Characterization And Grading Of Some Potential Timber Based On EN-338(2009
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Date
2020-08
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Addis Ababa University
Abstract
The paper is aimed at the characterization and grading of two potential timbers species in
Ethiopia using EN-338 (2009) strength classification for Euro code 5 timber design. The
timber species namely Cupressus lusitanica mill and Eucalyptus globulus labill were
obtained from Gullele Botanic Garden (GBG). Physical and mechanical properties of the
selected timber species were determined in according with EN 13183-1 (2002), EN-373
(1957) and EN 408(1995) on small clear specimens. Three point bending tests based on
EN 373 (1957) with specimen size 2x2x38 cm was carried out using a universal testing
machine (UTM). Mechanical properties of timbers such as bending strength, modules of
elasticity and compressive strength of each timber species were determined. Strength
grading of timber species was conducted by adjusting the material property value at 12
% moisture content equivalent.
Forty five samples from each species, 15 sample from bottom, 15 from middle and 15
from top for each species were tested.
Compression stress parallel to the grain samples were prepared and tested. The
experimental results were compared with the analytical values. The analytical
compressive strength value was derived by the formula from EN-338 and these values
were used to verify the test results.
Finally, the timber species were then graded according to EN 338 (2009). And hence
Cupressus lusitanica mill and Eucalyptus globulus labill were assigned to C-16 and D-24
class, respectively.
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Keywords
Timber, EN-338(2009)