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RE: Anchor Bolts in Masonry

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Matthew:

Now remember that you are comparing "apples and oranges".  The Strength
Design "answer" _SHOULD_ be greater than the Working Stess Design
"answer".  The point that Joe discovered is that the WSD equations have
not been "harmonized" with the Strength Design equations.  This means that
they are not really using the same "method" but in rather in different
forms...in otherwords, after they have been harmonized they SHOULD produce
the same answer, when you make the adjustment for Strength vs. Working
Stress methods.  As a parallel, if you computer the "allowable" moment for
a steel wide flange using ASD, that value should be less than the
"allowable" moment for LRFD...but in the same token, the "applied" loads
for ASD should be less than the LRFD "applied" loads (i.e. ASD loads are
NOT factored).

HTH,

Scott
Adrian, MI



On Thu, 18 Nov 2004, Hood, Matthew O. wrote:

> Scott and Joe,
>
> Thanks for your help. I was unable to locate the thread in the archives
> but it sounds like that's just the way it is. It doesn't make sense to
> me that the provisions for anchor bolts in concrete are so much more
> conservative (using ACI 318-02 appendix D) than those for masonry. My
> gut says it should be the other way around...
>
>
> Matthew O. Hood, E.I.T.
> Plan Review Engineer
> Municipality of Anchorage
> 907-343-8451
>
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
> Sent: Thursday, November 18, 2004 10:00 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Anchor Bolts in Masonry
>
> Joe (& Mathew):
>
> The quote was:
>
> "In my personal opinion, Eq. 2-4 is too conservative.  If augmented by
> minimum cover requirements, Eq. 2-3 is enough.  That's the way the
> strength
> provisions are written, and I would use those for anchor design.  We
> didn't
> have time to fix this for the 2005 provisions.  We hope to finish
> harmonizing the ASD and SD provisions for the 2008 document."
>
> HTH,
>
> Scott
> Adrian, MI
>
>
>
> On Thu, 18 Nov 2004, Joe Grill wrote:
>
> > Mathew,
> > I posted a question on this subject just a couple of weeks ago.  You
> might
> > check the archives for some of the replies.  Basically, yes you are
> right.
> > It gets even worse if you look at the separate definitions for Ap and
> Apt.
> > Scott Maxwell quoted an acquaintance of his who is on the committee
> that
> > agreed that the equation 2-4 is conservative, and if I remember
> correctly
> > 2-4 could be ignored if minimum cover requirements are met that 2-3
> would be
> > enough.  I won't try to remember the full quote word for word here,
> but
> > check the archives.  You are not the only one that has noticed this.
> > J. Grill
> >
> > Joseph R. Grill, P.E. (Structural)
> > Shephard - Wesnitzer, Inc.
> > Civil Engineering and Surveying
> > 1146 W. Hwy 89A Suite B
> > Sedona, AZ  86340
> > PHONE (928) 282-1061
> > FAX (928) 282-2058
> > jgrill(--nospam--at)swiaz.com
> >
> >
> >
> > -----Original Message-----
> > From: Hood, Matthew O. [mailto:HoodMO(--nospam--at)ci.anchorage.ak.us]
> > Sent: Wednesday, November 17, 2004 12:04 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Anchor Bolts in Masonry
> >
> > I'm comparing the values for breakout of anchor bolts in tension using
> > ASD and LRFD and I'm coming up with a pretty large discrepancy. I'm
> > using ACI 530-02 which has
> >
> > Ba=0.5*Ap*(f'm)^0.5 for ASD
> > and
> > Ban=4*phi*Apt*(f'm)^0.5 for LRFD with phi = 0.5
> >
> > This would mean that the strength values are 4 times greater than the
> > ASD values. Am I missing something? Does anyone know why the
> difference
> > is so large?
> >
> > Thanks for any input,
> > Matt
> >
> > Matthew O. Hood, E.I.T.
> > Plan Review Engineer
> > Municipality of Anchorage
> > 907-343-8451
> >
> >
> >
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