Tests of Cold‐Formed Channels with Local and Distortional Buckling

Abstract

Thin‐walled channel sections may undergo a mode of buckling, called distortional, in which a lip‐stiffened flange of the section rotates about the flange‐web junction. If the sections are composed of high‐strength steel, then there may be a significant postbuckling reserve of strength beyond the elastic distortional buckling stress in a similar manner to that which normally occurs for local buckling. The results of compression tests of thin‐walled channel section columns formed by brake‐processing are described. Two different section geometries, a simple lipped channel and a lipped channel with an intermediate stiffener in the web, were tested between fixed‐end boundary conditions. The geometries and yield strength were chosen to ensure that a substantial postbuckling strength reserve occurred in the distortional mode and that local buckling might occur simultaneously at a shorter wavelength. Distortional or mixed local‐distortional buckling stresses obtained from testing are compared with theoretical buc...