Support Foot Size/Spacing Based on Floor Load Limit

[wprouty]

We are looking at installing a test loop that requires a 7500-gallon water tank, which is 10 ft. diameter by 15 ft. tall. Because we rent our facility, we have been asked to avoid cutting the floor when installing the tank. The concrete floor is 3000 psi, 5-inch thick concrete and the floor load limit is 250 psf. Based on the floor load limit and the weight of the water and the tank, F/A indicates an area of 19 sq. ft. The question I have is whether we need to design a support structure that makes contact over the entire 19 sq. ft. area or can we use multiple feet with some calculated size and spacing to spread the load over 19 sq. ft. of floor? If multiple feet can be used, by what method do we determine the pad size and spacing required? i.e. is there some added load distribution inherent to the concrete itself or does the 250-psf limit imply the entire surface is required to support the load. P.S. If this would fall under a different forum, I am sorry.

 

[boo1]

"F/A indicates an area of 19 sq. ft"?
Based on the load limit rating you need more than 210 Sq Ft area. The load limit can be used over the entire surface.

 

[wprouty]

Not sure what you mean. For 250 psf concrete and a 90000 lb. load, the area required from a pure F/A calc. is 361 sq. ft. or 19 ft. x 19 ft.

Please clarify your response.

 

[boo1]

First, your initial post indicates: "F/A indicates an area of 19 sq. ft.", not 391 sq ft.

7500x8.33=62,475 # , add the tank DL, divide by allowable
then the 19 x 19 area is reasonable.