Discussion of "evaluation of fire endurance of concrete slabs reinforced with fiber-reinforced polymer bars" by V. K. R. Kodur and L. A. Bisby

This brief discussion article comments on a study (Kodur and Bisby, 2005) undertaken to assess and develop information on the fire endurance of fiber-reinforced polymer (FRP) reinforced concrete structural members. The 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 researchers conclude that a higher fire resistance for FRP-reinforced concrete (RC) slabs can be obtained through greater concrete cover thickness and through the use of carbonate aggregate concrete. The commentary author 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 is provided on the surface roughness necessary for bond; some approaches may be more vulnerable to the effects of heat than others.