What Are Cold Formed Steel Shapes?

A wide variety of shapes can be produced by cold-forming and manufacturers have developed a wide range of products to meet specific applications. Figure 3.11 shows the common shapes of typical cold-formed steel framing members. Figure 3.12 shows common shapes for profiled sheets and trays used for roofing and wall cladding and for load bearing deck panels.

For common applications, such as structural studs, industry organizations, such as the Steel Framing Alliance (SFA) and the Steel Stud Manufacturers Association (SSMA) have developed standard shapes and nomenclature to promote uniformity of product availability across the industry. Figure 3.11 shows the generic shapes covered by the Universal Designator System.

The designator consists of four sequential codes. The first code is a three or four-digit number indicating the member web depth in 1/100 inches. The second is a single letter indicating the type of member, as follows:

framing member with stiffening lips
L = Angle or L-header
F = Furring channels
U = Cold-rolled channel
T = Track section

The third is a three-digit numeral indication flange width in 1/100 inches followed by a dash. The fourth is a two or three-digit numeral indicating the base steel thickness in 1/1000 inch (mils). As an example, the designator system for a 6'', C-shape with 1-5/8'' (1.62'') flanges and made with 0.054'' thick steel is 600S162-54.

Special Design Considerations for Cold-Formed Steel
Structural design of cold-formed members is in many respects more challenging than the design of hot rolled, relatively thick, structural members. A primary difference is cold-formed members are more susceptible to buckling due to their limited thickness.

The fact that the yield strength of the steel is increased in the cold-forming process creates a dilemma for the designer. Ignoring the increased strength is conservative, but results in larger members, hence more costly, than is needed if the increased yield strength is considered.

Corrosion creates a greater percent loss of cross section than is the case for thick members. All cold-formed steel members are coated to protect steel from corrosion during the storage and transportation phases of construction as well as for the life of the product.

Because of its effectiveness, hot-dipped zinc galvanizing is most commonly used. Structural and non-structural framing members are required to have a minimum metallic coating that complies with ASTM A1003/A1003M, as follows:
■ structural members – G60 and
■ non-structural members G40 or equivalent minimum.

To prevent galvanic corrosion special care is needed to isolate the cold-formed members from dissimilar metals, such as copper. The design, manufacture and use of cold-formed steel framing is governed by standards that are developed and maintained by the American Iron and Steel Institute along with organizations such as ASTM, and referenced in the building codes.

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Sean Carter said...

I have recently been reading a lot about the cold forming process and it is pretty fascinating stuff, loving seeing advancements like this

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