API 650 Overturning Toe Pressure 1

[PEStructural]

What is the approach/equation to calculate the overturning toe pressure on a concrete ringwall in a seismic event? I have a 89'x32'H welded steel tank that is in seismic zone 4 and is resting on a concrete ringwall (not bolted down).

Any help would be greatly appreciated.

Thanks,

Mike

 

[JoeTank]

The seismic analysis of a tank is covered on API-650, Appendix E. You could use the unit vertical shell load as the load at the top of the ringwall. But, you also need to transfer some additional moment due to lateral shear times the depth of the wall.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[PEStructural]

Thanks for the quick answer Steve! One other question, I assume that I would have to add to that the DL weights of the water on top of the ringwall and the ringwall itself. Right?

Thanks again.

 

[JoeTank]

Yes, the product pressure on the top of the ringwall plus the weight (net weight) of the ringwall are additive in this case.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[JeffcoatSmitt]

Check out "Aboveground Storage Tanks" by Phillip Myers. his book has a good discussion of seismic design for both the tank and ringwall.

Jeffcoat Smitt

http://www.etank.com

http://www.fteinc.com