advanced structural materials for concrete...

Advanced Structural Materials for Concrete Bridges

Tuesday, December 3, 20191:00-2:30 PM ET

TRANSPORTATION RESEARCH BOARD

The Transportation Research Board has met the standards and

requirements of the Registered Continuing Education Providers Program.

Credit earned on completion of this program will be reported to RCEP. A

certificate of completion will be issued to participants that have registered

and attended the entire session. As such, it does not include content that

may be deemed or construed to be an approval or endorsement by RCEP.

Purpose

To identify and compare several advanced performance structural materials that may be used on bridges.

Learning Objectives

At the end of this webinar, you will be able to:

• List four new advanced structural materials for concrete bridge applications

• Describe the benefits of each advanced structural material

• Describe the challenges of implementing these structural materials

PDH Certificate Information• This webinar is valued at 1.5 Professional Development

Hours (PDH)• Instructions on retrieving your certificate will be found in

your webinar reminder and follow-up emails• You must register and attend as an individual to receive a

PDH certificate• Certificates of Completion will be issued only to individuals

who register for and attend the entire webinar session –this includes Q&A

• TRB will report your hours within one week• Questions? Contact Reggie Gillum at RGillum@nas.edu

Michigan Department of TransportationFRP prestressing codes and guidance

Matthew J. Chynoweth, P.E.Chief Bridge EngineerDirector, Bureau of Bridges and Structures

Introduction of current needs in bridge durability & Advanced Structural Materials of interest

• Material Systems:• Prestressed Concrete using either CFRP & HSSS • Reinforced Concrete using FRP rebar (Glass & Basalt FRP)• Ultra-High Performance Concrete (UHPC)

• without reinforcing;• with traditional reinforcing and/or prestressing (carbon-steel)• with ASM reinforcing and/or prestressing (HSSS or FRP)

• Justification of higher initial cost from ASM’s• Durability Enhancement – potentially increased Service Life / significantly reduced Thru-life

Maintenance Repair & Rehabilitation (MRR);• Resilience – superior Mechanical Performance, Damage Tolerance for continued service,

increased Adaptability options (long-term widening, structure repurposing);• Sustainability – Reduced embodied energy, CO2 emissions using circular economy principals;• Life-Cycle Cost Analysis (LCC) - economic comparisons;• Life Cycle Analysis (LCA) - environmental comparisons

A recent TRB webinar covered the National AASHTO LRFD Guide Specifications:

TRB Webinar: Carbon Fiber-Reinforced Polymer Systems for Concrete Structures

http://www.trb.org/BridgesOtherStructures/Blurbs/179731.aspx

COLLEGE OF ENGINEERING

Stages of prestressing force

𝑃𝑃𝑗𝑗: Initial jacking force

𝑃𝑃𝑝𝑝𝑝𝑝𝑝𝑝: Prestressing force immediately before transfer

𝑃𝑃𝑝𝑝𝑝𝑝𝑝𝑝 = 𝑃𝑃𝑗𝑗

𝑃𝑃𝑖𝑖: Prestressing force immediately after transfer

𝑃𝑃𝑖𝑖 = 𝑃𝑃𝑝𝑝𝑝𝑝𝑝𝑝 𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝐸𝐸𝑠𝑠𝑠𝑠𝐸𝐸𝑠𝑠𝑠𝑠 𝐸𝐸𝑠𝑠𝐸𝐸𝐸𝐸𝑠𝑠𝐸𝐸, 𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝

𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝(𝑘𝑘𝐸𝐸𝐸𝐸) = 10.0𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝𝐴𝐴𝑝𝑝𝑝𝑝𝐴𝐴𝑔𝑔

𝛾𝛾ℎ𝛾𝛾𝑠𝑠𝑝𝑝 + 12.0𝛾𝛾ℎ𝛾𝛾𝑠𝑠𝑝𝑝 + 𝑓𝑓𝑝𝑝𝑝𝑝

𝛾𝛾ℎ = 1.7 0.01H

𝛾𝛾𝑠𝑠𝑝𝑝 =5

(1 + 𝑓𝑓𝑐𝑐𝑖𝑖′ )

𝑃𝑃𝑒𝑒: Effective prestressing force after long-term losses

𝑃𝑃𝑒𝑒 = 𝑃𝑃𝑖𝑖 { 𝐶𝐶𝑠𝑠𝑠𝑠𝑠𝑠𝐶𝐶 + 𝐸𝐸𝑠𝑠𝑠𝐸𝐸𝑠𝑠𝑘𝑘𝐸𝐸𝑠𝑠𝑠𝑠 + 𝑠𝑠𝑠𝑠𝐸𝐸𝐸𝐸𝑟𝑟𝐸𝐸𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠 𝐸𝐸𝑠𝑠𝐸𝐸𝐸𝐸, 𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝} 𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝

H: Humidity = 70

𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝: stress in FRP immediately prior to transfer

𝑓𝑓𝑝𝑝𝑝𝑝

𝑓𝑓𝑝𝑝𝑝𝑝𝑝𝑝

Check stresses @ service limit state

Prestressing force (𝑃𝑃𝑒𝑒)

Self-weight of the beam (or non-composite section) + Dead load + superimposed dead loads + Live loads

Concrete full strength (𝑓𝑓𝑐𝑐′)

