Bill,
It should be modeled as a rigid diaphragm.Depending on dimesions of the roof framing, corrugated metal roofing on steel trusses could also be modeled as ridig diaphragm.
Alex
----- Original Message -----From: William.Sherman@CH2M.comSent: Tuesday, October 09, 2007 3:27 AMSubject: 3D model with metal deck diaphragmWhen performing a 3-D structural analysis of a complex steel building with metal deck roof, how is the metal deck typically modeled (i.e., stiffness, load distribution, attachment to trusses, etc)?(I tried searching the archives but couldn't find much other than "why do you want to model a flexible diaphragm?")BillWilliam Sherman - CH2M HILL / DenverStructural Technology Discipline Leader (TeD)Engineering Design Group - Civil / Federal Engineering (EDG-CFE)720.286.2792