Lateral-Torsional Buckling of Stepped Beams with Continuous Bracing
Publication: Journal of Bridge Engineering
Volume 10, Issue 1
Abstract
Continuous span multibeam steel bridges are common along the state and interstate highways. The top flange of the beams is typically braced against lateral movement by the deck slab, and in many bridges the cross section is stepped at discrete points along the span. Design equations for lateral–torsional buckling (LTB) resistance in the American Association of State Highway and Transportation Officials “Load and resistance factor design bridge design specifications” are for prismatic beams and ignore the lateral restraint provided by the bridge deck. A new design equation is proposed that can be applied to I-shaped stepped beams with continuous top flange lateral bracing. By including the effects of the change in cross section size and the continuous top flange bracing, the calculated LTB resistance is significantly increased. Critical bending moment values from the proposed equation are compared to values from finite element method buckling analyses. The new equation is sufficiently accurate for use in design and in the evaluation of existing bridges.
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Acknowledgments
Results contained herein were obtained in connection with a research project “Remaining Fatigue Life of Interstate Highway Bridge,” Contract No. ALDOT 930-417, funded by the Alabama Department of Transportation and conducted by the Auburn University Highway Research Center. The funding, cooperation, and assistance of many people from these organizations is gratefully acknowledged.
References
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 10 • Issue 1 • January 2005
Pages: 87 - 95
Copyright
© 2005 ASCE.
History
Received: Nov 27, 2002
Accepted: Feb 17, 2004
Published online: Jan 1, 2005
Published in print: Jan 2005
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