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RE: aci 318-02 appendix d

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'h' is not the embedment depth. It is the thickness of
concrete. Edge effect is embedded in psi6. If c2>1.5c1
then psi6=1. psi5 accounts for the the eccentricity of
bolt CG in relation to the CG of the foundation
footprint. If h >=1.5c1 and c2>=1.5c1 Vb is
proportional to (c1)^1.5. If c1 is large, Vb will be
large too, meaning that the breakout strength in shear
will not control design.

I don't see any confusion in using the referenced
section.

Rajendran


--- "Lutz, James" <James.Lutz(--nospam--at)earthtech.com> wrote:

> Jack, this problem has been driving me nuts since
> you called me up to talk
> about it this morning.
> 
> We are talking about the breakout strength of an
> anchor in shear. This is
> taken as a basic value Vb times a series of
> reduction factors, Av/Avo, psi6,
> and psi7 (leave psi5 out of the discussion for now,
> since it's an adjuster
> for group action). Psi7 is just a constant, so it is
> not relevant to the
> discussion either, which centers around the
> equations that include edge
> distances c1 and c2 in them.
> 
> The Vb value is proportional to c1^1.5, with no
> apparent limit other than
> the fact that at some point Vs will control
> capacity.
> 
> The Av/Avo value cannot exceed 1.0 and is intended
> to adjust for the ratio
> of the actual thickness of the concrete to the
> maximum of 1.5c1, and for the
> actual width of the breakout surface versus the
> maximum of 3c1. Another way
> to express this is (h/1.5c1)*(width/3c1). As c1 gets
> bigger and bigger,
> Av/Avo reduces to zero pretty quickly irrespective
> of the other variables,
> which seems a little counterintuitive to me. You
> would think that you should
> only get penalized if c1 gets smaller, not the other
> way around.   
> 
> Something about this methodology does not add up. 
> 
> 
> 
> 
> -----Original Message-----
> From: Shapton & Partners [mailto:shapton(--nospam--at)nwlink.com]
> Sent: Wednesday, May 18, 2005 1:13 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: aci 318-02 appendix d
> 
> 
> David, a little while ago I spoke with Basile Rabbat
> on this issue.  
> Basically, if c1 = infinity, how can c2 = infinity x
> 1.5 (which would 
> yield Av/Avo <1)?  This is not the intent.  B.
> Rabbat recognized the 
> issue and thought clarification would be coming.  It
> is my understanding 
> that Hilti has figured this out.  I believe the
> solution relates to a 
> concrete thickness of 1.5 x the embedment depth as
> this is thier 
> standard with Re-500 anchors. Looking at their
> tables, you can see that 
> if c1and , c2 are greater than 1.5 x the embedment,
> Av does not enter 
> into the pixcture. Sorry for the disorganized
> response, I am just going 
> out to a meeting, saw your subject, and wanted to
> send something that 
> might initiate further discussion.
> 
> Jack Shapton
> 
> David Adie wrote:
> 
> > shear force parallel to an edge
> >
> > D.6.2.1 - footnote c - recognizes the fact that c1
> in psi 6 doesn't 
> > make sense but equation D-21 includes Vb which
> still has c1 embedded 
> > in it.  what value to use when c1 = infinity?
> >
> > tia
> > da
> >
> 
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