This study employs buckling-restrained braces (BRBs) as structural fuse components in existing reinforced concrete (RC) multi-column bridge bents with low reinforcement ratios to enhance their seismic performance and resilience. Revised theoretical equations are derived to predict the strength, stiffness, and yield displacement of existing RC multi-column bridge bents, as well as the contributions of BRBs to their seismic performance. The accuracy of the revised theoretical solutions is validated through numerical results from multi-column bridge bents with and without BRBs. Furthermore, a seismic retrofitting design method is established based on theoretical formulas and the structural fuse concept to design BRBs and define their optimal ranges, ensuring structural elasticity. The proposed design method is validated through a case study on an existing RC multi-column bridge bent with low reinforcement ratios that has been retrofitted with BRBs and subjected to E1 and E2 seismic waves. Two 1/2-scale models of RC double-column bridge piers—one retrofitted with a BRB (RC-Pier-BRB) and the other without a BRB (RC-Pier)—were designed and compared. The failure mode, stiffness, strength, energy dissipation, and curvature of RC-Pier-BRB and RC-Pier were compared through pseudo-static tests. Fiber finite element models were created using OpenSees to replicate the experimental results. The findings showed that the discrepancies between the theoretical and numerical results for yield displacement, yield strength, and equivalent elastic stiffness of RC multi-column bridge bents were 16.2%, 11.5%, and 0.3 %, respectively. Additionally, the seismic performance and resilience of existing multi-column bridge bents with a low reinforcement ratio can be enhanced by BRBs, as proposed in the design method. Nonlinear dynamic time history analyses revealed a significant reduction in the maximum displacement responses of the BRBs-retrofitted multi-column bridge bent, with decreases of 68.7 % and 74.2 % under E1 and E2 seismic waves, respectively, accompanied by corresponding reductions in maximum curvature responses of 69.9 % and 79.8 %. BRBs effectively controlled seismic damage; compared to RC-Pier, RC-Pier-BRB demonstrated a 44.8% reduction in maximum curvature. The strength of RC-Pier-BRB increased by 59.2%, and its energy-dissipation capacity grew by 18–40% after BRB retrofitting. The numerical model accurately reproduced the trends in the strength, strength degradation, seismic behavior after BRB fracture, and curvature in the plastic zone of the test models. The differences in peak strength between RC-Pier and RC-Pier-BRB in the numerical and experimental results were 3.90% and 0.43%, respectively. The errors in the maximum curvatures for RC-Pier and RC-Pier-BRB between the numerical and experimental results were 2.03% and 8.53%, respectively. Therefore, retrofitting the existing RC double-column bridge piers with BRBs can improve seismic performance and damage control. Furthermore, the connection bases and plates of the BRB remained usable after the BRB buckled and fractured, suggesting a reliable technology for replacing and recovering the BRB after an earthquake.

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