Distortion and Warping at Beam Supports
Publication: Journal of Structural Engineering
Volume 126, Issue 11
Abstract
When a doubly symmetric I-beam buckles elastically in a lateral-distortional mode, its web distorts, so that the two flanges have increased relative lateral displacements and may have different twist rotations. The centroid, shear center, and principal axes of the distorted cross section are all different from those of the undistorted cross section. The end connections to adjacent members may induce flange restraining moments that oppose warping deformations and modify the elastic buckling resistance. This paper investigates the effects on the lateral-distortional buckling of beams of web distortion and of the warping restraints induced by end-support conditions. It is found that a doubly symmetric I-section becomes unsymmetric during lateral-distortional buckling and that web distortion reduces the effective torsional and warping rigidities. The proposed approximations for the elastic lateral-distortional buckling resistances of beams without and with end warping restraints provide good predictions. Equations for the warping restraint stiffness induced by some commonly used end conditions are established. Comparisons with ABAQUS shell element results show that they provide good approximations.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 126 • Issue 11 • November 2000
Pages: 1279 - 1287
History
Received: Aug 31, 1999
Published online: Nov 1, 2000
Published in print: Nov 2000
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