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# Risa 3d orthogonal plates

## Risa 3d orthogonal plates

(OP)
If I model an inverted L (end of small leg fully supported, end of longer leg laterally supported - loads down long leg) using plates I get very large deflections. The results point to rigid body movement or the plate formulation cannot handle this situation. Has anyone else had a similar experience with plates.

### RE: Risa 3d orthogonal plates

What sort of boundary conditions are you using? Plate elements are not capable of handling the "Drilling" degree of freedom.  So, if you are relying on this a means of support, you will get some problems (i.e. large deflections).

What sort of Mesh are you using? Whether or not the structure is properly meshed will largely determine the accuracy of the results.  A poorly meshed model can greatly exaggerate the drilling boundary condition issue I mentioned above.

### RE: Risa 3d orthogonal plates

(OP)
Hi
Thanks for your reply. I have square 20 mm x 20 mm x 3 mm thick elements with full translational fixity some distance removed from the orthogonal intersection so drilling will not be a problem. I found that if I make the elements larger 100 mm x 100 mm the problem of large deflections evaporates. Now I am curious if the formulation of the element has limitations on the size/thickness ration. The formulation is in Bathes book, which I own, so I may have to plow through the maths. Thanks again for your interexst.

### RE: Risa 3d orthogonal plates

Just a suggestion - shouldn't this be in the RISA 3D forum?
This is supposed to be the RISA Floor forum.

forum1419: RISA Technologies: RISA-3D

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