Subdyn modifications

Dear Sir,

How can I alter the SubDyn code in FAST v8 to include the following additional force at every time step for the nodes at the pile bottom?

F_ext(t) = cxdot(t) + kx(t)


Dear @Kashyap.Subham,

A few comments:

  • The ability to add a linear stiffness matrix at reaction joints was added in SubDyn within OpenFAST, so, I recommend upgrading from FAST v8 to OpenFAST. This will give you the F_ext(t) = K*x(t) term.
  • Due to the Craig-Bampton reduction employed within SubDyn, damping is modeled via modal damping rather than as discrete damping elements at nodes. So, the F_ext(t) = C*x(t) term would not be feasible to add to SubDyn.
  • We are introducing a new module in OpenFAST called SoilDyn ( that allows more direct consideration of soil-structure interaction, including direct consideration of damping and nonlinear effects. This is another reason to upgrade to OpenFAST.

Best regards,