Effect of High Temperature on Bond Strength of FRP Rebars

Abstract

The bond properties of fiber reinforced polymer (FRP) reinforcing bars (rebars) at temperatures ranging from room temperature (20°C) to high temperatures of up to 250°C are discussed in this paper. The bond properties in this temperature range were studied for a number of commercially produced rebars, where different bond “treatments” were applied to FRP rebars. Test results showed a reduction of between 80 and 90% in the bond strength as the temperature increased from 20 to 250°C. In comparison, ordinary deformed steel rebars showed a reduction of only 38% in the same temperature range. In addition, a reduction in the bond stiffness, which was determined from the slope of the ascending branch of the pullout load versus slip curve, was seen as the temperature increased. At elevated temperatures the postpeak bond decrease was gradual as compared with the instantaneous drop at room temperature. Greater sensitivity to high temperatures was seen in FRP rebars, in which the bond relies mainly on the polymer treatment at the surface of the rod.