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Re: Anchor bolt confinement in pedestals

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Richard

This seems to be a matter that has been incompletely thought through, or at
least incompletely coordinated in the ACI Code.

ACI Appendix D seems to be based on unreinforced concrete but doesn't
explicitly limit its procedures to unreinforced concrete.  The requirement
for ties at the tops of columns and pedestals in ACI 7.10.5.6 does not state
a relationship between design of the anchor bolts to be enclosed and their
design.  The commentary states that confinement improves the anchor bolt
load transfer, but does not quantify that improvement.

The July 2004 issue of Structure Magazine, page 39, discusses an approach to
designing anchor bolts in pedestals.  The article concludes with some
questions and comments that I hope future editions of ACI 318 will clarify.

Nels Roselund
Structural Engineer
South San Gabriel, CA
njineer(--nospam--at)att.net


----- Original Message -----
From: "richard lewis" <rlewistx(--nospam--at)juno.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Thursday, October 14, 2004 6:54 AM
Subject: Re: Anchor bolt confinement in pedestals


| I appreciate all the discussion this subject has brought up.  It is
| interesting to learn the history some times.
|
| But . . . .  I wonder if you could answer my question concerning the
| ties, etc.  My original question was how to bring together the anchor
| bolt shear and concrete breakout strength per PCA and ACI design
| requirements and the concentration of ties at the top of the column/pier.
|  If I put the 4-#3 ties at the top do I not need to consider concrete
| breakout from the shear load.  If I do, then how would one calculate it?
|
|
| For the time being I just calculated the shear strength of the concrete
| based on the ties and considered that good enough.
|
| Rich
|
| On Wed, 13 Oct 2004 11:16:19 -0400 "Wesley Werner" <wwerner(--nospam--at)conewago.com>
| writes:
| > You can find it in ACI 318-02 section 7.10.5.6.  This section is new
| > to
| > ACI 318-02. It requires (2)- #4 bars or (3) - #3 bars in the top 5"
| > of
| > pedestals containing anchor bolts.
| >
| > Wesley C. Werner
| >
| >
| > -----Original Message-----
| > From: Will H [mailto:haynewp(--nospam--at)hotmail.com]
| > Sent: Wednesday, October 13, 2004 9:55 AM
| > To: seaint(--nospam--at)seaint.org
| > Subject: Anchor bolt confinement in pedestals
| >
| >
| > I usually see something like (4)-#3 ties @ 3" o.c. enclosing
| > anchor bolts at
| > the top of a concrete pedestal which is supporting axial load
| > from a column.
| >
| > I am having trouble finding something in ACI that describes this as
| > a
| > detailing/design requirement. Does anyone know where ACI
| > addresses this or
| > has designed for this before?
| >
| >
| >
| > Will Haynes, P.E.
| >
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