Usage if Seismic Importance factor for lethal vessel as per ASCE 05

[ting123]

Dear Eng. Members,

My query is "what seismic importance factor shall be used while designing a lethal vessel(column)ground supported. If client specification says that the occupancy category is III then as per ASCE- Table 11-5-1 importance factor is 1.25. Does OC III includes hazardous material?. Furthermore as per para 13.1.1 it should be 1.5 for component containing hazardous material. Is it acceptable to use 1.25 saying that requirement of chapter 13 are not applicable as it is for "non structural components" and not "building structures" or " non building structures"

I express my sincere thanks to all members in advance for your valuable help.

 

[SIGrkr]

Don't count on your client to provide the occupancy, but in this case the client may be correct. Cat III and IV depend on the type and quantity of hazmat being stored. Check Table 1-1 and check with your jurisdiction for special requirements or just assume Cat 4 and move on. Self supporting nonbldg structures are in Chapter 15. Don't forget secondary containment.

 

[JStephen]

Double check with the client.
In some of the tank standards, there are only three categories, with III being the highest with a factor of 1.5. That may be their intent in specifying III.
In vessel design, "Lethal service" is a very restricted definition, and a lot of vessels storing hazardous chemicals are not considered to be in Lethal Service.