Warping of Joint in I-Beam Assemblages

A simple theory is developed for the coupled warping and crosssectional distortion at joints between thin-walled I-beams. Continuity of the joined flanges and the local character of the cross-sectional distortion permit the distortion deformation to be expressed in terms of the warping parameters of the two beams at the joint. Four types of joints are treated. The unstiffened joint has two independent warping parameters, the two partially stiffened joints each have a single warping parameter, while the fully stiffened joint prevents warping. The distortion mode acts as a local spring stiffness. The formulation is fully compatible with classical thin-walled beam theory, and detailed three-dimensional finite element analyses demonstrate high accuracy of the theory.