Development of bond strength model for CFRP-to-concrete joints at high temperatures

Because of temperature sensitivity of the adhesives used in the interface, temperature variations may significantly affect the bond behavior of carbon fiber reinforced polymer (CFRP) to concrete joints. An analytical solution is used in this work to derive the two-parameter bond-slip relationship of CFRP to concrete bonded joints at high temperatures. The values of the key parameters at elevated temperatures can be directly calculated from the expressions for the strength and the stiffness of CFRP to concrete joints. Considering the effect of the free end slip on the bond behavior, a simplified formula of the peak load for a given joint is presented. Based on regression analyses of existing test data, it is found that the normalized value of interfacial bond property at elevated temperatures should be a function of ΔT (service temperature subtracts glass transition temperature). The proposed bond strength-temperature model here represents the test data well, despite the large scatter.