𝜎𝜎𝑝𝑝𝑏𝑏𝑝𝑝 = −𝑃𝑃𝑒𝑒𝐴𝐴𝑛𝑛𝑛𝑛

𝑃𝑃𝑒𝑒.𝑒𝑒𝐼𝐼𝑛𝑛𝑛𝑛

𝑦𝑦𝑝𝑝 + 𝑀𝑀𝑛𝑛𝑛𝑛𝐼𝐼𝑛𝑛𝑛𝑛

𝑦𝑦𝑝𝑝 + 𝑀𝑀𝐷𝐷𝑛𝑛𝐼𝐼𝑛𝑛𝑦𝑦𝑝𝑝 + 0.8 𝑀𝑀𝐿𝐿𝐿𝐿

𝐼𝐼𝑛𝑛𝑦𝑦𝑝𝑝 (Service III)

𝜎𝜎𝑝𝑝𝑏𝑏𝑝𝑝 = −𝑃𝑃𝑒𝑒𝐴𝐴𝑛𝑛𝑛𝑛

+ 𝑃𝑃𝑒𝑒.𝑒𝑒𝐼𝐼𝑛𝑛𝑛𝑛

𝑦𝑦𝑝𝑝𝑀𝑀𝑛𝑛𝑛𝑛𝐼𝐼𝑛𝑛𝑛𝑛

𝑦𝑦𝑝𝑝𝑀𝑀𝐷𝐷𝑛𝑛𝐼𝐼𝑛𝑛𝑦𝑦𝑝𝑝

𝑀𝑀𝐿𝐿𝐿𝐿𝐼𝐼𝑛𝑛𝑦𝑦𝑝𝑝 (Service I) 𝑠𝑠𝐸𝐸

𝐸𝐸

Critical section@ mid-span

MDOT guide:

No tension is allowed in pre-compressed

tensile zone of CFRP prestressed beams

Most common Less common

𝜌𝜌𝑝𝑝𝑒𝑒 =𝐴𝐴𝑝𝑝𝑒𝑒𝑏𝑏.𝑑𝑑1

Reinforcementratio Depth of stress block Section design Failure mode

𝜌𝜌𝑝𝑝𝑒𝑒 < 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝛽𝛽1 𝐸𝐸 < 𝑑𝑑 Rectangular Tension𝜌𝜌𝑝𝑝𝑒𝑒 > 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝛽𝛽1 𝐸𝐸 < 𝑑𝑑 Rectangular Compression𝜌𝜌𝑝𝑝𝑒𝑒 < 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝑑𝑑 < 𝛽𝛽1 𝐸𝐸 < 𝑑𝑑 + 𝑝𝑝 Flanged Tension𝜌𝜌𝑝𝑝𝑒𝑒 > 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝑑𝑑 < 𝛽𝛽1 𝐸𝐸 < 𝑑𝑑 + 𝑝𝑝 Flanged Compression

𝜌𝜌𝑝𝑝𝑒𝑒 < 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝛽𝛽1 𝐸𝐸 > 𝑑𝑑 + 𝑝𝑝Double Flanged Tension

𝜌𝜌𝑝𝑝𝑒𝑒 > 𝜌𝜌𝑝𝑝_𝑝𝑝𝑏𝑏𝑏𝑏 𝛽𝛽1 𝐸𝐸 > 𝑑𝑑 + 𝑝𝑝Double Flanged Compression

𝑑𝑑: Depth of deck slab 𝑝𝑝: Depth of top flange of beam

𝜀𝜀1𝜀𝜀2

𝜀𝜀3𝜀𝜀4

𝜀𝜀𝑖𝑖

𝜀𝜀𝑐𝑐

𝜀𝜀𝑖𝑖 = 𝜀𝜀1𝑑𝑑𝑖𝑖 𝐸𝐸𝑑𝑑1 𝐸𝐸

𝜀𝜀𝑖𝑖 = Strain in CFRP reinforcement at layer 𝐸𝐸, not including the effective prestressing strain 𝜀𝜀𝑝𝑝𝑒𝑒

Strain Distribution

𝑇𝑇1𝑇𝑇2

𝑇𝑇3𝑇𝑇4

𝑃𝑃𝑝𝑝𝑝𝑝𝑒𝑒𝑠𝑠𝑝𝑝𝑝𝑝𝑒𝑒𝑠𝑠𝑠𝑠

𝜀𝜀𝑐𝑐

𝑇𝑇𝑖𝑖 = 𝜀𝜀𝑖𝑖 .𝑠𝑠𝑖𝑖 .𝐸𝐸𝑝𝑝.𝐸𝐸𝑝𝑝

𝑇𝑇𝑖𝑖 = Force in CFRP reinforcement at layer 𝐸𝐸, not including the effective prestressing force 𝑃𝑃𝑒𝑒

Forces in section

𝑇𝑇𝑖𝑖

𝐹𝐹𝑐𝑐

𝐴𝐴𝑝𝑝𝑒𝑒 = �𝑖𝑖=1

𝑖𝑖=𝑚𝑚

𝐴𝐴𝑖𝑖_𝑒𝑒𝑒𝑒𝑒𝑒 𝜌𝜌𝑝𝑝𝑒𝑒 =𝐴𝐴𝑝𝑝𝑒𝑒𝑏𝑏.𝑑𝑑1

Calculate the neutral axis depth for a balanced section, 𝐸𝐸𝑝𝑝𝑏𝑏𝑏𝑏𝐸𝐸𝑝𝑝𝑏𝑏𝑏𝑏𝑑𝑑1

=𝜀𝜀𝑐𝑐𝑐𝑐

𝜀𝜀𝑐𝑐𝑐𝑐 + (𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒)

(rectangular sections)

