A study of concrete cover separation failure in FRP-plated RC beams via an inter-element fracture approach

The phenomenon of concrete cover separation failure in FRP strengthened RC elements, unlike plate-end and mid-span debonding failure modes, has been not analyzed in depth in the literature and simplified strength models are mainly available, which possess a limited predictive capability. To this end in the present work, a novel numerical approach to investigate cover separation in FRP-plated RC beams is proposed, based on an inter-element cohesive fracture approach able to simulate multiple crack onset, propagation and coalescence in concrete structures, used in combination with an embedded truss model for taking into account the interaction between concrete cracks and tensile steel rebars. This approach has been validated by performing complete failure simulations for benchmark crack propagation examples, and subsequently has been exploited for predicting the load-carrying capacity and the related failure mode of real-scale retrofitted RC elements. Suitable comparisons with available experimental results have clearly shown the reliability and the effectiveness (in terms of numerical accuracy) of the proposed fracture approach.