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RE: SStud: Need opinions about residential construction andsteelstud shearwalls -Reply -Reply -Repl

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Thank you Dennis for the explanations on the APA report. The quote
was to the point. I welcome your review of the Segrette document.

>>> "Dennis S. Wish" <wish(--nospam--at)key.cyberg8t.com> 12/05/97 01:07pm >>>


-----Original Message-----
From:	Tim McCormick [SMTP:TMCCORMI(--nospam--at)BAS.CI.LA.CA.US]
Sent:	Wednesday, December 03, 1997 10:22 AM
To:	seaoc(--nospam--at)seaoc.org
Subject:	Re: SStud: Need opinions about residential construction
andsteelstud shearwalls -Reply -Reply

Dennis,

You raise the issue of stud buckling as the failure mode for structural
wood panel shear walls on metal framing. Does the APA report show
buckling at the wall ends? Can this be resolved by additional studs at the
wall end? If so, will this change the failure mode to the fasteners?

[Dennis S. Wish]  Tim, yes Table #4 in APA's Report #154 by John R.
Tissell, PE which was dated May 1993 shows the mode of failure for
each gauge stud and panel combination. With the exception of 14 gauge
studs the mode of failure indicated was "studs buckled". The load factor
(factor of safety determined by dividing the ultimate load by the target
design shear) varied from 2.8 to 3.7 where the studs buckled.
However the text contains the following paragraph on page 9:
"Most of the walls tested failed prematurely when the end studs buckled
or the bottom plate buckled at the buttress of the test fixture due to
tearing of the bottom track at the anchor bolts. The tests did not provide a
true indicator of the capacity of sheathing panels fastened to framing
due to the weakness of the metal framing. Shear walls using metal
framing require careful design of the end studs as highly loaded
columns, and sufficient anchor bolts to provide for shear transfer from
the bottom plate into the foundation or to the diaphragm supporting the
wall."

Tim, in all fairness, I have not completed a review of LGSRG-3-96 -
Shear Wall Values for Light Weight Steel Framing as prepared by Hoang
Nguyen and Georgi Hall for the Project Director Reynaud Serrette for the
Light Gauge Steel Research Group, Department of civil Engineering,
Santa Clara University. Professor Serrette has been leading the way in
his research on steel stud shearwalls and has been very active by his
research sponsor - AISI as well as his association with the Light Gauge
Steel Engineering Association. I suspect that it is this document which
lead to the 1997 UBC provisions.

I will review the document and report back as to what changes have
been achieved.

Dennis Wish PE