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RE: A325 anchor bolts

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Beside the reduction of the tensile capacity due less than full thread
engagement problem, I would also check your concrete capacity.  I am not
trying to open up a can of worm here, but in general, A325 high strength
bolts is rarely used for anchorage.  Using A325 bolts for anchors in
cast-in-place concrete usually requires a very deep embedment and a
special reinforcement detailing to ensure for ductile performance, i.e..
concrete must have adequate strength to develop yielding of the bolt.  I
would check this condition first  and check if have adequate factor of
safety.  Remember that the published yield strength of the bolts is
normally the minimum yield.  Actual yield could go 10 to 20% higher.

Rudy Mulia
> -----Original Message-----
> From:	Robert Kazanjy [SMTP:rkazanjy(--nospam--at)]
> Sent:	Wednesday, November 04, 1998 3:30 PM
> To:	seaint(--nospam--at)
> Subject:	Re: A325 anchor bolts
> Nuts are sized to reliably develop the threads to which they are
> attached when the nut is fully engaged.   I believe that your 1.25"-7
> UNC nut is about 1.06" thick.  Full engagement means about 7.5 threads
> your missing .25 to .375 means 1.75 to 2.8 fewer threads engaged.
> About
> 25 to 35% loss of thread engagement.  Doesn't sound too good.  Can you
> afford that kind of loss assuming a linear loss of capacity?  Beware
> of
> thin wall coupling nuts I've had some break  before yielding the
> threaded rod being coupled.  Chipping out the concrete to regain your
> thread length sounds like the safest bet.
> regards
>  Robert Kazanjy, PE  **Disclaimer: I speak for myself not UC-Irvine**
>  Senior Development Engineer
>  Civil & Environmental Engineering
>  UC Irvine
>  E4130 EG,  Zot: 2175
>  rkazanjy(--nospam--at)
> Chris Palmateer wrote:
> > I have a job in which the contractor installed the anchor bolts for
> > moment
> > frame to low.  The bolts are 1-1/4 in. A325 with heavy head nuts.
> How
> > many
> > threads does it take to fully develop the bolt?  If the bolts lack
> 1/4
> > to
> > 3/8 of an inch from extending through the nut completely, how does
> one
> >
> > calculate the reduction in the capacity of the bolt?
> >