Optimal design of self-centering braced frames with limited self-centering braces

The self-centering brace (SCB) has drawn the attention of many researchers for its good seismic performance in reducing structural residual deformation due to earthquakes. However, the expensive cost of SCBs would act as a solid disincentive for practical application since stakeholders desire cost-effective structures. To this end, it is worth investigating how to achieve optimal self-centering efficiency with limited SCBs. This study introduced an optimal approach utilizing a genetic algorithm (GA) to optimally arrange a restricted number of SCBs within braced frames. The proposed GA-based method was validated through numerical analyses. Analytical outcomes revealed the method's efficiency in identifying the optimal positioning of SCBs within a braced frame, where limited SCBs were utilized. Besides, the interesting finding is that employing one set of SCBs with optimized position in the considered structure could yield a noteworthy reduction in residual deformation, ranging from a minimum reduction of approximately 59% to a maximum reduction of around 94%. The rise in peak inter-story drift and floor acceleration is constrained to a maximum of 2.71% and 7.6%, respectively. Additionally, the structural residual inter-story drift decreases as the number of SCBs in the structure increases, though the rate of decrease gradually diminishes. Conversely, the peak inter-story drift of the structure exhibits a linear increase with the number of SCBs. In contrast, the impact of the number of SCBs on the peak floor acceleration of the structure is relatively minor.