Is it not conservative approach to apply static seismic force on structure in AutoPIPE as done in STAAD?
Yes, it is more realistic for the program to apply the seismic forces on the structure. Alternatively, you can calculate the loads on the piping system in AutoPIPE, and then transfer those loads to STAAD using PipeLink. The reverse of getting structure from STAAD through PipeLink is also possible.
"Static Earthquake" - AutoPIPE Load Case