP sebagai tetulang dan di letakkan

pada kedudukan yang berbeza. Spesimen rasuk kayu berperekat diuji dengan kehadiran

dan tanpa kehadiran GFRP sebagai tetulang. Kelakunan lenturan rasuk kayu berperekat

bertetulang dibandingkan dengan rasuk kayu berperekat tanpa tetulang dan rasuk kayu

padu sebagai spesimen kawalan. Keputusan ujikaji menunjukkan bahawa penggunaan

GFRP sebagai tetulang telah memberikan kesan dalam meningkatkan keupayaan beban

muktamad dan kekakuan rasuk, dan juga menunjukkan pengurangan dalam pesongan

rasuk.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xv

LIST OF APPENDICES xvii

I INTRODUCTION

1.1 Foreword 1

1.2 Problem Statement 2

1.3 Aim and Objectives 4

1.4 Scope of Study 5

1.5 Significant of Study 5

viii

II LITERATURE REVIEW

2.1 General 6

2.2 Wood Parameters 7

2.2.1 Moisture Content (%) 7

2.2.2 Specific Gravity 8

2.2.3 Density 8

2.3 Mechanical Properties of Wood 9

2.3.1 Orthotropic Nature of Wood 9

2.3.2 Elastic Properties 10

2.3.2.1 Modulus of Elasticity, E 10

2.3.2.2 Modulus of Rigidity, G 11

2.3.2.3 Modulus of Rupture, MOR 11

2.3.2.4 Poisson’s Ratio 12

2.3.2.5 Stress – Strain diagram of Wood 13

2.3.3 Strength Properties 14

2.3.3.1 Compressive Strength 14

Parallel to Grain

2.3.3.2 Compressive Stress 15

Perpendicular to Grain

2.3.3.3 Shear Strength Parallel to Grain 15

2.3.3.4 Impact Bending 15

2.3.3.5 Tensile Strength Parallel 16

to Grain

2.4 Hardwood 16

2.4.1 Mechanical Properties of Hardwood 19

from MS 544: Part 3: 2001

2.5 Glued-Laminated Timber (Glulam) 20

2.5.1 Mechanical Properties of Glulam 21

2.5.1.1 Modulus of Elasticity (MOE) 21

2.5.1.2 Strength 22

2.5.2 Fabrication of Glulam Timber Beam. 23

ix

2.5.3 Adhesive 24

2.5.4 Glue Joints 25

2.5.5 Cramping Time and Cramping 26

Pressure

2.6 Fibre Reinforced Polymer (FRP) 27

2.6.1 Mechanical properties of FRP 28

2.6.2 Possible applications of FRP 29

in timber structures

2.7 Analysis of Glued Laminated Beam 30

2.8 Failure modes of reinforced glulam beams 31

2.9 Previous Researches 32

III METHODOLOGY AND EXPERIMENTAL PROGRAMME

3.1 Introduction 36

3.2 Experimental Procedure 39

3.3 Preparation of Material 40

3.3.1 Compression Specimens 40

3.3.2 Beam Specimen 41

3.3.3 Fabrication of Glulam Beam 43

Specimen

3.3.4 Gluing Glass Fibre Reinforce 45

Polymer (GFRP) Rods to Beam Specimen

3.3.5 Clamping Process 48

3.3.6 Final Sizing of Beams 49

3.4 Calibration of Strain Gauges, Displacement 50

Transducers and Load Cell

3.5 Compression Tests 52

3.5.1 Instrumentation and Test Set-Up 52

3.5.2 Compression Test Procedure 53

x

3.6 Beam Tests 54

3.6.1 Instrumentation and Test Set-Up 54

3.6.2 Test Procedure of Beam 55

3.7 Moisture Content Tests 57

CHAPTER IV TEST RESULTS AND DISCUSSION

4.1 Introduction 58

4.2 Compression Test Result 58

4.3 Beam Test Results 61

4.3.1 Load – Deflection Curve 61

4.3.2 Types of Failure 66

4.3.3 Strain Profile 69

4.3.4 Modulus of Elasticity (E) 76

4.3.5 Moisture Content Test Results 77

CHAPTER V CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 79

5.2 Recommendations 81

REFERENCES 82

APPENDIX A 85

APPENDIX B 95

APPENDIX C 98

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Classification of Hardwood according to durability 17

