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

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

Qiu, Canxing / Cheng, Lizi / Du, Xiuli

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