Hey everyone,

A discussion has been started in my office about the use of plates in a model and their uses.

Usually, I'll model a plate between each beam.  So, if I have a bay with 4 infill beams I have 5 plates.  Typically, I check the plane stress box when I put these plates in so lateral loads distribute if I put wind load as a line load along the floor lines.  

Would I get the same results if I put in a membrane diaphragm in the floor instead of plates?  

I'm curious to hear what other users do and why.  

Thanks for the input everyone!  

PLATE:  Resists out of plane loads only. (bending element)
MEMBRANE:  Resists in-plane loads only (diaphragm shears)
SHELL:  combination of plate and membrane.

 

The plane stress plate elements give you "membrane" behavior, but it is based on the stiffness of the plate elements.

The mesh, the plate thickness and plate material properties will all help to determin how rigid this diaphragm made out of plate elements will behave. I would refer to this as a stiffness based diaphragm solution.... though others may call it a "semi-rigid" or "semi-flexible" diaphragm.  

If, however, you use our "rigid membrane diaphragm" option rather than using plate elements, you will get completely rigid diagphram behavior out of your model.