Linear buckling optimization and post-buckling behavior of optimized cold formed steel members

Abstract

Today's high-strength materials allow for significant increases in working and limit stresses. To fully exploit material improvements as weight savings on structures, it is desirable to enhance the performance of structural components. The work presented in this paper proposes that the buckling behavior of cold form steel columns may be effectively improved without increased material volume. In order to achieve this goal, optimization algorithm which integrates finite strip analysis, geometric modeling, semi analytical sensitivity analysis and sequential quadratic mathematical programming methods can be used to find an optimum cross section of cold-formed steel columns under axial compression. The objective is the maximization of the critical buckling load with constraints on the volume of material used. Several examples are included to illustrate advantage of the optimization. The post buckling performance of optimized cold form steel columns was also investigated using nonlinear variable thickness finite strip analysis. Non-linear finite strip analysis helped to understand the behaviour of these cold form steel columns and select the most promising designs. The optimum forms found in this paper can be used to develop improved designs for cold formed steel columns. Key words: Cold formed steel, column buckling, optimization.