Seismic performance of an assembled self-centering buckling-restrained brace and its application in arch bridge structures

Aiming to reduce residual deformation, herein, we propose the design concept of a self-centering buckling -restrained brace (SC-BRB) applied to the structural fuse of arch bridge structures. First, a novel assembled SC-BRB with combined disc springs is proposed. Notably, the hysteretic curve characteristics can be effectively controlled by the ratio of the BRB system load capacity to the SC system preload. The construction and operating mechanism of the novel SC-BRB are described, and a theoretical hysteretic model under cyclic loading is derived. Five SC-BRB specimens with different combinations are designed and fabricated. Through quasi-static tests, the characteristics including residual deformation and hysteretic energy dissipation are analyzed and compared to explore the self-centering effect and damage mode. The test results reveal that the hysteresis curve of the assembled SC-BRB is characterized by an apparent flag-type form and stable hysteretic performance. The com-bined disc spring significantly reduces the residual deformation of the brace, resulting in an apparent self -centering effect. The theoretical hysteretic model proposed in this paper agrees well with the test results. Finally, a comparative analysis is conducted on the seismic performance of a concrete filled steel-tube (CFST) arch bridge structure with three types of lateral braces: SC-BRB, BRB, and an ordinary brace. The OpenSees analysis results demonstrate that the CFST with the SC-BRB demonstrates better performance in terms of the displacement response and residual deformation compared with the other two CFSTs.