Distortional Buckling Tests on Cold-Formed Steel Beams
Publication: Journal of Structural Engineering
Volume 132, Issue 4
Abstract
Failure in cold-formed steel beams is generally initiated by one of three instabilities: local, distortional, or lateral-torsional buckling. For cold-formed steel joists, purlins, or girts, when the compression flange is not restrained by attachment to sheathing or paneling, distortional buckling may be the predominant failure mode. Experimental results on cold-formed steel beams with unrestrained compression flanges are scarce. Therefore a series of distortional buckling tests on cold-formed steel C and Z sections in bending was conducted to establish the capacity in distortional buckling failures. Test details were selected to allow distortional buckling to form, but restrict lateral-torsional buckling to the extent possible. These distortional buckling tests also provide a direct comparison against the local buckling tests previously performed by the writers. As expected, large strength reductions are observed in the tested specimens when distortional buckling initiated the failure instead of local buckling. U.S., Canadian, and joint North American standards for design, which are known to primarily focus on local buckling, provided unconservative predictions of the observed strength. The Australian/New Zealand Standard and the direct strength method, which provide explicit methods for calculating the capacity in the distortional buckling mode, provided reasonably accurate and reliable predictions.
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Acknowledgments
The sponsorship of the American Iron and Steel Institute (AISI) for both phases of this work, and the Metal Building Manufacturers Association for the first phase is gratefully acknowledged. Donation of materials by Varco-Pruden, Clark Steel, and Dietrich Design Group is also gratefully acknowledged. The assistance of the AISI task group in developing the testing plan is appreciated. Don Johnson, Maury Golovin, Joe Nunnery, Joe Wellinghoff, and Steve Thomas have all been helpful with their ideas and generous with their time. Special thanks go to Sandor Ádány from Budapest University of Technology and Economics, who helped on the Eurocode calculation. The experiments would not have been possible without the help of Johns Hopkins undergraduates: Liakos Ariston, Brent Bass, Andrew Myers, Sam Phillips, and Tim Ruth. Sam’s work during Phase 1 and Tim’s during Phase 2 was particularly helpful. Finally, the work has been skillfully aided by our laboratory technician Jack Spangler, and our machinist Jim Kelly.
References
ABAQUS version 6.2.; users manual. (2001) ABAQUS, Inc., Pawtucket, R.I., (www.abaqus.com).
American Iron and Steel Institute (AISI). (1996). Specification for the design of cold-formed steel structural members, Washington, D.C.
American Iron and Steel Institute (AISI). (2001). North American specification for the design of cold-formed steel structural members, Washington, D.C.
American Iron and Steel Institute (AISI). (2004). Supplement 2004 to the North American specificaiton for the design of cold-formed steel structural members, 2001 edition, Appendix 1, design of cold-formed steel structural members using direct strength method, Washington, D.C.
American Society for Testing and Materials (ASTM). (2000). E8-00, Standard test methods for tension testing of metallic material, Philadelphia.
Canadian Standards Association (CSA). (1994). Cold-formed steel structural members S136-94, Ontario, Canada.
Desmond, T. P., Peköz, T., and Winter, G. (1981). ”Edge stiffeners for thin-walled members.” J. Struct. Div. ASCE, 107(2), 329–353.
Comité Européen de Normalisation (CEN). (2002). “Eurocode 3: Design of steel structure.” European Standard EN1993-1-3, CEN, Brussels, Belgium.
Hancock, G. J. (1997). “Design for distortional buckling of flexural members.” Thin-Walled Struct., 27(1), 3–12.
Hancock, G. J., Rogers, C. A., and Schuster, R. M. (1996). “Comparison of the distortional buckling method for flexural members with tests.” 13th Int. Specialty Conf. on Cold-Formed Steel Structures, 125–140, St. Louis.
Schafer, B. W. (2005). CUFSM 2.6: Elastic buckling analysis of thin-walled members by finite strip analysis, (www.ce.jhu.edu/bschafer/cufsm).
Schafer, B. W. (2002). “Local, distortional, and Euler buckling in thin-walled columns.” J. Struct. Eng., 128(3), 289–299.
Schafer, B. W., and Peköz, T. (1998). “Direct strength prediction of cold-formed steel members using numerical elastic buckling solutions.” 14th Int. Specialty Conf. on Cold-Formed Steel Structures, St. Louis.
Schafer, B. W., and Peköz, T. (1999). “Laterally braced cold-formed steel flexural members with edge stiffened flanges.” J. Struct. Eng. 125(2), 118–127.
Schafer, B. W., and Trestain, T. (2002). “Interim design rules for flexure in cold-formed steel webs.” 16th Int. Specialty Conf. on Cold-Formed Steel Structures, Orlando, Fla.
Silvestre, N., and Camotim, D. (2004). “Distortional buckling formulae for cold-formed steel C and Z-section members: Part I—Derivation.” Thin-Walled Struct., 42(11), 1567–1597.
Standards Australia and the Australian Institute of Steel Construction (AS/NZS). (1996). AS/NZS 4600: 1996 Cold-Formed Steel Structures.
Yu, C. (2005). “Distortional buckling of cold-formed steel members in bending.” Ph.D. dissertation, Johns Hopkins Univ., Baltimore.
Yu, C., and Schafer, B. W. (2003). “Local buckling test on cold-formed steel beams.” J. Struct. Eng., 129(12), 1596–1606.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 132 • Issue 4 • April 2006
Pages: 515 - 528
Copyright
© 2006 ASCE.
History
Received: Feb 9, 2005
Accepted: Jun 27, 2005
Published online: Apr 1, 2006
Published in print: Apr 2006
Notes
Note. Associate Editor: Donald W. White
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