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Re: Hardy Frame, shear walls

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Dennis, 

The Z-wall was the other one I was talking about that I checked out in their
website(hawaii50.com/zwall) a few months back with complete details and
calculations in it. I don't know it it has ICBO or L.A. City approval.

Even then, when I saw it, I didn't pay much attention to it because of my
concerns in my previous post. But now that we might have the 2:1 h/d limit on
plywood shear walls, I might consider using this under cerain conditions and
more research on its performance. I'm sure a lot of similar products are out
there and there will be more new ones coming out taking advantage of this new
restriction. I think it should be tested not by ICBO or any private testing
agency only but by schools(engineering students with faculty supervision),
steel agencies(AISI/AISC,etc), and engineering asssociations(LGSEA, SEAOC,
Etc.). Then, depending on test results, it might gain wider acceptance or
there will be improvements in design and restrictions in its application
including possible classification of this type of shear wall system
in the Code. Just like the tests on tilt-up and slender masonry walls
conducted by joint engineers, contractors and manufacturers where they found
out that these wall can deflect so far and still not fail. It also removed the
H/t Code limit on slender walls.

In certain situations(like the ones you're in), I would consider using it but
with a seismic factor for braced frame along the wall line only  and not in
combination with other shear walls in the same wall line. I will also check
and double check to make sure the buckling  and welded connection failure of
light gauge subjected to seismic force in a rigid braced frame configuration
is really tested and researched thoroughly. I suggest that while LGSEA or
other groups are testing plywood shear walls on light gauge metal studs, they
consider these types of framng configuration on narrow shear walls as part of
their test.

Right now I still use a cantilevered steel column fixed at the base with
concrete grade beam, using a seimic factor with Rw=3, and not in combination
with any other type of shear wall on the same wall line. On two story houses
where the narrow walls do not stack, I use rigid a steel frame with bolted
connections or a shop welded connection if the frame is small enough knowing
how most framers dislike field weling. I like its flexibilty and therefore
more capacity to absorb and dissipate seismic forces(the same concept I see in
comparing plywood shear walls with nails on wood studs with the same plywood
screwed to metal studs). I also add a separate wood post, if there is extra
space, to carry all vertical loads if the steel column is under a beam, to
partially satisfy concerns in the SEAOC Blue Book about the cantilevered
isolated column type of shear resisting system. But I still have to look
closer at the shrinkage and deflection compatibility of the two columns.

Ernie Natividad