Dear Jason
Thank you for the clarification regarding the RNA mass. It has resolved my confusion.
My second question seems to be answered in a couple of previous posts of yours, Tower fore-aft modes shapes. sorry for not looking it up earlier. How can i use it in a FE model? What inertia values and references axes would i be using?
Please allow me to simplify my third question:
As FAST accounts for the mass and inertial effects of the RNA, if i were to use 6-component time series loads (from FAST) at the tower-top, i must eliminate the point mass and inertia from the FE model, otherwise, the loads would be double-booked. I hope my understanding is correct. However, if i were to use only the equivalent (resultant) or time-averaged static values of FA shear YawBrFxp and FA bending moment YawBrMyp at the tower-top, would I still have to account for the RNA mass, as i am ignoring the vertical forces from the FAST output?
Sincerely
Abhinav