Modeling RC flat slabs using plate elements

[tonycampos88]

I am trying to design a RC flat plate simply supported on concrete walls. My question is how would you advise me to model these supports?

Right now I just have my slab supported on pins at every node where I know there is a bearing wall. The problem that I am having with this approach is when I check shear, as I have several stress concentrations and singularities in my elements near my supports and (as I lack experience in doing this) I don’t know which stress concentrations I should just ignore and which ones I should be careful with (even if I average the shear forces using the contour display tool). Also, I get very high concentrated reactions at the pin supports (either in compression or in uplift).

I was thinking to model these supports with a rigid beam element, but then the beam would take some moment and the slab would be fixed at that location. Do you have any suggestions?

 

[structSU10]

a finer mesh, and using a vertical spring support, may help to alleviate stress concentrations a bit.

 

[JedClampett]

There needs to be an element of common sense when evaluating these models. If it's simply supported rectangular plate, the highest shears will be in the middle of the spans, where the plate tends to act in one way action. Sometimes there is a reversal of shear in the corners, as they try to physically rise up. this might result in some weird local stresses, but they shouldn't exceed the midspan ones.
Anyway, if any of your shears exceed a simply spanning beam load, you've got a stress concentration that you need to explain away.

 

[rowingengineer]

If you model the walls as fixed pins, these will form couples with high tension and compression. The magnitude will be dependent on the distance between the nodes. I would consider changing you pin supports to springs or full wall models.

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