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RE: Is it a shearwall or not??? Need some help

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Considering AEC-Residential List is my own list - you are welcome as a
lurker or as any way you wish to participate.

I need to correct one of your comments. I never intended to use Gypsum for a
shearwall. The original construction of the wall is gypsum on both sides.
The first floor wall is about half the length of the second floor wall and
gypsum was used only on one side. The other is paneled - with a decorative
wood paneling about 1/4" in thickness - not what I would even consider a
shear element.

If I followed some of the advice I received, I should replace the capacity
of the wall that I am removing - even if it means assuming a value of gypsum
of 150-plf at each side which was code prior to 1994 UBC. Therefore, I would
need to increase the capacity of the remaining 18-feet of wall at the second
floor by the 27-feet of two-sided gypsum I'm removing (300-plf times 27-feet
or roughly 8100-pounds) ---- which seem unreasonable to me since the first
floor interior wall is most definitely inferior to accumulate shear from the
second floor wall as it exists.

I would tend to follow Martin Johnson's recommendation as well as yours,
Chris TSE and Rgrayaia@aol (Gary) and consider the wall to be non-shear
resisting based on it's definite weakness and the rationale of my previous

Thanks again to all who replied. I appreciate the help - it gave me a LOT to
consider and weigh.

Dennis S. Wish, PE
Structural Engineering Consultant
structures(--nospam--at) <mailto:structures(--nospam--at)>
(208) 361-5447 E-Fax
ICQ #95561393

-----Original Message-----
From: EphHirsch(--nospam--at) [mailto:EphHirsch(--nospam--at)]
Sent: Friday, November 03, 2000 9:43 AM
To: dennis.wish(--nospam--at); nblackburn(--nospam--at)
Cc: seaint(--nospam--at); aec-residential(--nospam--at)
Subject: Re: Is it a shearwall or not??? Need some help

I apologize, I forgot to sign my previous response, so not to seem
anonymously "lurking" please note the comments were by:

Ephraim G. Hirsch, S-1200

Comments as you requested:  If I interpret your description of the structure
correctly, I can't believe that you are considering using gypsum wallboard
resist seismic forces in a concrete building (your description), no matter
what the original designer might, or might not, have thought.  I believe you
have to ignore both stories of that interior wall as far as shear resistance
goes (I gather that it is a bearing wall however supporting  wood floor &
roof framing systems, not concrete?) and rely solely on the perimeter
concrete walls/frames (?) to provide your seismic resistance, with the
horizontal diaphragms designed (or beefed up as the case may be) to span to
them accordingly.