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Abstract

INTRODUCTION Cold-formed steel sections are formed from thin steel sheets, of typical thickness 0.015-0.25 inches, by either production cold roll forming or by specialized press braking. As a result, it is possible to produce economically a variety of cross-sectional shapes, which have high strength-to-weight ratios. Some structural applications include primary and secondary load-carrying framing members, such as columns, purlins and wall studs; and shear diaphragms, such as floor and roof decks and wall panels (Yu [1973]). Their design is governed by the American Iron and Steel Institute (AISI) Specification [1980], which is unique because of its generality, e.g., no specific shape is presumed. The philosophy behind cold-formed steel structural members is illustrated with the following example, adopted from Seaburg [1981]. Suppose it is required to design a 10-foot column, of any shape, to support a given axial load. One solution would be to employ a 3/4-inch square mild steel bar. However, a subsequent analysis of this slender column would show that it would fail, by flexural buckling, at a load of only about 500 pounds. Alternately, this same bar could be rolled into a thin strip about 12 inches wide and, in turn, used as the column. In this case, the strip would buckle essentially under its own weight. On the other hand, if this strip is formed, or bent, into the shape, say, of a lipped channel, its load-carrying capacity would be increased by twenty times that of the original bar. This simple example illustrates. of course, that the structural efficiency of a section is dependent on the manner in which the available material is distributed, which is a basic property utilized in the design of cold-formed steel members. Equally important is that this property leads to the proportioning of very thin structural sections which are prone to local buckling of the individual plate elements, or portions of the section between bends. It is this latter area that the present investigation addresses.

Department(s)

Civil, Architectural and Environmental Engineering

Sponsor(s)

American Iron and Steel Institute

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures

Publication Date

01 Mar 1983

Document Version

Final Version

Document Type

Technical Report

File Type

text

Language(s)

English

Technical Report Number

Report No. 83-1

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