An analytical method to estimate the resisting bending moment of FRCM strengthened masonry walls subjected to out-of-plane load

A large number of existing masonry structures are in need of strengthening and retrofitting. A possible alternative to traditional strengthening techniques is represented by the use of externally bonded fiber reinforced composites. Between them, fiber reinforced cementitious matrix (FRCM) composites, which are comprised of high strength fiber open meshes embedded within inorganic matrices, represent a promising solution to strengthen existing masonry structures. Although FRCM composites were shown to be effective in strengthening unreinforced masonry (URM) walls subjected to shear (in-plane load), bending (out-of-plane load), and predominant axial load, the only design guideline available is the American ACI 549.4R-13. In this paper, an analytical procedure to compute the resisting bending moment of URM walls strengthened with FRCM composites against out-of-plane load is proposed. The analytical procedure is based on simple equilibrium conditions and takes into account the characteristics of the masonry support and of the FRCM strengthening. The accuracy of the proposed procedure is assessed by comparison between the experimental results of 49 FRCM out-of-plane strengthened masonry walls collected from the literature and the corresponding analytical provisions. In addition, the experimental database collected is employed to assess the accuracy of the analytical approach provided by the ACI 549.4R-13.