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Re: Moment Frames with Slip Critical Shear Connection

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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



----- Original Message ----- 
From: "Sherman, William" <ShermanWC(--nospam--at)cdm.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, July 26, 2004 9:01 AM
Subject: RE: Moment Frames with Slip Critical Shear Connection


> Charlie is right regarding what the AISC Spec "requires" but I will offer
a
> differing opinion. I feel that bolts should be slip-critical when used
with
> welds even if "not on the same faying surface". If bolts are not
> slip-critical, then it may require some movement for them to develop
> strength in bearing. But the welds will be very rigid and will prevent
> movement. Thus the welds may effectively carry all of the load until the
> welded connection deforms adequately for the bolts to go into bearing.
>
> The assumption that bolts will be in bearing due to self-weight is just
that
> - an "assumption". It is not "required" by the Spec and may not be a valid
> assumption in the case of uplift or axial load on the connection.
>
>
> William C. Sherman, PE
> (Bill Sherman)
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
>
>
>
>
>
>   _____
>
> From: Carter, Charlie [mailto:carter(--nospam--at)aisc.org]
> Sent: Monday, July 26, 2004 7:28 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Moment Frames with Slip Critical Shear Connection
>
>
>
> > ... SDC C ... designed as "steel structures not specifically
>
> >detailed for seismic resistance" (R=3).  The moment connection
>
> >consists of flange plates welded to the column and beam.  The
>
> >shear connection calls for the bolts in the shear connection to
>
> >be slip-critical.  I thought this was a requirement for moment
>
> >connections?  Do the bolts in the shear connection have to be
>
> >slip-critical?
>
>
>
> When bolts and welds share load on the same faying surface, the AISC Spec
> has a requirement that the bolts be slip critical. In this case, the bolts
> and welds do not share the same load, so that requirement does not apply.
>
>
>
> I have seen these connections specified both ways and ultimately it is a
> decision to be made by the engineer of record. I personally do not think a
> slip of any magnitude is likely in the shear connection, since that tends
to
> be brought into bearing by member self weight during erection. As a
result,
> I would be comfortable using bearing bolts instead of slip-critical bolts.
>
>
>
> Charlie
>
>
>
>
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>



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