Analytical study of FRP debonding in a real-scale concrete strengthened beam

The exploitation of the mechanical properties of fiber-reinforced polymers (FRP) externally bonded to concrete members is limited by the occurrence of debonding. Single- and double-lap shear tests were performed to study the debonding process. However, the results of these tests fail to describe the debonding process when multiple substrate cracks occur, as in the case of reinforced concrete beams strengthened in flexure. In this paper, an analytical model is proposed to describe the load response of a concrete beam strengthened in flexure with an externally bonded FRP composite. The profiles of the FRP-concrete slip, FRP axial force, and cross-section rotation, the evolution of the cracking process, and the failure mode may be obtained by this model. The results of the model shed light on the debonding process in FRP-strengthened beams and may be used to investigate the relationship between the bond capacity of FRP-concrete interfaces with a single crack and that observed in real-scale strengthened beams.