Hello prubhviteja
That is an interesting question. In the case of a vessel on legs, there are two modes of vibration. They as lateral (side to side) vibration which flex the legs, and there is pendulum or cantilever vibration such as would be experienced by a tall tower supported on a skirt. PV Elite really tries to estimate the cantilever vibration, but the method is not exact as the derivation is very complicated.
Normally vessels on legs are small and vibration is not really. A critical vessel should really be supported on a skirt, or in the case of a horizontal vessel, support on saddles.
Two method are available in PV Elite. They are by an Eigen solver, and the other is by a numeric method from the published paper by C.E. Freese.
This may not fully answer your question, but that is how PV Elite attempts to estimate the vibration for vessels on legs.
_________________________
Sincerely,
Ray Delaforce
CADWorx & Analysis Solutions
Hexagon PPM