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Re: Anchoring to Concrete

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William,
 
Thanks a lot for your information. In fact, the procedures you mentioned, match
exactly with what has been our practice. Your info has been very helpful, much
more, since I have no reply from the people of ACI.
 
Best Regards,
 
Raul Labbé S.E.
M.ASCE.
Chief Engineer
Structural Discipline
CADE-AMEC CONSULTING ENGINEERS
 
----- Original Message -----
From: "Sherman, William" <ShermanWC(--nospam--at)cdm.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, October 19, 2004 11:01 AM
Subject: RE: Anchoring to Concrete

> I am not as familiar with the background on ACI 318 Appendix D as I would
> like to be, but I am familiar with previous anchor bolt design procedures
> such as Appendix B of ACI 349-97 and similar procedures described in the
> article "Guide to the Design of Anchor Bolts and Other Steel Embedments"
> from Concrete International, July 1981.
>
> The general intent in those documents was that the concrete tension capacity
> be developed such that it exceeds the yield strength of the anchor bolt,
> such that the ductile behavior will occur. Thus an anchor bolt embedded deep
> enough in mass concrete should have adequate concrete pullout capacity to
> initiate bolt yielding prior to concrete failure.
>
> In a pier of limited dimensions, reinforcing steel can be used to resist
> pullout where there is not adequate concrete area for a ductile design. The
> commentary for the above noted documents discusses how this can be done. In
> essence, a 45-degree cone is drawn towards the failure surface from the head
> of the anchor bolt, and the reinforcing steel must be developed both within
> and outside of the failure cone.
>
> Similar procedures are described for lateral shear failure, using a
> semi-circular failure cone initiated at the top of the anchor bolt.
> Reinforcing steel anchored on each side of that half-cone failure can be
> used to resist lateral loads in lieu of only using concrete strength.
>
> William C. Sherman, PE
> (Bill Sherman)
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email:
shermanwc(--nospam--at)cdm.com
>  
>
> > -----Original Message-----
> > From: Michael Bryson [mailto:mbryson(--nospam--at)NYASE.com]
> > Sent: Saturday, October 16, 2004 4:26 PM
> > To:
seaint(--nospam--at)seaint.org
> > Subject: RE: Anchoring to Concrete
> >
> > I think the intent of the code here is that the addition of
> > reinforcement is only meant to control cracking, not to
> > increase the capacity of the anchorage in tension. Once a
> > crack forms, the stresses in the concrete (hoop stresses)
> > change and the anchorage capacity is reduced.
> >
> > Now having said that, if more reinforcing means you have
> > smaller cracks, and since there is a correlation between
> > crack size and anchor capacity, then technically additional
> > reinforcing does increase the capacity. But I don't think the
> > code allows for this.
> >
> > -----Original Message-----
> > From: Rlabbe [mailto:rlabbe(--nospam--at)cadeidepe.cl]
> > Sent: Saturday, October 16, 2004 6:49 AM
> > To:
seaint(--nospam--at)seaint.org
> > Subject: Anchoring to Concrete
> >
> > List,
> >
> > I will require some help to see if we are correctly
> > interpreting the codes in the referenced matter.
> > ACI 318-02, ( App. D ) is determining the anchoring capacities
> > in concrete, based on the concrete breakout strength in
> > tension ( failure cone of the concrete mass ).
> > It also allows to increase this capacity, when there is no
> > cracking in the anchoring region.
> > The question is, since this capacity is based only in the
> > concrete failure, can it be increased with the addition of
> > adequate reinforcement ? i.e. enough rebar, and properly
> > placed, in the ( would be ) failure cone mass, as to take the
> > full pull-out load.
> > Appreciate your opinions.
> >
> > Best Regards,
> >
> > Raul Labbé  S.E.
> > M. ASCE.
>
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