TL Value in API 650 Add. 4 App. E

[TankDude]

Can anyone tell me where to find the value for TL as specified in Appendix E of API 650 Addendum 4? Section E.4.9.1 states that unless otherwise specified it shall be taken as the mapped value in ASCE 7. I can't find it mentioned specifically anywhere in ASCE 7. Should I just use a value of 4 seconds? Any help would be much appreciated. Thanks.

 

[JStephen]

See Fig. 22-15 in ASCE 7-05. It varies from 4 to 16 seconds across the country.

 

[TankDude]

Thanks JStephen. I didn't have a copy of 7-05 until this morning. I guess it helps to have the most up to date reference material.

 

[TankDude]

While we are on the subject, regarding the Equivalent Seismic Design Force (E-12) and the Vertical Seismic Force (E.6.1.3), is the Weff simply the combined effective impulsive and convective weights calculated per E.6.1.1? If not, where is this weight defined? Also, I cannot find the lateral acceleration coefficient A for the equivalent lateral force calculation. As always I appreciate the assistance. I also have a suspicion that the formula for max long shell compression when J>0.785 in section E.6.2.2.1 is flawed. It appears that maybe the reduction factor in the denominator 0.18667 should be inside the brackets prior to being taken to the power of 2.3. Any thoughts or experience with that?

 

[JStephen]

There are several typos in Addendum 4, beware.

It looks like Eq. E-12 is just a generic how-the-approach-works equation that is not actually used for anything. You actually calculate the impulsive and convective coefficients separately and combine via E.6.1.5, etc.

The equation in 6.2.2.1 looks right to me. At least it agrees more or less with the equivalent AWWA D100 equation. Note that it is only used for unanchored tanks, so J will never be over 1.54.

In Eq. E-18, the "-1" should be outside the brackets of the cosh, I think.

In E.6.2.2.3, second equation, it should show ten to the sixth power, not 106.

Seems like there are some other inconsistencies as well.