at 15% moisture content

2.2 Grade stresses and modulus of elasticity for various 19

strength classes

2.3 Advantages and disadvantages of using glulam timber 21

2.4 Group of adhesive and its usage 25

2.5 Mechanical Properties of FRP 28

3.1 Properties of GFRP rod as certified by the 42

manufacturer

3.2 Properties of Sikadur-30 as certified by the 46

manufacturer

4.1 Compression parallel to grain results for Kekatong 60

species

4.2 Maximum Load and deflection value for each specimen 61

4.3 Type of failure for each beam specimen 66

4.4 The Modulus of elasticity for all beam specimen 77

4.5 The percentage of moisture content for each sample 78

from beam specimens

xii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Three principal axes of wood with respect to grain 10

direction and growth rings

2.2 Normal distribution of the modulus of elasticity 11

2.3 Typical representation of the stress – strain diagram 13

of a wood composite

2.4 Types of glue joint 26

2.5 Possibilities of using FRP in timber engineering 29

2.6 Failure modes of glulam timber strengthen using FRP 31

3.1 Research methodology 38

3.2 Flow Chart of Experimental Study 39

3.3 Dimensions of Kekatong timber specimen for 40

compression test

3.4 Kekatong samples for compression test 41

3.5 (a) Kekatong , (b) GFRP rods 42

3.6 The dimension of the beam specimen. 43

3.7 Cross section of the test specimens 43

3.8 Phenol Resorcinol Formaldehyde adhesive 44

and its hardener

xiii

3.9 Process of spreading glue using roller glue spreader 45

3.10 Sikadur-30 47

3.11 Process of attaching FRP rods to the beam specimen 47

3.12 Eurotrade clamping machine 48

3.13 Beam specimen ready to be clamped 49

3.14 Beam specimen ready for testing 50

3.15 NMB data logger 51

3.16 Calibration frame and digital vernier calliper for 52

calibration process

3.17 Dartec universal testing machine 53

3.18 Location of omega strain gauge 55

3.19 Loading diagram for glulam beam tests 56

3.20 Bending test set-up for the beam specimen in laboratory 56

4.1 Compression parallel to grain curve for sample 1 Kekatong 59



4.4 Load-Deflection Curve for Type 1 62

4.5 Load-Deflection Curve for Type 2 62

4.6 Load-Deflection curve for Type 3 63



4.9 Load-Deflection curve for all types of beam 64

4.10 Failure at tension region for beam Type 1 (a) S1 (b) S2 67

4.11 Failure at tension region for beam Type 2 (a) S1 (b) S2 67

xiv

4.12 Failure due to delamination for beam Type 3 (a) S1 (b) S2 68

4.13 Failure due to delamination for beam Type 4 (a) S1 (b) S2 68

4.14 Failure mode for beam Type 5 at tension region (a) S1 69

due to delamination (b) S2

4.15 Strain Profile for Type 1 [S1] 70










xv

LIST OF SYMBOLS

A = cross-sectional area.

ASTM = American Standard for Testing of Material.

a = length from support to point load.

BMD = bending moment diagram.

BS = British Standard.

b = width.

E = modulus of elasticity.

h = height of sample.

I = Second moment of inertia.

L = length of span.

M = moment.

m.c. = moisture content.

MOE = modulus of elasticity.

MOR = modulus of rupture.

MS = Malaysia Standard.

P = maximum load.

PL = proportional load limit.

PRF = Phenol Resorcinol Formaldehyde.

xvi

SFD = shear force diagram.

SG = strength group.

WBF = weather and boil proof.

= deflection.

s = modulus of rupture.

s c = compressive strength.

s t = tensile strength.

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Bending Test Result for All Beam Type 90

B Calibration of Omega Strain Gauge 100

C Strain Value for All Beam Type 103

CHAPTER I

INTRODUCTION

1.1 Foreword

Timber is one of the oldest building materials ever used by mankind. Timber

is a discontinuous, heterogeneous, orthotropic, inelastic, and hygroscopic material

[1]. From earliest recorded times timber has been a ubiquitous material that had been

used by ancient Egyptian as early as 2500 BC. History shows that the unique

characteristics and the proportionally large quantity of wood have made it a natural

material for houses, bridges, vehicles, furniture, tools and decorative objects. It has

been used for its cheap price, high strength to weight ratio, decoration and

availability.

Wood technology in foreign countries such as western country and Japan are

more advanced. They utilize wood not only for structural material, but also as an

aesthetical material. The most utilize structural technology for wood is glued-

laminated structural member or known as “glulam” [2].

