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RE: Moment Frames with Slip Critical Shear Connection

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Yes, I am saying that the shear bolts "may not" be in bearing and thus the
shear load would be resisted by the flange welds, since the bolts cannot
easily slip due to the restraint from the welds. It is clear that
"snug-tightened bearing bolts" are not designed to prevent slip, and the
"banging bolt syndrome" seems to provide evidence that bearing bolts do in
fact sometimes slip in standard framed beam connections. Also, uplift at
roof framing members may reverse the load at the shear connection. Thus, I
believe that bolts used in conjunction with welds at a connection should be
slip-critical, unless it can be shown that there is adequate flexibility for
the bolts to slip without increasing loading in the welds. 

If the flange welds were to be checked for shear as suggested below, what
are the shear bolts provided for - just for assembly? 

I agree that banging bolts should not be a big problem "in a moment
connection with welded flanges as the welds would not allow the connection
to swiftly slip and cause the bang." The banging bolt effect is of relevance
only in that it shows that the bolts may "try" to move, but cannot move due
to the flange welds. 


William C. Sherman, PE 
(Bill Sherman) 
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)cdm.com
 

> -----Original Message-----
> From: Rand Holtham, P.E. [mailto:rand(--nospam--at)sigmaengineers.com] 
> Sent: Monday, August 02, 2004 3:07 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Moment Frames with Slip Critical Shear Connection
> 
> I may be lost in the semantics here ;>) ...Bill are you 
> saying that the bolts should be slip critical? or are you 
> agreeing with Charlie that in all practicality SC joints are 
> unnecessary??? Sounds like...and again I may be lost here... 
> that this is the case just that Charlie is saying the shear 
> bolts are likely in bearing and Bill is saying maybe not 
> (although I can't see how they couldn't be unless the bolts 
> are hit with an impact driver before the spud wrench is 
> pulled out which of course could happen). If this is the case 
> then the welded flanges are carrying both the shear and the 
> flexural stresses (except some nominal resistance in the 
> shear bolts which are slightly pretensioned). So it might be 
> a good idea (if I've followed) to check the welds for the 
> extra shear (is this what Charlie is calling unnecessary?).
> 
> IMHO I doubt banging bolts is a problem in a moment 
> connection with welded flanges as the welds would not allow 
> the connection to swiftly slip and cause the bang.
> 
> Just trying to keep up,
> 
> Rand

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