Efficient use of materials in making structures is the main purpose of it. Since the construction of building structures need high costs. Hence, designers and professionals want to build structures that are economically justified and appropriate and also designs also meet predetermined objectives. However, optimization of the structures of buildings are the priority because thay are the most common and the most important structures due to more general use by human. Therefore, in this thesis, optimization of steel moment frames three, six and nine storeys in order to reduce structural weight which is a measure of the cost of its construction, in compliance with regulations and provisions of the strength of the force of the earthquake, has been investigated.
Since classical algorithms, are not effectively able to find the global optimum in a large search space with more variable numbers, in this research CSS methods known as randomized algorithms were used for optimization such as:, particle swarm algorithm (PSO) . In the following, the optimal structures designed by these algorithms were evaluated based on FEMA-356 and improvment instructions.
In order to validate the accuracy of the algorithms, the results of algorithms were compared in the run-time, the optimal solution is obtained, the number of repetitions and frequency of use of the objective function.