Laterally Braced Cold-Formed Steel Flexural Members with Edge Stiffened Flanges
Publication: Journal of Structural Engineering
Volume 125, Issue 2
Abstract
The moment capacity of a laterally braced cold-formed steel flexural member with edge stiffened flanges (e.g., a channel or zee section) may be affected adversely by local or distortional buckling. New procedures for hand prediction of the buckling stress in the local and distortional mode are presented and verified. Numerical investigations are employed to highlight postbuckling behavior unique to the distortional mode. Compared with the local mode, the distortional mode is shown to have (1) heightened imperfection sensitivity, (2) lower postbuckling capacity, and (3) the ability to control the failure mechanism even in cases when the elastic buckling stress in the local mode is lower than in the distortional mode. Traditional design methods do not explicitly recognize distortional buckling, nor do they account for the observed phenomena in this mode. A new design method that integrates distortional buckling into the unified effective width approach, currently used in most cold-formed steel design specifications, is presented. For each element a local buckling stress and a reduced distortional buckling stress are compared to determine the effective width. Comparison with experimental tests shows that the new approach is more consistent and reliable than existing design methods.
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References
1.
American Iron and Steel Institute (AISI). ( 1996). AISI specification for the design of cold-formed steel structural members. American Iron and Steel Institute, Washington, D.C.
2.
Canadian Standards Association. ( 1994). S136-M94 cold-formed steel structural members, Rexdale (Toronto), ON, Canada.
3.
Cheung, Y. K. ( 1976). Finite strip method in structural analysis. Pergamon, Pergamon, New York.
4.
Cohen, J. M. ( 1987). “Local buckling behavior of plate elements.” Dept. of Struct. Engrg. Rep., Cornell University, Ithaca, N.Y.
5.
Davies, J. M., and Jiang, C. ( 1996). “Design of thin-walled beams for distortional buckling.” Proc., 13th Int. Spec. Conf. on Cold-Formed Steel Struct., W. W. Yu and R. A. Laboube eds., University of Missouri, Rolla, Mo., 141–154.
6.
Desmond T. P., Peköz, T., and Winter, G. (1981). “Edge stiffeners for thin-walled members.”J. Struct. Div., ASCE, 107, 329–353.
7.
Elhouar, S., and Murray, T. M. ( 1985). “Adequacy of proposed AISI effective width specification provisions for Z- and C-purlin design.” Rep. No. FSEL/MBMA 85-04, Fears Structural Engineering Laboratory, University of Oklahoma, Norman, Okla.
8.
Ellifritt, D., Glover, G., and Hren, J. ( 1997). “Distortional buckling of channels and zees not attached to sheathing.” Rep. No. 4504530-12, American Iron and Steel Institute, Washington, D.C.
9.
Ellifritt, D., Sputo, T., and Haynes, J. ( 1992). “Flexural capacity of discretely braced C's and Z's.” Proc., 11th Int. Spec. Conf. on Cold-Formed Steel Struct., W. W. Yu and R. A. Laboube eds., University of Missouri, Rolla, Mo., 109–129.
10.
Hancock, G. J. ( 1995). “Design for distortional buckling of flexural members.” Proc., 3rd Int. Conf. on Steel and Aluminum Struct., G. A. Aşkar, ed., Boaziçi University, Istanbul, Turkey, 275–284.
11.
Hancock, G. J. ( 1997). “Design for distortional buckling of flexural members.” Thin-Walled Struct., 27(1), 3–12.
12.
Hancock, G. J., Kwon, Y. B., and Bernard, E. S. ( 1994). “Strength design curves for thin-walled sections undergoing distortional buckling.” J. Constr. Steel Res., 31(2-3), 169–186.
13.
Hancock, G. J., Rogers, C. A., and Schuster, R. M. ( 1996). “Comparison of the distortional buckling method for flexural members with tests.” Proc., 13th Int. Spec. Conf. on Cold-Formed Steel Struct., W. W. Yu and R. A. Laboube eds., University of Missouri, Rolla, Mo., 125–140.
14.
Hibbitt, Karlsson & Sorensen, Inc. (HKS). ( 1995). ABAQUS version 5.5 . Hibbitt, Karlsson & Sorensen, Pawtucket, R.I.
15.
LaBoube, R. A., and Yu, W. ( 1978). “Structural behavior of beam webs subjected to bending stress.” Civil engineering study structural series, Rep. 78-1, Department of Civil Engineering, University of Missouri-Rolla, Rolla, Mo.
16.
Lau, S. C. W. ( 1988). “Distortional buckling of thin-walled columns,” PhD thesis, University of Sydney, Sydney, Australia.
17.
Lau, S. C. W., and Hancock, G. J. (1987). “Distortional buckling formulas for channel columns.”J. Struct. Engrg., ASCE, 113(5), 1063–1078.
18.
Moreyra, M. E. ( 1993). “The behavior of cold-formed lipped channels under bending,” MS thesis, Cornell University, Ithaca, N.Y.
19.
Peköz, T. ( 1987). “Development of a unified approach to the design of cold-formed steel members.” AISI Res. Rep. No. CF 87-1, American Iron and Steel Institute, Washington, D.C.
20.
Rogers, C. A., and Schuster, R. M. ( 1995). “Interaction buckling of flange, edge stiffener and web of C-sections in bending.” Res. Into Cold Formed Steel, Final Rep. of CSSBI/IRAP Proj., Department of Civil Engineering, University of Waterloo, Waterloo, Canada.
21.
Schafer, B. W., and Peköz, T. P. ( 1998). “Computational modeling of cold-formed steel: Characterizing geometric imperfections and residual stresses.” J. Const. Steel Res., 47(3), 193–210.
22.
Schardt, R., and Schrade, W. ( 1982). Kaltprofil-Pfetten . Institut Für Statik, Technische Hochschule Darmstadt, Bericht Nr. 1, Darmstadt, Germany (in German).
23.
Schuster, R. M. ( 1992). “Testing of perforated C-stud sections in bending.” Report for the Canadian Sheet Steel Building Institute, University of Waterloo, Waterloo, ON, Canada.
24.
Seah, L. K., and Rhodes, J. (1993). “Simplified buckling analysis of plate with compound edge stiffeners.”J. Engrg. Mech., ASCE, 119(1), 19(1), 19–38.
25.
Shan, M., LaBoube, R. A., and Yu, W. ( 1994). “Behavior of web elements with openings subjected to bending, shear and the combination of bending and shear.” Civil Engineering Study Structural Series, Rep. 94-2, Department of Civil Engineering, University of Missouri-Rolla, Rolla, Mo.
26.
Sharp, M. L. (1966). “Longitudinal stiffeners for compression members.”J. Struct. Div., ASCE, 102, 187–211.
27.
von Kármán, T., Sechler, E. E., and Donnell, L. H. ( 1932). “The strength of thin plates in compression.” Trans. ASME, 54, 53–57.
28.
Willis, C. T., and Wallace, B. (1990). “Behavior of cold-formed steel purlins under gravity loading.”J. Struct. Engrg., ASCE, 116(8), 2061–2069.
29.
Winter, G. ( 1947). “Strength of thin steel compression flanges.” Trans. ASCE, Paper No. 2305, 112, 1–50.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 125 • Issue 2 • February 1999
Pages: 118 - 127
History
Received: Feb 2, 1998
Published online: Feb 1, 1999
Published in print: Feb 1999
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