Bending strength and stiffness of aspen sawn timber

• In order to investigate the possibility of using sawn timber of European aspen (Populus tremula L.) as a structural material, 150 pieces of the dimension 45 x 120 mm2 were selected from a sawmill in the south of Sweden. The material was visually strength graded using the Nordic standard INSTA 142 and the British standard BS 4978-1996, respectively. The timber pieces were also subjected to flat-wise bending in a Cook-Bolinder Ò strength grading machine. Finally all specimens were tested in edge-wise bending according to the European testing standard EN 408. Global and local moduli of elasticity as well as bending strength were determined. The results indicate that the visual grading rules, intended for use on Norway spruce and Scots pine, seem to work fairly well on European aspen. However, grading in a flat-wise bending machine like the Cook-Bolinder seems to give a lower correlation between stiffness and strength for aspen timber than generally found for coniferous. Further, the correlation between density and bending strength was found to be very low for the aspen timber tested. It was also noticed that the aspen timber has a slightly higher bending strength and modulus of elasticity than is the case for normal qualities of Norway spruce. The study indicates that sawn timber of European aspen grown in southern Sweden can be visually graded and used as structural material.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

Nyckelord

Aspen

bending strength

modulus of elasticity

strength grading

structural timber

Construction materials

Konstruktionsmaterial

Byggteknik

Civil engineering

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