Need experts suggestions

I am currently designing a structure for supporting a steam drum (approximate weight is 164 ton) at a height of 6.8 meter from ground surface. I am confused about the type of analysis I've to perform. Mainly concerned about either shall I go for 1st order analysis or 2nd order. (loads applied are desd weight of equipment, structure, piping, access platform, seismic load, temperate load)
Looking for valuable opinions and experts suggestion in this regard. Further , how shall a structure designer pic the type of analysis.? Are there any standard guidelines in AISC or ASCE standards..?

Thanks in advance.