Minimum Transverse Reinforcement Ratio For Cast In place Concrete Pile

[last500]

I need help identifying what the minimum transverse reinforcement ratio is for a 12-inch diameter drilled pile. fc=6000psi fy=60000psi. The 2007 California Building Code section 1810A references ACI 318 21.4.4.1-3. Section 21.4.4.1 says that the minimum transverse reinforcement ratio is given by the equation r=0.12*fc/fy. This gives me a reasonable result. There is a comment below that equation that references ACI 318 eq. 10.5 which is for columns. My question is which equation governs. If I use ACI 318 eq. 10.5 the required transverse reinforcement gets a bit out of hand requiring a #5 spiral at 3-inch pitch. I know that designing from the gut is not the best idea but I have seen quite a few pile cages go in the ground with much smaller spiral steel at a greater pitch. Any help on this would be much appreciated.

 

[JAE]

For one thing, ACI 318 doesn't apply to piers/piles. Check out ACI 336, found here: ACI 336 link

The only place you'd use 318 is in the top of the "pier" where it comes out of the ground and is essentially a short column, - in those areas the typical column tie requirements would control.

For the in-ground piers, ties can be less intense.

 

[wannabeSE]

JAE,
The 2006 IBC has similar requirements to the CBC.See section 1810.1.2.2 for cast-in-place pile reinforcement requirements in SDC D thru F. This section references ACI 318-05.

 

[JAE]

I think it is chapter 1 or 2 in 318 where they specifically exclude piers from 318. I'm not sure why the CBC would back reference 318 for piers.

 

[last500]

Thank you all for the replys. This was very helpful.

 

[dik]

Did I miss the answer to the question? Not familiar with IBC or CBC...

For 12 and 16 inch piles, I typically use a single 15M bar (#5) by 6m long (approx 19')

Dik