Inelastic Bending Capacity of Cold-Formed Steel Members
Publication: Journal of Structural Engineering
Volume 138, Issue 4
Abstract
The objective of this paper is to provide and verify a general design method for prediction of inelastic bending capacity in cold-formed steel members potentially subject to local, distortional, and/or lateral-torsional buckling modes. An extensive experimental database of tested cold-formed steel beams is collected and indicates that inelastic reserve in the bending capacity of thin-walled cold-formed steel members is more common than typically assumed. Elementary mechanics for inelastic reserve are reviewed and simplified expressions provided for connecting the strain demand to the inelastic bending capacity in the range between the yield moment and the fully plastic moment. The strain capacity that can be sustained in inelastic local and inelastic distortional buckling is investigated through existing experiments coupled with nonlinear finite-element (FE) analysis. The nonlinear FE models provide a comprehensive means to investigate the relationship between cross-section slenderness, normalized strain capacity, and the resulting bending strength. A design approach for inelastic lateral-torsional buckling is provided on the basis of the hot-rolled steel AISC Specification. The resulting relationships for inelastic local, distortional, and lateral-torsional buckling are provided in a Direct Strength Method format for potential adoption in the cold-formed steel American Iron and Steel Institute (AISI) Specification. The provided design method is assessed against available data and shown to be a reliable predictor of inelastic bending capacity in cold-formed steel members.
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Acknowledgments
The authors of this work would like to acknowledge the National Science Foundation for supporting this work under Grant No. 0448707 and the members of the AISI Committee on specifications for the invaluable assistance and recommendation in the course of development of this material. Only the authors’ views, and not necessarily those of the NSF or the AISI, are reflected in the material presented.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 138 • Issue 4 • April 2012
Pages: 468 - 480
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Mar 28, 2010
Accepted: Aug 2, 2011
Published online: Mar 15, 2012
Published in print: Apr 1, 2012
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