] [Thread] [Date] [Author]

["La Count, Curt" <Curt.LaCount(--nospam--at)Jacobs.com>]

George,

The reference I use is LRFD Volume II, and the "J" bolts are shown on page
8-89.  You will find that larger tail lengths are required to develope a
significant capacity for the bolt.  This  type of anchorage is not
recommended for uplift forces.  Another reference is Fischer 1981,
"Structural Details in Industrial Buildings", Engineering Journal, Vol. 18,
No. 3 (3rd quarter).

I hope that this has been helpful.

Curt La Count, P.E.
Jacobs Engineering
Portland,OR
 ----------
From: George Barclay
To: 'SEAOC(--nospam--at)SEAOC.ORG'
Subject: "J" BOLT PULLOUT
Date: Tuesday, June 23, 1998 5:59AM

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.