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 (θp), peak floor acceleration (Ap), and residual interstory drift ratio (θr), 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 θp, Ap, and θr 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 θr is a critical metric for evaluating seismic resilience, three levels of θr were used in the design examples. The seismic analysis results indicated that the designed structures can well satisfy the preselected performance objectives.