Load Height and Moment Factors for Doubly Symmetric Wide Flange Beams
Publication: Journal of Structural Engineering
Volume 141, Issue 12
Abstract
An analytical procedure is used to study the effects of moment gradient and load height on the elastic stability of wide flange steel beams. Lateral torsional buckling is the limit state considered. Solutions are developed for a series of general moment functions which are produced by continuous load types with possible end moments. For each load type, an equivalent uniform moment factor is developed. Additionally, a load height factor is developed to modify the equivalent uniform moment factor for these load types where loading is applied above the shear center. Solutions are processed numerically using a Taylor series polynomial approximation. Results are presented in terms of an equivalent uniform moment factor and a load height factor. Comparison with national code procedures for moment factor show discrepancies that are conservative in some circumstances by up to 51% and unconservative in others by up to 8%. The largest discrepancies occur under the effect of reverse curvature bending and load position above the shear center. Results for load position show that members loaded above their shear center are more susceptible to lateral torsional buckling than those loaded at their shear center. Some design examples are presented using the load height factors developed.
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Published In
Journal of Structural Engineering
Volume 141 • Issue 12 • December 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Nov 10, 2014
Accepted: Mar 24, 2015
Published online: May 18, 2015
Discussion open until: Oct 18, 2015
Published in print: Dec 1, 2015
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