earthquake check for tank - new api650 11th

huangyhg

earthquake check for tank - new api650 11th
i try to check the hoop stress due to the earth quake based on the new api650 11th.
the equation e.6.1.4-4a have the terms "cc" and "s" which are not included in the notations.
anyone know what they are ? and how do i get those values?
thanks
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the 10th edition, addendum 4, omits these factors but also has lower constant terms.  awwa d100 currently uses the same factors as in the 10th edition.  i'm not sure what the equation is intended to be, or even if the change was intentional or not.
concrete or steel tank?
api-650 is welded steel flat-bottom tanks for oil storage.
it seem to me i dont have to do checking the hoop stress due to the earthquake.