Seismic collapse assessment of hybrid self-centering piston-based braced frames equipped with SMA bars and friction springs

Abstract

Hybrid Self-centering Piston-Based Bracing (SC-PBB) is a cutting-edge, resilient earthquake-resistant element that comprises friction springs (FSs) and super-elastic shape memory alloy (SMA) bars. This innovative bracing component is specifically devised to attain a full self-centering response under a design-level earthquake, effectively mitigating the need for post-earthquake repairs and downtime. Nevertheless, concerns surrounding the potential collapse of Self-centering Piston Based Braced Frames (SC-PBBFs) during severe seismic motion have highlighted the necessity for a comprehensive collapse assessment. This paper evaluates the seismic collapse of SC-PBBFs by utilizing the FEMA P695 methodology. A set of buildings ranging from low- to high-rise archetypes is designed with a proposed response modification coefficient of R = 8. Incremental dynamic analyses (IDA) are conducted under 44 far-field ground motions to evaluate Adjusted Collapse Margin Ratios (ACMRs). Additionally, the collapse risk of the archetypes is measured under the influence of system-level uncertainty. The outcomes indicate that the proposed design procedure ensures an adequate margin of safety against collapse for SC-PBBFs.