A comparison of bending strength and modulus of elasticity (MOE) of squares with wanes to round timber was performed as part of a project on the use of round Scots pine (Pinus sylvestris L.) timber in structural frameworks. The study was based on 125 squares and 124 round logs from two sites at high altitudes and two sites at low altitudes in southern Norway. The effects of wanes were estimated by means of reduction in second moment of area and section modulus. Wanes had significant effect on both bending strength and MOE, but in both cases the effects were minor when compared with the effects of material properties. The reduction of bending stiffness due to wanes was almost as much as expected from lack of section, while the reduction of moment capacity was smaller. Squares with ⅓ wane had both lower bending strength and lower MOE than round timber. According to how bending strength and MOE are calculated, differences due to wane were expected. The observed difference in bending strength was larger than expected through the lack of section, indicating that it was affected by material properties as well. The difference in MOE between round timber and squares with ⅓ wane could be explained by the lack of section according to how these values are calculated. Origin had a significant effect on both bending strength and MOE.
Contributor Notes
The authors are Associate Professors, Norwegian Univ. of Life Sciences (UMB), Dept. of Ecology and Natural Resource Management, NO-1432 Ås, Norway (geir.vestol@umb.no, olav.hoibo@umb.no). This paper was received for publication in June 2009. Article no. 10643.