Underground Concrete Tank

[boricuastructural]

Im designing for the first time a water cistern. Its going to be 10 ft underground, ist 20ft by 12 ft and its going to contain 10,000 gals. My question is about the foundation, does the ground slab provides the foundation for the cistern walls or it needs independent footings?

 

[MarcbSE]

Typically the base slab is the footing. I might consider thickening the slab at the walls if the tank was large in diameter with significant overburden on top.

Just check the vertical shear at the base slab and you will see if it needs to be thicker or not.

 

[connect2]

try;
PCA publication,'Rectangular Concrete Tanks'. Mine is dated 1994. Anybody aware of a latter version, or wether this has been pulled, thinking seismic of course. In particular Manobe, Okabe Articles written in 1926 and 1929 no less. Anybody have copies of these papers
Okabe, S. 1926. 'General Theory of Earth Pressure', Journal of Japan Society of Cvil Engineers 12,1.
Manobe, N. and H, Matasou. 1929. 'On the Determination of Earth Pressures During Earthquakes'. In the proceedings, World Engineering Congress.