Foundation Strength.

[Inestine]

Hello I have a question for you guys.
I want to construct a building to house a water tank. simply.
The tank is going to be an oval shape of 40 feet long, 20 feet wide and 56 inches high. holding approximately 28000 gallons.
According to my calculations this will weigh approximately at 25 degrees c, 8.3 lbs per gallon, or 232400 lbs total. Average...
This is an average of 292 lbs per square inch if I am right.
Standard Portland cement has a rating of 3000 lbs.
Would a regular 4 inch foundation slab with 5/8" steel re bar and mesh steel, be sufficient to support this weight?
Please highlight any points I may be missing....
Thanks...

[Cake of Doom]

With any foundation design, the concrete comes second to ground conditions. Foundations for aqueous retaining/holding vessels/structures need to be analyzed for both the fully loaded and empty states as a foundation designed only for the fully loaded state can experience uplift when all load is removed and in extreme cases, failure. There is also dynamic loading to consider for when the tank is filling or emptying.

You will need to consult with an Engineer to ensure all proper design criteria are met. I would recommend liaising with your S.E. whom will then get in touch with any other relevant branch of engineering.

Good luck with your project.

[Inestine]

ok cool. and while i do understand your point. Imagine that the tank is a sealed vessel ok, the liquid is never in contact with the actual foundation. It is just supported but it. that is the real value of the question. Can you say anything about that from that point of view. Do you think it would be adequate or do you think more reinforcement or a thicker slab should be cast? By the way this is my personal project on private lands, so thats why im consulting here to make sure i get it as right as i can. Thanks for your reply.

[Cake of Doom]

ok cool. and while i do understand your point. Imagine that the tank is a sealed vessel ok, the liquid is never in contact with the actual foundation.

I never said the liquid would be in contact with the foundation so I don't know where you got that from.

It is just supported but it. that is the real value of the question. Can you say anything about that from that point of view. Do you think it would be adequate or do you think more reinforcement or a thicker slab should be cast? By the way this is my personal project on private lands, so thats why im consulting here to make sure i get it as right as i can. Thanks for your reply.

I don't think you do understand the points. You can make this foundation as big as you like, with as much re-bar as you like but it's useless if the ground that the foundation is based on isn't good enough to support it. The only way you'll find that out is with a Geotechnical report.

[Kelly_Bramble]

There are several foundation references the include the engineering calculations for foundations here:

Civil Engineering Design and Engineering

[Inestine]

Ok cool. thank you very much.