𝜌𝜌𝑝𝑝𝑒𝑒 < 𝜌𝜌𝑝𝑝𝑏𝑏𝑏𝑏𝜌𝜌𝑝𝑝𝑒𝑒 > 𝜌𝜌𝑝𝑝𝑏𝑏𝑏𝑏

Tension failure

Compression failure

𝜌𝜌𝑝𝑝𝑏𝑏𝑏𝑏 =0.85𝑓𝑓𝑐𝑐′𝛽𝛽1𝐸𝐸𝑝𝑝𝑏𝑏𝑏𝑏𝑏𝑏𝑤𝑤 + 0.85𝑓𝑓𝑐𝑐′ 𝑝𝑝 𝑏𝑏 𝑏𝑏𝑤𝑤 𝑃𝑃𝑒𝑒

𝐸𝐸𝑝𝑝 𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒 𝑏𝑏𝑑𝑑1(Flanged sections)

𝜌𝜌𝑝𝑝𝑏𝑏𝑏𝑏 =0.85𝑓𝑓𝑐𝑐′𝛽𝛽1𝐸𝐸𝑝𝑝𝑏𝑏𝑏𝑏𝑏𝑏 𝑃𝑃𝑒𝑒𝐸𝐸𝑝𝑝 𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒 𝑏𝑏𝑑𝑑1

Calculate the depth of the N.A., 𝐸𝐸

Calculate the flexural strain in different reinforcement layers & strain in concrete

𝜀𝜀𝑖𝑖 = 𝜀𝜀1𝑑𝑑𝑖𝑖 𝐸𝐸𝑑𝑑1 𝐸𝐸

𝜀𝜀𝑐𝑐 = 𝜀𝜀1𝑐𝑐

𝑑𝑑1−𝑐𝑐< 𝜖𝜖𝑐𝑐𝑐𝑐

Where, 𝜀𝜀1 = 𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒

𝐸𝐸 =𝐸𝐸𝑝𝑝 .𝐴𝐴𝑝𝑝𝑒𝑒 . (𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒) + 𝑃𝑃𝑒𝑒

0.85 𝑓𝑓𝑐𝑐′ 𝛽𝛽1 𝑏𝑏

For a rectangular section

𝐸𝐸 =𝐸𝐸𝑝𝑝 .𝐴𝐴𝑝𝑝𝑒𝑒 . (𝜀𝜀𝑔𝑔𝑐𝑐 𝜀𝜀𝑝𝑝𝑒𝑒) + 𝑃𝑃𝑒𝑒 0.85𝑓𝑓𝑐𝑐′ 𝑝𝑝 𝑏𝑏 𝑏𝑏𝑤𝑤

0.85 𝑓𝑓𝑐𝑐′ 𝛽𝛽1 𝑏𝑏𝑤𝑤

For a flanged section

Calculate the nominal moment capacity of the section, 𝑀𝑀𝑛𝑛

For a flanged section

𝑀𝑀𝑛𝑛 = �𝑖𝑖=1

𝑖𝑖=𝑚𝑚

𝐸𝐸𝑝𝑝 𝑠𝑠𝑖𝑖 𝐸𝐸𝑝𝑝 𝜀𝜀𝑖𝑖 𝑑𝑑𝑖𝑖𝛽𝛽1𝐸𝐸

2+ 𝑃𝑃𝑒𝑒 𝑑𝑑𝑝𝑝

𝛽𝛽1𝐸𝐸2

+0.85 𝑓𝑓𝑐𝑐′ 𝑝𝑝 𝑏𝑏 𝑏𝑏𝑤𝑤𝛽𝛽1𝐸𝐸

2𝑝𝑝

For a rectangular section, use the same eqn. with 𝑏𝑏𝑤𝑤 = 𝑏𝑏

M-102 over Plum Creek: Design

Twin 75’ long single span structures, using 33” x 48” side by side box beams prestressed with CFCC

Determination of number of the theoretical number of CFCC strands based on calculation of excess tension in bottom flange based on Service III limit state:

Allow for 0 tension in bottom flange at service, as opposed to allowable

CFCC strand data based on testing:

GUTS = 60.70 kipsAstrand = 0.179 in2

f’pu = 339 ksi – calculated ultimate tensile strengthCE = 0.90 – environmental factor per ACI 440.1R-06fpu = 305 ksi – design ultimate tensile strengthEps = 21,000 ksi

Assume strand eccentricity based on strand center of gravity is between two rows of strands, and equal number of strands in each row:

Strand stress limit prior to transfer:

Assume 25% losses, and calculate the number of strands to start, then refine design based on service and strength limit state checks:

Need to develop jacking forces to stay below creep-rupture curve, while efficiently providing force to offset excess tension due to applied loads

M-102 over Plum Creek: Fabrication

15.2 mm strand reels – 1043 m each

Coupled strands, pull steel strands

Monitoring force in strands via load cells

Strand stressing complete, pouring concrete

Reinforcement complete, finishing concrete pour

Completed beam – no release stress cracking

M-102 over Plum Creek: Deck casting

M-102 over Plum Creek: Completed structures

MDOT/Lawrence Technological University MathCAD Templates:

https://mdotjboss.state.mi.us/SpecProv/trainingmaterials.htm

High-Strength Stainless Steel (HSSS)Prestressed Concrete (PC)

Will Potter

Florida Department of Transportation

Material Development

• Research• Georgia Tech• University of South Florida

• Materials Evaluated• Austenite - 316, 304 and XM-29• Duplex 2101, 2205 and 2304, • Martenistic 17-7

