Cold‐Formed Steel Channel Struts

Abstract

Cold‐formed steel channel struts are structural elements often used in the fabrication of double‐layer grid‐space frames. Fabrication and assembly considerations sometimes require joint configurations that cause members to be eccentrically loaded. This paper reports a study of the behavior of eccentrically loaded, cold‐formed steel, lipped‐channel compression members of a space frame system. The behavior is separated into three regimes of prebuckling, buckling, and postbuckling responses. Beam‐column behavior and torsional‐flexural buckling are included. The primary response considered is the relationship between the axial force and shortening. The peak loads are given by the secant formula for negative eccentricities between the shear center and close to the centroid. For small negative eccentricities close to the centroid and for positive eccentricities, the torsional‐flexural buckling load controls. However, because of restraint of warping mechanisms at the supports, the capacity was greater than predicted. For larger positive eccentricities, the secant formula again controls. Three different postbuckling models for axial load versus shortening are investigated and show good agreement with the tests.