Reliability-Based Design of Force-Controlled Components in Rocking Steel-Braced Frames

Abstract

Despite the importance of force-controlled components, the implications of their failure to the overall performance of controlled rocking steel braced frames (CRSBFs) have not been examined in prior studies. This paper presents a reliability-based methodology for quantifying the relationship between the response of CRSBF force-controlled components (frame beams, columns, and braces) and system-level performance. Structural response simulation of nonlinear models was used to investigate the relationship between the behavior of CRSBF force-controlled components and system-level performance metrics. Vulnerability- and risk-based assessments of the collapse and unsafe placard trigger (UPT) limit states were performed with and without considering the possibility of force-controlled component failure, using varied ratios of the resistance to the load factors ϕ/γ used in the design of CRSBFs. The results of a case study using three-, six-, and nine-story structures showed that force-controlled component failure had a larger influence on collapse safety compared to unsafe placard assignment. For both limit states, the effect of force-controlled component behavior was lesser for taller buildings.