Thank you very much Peter, it works, I merged the nodes !

I would like to take into account the fluid body now for modal to do transient & spectral analysis.

I added the water body in the model. I meshed it. I did modal.Do you think that the main structure modes are in high frequences?

How do you manage the damping? Structure damping (concrete 7%) and water 0,5%. Is it in modal analysis or in transient & spectral analysis?

I have an other question, how do you create residual mode when i can't get the 90% minimum of the mass after 33hz ?

Thank you.

Best regards