Water Cycle Algorithm’s Applications To The Structural Optimal Design And Its’ Improvements In The Multi-objective Optimization

Swarm intelligence algorithms have been proved to be successful algorithms in solving practical engineering optimization problems. In traditional optimization design method, that is lack of a principle of how to deal with the engineering constraints. However, with the rapid development of the information technology, nowadays there are a lot of algorithms to research how to treat and control engineering constraints. Water Cycle Algorithm (WCA) can solve this kind of engineering problems. This paper applies WCA to structure optimization design in continuous and discrete variables, and improves Water Cycle Algorithm for the single-objective optimization into a multi-objective optimization algorithm MWCA. Setup an elite set to store the Pareto optimum solutions found in the iterative process, and use the crowding distance for maintaining the elite set, which makes the algorithm get a uniform Pareto optimal front.This article simply introduces the structure optimization design and the development process of the algorithm, and expounds the basic theory of water cycle algorithm, calculation steps and process, and its application in structural optimization design. The research content of this article is divided into two parts:Firstly, this paper will use WCA in single objective optimization design in the actual project, and implements the truss structure cross-section optimization, shape optimization and optimization of frame structure. The third chapter selects the total weight of the structure as the objective functions for size optimization,2frame structures were taken as examples. The forth chapter in this paper selects the total weight of the structure as the objective function, and17-bar planar truss,25-bar space truss and72-bar space truss were optimized for size optimization. The fifth chapter selects the total weight of the structure and the optimal space as the objective functions for shape optimization,6truss structures were taken as examples. Secondly, this paper will apply WCA in multi-objective optimization design in the actual projects, carry out the total weight, shape and the maximum displacement of the specified nodes of the truss structures. For the steel frame structures, the total weight of the structure, the total dynamic strain energy and the maximum level drift were chosen as the objective functions. In chapter six, two truss structures and two frame structures were taken as examples.The results show that WCA can effectively solve the single and multi-objective optimization problems of actual constructions, and provide a faster convergence rate and a better solution than other algorithms.