Influence of thermal effects on debonding response of CFRP-to-concrete/ steel interfaces under thermal and mechanical loads: An analytical solution

A major concern regarding the effective use of carbon fibre reinforced polymer (CFRP) in the strengthening of concrete/steel structures is the premature debonding of CFRP-to-concrete/steel interfaces. As temperature changes, discrepancy in the coefficients of thermal expansion (CTE) between CFRP and the substrate yields strain differentials and thermal stresses, which accelerates the interfacial debonding affecting the bonding perfor-mance. Many analytical solutions are available for the debonding behaviour of CFRP-to-concrete/steel joints under temperature changes but fail to account for arbitrary bond length and interfacial friction. This paper proposes an analytical solution for evaluating the thermal effects on the debonding response of CFRP-to-concrete/steel interfaces under mechanical and thermal loads. Closed-form expressions with interfacial fric-tion are deduced for the complete debonding process of both long and short joints. After the validity of the analytical solution is verified with four sets of experimental data, the influences of the thermal effects, CFRP thickness, and CFRP elastic modulus are quantitatively evaluated. The results show that the proposed solution is effective in evaluating the debonding response of CFRP-to-concrete/steel joints under thermal and mechanical loads. The thermal effects are strongly associated with the bond length and become more significant when using thicker and stiffer CFRP materials for strengthening applications.