Development and validation analysis of a steel-lead hybrid dual-yield BRB for multi-stage seismic energy dissipation

Abstract

To address the limitations inherent in conventional all-steel buckling restrained braces (BRBs) that maintain elastic behavior and lack seismic energy dissipation during frequent earthquakes (FEs), this study proposes a novel approach of combining lead dampers with BRB, forming the development of steel-lead hybrid dual-yield BRB (or simply dual-yield BRB). Integrating lead material into the dual-yield BRB harnesses its dynamic recrystallization capacity, allowing the lead dampers to yield and efficiently dissipate seismic energy during FEs via well-designed configurations. This study delineates the approach for connecting lead dampers to BRBs and performs comparative quasi-static tests on dual-yield BRBs and conventional BRBs. Key observations from the laboratory tests confirmed that lead dampers experience earlier failure compared to inner cores. Dual-yield BRB exhibited significantly lower initial displacement requirements for energy dissipation than conventional BRB, demonstrating a hexagonal hysteretic curve, trilinear behavior in the skeleton curve, and superior overall energy dissipation capacity at small displacements. The feasible strategy of refined numerical simulations was initially validated based on experimental results. Subsequently, to enhance analysis efficiency, simplified models using truss elements were developed and endorsed. Elasto-plastic time history analyses were performed on benchmark models of 9-story steel frames, considering scenarios with no bracing, conventional BRBs, and dual-yield BRBs, exposed to FEs and maximum considered earthquakes (MCEs). Various parameters, including component forces, structural displacement and damping underwent thorough examination. These findings underscore the exceptional seismic performance and energy dissipation abilities of dual-yield BRBs, solidifying them as a valuable addition to earthquake-resistant structural systems.