Optimization of Single-Objective and Multi-Objective Special Truss Moment Frame Using Island Genetic Algorithm

In many optimization studies, the goal is to minimize the costs which is necessary due to the limited resources and energy and the constantly increasing costs. However, this reduction in costs must be to some extent so that the expected performance of the structure is not impaired. In this study, the aim is to optimize the seismic performance and the weight of the structure simultaneously. In order to demonstrate the seismic performance of the structure, a criterion is needed to represent the seismic performance of the structure, for which the behavior coefficient parameter is used. In this paper, the optimal design of a special moment resisting frame is performed using the island genetic algorithm, once under a single-objective, objective function with the aim of minimizing the weight and again under a multi-objective, objective function with the aim of minimizing weight and maximizing behavior coefficient simultaneously. For this purpose, the design of 3 frames of 3, 6 and 9 stories with one span with a story height of 3 meters and span length of 18 meters is presented. In this research, truss arrangement, cross section of truss members, truss height and length of special zone of the truss moment resisting frame are optimized. The optimization code is written in Matlab software environment and OpenSees software is used for structural analysis. The constraints of optimization problem are based on the regulations and restrictions of AISC341-16. Finally, the results of the single-objective and multi-objective optimization are compared. The results show the efficiency and performance of the two-objective, objective function method in comparison with the single-objective, objective method.