Model of a stiff core

[Anonymous]

Hello,

I have built a shell model of a core and some extra walls that is standing on piles. When checking deflection due to wind, the values obtained are quite low.

I wonder if I have created some stiffness between the floors and the walls even though I have placed releases on those edges. (I am interested in the stability in the x-direction. I reduced the thickness of the slabs to 40mm and the deflection is still very low /around 17mm). 

Can you please take a look at the model and let me know if I have missed something.

Thank you in advance,

/Rita

[Rafacascudo · Accepted solution]

In fact , in the central area ,you released the wall edges , not the slab ones.

So , I moved those releases to the central slab edges  , but the X displacement remained around 17mm.

So I added a in-plane shear release for the slab and then the X displacements went to 31.3mm.

Then I noticed that not all contact edges slab-wall were released because some were not divided for this to occur.

So ,if it X displacement is still not enough , you can divide(use the "divide" edit option , it also divides edges) all remaing contact edges with the walls and apply the same release and the displacement will probably increase a little more.

But are you sure about a 40mm concrete slab??

[mustafahesenow]

Hi @Anonymous

In times of checking and designing for lateral load resisting system you can only reduce the inertia of walls and columns and beams slabs .

and you dont need to reduce the stiffness by releases if its not exist. 

You structural system is very stiff for only 5 stories and wind load only 1.3 Kpa so its normal to have small displacement .

So what that means your building is over design and you need to reduce wall length and you may add columns instead of wall 

and there is something not logic in the model first the raft slab which connected between piles and walls above in not correct to be 40 mm should be more bigger and even the slabs above.

Note when you add more release on slab you will get more displacement in one side and the other one still almost the same which mean that 

you increase the torsion effect on the building and this is may cause more problems.

[Artur.Kosakowski]

Hi @Anonymous

I just wanted to ask if the suggestions posted by @mustafahesenow and @Rafacascudo (thank you both) answered your question. If yes, would you mind marking them as the solution so that they are easier to find by others? Thank you.

[Anonymous]

The 40mmm slab was a test to make sure that The plates where not creating a lot of stiffness, but you were right, it was the releases. Thank you for your help!