Finite element model for FRP-from-masonry delamination: three-dimensional effects and interface traction assessment

Under the hypothesis of perfect adhesion, corroborated by the use of highly resistant glues, delamination of FRP-reinforced masonry pillars turns out to be governed exclusively by the nonlinear behavior of the quasi-brittle, heterogeneous support. However, at a structural level, delamination response can be described effectively also by concentrating all the sources of dissipation and non-linearity at the masonry-FRP interface, and assuming the support to behave elastically. In this paper, a detailed and critical comparison between two different fully three-dimensional Finite Element models is developed: the first is a model in which only the masonry is damageable whilst the FRP reinforcement adheres perfectly to the support, whereas in the second a cohesive, zero-thickness interface between the FRP and the support is considered, whilst masonry behaves as a linear elastic material. The overall response during delamination and local traction distributions at the interface are critically investigated, varying the FRP reinforcement width.