Application of the Direct Strength Method to Steel Deck

With the reorganization of the AISI S100 Standard, the Direct Strength Method (DSM) takes a position of equal footing with the Equivalent Width Method (EWM) for calculating the strength of cold-formed steel cross sections. The majority of previous DSM studies focused on C and Z profiles, while little study of panel sections, especially steel deck sections, has been performed. A study was undertaken to determine and compare the behavior and usable strength of existing floor and roof deck sections with both DSM and EWM. The Cornell University – Finite Strip Method (CUFSM) software was used for the elastic buckling analysis, taking into account the wide, continuous nature of installed deck sections. Flexural capacity was analyzed for positive and negative flexure to account for gravity loading as well as uplift of the steel deck sections. Graphical representations of the relationships for DSM strength to the EWM strength ratio vs. material width to thickness ratio were developed and are illustrative as to the trends seen. DSM predicts lower flexural strength versus EWM for sections with relatively wide and thin compression flanges (larger b/t ratios)

Direct Strength Method for Steel Deck

The American Iron and Steel Institute (AISI) Standards Council selected this project as one of four winning research proposals for its 2014 Small Project Fellowship Program. Projectselections were based on several factors, including the potential for long-term impact on the industry; steel industry engagement and co-funding; and results for the AISI standards development committee, the student, and the academic institution. The objective of this project was to determine and compare the behavior and usable strength of existing floor and roof deck sections with both the Direct Strength Method (DSM) and Effective Width Method (EWM). It is anticipated that the results of this study will guide future research and development efforts