ASCE 7-16 LN2 Tank Anchorage Question

[Exytebob]

I am designing the anchorage and foundation for a large LN2 tank (455k operating weight, 87' tall, 10' dia.). Tank and baseplate are designed by others. The design code is ASCE 7-16. The Seismic Design Category for the Tank is SDC A. My question deals with Chapters 11 and 15 in ASCE 7-16. Chapter 11 indicates that in SDC A, the seismic force for buildings and other structures is Fx=0.01Wx. I assume the tank is an "other structure" and will follow this criteria for seismic forces. In Chapter 15, section 15.4.1.2 seems to indicate that Chapter 12 be followed and Cs calculated to determine V. But, Table 15.4.2 does not include SDC A in the table which again leads me back the the SDC A seismic design requirements. Am I interpreting ASCE 7 correctly? The seismic forces on the tank should follow SDC A design criteria?

 

[HTURKAK]

..

I wish not to disappoint you but NO... Pls look 15.6 GENERAL REQUIREMENTS FOR NONBUILDING
STRUCTURES NOT SIMILAR TO BUILDINGS..and 15.7 TANKS AND VESSELS..

Is this vertical tank ? If you post A sketch showing the tank, foundation together with seismic data you may get better responds..

 

[csk62]

Woof thats a large vertical LIN tank. 15,000 gallon LIN tanks are around 43 ft high and a 10ft VJ OD, so I'm guessing this is around a 30,000 gallon tank.

It may also be the case that in this low of a seismic region that the empty tank with wind load may be the governing load combination for anchors in tension. Maybe not since the tank is quite heavy.

From what I remember tank anchorage is usually designed IAW 15.7 which requires the ductile anchor failure mode.

Also one thing that always comes up for concrete foundations for cryogenic equipment: most cryo installs will have pressure building and process vaporizers next to the tank which will leave constant moisture on the concrete and may subject the concrete to freeze/thaw cycles causing spalling. I would recommend ACI 318-14 exposure F2 which will point you to fc'=4.5ksi.



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