Bond stress-slip relationship of CFRP bar-concrete interface of CFRP reinforced concrete subjected to reversed cyclic loading

Focuses on the seismic performance of carbon fiber-reinforced polymer (CFRP) reinforced concrete members wherein the bonding characteristics between the CFRP bars and concrete play an essential role, this paper focuses on deriving simplified formulas of the bond stress-slip relationship by a mesoscopic numerical approach. All mesoscopic factors that influence remarkably the bond properties are considered. Influences of rebar diameters, rib heights, rib width-to-spacing ratios, rib spacings, embedment lengths and concrete strengths on the bond resistance and the residual bond stress are analyzed. Based on the numerical results, explicit formula of the bond stress on the interface between the CFRP bars and the concrete is written as a function of the above-mentioned mesoscopic factors. Interestingly, it is found that all formulas can be rewritten into a uniform form. Predictions of the bond stress by the proposed formulas show good consistencies with experimental results, and the proposed formulas allow a full understanding of the related debonding mechanism for the CFRP bar-concrete interface of CFRP reinforced concrete undergoing reversed cyclic loading.