how I calculation the stiffness for input into CAESAR II

Dear all,
if I have vessel nozzle calculation result from FEA shell model, how I caculation the stiffness for input into piping model in CAESAR II (Vessel and Nozzle joint in Cnode)? is the following step correct?
from the nozzle vessel joint FEA result from each direction: Stiffness =(Nx/tx,Ny/ty,Nz/tz,Mx/ax,My/ay,Mz/az),in where Nx,Ny,Nz, Mx,My,Mz is force or momnet in joint point, tx,ty,tz,ax,ay,az is translation or rotation in joint point.
do I need multiply the related beam stifness in the above stiffness caulcation?
thank you for your comment and advice.
Best Regards

Modelling from centerline vessel to outside vessel a rigid element.
Take a Cnode at this position connected with the nozzle node.
FEA stiffness at Cnode and is ok.

very thanks to Mr. Ohliger
the stiffness calucation step is correct or not? do I need multiply rigid element stiffness?

I think is correct.
You must not multiply with rigid stiffness !
How you do your FE-Model (Vessel length bode site from the nozzle ?)
The best stiffness model in Caesar you become with additional rigid in vessel length with the same length as you have in your Fe-Model from nozzle centerline until your FE-Restraint.
With the force /moments result from Caesar back in your Fe-Model to calculat the stress.