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Taper of wood polesAuthor(s): Billy Bohannan; Hermann Habermann; Joan E. Lengel
Source: Gen. Tech. Rep. FPL-02. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 9 p.
Publication Series: General Technical Report (GTR)
Station: Forest Products Laboratory
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DescriptionRound wood pole use has changed without accompanying advancement in engineering design data. Previous pole design was based on the assumption that maximum stress occurred at the groundline but, with the larger poles that are now being used, maximum stress may occur along the pole length. For accurate engineering analysis the shape or taper of a pole must be known. Both curvilinear and straight-line functions were fit to data from 617 southern pine poles and from 225 Douglas-fir and 57 western redcedar trees. The best estimate of geometry or shape of the outer surface of the poles was a straight line. The southern pine data along with data from 1,069 Douglas-fir poles and 1,719 western redcedar poles were further analyzed for the mean and upper and lower 95 percent tolerance intervals of the taper of the pole surfaces. There was a statistical difference in the tapers between length-class combinations in a given species, but in the final analysis all data for a species were considered as a population. Guidelines are given for updating engineering design criteria for round wood poles.
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CitationBohannan, Billy; Habermann, Hermann; Lengel, Joan E. 1974. Taper of wood poles. Gen. Tech. Rep. FPL-02. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 9 p.
KeywordsPoles, taper, geometry, strength, poles (wood), design
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