Numerical Investigation on the Efficiency of Self-Centering Two-Yield Buckling Restrained Brace on Low-Rise Steel Frames

This study presents a novel self-centering two-yield buckling-restrained brace (SC-TYB) incorporating a dual-core configuration with distinct yield strengths, utilizing low-yield point and high-strength steel. This system is introduced to mitigate a critical limitation inherent in buckling-restrained braces (BRB), which rely on hysteretic behavior for seismic energy dissipation and experience a significant reduction in post-yielding stiffness. The feasibility and performance of the proposed brace in braced frames are assessed through a simplified core-spring finite element model. Through nonlinear analysis, this study evaluates the behavior of two-story SC-TYB frames with multiple prevalent arrangements. Pushover and time history analysis utilizing near-field and far-field earthquake records were performed to investigate the ductility, over strength, response modification factors, and the seismic response of braced frames, focusing on maximum inter-story drifts and residual drifts. The results demonstrate that the proposed BRB exhibits a multistage yield pattern and maintains significant post-yield stiffness, effectively counteracting P-delta effects. Also, the response modification factor of frames with the introduced SC-TYB was obtained on average 40% higher than that of BRB frames. Meanwhile, in comparison, the analysis reveals a 10% and 35% average decrease in inter-story and residual drifts, respectively, for SC-TYB frames. Finally, the diagonal arrangement of the proposed system exhibits the minimum inter-story and residual drifts among the evaluated models.