GFRP-Reinforced Concrete Slabs: Fire Resistance and Design Efficiency
Publication: Journal of Composites for Construction
Volume 23, Issue 2
Abstract
Thickening concrete cover to obtain an adequate fire resistance lowers the efficiency of glass fiber–reinforced polymer (GFRP) reinforcement and increases the cost relative to conventional steel reinforcement. This paper investigates the fire resistance of two full-scale GFRP-RC slabs with only 40 mm of clear concrete cover and 200 mm of unexposed (cool) anchor zone at the ends. Both slabs endured 3 h under the standard fire. The slabs were loaded with a sustained load, which caused a moment equal to 45% of their ultimate flexural strength. Emphasis was placed on studying the bond behavior of GFRP bars by comprehensively investigating temperature distributions particularly at the unexposed anchor zones at the ends of the slabs. The temperature reduces significantly in the unexposed zones, providing an adequate anchorage for the bars when almost the entire GFRP-to-concrete bond deteriorated in the exposed zone. The analysis of the experimental results showed that the increase in the tensile force in the GFRP bars during the standard fire is below 50% of the existing sustained force. A new model considers the bond degradation to predict the fire resistance of GFRP-reinforced slabs. The results enable an efficient, economic, and fire-safe application of GFRP reinforcement in concrete construction by reducing the concrete cover.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors would like to thank the Natural Sciences and Engineering Research Council of Canada (NSERC), Pultrall Inc., and BP Composites for financial and material support. The authors also appreciate the insightful advice of Dr. Benmokrane and the cooperation of Dr. Mohammad from Sherbrooke University. The authors thank the technical staff of the Fire Research Laboratory at NRC. The contribution of Dr. Gales is appreciated.
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). 2015. Guide for the design and construction of concrete reinforced with FRP bars. ACI 440.1R. Farmington Hills, MI: ACI.
ASTM. 2015. Standard test methods for fire tests of building construction and materials. ASTM E119. West Conshohocken, PA: ASTM.
Bisby, L. A., and V. K. Kodur. 2007. “Evaluating the fire endurance of concrete slabs reinforced with FRP bars: Considerations for a holistic approach.” Composites Part B 38 (5): 547–558. https://doi.org/10.1016/j.compositesb.2006.07.013.
CSA (Canadian Standards Association). 2010. Specification for fibre-reinforced polymers. CSA S807. Mississauga, ON, Canada: CSA.
CSA (Canadian Standards Association). 2012. Design and construction of building components with fibre-reinforced polymers. CSA S806. Mississauga, ON, Canada: CSA.
CSA (Canadian Standards Association). 2015. Concrete materials and methods of concrete construction/test methods and standard practices for concrete. CSA A23.1-14/A23.2-14. Mississauga, ON, Canada: CSA.
Gao, W., J.-G. Dai, J. Teng, and G. Chen. 2013. “Finite element modeling of reinforced concrete beams exposed to fire.” Eng. Struct. 52: 488–501. https://doi.org/10.1016/j.engstruct.2013.03.017.
Hajiloo, H., and M. 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, and J. Gales. 2018. “Mechanical properties of GFRP reinforcing bars at high temperatures.” Constr. Build. Mater. 162: 142–154. https://doi.org/10.1016/j.conbuildmat.2017.12.025.
Hajiloo, H., M. F. Green, M. Noël, N. Bénichou, and M. Sultan. 2017. “Fire tests on full-scale FRP reinforced concrete slabs.” Compos. Struct. 179: 705–719. https://doi.org/10.1016/j.compstruct.2017.07.060.
ISIS (Intelligent Sensing for Innovative Structures) Canada. 2007. Reinforcing concrete structures with fibre reinforced polymers. Design Manual 3. Winnipeg, MB, Canada: ISIS Canada.
Kumahara, S., Y. Masuda, H. Tanano, and A. Shimizu. 1993. “Tensile strength of continuous fiber bar under high temperature.” ACI Spec. Publ. 138: 731–742.
Masmoudi, R., A. Zaidi, and P. Gérard. 2005. “Transverse thermal expansion of FRP bars embedded in concrete.” J. Compos. Constr. 9 (5): 377–387. https://doi.org/10.1061/(ASCE)1090-0268(2005)9:5(377).
Nigro, E., G. Cefarelli, A. Bilotta, G. Manfredi, and E. Cosenza. 2011a. “Fire resistance of concrete slabs reinforced with FRP bars. Part I: Experimental investigations on the mechanical behavior.” Composites Part B 42 (6): 1739–1750. https://doi.org/10.1016/j.compositesb.2011.02.025.
Nigro, E., G. Cefarelli, A. Bilotta, G. Manfredi, and E. Cosenza. 2011b. “Fire resistance of concrete slabs reinforced with FRP bars. Part II: Experimental results and numerical simulations on the thermal field.” Composites Part B 42 (6): 1751–1763. https://doi.org/10.1016/j.compositesb.2011.02.026.
Underwriters’ Laboratories of Canada. 2007. Standard methods of fire endurance tests of building construction and materials. CAN/ULC-S101-07. Toronto, ON, Canada: Underwriters’ Laboratories of Canada.
Weber, A. 2008. “Fire-resistance tests on composite rebars.” In Proc., Int. Conf. on FRP Composites in Civil Engineering (CICE2008). Zurich, Switzerland: EMPA.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 23 • Issue 2 • April 2019
Copyright
©2019 American Society of Civil Engineers.
History
Received: Nov 21, 2017
Accepted: Oct 16, 2018
Published online: Feb 15, 2019
Published in print: Apr 1, 2019
Discussion open until: Jul 15, 2019
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.