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Re: Moment Frames with Slip Critical Shear Connection

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These seem like reasonable and rational questions, and not simply semantics.

This exchange brings to mind, in at least a faintly familiar sort of way,
some of the questions, concerns, and limitations that E. P. Popov quietly
expressed regarding welded-flange/bolted web steel moment connections under
cyclic loads, pre-dating Northridge, and the quiet "hush" over those matters
until "Pandora's box" was opened in 1994.

I don't think this way of dismissing the questions and the questioner helps
the cause of the steel industry, and would urge you (Charlie) to try to
achieve a clearer understanding and resolution off-line, and to advise this
List of the outcome.

I'll look forward to a more appropriate and considered response from AISC.

Mark D. Anderson  PE
Anchorage, AK


----- Original Message ----- 
From: "Carter, Charlie" <carter(--nospam--at)aisc.org>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, August 02, 2004 7:45 AM
Subject: RE: Moment Frames with Slip Critical Shear Connection


> Well, we're just going in semantic circles at this point. I'll prefer to
> leave it until the differences of opinion can be settled by something
> tangible. If you can offer that, I am all ears.
>
> Charlie
>
>
>
> -----Original Message-----
> From: Sherman, William [mailto:ShermanWC(--nospam--at)cdm.com]
> Sent: Monday, August 02, 2004 9:09 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Moment Frames with Slip Critical Shear Connection
>
> Charlie Carter wrote:  "I'd like you to show me how to erect a beam so
> that
> bolts are not in bearing due to dead weight."
>
> My Response (Bill): I think you answered this question in your own
> answer
> regarding "banging bolts" in the 07/01/1999 Steel Interchange: "Leaving
> the
> drift pin in as bolts are installed and tightened tends to center the
> holes
> in the connected plies and increases the potential for slip in the
> connection."
>
> Charlie: "Load reversals are covered under a separate requirement in the
> specification, so need not be used to confuse the questions here."
>
> Bill: If a roof is subject to wind uplift, the vertical reaction at the
> beam
> connections may reverse from downward to upward. If bearing bolts are in
> bearing for a downward load, won't they need to slip for an upward load?
> Why
> isn't that an issue here?
>
> Charlie: "I was asking why you disagree with the rational thought that
> went
> into the AISC recommendations you questioned."
>
> Bill: Clearly the snug-tight condition for bearing bolts is not intended
> to
> prevent slip - otherwise a slip-critical bolt must be used, by
> definition.
> In my opinion, assuming that bearing bolts are always in contact in any
> connection where the bolts are on a different faying surface than the
> welds
> is not "rational". I have offered my opinions as rational thought until
> offered clear evidence that reality is different.
>
> Charlie: "But all that has been offered to date is theory and opinion,
> which
> is counter to the long-standing performance record of what is being
> questioned."
>
> Bill: So far, no clear evidence that bearing bolts may always be assumed
> to
> be in bearing has been offered - just "theory and opinion". The "banging
> bolts syndrome" seems to raise questions regarding the "long-standing
> performance record" of such connections. Per R. Schwein's article on
> "The
> Banging Bolt Syndrome": "The moment resisting connections with welded
> flanges and bolted webs would be less prone to this bolt slip because
> the
> flange welds, being stiffer, would attract and resist most of the strain
> before the load would cause bolt slips in the web." Please explain how a
> welded flange can deform sufficiently for bolts to slip into bearing at
> a
> web connection, such that the weld will not carry "an indeterminately
> larger
> share of the load". To date, I do not think that AISC has presented a
> clear
> case for its apparent position on this issue.
>
>
> William C. Sherman, PE
> (Bill Sherman)
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
>
>
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