In-plane shear strength models of masonry walls strengthened with steel-bar truss units

This study presented shear strength models for evaluating the seismic performance and designing masonry walls strengthened with steel-bar truss units (STUs). As an unbonded reinforcement method, STUs comprised vertical bars, diagonal bars, and horizontal bars through anchorages. The shear strength model was developed based on regression analysis using cyclic loading tests and nonlinear finite element analysis (FEA) results of reinforced masonry (RM) walls strengthened with STUs. The FEA was conducted based on the experimental data provided by Hwang et al. (2020, 2022b) and showed similar results regarding failure mode, load-displacement relationship, and shear strength. Additionally, FEA was performed for 28 unreinforced masonry (URM) walls and 44 RM walls, considering various factors such as the geometry of the masonry wall, door openings, mortar plasters, and the amount of reinforcement. The shear strength model for RM walls was developed by combining the URM walls' strength model and the presented STUs' load contribution. It was noted that the proposed shear strength models tended to overestimate rocking strength but showed similar results to the experiment for peak strength.