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Re: Completly shearing a building (also answertoperforatedshearwalls)

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    In No. Cal., most engineered wood framed buildings are completely sheathed.
The sheathing serves a critical waterproofing function, particularly under board
sheathing.  In wet, windy conditions the omission of the sheathing is a very
risky proposition.
    The structural contribution of  these narrow bits and pieces is also
ignored.  They tend to be soft and/or weak and probably have a similar effect as
GWB.  They contribute to early stiffness but after a few major load cycles they
get too soft to contribute significant strength or stiffness.  However, they
probably absorb a fair amount of energy and provide significant damping.  Keep in
mind that we, in effect, divide the load by an arbitrarily chosen R factor in an
attempt to account for a multitude of dynamic effects and redundancies.
    I don't know where you got the idea that the new code encourages engineers to
try to fine tune a wood sheathed LFRS.  The commentary should make it clear that
this is neither possible, practical, or even desirable.  It is hard enough to get
proper construction of one or two types of shearwalls in a building.  To specify
a fruit salad assortment is an invitation to construction screw-ups.  To get
upset when the framers add sheathing or nails is also foolishness-- the analysis
isn't that accurate to begin with!
    I again recommend that you read the latest publication from CUREe
(particularly Ed Diekmann's paper "When 2+2=0").
    I also think Chrisopher Wright is correct.  The most important thing we can
do is to provide/require thorough structural inspections by licensed engineers.
There is probably nothing wrong with Conventional framing as long as it done
correctly.  I've seen plenty of engineered construction that scared the heck out
me--even after it was  "inspected" and approved by the EOR.  KISS and Inspect is
my motto these days.
    Chuck Utzman P.E.