In-plane seismic performance of open masonry walls retrofitted with steel-bar truss units

•An experiment was conducted to evaluate the in-plane seismic performance of an opened masonry wall strengthened by external prestressed steel-bar truss unit with varying levels of prestressing forces and two sizes of an opening.•The test results show how the presented retrofitting method is effective for improving the seismic performance of an opened masonry wall.•The retrofitting method made weak wall piers into strong wall piers, and the behavior of the opened masonry wall acts as moderate coupled wall. In this experimental study, the in-plane seismic performance of masonry walls with openings that were incorporated with external prestressed truss units was evaluated based on cyclic loading tests. The external prestressed truss units comprised two vertical, two diagonal, and two horizontal members. In addition, prestressing force was applied to the vertical members. Each unreinforced masonry wall (URM) exhibited an open window or an open door. Meanwhile, the reinforced masonry wall comprised four external prestressed truss units, which were installed on the front and back of the wall-piers on both sides of the opening. The peak strength of the reinforced masonry wall with window opening increased by 146%–153% compared with that of the URM. Furthermore, the peak strength of the reinforced masonry wall with door opening increased by 120%–144% compared with that of the URM. Moreover, the energy dissipation capacity of reinforced specimens increased more compared with that of URM. However, the proposed reinforcement technique does not increase the overall displacement capacity as all the specimens at the same target drift ratio ended up with a stability problem. In addition, the strengthening method did not improve the effective stiffness and ductility of the reinforced masonry wall, and they were lower than that of the URM. The masonry walls reinforced with external prestressed truss units exhibited behavior similar to those of a moderate coupled wall. As there was no retrofitting unit in the upper beam of the opening, shear failure occurred at the interface between the wall piers and upper beam.