Tank Design-New API650 11th- Equake Check

[tngv752]

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.

 

[JStephen]

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.