A novel hybrid strong-back system to improve the seismic performance of steel braced frames

• Published in: Journal of Building Engineering 2024-05, Vol.84, p.108482, Article 108482
• Main Authors: Soleymani, Atefeh, Saffari, Hamed
• Format: Article
• Language: English
• Subjects: Inter-storey drift; Seismic energy; Shear link; Soft-storey mechanism; Strong-back
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2024.108482

Soft-storey behavior is prevalent in steel braced frames designed and built following either current or pre-modern seismic standards. Based on past research, various rehabilitation or construction techniques have been proposed to detect underlying behavior patterns, increase ductility, reduce inter-storey drift, and achieve higher levels of performance in these frames. This paper investigates and presents numerical results for a newly introduced hybrid seismic resisting configuration using nonlinear cyclic and nonlinear time history analysis. This hybrid mechanism utilized a strong-back truss with shear links instead of the usual buckling braces in order to act as structural fuses. The strong-back part of this system utilizes a truss with strong braces that span the structure's height vertically to delay or eliminate soft-storey behavior and mobilizes all the shear links throughout the building's height. For this research, three different steel braced frames that use diverse bracing configurations were scrutinized, along with a typical strong-back system. Additionally, a new hybrid system that merges a strong-back with shear links at all levels was examined and compared to other systems. Results showed that this hybrid system can be a successful technique for preventing the soft-storey behavior. Moreover, the utilization of shear links as structural fuses in combination with strong-back frames has the potential to improve the seismic performance of conventional strong-back frames by engaging all of the links and utilizing the entire fuses' energy dissipation capacity. [Display omitted] •Determining accurate specific acceptance criteria for frames at three performance levels.•Presenting stable hysteresis curve with notable strain hardening and energy dissipation capacity.•Mobilizing all the designed structural fuses capacity into the energy dissipation.•Less normalized ISD and residual drifts for the suggested system.•Remarkable performance in preventing soft-storey mechanism due to uniform ISD profiles.