Seismic Performance Comparison of Steel Braced Frames with Buckling-Restrained Braces and Conventional Braces

The seismic performance analysis of a steel braced frame focuses on accurately simulating the strong nonlinear behavior of steel braces， including buckling and fracture. In OpenSEES software， a fiber beam-column element model with initial imperfection was used to simulate the buckling behavior of conventional steel braces （CBs）， while the Coffin-Manson relationship was employed to describe the low-cycle fatigue properties of both buckling-restrained braces （BRBs） and CBs.The hysteretic simulation results of the braces verified the method's feasibility. Based on this simulation approach， the seismic performance of buckling-restrained braced frames （BRBFs） and conventional braced frames （CBFs） was comparatively analyzed. Both systems were designed for the same building conditions following code requirements.The results showed that the area demand of the BRB was less than that of the CB， and the pushover curve of the CBF had a larger initial stiffness， while the buckling of the CB led to a sudden decrease in the structural bearing capacity.The structural responses of the BRBF were lower than those of the CBF under rare earthquakes. Under repeated strong earthquakes， some conventional braces （CBs） fractured， while all buckling-restrained braces （BRBs） remained intact.Compared to structural responses under rare earthquakes， both structural systems exhibited increased responses under repeated strong earthquakes， with conventional braced steel frames demonstrating greater response amplification than buckling-restrained braced frames.