A simple 1D-Finite Element approach for the study of the bond behavior of masonry elements strengthened by FRP

The paper presents a simple approach to simulate the bond behavior of masonry elements externally strengthened by FRP-systems. The approach is based on a 1D-Finite Element discrete model where a simple non-linear constitutive law is introduced to model the behavior of the interface layer placed between the FRP-strengthening and the masonry substrate. The reliability and the potentialities of the approach are assessed in the paper by comparing the results of the numerical analyses with the experimental outcomes of two case studies available in the current literature. Although the simplicity of the proposed approach, both in the modeling phase and in the derivation of the parameters, its application provides a good agreement with the experimental results in terms of the global carrying capacity and, also, the local response of the strengthened system. In addition, in the case of unit-mortar assemblages, the approach is able to model the specific aspects of the bond behavior of FRP-strengthened systems dependent on the presence of mortar joints. The paper also shows the potentiality of the proposed approach in deriving the main parameters characterizing the bond behavior of FRP-strengthened masonry specimens which are generally accounted in theoretical models and in the design formulas contained in the current standard codes.