American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

Alternative Title

Research Report RP15-1


With the proposed reorganization of the AISI S100 Standard, the Direct Strength Method (DSM) will take a position of equal footing with the Equivalent Width Method (EWM) for calculating strength. The majority of previous DSM studies focus 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) 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. We have included graphical representations of the relationships for DSM strength to the EWM strength ratio vs. material width to thickness ratio. While we are not exactly sure what the relationships mean yet, DSM strength seems to suffer vs. EWM strength for sections with relatively wide and thin compression flanges or in other words, large b/t ratios.


Civil, Architectural and Environmental Engineering

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures


American Iron and Steel Institute

Publication Date

01 Jan 2015

Document Version

Final Version


© 2015 American Iron and Steel Institute, All rights reserved.

Document Type

Technical Report

File Type