The North American Standard for Cold-Formed Steel Framing-Header Design, AISI S212-07, provides design expressions for cold-formed steel L-headers. However, methods to evaluate deflection of single or double L-headers and uplift flexural strength of single L-headers are currently not addressed. Presented in this report are the findings from an extensive testing program conducted at the University of Warteloo of full-scale single and double cold-formed steel L-headers. Also presented are improved ultimate flexural strength design expressions and new vertical deflection expressions and new vertical deflection expressions for single and double L-header assemblies.

It is anticipated that the AISI committee on Framing Standards will consider the results of this study in the development of future standards and the Cold-Formed Steel engineers Institute in the development of design aids. The American iron and Steel Institute and Steel Framing Alliance wish to express their appreciation to the researchers and project sponsors for this report.