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Re: Shear-off bolted connection

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It's not surprising that a manufacturer of DTI's would claim
emphatically that DTI's are the best method. But the facts are that any
of the four methods approved by RCSC (the Research Council on Structural
Connections) will provide acceptable bolt installation for pretensioned
applications when used properly.

The four methods are:

	turn-of-nut method
	calibrated wrench method
	alternative design fastener method (such as a twist-off bolt)
	direct tension indicator method

Any of these methods can produce unsatisfactory results if not applied
properly. All can be used successfully if applied properly. Refer to the
RCSC Specification (particularly Section 8 and it's Commentary) for a
discussion of these four methods.


Maria I. Falconi wrote:
> Dear All,
> Thanks for all the responses.  I was intrigued by these DTI's, and found a
> web page on them-
> and based on the stuff they're
> saying, DTI tensioning is good and the other types are awful (DTI's are
> given a 100-120% tightening range whilst twist-offs are given 0-100% ???).
> Maybe we can elaborate a bit more on these two types of bolt tensioning.
> Now I'm worried that the twist-offs aren't reliable enough.  Is the
> twist-off good enough?  Is the DTI lots better?  Or are they both just as
> unpredictable?
> Maria Falconi
> -----Mensaje original-----
> De: Harold Sprague <harold.sprague(--nospam--at)>
> Para: 'seaint(--nospam--at)' <seaint(--nospam--at)>
> Fecha: Jueves 14 de Enero de 1999 06:44 PM
> Asunto: RE: Shear-off bolted connection
> >I don't know for sure, but I believe that Bethlehem does not make the bolts
> >any more. But I believe that Ingersol Rand still makes the tool as do other
> >tool manufacturers. It's been awhile since I installed them, but I believe
> >that the twist off bolt is universal and will fit any of the installation
> >tools.
> >
> >Another manufacturer is T. S. Bolts and Tools by the Bristol Machine Co. in
> >Walnut, California 800-798-9321.
> >
> >On another thread I noticed the DTI load indicating washer. It too is a
> >good product, but the iron workers prefer the twist offs because:
> > 1. The LeJeune gun is electric not pneumatic. No long air hose or
> >compressor. The electric gun is lighter and the chord is lighter.
> > 2. The LeJeune gun is not an impact tool and can be handled with one
> >hand.
> > 3. You can see if the bolt is tight by long distance observation.
> >
> >The structural engineers generally prefer the DTI's because of the
> >perception that if in the process of tightening a bolt group, a bolt is
> >relieved of tension, it can be seen in the gap. That perception may not be
> >accurate. The deformation in the dimples of the DTI is a plastic
> >deformation. That is the reason you can not reuse them.
> >
> >In any bolt "tensioning" process, the bolts in the entire group must be
> >brought to snug tight prior to final tensioning. Proper tensioning requires
> >special inspection to confirm the process.
> >
> >Regards,
> >Harold Sprague, P.E.
> >The Neenan Company
> >harold.sprague <mailto:harold.sprague(--nospam--at)>
> ><mailto:harold.sprague(--nospam--at)>
> >
> >
> >-----Original Message-----
> >From: Robert Rollo [mailto:rrollo(--nospam--at)]
> >Sent: Thursday, January 14, 1999 11:45 AM
> >To: 'seaint(--nospam--at)'
> >Subject: RE: Shear-off bolted connection
> >
> >
> >
> >does bethlehem still mfr the LIB system, with the ingersol rand tool ?
> >are they compatible ?
> >
> > -----Original Message-----
> >From: Harold Sprague [SMTP:harold.sprague(--nospam--at)]
> >Sent: Thursday, January 14, 1999 12:40 PM
> >To: 'seaint(--nospam--at)'
> >Subject: RE: Shear-off bolted connection
> >
> > Contact the LeJeune Bolt Co. in Minnesota @ 800-872-2658. They
> >handle the
> >bolts and the installation tools.
> >
> >Regards,
> >Harold Sprague, P.E.
> >The Neenan Company
> >harold.sprague(--nospam--at) < mailto:harold.sprague(--nospam--at)
> ><mailto:harold.sprague(--nospam--at)> >
> >
> >
> > -----Original Message-----
> >From: Maria I. Falconi [ mailto:maisabel(--nospam--at)
> ><mailto:maisabel(--nospam--at)> ]
> >Sent: Thursday, January 14, 1999 11:56 AM
> >To: seaint(--nospam--at)
> >Subject: Shear-off bolted connection
> >
> >
> > Dear Colleagues,
> > I need to find information about a type of bolted construction that
> >involves bolts that have a spigot at the end of the thread which shears off
> >at tightening when the required torque is reached.
> > Special power drivers are used to install bolts in this fashion. I need
> >to find out about purchasing and/or renting these machines.
> > I got a hold of a brochure from RTB Tooling (Rapid Tension Bolts) which
> >talks about these tools but I don't have enough information (no phone
> >number, etc).
> > The description of how the RTB works is as follows:
> >"After the connection is fitted, the outer socket of the tool applies a
> >clockwise rotational force to the nut as the inner socket applies a counter
> >clockwise force to the spline. When the fastener exceeds the required
> >tension, the spline end will shear".
> > I would greatly appreciate any information on where to get a hold of
> >suppliers of this type of equipment, in the States or in South America. I'm
> >
> >looking at erecting a 10-story steel building with this system (1200 tonnes
> >of steel involved) and I urgently need to price the purchase or lease of 13
> >of these power drivers.
> >
> >Regards
> >
> >Maria I. Falconi
> >Guayaquil, Ecuador
> >
> >
> >
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