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RE: "J" BOLT PULLOUT

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AISC Steel Design Guide 1 "Column Base Plates"

"Slip-Pullout Strength of Hooked Anchors" by Kuhn and Shaikh, University of Wisconsin - Milwaukee, Dept. of Civil Engr. and Mechanics, May 1, 1996.
Use the equations with a degree of caution.  There is no upper bound to the hook extension.  It was not researched specifically.  But in the equation theory you could fully develop a 3/4" anchor bolt with 5 inch embedment and about a 5 foot hook.  These equations are also called the WJE and Clemson equations.

The following is a bit of a "don't use J bolts" digression:
I have been arguing against using hooked anchor bolts for over 20 years.  And just because you don't have tension load in your anchor bolts in the structural design, there will be tension in the anchor bolts during erection.  Hopefully OSHA subpart R will finally bring this consideration to the attention of practicing engineers.  I have investigated and read about several column erection failures that would not have happened if a headed anchor bolt was used.

Former iron worker who saw a column fall,
Harold Sprague, PE
Krawinkler, Luth & Assoc.
4412 W. Eisenhower
Loveland, CO 80537
970-667-2426 voice
970-667-2493 fax
hsprague(--nospam--at)klaalov.com

-----Original Message-----
From:	George Barclay [SMTP:gbarclay(--nospam--at)lgt.lg.com]
Sent:	Tuesday, June 23, 1998 7:00 AM
To:	'SEAOC(--nospam--at)SEAOC.ORG'
Subject:	"J" BOLT PULLOUT

I am working on a seismic retrofit job that involves placing additional
uplift forces on the existing foundations.  The steel columns are
attached to drilled piers via "J" bolts.  I have a single sheet of "J"
bolt allowable uplift loads that was published in 1970 and references
the 1969 ACI 318.  The new uplifts exceed the allowable uplift per the
"J" bolt data.  The client, who has some structural background, is
suggesting that these values are very conservative (i.e. we don't need
to spend the money modifying the column/foundation attachement).  

I remember seeing some research several years ago that suggested that
"J" bolts were very inefficient for pullout and that they should not be
used for such.  Does anyone know of a reference on "J" bolt pullout
design or some research on this subject?  Can a "J" bolt develop a shear
cone?  Any guidance would be appreciated.

Thanks,

George Barclay P.E.

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