Abstract
Beam-through tension-only concentrically braced frame (denoted as BTF) is being gradually accepted in building industries due to its rapid prefabrication and higher economic benefits. However, due to the limited energy dissipation capacity and high pinching hysteretic behavior of tension-only braces, the BTF buildings may be vulnerable to soft-story failure under rare seismic events. Here, an Energy-absorbing Rocking Core (ERC) is being proposed to mitigate the soft-story failure mechanism and improve the energy absorption capacity of BTF. The ERC consists of a pin-supported stiff Rocking Core (RC) with either two friction spring dampers (FSDs) or two buckling-restrained braces (BRBs). The rocking core's large stiffness and strength could develop a uniform distribution of inter-story drift in the structural system. The two FSDs or BRBs are adopted to improve the energy-absorption capacity of the BTFs. In addition, the FSDs can also aid in eliminating the residual drift of the structural system with its superior self-centering capacity. First, Nonlinear Dynamic Analyses (NDA) on two benchmark BTFs were conducted with twenty-one earthquake records to investigate the validity of ERC in enhancing the seismic performance of BTF. Then, the influence of key design factors, including the stiffness of ERC to BTF, the post-yield stiffness of FSD, and the stiffness of RC on the seismic performance of BTFs was studied through a systematic parametric study using NDA. Results indicate that the ERC can significantly enhance the seismic performance of BTFs and control the maximum residual inter-story drift within 0.5%. Some critical design issues related to the implementation of ERC in the BTFs are also presented.