wood protection by design

WOOD PROTECTION BY DESIGN –
CONCEPTS FOR DURABLE TIMBER BRIDGES
Brischke, C. 1 , Meyer-Veltrup, L. 2 , Thelandersson, S. 3 , Malo, K.A. 4
ABSTRACT
Various abiotic and biotic agents have a negative effect on the service life of materials
used for bridge constructions. Corrosion of steel, carbonization of concrete and decay of
timber are limiting their service lives. It is a common perception that the expected
lifetime of a timber structure is only a fraction of that of a concrete or steel structure. In
spite of this there are numerous timber structures remaining since centuries such as
Norwegian stave churches, half-timbered oak houses, and covered bridges in
Switzerland – commonly accepted as consequence of proper design and workmanship.
In contrast, many untreated timber structures show severe decay after only a few years
in service due to wetting.
The WoodWisdomNet research project DuraTB (‘Durable Timber Bridges’) aims
therefore to significantly improve the durability of timber bridges. A modern and
innovative concept is sought to provide design solutions being among the best
alternatives with respect to environmental friendliness, initial and life-cycle costs,
showing excellent results in life-cycle analyses.
The paper gives an overview about objectives and research activities of the project.
Work on the development of performance and climate models performed at Lund
University, Sweden, and Leibniz University Hannover, Germany, are presented in the
latter part of the paper. Various details were evaluated regarding their moisture-induced
risk for decay, which was identified as key element for service life prediction of bridge
structures in the absence of chemical wood preservation.
Key words: Decay modelling, glulam, moisture risk, Network arch bridge, Norway
spruce
1 Leibniz University Hannover, Faculty of Architecture and Landscape Sciences, Institute of Vocational
Sciences in the Building Trade, Herrenhäuser Str. 8, D-30419 Hannover, Germany, Tel: +49 511 762
5829, E-mail: brischke@ibw.uni-hannover.de
2 Leibniz University Hannover, Faculty of Architecture and Landscape Sciences, Institute of Vocational
Sciences in the Building Trade, Herrenhäuser Str. 8, D-30419 Hannover, Germany, Tel: +49 511 762
4598, E-mail: meyer@ibw.uni-hannover.de
3 Lund University, Division of Structural Engineering, Box 118, Paradisgatan 5c, SE 22100 Lund,
Sweden, Tel: +46 46 222 4885, E-mail: thelandersson@kstr.lth.se
4 Norwegian University of Science and Technology, NTNU, Department of Structural Engineering, Rich.
Birkelandsv 1a, NO-7491 Trondheim, Norway, Tel: +47 7359 4784, E-mail: kjell.malo@ntnu.no