A coupled interface-body nonlocal damage model for frp strengthening detachment

Aim of the paper is to propose a new coupled interface-body damage model for the study of the detachment process in concrete or masonry structures strengthened with fiber reinforced polymers (FRP). In particular, a model of the FRP-concrete or -masonry interface, accounting for the coupling between the degradation of the cohesive material and the FRP detachment, is presented. To this end, a nonlocal damage model is considered for the quasi-brittle material. Regarding the interface, a model which accounts for damage, unilateral contact and friction is developed. The novelty of the proposed model consists in taking into account the coupling between the body and the interface damage, ensuring that the interface damage is not lower than the body one. Some numerical examples and a comparison with experimental data are presented in order to verify the efficiency of the proposed model in reproducing the FRP decohesion from the support cohesive material.