The newest version of RAM SS 15.05 now has unique stiffness modification factors for each deck direction for materials such as corrugated roof deck. However, I haven't found diagram, or example explaining what the factors "f11", "f22", "f12", "m11", "m22", and "m12" are actually referencing. I'm guessing these are possibly the in-plane and out-of-plane stiffness of the diaphragm? Will there be a tutorial soon on the best way to determine these for products such as Vulcraft b-deck for example?
The RamFrameAnalysis.pdf manual has details on these factors. I've included section 6.24 from the version 15.05 manual below, but the formatting is better in the original pdf.
Allen Adams will be presenting another webinar on "Diaphragm Design in Modern Structures" in the fall, so watch the RAM News Feed or our Announcements Forum for details about that. Here's a link to the Q&A from his last one.