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Re: Effects of the New Code on Wood structures - good or bad?????

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chuckuc wrote:

> The fact of the matter is that many the wood framed structures did not perform
> acceptably during the Northridge earthquake.  As a consequence, some very
> knowledgeable and experienced engineers have proposed changes in the Code in
> order to improve the performance of wood frame construction.  Design loads have
> been increased and we are now being asked to evaluate our structures a little
> more carefully.  That is going to include an evaluation of rigid and flexible
> diaphragm performance, like it or not.

Really!!  And just where do you get your information from on this?  I
would be VERY interested in getting ANY data on low rise residential
type structures that had plywood diaphragms and plywood shear walls that
did not perform up to a life-safety level of performance during the
Northridge earthquake.

Our staff observed hundreds of such structures after the earthquake and
read all of the reports we could get our hands on about the performance
of these kinds of structures.  We have not been able to find even ONE
example of a collapse or partial collapse of these kinds of structures
where the wood framing elements were the cause of the failure.  The
Meadows was the failure of a steel column, and one house did slide down
a hill and collapse.  But that failure was to to soil stability
problems, not the wood framed elements.  There were a few others, but
the culprit never had anything to do with the wood framing.

Yes, there are some that suffered damage.  But from what I have
discovered, the failures of individual elements did not lead to a global
failure of the supporting structural framework.

My parents house is only about 2 miles from the epicenter of the
earthquake.  It is a two story wood framed house, highly irregular, with
only very small plywood shear walls scattered about the house.  The
house is 30 years old, and from what I could tell, was not even designed
adequately to the Code that was in force at the time.  My parents hired
an Architect to design the house, and hired an "Engineer" for $250 to do
some calculations and sketches for the Architect so they could get a
permit.  I was young, right out of school, and working with concrete and
steel at the time and knew nothing about wood construction so I cold not
help them.  Anyway, this and many many other similar structures only
suffered cracked plaster.  No structural damage at all!!!!  

I am of the exact opposite opinion as you as to the performance of
low-rise plywood structures during the Northridge earthquake.  If there
is information I have missed, I would be VERY interested in learning
about it.

Lynn