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Log home shear walls

Log home shear walls

Log home shear walls

It's been several years since I did a log home lateral analysis; and I'm trying to find which R and Cd to use. The building department referred me to the ICC 400, but it seems to be silent on these factors. Can anyone point me in the right direction, thanks!

RE: Log home shear walls

Allso, you can look at ICC 400-2007: Standard on the Design and Construction of Log Structures at this site.


Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Log home shear walls

ICC 400-2007 is also silent on these factors, (I looked at ICC 400-2012 earlier) and the log building website has research papers but I do not see anything where the Code states the values to be used.

RE: Log home shear walls

So use R=2 and Cd=2 for light frame others. If you are still concern use R=1 and Cd=1.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Log home shear walls

What is the mechanism of energy dissipation in a log shear wall? Once friction is overcome at the horizontal interface between logs, I envision the walls racking back and forth like a deck of cards which would dissipate tons of energy. Of course, the system would behave pretty elastically prior to friction being. overcome.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Log home shear walls


These structures can have vertical pins as well as end rods to help with the shear as well as overturning. Depends a lot on the manufacturer and type of joinery.

Mike McCann, PE, SE (WA)

RE: Log home shear walls

For the shear values of bolts and other fasteners in wood there is this nifty online calculator by the American Wood Council:



RE: Log home shear walls

The log homes I have designed are interlocked at the corners. Olylog screws are used at each course to connect it all together. At the corners, full height rods with take up devices are used for hold downs. If not kiln dried, the log can shrink considerably. I think there was an article written years back by Tom Beaudette, an engineer with a great deal of experience in log homes justifying an R value of 4 because of the ductile nature of these buildings. Search for him online and you might find the paper.

RE: Log home shear walls

My other problem is the 1:1 minimum aspect ratio required by the ICC-400, which limits the number of walls we can actually use for shear along a given line (just one wall in my case). And, because I do not have that much shear along that particular line, the required shear values are high (1500#/' IIRC) that Olylog screws won't work, and the 'holddown' rods are at each end of the particular panel instead of at the corners of the building, with 7" square plates for the compression. I use 7/8" threaded rods at 24" o/c. for shear.

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