Seismic performance and resilience of composite damping self-centering braced frame structures

A magnetorheological self-centering brace (MR–SCB) has been proposed to improve the energy dissipation capability of the brace. In this paper, a 15-story MR–SCB braced frame is numerically analyzed to examine its seismic performance and resilience. The MR–SCB provides higher lateral stiffness than the buckling restrained brace and greater energy dissipation capability than the existing self-centering brace. The brace also exhibits a reliable recentering capacity. Under rare earthquakes, the maximum average residual deformation ratio of the structure is less than the 0.5% limit. Under mega earthquakes, the maximum average interstory drift ratio of the structure does not exceed the 2.0% elastoplastic limit, and its maximum average floor acceleration ratio is 1.57. The effects of mainshock and aftershock on the structural behavior are also investigated. The interstory drift and residual deformation of the structure increase with the increase of the intensity of the aftershock. Under aftershocks with the same intensity as the mainshocks, the maximum increment of the residual deformation ratio of the structure is 81.8%, and the average interstory drift ratios of the 12^th, 7^th, and 3^rd stories of the structure are increased by 13.4%, 9.2% and 7.5%, respectively. The strong aftershock may significantly cause increased damage to the structure, and increase its collapse risk and residual deformation.