Strange Shape Concrete Surface

[jjsolly]

Hi. I am looking at potential reinforcement design for a strange-shaped wall and i am struggling to get the provided reinforcement in place. The steps I want to do are as follows:

1 - Linear Analysis (might need to be non-linear really due to geometric nonlinearity)

2 - Reinforcement design (not really too worried about this - guidance for the next step but i think i need to do it first)

3 - Define a heavy mat of reinforcement is required and then check both the deflections and stresses generated based on a cracked/non-linear analysis. 

I have attached my model. My main issue is that when i go to "Slab - provided reinforcement" there is actually nothing there at all i.e. no buttons are lit up and no model can be seen.

I'm assuming there is something obvious i'm missing. 

[Artur.Kosakowski]

The RC Slab Provided reinforcement module is capable of making reinforcement distribution in flat panels only. For the shape as you have got you can calculate required area of reinforcement but the distribution of rebars or wire fabrics has to be done 'outside' Robot.

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.

[jjsolly]

Thanks Artur. 

As i understand it, the RC module can take the required areas of reinforcement then can calculate the expected deflections based on that.

And i can, to a degree, vary this result by specifying whether to include minimum reinforcement or not. I can therefore get different areas of "required" reinforcement dependent on choices i make. 

So it seems like there should be a way for me to input that i'd like a value of 2262mm2/m in all directions as a minimum.

In fact - a crude way would be to simply be if i could modify the table of reinforcement per finite element and input my own values. Then run verification and see the results.

Is there really no way to do that? It appears that very nearly all the functionality is there! Is there a method through the API of defining the reinforcement per element prior to verification? 

Thanks 

[Artur.Kosakowski]

It is not possible to overwrite the values of reinforcement calculated by Robot and use them for kind of calculations. What you could try to do is:

1. Calculate required reinforcement with the minimal reinforcement set for the whole panel

1a. For some elements calculated area of reinforcement is smaller than 2262mm2/m create a dummy load (e.g. temperature) which would cause the 'need' for such areas

2. Run verification of deflection with stiffness update based on calculated area of required reinforcement.

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.

[jjsolly]

Good idea Artur. I can see how that would work.

To confirm i've understood correctly:

The "Verification of Deflection with Stiffness Update" only considers the stresses found from a previous run. It does not re-run the analysis model with cracked-sections.

I'm interested in understanding the effects of concrete cracking on the flexibility of a complex shell-structure and hence the load paths developed. i.e one region cracks and therefore becomes more flexible therefore the stiffest path is now in a new area of the structure.

I do not believe i can achieve this with Robot unless i do a "manual" iteration and update specific panel properties based on whether they have cracked in a previous analysis run.

Cheers,
James

[Artur.Kosakowski]

---

To confirm i've understood correctly:

The "Verification of Deflection with Stiffness Update" only considers the stresses found from a previous run. It does not re-run the analysis model with cracked-sections.

It updates the stiffness of surface elements of the panel(s) you are going to run the verification of deflections for replacing the 'elastic' material properties with reduced (cracked) stiffness calculated during reinforcement calculations and launches calculations of the model with such updated surface elements.

I'm interested in understanding the effects of concrete cracking on the flexibility of a complex shell-structure and hence the load paths developed. i.e one region cracks and therefore becomes more flexible therefore the stiffest path is now in a new area of the structure.

I do not believe i can achieve this with Robot unless i do a "manual" iteration and update specific panel properties based on whether they have cracked in a previous analysis run.

When you calculate reinforcement for panels in addition to maps of reinforcement you can display maps of 'reduced' stiffness too. Based on them you may create new panels on selection of surface elements and assign new material properties but this is going to be manual iteration. The 'stiffness update' deflection verification method just makes the first iteration.

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.