Unequally loaded pile caps
Unequally loaded pile caps
(OP)
I need some insight. I am using a 6 pile pile cap as per CRSI, 1996 edition. The problem is I have a column load in the middle of the cap but I also have grade beams bearing into the ends of the pile cap. The average load per pile is 66.7k but the cap is not equally loaded.
Can I still use the 6 pile pile cap? Will the center 2 piles settle slightly allowing the load to go to the other piles?
See attached sketch. Also, should the grade beam bear on top of the pile cap?
Can I still use the 6 pile pile cap? Will the center 2 piles settle slightly allowing the load to go to the other piles?
See attached sketch. Also, should the grade beam bear on top of the pile cap?






RE: Unequally loaded pile caps
However, an unequal loading will equate to a moment at the centroid of the footing. Figure the moment from the unbalanced loads at the footing centroid like you would any other type of footing and then design your pile cap (figuring the reaction in each pile due to the additional moment and then moment and shears in your cap).
The following is a quick reference from Teng.
The load in each pile can be developed from elastic theory (assuming the pile cap is rigid, pile heads are pinned and piles are elastic columns whose deformations and stress distributions are planar).
Qm = Q/n +/- MyX/(sum X^2) +/- MxY/(sum Y^2)
Qm = axial load in any given pile
Q = total axial load on centroid of piled group
n = number of piles
Mx,My = moment with respect to the X and Y axes
x,y = distance of pile from Y and X axes
RE: Unequally loaded pile caps
RE: Unequally loaded pile caps
RE: Unequally loaded pile caps
The pile caps I've done with grade beams have had the grade beams frame into the side of the pile cap (with the same top of concrete elevation - though I don't think there's any necessity for that to be true)
RE: Unequally loaded pile caps
RE: Unequally loaded pile caps
Can I ask where you are located?
RE: Unequally loaded pile caps
RE: Unequally loaded pile caps
That's a wonderful hardware store.
RE: Unequally loaded pile caps
RE: Unequally loaded pile caps
I worked for quite a few years building homes.
That place was the mecca for tool junkies like myself.
Good quality people there.