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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.


George Barclay P.E.