Design of lipped channel columns

Abstract

The paper describes a series of tests on lipped channels compressed between fixed ends. Complete column curves were obtained for two cross sections with different flange slenderness. Detailed measurements were conducted of the material properties, residual stresses, and local and overall geometric imperfections. The test strengths are compared with the rules of the Australian, American, and European specifications for cold-formed steel structures. It is shown that a fixed-ended channel column can be designed using an effective length of one-half of the column length and assuming the applied force acts at the centroid of the effective section. Pin-ended column tests of the same cross sections were conducted for reference. It was shown that the current design rules lead to very conservative predictions. The shift of the effective centroid, as predicted by the Australian and American specifications, was shown to be inaccurate compared with the tests for the cross section with slender flanges. This led to the abnormal result of an increase in column strength with increasing length.