Capacity, design values for a whole log
Capacity, design values for a whole log
(OP)
I have an application with whole logs being used, basically the only milling done is having the bark removed. I was wondering just how strong a log is when compared to sawn lumber. You would think that leaving the cell structure of a log alone would be stronger than the individual pieces of that log. What would you use for design values . . . we were thinking DF-L #2 would be conservative, but just wondering how high we could take that. We have designed to the NDS values for round columns, which says to make the section an equivalent square post, and so I was wondering what a fair value for the compressive stress would be.






RE: Capacity, design values for a whole log
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or International Log Builders Association at
http://www.logassociation.org/
RE: Capacity, design values for a whole log
I engineer a lot of log homes and pole barn type structures. I usually use the full section properties of the round log rather than using a square equivalent. It isn't hard to figure the section properties of the round log. If you aren't having the logs graded and aren't sure what you have as far as quality, then use a conservative value such as WWPA No. 2 DF. If you have the logs graded then you know what you have and can then use the proper allowable based on the grading system whether it is TPI, WWPA or another system. From my experience most grading systems other than TPI don't grade the raw logs.
RE: Capacity, design values for a whole log
http://www.woodpoles.org/EngineeringDesignInfo.htm
For bending design values be sure to consider the NDS Form Factor, Cf for round sections (also how to treat circular tapered sections).
Also the NDS design equation is different for shear (parallel to grain), when compared to rectangular members.
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