ABSTRACT
In recent years, the strengthening of masonry structures with external bonded (EB) fiber reinforced polymers (FRPs) has been increased to improve the strength and ductility of walls under seismic actions. The presence of FRP elements strongly affects the structural response through complex interaction mechanisms between masonry and strengthening elements. Many aspects of this strengthening method are not yet completely known; in particular, the debonding mechanisms of FRP strips need to be analyzed through more investigation. In this paper, an iterative, incremental non linear three dimensional Finite Element (FE) model is developed to analyze the response of historic masonry wall, with and without strengthening by Glass-FRP strips, under in-plane cyclic loading, addressing particular regard to the delamination phenomenon. A numerical macroscopic model obtained from the combination of constitutive laws is adopted to simulate the behaviour of the unreinforced and reinforced masonry. Both progressive local failure and nonlinear stress-strain relationship of masonry are taken into account. For the GFRP strips, a model that considers the reinforcement perfectly glued to the masonry support has been used. Finally, the developed analytical model is calibrated and validated by comparison with experimental results and interesting aspects are remarked.
