Ring Foundation for Storage Tank

[JasonMDT]

I am currently designing a concrete ring foundation for a 90' diameter jet fuel storage tank in seismic zone 3. Per API 650, the tank will not be anchored to the foundation. How does one account for the lateral and overturning forces applied to the foundation? I haven't yet found a publication which addresses this.

 

[strucengr]

Probably my reply comes late to you. I am assuming that you went through the Appendix on Seismic forces. If the equations indicated that there was no anchor required for the tank then there is no uplift. If i recall correctly there are threee situation 1) no uplift 2) uplift present no anchor required 3) anchor required. The equations take that into effect. The equations were derived more from practice and by studying the effect of tanks in a seismic event. You would however, need to check for sliding.

check out this papere which I co-authored:

http://www.seaint.org/seaocconvention/convention1999/Proceedings/DynamicAnalysis.pdf

Aswin Rangaswamy, P.E
SHA Coffman Engineers, CA

 

[MaxJasper]

Evolution of Seismic Analyses of Unanchored Tanks:

http://www.engr.csufresno.edu/~aelzeiny/PhdThesis/node15.html

 

[Hookem]

API 650 contains seismic design of tanks. I have developed spreadsheets. Commercial programs are also available.