Resonance - foundation of wind turbine tower

[Anonymous]

Hi everyone!

I would like to know if it's possible to analyse in Robot if the foundation of wind turbin tower won't avoid resonance with the wind turbine?

I was trying to do some simple tests (foundation plate) in modal analysis - but I'm not sure if it's good way? I have some results, but I don't know if the natural frequency of foundation plate on elastic springs  should change if I change Kz of soil? In my example there's no change in results.

Maybe it should be some dumper model for soil?

Thanks in advance.

[t.sautierr]

Post your file please.

[Anonymous]

I have attached the file.

Regards

[Anonymous]

Sorry for my English...
In first topic it should be "damper" not "dumper" 🙂

[t.sautierr · Accepted solution]

Your file contains only the plate.

If you want to analyse the resonance of the supporting structure of the turbine, you shall first analyse the supporting structure.

So :

Step one : put the supporting structure of your turbine (no need to add the slab)

Step 2 : make a modal analysis and look at the relevant modes

Step 3 : look at the frequency of the turbine and  look at the ratio F turbine / F structure -> come back to us.

About the foundation, I would be very surprised that you can have interaction between the turbine and a 2.5m raft ... : the frequency of your turbine will be high, and the one of the foundation will be governed by the soil -> much lower that a machine for most of the soils.

[Anonymous]

Thank you for your reply.

It's not real project, I was just testing if it's possible to do it in Robot. I don't have any technical information about wind turbine that I can compare with.
 
Someone told me, that this kind of problem can happen in wind turbine support structure (checking also with foundation plate) and it's necessary to check it.

But you are right, this problem probably shouldn't exist in typical situations.

[t.sautierr]

If you want to test then, you shall add spring support instead of elastic soil. 

Ask R.Gaweda or P.Pulak from autodesk but I'm sure elastic soil can be taken into account in a modal analysis.

I you want to see the response thehn : Time History Analysis -> do it with fiwed support and then with sping support, you will see I you have got an amplification.

[Artur.Kosakowski]

If you want to test then, you shall add spring support instead of elastic soil. 

Ask R.Gaweda or P.Pulak from autodesk but I'm sure elastic soil can be taken into account in a modal analysis.

Yes, elastic soil or support definition can be used for modal analysis however you shouldn't define them with uplift. 

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