topic Re: Slab Moments Problem in Robot Structural Analysis Forum

Slab Moments Problem

Anonymous — Sun, 28 Oct 2018 19:08:12 GMT

My English is not good, but I've got a question about the momets map in Robot, I need the map of the moments like this picture.

But the moments I get on the slab are these...

How can I solve this? Do I need to edit somethin on the slab or beams?

Re: Slab Moments Problem

EduardoMeruvia — Mon, 29 Oct 2018 00:54:09 GMT

Hi @Anonymous,

Try checking the 'LOCAL PANEL DIRECTION' or your shell elements. From the picture you posted about the moments you want to "achieve" it seems these moments are the moments in the Global spanning Direction of the X-Direction. See which LOCAL shell direction aligns with this and this should give you the moments you are after... i.e. might the case that this is the Moments in the yy direction in your model.

Hope this helps.

Re: Slab Moments Problem

Anonymous — Mon, 29 Oct 2018 01:18:15 GMT

I will try, in the end, I want to get this.

Re: Slab Moments Problem

EduardoMeruvia — Mon, 29 Oct 2018 03:09:12 GMT

@Anonymous,

Can you share your model here, I'll be happy to take a look at it.

Re: Slab Moments Problem

Anonymous — Mon, 29 Oct 2018 04:48:28 GMT

Of course, I'm a beginner, I need the moments on the slabs for its structural design, as the ACI asks. I send you a .RAR archive, I couldn't send the model.

Re: Slab Moments Problem

EduardoMeruvia — Mon, 29 Oct 2018 05:19:32 GMT

@Anonymous, from a quick look at your model, I don't see anything wrong with it. The results that the model show to seem correct and as you would expect. See figures below;30.5cm slab - Mx Results

30.5cm slab - My Results

However, if you are trying to account for the difference between your slab Bending Moments and the "Expected" bending moments as the picture you are trying to follow, it might be due the Slab Stiffness difference between the models. If you reduce yous slab thickness from 30.5cm to say 12cm, then the Bending Moment maps follow the shape of those bending moments you are trying to "achieve". See figures below, results below are based on a 12cm slab thickness.

12cm Slab - Mx Results12cm Slab - My results

Re: Slab Moments Problem

Anonymous — Mon, 29 Oct 2018 05:43:05 GMT

What a shame :s. The minimum thickness I calculated it with ln/33, how ACI asks. However, thank you for your help.

Re: Slab Moments Problem

Artur.Kosakowski — Mon, 29 Oct 2018 08:25:03 GMT

Hi @EduardoMeruvia

Thank you for your help for this topic. Much appreciated.