Quasi-in-situ durability tests on oak timber bridges
C Brischke, C J Behnen, M-T Lenz, K Brandt, E Melcher
This study aims on developing a method for determination of wood durability on samples taken from real structures in service. Therefore quasi-in-situ durability tests have been conducted exemplarily on timber bridges made from English oak (Quercus robur L.). Drilling cores were found to be a feasible alternative to standard specimens for laboratory durability tests against pure cultures of Basidiomycetes and against soft rot and other soil-inhabiting micro-organisms in unsterile soil. Drilling cores were therefore taken from various components of six bridges, which were similar in design, but differed in previous service life.
The determined mass losses due to fungal decay were compared with the level of damage of the studied bridge components. The results indicated that the material-inherent resistance was responsible for damages rather than poor details of the construction. The methodological approach should be seen as quasi-in-situ resistance tests providing further knowledge about the relationship of timber in service and under ideal laboratory test conditions.
Keywords: durability testing, fungal decay, drilling core, premature failure, service life prediction, test methodology