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RE: Steel-Detail: Flexible wind moments

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Tom Murray was my steel design professor back in the day, and I recall
some off the cuff remarks about this design check.  He had mentioned
that this check hadn't traditionally been performed and wasn't included
in the ASD manual solutions (1/2" plate extension contolling the
design?!?!).  I assume that he (or other like-minded individuals)
prepared the LRFD examples and got it built-in to the manual.

The buckling length is a function of the nominal setback plus a 1/4"
assumed fabrication underrun on the beam length (chosen based on
experience - make it bigger if you want).  This gets you to the face of
the supported beam.  From there, add in the dimension to the start of
the welds (if applicable) or the first bolt line.  In other words, where
does the restraint to buckling start?  'K' can be less than one as shown
in the examples.

Hope this helps.  LRFD/ASD doesn't matter - if you need to check a limit
state in one method, you need to check it in the other (can't wait to
put the green book away for good).

Regards,
Eric 

-----Original Message-----
From: Dave Lowen [mailto:jatech(--nospam--at)kwic.com] 
Sent: Wednesday, June 29, 2005 2:02 PM
To: seaint(--nospam--at)seaint.org
Subject: FW: Steel-Detail: Flexible wind moments 

I am forwarding this query (that I cannot answer) from another list.
Can anyone enlighten both the author and myself?

Regards,
Dave

-----Original Message-----
From: steel-detail(--nospam--at)yahoogroups.com [mailto:steel-detail(--nospam--at)yahoogroups.com]
On
Behalf Of cap'n ron
Sent: Wednesday, June 29, 2005 2:02 PM
To: steel-detail(--nospam--at)yahoogroups.com
Subject: Steel-Detail: Flexible wind moments - almost finished

In ASD solution to flexible wind moments - plated flange connection -
there
is no calculation for compressive strength of compression flange plate.
In LRFD solution there is.

For the formula Kl/r, The length "l" is taken as 3/4 inch, the beam
setback
plus 1/4 tolerance.  This is for the welded plate.

If I bolt the plate, do I increase "l" to the first bolt line? In other
words 1.5bA? Or is it the same 3/4 inch?  In the example, why is "l" set
at
3/4 inch and not 1.5bA (the unrestrained portion of the plate) on the
welded
plate?

Ron Yeager
rgy(--nospam--at)penn.com







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