Seismic Design and Performance Evaluation of Self-Centering Hybrid Rocking Braced Steel Frames

An innovative self-centering hybrid rocking braced steel frame (SCHRBF) with separate braced span and rocking span is proposed for improving seismic resilience. The braced span utilizes buckling-restrained braces (BRBs) to provide energy-dissipating capacity, and the rocking span consists of stiff rocking cores and self-centering braces (SCBs) to achieve a uniform inter-story drift distribution and low post-earthquake residual displacement under a strong earthquake. This study first describes the basic composition and nonlinear mechanical behavior of this novel system. Then, a force-based seismic design procedure for the SCHRBF system is proposed, including the determination and allocation of base shear, design of BRBs in braced span, design of SCBs in rocking span, and design of rocking core members. The influence of key design parameters on the seismic responses of the system is then explored through parametric analysis. And recommended values of the design parameters are provided according to the analysis results. Although the properly designed structure has significant partial re-centering behavior, its peak inter-story drifts, residual inter-story drifts, and deformation patterns can be effectively controlled under strong earthquakes. Finally, the superiority of the SCHRBF in controlling seismic displacement responses is verified by comparing with other structural systems.