Experimental Evaluation of Static Cyclic In-Plane Shear Behavior of Unreinforced Masonry Walls Strengthened with NSM FRP Strips

Abstract

An experimental study was conducted to assess the effectiveness of strengthening unreinforced-masonry (URM) shear panels with near surface-mounted (NSM) fiber-reinforced polymer (FRP) strips. A total of 23 wall panels (5 URM and 18 reinforced) were subjected to vertical precompression combined with either monotonic or increasing reversing cycles of in-plane lateral displacement under fixed-fixed boundary conditions. Two wall aspect ratios (height/length) and six different reinforcement schemes were tested. The experimental program was designed to produce diagonal cracking in the URM specimens and hence investigate the effectiveness of the various reinforcement schemes in controlling this failure mode. This was achieved for the aspect ratio 1 wall panels. The study revealed that the FRP strengthening was effective in improving the ultimate load, displacement capacity, ductility, and energy dissipation compared with the URM response. For the aspect ratio 0.5 panels, base sliding failures dominated the experimental program, making it difficult to fully assess the effectiveness of the various reinforcing schemes.