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Re: A325 anchor bolts

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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.


 Robert Kazanjy, PE  **Disclaimer: I speak for myself not UC-Irvine**
 Senior Development Engineer
 Civil & Environmental Engineering
 UC Irvine
 E4130 EG,  Zot: 2175

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?