Rational Approach for Evaluating Fire Resistance of FRP-Strengthened Concrete Beams
Publication: Journal of Composites for Construction
Volume 20, Issue 6
Abstract
This paper presents a rational approach for evaluating the fire resistance of reinforced concrete (RC) beams strengthened with different types of fiber-reinforced polymers (FRP). This approach is based on conventional fire design principles for RC beams, but incorporates the contribution of FRP and fire insulation in fire resistance calculations. Simplified equations are proposed for evaluating cross-sectional temperatures in fire-exposed FRP-strengthened RC beams with and without fire insulation. These temperatures are used to determine the loss of strength in steel, FRP, and concrete using temperature-dependent strength properties. Employing the strength in different materials, the moment capacity of FRP-strengthened beams is calculated, at any given fire exposure time, by applying force equilibrium and strain compatibility principles. At each time step, the limit state is applied to define the failure of an FRP-strengthened RC beam, and the time to failure is taken as the fire resistance of the beam. The validity of the proposed approach is established by comparing predicted fire response parameters with those obtained from fire resistance tests and detailed finite-element analyses. Further, the applicability of the proposed approach in practical situations is illustrated through a design example. Results from the proposed approach clearly indicate that a typical FRP-strengthened beam without supplemental fire insulation experiences a significant loss of moment capacity after approximately 20 min into fire exposure. However, a similar FRP-strengthened beam with supplemental fire insulation retains much of its moment capacity until 2 h into fire exposure.
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Acknowledgments
This material is based on work supported by the National Science Foundation under Grant No. CMMI-0855820. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the sponsors.
References
ACI (American Concrete Institute). (2008). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.” ACI 440.2R-08, Farmington Hills, MI.
Ahmed, A., and Kodur, V. K. R. (2011). “The experimental behavior of FRP-strengthened RC beams subjected to design fire exposure.” Eng. Struct., 33(7), 2201–2211.
ASCE. (2010). “Minimum design loads for buildings and other structures.” ASCE 7, Reston, VA.
ASTM. (2012). “Standard test methods for fire tests of building construction and materials.” ASTM E119, West Conshohocken, PA.
Bisby, L. A. (2003). “Fire behaviour of fibre-reinforced polymer (FRP) reinforced or confined concrete.” Ph.D. thesis, Queen’s Univ., Kingston, Canada.
Bisby, L. A., Green, M. F., and Kodur, V. K. R. (2005). “Response to fire of concrete structures that incorporate FRP.” Prog. Struct. Eng. Mater., 7(3), 136–149.
Blontrock, H., Taerwe, L., and Vandevelde, P. (2000). “Fire tests on concrete beams strengthened with fiber composite laminates.” Proc., Int. Ph.D. Symp. in Civil Engineering, Institute of Structural Engineering, Univ. of Agricultural Sciences, Vienna, Austria, 151–161.
Bruggeling, A. S. G. (1992). “External prestressing—A state of the art.”, Detroit, 61–82.
CEN (European Committee for Standardization). (2004). “Design of concrete structures. Part 1-2: General rules–Structural fire design.” EN 1992-1-2, Brussels, Belgium.
Dwaikat, M. M. S., and Kodur, V. K. R. (2013). “A simplified approach for predicting temperatures in fire exposed steel members.” Fire Saf. J., 55(1), 87–96.
FIB (Fédération Internationale du Béton). (2007). “FRP reinforcement in RC structures.”, Lausanne, Switzerland.
Firmo, J. P., Correia, J. R., and Franca, P. (2012). “Fire behaviour of reinforced concrete beams strengthened with CFRP laminates: Protection systems with insulation of the anchorage zones.” Compos. Part B, 43(3), 1545–1556.
ISO (International Organization for Standardization). (2012). “Fire resistance tests—Elements of building construction.” ISO 834, Geneva.
Kodur, V. K. R., and Yu, B. (2013). “Evaluating the fire response of concrete beams strengthened with near-surface-mounted FRP reinforcement.” J. Compos. Constr., 517–529.
Kodur, V. K. R., Yu, B., and Dwaikat, M. M. S. (2013). “A simplified approach for predicting temperature in reinforced concrete members exposed to standard fire.” Fire Saf. J., 56, 39–51.
Lie, T. T. (1992). Structural fire protection, ASCE, New York.
Palmieri, A., Matthys, S., and Taerwe, L. (2012). “Experimental investigation on fire endurance of insulated concrete beams strengthened with near surface mounted FRP bar reinforcement.” Compos. Part B, 43(3), 885–895.
Rafi, M. M., Nadjai, A., and Ali, F. (2007). “Fire resistance of carbon FRP reinforced concrete beams.” Mag. Concr. Res., 59(4), 245–255.
Wang, Y. C., Wong, P. M. H., and Kodur, V. (2007). “An experimental study of the mechanical properties of fiber reinforced polymer (FRP) and steel reinforcing bars at elevated temperatures.” Compos. Struct., 80(1), 131–140.
Williams, B., Kodur, V. K. R., Green, M. F., and Bisby, L. A. (2008). “Fire endurance of fiber-reinforced polymer strengthened concrete T-beams.” ACI Struct. J., 105(1), 60–67.
Yu, B. (2013). “Fire response of reinforced concrete beams strengthened with near-surface mounted FRP reinforcement.” Ph.D. thesis, Michigan State Univ., East Lansing, MI.
Yu, B., and Kodur, V. K. R. (2014a). “Effect of temperature on strength and stiffness properties of near-surface mounted FRP reinforcement.” Compos. Part B, 58, 510–517.
Yu, B., and Kodur, V. K. R. (2014b). “Fire behavior of concrete T-beams strengthened with near-surface mounted FRP reinforcement.” Eng. Struct., 80, 350–361.
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© 2016 American Society of Civil Engineers.
History
Received: Oct 16, 2015
Accepted: Feb 4, 2016
Published online: Apr 13, 2016
Discussion open until: Sep 13, 2016
Published in print: Dec 1, 2016
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