The Effects of Web Deformation on the Torsion of I-Beams

Abstract

Abstract An analysis of the I-beam in nonuniform torsion, as for instance, when a built-in end or section of symmetry is prevented from warping, is made which includes not only the bending of the flanges in their own planes (as considered previously by Timoshenko) but also a deformation of the web cross section. This extends the theory to thinner webs and permits the satisfaction of more general end conditions. Numerical examples worked out for three sections, differing in web thickness only, show that the stress and deformation are significantly modified by the web flexibility when the web is sufficiently thin, and that there are then bending stresses in the web which may be larger than the bending stresses in the flanges. Only the unbuckled state of the web is considered.