Circular Ties in Concrete Pile

[J1D]

In pile design, 10M (approx #3) @12” ties are usually specified (from what I know) regardless of pile diameter, etc. I wonder if this is always good from you experience? And the ties are cut with certain overlap (e.g. 16”) only, no hooks! This has bugged me for a while. From the function of transverse rebar, the hook is definitely required in column, but for piles because of the soil restraint …… What do you think?

 

[JAE]

Yes, you are on the right track. Remember that for drilled piers, ACI 318 doesn't control (see its chapter 1). The soil helps confine the pier (piles are driven not drilled).

CRSI has a recommended Class A lap for circular ties in columns - which, for a #3 bar in f'c = 4000 psi concrete is 14".

Weird, but in the same CRSI manual, for drilled piers, they call out a lap of 48 x db which is 18" (Class B lap) for a #3 tie.

 

[Zambo]

"Piles are driven not drilled" what does this mean? Bored piled are drilled, driven piles are driven. Perahps this is US terminology causing a bit of confusion.

Zambo

 

[haynewp]

If you have significant lateral loads on the piles (pile resisting lateral loads via moment), then you can certainly have larger than #3 ties.