Closure to “Evaluation of Fire Endurance of Concrete Slabs Reinforced with Fiber-Reinforced Polymer Bars” by V. K. R. Kodur and L. A. Bisby

Abstract

This closure offers the rebuttal of the original authors (Kodur and Bisby, 2005) of a study undertaken to assess and develop information on the fire endurance of fiber-reinforced polymer (FRP) reinforced concrete structural members. Their research results showed that FRP-reinforced concrete slabs have lower fire resistance than slabs reinforced with conventional reinforcing steel when fire endurance is defined in terms of the critical temperature of the reinforcement. The authors respond to a commentary (Gamble, 2006) in which the discusser addresses the unresolved question about the bond strength of FRP reinforcement, noting that tests of FRP-RC slabs (and beams) thus far have been insufficient. In connection with such tests, a search should be made for polymer matrix materials with the best and worst response to temperature. A final comment was provided on the surface roughness necessary for bond; some approaches may be more vulnerable to the effects of heat than others. The researchers reply to each of these concerns in turn, predominantly agreeing with the discusser's arguments. However, they caution that some situations may not require additional cost and effort to establish materials with fire endurance. For example, when FRP bars are used as slab reinforcement in bridge decks, the additional cost and effort of developing and using a thermally resistant polymer matrix may be neither justified nor necessary. They conclude that bond is clearly a factor that should not be overlooked in assigning fire ratings to FRP-reinforced slabs.