Instruction for the Seismic fast version

Wind & Water Computer-Aided Engineering Software Tools
22

Dear @Kashyap.Subham,

At one point we developed a customized version of FAST v7 that supported distributed springs (DS) modeling of the foundation. This is discussed in the following forum topic: Turbine-soil interaction. Influence on the mode shapes., especially my post dated Feb 01, 2013, where I share an example UserTwrLd_DS.f90 file.

This routine has not been developed to include seismic excitation, but should hopefully be a good start to that. Because I have not done what you want myself, I cannot provide detailed guidance, but to answer your specific questions:

  1. Agreed. The FAST v7 model that makes use of UserTwrLd_DS.f90 places the platform reference point at the bottom of the pile (where 6 DOF motion is available), and the entire pile + tower is modeled via the tower element in FAST v7.
  2. The UserTwrLd_DS.f90 file implements linear springs at each node along the pile, but this could be changed to model nonlinear springs.
  3. I would not expect to that you’d apply ground motion only at the base of pile. Rather, I would expect that the deflection of each spring distributed along the pile would be the difference between the actual deformation of the pile and the position defined by the seismic event.
  4. I’m not sure what you mean, but I would not expect that anything in the source code would need to be changed apart from the UserTwrLd_DS.f90 file.
  5. This will be done automatically by FAST v7. It is just up to you define the loads to be applied distributed along the pile in the UserTwrLd_DS.f90 file.

Best regards,