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Re: R value for log walls

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Captain's Log:

How about R=1?  If you determine a realistic "R" value, you will be the first one.  They are determined by committees and infamous consensus process.  They do reflect what our experience has been with these established structural systems after some California earthquakes, i.e, the "end result.  And ATC has done some work, I recall, on "R" values and what's wrong with our present approach.  Then there are, no doubt, the politics of "R" value codification-- which might make someone's product or system less competitive, if the "R" value is too low.  But I used to build these things as a kid; and they could take 1 g, no problem.  Seems like such a house would be stiff and strong, so would move with whatever the ground motion gave it.  And I suspect you won't have to be worrying about the 2 x sill plate problem, or someone "nailing" them incorrectly.  That's all I can offer, without a log-log plot.  But have never heard of anyone playing pick-up-sticks with one of these homes after an earthquake.

James Bela

Oregon Earthquake AwarenessTM        /        The Quake NorthwestTM
"We Have Nothing To Fear But Shear Itself"        /        "We're All Subducting In This Together"

Peter McCormack wrote:

I am in the process of developing a MathCAD template for
determining seismic loads per UBC.

However, I need to determine a realistic "R" value to assign to log
walls acting as both shear and load bearing walls. Obviously, a wall
constructed of logs stacked 1 above the other has a higher density
than a light framed shear panel, but is not as dense as a concrete
or masonry log wall.

Does anyone have any suggestion, is there a calculation method to
determine it based on the material density???

Any help will be appreciated

Peter McCormack
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