Strength grading of timber in Europe with regard to different grading methods

Strength grading of timber in Europe with regard to different grading methods

Stapel, P.
Van de Kuilen, J.W.G.

Civil Engineering and Geosciences

Structural Engineering

2014-08-10

Structural timber in Europe is either graded visually or by machine. Both grading methods are applied to limit the variation in engineering properties of sawn timber. The obtained grading results are largely dependent on the method chosen. In addition, parameters such as species, source, and cross-section of the timber, as well as the applied grading rules also play a role. To what extent these parameters - depending on the chosen grading method - actually affect timber properties and yields is of interest for both producers and users of sawn timber. For analysing the different grading results, laboratory data of 10704 spruce specimens were evaluated. The used cross-section has a major influence on the grading result. Furthermore, the used grading rule and the method applied to determine characteristic values are essential for the grading result. The origin of the timber influences the grading results of both grading methods. While the yields for machine grading are always higher than for visual grading, both grading methods are prone to fall short of the declared properties. It is recommended to adjust the normative framework as well as to regulate both grading procedures similarly.

visual grading
machine grading
growth areas
test procedures

http://resolver.tudelft.nl/uuid:b1852723-e20a-4b2c-9a01-bbdd282bf392

978-0-86488-559-3

WCTE 2014: Proceedings of the World Conference on Timber Engineering, Quebec, Canada, 10-14 August 2014

Institutional Repository

conference paper

(c) 2014 The Author(s)