Perform a dynamic analysis of the jacket using CFD considering wave and current loading including vortex shedding

Thanks for your suggestion, but preferably I would like to find soms analytical formula's in order to get som physical insights

dear Kasiphon,

thanks very much for your info, I will use these numbers in the analyses

I hope that you already found a solution since it has been almost a year since your question. There are several well accepted software tools used in industry for marine structures (jackets). Depending on the site conditions there will be an interest for either wave - wind - current loading condition or seismic ground motion induced loads. From Kasiphon K comment you will see that soil induced damping if far higher than hydrodynamic. I believe today you can model fully "interconnected" jacket - foundation analysis with soil - structure interaction tools available through commercial software (SACS, Abaqus, etc).