A question about the C-B modes obtained in SubDyn

A quick question about SubDyn.

When enabling CBMod, output files called ‘xxx.SD.CBmodes.json’ and ‘xxx.SD.sum.yaml’ are produced, through which it is possible to visualise (using this website) and read the natural frequencies of vibration for each mode.

My question is: when deriving these GY and CB frequencies, are the masses and moments of inertia of the tower and RNA included?

Many thanks

Dear @Maurizio.Collu,

The short answer is “no”.

The Guyan + Craig-Bampton reduction used within SubDyn is based only on the structural formulation within SubDyn, and does not include ElastoDyn, HydroDyn, etc. (and does not include tower and RNA, unless these are defined within the SubDyn model).

Best regards,

Thanks a lot @Jason.Jonkman for the clarification.

Kind regards