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Re: perforated gypsum shearwall

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Daryl
For fire rating purposes, one hour wall with 5/8 inch type X gypsum wall
board applied to steel studs, 31/2 inches at 24 inches on center with 1"
type s drywall screws 8 inches on center at vertical joints and 12 inches
on centerat floor or ceiling runners and intermediate studs.  See Gypsum
association manual GA file No WP 1072.  As far as shear values are
concerned, California building code does not provide guidence on shear
values for metal stud framing. TABLE 25A-1 provide allowable shear values
for drywall on wood studs with 6 d cooler nails with different capacity for
blocked or unblocked wall construction.  In either case it does not seem to
aid the situation you have for the evlevator shaft.  I am not aware of
other publications or ICBO that addresses shear capacites with screws for
drywall.  I have to tell you, since 94 code, hardly any body I know uses
shear capcities of drywall. If you send me your fax number privately, I
will send copies of the code.
Samir Ghosn, PE
Harris & Associates
  10:09 AM 10/3/2002 -0600, you wrote:
>Samir,
>Fellow engineers,
>
>        I generally don't regard the reliability of drywall shearwalls as
>being satisfactory; neither do Canadian codes.  Never-the-less, I have to
>upgrade an existing elevator shaft which has been framed in steel (details
>posted on this list last week) for two reasons: to accommodate a new
>elevator; and to provide one hour non combustible fire protection both for
>the steel and for the adjacent stairway.
>
>        To meet these requirements the shaft will be completely enclosed
>using metal studs and drywall thereby building the existing steel framing
>inside what will, in effect, become a shearwall.  Although the drywall is not
>required for the purpose of carrying structural loads (and the only such
>loads will come from the elevator, not the building) it will receive some
>loading due to interaction with the steel framing.  That said, it seems
>appropriate to use a fastening pattern (call it nailing pattern, screw
>pattern, or whatever) conforming with standard shearwall requirements.
>
>        Could one of you please be so kind as to scan and e-mail a few
>paragraphs from one of your codes regarding drywall shearwall fastening
>patterns.  Any code will do since they don't really apply in Canada anyway.
>
>        Thank you very much.
>
>Best regards,
>
>H. Daryl Richardson
>Calgary, Alberta, Canada.
>
>Samir Ghosn wrote:
>
>> I have yet to see any body follow the nailing schedule on gypsum shear
>> wall.  Generally, the drywall sub-contractor would put the drywall and if
>> you think the guy is reading structural plans, dream on.  During my
>> forensic tenure, I hardly ever encounterd any gypboard shear wall to have
>> the proper nailing or even the proper nail size and spacing.
>> Samir Ghosn,PE
>> Harris & Associates
>> At 09:17 PM 10/2/2002 -0000, you wrote:
>> >   $
>> >>   -----Original Message-----
>> >>From: Jnapd(--nospam--at)aol.com    [mailto:Jnapd(--nospam--at)aol.com]
>> >>Sent: Wednesday, October 02, 2002 9:37    AM
>> >>To: seaint(--nospam--at)seaint.org
>> >>Subject: Re: perforated gypsum    shearwall
>> >>
>> >> perforated and    design for it......
>> >>
>> >>Joe Venuti
>> >>& Nielsen    Associates
>> >> CA
>> >>
>> >
>>
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