Bond Behavior of Straight and Bent Glass Fiber–Reinforced Polymer Bars at Elevated Temperatures: Pull-Out Tests and Numerical Simulations
Publication: Journal of Composites for Construction
Volume 26, Issue 3
Abstract
The bond between concrete and fiber-reinforced polymer (FRP) bars is severely degraded when the glass transition temperature of the FRP (set mainly by the polymeric matrix, typically a thermosetting resin) is approached, and therefore long development lengths are required to enable a proper anchorage in cooler zones of FRP–reinforced concrete (RC) members exposed to fire. In spite of the potential of bent bars to shorten such lengths, and thereby improve the fire resistance of FRP–RC members, very few studies have addressed the effects of elevated temperatures on the bond performance of bent FRP reinforcement. This paper presents experimental and numerical investigations concerning the bond behavior of straight and 90°-bent glass-FRP (GFRP) bars at elevated temperatures. Steady-state pull-out tests were first carried out on bent ribbed bars, from 20°C up to 300°C, and the results were compared with those previously obtained from straight bars. The experiments showed that the hook effect provided by the bend and tail lengths of the bars enabled bond-strength increases of between 30% and 90% compared with straight bars. Three-dimensional finite-element models were then developed to: (1) simulate the pull-out tests; and (2) perform design-oriented parametric studies, aimed at assessing the influence of elevated temperatures on the anchorage strength of straight bars with different surface finishes (sand-coated and ribbed), and of 90°-bent ribbed bars with varying tail and straight development lengths. Temperature-dependent local bond stress versus slip laws were implemented in the models in order to describe the bond interaction along the straight and bent lengths of the bars. The models provided a good agreement with the test data, in terms of load versus slip response, and a reduction in pull-out load and bond stiffness with temperature. The findings were that: (1) the adoption of 90°-bent anchorages with appropriate tail lengths is an effective and practical approach for improving the bond strength of GFRP bars at both ambient and elevated temperatures; and (2) at elevated temperatures, to mobilize the tensile strength of GFRP bars, the development lengths of straight and bent bars designed for ambient temperature must be significantly increased. Finally, optimal anchorage lengths are proposed, as a function of temperature, for beam and slab applications.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors wish to acknowledge FCT (project FireComposite PTDC/ECM-EST/1882/2014) and CERIS for funding the research, Secil and Unibetão for supplying the concrete, Schöck for supplying the GFRP bars and Sika for supplying the bicomponent resin. The first author also wishes to thank FCT for their financial support through the SFRH/BD/129681/2017 scholarship.
References
Abbasi, A., and P. J. Hogg. 2006. “Fire testing of concrete beams with fibre reinforced plastic rebar.” Composites, Part A 37 (8): 1142–1150. https://doi.org/10.1016/j.compositesa.2005.05.029.
ACI (American Concrete Institute). 2011. Building code requirements for structural concrete. ACI 318-11. Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2015. Guide for the design and construction of structural concrete reinforced with FRP bars. ACI 440.1R-15. Farmington Hills, MI: ACI.
Ahmed, E. A., B. Benmokrane, and M. Sansfaçon. 2017. “Case study: Design, construction, and performance of the La Chancelière parking garage’s concrete flat slabs reinforced with GFRP bars.” J. Compos. Constr. 21 (1): 05016001. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000656.
ASTM. 2014. Standard test method for bond strength of fiber-reinforced polymer matrix composite bars to concrete by pullout testing. ASTM D7913/D7913M-14. West Conshohocken, PA: ASTM.
Azevedo, A., C. Tiago, J. P. Firmo, and J. R. Correia. 2021. Development of a Matlab code for the numerical modelling of the bond between FRP composites and concrete. CERIS Rep. DTC no 05/2021.
Bažant, Z. P., and F. Lin. 1988. “Nonlocal smeared cracking model for concrete fracture.” J. Struct. Eng. 114 (11): 2493–2510. https://doi.org/10.1061/(ASCE)0733-9445(1988)114:11(2493).
Benmokrane, B., E. El-Salakawy, Z. Cherrak, and A. Wiseman. 2004. “Fibre reinforced polymer composite bars for the structural concrete slabs of a Public Works and Government Services Canada parking garage.” Can. J. Civ. Eng. 31 (5): 732–748. https://doi.org/10.1139/l04-049.
