One novel block-type brace connector for retrofitting reinforced concrete frames

Abstract

Buckling-restrained braces are widely utilized for retrofitting existing reinforced concrete frames. However, conventional plate-type brace connectors and joints often suffer damage from the additional forces exerted by buckling-restrained braces during earthquakes. This paper proposes a novel block-type brace connector to address this issue. The seismic performance of this new connector is evaluated through pseudo-dynamic and quasi-static tests. Pseudo-dynamic test results indicate that the reinforced concrete frame retrofitted with the new connectors demonstrates superior seismic performance compared to the frame without retrofitting. During a rare earthquake, the maximum inter-story drift ratios are 1/308 for the frame with new connectors and 1/84 for the frame without retrofitting. Quasi-static test results show that the new connectors shift the potential plastic hinges of the beam away from the gusset plate region by moving the post-installed anchorage position outward. The gusset plate of the conventional connector buckles at an inter-story drift ratio of 1/30, while that of the new connector avoids buckling due to the restraint from the concrete block. Overall, the new connector can mitigate the adverse effects of the additional forces from buckling-restrained braces and improve the seismic performance of the existing reinforced concrete frames.