Optimization Of The Frame Based On Particle Swarm Algorithm

Nowadays, when solving the structural optimization problems under numerous constraints, the most important task is to quickly and accurately achieve the best performance and economic engineering demand. In engineering, both trusses and frames are common structural forms. However, because trusses mainly bear axial force which is relatively simple, the structural optimization usually choose truss structures as the research model. Although frame structures are more common than trusses in reality, significantly less rigid frame structures are choosen as the model of structure optimization because of its complex loading and deformation. In this paper, the two core questions are the improvement of particle swarm optimization (PSO) algorithm and the application of the improved PSO algorithm to optimization design of the frame structures. The main content of this article are summarized as the following:1、Using standard PSO to optimize frames or frame-and-truss composite structures with continuous variables. Through comparing its results with some traditional methods(modified method of feasible directions, sequential linear algorithm and sequential quadratic programming), PSO is verified to be feasible in the optimization design of rigid frames and composite structures with continuous variables. At the same time, it is shown that PSOhas more excellent performance than the traditional algorithms.2、For optimization problems with equal-step-length discrete variables or set-value discrete variables, this paper discretizes continuous variables firstly and then checks whether the obtained discrete variables meet constraints or not, which is different from literatures. In the literatures checking constraints generally took place before taking conservative discrete values. Two examples of frame structures with discrete variables verify the applicability of the proposed method.3、Adaptive inertia weight and the asynchronous model are utilized to improve particle swarm optimization algorithm. Comparing its results with unimproved discrete particle swarm optimization algorithm in the discrete variable optimization of frame structures proves that the improved PSO algorithm has more advantages.4、Based on "the technical specification for portal frame light steel structure houses", the optimization design of portal rigid frame is accomplished using discrete particle swarm optimization algorithm. By comparison with the results in literatures, it is illustrated that the proposed discrete particle swarm optimization algorithm, achieves ideal results and is superior. What’s more, the paper compared the efficiency for different number of design variables. The results indicated that using more design variables can significantly decrease the steel consumption but would not obviously increase the calculation amount.