Hi all,
I am at a total loss on how to properly model a flexible metal deck diaphragm in RAM Elements 14.0. My understanding from reading other posts on this topic is that using shell elements are a bad idea (I can link these posts if desired). Using area loads also doesn't work because I need to essentially have all the nodes on my roof level to behave as if they are restrained from the diaphragm, and area loads only give me a way to apply roof dead/live load.
To clarify, I do not want/need RAM to design my diaphragm for me. That is easy enough by hand and makes things complicated. I just want to model my structure such that when I apply, for example, a uniformly distributed LATERAL load to the roof beams of my structure, that the load will not bend those beams about their weak axis, but instead transfer that load over to my collecting elements as distributed axial load (diaphragm shear).
If this is not possible, then what is the easiest alternative to achieve a similar result? How do other engineers work around this?
You can assign a rigid diaphragm constraint which are called floor diaphragms in Ram Elements in the nodes tab of the spreadsheet.
If flexibility of the diaphragm is critical then using thin shells is a possibility (with some side effects to consider), or simulate the diaphragm with a few diagonal braces in the deck plane.
Any suggestions for when the diaphragm is sloping? I have the same issue of wanting to apply a lateral load to the perimeter beams, but my roof slopes, and Elements won't allow different elevations for nodes in a rigid diaphragm. If I model the roof as flat at the max roof height, my braces on the low end overstress in compression with the size brace I'd like to stay within. If I model it flat at the low height everything works, so I can envelope it that way, but is there a better way in that case? Translate my wind loads to nodal loads instead distributed loads?