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Re: SStud: Need opinions about residential construction and steelstud shearwalls -Reply

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Thanks for the comments Tim (BTW, I have some for you on Conventional
Framing).
My comments regarding steel stud framing were taken from APA's research
report #154 which is the standard today. The shear values for plywood
sheathed or OSB sheathed wall panels assumed a stud of 14 through 18 guage
steel. I have been designing based upon these values and have not reviewed
the 1997 UBC values.
Personally, I would be hesitant to design with similar values for a lighter
gauge steel (20 ga) when the mode of failure is the stud buckeling rather
than a connection failure at the screws.
These, too, were static tests.
LGSEA released a report LGSRG-3-96 "Shear Wall Values for Light Weight Steel
Framing" in Feb. 1996 by Professor Serrette that completed testing using 20
gauge studs. These tests support your remarks and are probably the reason
for the revised values in the 1997 code.
I need to do some homework on this. At this time, we discussed using a more
stringent code by professional opinion as opposed to a less current code
status that may require a less conservative approach. But, how about the
opposite. Does it seem advisable to use 20 gauge studs which may be adopted
in the 1997 code when the 1994 code values are based upon 14 thru 18 gauge
materials?
I would not have a problem when considering a braced panel relying on a
steel tension strap design, but I am hesitant to recommend a 20 gauge stud
knowing that the mode of failure is stud buckeling.
Any opinions?????

Dennis Wish PE

-----Original Message-----
From: Tim McCormick <TMCCORMI(--nospam--at)BAS.CI.LA.CA.US>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Monday, December 01, 1997 12:10 PM
Subject: SStud: Need opinions about residential construction and steelstud
shearwalls -Reply


>One issue you raised was the recommended use of 16 gage studs for
>plywood shear walls over metal framing. Unfortunately, the 1997 UBC
>allowable shear value tables requires 20 gage studs. Thicker gages
>supposedly cause earlier brittle fastener failure. What happens when
>load require 18 gage studs?
>
>The City of LA had about a dozen of these buildings this year. For better
>or worse, most used the tension only bracing for lateral load resistance.
>All of these buildings uses two tracks, tack welded together, when loads
>occurred between studs.
>
>
>