Multi-modal optimization for the seismic resistance of steel-frame structures by an improved red-billed blue magpie optimizer

This article proposes for the first time a multi-modal optimization design method for the seismic resistance of steel structures, focusing on minimizing inter-storey displacement angle and exploring various steel structure combinations to achieve optimal solutions. To cope with challenges, this article employs a novel multi-modal meta-heuristic algorithm incorporating a local search strategy as delineated in pbestmutation into the red-billed blue magpie optimizer. The optimization objective is to minimize the average of the maximum inter-storey drift of a structure subjected to three seismic intensity levels, based on nonlinear time-history analyses using Matlab® OpenSees, while ensuring compliance with strength, displacement and mass constraints of ASCE 7-16. To assess the efficacy of the algorithm, tests are conducted on 20 widely recognized multi-modal benchmark problems, showcasing its competitive superiority against existing algorithms. The capabilities and robustness of the algorithm are further examined through three case studies involving seismic-resistant steel-frame design.