Experimental study on interfacial behavior of CFRP-bonded concrete

External bonding of Carbon Fiber Reinforced Plastic (CFRP) sheets has come to be regarded as a very effective method for the strengthening of reinforced concrete structures. The behavior of CFRP-strengthened RC structures is mainly governed by the interfacial behavior, which represents the stress transfer and relative slip between concrete and the CFRP sheet. In this paper, the effects of bonded length, width, and concrete strength on the interfacial behavior are experimentally verified and a bond-slip model is proposed based on the experimental results. From the pull test for CFRP-bonded concrete, it is found that the bond strength increases as the bond width increases and the effect of concrete strength is minor. The proposed bond-slip model has nonlinear ascending regions and exponential descending regions, facilitated by modifying the conventional bilinear bond-slip model. Finite element analysis results of interface element implemented with bond-slip model have shown good agreement with the experimental results performed in this study. It is found that the failure load and strain distribution predicted by finite element analysis with the proposed bond-slip are in good agreement with results of experiments.