Seismic performance assessment of existing low-ductility reinforced concrete double-column bridge piers retrofitted with buckling-restrained braces

Abstract

In this study, buckling-restrained braces (BRBs) are utilized to improve the seismic performance of existing reinforced concrete (RC) double-column bridge piers. 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 BRBs effectively controlled seismic damage; compared to RC-Pier, RC-Pier-BRB demonstrated a 44.8 % reduction in the 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 the peak strengths of RC-Pier and RC-Pier-BRB between 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 useable after the BRB buckled and fractured, suggesting a reliable technology for the replacement and recovery of the BRB after an earthquake.