• Current Production Material • Duplex 2205

Moser et al, 2012

Duplex 2205Provides highest strength and best corrosion resistance among those evaluated

Duplex 2205Mechanical Properties

Duplex 2205 Alloy ASTM A416 PC Strand CFRP

Diameters (in) 0.375 to 0.7* 0.375 to 0.7 0.375 to 0.7**

Tensile Strength (ksi) 240 to 250 250, 270, 300+ 300+

Elongation @ UTS

Duplex 2205 –Material Testing

• Mechanical Properties w/ Wedge Chucks

• Initial Stress Limitations (constructability and design)• 60-65% fpu (conventional steel 75% fpu)

Al-Kaimakchi, 2019

Duplex 2205Material Testing

• Transfer and Development Length Testing• AASHTO equations are conservative

• Bond Strength• ASTM A1081

• Prestress Losses• AASHTO equations are adequate

17.8 kip – average 15.8 kip – minimum

ASTM A1081

Al-Kaimakchi, 2019

Paul, A. 2017 and Al-kaimakchi, 2019

Constructability• Conventional stressing methods

• Conventional detensioning methods

• Limit initial stress

Brown, 2018 Brown, 2018

HSSS-PC Piling

Initial Implementation

Coastal StatesGeorgiaFloridaVirginia

Louisiana

Moser, 2012

St. George Island, FL

HSSS-PC Piling

Projects

Brown, 2018

Sprinkel, 2018 Paul, A, 2015

Cornelius, 2019

Standardization in Florida- Piling -

• Specifications• Design Guidance • Design Standards

FDOT Structures Design Manual

FDOT Material Specifications

Piling Design Standards

HSSS-PC Flexural Members

• NO official flexural design guidance, currently• Limited research evaluating flexural design with HSSS• Ohio DOT – adjacent box beam brdige

️️

Al-Kaimakchi, 2019

Flexural Design Considerations

• Conventional steel strands• Yielding of strands followed by

crushing of concrete ( cu = 0.003)

• Stainless steel strands• Crushing of concrete

• cu = 0.003, pu < 0.014

• Balanced Condition • cu = 0.003, pu = 0.014

• Strand rupture• cu < 0.003, pu = 0.014

• Strength Resistance Factors?

Strain Compatibility Design Approach

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02

Strain (in./in.)

Stainless steel strands

Prestress Strainafter losses

Available Strain

Initial Strain0.65 fpu

Efforts to Develop Overall Design Guidance

• Georgia Tech – complete• Primary evaluation of piling with limited

evaluation of flexural design

• FAMU/FSU – active research• Investigating flexural behavior• Developing predictive analytical models• Developing design guidance

• NCHRP – upcoming research

• Planned Guidance Options (based on above research)• AASHTO Guide Specification for Bridge Design

with Stainless Steel Strand• Incorporate into AASHTO Bridge Design

Specification

References

• Al-kaimakchi, A. 2019. Flexural Beam Testing Program for Stainless Steel Strands. PCI Committee Days Presentation.

• Brown, K. 2018. Production of Prestressed Concrete Piles Using Stainless Steel. ASPIRE Magazine. P30-32.

• Cornelius, J. 2019. Prestressing Steel – New and Existing Products Overview. PCI Committee Days Presentation.

• Moser et al. 2012. Durability of Precast Prestressed Concrete Piles in Marine Environment, Part 2, Volume 2: Stainless Steel Prestressing Strand & Wire. GDOT Project No. 10-26, Task Order No. 02-78.

• Paul, A. L. F. Kahn, and K. E. Kurtis. 2015. Corrosion-Free Precast Prestressed Concrete Piles Made with Stainless Steel Reinforcement: Construction, Test and Evaluation. Report no. FHWA-GA-15-1134. Atlanta: Georgia Institute of Technology.

• Paul, A. L. B. Gleich, L. F. Kahn. 2017. Structural Performance of Prestressed Concrete Bridge Piles Using Duplex Stainless Steel Strands. ASCE Journal of Structural Engineering.

• Paul, A. L. B. Gleich, L. F. Kahn. 2017. Transfer and development length of high-strength duplex stainless steel strand in prestressed concrete piles. PCI Journal May-June 2017.

1. Introduction of current needs in bridge durability & Advanced Structural Materials of interest (Matthew Chynoweth)

2. CFRP-PC Design guidance & standards documents (Matthew Chynoweth)

3. HSSS-PC Design guidance & standards documents(Will Potter)

4. UHPC Design guidance & standards documents(Kyle Riding)

5. FRP-RC Design guidance & standards documents (Antonio Nanni)

6. Life-Cycle Cost analysis strategies(Antonio Nanni)

7. Moderated Question & Answer(Steven Nolan)

Ultra-High Performance Concrete

“UHPC is limited to concrete that has a minimum specified compressive strength of 22,000 psi (150 MPa) with specified durability tensile ductility and toughness requirements; fibers are generally included to achieve specified requirements. UHPC typically exhibits elastic-plastic or strain-hardening characteristics under uniaxial tension and has a very low permeability due to its dense and discontinuous pore structure.” -ACI 239

Precast/ Prestressed Concrete Institute (PCI) is going to define UHPC as concrete with 18 ksi compressive strength

Map of Known UHPC Bridge Projects

https://usdot.maps.arcgis.com/apps/webappviewer/index.html?id=41929767ce164eba934d70883d775582

