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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 93
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru and M.L. Romero
Paper 114

Distortional Buckling of Stiffened Cold-Formed Steel Channel Sections

H.R. Naderian1, M. Azhari2 and H.R. Ronagh3

1Department of Civil Engineering, Yazd University, Iran
2Department of Civil Engineering, Isfahan University of Technology, Iran
3School of Civil Engineering, University of Queensland, Brisbane, Australia

Full Bibliographic Reference for this paper
H.R. Naderian, M. Azhari, H.R. Ronagh, "Distortional Buckling of Stiffened Cold-Formed Steel Channel Sections", in B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru, M.L. Romero, (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 114, 2010. doi:10.4203/ccp.93.114
Keywords: buckling, distortional, cold-formed, channel sections, complex finite strip method, stiffened.

Summary
This paper proposes a semi-analytical complex finite strip method to analyze the distortional buckling of cold-formed steel channel section columns and beams. The main purpose of this paper is to study the buckling behavior of cold-formed channel sections with extra longitudinal stiffeners at the end of flanges and also on the web. For a better understanding of the buckling in cold-formed channel sections, the elastic local, flexural-torsional, and lateral-torsional buckling modes have also been considered in addition to distortional buckling. One of the most important purposes of this study is to investigate the optimum width of extra longitudinal flange stiffeners in cold-formed channel sections.

The critical stresses using a complex finite strip method can be evaluated by solving eigenvalue problem for each half-wavelength [1]. It should be noted that this method result in members that are simply-supported. More complicated boundary conditions may be treated [2] but are not discussed here. For validation purposes, the complex finite strip method results are compared with those obtained using an analysis based on the generalized beam theory [3] and a virtually perfect coincidence was found.

The effect of an extra longitudinal flange stiffener on the distortional buckling behavior of channel section columns and beams is examined. It will be concluded that that the maximum distortional critical stress in stiffened C sections occurs in a specific ratio of the width of the extra stiffener to the flange width. The method is used to investigate the optimum position of the longitudinal web stiffener in cold-formed E section columns for local and distortional buckling modes. Using the semi-analytical complex finite strip method, a comparison on the buckling behavior of unstiffened and stiffened cold-formed channel sections in local, distortional and global modes will be made.

References
1
R.J. Plank, W.H. Wittrick, "Buckling Under Combined Loading of Thin Flat Walled Structures by a Complex Finite Strip Method", International Journal for Numerical Methods in Engineering, 8, 323-339, 1974. doi:10.1002/nme.1620080211
2
M.A. Bradford, M. Azhari, "Buckling of Plates With Different End Conditions Using the Finite Strip Method", Journal of Computers & Structures, 56(1), 75-83, 1995. doi:10.1016/0045-7949(94)00528-B
3
P.B. Dinis, D. Camotim, N. Silvestre, "GBT Formulation to Analyze the Buckling Behaviour of Thin-Walled Members with Arbitrarily Branched Open Cross-Sections", Thin-Walled Structures, 44, 20-38, 2006. doi:10.1016/j.tws.2005.09.005

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