Bond behaviors of FRP-to-concrete interface under the control of a novel end-anchorage system

The externally bonded fiber-reinforced polymer (FRP) is one of the most effective techniques for the strengthening and rehabilitation of deteriorated concrete structures. The debonding of an FRP-concrete interface is the typical failure mode of an FRP-strengthened concrete structure, leading to a very low effective utilization of FRP material and an inductile failure of the structure. In this paper, a novel end-anchorage device was developed and installed at both ends of the FRP to restrict the premature debonding of the FRP. The end-anchorage device has a ductile behavior and by relying on the deformation of the device, the deformability of the strengthened structure and the maximum FRP stress during debonding can be improved to a large extent, thus a significant improvement on the structural load capacity and ductility can be realized. In this study, the adjusting mechanism of the end-anchorage system on the bond behavior of the FRP-concrete interface was systematically investigated. First, the bond behavior of the FRP-concrete interface was experimentally studied using single shear test. Second, the bond strength, bond-slip relation curve, and the strain distribution of the FRP along the bonded area were analyzed. Finally, a prediction model for the interfacial bond strength under the end-anchorage system was proposed. Comparisons with the experimental results indicate that the proposed model can provide a reasonable good accuracy in predictions.