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Re: '97 UBC - R values for structures with Pendulums

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This is exactly what we (seismology) have tring  to write an "Exception" in
the code for.  In simplistic terms, if deformation compatibility exists
between the cantilever columns and the plywood shearwall then the structure
will perform correctly.

If you have any questions please call me.

Bill Nelson

----- Original Message -----
From: <Seaintonln(--nospam--at)>
To: <seaint(--nospam--at)>
Sent: Thursday, July 01, 1999 9:35 AM
Subject: '97 UBC - R values for structures with Pendulums

> I understand the basics for using the lowest R in each direction based
> the resisting elements. However, I can't agree that the entire structure
> should be penalized when an block - isolated on three sides - is designed
> using embedded columns at the side opposite an adjacent block.
> Assume for the moment that the home was constructed with conventional
> Shearwalls of plywood. The R used in the design would be 5.5.
> A Patio cover (tile or composition roof) was built on the structure an the
> pendulums were used to resist shear on the open side.  The R for this
> be 2.2
> The code requires the entire structure in the direction of force resisted
> the columns, to be designed using the lower R value or 2.2.
> I don't accept that, with the exception of the common wall between the
> and the residence (assuming that the roof diapragm is framed separately)
> any other shearwalls will be substantially influenced by the stiffness of
> columns at the patio?
> Therefore,  how do convince not only the building official to accept my
> judgment when I can not prove it by rational analysis?
> Dennis Wish PE