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RE: Shear-off bolted connection

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I think we need to balance the theoretical aspects of this issue with the 
practical aspects. Erectors and fabricators are telling us they like the 
twist-off bolts because they are easier to install and they can maintain 
higher quality. Usually, if it's hard to do something in today's construction 
industry, there's very little likelihood that it will be done well without:
a) a LOT of involvement by the SER,
b) more field inspection,
c) a contractor who cares about quality and
d) someone with enough chutzpa to tell the contractor it's not right and do 
it over again

I agree with Charlie - they all CAN perform well if installed properly. The 
question is, how hard is it for all parties involved to make sure that 
happens.

I like the twist-off bolts. I've experienced problems with DTIs myself. The 
biggest problem I've seen is that they "squish" too late in the torque 
process and bolts break off. Over-tensioning worries me more than 
under-tensioning. I'd much rather have a bolt tensioned to 50% of proof when 
90% was required vs. 110%.

Bill Keen




-----Original Message-----
From: Charlie Carter On Behalf Of Charlie Carter
Sent: Sunday, January 17, 1999 10:02 PM
To: mail@ih {seaint(--nospam--at)seaint.org}
Subject: Re: Shear-off bolted connection


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.

Charlie