Dear many specialists.

I'm doing piping stress analysis for a power plant then based on EN1998-4_Part.4 : Silos, tanks and Pipelines
I used to apply static seismic analysis based on coefficient calculated UBC or ASCE..
But EN1998-4 is the first time to use.
EN1998-4 probably suggests the calculation method as response spectrum analysis but also they indicates to allow "lateral force method" of (linear-elastic) analysis.

anyone knows or has experience to use static analysis based on EN1998-4?
I wonder if the acceleration value should be calculated by nonstructural element formula (4.3.5.2 Verification_EN1998-1).

In fact such amplification for non-structural components can be found also in FEMA P-1050 and NCEER formulation. See for example P-1050, Figure C13-3.1 formulation for "ap" as function of structural and component periods, where "ap" has a trapezoidal shape.
In both cases- Eurocode and FEMA- the target is to count two effects: one is the amplification within height range of structure another is the resonance with structure. In Eurocode the effects are kept in a single formula, in American literature they are separately presented.
It is preferable to work with story spectrum (if available) instead these approximations. I had an offshore case where in a lower deck the main effect was the third mode of vibration of the structure rather than the first one. But this was a special cases and usually what Eurocode and FEMA consider as amplification for non-structural components has physical bases and must be considered.