Punching Shear and piles

[MrFurleyEIT]

I've got a question about punching shear and piles. I am designed a piled isolated spread footing. I have several pile caps, with no. of piles ranging from two to six. For this exercise, let's say we have six piles.

Now, each pile would have a certain allowable capacity, calculated by dividing the total service load on the pile cap by the number of piles.

Okay, so how do I determine how many of these six piles (in this example) contribute to the punching shear? For example, if my pile is directly under my column, I would not include it. Do I include only piles that are outside of the critical section, that is, piles that are outside the (c+d/2) perimeter.

Appreciate any help.

 

[UcfSE]

Piles outside the critical section will contribute to the footing shear, beam shear and punching. See section 15.5 of the ACI 318.

 

[WillisV]

You should also check the additional limit states for "deep beam" type shear that are not directly covered by ACI.

These checks for punching and flexural shear are performed at the face of the column and can be found in the Pile-Cap section of CRSI.

 

[civilperson]

The load divided by the number of piles is not the load for shear, rather the allowable MAXIMUM, (service), load of that type pile. The piles will not be loaded uniformly in moment situations or in eccentric loading. Piles outside of the d/2 from column face will contribute to punching shear, each at allowable service load.