Collapse-performance-aided design optimization of steel concentrically braced frames

This study focuses on collapse-performance-aided optimization of steel concentrically braced frame (SCBF) structures optimized in the framework of performance-based design. The proposed methodology in this paper consists of three steps. The first step involves tackling the problem of seismic performance-based size and topology optimization of SCBFs. In the second step, incremental dynamic analysis (IDA) is performed to generate IDA and fragility curves for all the obtained optimal designs. Subsequently, their collapse margin ratios are calculated. In the last step, the SCBFs with fixed and optimal placement of bracings are compared in terms of structural weight and seismic collapse capacity. The efficiency of the proposed methodology is illustrated by presenting three numerical examples of 5-, 10-, and 15-story SCBFs with fixed and optimal topology of braces. The results demonstrate that the topologically optimal SCBFs not only have the least structural weight, but also they are of considerable collapse safety in comparison to optimal SCBFs with fixed topology of braces.