Water Tank - Center Column Bearing Capacity
Water Tank - Center Column Bearing Capacity
(OP)
I am designing a steel flat bottom water tank bearing on compacted fill. The geotechnical report states a 2000 psf allowable bearing pressure. To calculate the allowable bearing pressure for the center column foundation, do I need to subtract the weight of the water ( 62.4 * depth ) from the 2000 psf to get the allowable bearing capacity for the column foundation? Any help would be greatly appreciated.





RE: Water Tank - Center Column Bearing Capacity
RE: Water Tank - Center Column Bearing Capacity
RE: Water Tank - Center Column Bearing Capacity
RE: Water Tank - Center Column Bearing Capacity
The water pressure is driving the soil failure wedge - so technically it is "taking away from" the bearing capacity.
If the bearing capacity really is that low, you have very few options:
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See FAQ158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"
RE: Water Tank - Center Column Bearing Capacity
In the absence of any other info, the column base is sometimes designed for 1.5 times the water pressure, assuming that the part remaining for the column load is 0.5 times the water pressure.
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Water Tank - Center Column Bearing Capacity
RE: Water Tank - Center Column Bearing Capacity
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See FAQ158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"
RE: Water Tank - Center Column Bearing Capacity
This is a structural post really once the geotechnical questions have been answered with regards to settlement, Give them your footing size based on the bearing capacity they have provided you and see what they say about settlement in the area of the central column. You may need to look at the thickness of the steel floor in this area depending upon your detailing of the column base, the tank floor and the column footing. Just how thick is the fill? The load on you column and its footing may negate the fill in settlement calcs...
Unfortunately plate comes in uniform thicknesses and adding to them creates a whole different set of challanges in structures containing liquids, so yes this is the correct post, you must limit the differential settlement between the column foundation and the tank floor to nearly zero. Give the GeoTechnique guy your design, loads and assumptions and see what they say.
Your tank can't leak thats for sure.
Add the weight of the water to your footing load.
A very difficult question with very little info to go with.
RE: Water Tank - Center Column Bearing Capacity
chesney@uei-houston.com