huangyhg

tank design-new api650 11th- equake check
i try to do the earthquake of a tank based on a new standard api650 11th edition. it's a lot different from the old standard.
i have a problem to understand the unit of spectral accerlaration parameter.
for example, "so" is the acceleration parameter at 0 second period, %g . it's meant that "so" is the max value =2.5 or 2.5g or 0.25 ???? ( g=9.81 m2/s)> say that earthquake in australia
thanks.

check out our whitepaper library.
units for so, s1, s-ds, etc, are given as a percent of gravitational force. in the seismic maps of asce 7-05 (which of course doesn't include australia), the map will show lines for 10, 15, etc., which are 10%, 15% etc. of gravitational force, and used in the calculations as 0.10, 0.15, etc.
if you are given a value of so = 2.5, i would take that as 250% of gravitational acceleration or 2.5g, which is very high seismic loading.
there are some typos in the 11th edition, also. for example, eq. e.6.1.1-3 should have a wp after it.

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