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Re: Plywood rigid diaphragms

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John-
I have always designed plywood diaphragms as flexible.  There are some
instances where they may become stiff enough to be considered rigid (very thick
blocked diaphragms, or plywood with concrete over the top), but most are
considered flexible.
I know the military considers plywood as flexible (see the tri-services
manual), and DSA and OSHPD consider plywood diaphragms as flexible.  If SEAONC
has some new information on this issue, I would like to see it.
If this is true, we may be looking at seismic retrofit of millions of buildings
with plywood diaphragms !!!

Lynn

John Buchanan wrote:

> Hi-
>
> Just finished seaonc wood design seminar. An interesting issue was raised
> regarding the design of shear walls and diaphragms.
>
> According to the presenters, design engineers should consider the
> horizontal wood diaphragms as rigid elements, and distribute the horizontal
> shear to the shear walls based on a rigid analysis.
>
> Of course at this time no one has any published data on the relative
> rigidities of the shear walls other than longer walls are stiffer than
> shorter walls!!!!
>
> Does any one have any comments on this analysis approach for light frame
> wood construction?
>
> John Buchanan