Restrained Warping in Cruciform Compression Members

Abstract

Equal‐leg angle cruciform members are known to be prone to torsional buckling. The primary parameters controlling torsional buckling mode are the width/thickness ratio of the outstanding legs, and the degree of warping restraint provided by the supports, the interconnectors, and the separation gap between the angles. Results are reported of an analytic and numerical study on the effects of warping restraint on the torsional stiffness and on the torsional buckling capacity. The study investigates the effect of different warping restraints, interconnector spacings, and gap separations on the torsional rigidity of four equal‐leg angle cruciforms. The effective torsional rigidity is used in analytic predictions of torsional buckling critical stresses, which are compared with finite‐element, geometrically nonlinear analyses. Recommendations are made for design, and future research directions are suggested.