Buckling-Restrained Brace Arrangement in Regular RC Frames Based on Pushover Analysis

Abstract

To improve the seismic performance of existing reinforced concrete (RC) frame structures with insufficient lateral resistance, this study investigates the influence of different buckling-restrained brace (BRB) arrangements on a typical five-story, 4 × 4 bay regular RC frame. Based on the original benchmark model, four retrofit schemes were developed by considering two brace forms, namely single diagonal and chevron braces, and two planar locations, namely mid-bay and end-bay arrangements. Five numerical models, including one unstrengthened structure and four BRB-retrofitted structures, were established in SAP2000 V26 for nonlinear static pushover analysis. Geometric and material nonlinearities were incorporated to simulate the inelastic behavior of beams, columns, and BRBs. Pushover analyses were conducted under uniform and inverted triangular lateral load distributions to evaluate the global seismic performance of the structure. The results indicate that all retrofit schemes significantly enhanced the base shear capacity and deformation capacity of the original frame. Under the uniform load pattern, the maximum base shear capacities of the four strengthened models increased by 295%, 148%, 145%, and 148%, respectively, relative to the original structure. Under the inverted triangular load pattern, the corresponding increases were 232%, 128%, 124%, and 127%, respectively. Among the investigated configurations, the mid-bay single diagonal brace arrangement achieved the most effective improvement in lateral resistance and was identified as the optimal retrofit scheme. These findings demonstrate that mid-bay BRB placement is more effective than end-bay placement for enhancing the seismic performance of regular RC frame structures.