Improved design rules for fixed ended cold-formed steel columns subject to flexural

Improved design rules for fixed ended cold-formed steel columns subject to flexural–torsional buckling

Gunalan, Shanmuganathan / Mahendran, Mahen

Abstract This paper has presented the details of an investigation into the flexural and flexural–fl buckling behaviour of cold-formed structural steel columns with pinned and fixed ends. Current design rules for the member capacities of cold-formed steel columns are based on the same non-dimensional strength curve for both fixed and pinned-ended columns. This research has reviewed the accuracy of the current design rules in AS/NZS 4600 and the North American Specification in determining the member capacities of cold-formed steel columns using the results from detailed finite element analyses and an experimental study of lipped channel columns. It was found that the current Australian and American design rules accurately predicted the member capacities of pin ended lipped channel columns undergoing flexural and flexural torsional buckling. However, for fixed ended columns with warping fixity undergoing flexural–torsional buckling, it was found that the current design rules significantly underestimated the column capacities as they disregard the beneficial effect of warping fixity. This paper has therefore proposed improved design rules and verified their accuracy using finite element analysis and test results of cold-formed lipped channel columns made of three cross-sections and five different steel grades and thicknesses.

Highlights • Numerical studies of cold-formed steel lipped channel columns are conducted. • Pinned and fixed ended columns with warping free and fixed conditions are studied. • Capacities of columns subject to flexural and flexural torsional buckling are studied. • Conservative designs for fixed end and warping fixed columns in flexural–torsional buckling. • Improved design rules are proposed for these fixed ended columns.