Hi there,

I don't see any possibility to carry out with Caesar II any kind of dynamic analysis on buried piping, regardless what Code is used for analysis.

You need to go back and review Caesar II approach for buried piping analysis. Pipe material density, fluid density, insulation/lining/... density - ALL are set to ZERO and the weight affects are ignored since piping is continuously supported.
The consequence is that inertial properties of the buried piping are meaningless to be used in dynamic analysis.

Do a search on this Forum for Earthquake analysis of buried piping. I remember that long time ago, there were some inquiries and very interesting responses regarding this subject. Briefly, since dynamic analysis cannot be employed, earthquake effects might be simulated by introducing distributed strains in the buried pipe spools. American Lifelines Alliance (ALA) standard for Steel Buried Piping Analysis may be consulted in this regard - there are some indications how to assess those equivalent distributed strains.

Regards,