Mitigation of residual deformations in steel braced frames through an innovative Y-shaped hybrid buckling restrained braces

Abstract

This investigation introduces a novel all-steel Y-shaped HBRB (YHBRB) incorporating three cores with varying yield strengths to enhance the seismic resilience of these brace types. The mechanical properties of the YHBRB were derived theoretically. Then, a numerical investigation was undertaken to elucidate the factors influencing its hysteretic behavior, encompassing hysteresis curves, backbone curves, stiffness degradation, cumulative energy dissipation, equivalent damping ratio, self-centering capacity, and other pertinent mechanical indices, through the application of finite element analysis. To detect the optimal core material combination for YHBRB, a parametric study was conducted on various high-performance materials, considering their impact on the cyclic behavior of the YHBRB. In the second phase of this investigation, a comparative analysis was conducted to evaluate the efficacy of the proposed YHBRB design methodology. Four prototypical braced frame configurations, each incorporating YHBRBs, were subjected to numerical simulations. These models were compared against conventional buckling-restrained braced (BRB) frames and hybrid BRB (HBRB) frames to facilitate a comprehensive assessment. Nonlinear dynamic analyses were executed under four distinct seismic hazard levels to quantify the seismic performance of these structures. The results demonstrate that YHBRB frames exhibit superior performance. YHBRB frames show a substantial reduction in residual drift compared to HBRB frames, especially BRB frames, in damage mitigation.