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Robot Structural Analysis

Active Member
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Registered: ‎10-10-2012

Flat Slabs

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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?




Thank you ...



Product Support
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Registered: ‎12-17-2010

Re: Flat Slabs

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






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.

Artur Kosakowski
Active Contributor
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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 

Active Member
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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