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RE: QUERY: Steel Connection Design Philosophy

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Bill,

I kind of play it a bit on the fuzzy side.  I use a default minimum table
that is predicated on the amount of load that the beam can carry for normal
spans.  If the calculated forces due to point loads indicate a higher force,
that greater force is indicated on the plans and the beam connection is
designed for the higher force.  

Minimizing connections can buy you more problems, if you are not careful.
One mistake that I have seen engineers make (and good detailers catch) is
the T/2 minimum connection length requirement.

Regards,
Harold Sprague


> -----Original Message-----
> From:	Bill Polhemus [SMTP:bpolhem(--nospam--at)swbell.net]
> Sent:	Wednesday, July 26, 2000 9:43 AM
> To:	seaint(--nospam--at)seaint.org
> Subject:	QUERY: Steel Connection Design Philosophy
> 
> Here's one to file under the "Things You Thought You Knew But Now Realize
> You
> Might Be Wrong" category.
> 
> I had engrained in me somehow the idea that when one is designing a
> connection
> of any kind for structural steel, one makes sure the connection is at
> LEAST as
> strong as the member(s) being connected. In other words, regardless of the
> design forces, make sure that if an overload were to occur, the connection
> would
> NOT fail before the member did.
> 
> However, reading the applicable passage from the AISC LRFD 2nd Edition,
> J1.1, I
> find this:
> 
> "[C]omponents shall be proportioned so that their design strength equals
> or
> exceeds the REQUIRED STRENGTH DETERMINED BY STRUCTURAL ANALYSIS FOR
> FACTORED
> LOADS ACTING ON THE STRUCTURE, or a specified proportion of the strength
> of the
> connected member, whichever is appropriate." [Emphasis is mine]
> 
> Now, the latter clause seems to give you wide latitude. For instance I
> could say
> that "I've determined to use a specified proportion of the strength of the
> connected member in this structure, that proportion being 100%". So I'd
> not
> really be WRONG. It becomes a question, then, of philosophy.
> 
> This comes up, of course, when for practical reasons you have members that
> are
> more than adequate to handle the required loading, and a connection sized
> according to that member's capacity would mean adding bolts or weld, etc.,
> above
> that required to resist the loads from analysis.
> 
> I'd like to know what others have decided in their approach to steel
> connection
> design.
> 
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