Numerical and experimental study of GFRP-masonry interface behavior: Bond evolution and role of the mortar layers

Bond behavior between masonry and FRP was investigated in the present paper; in particular, its numerical modeling was carried out considering both single bricks and masonry prisms (with presence of mortar joints between the bricks) as possible substrate. The numerical approach was presented and results compared with those obtained from a recent extensive experimental campaign carried out on GFRP sheets bonded to bricks and prisms, and by considering four different types of clay bricks. Was presented an investigation of the role of the non-linear behavior of the substrate on the bond behavior when using an interface law, and a deep analysis of the debonding process leading to the observation of two different interface mechanisms, properly captured by introducing two separate interface laws and their effectiveness discussed in terms of force-elongation curves or strain, shear stress distributions along the bonded part. Numerical results showed that the adopted interface model is in good agreement with the experimental results. Moreover, the effect of discontinuity represented by the presence of weak mortar layers between bricks (inside prisms) was discussed and clarified.