what is the minimum spacing of rebar in concrete piles?

[Mina Kromer]

It was difficult for me to find this info. I found and attaching it.

From ACI 336.3R-93
4.2.2-- The clear spacing between vertical reinforcing
bars should be at least 3 times (preferrably 5 times) the
size of the maximum coarse aggregate or 3 times the bar
diameter whichever is larger.
4.2.3-- Vertical splices of reinforcing bars are
permitted and should conform to the requirements of
ACI 318. Generally, no more than 50 percent of the bars
should be lapped spliced at one location.

From Indian IS 2911 (Part 1/Sec 3) : 2010

6.12.3 The clear horizontal spacing between the
adjacent vertical bars shall be four times the
maximum aggregate size in concrete. If required, the
bars can be bundled to maintain such spacing.

 

[north_man]

Piles where I’m from are usually designed with the minimum amount of reinforcement since it’s usually skin friction which governs. I’ve never checked minimum spacing because I’ve never had to add more than the minimum amount of reinforcement. Not sure how it is elsewhere.

 

[jayrod12]

Piles where I’m from are usually designed with the minimum amount of reinforcement since it’s usually skin friction which governs. I’ve never checked minimum spacing because I’ve never had to add more than the minimum amount of reinforcement. Not sure how it is elsewhere.

This is true for me as well.

 

[dik]

If they are friction piles, the concrete should be vibrated to consolidate the concrete against the soil in addition to the rebar.

 

[Mina Kromer]

It was difficult for me to find this info. I found and attaching it.

From ACI 336.3R-93
4.2.2-- The clear spacing between vertical reinforcing
bars should be at least 3 times (preferrably 5 times) the
size of the maximum coarse aggregate or 3 times the bar
diameter whichever is larger.
4.2.3-- Vertical splices of reinforcing bars are
permitted and should conform to the requirements of
ACI 318. Generally, no more than 50 percent of the bars
should be lapped spliced at one location.

From Indian IS 2911 (Part 1/Sec 3) : 2010

6.12.3 The clear horizontal spacing between the
adjacent vertical bars shall be four times the
maximum aggregate size in concrete. If required, the
bars can be bundled to maintain such spacing.

Also, from From ACI 336.3R-93 - 4.4.3. , the minimum clear spacing between vertical rebars must be minimum of 3 in. [76 mm])

 

[Mina Kromer]

Piles where I’m from are usually designed with the minimum amount of reinforcement since it’s usually skin friction which governs. I’ve never checked minimum spacing because I’ve never had to add more than the minimum amount of reinforcement. Not sure how it is elsewhere.

In this project the piles are subjected to lateral loads, this generates moments at the upper end up to about 6 meter below the ground surface. Also in this project the subsurface layers contains Sabkha soil (very loose soil) so it is required the reinforcement to continue up to the lower end of pile.

Please correct me if I am wrong, I analyzed the part of the length of the pile of (thickness of the sabkha layer + 2 * diameter of pile) and put the moments resulted from the LPILE software moment diagram. I considered this length as an unconfined length, to consider the slenderness effects. The moments at the ends of this part are lower than the maximum design moment from the diagram. Is this enough to consider the loose soil layer ?
And of course I designed the section also for the maximum moment with maximum axial force case.
Also designed also for a case of axial tension with shear (lateral force).