Floor Diaphragm, Composite Deck and Plate elementhttps://communities.bentley.com/products/ram-staad/f/ram-staad-forum/107498/floor-diaphragm-composite-deck-and-plate-element1. Does STAAD.Pro consider the Floor Diaphragm Action (transfer of lateral forces to the columns) when the Composite Deck feature is applied? 2. Considering the Floor Diaphragm Action, can i use plate elements instead of Master/Slave or Floor Diaphragmen-USTelligent Community 12RE: Floor Diaphragm, Composite Deck and Plate elementhttps://communities.bentley.com/thread/325651?ContentTypeID=1Fri, 29 May 2015 01:48:53 GMT6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:5cf68c54-b261-4392-92f2-7e9ad6014b4fSye1. The Composite Deck defines the beams as composite sections with the software calculating the effective width of the concrete slab when computing the composite properties for each beam. This way the stiffness due to the slab is accounted for. However it does not have the true effect of the diaphragm as there is no real connection in between these individual composite beams through the deck. <br /> <br /> 2. Yes you can.<div style="clear:both;"></div>