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Re: Screwed Gypboard Shearwalls

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Michael Valley wrote:

> On Fri, 19 Jun 1998 13:52:19, Roger Turk wrote:
> > Gypboard should not be used for shear walls anywhere!
>
> Generally, there is nothing wrong with using gypboard shearwalls in
> NON-SEISMIC applications.  The concern in seismic application
> centers on strength and stiffness deterioration due to cyclic loading
> in the inelastic range.
>
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> - -

Michael
I agree with your comment  "concern in seismic application
centers on strength and stiffness deterioration due to cyclic loading
in the inelastic range".  IF the structure is designed to remain truly
elastic during the maximum credible event for the site in question then
an all gypboard system can in fact perform very well.  Trouble begins
when a mixed system of variable ductility elements is employed.
Drywall can and does work in seismic applications but not with
ridiculously optimistic Rw's.  (BTW for those of you who will disagree
and flame me; a Motel 6 near Parkfield, no plywood & all gypboard, was
subjected to very large PGA;  No damage).  Drywall can work, the
structure just needs to be engineered correctly.

To answer the original post, screws provide a marginally stronger but
less ductile system.  Also screws tend to break, nails yield but with
ultimate loads of 100lbs per foot it does really matter much.

Robert Kazanjy, PE  **Disclaimer: I speak for myself not UC-Irvine**
 Senior Development Engineer
 Civil & Environmental Engineering
 UC Irvine
 E4130 EG,  Zot: 2175
 rkazanjy(--nospam--at)uci.edu