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RE: drywall, seismic

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Ted,
I've looked at the website on the SureBoard and they have an ICBO
Evaluation Report listed on their website dated in 2000. The report is
suppose to be re-examined in one year, but I did not check ICBO's
website to determine if an updated report is on file. 

The only caution I would give, as the system looks interesting to me, is
that Omega needs to be adjusted in Seismic Zones 3 and 4 for a value of
3.0 when Wind governs and 2.5 when Seismic Governs.

My concern has to do with the high values given in the tables - over
500-plf for even the lightest materials connected with 6" spacing on the
screws (Bugle Head type screws). The current code values for lateral
design on steel studs was not calculated on the capacity of the plywood.
Unlike the APA tests, the Tests that were done at UC Irvine (I believe
this is who provided the reduced shear capacities that appear in the 97
UBC over the previous APA rated values) was based upon buckling of the
studs and shearing of the screws. The stiffer studs (18 and 16 gauge)
resulted in shearing in the screws at lower values and that severely
reduced the shear capacity of the panels. With 20 and 22 gauge studs,
failure occurred in the buckling of the studs before failure of the
screw and the edge of plywood tear-out. This is one reason why the 97
UBC recommends 18 and 20 gauge studs over the 16 gauge studs formeraly
recommended in the APA report used in most jurisdictions (it was not in
the 94 UBC if I recall). I think that APA disagrees with the work that
was done and may have updated their tests. I have not followed up to see
if in fact they are taking any further action to compete with the
current values.

It's been a long time since I have reviewed all of the code test
information and if anyone has more current information from the LGSEA
Newsletters and test reports that were done through the organizion,
please correct me. Any error is not intentional.

I'm sure that the values obtained in this evaluation is based on testing
of the panels and not simply on the capacity of the screws. The
connection of the 22-gauge steel plate to the face of the studs is
similar to the narrow panels produced under the Hardy Panel trademark
(this used to be Simplified Structural Systems and was later bought out
by another large company). Living in California, I am interested in
these panels as CEMCO is a well known company in city of Industry who
are known for good products. 

I am pleased that you brought this to my attention although I have not
done a lot of steel stud design here in the desert because of the energy
loss and the need to use wood trusses for the roof. From my experience
with steel stud construction is that the contractors think this is a far
superior product to wood and if the quality of construction and the time
that contractors need to train in the proper construction and
installation of Steel Stud - especially with wood trusses or floor
joists, I might agree. However, the quality and the expectation that I
have seen used her is less than acceptable. In one project, there was no
consideration to lateral design in a two story commercial building where
the architect was located in another state and unfamiliar with seismic
design. This probably would have held true with wood, but there may have
been more alternatives for shear transfer at higher loads (this is
before I knew of the CHEMCO products) with conventional wood products.

I ultimately lost this project (and don't know if it was ever
constructed) because I was arrogant enough to disagree with the
architect and the owner who was the contractor.

I plan to dig into the information on the SureBoard and have downloaded
their software. It appears to be a much needed product for steel stud
design which has a lower lateral load value with plywood panels than
traditional wood design. 

Dennis S. Wish, PE

-----Original Message-----
From: Ted Cushman [mailto:ted.cushman(--nospam--at)verizon.net] 
Sent: Saturday, October 05, 2002 5:47 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: drywall, seismic


Hello,

You folks concerned about the values of gypsum shearwalls may be
interested in the product publicized by this website:

www.SureBoard.com

It is a steel shear panel with integral gypsum board facing, as far as I
can tell. I can't vouch for it myself (don't know what it costs either),
but the company claims it has higher values than plywood for shearwall
construction and matches up with regular gypsum board dimensions to
allow easy installation and finish alongside ordinary board.
Noncombustible as well apparently.

--
Ted Cushman
Senior Editor, Journal of Light Construction
6 Pleasant Court
Great Barrington, MA 01230
phone: 413-644-8928
fax: 413/644-9575
email: <ted.cushman(--nospam--at)verizon.net>
www.jlconline.com



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