Bilotta, A., A. Compagnone, L. Esposito, and E. Nigro. 2020. “Structural behaviour of FRP reinforced concrete slabs in fire.” Eng. Struct. 221: 111058. https://doi.org/10.1016/j.engstruct.2020.111058.
Carvelli, V., M. A. Pisani, and C. Poggi. 2013. “High temperature effects on concrete members reinforced with GFRP rebars.” Composites, Part B 54 (1): 125–132. https://doi.org/10.1016/j.compositesb.2013.05.013.
CEN (European Committee for Standardization). 2009a. Testing hardened concrete - part 3: Compressive strength of test specimens. EN 12390-3. Brussels, Belgium: CEN.
CEN (European Committee for Standardization). 2009b. Testing hardened concrete - part 6: Tensile splitting strength of test specimens. EN 12390-6. Brussels, Belgium: CEN.
CEN (European Committee for Standardization). 2010a. Design of concrete structures - part 1-2: General rules - Structural fire design. Eurocode 2. EN 1992-1-2. Brussels, Belgium: CEN.
CEN (European Committee for Standardization). 2010b. Design of concrete structures - part 1-1: General rules and rules for buildings. Eurocode 2. EN 1992-1-1. Brussels, Belgium: CEN.
Duarte, A. P. C., B. A. Silva, N. Silvestre, J. de Brito, E. Júlio, and J. M. Castro. 2016. “Finite element modelling of short steel tubes filled with rubberized concrete.” Compos. Struct. 150: 28–40. https://doi.org/10.1016/j.compstruct.2016.04.048.
Eligehausen, R., E. P. Popov, and V. V. Bertero. 1983. Local bond stress-slip relationships of deformed bars under generalized excitations. UCB/EERC-83/23. Washington, DC: National Science Foundation.
FIB (International Federation for Structural Concrete). 2007. FRP reinforcement for RC structures. Bulletin 40. Lausanne, Switzerland: FIB.
Hajiloo, H., and M. F. Green. 2018. “Bond strength of GFRP reinforcing bars at high temperatures with implications for performance in fire.” J. Compos. Constr. 22 (6): 04018055. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000897.
Hajiloo, H., M. F. Green, M. Noël, N. Bénichou, and M. Sultan. 2019. “GFRP-reinforced concrete slabs: Fire resistance and design efficiency.” J. Compos. Constr. 23 (2): 04019009. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000937.
Hilsdorf, H. K., and W. Brameshuber. 1991. “Code-type formulation of fracture mechanics concepts for concrete.” Int. J. Fract. 51 (1): 61–72. https://doi.org/10.1007/BF00020853.
ISO. 1996. Textile-glass-reinforced plastics - Prepregs, moulding compounds and laminates - Determination of the textile-glass and mineral-filler content - Calcination methods. ISO 1172. Geneva: ISO.
Katz, A., N. Berman, and L. C. Bank. 1999. “Effect of high temperature on bond strength of FRP rebars.” J. Compos. Constr. 3 (2): 73–81. https://doi.org/10.1061/(ASCE)1090-0268(1999)3:2(73).
Kiari, M., T. Stratford, and L. A. Bisby. 2015. “New design of beam FRP reinforcement for fire performance.” In Proc., 5th Int. Workshop on Performance, Protection & Strengthening of Structures under Extreme Loading, edited by Venkatesh K. R. Kodur, and N. Banthia, 764–771. Lancaster, PA: DEStech Publications, Inc.
Kiari, M., T. J. Stratford, and L. A. Bisby. 2016. “New approach to fire safe application of fibre-reinforced polymer reinforcement for concrete.” In Proc., 7th Int. Conf. on Advanced Composite Materials in Bridges and Structures. Vancouver, BC: University of British Columbia.
Kiari, M., E. Triantafyllidou, S. Grosu, T. Stratford, and L. Bisby. 2013. “Design of an FRP-reinforced concrete beam system for fire performance.” In Advanced Composites in Construction 2013, edited by C. J. Whysall, and S. E. Taylor, 145–154. Chesterfield, UK: NetComposites Limited.
Lopes, B., M. R. T. Arruda, L. Almeida-Fernandes, L. Castro, N. Silvestre, and J. R. Correia. 2020. “Assessment of mesh dependency in the numerical simulation of compact tension tests for orthotropic materials.” Composites, Part C 1: 100006. https://doi.org/10.1016/j.jcomc.2020.100006.
