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RE: Drilled pier foundation

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You are correct that section 1.1.5 states that ACI 318 does not pertain to
drilled piers/caissons embedded in the ground.  Section 1.1.5 does states,
however, that ACI 318 does pertain to drilled piers/caissons for
structures of "high seismic risk or assigned to a high seismic performance
or design categories," as pointed out by some one else.  It should be
noted that this except was added in the 1999 version of ACI 318.  Prior
versions of ACI 318 (i.e. 1995 and earlier) do not contain the "exception"
for high seismic zones within section 1.1.5.  Thus, since ACI 318-95 is
the most prevalently adopted version at this time, it would be somewhat
accurate to say 318 does not pertain to drilled piers/caissons.  As the
2000 IBC code becomes more prevalent, then ACI 318-99 will become the more
prevalent "official" version.

If the exception in 318-99 is "triggered", then section 21.8.4 is referred
to for the requirements for drilled piers/caissons.  This section does NOT
any requirements relative to when the reinforcement should be placed.

The commentary for section 1.1.5 does referred to the "Design and
Construction of Drilled Piers" as reported by ACI 336.  Since this is
contained in the commentary, however, it is not part of the code and
cannot be enforced...unless it is included as part of the project's
contract documents (i.e. in the specs).

ACI committee 336 had two current publications available.  The first is
ACI 336.1/336.1R-98, which is titled "Reference Specification for the
Construction of Drilled Piers (ACI 336.1) and Commentary (ACI 336.1R)".
This document states in section 3.4.10:

"3.4.10 Reinforcement shall be placed before pier concreting begins,
unless otherwise acceptable to the Owner's Respersentative-Geotechnical

The second document is ACI 336.3R-93 (Reapproved 1998), which is titled
"Design and Construction of Drilled Piers".  Sections 4.4.3 and 4.4.4 of
this document essentially say the same thing that ACI 336.1 said.

As stated before, the "provisions" in the ACI 336 documents are NOT code
enforcable.  They can only be a requirement if they are referenced in the
contract documents or is the requirements recommended in them are inserted
into the contract documents.

Hope that helps,


On Tue, 6 Mar 2001, Pat Ebner wrote:

> ACI 318 and UBC Chapter 19  pertain to structural concrete.  ACI 318 Section 1.1.5 specifies that ACI 318 does not govern design and installation of portions of concrete piles and drilled piers embedded in ground.  The commentary on Section 1.1.5 references a report by ACI Committee 543, "Recommendations for Design, Manufacture and Installation of Concrete Piles".
> >>> paulc(--nospam--at) 03/06/01 03:36PM >>>
> Yes, there is a chance of that happening.  Futhermore, if you are in an area
> governed by the UBC or ACI 318 setting of reinforcement after the concrete
> is placed is forbidden by code (UBC 1907.5.1).  
> Paul Crocker, P.E.
> -----Original Message-----
> From: Padmanabhan Rajendran [mailto:rakamaka(--nospam--at)] 
> Sent: Tuesday, March 06, 2001 12:42 PM
> To: seaint(--nospam--at) 
> Subject: Drilled pier foundation
> Drilled pier foundations have reinforcement (vertical
> bars + ties or spirals) in the upper few feet of the
> piers. Recently, I heard that it is common for the
> construction folks to place the pier concrete and then
> push a preassembled cage of reinforcement through the
> concrete. Does this method guarantee that the rebar
> can be placed reasonably close to the way it is
> detailed on the drawing? Is'nt there a good chance
> that the rebar may be bent and mangled?
> Rajendran
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