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# CORRECTION: Screwed Gypboard Shearwalls

• To: seaoc(--nospam--at)seaoc.org
• Subject: CORRECTION: Screwed Gypboard Shearwalls
• From: Bruce Shephard <bruce.shephard(--nospam--at)opus.co.nz>
• Date: Mon, 22 Jun 1998 16:31:57 +1200 (NZST)

```I have a corrrection to make to my previous posting please:

With false arithmetic in converting from "bracing units" as used in the
code, and not thinking, and little 'feel' for metric units the given
shearwall resistance values are grossly in error.

200 bracing units = 1000 kg x 10 m/sec.sec Newtons
20 BU = 1 kN

"Braceline" on one face, "Giboard" on other face, with specified nailing,
gives 150 BU's per metre for walls 1.2 m to 2.4 metres long and 2.4 metres
high.  E.G. 150/20 = 7.5 kN per metre.  12 kN hold-down straps are required
at each end.

Incidentally,  I understand that the nailing system provides the ductility.
Hence the performance when using washers under the nails.  Nailing is at 150
mm centres to edges with washers fitted, and double nails without washers to
the interiors.  The hold-downs are 1 mm thick strap with several nails to
the timber stud.

Thanks Thor, for discretely pointing out my error.

Previous message:

" I was happy 'lurking' to see what "good ole USA" had to say.

NZ has a brand name "Giboard" and "Braceline" system consisting of cardboard
sheathed gypsum board, with nail, and nail and washer, fixing systems which
are rated for shear wall resistance by test.   The Braceline system can be
configured for up to [[7.5 kN]] per metre wall length.  One side timber stud
wall lined with "Giboard" is good for [[2.5 kN]] per metre wall length
minimum.

The testing agency (Building Research Association NZ) has a site with
information available for purchase at:

www.branz.org.nz

The supply company from whom literature is obtained is:

Winstone Wallboards Ltd
P O Box 12-256
Penrose
Auckland
New Zealand
Telephone +64 9 633 0100
Fax  +64 9 633 0101

They provide free information plus 'design' software.

Screw fixings are not used.

I THINK design is based on fixing capacity at 18 mm deflection for 2.4 metre
stud wall height.

>  > Subject: Screwed Gypboard Shearwalls
>  > ...............>the nailing while the screwed non shearwalls looked
>  >great.  Has anyone ever
> >seen or allowed screws to be used in lieu of the nails?
> >
> >Patricia Small
> >Tucson, AZ
>
>
> I have seen such systems in New Zealand before I left there in 1991.
>  There were also on or two systems that had national approval to the
>  extent that some developers started looking at building entirely out of
>  drywall units called, I believe, "Triwall".  Whether that system has
>  still developed or not I don't know.  Bruce Shephard in NZ may be able
>  to enlighten us.  It would seem to be highly quality assurance-dependent.
>
> Thor Tandy
> Victoria BC   "

--------------------------------------------------
Bruce Shephard, Principal Consultant Seismic Risk
Opus International Consultants, New Zealand
DD Telephone +64 4 4717597,  Fax +64 4 4711397
Email bruce.shephard(--nospam--at)opus.co.nz
--------------------------------------------------

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