These tests investigated the structural capacity and performance of built-up header assembly configurations typically used in cold-formed steel framing. The configuration of the header assembly was limited to doubled, back-to-back C-sections assembled in accordance with the Prescriptive Method for Residential Cold-Formed Steel Framing.
Currently, allowable spans of header assemblies are typically determined by doubling the allowable capacity of a single C-section (one of the two-member built-up header assembly), as calculated in accordance with the Specification for the Design of Cold-Formed Steel Structural Members. This conservative assumption and simplified design approach underestimates the actual performance of the header assembly, resulting in an uneconomical design and unnecessarily short header spans, particularly with thin deep sections. The findings of these tests demonstrated that greater header spans are possible with improved design rules.
Prepared for:
The U.S. Department of Housing and Urban Development
Office of Policy Development and Research
The American Iron and Steel Institute
and the National Association of Home Builders
August 1997, 23 pages