Strength and Related Properties of Knobcone Pine

Arno P. Schniewind, Barry W. Gammon

Abstract


The mechanical properties of knobcone pine (Pinus attenuata Lemm.) were evaluated using the second 8-ft log from the butt of ten trees selected from a stand in Siskiyou County, California. The trees, averaging 71 ft in height and 14 in. dbh, had a growth rate of 12 rings per inch at the stump and a specific gravity of 0.38, based on green volume and oven-dry mass. Specimens were selected and tested in accordance with ASTM D143-52 in both green and air-dry conditions. Adjusted to 12% moisture content, knobcone pine has a modulus of rupture and modulus of elasticity in static bending of 10,800 psi and 1,500,000 psi, respectively, a maximum crushing strength parallel-to-grain of 5,640 psi, and a shear strength parallel-to-grain of 980 psi. These results show that knobcone pine is similar to ponderosa pine in strength and stiffness.

Keywords


Pinus attenuata;mechanical properties;static bending;compression parallel-to-grain;compression perpendicular-to-grain;tension parallel-to-grain;toughness;shear;cleavage;modulus of rupture;modulus of elasticity;hardness;shrinkage;specific gravity

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