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Re: screws in plywood shearwalls

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There seem to be a lot of screws with ICBO ERs for shearwall applications.  That
does not necessarily make it a good idea.
As far as I know these were monatomic load tests.  The only cyclical tests with
screws that I'm aware of were performed with steel studs.  Under these
conditions the screws did well because of the studs' limited ability to create
fixity in the screw.  (The screws experienced little bending force.)
If the screw's threaded area sees much reversed loading it is very prone to
sudden, brittle, fatigue failure.  I would be very cautious about the wholesale
use of screws in wood framed shearwalls.
Chuck Utzman, P.E.

Dan Morrow wrote:

> Try ER-5280, an ICBO Report for "Grabber" screws.  Table 4 lists allowable
> shear values for shear walls.
>
> Dan Morrow
> Swenson Say Faget
> 2124 3rd Ave. Suite 100
> Seattle, WA  98121
> 206-956-3745 (direct)
> 206-443-4870 (fax)
>
> -----Original Message-----
> ----- Original Message -----
> From: Francisco Duarte <fduarte(--nospam--at)LEASUNG.COM>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Thursday, July 13, 2000 12:20 PM
> Subject: wood screw replacing nails at shear walls
>
> > HELP, HELP, HELP
> > My client wants to use screws instead of nails for the shear walls.
>
> Why?
>
> I would not use screws for timber framed plywood shearwalls esp if you're
> looking for ductility.  A lot (if not most) of a shearwall's ductility comes
> from nail yielding....I would not depend on screws behaving the same way.
>
> > Where can I get some information and shear values for screws to replace
> the
> > 8d nails. Is there a ICBO REPORT?
>
> I suggest contacting APA.  I'm sure they have info on this.
>
> regards
> Bob Kazanjy
>
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