General distortional buckling formulae for both fixed-ended and pinned-ended C-section columns

• Analytical formulae to estimate distortional critical stresses are proposed for both fixed-ended and pinned-ended C-section columns.
• The general distortional buckling formulae consistently yield accurate estimates for the two end support conditions addressed in this paper.
• The proposed formulae base on the Schafer’s DSM expressions can also provide more accurate ultimate load estimates.

This paper presents general explicit analytical formulae to provide distortional critical stress estimates for cold-formed steel C-section columns subjected to uniform compression. These formulae are derived by employing the Lau and Hancock model and by introducing a new factor for considering the web rotational restraint reduced by web bending. The results obtained from the general explicit analytical formulae are compared with the numerical results obtained from the computer programs CUFSM or/and GBTUL. For pinned-ended columns, these values are also compared with those yielded by the formulae developed by Lau and Hancock, Schafer, and Silvestre and Camotim. In particular, the distortional critical stress of fixed-ended C-section columns is validated by comparing the corresponding ultimate load based on Schafer’s DSM expressions with numerical results from the research literature. The formulae derived here are validated and their application, accuracy and capabilities are illustrated by these comparisons and validations.