Benefits of UHPC

Tensile performance can allow you to reduce amount of steel reinforcementCan optimize geometry for lighter member to reduce shipping costs and crane sizeReduce cover dimensions?Dense and discontinuous microstructure can give very high durability – alternative to stainless steel and FRP reinforcement

UHPC Application Example: Connections & Repair

Mixing – high energy needed Placing Curing(long mixing time or high shear mixer needed)

UHPC Application Example: Piles

UHPC Application Example: Potential Pile Shapes

Hollow PilesH-Piles

Geometry optimized to reduce weight and material use, increase skin friction

Tested in 2008 – see Voort, Suleiman, and Sritharan, Design and Performance Verification of Ultra-High Performance Concrete Piles for Deep Foundations

Maher Tadros, PCI Presentation 2018

UHPC Application Example: Piles

Picture courtesy of Miles Zeeman

UHPC Pile Driving Test100 ft. Test pile driven in Leesburg, FL

UHPC Application Example: Segmental Construction

Pedestrian Bridge in Medellin, Colombia Built in 2017 First Bridge in Colombia made from UHPCSaved 30% compared to alternative steel designCurrently constructing 2nd bridgeAlso adapting UHPC for pavement overlays

17400 psi (120 MPa) concrete

UHPC Application Example: Segmental Construction

361 ft long bridge4 spansMain Span is 141 ft. long29 precast segments, 10 tons each24 post-tension cables

Nunez, Patino, Arango, and Echeverri, “REVIEW ON FIRST STRUCTURAL APPLICATIONS OF UHPC IN COLOMBIA,” Second International Interactive Symposium on UHPC, Albany, NY., June 2-5, 2019, Paper 118.

UHPC Application Example: Hybrid Girders

Figure courtesy of Eduardo Torres and Trey Hamilton

Self-Consolidating Concrete

UHPC used on end-regions to reduce end-cracking, and potentially allow for longer spans

Fresh Property Testing: Flow TestingASTM C1856 – use ASTM C1437 flow table and cone, without base and without performing dropsMeasure the flow 120 ± 5 s after lifting mold to nearest 1 mm (ave. of 2 measurements)

Recommendation: 8 to 14 in. flow diameter (Wille 2011)

Stress-Strain Relationships

c,y c,u

Compressive Stress-Strain Behavior

Tensile Stress-Strain Behavior

Based on ACI 239R18 Based on FHWA-HIF-13-032

Constitutive Relationships and Ultimate Limit State for UHPC with Macro-Reinforcement

Concrete

Beam FBD Strain

Figures based on ACI 239R18

Stress from Stress-Strain Relationship Forces

24-hour 4-day 7-day 28-dayBefore traffic opening

Alabama 14 (97) 21 (145) 14 (97)Delaware 14 (97)Idaho 14 (97) 20, 25 (138, 172)*Iowa 10 (69) 15 (103)Maine 21 (145)

Michigan 15 (103)

Nebraska 21 (145)New Jersey 5.7 (39) 11.6 (80) 14.5 (100)New Mexico 14 (97) 21 (145)New York 12 (83) 21 (145)Texas 14 (97) 21 (145)West Virginia 12 (83) 15 (103)Ontario 11.6 (80) 18.9 (130)

Canada17.4, 21.7 (120, 150)†

France18,850-36,300 (130-250) +

Switzerland 17.4 (120)

Compressive Strength Requirement

Values given in psi (MPa)

ASTM C1856 modifies ASTM C39 to use 3 × 6 in. cylinders

Tensile strength Flexural strengthFlexural Tough.

ksi (MPa) ksi (MPa) ASTM C1018

Alabama AASHTO T 198, 1.0 (6.9) splitting

Delaware

Idaho ASTM C293, 2 (14)IowaMichiganNew Jersey I30New MexicoNew York I30Texas I30

Ontario ASTM C1609, 2.2 (15)

Canada 0.58, 0.73 (4, 5), direct tension

0.58, 0.73 (4, 5) with inverse analysis

Tensile Strength Requirement

Qualification Tensile Testing Direct Tension Test ASTM C1609 modified by ASTM C1856

Friction in support conditions can increase flexural capacity 30-60% (Wille and MontesinosWille, K., & Parra-Montesinos, G. (2012). Effect of beam size, casting method, and support conditions on flexural behaviour of UHPFRC. ACI Materials Journal, 109(3), 379–388.)

Direct Tension Test Direct Tension Test Samples After Testing

0 0.005 0.01 0.015 0.02

Strain

Average

2 × 2 × 17 in. samples

Durability RequirementsProperty

Chloride Ion Penetrability Shrinkage

Chloride Ion Penetrability Scaling

Resistance

Freeze-Thaw Abrasion Resistance Alkali-Silica

Reactivity(coulombs) (microstrain) (oz/ft3) (RDM %) (oz.)

