How do I calcuate a circular concrete column or a circular concrete footing?

[chorner26]

My footing is 3'-0" embed into the soil and had a gravity load of 1000# and a lateral load of 400# at 8"-0" above its centroid (or 3200 ft#)

Do I assume a equivalent cross section for a square shape? Ie 2/3H a and Width. this is a short concrete column. Thanks

 

[BAretired]

That approximation may be close enough, but you could calculate the pressure distribution over the circular footing due to the gravity and lateral load, then calculate the bending moment more precisely using an equivalent square column of 2/3D.

Alternatively, you could actually use a square footing with a round column. It is easier to calculate and easier to form.

BA

 

[dik]

The old ACI Column handbook had a detailed explanation of calculating Concrete column load capacities. Can you live with a square footing or possible octagonal (square with corners cut off). Forming a round footing would be extremely costly.

Dik

 

[MotorCity]

Just to be clear, I assume your load is 8' above the GROUND not above the CENTROID of the column...correct?

 

[chorner26]

Yes the Centroid is from the ground.
the contractor will be casting against the earth on this one so no forms, so my guess is he is just using and auger to drill the locations.
So does anybody have any examples (ie ACI hand book PDF or something? I want to see if I can justify not using ties if possible, but if needed then I will use them list a regular column.

 

[structSU10]

well your load is was out of the kern - its effectively a 1000# load at 3.2 ft of eccentricity. I doubt the bearing pressure with check out with that.

 

[PMR06]

This sounds like an embedded pole type foundation. If so, check out IBC section 1807.3