2

Glulam, are a highly engineered wood product. Essentially, they are made up

of material glued together from smaller pieces of wood, either straight or curved

form, with the grain of all laminations parallel to the length of the member. Glulam

members are different from plywood in which the grain direction of adjacent plies of

veneer is at right angles to each other. In Malaysia, glulam has been identified as one

of the potential means to promote structural timber construction in the country.

Among the advantages of glulam are its efficiency and effectiveness in material

utilization, excellent fire performance, aesthetic appeal and versatility [3]. This study

will focus on the behaviour of glulam beam strengthened using fibre reinforced

polymer (FRP).

1.2 Problem Statement

A glulam structural member is made with layer of smaller piece of wood with

the use of strong adhesive for lamination [2]. Lamination of glulam structural

member may be of any thickness or length made up of different types of wood or

formed curved or camber. Glulam is different from plywood as the grain of all

lamination is essentially parallel to the length of glulam member.

When deciding to use a structural glulam member such as a glulam beam,

designers will design the glulam using the data of prefabricated glulam beam from

the manufacturers or standards code of practice available such as BS5268 or MS544.

When designing using data of prefabricated glulam beam, designers will be confined

to designing the glulam timber beam using specification and calculation provided by

the manufacturer. Wood species that used for the glulam are totally dependent by the

manufacture.

3

Using standard code of practice, the determination of the number of wood

species used is one grade species for the whole section; therefore it does not consider

a glulam beam made up of different wood species. When using a standard code of

practice such as BS5268, designers is required to determine permissible bending

stress, bearing stress, deflection and shear stress. All calculation is based on the

stress grade of the one wood species that is used. However, not all laminations of a

stress grade wood have the same modulus of elasticity and it was a difficult to predict

the effect.

The problem here is that it is hard to find a solid timber which is bigger than

the one that available in commercial sizes. In order to get the desired size, it has to be

specially ordered from the manufacturer and this can increase the cost. In order to

deal with the problem, glulam had been introduced as solution to the problem. Other

problem that needs to be considered is the strength of the glulam beam laminated

with hardwood at the outer layer and softwood at inner layer.

Glulam beams loaded by bending moments fail at the tension side at the

position of knots or finger joints. Due to this failure mode glulam beams are mainly

reinforced at the tension side to strengthen the weak cross-sections. The

reinforcement for glulam beams should have a high modulus of elasticity (MOE) and

a large tensile strain at failure. Materials considered in the past were steel, glass fibre

reinforced polymer (GFRP) and since a few years carbon fibre reinforced polymer

(CFRP) and aramid fibre reinforced polymer (AFRP). Fibre reinforced polymer

(FRP) has the advantage of a high MOE and a high tensile strength although it is

generally lower than steel. The disadvantage of steel is the low yield strength leading

to plastic deformations before the timber fails. FRP reinforcements do not show this

behaviour. An effective reinforcement leads to a plastic behaviour on the timber

compression side. In unreinforced glulam beams this effect hardly occurs and design

models therefore do not take into account this effect. Therefore, for FRP reinforced

beams different design models are necessary.

4

When considering all the factors above, the study is conducted to determine

the behaviour of glulam beam strengthened using fibre reinforced polymer. The

study will also determine the permissible stress and strain of glulam beam and the

flexural strength of the glulam beam.

1.3 Aim and Objectives

The aim of this study is to determine the behaviour of the glulam beam

strengthened using Fibre Reinforced Polymer (FRP).

The objective of the study is as follow:

(i) Determine the capacity of loading for glulam strengthened using fibre

reinforced polymer

(ii) Determine the position of reinforcement that will give the highest

strength

(iii) To compare the bending strength of solid timber, unreinforced glulam

and reinforced glulam beam.

5

1.4 Scope of Study

The scope of study will implement the following confinement and

specification:

(i) Study of the structural glulam is confined to straight beam only

(ii) Using tropical Malaysian wood species of Kekatong for analysis

(iii) Using glulam laminated with hardwood and glulam laminated with

different species of tropical wood

(iv) FRP rod will be used as reinforcement

1.5 Significant of Study

Using different wood species that is from different strength group of timber

to make a glulam will give a significant economic value where some cost can be

saved. When it is hard to obtain large solid timber in the market, the use of smaller

sections or portions of different wood to form a glulam is an option that can be

considered. The depletion of natural wood sources can be cut down if designer can

make use of every wood resource. With this way, utilizing every inch of wood

resources is necessary in order to reduce wastage. This study is to expose local

hardwood and glulam technology to local wood user as a valid and renewable

structural material for construction. This study is also to explore any other material

that can be used as reinforcement for timber structural member.

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