Slab results comparison

[mar2805]

Guys I have a question on slab forces.
I made 2 egsamples of the same slab with the same load cases. Only difference is that the slab on the left is supported on 20 cm thick walls and slab on the right is supported on beams that are supported on columns.
If you look a the pictures for the Mx and My moment diagrams you can clearly see the diference in the values.
The results of the slab with beams are clear to me. Where the internal beams meet the section is very stiff, so the momets are greater (-8,30kNm/m for the Mx and -27,80 kNm/m for the My)
As we move thowards the mid of the span the moment decreases since the slab and beam will deform and because of that it will attract smaller forces.
Now please look the egsmaple on the left, slab supported on walls. Why are maximum moment in the slab at the mid span of the walls and not in the intersection of the walls? (My max=-13,70kNm/m) I dont get this?! Shoudnt this be the same case as with beams?! The maximum negative moments at intersection of the walls?!

http://files.engineering.com/getfile.aspx?folder=70109887-a03b-42ed-9d92-3bf330f956f6&file=Mx.jpg

http://files.engineering.com/getfile.aspx?folder=e52b4d5d-1497-47b9-a2b1-454de52fce87&file=My.jpg

 

[rowingengineer]

1. your statement stands.

2. I would distribute these moments using the flange width of your t-beam.

3. I'm not up to scratch with your code, but the clause in EN 1992-1-1:2004 (E), would be 6.3.2 I think. might be worth your while posting this in the structures forum. here is another discussion that was had in regards to the stiffness post cracking of a beam. thread507-247903

I would recommend design of reinforced concrete by Mosley. however I am an Australian engineer, and i found this useful when trying to design to your code, after i had a full understanding of concrete in Australian texts.

Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it