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Title: Strength Evaluation Of Round Timber Piles

Source: U.S. Forest Service, Forest Products Laboratory, FPL-RP-101, December 1968

Author(s): Wilkinson, T.L.

Publication Year: 1968  View PDF »

Category: Research Papers

Abstract: Foundation piles are used to support structures resting on soils having insufficient bearing strength to support footings for any but the lightest loads. Current practice is to design wood piles for loads of 15 to 25 tons when load tests are not conducted and for loads of 40 to 50 tons are justified by the load test. These higher loads produce stresses that approach the allowable stresses for green sawn timbers. Data are needed to verify that the higher design stresses are justified for timber piles. This study was conducted in two parts. In Part 1, strength properties in compression parallel to the grain and in bending were dertermined for 15 timber piles of each of 3 species-- Douglas-fir, southern pine, and red oak. The results of these evaluations indicated the following average tip end crushing strengths: read oak 3,460 p.s.i., Douglas-fir 2,960 p.s.i., and southern pine 1,820 p.s.i. The three species ranked in the same order for modulus of rupture. In Part 2, the effect of kiln-drying of southern pine piles on crushing strength was investigated. Kilndried piles had about 12 percent less crushing strength than green piles when both were evaluated at the same moisture content. The strength values obtained in this study given an indication of the loads for which timber piles may be designed. The results should be useful in the development of timber pile specifications.

Keywords: Round timber piles, strength

File size: 1,905 kb(s)

Date posted: 09/13/2010

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