Reassessment of the Lateral Torsional Buckling Resistance of Rolled I-Section Members: Moment Gradient Tests
Publication: Journal of Structural Engineering
Volume 143, Issue 4
Abstract
The lateral torsional buckling (LTB) equations in some current standards are based on unified equations that are a fit to a large body of experimental test data. However, these curves tend to overestimate the capacities from finite-element (FE) simulations based on typical idealized end conditions, residual stresses, and geometric imperfections. Uniform moment tests conducted on various types of cross sections have led to proposed modifications of the current specification for LTB equations. This paper investigates and recommends, by means of FE test simulations, the use of the modified equations with additional improvements for moment gradient cases. The emphasis of the studies is on rolled I-section members. Specifically, the paper demonstrates an inelastic effect that can be particularly significant for beams in which the maximum moment occurs within the unbraced length rather than at a braced point. A new way of applying the LTB modification factor, , in the inelastic LTB region for these cases is recommended for ordinary application of current standard resistance equations. Also, it is shown that this effect can also be captured seamlessly via an explicit inelastic buckling analysis using stiffness-reduction factors (SRFs) derived from the design resistance curves.
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Published In
Journal of Structural Engineering
Volume 143 • Issue 4 • April 2017
Copyright
©2016 American Society of Civil Engineers.
History
Received: Apr 21, 2016
Accepted: Sep 1, 2016
Published online: Oct 26, 2016
Discussion open until: Mar 26, 2017
Published in print: Apr 1, 2017
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