Mechanical properties of lodgepole pine: 3-inch diameter stems

A large study entitled ?Gross Characteristics of Lodgepole Pine trees in North America? (9) has been previously published. The objective of the current research study reported herein was to evaluate the mechanical properties of the 3-inch (76 mm) diameter stems of lodgepole gathered for the original study by Koch. The tree stems made available for the evaluation of mechanical properties consisted of 81 3-inch diameter at breast height (DBH) stems of latifolia and 12 3-inch DBH stems of murrayana. The properties measured for each specimen included specific gravity (SG) at 12 percent volume and ovendry weight, compression modulus of elasticity values (Ecomp) parallel to the grain, dynamic modulus of elasticity values from stress waves (ESW), and ultimate tensile strengths parallel to the grain (UTS). The conclusions from this study are that 1) for 3-inch-diameter stems that have suppressed growth, murrayana possesses significantly higher specific gravity values than latifolia; 2) low elevation latifolia possesses significantly higher values for SG, Ecomp, ESW, and UTS than high elevation latifolia; and 3) with the exception of latitude 57.5?, latitudes of 50? and above revealed a significant increase in the mechanical properties of the 3-inch stems when compared to latitudes below 50?. The major conclusion, from the standpoint of commercial value, is that 3-inch-DBH trees of latifolia that contain suppressed growth wood possess potential design values for tension parallel to grain that surpass published values for lodgepole pine. The tensile values also challenge the values for established structural species.

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