SIZE, SHAPE AND TOPOLOGY OPTIMIZATION OF COMPOSITE STEEL BOX GIRDERS USING PSO METHOD

Bridges with composite steel box girders are used at the intersection of many modernbridges. Heuristic optimization methods are the new techniques developed in the last twodecades that employ stochastic approaches. This paper deals with the size, shape andtopology optimization of composite steel box girders using Particle Swarm Optimization(PSO) method. The advantage of using PSO compared to gradient based techniques lies in the fact that the discrete spaces can be optimized in a simple manner. This algorithm was written in Python language in the finite element analysis software, ABAQUS, environment as a script file. The objective function is the minimization of total weight of the structure under strength and serviceability constraints, enforced by penalty functions. All design requirements correspond to the American Association of State Highway and Transportation Officials (AASHTO) and Iranian Codes of Practice (ICP) for Loading of Bridges Compared to a conventional feasible design, the optimum solution showed a 55% reduction of structural weight.