Seismic Analysis and Design of a Resilient Steel Frame with Multiple Lateral Force-Resisting Systems

Earthquake-induced damage often is caused by large deformation and floor acceleration. To ensure a fast function recovery process, controlling postevent permanent deformation also is very critical. Combining the merits of different lateral force-resisting systems is a promising solution to control these engineering demand parameters simultaneously. Therefore, this study investigated a resilient steel frame with multiple lateral force-resisting systems and developed the corresponding seismic design method. Specifically, the proposed steel frame consists of buckling-restrained braces, viscous damping braces, and a moment-resisting frame, which mainly control peak interstory drift ratio (theta p), peak floor acceleration (Ap), and residual interstory drift ratio (theta r), respectively. Based on the equivalent single-degree-of-freedom systems, nonlinear time-history analyses were conducted to obtain various constant-ductility response spectra. These response spectra were incorporated into the proposed design method which jointly defines theta p, Ap, and theta r as the performance objectives. A six-story benchmark steel frame was selected for demonstrating the seismic performance of the frame and validating the design method. Because theta r is a critical metric for evaluating seismic resilience, three levels of theta r were used in the design examples. The seismic analysis results indicated that the designed structures can well satisfy the preselected performance objectives.