Page 389 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch09.qxd 9/29/05 5:25 PM Page 9.1

Source: STRUCTURAL STEEL DESIGNER'S HANDBOOK

CHAPTER 9

COLD-FORMED STEEL DESIGN

Roger L. Brockenbrough, P.E.
President
R. L. Brockenbrough & Associates, Inc.
Pittsburgh, Pennsylvania
R. A. LaBoube, Ph.D., P.E.
Distinguished Teaching Professor
Department of Civil Engineering
University of Missouri
Rolla, Missouri

This chapter presents information on the design of structural members that are cold-formed to cross-
section shape from sheet steels. Cold-formed steel members include such products as purlins and
girts for the construction of metal buildings, studs and joists for light commercial and residential
construction, supports for curtain wall systems, formed deck for the construction of floors and roofs,
standing seam roof systems, and a myriad of other products. These products have enjoyed significant
growth in recent years and are frequently utilized in some shape or form in many projects today.
Attributes such as strength, light weight, versatility, noncombustibility, and ease of production make
them cost-effective in many applications. Figure 9.1 shows cross sections of typical products.

9.1 DESIGN SPECIFICATIONS AND MATERIALS

Cold-formed members for most applications are designed in accordance with the North American
Specification for the Design of Cold-Formed Steel Structural Members, 2001, a consensus document
used throughout Canada, Mexico, and the United States. In the United States it is published by the
American Iron and Steel Institute, Washington, D.C., and referred to herein as the AISI North American
Specification (AISI NAS). (See also Supplement No. 1, 2004.) In Canada the document is published
by the Canadian Standards Association as Standard S136. The technical design provisions for the
three countries are similar, except for a few cases covered in Apps. A, B, and C of the document. The
AISI NAS applies to members cold-formed to shape from carbon or low-alloy steel sheet, strip, plate,
or bar, not more than 1 in thick, used for load-carrying purposes in buildings. With appropriate
allowances, it can be used for other applications as well. The vast majority of applications are in a
thickness range from about 0.014 to 0.25 in.
The design information presented in this chapter is based on the AISI NAS and its Commentary.
The design equations are written in dimensionless form, except as noted, so that any consistent sys-
tem of units can be used. A synopsis of key design provisions is given in this chapter, but reference
should be made to the complete Specification and commentary for a more complete understanding.
9.1
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