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perforated shear walls

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Chris:

reference:  SEAOC Seismic Design Manual Volume II, pg 69. You may have to
struggle a bit to understand the statics behind it, but it's very
"rational". It's also very tedious to do by hand.

The spandrals over the openings often have the highest shears using this
method.  It just doesn't make sense to try to use a perforated panel
analysis when your openings are very large in comparison to the size of the
solid panel that is left.

APA also has a publication on perforated shearwall analysis which I believe
you can download from their website.  I have not reviewed it.

Karen Casano, SE
San Diego, CA
----------------------------------------------------------------
Re:  Timber Design.

=20

I=92m flustered.  I=92ve been working for over two years and have yet to
come up with a definitive method for designing shear walls with
openings.  I=92ve come to find there isn=92t one.  I was attempting to =
use a
method that is included in the 2000 IBC ( we call it the =93AFPA=94 =
method,
based on an article I=92ve read by Philip Line ) where the ratios of the
opening height to wall height and opening width to wall width are used
to calculate a reduction factor and require the designer (myself) to
increase the nailing in a shear wall.  Over the past year, I=92ve read
about four or five different versions of that article and now have come
to the conclusion that the detailing requirements make it
=93near-impossible=94 to make the method work in areas where the walls =
are
SEVERELY impacted.  It makes some sense that any method would have
problems when you=92re trying to force a wall that=92s 18=94 wide to =
handle
8000# of shear.  We work primarily with Excel spreadsheets for this sort
of analysis, and if there=92s a method that doesn=92t fit into a spread
sheet well I probably haven=92t seen it yet.  I also found an =93old=94
spreadsheet in the office archives detailing out how to determine the
strap force (and of course the strap callout) above and below window
openings, but when trying to follow the equations (going cell to cell) I
start to get lost and in the end it=92s just a bunch of numbers =
crunching,
and I=92m not buying it enough to explain to any plan checker such that
they=92ll buy it either.  I was hoping that someone reading this list
would either be willing to fax a method they=92ve used (no numbers =96 =
just
the method please) or know of a publication or something to help
reference a =93rational method=94.  Every time I ask about this problem =
I
always hear just use a =93rational method=94. =20

=20

In case you=92re still reading and curious, I have a wall that=92s =
19=92-7=94 in
height and collects and drags load from both the roof (at 19=92-7=94) =
and
the second floor (at 10=92-6=94), and otherwise requires 2x6 DF#2 @ 8=94 =
O.C.
to resist out of plane wind loads.  In fact, wind controls the in-plane
design loads.  The total wall length is 21=92-6=94 with a 120-50 window =
at a
header height of 8=92-0=94 and another 120-50 window at a header height =
of
18=92-0=94.  The section of wall on the left side is 6=92-3=94 in =
dimension and
section of wall on the right is 2=92-9=94.  To be honest, I=92m fudging =
the
numbers on the dimensions slightly, reducing the length of wall several
inches on each.  Using these wall dimensions and the =93AFPA=94 method, =
I
get a 2-sided =BD=94 plywood 10d 2:12 wall.  Ouch. =20

=20

Oh =96 and using that old spreadsheet with no real knowledge of how it
works or where it=92s based isn=92t in my interests. =20

=20

=20

Thanks.

=20

=20

Chris

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