Test Method ASTM C1202/ AASHTO T 277 ASTM C157 AASHTO T259 ASTM C672

ASTM C666A, 600 cycles

ASTM C944, 2x weight ASTM C1260

Alabama T160 < 0.026

Delaware <0.07, ½ in. (13mm) depth y < 3 > 95% 0.08%, test at 28

Idaho < 250 < 765, initial reading after set

< 0.07, 1/4th in. (6mm) depth y < 3 > 96% < 0.025, ground

surface

ASTM C1567, < 0.10%, test at 28 days

New Jersey <1.0, ½ in. (13mm) depth y < 3 > 96% < 0.03 Innocuous, test at

28 days

New Mexico <0.059, ½ in. (13mm) depth No scaling > 99%, 300 cycles < 0.026 < 0.10%,

Innocuous

New York reading after set< 0.07, 1/5th in. (5mm) depth y < 3 > 96% < 0.025, ground

surfaceInnocuous, test at 28 days

Texas y < 3 > 96%, 300 cycles < 0.1%

Canada <500, <300, <100

X (different method)

CSA A23.2-22C 0.4,0.2,0.1 kg/m2 <5, <1, <0.5 g

Design-Related Properties

Creep coefficient (ACI 239R18)0.31 (steam cured)0.8 (non-heat cured)

Negligible shrinkage after heat curingElastic Modulus: 6000 to 7200 ksi (function of fibers and fc)

https://www.fhwa.dot.gov/publications/lists/022.cfm

FHWA has published many reports on UHPC:

Options for UHPCPre-blended, prebagged, proprietary UHPC

Comes with support from manufacturerProven resultsHigh cost ($2000-3000/yd3)

Make-your-own UHPC with local materialsHigh knowledge base needed (can hire consultants to help)Can get 18-22ksi with local materials without too much difficultyCan save 30-74%1 from cost of preblended materialsGuidelines/ papers on how to make UHPC with local materials

Development of ultra-high performance concrete with locally available materials https://doi.org/10.1016/j.conbuildmat.2016.12.040Development of Cost-Effective Ultra-High Performance Concrete (UHPC) for Colorado’s Sustainable Infrastructure 1Ultra-high performance concrete with compressive strength exceeding 150 MPa (22 ksi): a simpler way DOI: 10.14359/51664215Design and per Design and performance of cost-eff formance of cost-effective ultra-high per a-high performance formanceconcrete for prefabricated elements https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3587&context=doctoral_dissertations

Biggest cost is fibersMade in USA steel fibers available

1 Kim, “Development of Cost-Effective Ultra-High Performance Concrete (UHPC) for Colorado’s Sustainable Infrastructure,” Final Report, CDOT-2018-15, 2018.

Implementation ChallengesHigh amount of QC needed, especially for fiber distribution, orientation, and plant-ready tensile testExperienced contractors/ precasters needed

Placement direction impacts fiber alignment & tensile strength

Mixing time 15-30 minutes, much shorter with high shear mixerWorking time is short – once you stop agitating it, can lose workability rapidly and form “elephant skin”New UHPC does not bond well to old UHPCStructural design equations made for conventional concrete can work, but don’t fully take advantage of UHPC (ie. Creep, development length, etc.)Most durability testing done on UHPC with fc’ >150 ksiSpecifications need to catch up with material

Example of specifications that need updating: ACI 318-19 Air Entrainment Requirements

Nominal Max. Agg. Size (in.)

Target Air Content, F1 (%)

Target AirContent, F2 & F3 (%)

3/8 6.0 7.5

1/2 5.5 7.0

3/4 5.0 6.0

1 4.5 6.0

1-1/2 4.5 5.5

2 4.0 5.0

3 3.5 4.5

FRP-RC Design Guidance & Standards Documents

+ Life-Cycle Cost analysis strategies

TRB Webinar Date: December 3, 1:00-2:30pm ESTModerator: Steven Nolan

Presenter: Antonio NanniUniversity of Miaminanni@Miami.edu

1. Introduction of current needs in bridge durability & materials of interest• CFRP & HSSS prestressing; FRP rebar;

2. CFRP-PC Design guidance & standards documents (Matthew Chynoweth)• Costs and Design tools• Implementation challenges

3. HSSS-PC Design guidance & standards documents (Will Potter)• Costs and Design tools• Implementation challenges

4. UHPC Design guidance & standards documents (Kyle Riding)• Costs and Design tools• Implementation challenges

5. FRP-RC Design guidance & standards documents (Antonio Nanni)• Costs and Design tools• Implementation challenges

6. Life-Cycle Cost analysis strategies (Antonio Nanni)• ASM comparisons and synergies• Future enhancements or needs

7. Moderated Question & Answer(Steven Nolan)

OF Contents

· Problem Statement· FRP Materials and Design Properties· Guides, Standards and Specs· Where to use GFRP· What do we still need· Field Applications in Florida· Cost Justification (Service Life, LCC & LCA)· Conclusions

4SERVICE LIFE GREATLY REDUCED BY CORROSION

Problem Statement• Cause of failure for structures

exposed to aggressive environments is often corrosion of steel reinforcement

• Chlorides from de-icing salts or seawater penetrate concrete and reach steelü via cracks ü via concrete porosity

• Corrosion is accelerated by carbonation that lowers concrete pH

Traditional corrosion mitigation efforts center on keeping chlorides from getting to reinforcing steel or simply delaying the diffusion time

State-of-Practice

• Admixtures• Increase Concrete Cover• Alter Concrete Mix• Membranes & Overlays• Epoxy-Coated, Galvanized

or Stainless Steel

5DELAYING SYMPTOMS RATHER THAN CURING DISEASE

Photo: Courtesy of TxDOT

OF Contents

FRP Bars, Strands and Grids Typically produced by the Pultrusion process

Production Process (Pultrusion)

Factors Affecting Material Characteristics

• Fiber volume• Type of fibers• Type of resin• Fiber orientation• QC during manufacturing• Rate of curing• Void content• Service temperature

Tensile Behavior• Tensile properties obtained from bar manufacturer• Manufactures must report a guaranteed tensile strength f*fu, as

mean tensile strength minus three standard deviations

• Similarly, a guaranteed rupture strain

Critical Design Provisions

Flexural Resistance

Shear Resistance

GFRP Design Tensile Strength

Ultimate capacity provisions:

