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RE: Relative Stiffness of Wood Shearwalls

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Dennis:

1. The issue of relative stiffness using different materials is moot with me
- I simply won't do it. I have been searching for information in the 97 UBC
that I thought stipulated that relative stiffness could not be used in the
design of plywood shearwalls in one common line of shear. Possibly someone
can clear this up - simply, all walls in the same line of shear must be
sheathed with the same materials and the same nailing.

If you have just 2 shear walls in a line, one perforated and one not.  How do you propose the walls share the load?  And do you still expect them to nailed the same.  Or, if you have a roof or diaphragm step that necessitates the difference in aspect ratios (i.e. relative stiffness) between two shear walls in line, again how do propose the walls share the load?

Considering rigid diaphragm rotation, you're going to have dissimilar systems (if material differences are present) sharing load based upon their relative stiffness.  It shouldn't matter there.

 
As far as Hardy is concerned, their just interested in two things.  Selling more product and limiting their liability.

Keith De Lapp, P.E.
KDL ENGINEERING


-----Original Message-----
From: Dennis Wish [
mailto:dennis.wish(--nospam--at)verizon.net]
Sent: Wednesday, May 19, 2004 8:55 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Relative Stiffness of Wood Shearwalls


I'm getting into this discussion a little late but want to add some
thoughts:

1. The issue of relative stiffness using different materials is moot with me
- I simply won't do it. I have been searching for information in the 97 UBC
that I thought stipulated that relative stiffness could not be used in the
design of plywood shearwalls in one common line of shear. Possibly someone
can clear this up - simply, all walls in the same line of shear must be
sheathed with the same materials and the same nailing. Conversely, Hardy
specifically lets engineers know that you can not mix frame or panel sizes
in one line of shear. In Rigid analysis, I believe the opinion is that while
relative stiffness of walls can be balanced, they are not assumed to be
constructed in the same line of shear resistance.