McIntyre, E. 2019. “Fire performance of fibre reinforced polymer (FRP) bars in reinforced concrete: An experimental approach.” Ph.D. thesis, Dept. of Civil Engineering, Univ. of Edinburgh.
Mouritz, A. P., and A. G. Gibson. 2006. Fire properties of polymer composite materials. Solid mechanics and its applications. Birkhauser, Switzerland: Springer.
Nigro, E., A. Bilotta, G. Cefarelli, G. Manfredi, and E. Cosenza. 2012. “Performance under fire situations of concrete members reinforced with FRP rods: Bond models and design nomograms.” J. Compos. Constr. 16 (4): 395–406. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000279.
Rosa, I. C., J. P. Firmo, J. R. Correia, and J. A. O. Barros. 2019. “Bond behaviour of sand coated GFRP bars to concrete at elevated temperature – Definition of bond vs. slip relations.” Composites, Part B 160: 329–340. https://doi.org/10.1016/j.compositesb.2018.10.020.
Rosa, I. C., J. P. Firmo, J. R. Correia, and P. Mazzuca. 2021. “Influence of elevated temperatures on the bond behaviour of ribbed GFRP bars in concrete.” Cem. Concr. Compos. 122: 104119. https://doi.org/10.1016/j.cemconcomp.2021.104119.
Rosa, I. C., T. Morgado, J. R. Correia, J. P. Firmo, and N. Silvestre. 2018. “Shear behaviour of GFRP composite materials at elevated temperature.” J. Compos. Constr. 22 (3): 04018010. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000839.
Rosa, I. C., P. Santos, J. P. Firmo, and J. R. Correia. 2020. “Fire behaviour of concrete slab strips reinforced with sand-coated GFRP bars.” Compos. Struct. 244: 112270. https://doi.org/10.1016/j.compstruct.2020.112270.
Schöck. 2013. “Schöck ComBAR - Technical information.” Technical datasheet.
Sena-Cruz, J., and J. Barros. 2004. “Modeling of bond between near-surface mounted CFRP laminate strips and concrete.” Comput. Struct. 82 (17–19): 1513–1521.
Sena-Cruz, J. M. 2005. “Strengthening of concrete structures with near-surface mounted CFRP laminate strips.” Ph.D. thesis, Dept. of Civil Engineering, Universidade do Minho.
SIMULIA. 2018. ABAQUS standard, user’s manual, version 2018. Johnston, RI: Dassault Systèmes.
Solyom, S., M. Di Benedetti, M. Guadagnini, and G. L. Balázs. 2020. “Effect of temperature on the bond behaviour of GFRP bars in concrete.” Composites, Part B 183: 107602. https://doi.org/10.1016/j.compositesb.2019.107602.
Stang, H., and T. Aarre. 1992. “Evaluation of crack width in FRC with conventional reinforcement.” Cem. Concr. Compos. 14 (2): 143–154. https://doi.org/10.1016/0958-9465(92)90007-I.
Veljkovic, A., V. Carvelli, S. Solyom, G. L. Balázs, and M. Rezazadeh. 2019. “Modelling the temperature effects at the interface between GFRP bar and concrete.” In IABSE Symp., Guimaraes 2019: Towards a Resilient Built Environment Risk and Asset Management - Report, 145–154. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE).
Weber, A. 2008. “Fire-resistance tests on composite rebars.” In Proc., 4th Int. Conf. of FRP Composites in Civil Engineering. Lausanne, Switzerland: Swiss Federal Institute of Technology (EPFL).
Yuan, J. S., and M. N. S. Hadi. 2018. “Friction coefficient between FRP pultruded profiles and concrete.” Mater. Struct. 51 (120): 1–10.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 26 • Issue 3 • June 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Aug 18, 2021
Accepted: Jan 15, 2022
Published online: Mar 21, 2022
Published in print: Jun 1, 2022
Discussion open until: Aug 21, 2022
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.
Cited by
- Inês C. Rosa, João P. Firmo, João R. Correia, Luke A. Bisby, Fire Behavior of GFRP-Reinforced Concrete Structural Members: A State-of-the-Art Review, Journal of Composites for Construction, 10.1061/JCCOF2.CCENG-4268, 27, 5, (2023).
- Inês C. Rosa, João P. Firmo, João R. Correia, Fire behaviour of GFRP-reinforced concrete slab strips. Effect of straight and 90° bent tension lap splices, Engineering Structures, 10.1016/j.engstruct.2022.114904, 270, (114904), (2022).