Eccentrically Loaded Steel Columns under Cyclic Out-of-Plane Loading

Abstract

This paper is aimed at evaluating the ultimate strength and ductility capacity of steel pipe section columns subjected to cyclic out-of-plane transverse loading as well as the constant in-plane eccentric vertical load. A finite-element formulation accounting for both geometrical and material nonlinearity is developed to obtain the inelastic behavior of the columns. In the analysis, a modified two-surface plasticity model is employed to predict the cyclic characteristics of steel. An extensive parametric study has been carried out to investigate the effect of radius-thickness ratio, column slenderness ratio, and eccentric distance on the strength and ductility of the columns. It is found that the ultimate strength and ductility formulas proposed by the writers for the centrally loaded columns are also applicable to those of the eccentrically loaded columns subjected to cyclic out-of-plane loading, as long as a modification coefficient of initial structural stiffness is employed to multiply the computed results.