Beam with shell

[adrian_ricinschi]

Hello,

I have a model with steel beams.

On the right side there is a concrete shell on top of the beams. On the left side there is a cladding.

The load is the same on both sides.

The  concrete has the moment of inertia reduced to 10%.

Can you tell me what could be the issue for the shape of the diagram on the right side?

[Rafacascudo]

hard to tell without the model

[Artur.Kosakowski]

Hi @adrian_ricinschi

The meshed panel transfers some load so the beam 'gets' less of it.  As the meshed slab and beam work together you got the negative moment die to the slab stiffness as it is continuous (applying the release at the beam end in such situation cannot make it too act as a simply supported one).

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[adrian_ricinschi]

I know that the shell will "take"some of the load.

The problem is that the moment goes at the upper part of the beam and then goes to zero which is not correct.

[Artur.Kosakowski]

Hi @adrian_ricinschi

"As the meshed slab and beam work together you got the negative moment die to the slab stiffness as it is continuous (applying the release at the beam end in such situation cannot make it too act as a simply supported one)".

Try to change the thickness of the slab to a very small (e.g. 1 mm) one.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Rafacascudo]

I was ready to agree with Artur about this problem but experimenting (always!!!) with a refined mesh(25cm instead of 50cm) did the job !!!

Now , I wonder why???

[Artur.Kosakowski]

Hi @Rafacascudo

Can I have both models?

[Rafacascudo]

Hi Artur

 @adrian_ricinschi sent me the model in private .

So I need his permission to send you directly

[adrian_ricinschi]

Yes, you can send both models.

Thank you!

[Artur.Kosakowski · Accepted solution]

Hi @adrian_ricinschi

The bending moments as visible on the picture you attached suggested that the slab was continuous but after looking at your model I noticed that you applied linear releases at both edges of the panels along the beam defined in the same direction so indeed the bending moments should look as for simply supported beams. The reason they weren't was that the release defined for panel 1038 was not actually created during the model generation (I don't know the answer on the why question )

If you generate the mesh for this panel again it is applied (therefore @Rafacascudo model with smaller mesh size 'worked').  I will send Rafael the corrected model with the same mesh as size as in your original one. 

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Anonymous]

Hi, I have a very similar issue but with Vertical Shear.

When I analyse my slab as Deck Slab One Way Spanning (0.01I Flexural Stiffness, 0.25E In Plane Stiffness), it appears to cause interaction between the Supporting Beams and Edge Beams, or Supporting Beam and Column Node. So that the Vertical Shear of my Supporting Beam reverses at the supports.

[Anonymous]

Update: If I model as Hollow core Slab and Tick "Disregard Stiffness in Transverse Bending" the problem goes away but this is a bit of an awkward work around considering I am modelling a Slab on Trapezoidal Metal Deck.