FEM analysis of bonding defects in FRP external reinforcements of RC elements

External FRP reinforcements have widely become one of the most effective and frequently practiced solutions for refurbishment and strengthening of existing structures, especially in the field of RC structures. The overall design approach is commonly based on the assumption of perfect bonding between the reinforcement and the substrate, granted by glues like epoxy resins, so that the prevention of a premature debonding is a crucial issue. National standards and guidelines for FRP reinforcements design usually don't specify to what extent an FRP application can be regarded as satisfactory with respect to bonding lacks and defects, while several researches, devoted to defects detection by means of Non Destructive Techniques, have proved that a flawless bonding can hardly be granted, especially while using epoxy resins. The present paper is aimed to investigate the effects of these imperfect bonding on the reinforcement performance, in terms of number and overall surface of defects, by means of numerical models.