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Active Member
2much4any1
Posts: 7
Registered: ‎10-10-2012

Flat Slabs

1268 Views, 3 Replies
10-10-2012 06:55 AM

I'm trying to design flat slab, but diagrams of internal forces (M,T,N) seem to be wrong.

It's been used the following:

 - rigid nodal supports instead of columns,

 - mesh element size is 0,2m,

 - gravity load 5,0kN/m2,

 - span 5,0m (both directions)

 - slab thickness 200mm

 

Near edge support there is a unusual moment diagram.

 

How can I get "real" values for design?

 

Document2.jpg

 

Thank you ...

 

 

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Product Support
Artur.Kosakowski
Posts: 5,057
Registered: ‎12-17-2010

Re: Flat Slabs

10-10-2012 07:00 AM in reply to: 2much4any1

 

http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-E4E8BE33-DCD2-4343-824C-447A1AB5ECA0.htm?highl...

 

reduction.PNG

 

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Artur Kosakowski
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Active Contributor
rsousa_
Posts: 35
Registered: ‎05-23-2012

Re: Flat Slabs

10-10-2012 09:32 AM in reply to: 2much4any1

I think it would be usefull if you read annex I of EN 1992-1-1, that deals with Analysis of flat slabs and shear walls.

In elastic analysis (what you are doing in ROBOT), the negative moments tend to concentrate in the centre of columns.

 

For design purpose, you should get total moments and then divide between the strips... (or make panel cuts in those strips and get the integral value, that gives the total elastic moment in that strip)...

 

in my opinion, you shouldn't design with the diagram you showed, because it will give an unrealistic steel arrangement.

 

Best regards 

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Active Member
2much4any1
Posts: 7
Registered: ‎10-10-2012

Re: Flat Slabs

10-11-2012 12:01 AM in reply to: 2much4any1

Thank you for replies..

Yes, I know that I can't use those moments and that I have to divide into strips, but exactly how get design value?
That's the question..
I'm trying to do one example from the book according DIN 1045-1 but I can't get book values.

 

DIN 1045-1 Beispiele zur Bemessung Band-1 Hochbau.jpg

 

Bab87 Tom 2-prilozi.jpg

 

2.jpg

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