Optimization of weight and collapse energy of space structures using the multi-objective modified crow search algorithm

Abstract

Due to the use of space structures in monumental and significant buildings, providing adequate safety and proper structural performance must always be taken into account. In this study, the geometric and material nonlinear behaviors are directly considered in the design of space structures so that the resulting designs are economical while having appropriate collapse behavior. Weight and collapse energy are considered the objective functions, and the problem is considered as a multi-objective optimization problem. This is the first attempt to combine the weight and collapse energy simultaneously for the optimal design of structures. To solve such problems, two new multi-objective algorithms based on the recently introduced crow search algorithm (CSA) have been proposed. These algorithms are called multi-objective crow search algorithm (MOCSA) and multi-objective modified crow search algorithm (MOMCSA). MOCSA and MOMCSA have similar structures and details, except that the MOCSA generates the new solution as the CSA approach does while generating the new solution in the MOMCSA is modified. The modification of the search vector and the search range is employed as two simple and effective changes in MOMCSA to enhance the exploration and exploitation. To evaluate the proposed algorithms, three space structures were optimized using the proposed algorithms and two well-known algorithms, MOPSO and NSGA-II. The results indicate superiority of MOMCSA to the other algorithms.