Plastic and Lateral-Torsional Buckling Behavior of Single Cold-Formed Channels Connected Back-to-Back
Publication: Journal of Structural Engineering
Volume 132, Issue 8
Abstract
This paper describes the results of a series of experiments on semi-rigid and inelastic joints, and lateral-torsional buckling of the eaves region of portal frames comprising cold-formed single channels bolted back to back at the eaves and apex joints. The tests demonstrate the considerable ductility that is achieved in the back to back bolted connections, which should be sufficient in many cases to accommodate plastic analysis of the portal frames. Variables in the tests include the number of bolts in the connection, the lengths between lateral restraints, the width of the channel flanges, and the strength of the channels. Adjacent column and rafter channels are oriented successively in opposite transverse directions to take advantage of the counterbalancing moments and forces in the back to back connections. This system is important in enhancing the lateral buckling strength of the channels. An innovative method is proposed for connecting each purlin to the web of the column or rafter through a cold-formed angle. Experiments have shown this system to be capable of restraining the frames from failing due to lateral-torsional buckling. This eliminates the idea of having fly bracings, which is normally done in practice to restrain torsional instability.
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Acknowledgments
The writers wishes to thank the Southern Africa Institute of Steel Construction and THRIP for sponsoring this research, Robor and MacSteel for providing the materials, and Tass Engineering for cutting and drilling holes of all items used in this research.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 132 • Issue 8 • August 2006
Pages: 1223 - 1233
Copyright
© 2006 ASCE.
History
Received: Nov 29, 2004
Accepted: Oct 25, 2005
Published online: Aug 1, 2006
Published in print: Aug 2006
Notes
Note. Associate Editor: Donald W. White
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