Performance based optimal seismic design of steel moment frame using nonlinear dynamic analysis and particle swarm optimization algorithm

Due to the importance of economic issues in building constructions, in recent decades, many studies have been performed on structural design optimization to reduce the constructional costs in various stages. Meanwhile, the structural weight is one of the important objective functions that is often applied to structural design optimization. In this study, a new single-objective optimization problem is proposed for performance based seismic design of two-dimensional steel moment resisting frame using nonlinear dynamic analysis based on the recent design codes. The objective function is defined as the weight of the frame, which should be minimized subject to some design constraints including section size compatibility, serviceability and performance-based limitations. As a well-known meta-heuristic method, particle swarm optimization (PSO) algorithm is utilized for solving this continuous optimization problem. Nonlinear dynamic analysis is employed for performance based seismic design based on specific seismic performance and seismic hazard levels. Since nonlinear time history analysis considers both material and geometric nonlinearities, it is the best choice to obtain accurate and realistic results among other seismic analysis methods. Also, spectral matching method is used for the scaling procedure of eleven accelerograms. Design example shows applicability and capability of the proposed optimization problem as well as the PSO algorithm.