A robust method for optimization of semi-rigid steel frames subject to seismic loading

In this study, we develop a seismic optimization method to minimize the semi-rigid steel frame cost. In the proposed method, cross-sections of columns and beams and types of beam-to-column and base restraint semirigid joints are considered as the design variables of the optimization. The nonlinear seismic behaviors of the structure are carried out by using plastic-hinge beam-column elements for beams and columns, zero-length elements for semi-rigid connections, and time-history dynamic analysis. An effective implementation of harmony search technique (HS) is presented to find the global optimal solution of the optimization. In order to improve HS, a multi-comparison technique (MCT) is proposed that significantly reduces the useless timeconsuming evaluations in the optimization. The robustness and efficiency of the proposed method are demonstrated through three optimization problems of semi-rigid steel frames. Compared with particle swarm optimization (PSO), micro-genetic algorithm (micro-GA), and genetic algorithm (GA), the proposed method is found to significantly reduce the number of structural analyses required and yield the better optimum frame designs. (C) 2017 Elsevier Ltd. All rights reserved.