A new cohesive law for the simulation of crack propagation under cyclic loadings. Application to steel- and concrete-FRP bonded interface

Abstract This paper presents a new cohesive law for the modelling of interfaces under mixed-mode cyclic loading. The formulation is based on the definition of a free energy cohesive function which governs the interface behaviour under monotonic loading, which is then extended to fatigue-driven decohesion through the introduction of a scalar damage variable, whose evolution in time is governed by a phenomenological rate equation. The cohesive model is formulated for a mixed-mode problem and then it is applied for the simulation of debonding phenomena occurring at the interface under a pure a shear stress state. Experimental results available in literature, related to single-lap shear tests, performed on both concrete and steel specimens reinforced by fibre reinforced composite (FRP), are used to validate the proposed model and to show its effectiveness to simulate very closely the observed experimental behaviour.