Fundamental Frequency of Cylindrical Water Tank 2

[Bagman2524]

Can anyone point me in the right direction to determine the fundamental frequency of a cylindrical steel tank (~100 ft dia x 50 ft high) filled with water?
Thanks

 

[IFRs]

For seismic loading? Perhaps API 650 or AWWA D100 could help you?

 

[JStephen]

See this paper, which is the simplest way:

http://www.dec.fct.unl.pt/seccoes/S_Estruturas/Dinamica/Util/SeismicAnalysisTanks.pdf

That equation is repeated in API-650, 11th Ed., App. E. I'm not sure if they include definition of all parameters in App. E. Note that consistent units must be used in the paper above.

There is an article by Veletsos from 1974 or so that introduces a method of evaluating fundamental period. It still gets rather involved, and has always seemed less than satisfactory for actual use due to uncertainties in some of the terms. I think the paper listed above is basically a simplification of Veletsos' method.