Advances in the Direct Strength Method of cold-formed steel design

Twenty years ago, the Direct Strength Method (DSM) was first proposed as an efficient alternative to traditional design methods for thin-walled cold-formed steel (CFS) structural members. DSM may be regarded as one implementation of a class of generalized slenderness methods that are used in structural design. The objective of this paper is to provide additional context on how DSM-based design fits within past design knowledge and summarize the current state of development and future potential of the approach. Although DSM is regarded as a relatively new member design approach, its fundamental principles have long been used to explore relationships between stability, material yielding, and strength. The first ten years of DSM development (1998-2008) focused largely on simple prismatic CFS members under single actions and was conducted by a small group of researchers. In the last ten years of DSM development both the scope of DSM-based solutions and the researchers who are contributing to this development have broadly expanded. Since 2008 significant advances in DSM have occurred in strength prediction in shear, torsion, and combined loading; DSM efforts have also addressed buckling mode interactions, built-up members, elevated temperatures, member optimization, stiffness and ductility predictions, system-level implementations and more. DSM's ability to directly integrate elastic buckling simulation and provide efficient structural predictions for complex folded cross-sections remains one of its central advantages. Looking to the future DSM is well positioned to provide useful and efficient structural predictions and current efforts will continue to expand the scope and applicability of DSM.