Critical Design Provisions

GFRP Creep Rupture Strength

GFRP Fatigue Strength

Spacing for Crack Control

Fatigue and serviceability provisions:

Evaluation of Durability: Selected Bridges• Eleven bridges located across the United States• Each bridge contains GFRP bars in deck or other location

and has been in service for at least 15 years

• Gills Creek Bridge (VA)• O’Fallon Park Bridge (CO)• Salem Ave Bridge (OH)• Bettendorf Bridge (IA)• Cuyahoga County Bridge (OH)• McKinleyville Bridge (WV)• Thayer Road Bridge (IN)• Roger’s Creek Bridge (KY)• Sierrita de la Cruz Creek Bridge (TX) • Walker Box Culvert Bridge (MO)• Southview Bridge (MO)

Sierrita de la Cruz Creek Bridge, Texas • Location: 25 miles northwest Amarillo, TX• Agency: Texas DOT• Year Built: 2000• Geometry: 7 spans, 553 ft. long, 45 ft. wide• Bridge Type: GFRP deck top mat, concrete deck on PC girders

Selected Bridges (Example)

GFRP Tests: Modified Tensile Strength Test• Extracted and virgin coupons were tested in tension• Virgin new generation full-size bars were also tested in tension

• The results of virgin full-size bars from tensile tests performed in 2000 were used for comparison

• A correlation was calculated to determine the tensile strength of the extracted bars

Sample Full-sizeStrength, psi

CouponStrength, psi

Coupon to Full-size

Pristine 119,318 96,997 18.71%

Extracted Bars 113,840a 90,110 20.84%

Difference due to degradation % 2.13%

Note: a = Tested in 2000

OF Contents

· Problem Statement· FRP Materials and Design Properties· Guides, Standards and Specs

ACI and ASTMAASHTO, Florida DOT, and Texas DOT

· Where to use GFRP· What do we still need· Field Applications in Florida· Cost Justification (Service Life, LCC & LCA)· Conclusions

How To Specify for Building Structures

SPECIFYING AND CONSTRUCTING WITH GFRP BARS17

Update on AASHTO Activities related to FRP bars for Bridge Structures

Harmonize with national (ACI, ASTM and AASHTO-BDS) andinternational (CSA) specifications.

• Ease design/deployment• Ease certification• Enlarge market

Update existing provisions to reflect better materials andmanufacturing, and new research findings.

• Make design more efficient

Expand provisions to include all members of a bridge.

• Allow the design of a bridge entirely GFRP-RC

Approach and Relevance of expanded 2018 AASHTO Guide Spec.

Comparison of Critical Design ParametersAASHTO 2nd 2018

AASHTO 1st 2009

ACI 440 Code 2021?

ACI 440.1R2015

ffu* 99.9 99.9 99.9 99.9 Strength percentileC 0.75 0.65 0.65 0.65 Res. fact. concr. failureT 0.55 0.55 0.55 0.55 Res. fact. FRP failureS 0.75 0.75 0.75 0.75 Res. fact. shear failure

CE 0.70 0.70 0.90 0.70 Environm. reductionCC 0.30 0.20 0.30 0.20 Creep rupt. reductionCf 0.25 0.20 n/a 0.20 Fatigue reductionCb 0.83 0.70 0.70 to 0.83 0.70 Bond reductionw 0.027 0.0200 0.027 0.020 to 0.027 Crack width limit [in.]

cc,stirrup 1.5 1.5 2.0 2.0(1) Clear cover [in.]cc,slab 1.0 0.75 to 2.0 0.75 to 2.0 0.75 to 2.0(1) Clear cover [in.]shear 0.004 0.004 0.004 0.004 Strain limit in shear

(1) ACI 440.5-08 Table 3.1To be finalized

• Mandatory Specs• Uniform Approval Processes

- Manufacturer Approval vs. Product Approval• Design Tools

Design Guidance & Tools: Florida DOT

https://www.fdot.gov/structures/innovation/FRP.shtm

• Uniform Approval Processes- Manufacturer Approval & Certification vs. Product Approval

https://mac.fdot.gov/smoreports

• Need for Accessible & Reliable Design Tools- Commercial vs. Agency/Institution based design programs

https://www.fdot.gov/structures/proglib.shtm

** Available on request

CFRP-PC (w/ GFRP-RC Shear) Beta version **

GFRP-RC Alpha version **

GFRP-RC included (3b)

GFRP-RC in development !

Example of other DOT Activities related to FRP bars.

Texas DOT:Update of bridge deck design using GFRP Top Mat in accordance with 2018 AASHTO Guide Spec

Texas DOT: top-mat GFRP reinforcement

Ohio DOT: Bridge deck GFRP reinforcement

Maine DOT: Bridge deck GFRP reinforcement

Other Active DOTs in the use of FRP bars

OF Contents

• Concrete members susceptible to steel corrosion by chlorides or

• low concrete pH• Concrete members requiring non-

ferrous reinforcement due to electro-magnetic considerations

• Need of thermal non-conductivity

Where Should FRP be Used?

