Difference in diaphragms

[Anonymous]

Hello,

I've been doing research on the definiton of flexible diaphragm and have found that it should transfer forces to resisting structures according to tributary area. Rigid diaphragm should transfer forces according to the rigidity of the resisting structures.

I made a simple model and compared the results using these two diaphragms with horizontal load only. The above mentioned definitions do not seem to be true in RSA. You can see from the pictures that the results are almost identical. I would think that when the slab is a flexible diaphragm, the inner walls would have greater resistance than the outer walls. I am very confused and don't know what to believe anymore. Can someone please help me understand how these diaphragms work?

The whole structure in the picture is made of concrete and all supports are pinned.

Also if someone could provide guidance on what calculation model should be used  for the slab while calculating the rigidity of the construction under wind load, would be greatly appreciated.

[Μηχανικος]

Where can i find more information on meshing? for example whats the difference between Iterative adjustment of the FE mesh and Kinematic constraints in coherent points?

After posting this ive just remembered the first webinar by Artur "Meshing : how to set parameters and how to avoid problems" there is lots of informartion specific to my question

https://www.youtube.com/watch?v=xYMxOfl7N1c

[AhmedZA]

http://help.autodesk.com/view/RSAPRO/2016/ENU/?guid=GUID-787B583F-32DB-4F29-847A-DC7D803BEDB7

[Jummybear]

To be continued?

[pu.sun7DUEC]

Hi, @t.sautierr 

After seeing you post, I kept wondering what might be classified as Normal Thickness you described regarding Shell elements, did you mean the 150mm to 300mm slabs that we normally come cross in daily constructions.

Also, I understand that the modelling should reflect the reality, and the slabs on site e.g., simply supported slab, is meant to restrict relative movement within its diaphragm (or too small to count) but be flexible out-of-plane, you mentioned modelling slab as shell is the most complete way, I could quite grasp what do you mean by COMPLETE, can you please elaborate it a bit more, I really appreciate your time.

Regads

Ethan