Designing a Concrete pad

[ViggeJay]

I am designing a circular concrete pad for a exterior tank. This pad would sit on a footing. My questions whether we would design this pad as a column or a slab from ACI 318-19. Currently I have used enercalc to design this pad but there is no option to make the pad circular. I have converted the circular area to a square but I have a feeling that is not going to give the correct answer. Any ideas?

 

[HTURKAK]

designing a circular concrete pad for a exterior tank. This pad would sit on a footing.?????

Circular pad is already foundation itself. What is the reason for placing the pad on footing? Please provide a sketch and some descriptive dimensions.

 

[ViggeJay]

Circular pad is already foundation itself. What is the reason for placing the pad on footing? Please provide a sketch and some descriptive dimensions.

Please see edited post!

 

[EngDM]

Circular pad is already foundation itself. What is the reason for placing the pad on footing? Please provide a sketch and some descriptive dimensions.

If grade isn't prepped or is full of compressible organics, or the bearing surface that can adequately support the load is far down, you'd need the footing.

 

[ViggeJay]

If grade isn't prepped or is full of compressible organics, or the bearing surface that can adequately support the load is far down, you'd need the footing.

My question isn’t really if I need the footing or not, but how to design a circular concrete pad. You can basically assume this pad is on a slab on grade and is needed because of drainage purposes.

 

[JStephen]

On a foundation that small, there may not be much difference in cost between round and square. Round uses less material, but the square is simpler to form and build.
If the foundation is part of a secondary containment system, it would need to be built per ACI-350 rather than 318.

 

[GeorgeTheCivilEngineer]

If grade isn't prepped or is full of compressible organics, or the bearing surface that can adequately support the load is far down, you'd need the footing.

I can see the need for a footing but less so the pad!

 

[ViggeJay]

On a foundation that small, there may not be much difference in cost between round and square. Round uses less material, but the square is simpler to form and build.
If the foundation is part of a secondary containment system, it would need to be built per ACI-350 rather than 318.

I think the client has requested a round pad and so I am stuck doing a round. But I am asking wether I would design it as a slab or a column

 

[EngDM]

I can see the need for a footing but less so the pad!

If anything it should be a pad and pier foundation, seems like a huge waste of concrete to pour it solid.

 

[HTURKAK]

My points ,

-This is a small tank. You may design the foundation as inverted square bowl slab found. with size 17 ftX 17 ft .
- the tank pad inside the dike wall could be a round pad having dia 13 ft and height say 10 in. and casted together with bowl found.
- make sure that the foundation soil is capable and if necessary , consider soil exchange. etc.