Slab long term deflection - creep and shrinkage

[hiep]

Hello,

In on of my projects, I will need to check slab edge deflection at long term to ensure no detrimental effects on the cladding.

I know that Robot can do cracked deflection, but I was wondering if Robot could calculate slab long term deflection including creep and shrinkage? 

I could not find any guidance on this. Could I get some advice?

Thanks,

[Artur.Kosakowski]

Creep is taken into account (see the attached picture) but there are no parameters for shrinkage in the RC Slab Required Reinforcement module. You may try to include this effect by definingtemperature load applied to a panel. 

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[Rafal.Gaweda]

Additionally please check this thread:
http://forums.autodesk.com/t5/robot-structural-analysis/can-robot-do-all-these-checks-when-designing...

[hiep]

Thanks Artur,
I seems you haven't attached the picture you refer to?

[Artur.Kosakowski]

I'm sorry. The missing picture.

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[Mohammed_Ata]

How can we show the long-term deflection diagram ? Its button is always deactivated !

[Artur.Kosakowski]

Could you attach the screen capture that shows which button you mean please? PLease include the whole Robot window rather than just a small part so that I could understand which option we are discussing. Thank you.

[hiep]

Artur, 

Thanks for this, we understand the process, for inputting a creep factor in this box, there is a further one within 'RC Design' relating to storey parameteres.

The Creep coefficient within here is greyed, unaltered and appears inconsistant to the factor defined in the first 'materials' box.

What is the link between this and the design and how do we check what creep factor is being used. 

[Artur.Kosakowski]

Slab reinforcement calculations are based on the parameters assigned in the reinforcement type assigned to a panel. What is done in the Slab Provided reinforcement module is the distribution of reinforcement based on already calculated required area of reinforcement. Mind that in fact you may even not use the Slab Provided Reinforcement module at all e.g. in situation when you make distribution of reinfiorcement in program such as e.g. ASD Reinforcement.

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[hiep]

Thanks Atur,

I will use the properties in the panel definition for long term deflection analysis. 

Just to better understand the Story Parameters in the Provided Reinforcement, could you give us more information on your statement "What is done in the Slab Provided reinforcement module is the distribution of reinforcement based on already calculated required area of reinforcement".

Is there any guidance for this? I would like to know when it should be used. The creep factor appears to be fixed to 2.5 which is a bit strange. 

Many Thanks,

Hiep

[Artur.Kosakowski]

To keep it simple: imagine that you want to calculate required area of reinforcement by hand. You assume cover, arm of forces, creep, steel and concrete grade etc. and you get theoretical area of reinforcement. This is what is done in the RC Slab Required Reinforcement module. Then you want to produce the reinforcement arrangement drawing so you select bar diameter and knowing the required area you decide on bar spacing. This is the RC Slab Provided Reinforcement module task (plus verification of punching).

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[aokuns]

How can one calculate the long term deflection and show its diagram? It appears deactivated and greyed out always.

[Artur.Kosakowski]

Please watch the recording of the 5th Robot webinar available from:

http://forums.autodesk.com/t5/robot-structural-analysis-forum/robot-structural-analysis-webinars/td-...

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[aimanalaawar]

Dear @Artur.Kosakowski, is this in the attached picture the long term deflection?

[Artur.Kosakowski]

Hi @aimanalaawar

Correct.

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[aimanalaawar]

Hi @Artur.Kosakowski

If I want the long term deflection for dead load and 30% sustained live load should I define a load combination with (1 DL + 0.3 LL) or I should set the Ratio of Loads: long-term to variable: to 0.3 when defining the reinforcement pattern

Thank you

[Artur.Kosakowski]

Hi @aimanalaawar

Assuming that 0.3 LL in the definition of the combination stands for the sustained part of 100% LL then for this particular combination you shouldn't reduce it further so the ratio of Loads: long-term to variable: should be 1.

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[aimanalaawar]

Thank you very much @Artur.Kosakowski

[maximeXNZTH]

Hi Artur,

If I understand it correctly, it means reinforcement inserted along with the material properties (seen screenshot attached) are used for initial theoretical required reinforcement calculations. This has no influence when calculating long-term deflection in the Provided Reinforcement module. Am I correct to say this? Thanks in advance for your help.

Max

[Artur.Kosakowski]

Hi @maximeXNZTH

I'm not sure if I understand your question correctly but you can run (long term) deflection verification for the provided slab reinforcement.

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