Slab Design with a User Defined Material

[luzer333]

Hello,

I'm trying to design a slab using fiber cement board which I defined earlier in the software, supported by steel beams. Please take a look at the attachment. I have two questions:

- Which Geometry should I use?

  Geometry Menu>Panels>Model (Shell or Slab-Rigid Diaphram, the steel beams are supported on every end so I see no use of using rigid diaphram, is there a difference between shell and slab in this case?)

  or

  Geometry Menu>Floors and the same model.

I guess both (Floor and Panels) come to the same end in this situation, right?

- Is there an easy way to check whether the internal forces exceed the strength of the material (like the Steel Design Menu)? If not, which parameter should I look at in the Results - maps Menu, Stresses - s, Shear Stresses - t, Shear forces - Q? I got the values of bending strength, bending elastic modulus, compression and tension strengths from the manufacturer.

Thanks

[t.sautierr]

Geometry Menu>Panels>Model (Shell or Slab-Rigid Diaphram, the steel beams are supported on every end so I see no use of using rigid diaphram, is there a difference between shell and slab in this case?)

Depends what behavior and results you want to model : 

does your pannel resist to lateral loads? Is it rigid enough to be considerer undeformable? -> this answer to the question diaphragm or not

do you want to analyse effort in the pannels? -> FE have to be activated if you want to

don't mix shell and slab : in robot shell means you will have FE in your pannels, slab is a set of parameters for pannel (can include shell 🙂 for example slab - flexible diaphragm)

  Geometry Menu>Floors and the same model.

See help, floors is a geometrical definition for a set of element, nothing to do with model or calcs

- Is there an easy way to check whether the internal forces exceed the strength of the material (like the Steel Design Menu)? If not, which parameter should I look at in the Results - maps Menu, Stresses - s, Shear Stresses - t, Shear forces - Q? I got the values of bending strength, bending elastic modulus, compression and tension strengths from the manufacturer

Depends what you have to check ! -> design code for this type of element. I don't know precisely what is the role of your element, but I would say check at least deflection and stress.

[Rafal.Gaweda]

IF you want to design it - use Shell.
The rest - as Thomas wrote Above.

[luzer333]

I used shell and FE mesh to analyse the fiber cement board. There is no mention about this material in the European or American codes, as far as I know. So I have to find a way to compare the given strengths with the internal forces. Can I compare the bending strength of the material with values found from Result - maps > Detailed > Stresses - s ? Or should I compare tension/compression strength with the "stress - s" value found in the lower layer (in parameters)?

[luzer333]

I decided to use bending strength compared with stresses - s. However there is 20% difference when I use the bending strength formula used in EN 310 (Determination of modulus of elasticity in bending and of bending strength) to derive the force applied. Any comments?