Optimization of plated steel beams using metamodels and modern optimization methods

Abstract

This paper deals with metamodel-based optimization of plated steel beams. The first part of the article explains the principle of the metamodel-based optimization approach and also provides basic information on incorporated sub-methods such as design of experiments (DOE), mathematical approximation methods and mathematical optimization methods. Since optimized sections tend to be slender and thus susceptible to buckling, special attention is paid to the buckling evaluation. Both linear and nonlinear buckling analyses are employed. The nonlinear buckling analysis addresses detrimental influence of imperfections on the limit load by introducing equivalent geometric imperfections into the finite element (FE) model. The shapes and magnitudes of these imperfections are based on recommendations for plated beams given in Eurocode 3 (EC3). The practical part of the article illustrates the approach on step by step basis using an example of spreader beam weight optimization. It is shown that simple metamodels can efficiently substitute the FE model in optimization, thereby making the process very fast. The parametric FE models are developed in the Ansys Parametric Design Language (APDL). The governing algorithm, as well as most of the mathematical sub-methods, is realized in the Matlab software.