Abstract
This paper deals with the characteristics of ultimate strength in the form of stress resultants, and then their interaction curves of unstiffened and stiffened thin-walled box stub columns subjected to compression, bending (including biaxial bending), torsion and their combinations are investigated based on an analytical method. This interaction curve for the ultimate stress resultants is verified through a parametric study based on elasto-plastic and finite displacement analysis by using F. E. M.