Optimum design of thin-plated steel box columns

This paper deals with the optimum design of thin-plated box columns subjected to axial thrust and biaxial end moments. Design formulae based on an effective width approach, proposed by the authors, are utilized in the optimization studies. The problem is first viewed as a strength maximization problem in which the optimum plate slenderness is evaluated for columns having constant weight of material. Results are presented in the form of nondimensional charts so that they can be used for practical design. The problem is then viewed as a minimum weight design problem and solved by means of the SUMT method. Side constraints, such as minimum plate thickness requirements are imposed during the optimization process to study their effects on the design of box sections. Results are presented in terms of cross-sectional dimensions and minimum weights for columns having different proportions and subjected to different end loadings.