The Direct Strength Method of design of cold-formed sections has been extended in the North American Specifiction for Cold-formed Steel Structural Members - NAS S100:2012 to include shear. The two new features of the DSM rules for shear researched are the effect of full-section shear buckling as opposed to web-only shear buckling and Tension Field Action (TFA). The prequalified sections in the rules include sections with flat webs and webs with small intermediate longitudinal stiffeners. In order to extend the range to larger intermediate stiffeners as occurs in practice, a series of 14 shear test have been performed at the University of Sydney for C-sections with rectangluar stiffeners of varying sizes.
University of Sydney School of Civil Engineering Research Report R950, April 2014, by Bruneau, Pham and Hancock.