Problem with stress in floors

[Anonymous]

Hallo everybory...i am trying to create a model for practise as you can see in the first picture...the floors have thickness 0,15 m, have FE and analytical way of transfer loads. Futhermore floors have partial stiffening...The Loads are G=2 and Q=3 KPa

I notice that stress is not the exbectable because it should be bigger in the area that slab joins the beams...the beams theoretically must be supports for the slabs...but this is not happened and i am very confused...any idea????

[Rafacascudo · Accepted solution]

You are probably seeing results for middle layer. Goto Parameters tab and set the  layer you want to see the stresses

[Anonymous]

@Rafacascudo  thans for the answer i choose the upper and the stresses were displayed...but i have still few questions:

1) in the first picture i notice that the moment diagram from panel cuts is not as i expected... i think that the moment shouldn't be like that but it should be possitive and higher in the middle of the slab and negative but lower in the supports (beams). can you explain me if i am whong?

2)In the second picture  there is the same problem with the displacements, it should be higher in the centre of the slab...????? 

3)In third picture you can see a comparison between deformation and displacements and although deformation seems logical, displacements are still strange and in my opition not the expectable...

4)In the fourth picture can you explain me why the moments in the centre of the slab are still negative for lower layer? this area must be in tension so i think the moments should be positives...

i am trying to understand robot but as you can see i have some little problems down here... thanks for the help, aprecciate...

[Anonymous]

picture 4

[Rafacascudo]

can you send the model??

[Artur.Kosakowski]

Hi @Anonymous

Try to increase sizes / moment of inertia / apply offsets to the beams - my assumption is that they are nor rigid enough.

For the bending moment and the layer - mind that only sign of stresses depends on the layer. The bending moment diagram will always be the same.

If this doesn't answer your questions attach the model as already suggested by @Rafacascudo (thank you for your help). 

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

@Artur.Kosakowski  maybe you are right about the rigity of the beams, i am also thinking about it, but on the other hand the seismic design according to eurocodes forced us to reduse the moment of inertia in the beams (assuption of cracking)...another assuption is the rigidy of slab  but has only 0,15 m height...i will attach the model (is very simple model) and if you find some spear time check it, aprecciate @Artur.Kosakowski and @Rafacascudo...

[Rafacascudo · Accepted solution]

You were seeing moments across the cut. Right setting for both cuts at once is choosing " local direction of the cut" and Myy . Then panel cut will show bending moment along the cut.

Also , You cannot set load distribution on panel calculation model , as triangular/trapezoidal method . If you want slab results ,than it has to be analytical. Setting all that ,you get the results below

Negative moment due to beam torsion stiffness. If you release slab edges for rotation , then you will get the moment diagram you imagined

 All the results you posted were compromised because of the Load distribution option you´ve made . Changing it to analytical will correct it all along with the linear releases

 corrected model attached

[Anonymous]

Thanks a lot i will check it...