Composite Steel/Concrete Deck

[Anonymous]

Hi,

I am modelling a steel frame with an RC core taking the horizontal loads. I want to transfer the horizontal loads to the core using a composite steel/concrete deck (1way spanning). I have used a partial stiffening in XY and input the geometry properties of my deck (without finite element).

I can see that the load is transfer to the core. Did I do it properly? Or shall I choose without stiffening?

If I choose withouth stiffening, Robot will use the stiffeness of my deck (based on my geometrical input)?

Thank you

[Artur.Kosakowski]

If you want to include the properties of the deck as you defined it you should select the finite element type shell for the elastic stiffness and then as you will have mesh generated there is IMHO no need for rigid links generation so you may also select without stiffening option. 

f I choose withouth stiffening, Robot will use the stiffeness of my deck (based on my geometrical input)?

Yes.

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[Anonymous]

Thank you Artur.

But, because I have already designed the deck under vertical load and I am only concerned about the its property of distributing the wind load, what do you suggest?

If I use a shell (with one way distribution) without stiffening, I have really low horizontal displacements for my steel columns.

If I use a plate without FE and without stiffening I have a lot of displacements and my steel portal frame at the edge of the building takes the moment due to wind.

Which one gives the right distribution of the horizontal load?

Thank you

[Artur.Kosakowski]

IMHO the bottom values are too large and they cannot be like this in a real structure. 

[Anonymous]

But if I have applied the same thickness (geometrical properties) to the plates and both are without stiffening, shouldn't I have the same floor stiffness?

Why the finite element is "absorbing" all the horizontal load and does not transfer it to the moment frame?

Is the shell suppose to act like that?

Thank you

[Artur.Kosakowski]

If you haven't meshed the panel and you decided against using the rigid links the floor has got no in-plane stiffness at all. It can only transfer vertical loads to supporting elements (including its self weight which can be calculated based in the assigned thickness) but is not a structural part of the model. 

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.

[Anonymous]

Thank you Artur.

On post 2 you confirmed that "if I choose without stiffness Robot calculates the stiffness based on the thickness properties". I thought that was regarding both FE and Panel without FE. But now I got that it is only for FE.

Can I ask also:

1) which one do you suggest for a more accurate horizontal load distribution? FE with thickness or plate with partial stiffness?

2) Am I right saying that the plate with partial stiffness could be more rigid than my actual deck and therefore may be optimistic?

3) If the panel without rigid links  "can only transfer vertical loads to supporting elements (including its self weight which can be calculated based in the assigned thickness) but is not a structural part of the model", the only difference between it and a cladding is that I can't apply a thickness (and self weight) to a cladding?

Thank you

[Artur.Kosakowski · Accepted solution]

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Franco.dipietro wrote:

Thank you Artur.

On post 2 you confirmed that "if I choose without stiffness Robot calculates the stiffness based on the thickness properties". I thought that was regarding both FE and Panel without FE. But now I got that it is only for FE.

" you should select the finite element type shell for the elastic stiffness and then as you will have mesh generated there is IMHO no need for rigid links generation" 

Can I ask also:

1) which one do you suggest for a more accurate horizontal load distribution? FE with thickness or plate with partial stiffness?

I think that correctly meshed panel will be more accurate.

2) Am I right saying that the plate with partial stiffness could be more rigid than my actual deck and therefore may be optimistic?

Rigid links will provide much larger horizontal stiffness of the deck.

3) If the panel without rigid links  "can only transfer vertical loads to supporting elements (including its self weight which can be calculated based in the assigned thickness) but is not a structural part of the model", the only difference between it and a cladding is that I can't apply a thickness (and self weight) to a cladding?

Correct. 

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.