ALTERNATIVE TO EPOXY, GALVANIZED AND STAINLESS STEEL REBAR

• Seawalls, Piles and Piers• Marine Structures• Bridge Decks • Traffic Railings• Approach Slabs• Barrier / Retaining Walls• Culverts• Sewage System Tunneling• Parking Garages

Infrastructure Applications

OF Contents

What do we still need? Refinement of conservative Design Limits

To be finalized

What do we still need? Gaps in Design & Deployment

• Connections (post-installed & couplers)

• Fatigue limits• Elastic modulus• Bent bars• Scalability of production

1700+ adhesive-dowelled anchors (HRB 2019)

OF Contents

Project Examples: FAST FACTS

Fast-Facts: https://www.fdot.gov/structures/innovation/FRP.shtm#link9

Homosassa, FL 2017-19 (GFRP-RC & CFRP-PC) Five-span vehicular bridge

July 16, 2019

Fast-Facts: https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/structures/innovation/fastfacts/fastfacts-430021-1.pdf

Project Examples: HALLS RIVER BRIDGE

Six-man crew can assemble complete bent cap GFRP rebar cage in 4.5 hours

Project Examples: HALLS RIVER BRIDGE

University of Miami – Completed 2016:

Project Examples: INNOVATION PEDESTRIAN BRIDGE

Fast-Facts: https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/structures/innovation/fastfacts/fastfacts-innovationbridge-um.pdf

Elevation view of Innovation Bridge with BFRP reinforcement in the auger-cast-piles, bent-caps, double-tee stems and flanges, deck overlay and curbs

CIP continuous flat-slab bridge under construction 2019:

Project Examples: NE 23RD AVE overIBIS WATERWAY

Fast-Facts: https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/structures/innovation/fastfacts/fastfacts-434359-1.pdf?sfvrsn=175168c2_2

2016 conditions prior to 5,000’ of Secant-Pile Wall construction (2019)

Remains left after Hurricane Matthew destructive forces resulted in “wash-out” and destruction of the essential State Road A1A, which is an Evacuation Route

Project Examples: SR-A1A SECANT-PILESEAWALL

GFRP-CAGES AT WORK

Seawall’s auger-cast concrete secant-piles are 36-inch (910 mm) diameter. Primary piles are 36-feet (11 m) in length and are reinforced with 25 ~ #8 GFRP bars.

Fast-Facts: https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/structures/innovation/fastfacts-440557-7.pdf?sfvrsn=73e5bc6a_2

Project Examples: SR-A1A SECANT-PILESEAWALL

OF Contents

LCC & LCA also can show the sustainable (economic and environmental) advantage of FRP-RC structures in the coastal environment:

Cost Justification (Service Life, LCC & LCA)

Example: LCC & LCA Comparison of Carbon Steel-RC/PC versus FRP-RC/PC (various effective discount rate), adapted from Cadenazzi et al. 2019 42

CS-RC/PC Bridge Replacement

FRP-RC/PC Bridge Replacement

Younis et al., 2018: Carbon-Steel vs. SSR vs. GFRP rebar

https://doi.org/10.1016/j.conbuildmat.2018.04.183

(Baseline scenario with discount rate = 0.7%)

RC1 = Traditional concrete mix with carbon-(black) steel rebar;RC2 = Traditional concrete mix with SS rebar;RC3 = Concrete with seawater & RCA with GFRP rebar.

Performance as a function of maintenance:

CS-RC/PC alternative SS or FRP-RC/PC alternativesCadenazzi, T., Dotelli, G., Rossini, M., Nolan, S., and A. Nanni. (2019). Cost and Environmental Analyses of Reinforcement Alternatives for a Concrete Bridge. Structure and Infrastructure Engineering 44

CE effect

www.ASCEgrandchallenge.com“Reduce the life cycle cost of infrastructure by 50% by 2025 and foster the optimization of infrastructure investments for society”

Rebar Example Cost Comparisons:

• Cost information based of Contractor bid prices• Price of epoxy reinforcing @ $1.00/LB

Anthony Wayne Trail over NSRR Cost Per Square Foot of Deck

Epoxy Coated Reinforcing $8.052/SF

GFRP Reinforcing (GFRP 1st Edition) $9.587/SF

GFRP Reinforcing (GFRP 2nd Edition) $8.736/SF

• Cost information is from Engineer’s estimate• Price of epoxy reinforcing @ $1.15/LB• Recent increase in steel cost (15%-20% Increase)

• Result in more competitive costs

Industrial Drive over the Maumee River

Cost Per Square Foot of Deck

Epoxy Coated Reinforcing $11.805/SF

GFRP Reinforcing $10.609/SF

Rebar Example Cost Comparisons:

OF Contents

· Problem Statement· FRP Materials and Design Properties· Guides, Standards and Specs· Where to use GFRP· What do we still need· Cost Justification (Service Life, LCC & LCA)· Field Applications in Florida· Conclusions

Conclusions

• Complete set of guides, test methods and standards available for GFRP bars

• Many structures successfully built with GFRP bars and performing well• Non-proprietary solutions, traditional supply chain acquisition &

installation available• Extended service life of GFRP reinforced concrete ensured • Current practices adopted for corrosion protection are unnecessary with

GFRP reinforcement• New frontiers to be explored to improve resilience and sustainability

Thank you for your attention!

The End

Today’s Speakers• Steven Nolan, Florida DOT,

steven.nolan@dot.state.fl.us• Matt Chynoweth, Michigan DOT,

ChynowethM@michigan.gov• William Potter, Florida DOT,

William.Potter@dot.state.fl.us• Kyle Riding, University of Florida,

kyle.riding@essie.ufl.edu• Tony Nanni, University of Miami,

nanni@miami.edu

Get Involved with TRB• Getting involved is free!• Join a Standing Committee (http://bit.ly/2jYRrF6)• Become a Friend of a Committee

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