Experimental and numerical study of a novel double-stage capacity-adjustable buckling-restrained brace

To enhance the seismic performance of buckling-restrained braces (BRBs) and meet the requirements for seismic resilience under multi-level earthquakes, this study proposes a novel double-stage capacity-adjustable buckling-restrained brace (CABRB). The CABRB features a sacrificial component and an energy-dissipating BRB working in parallel. During small earthquakes, the sacrificial component provides additional stiffness and strength to ensure structural serviceability. As seismic intensity increases, the sacrificial component fails, helping to concentrate the seismic damage on the BRB component and protecting other structural components. This study first designed and conducted quasi-static tests to evaluate the seismic performance and post-earthquake reparability of the CABRB equipped with various opening-shaped sacrificial plates. Upon the experimental investigations, refined finite element models were established to conduct parametric analyses for evaluating the influences of geometric parameters of the sacrificial plate on the mechanical properties of the CABRB. Additionally, two-story braced frame numerical models, one equipped with BRBs and the other with CABRBs, were established and compared to validate the feasibility and applicability of the CABRBs. The results indicate that the proposed CABRB, with its unique double-stage mechanical behavior, not only meets the multi-level seismic performance requirements, but also exhibits excellent post-earthquake reparability. This provides valuable insights and technical support for the multi-level seismic design of civil structures.