LATERAL BUCKLING STRENGTHS OF UNSHEETED COLD-FORMED BEAMS

This paper provides a survey of the state of knowledge on the lateral buckling strengths of unsheeted cold-formed steel beams. Topics includ ed are elastic lateral buckling, the effects of imperfections and resi dual stresses, and local and distortional buckling. Consideration is a lso given to the bending and torsion of eccentrically loaded channel b eams, the biaxial bending of Z-beams loaded in the plane of the web, a nd the distortional buckling of U-beams. It is found that design metho ds for cold-formed beams are derived from methods for hot-rolled colum ns, and that there are very few experimental results that can be used to assess present methods. A tentative new design approach to biaxial bending and torsion is proposed, but this cannot be properly assessed without experimental evidence of the strengths of eccentrically loaded channels and of Z-beams in biaxial bending.