5.2 DESIGN OF COLD-FORMED FRAMING

As mentioned in Chap. 2, the main design standard for cold-formed framing is Specification for the Design of Cold-Formed Steel Structural Members by American Iron and Steel Institute (AISI).1 The Specification, Commentary, Design Examples, and other information constitute the AISI Manual2 The first edition of the Specification appeared in 1946, with subsequent editions following in 1960, 1968, 1980, 1986, 1989 (by Addendum), 1996, 1999, and 2000 (the last two by Supplement). The LRFD-based Specification was first issued in 1991.3

In 2002, the title was changed to North American Specification for the Design of Cold-Formed Structural Members,4 to reflect the fact that many of the Specification s provisions apply not only to the United States, but also to Canada and Mexico. The provisions common to all three countries are included in the main body of the document; the country-specific items are placed in the Appendix. The users of the 2002 Specification have a choice of ASD, LRFD, and LSD Limit States Design formats. (The LSD design approach is widely used outside the United States.) As can be imagined, the combined Specification does not look any simpler than its notoriously complex predecessors.

The changes between various editions are substantial, a fact that reflects on the continuing research in this area of steel design. Since the Specification provisions are so fluid, framing manufacturers are challenged to comply with the latest requirements. Unfortunately, some have fallen behind, still using the previous editions.

Anyone who has ever attempted to design a light-gage...