Multi-objective Optimization Design of Buckling-Restrained Braced Frames Based on Performance Evaluation and Risk of Repair Cost and Time

Buckling-restrained braced frames (BRBFs) present a kind of lateral bracing system characterized by their remarkable high-energy dissipation capacity. This study focuses on two BRBFs within 2- and 6-story structures. The frames are meticulously modeled within the OpenSees software. The investigation employs the multi-objective particle swarm optimization (MOPSO) algorithm to ascertain the optimal stiffness modification factor for the braces. This factor is influenced by diverse aspects, including brace length and cross-sectional area—key components in synthesizing the brace structure. The objective of brace optimization lies in minimizing building repair time and cost, necessitating a comprehensive risk assessment. Throughout the optimization procedure, performance evaluation is conducted using the methodology outlined in FEMA P-58. Each optimization stage involves an analysis of the braces utilizing Incremental Dynamic Analysis (IDA) across 22 earthquake records to assess their performance. The optimization outcomes unveil a distinct trend: for a 2-story building, lower values of the stiffness modification factor engender an optimal risk profile concerning repair time and cost. Conversely, a 6-story building tends toward higher values of the stiffness modification factor to achieve an optimal balance between repair time and cost.