Shaking table tests of masonry wall reinforced with steel-bar truss units linked by spring dampers

Abstract

Since unreinforced masonry buildings are vulnerable to earthquakes, various studies have been conducted to improve their seismic performance. In this study, spring dampers were added to steel-bar truss units to improve the performance of the reinforcement method, and shaking table tests were performed to evaluate their seismic performance. Furthermore, a full-scale I-shaped masonry wall was prepared by considering the inner walls of masonry buildings, and steel-bar truss units linked by spring dampers were installed on both sides of the specimen. For the unreinforced specimen, the horizontal spectral acceleration calculated for the flexible components was 0.54 g, the seismic loading level was sequentially increased by 20%, and in-plane excitation was performed. The experimental results showed that the unreinforced masonry specimen resisted up to 220% of the designed seismic acceleration, whereas the reinforced masonry specimen resisted up to 320%. At the end of the experiment with the unreinforced masonry specimen, the response peak acceleration and drift ratio of the reinforced specimen were approximately 36% and 50% lower than those of the unreinforced masonry specimen, respectively. This implies that the diagonal bars constituting the truss units reduced the story drift ratio by suppressing shear deformation, and the vertical bars prevented cracking by introducing an additional axial force on the masonry wall. The experimental results demonstrated that the reinforcement method efficiently improved the seismic performance of the masonry wall in terms of stiffness, ductility, shear force. Because this study was conducted with only one variable, i.e., the presence/absence of the strength method, further research with various variables such as a number of steel-bar truss units, prestressing force level, spring stiffness of spring damper is required to verify the practical applicability of the method.