Approximate Evaluation of Maximum Force Transferable at FRP-Masonry Interface

The debonding phenomenon between fiber-reinforced polymer (FRP) composites and masonry is influenced by the presence of mortar joints that could reduce the bond capacity of the FRP-brick interface (i.e., in the absence of the joints). The actual estimate of the maximum load transferable at the FRP-masonry interface is cumbersome. Thus, the aim of this paper is twofold. First, the paper provides a set of useful key remarks to understand how the presence of joints influence the behavior of the FRP-masonry interface with respect to the FRP-brick interface. This is an important aspect of the paper because it summarizes previous work and provides guidance for designers and researchers. Secondly, this paper proposes a step-by-step procedure to obtain an approximate estimate of the maximum transferable load at the FRP-masonry interface provided that the characteristics of the FRP-brick and FRP-mortar interfaces are known or can be derived from codes and guidelines, and the thickness of brick and joints is assigned. To the best knowledge of the authors, an approximate formulation for the FRP-masonry interface is presented in this paper for the first time together with guidance to evaluate when an approximate formulation might be necessary based on the desired acceptable error. The comparison between the maximum load transferable at the FRP-masonry interface and its approximation presented in this paper provides a relative error of roughly 0.4% for case of practical interest. Finally, the paper provides an example application of the proposed procedure.