Post local buckling strength of bi-axially loaded slender I-section columns

Slender section columns can carry additional loads up to failure after local buckling has happened in its elements. This post-local buckling capacity depends mainly on the width-thickness ratios of elements forming the section as well as the state of stresses within it. This paper presents tests to examine the influence of these factors on this additional capacity. The experimental local buckling and ultimate loads of two series of specimens are presented. Each series contains a group of slender I-sections varying in their flange and web width-thickness ratios. In the first series the loads are applied axially through the CG. of the sections, while in the other one they are applied eccentrically about the major and minor axis. Additionally, the tested specimens are simulated numerically by a non-linear finite element model considering different values of overall geometric imperfections. Generally, the post-local buckling strength gained by the sections is higher for axially loaded columns than that of bi-axially loaded ones, and it decreases with increasing eccentricity for the same web and flange width-thickness ratios.