Elastic lateral-torsional buckling of general cold-formed steel beams under uniform moment

• Published in: Thin-walled structures Vol. 119; pp. 586 - 592
• Main Author: Glauz, R.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2017
• Subjects: Cold-formed steel; Lateral-torsional buckling; Non-principal axes; Non-symmetric sections; Non-symmetric sections; Cold-formed steel; Lateral-torsional buckling; Non-principal axes
• ISSN: 0263-8231; 1879-3223
• DOI: 10.1016/j.tws.2017.07.010

The design of unbraced cold-formed steel beams must consider lateral-torsional buckling due to the low torsional stiffness associated with open cross-sections. The American Iron and Steel Institute incorporated design equations for the critical elastic lateral-torsional buckling stress in the North American Specification for the Design of Cold-Formed Steel Structural Members. These equations are based on elastic theory for singly-symmetric and doubly-symmetric sections. However, the equation for point-symmetric sections is only a rough approximation. Furthermore, there are no provisions for lateral-torsional buckling of non-symmetric sections, or sections oriented to non-principal axes. This paper investigates and develops a general formulation of the lateral-torsional buckling equation to broadly cover all cold-formed steel cross-sections. [Display omitted] •A general form of the lateral-torsional buckling equation has been developed.•This equation is applicable to non-symmetric shapes oriented to non-principal axes.•Numerical methods provided results with good agreement.•Predictions for point-symmetric sections are improved over current specifications.•This solution benefits the engineer so that more complex methods are not required.