Dear Forum Members,
I am working on a piping system which is partially buried and partially above ground.Refer attached snapshot.I am using Earthquake(Spectrum) module of Caesar II. I am using client defined Spectrum @ 0.2% damping.

The set of vectors I have used is as follow.
X=1.0
Y=0.7
Z=1.0

The load case for Dynamic is as follow
D1 (Combination#1)
D1 + (W+P1) (Combination#2)
D1+(W+T1+P1) (Combination#3)

The method I follow to evaluate liftoff at dynamic is as follow:
Compare the loads at Static case [W+T1+P1] in +Y support(always negative) with loads at Y support(always absolute) for Dynamic Combination#3
[ D1+(W+T1+P1)]. If the load in static case
( say - 1000N) is less than that of dynamic case (say 1100N), then the support tend to lift off.
The question I want to ask is as follow:

(1)Is my approach toward liftoff correct?
(2 How do caesar II react in Earthquake Spectrum to a line which is
partially buried and connected to a above ground line.
(3)Is is Justfied to create a lift off case in static case for the support
that lift in dynamic case by removing those +Y support and comparing
sustain stresses with Sh?

Thanks in advance
Alkesh Bhati