STRENGTH DETERMINATION OF AGED WOOD, FROM 1250AD TO PRESENT, WITH NON-DESTRUCTIVE AND SEMI- DESTRUCTIVE TEST METHODS

摘要

To what extent is there a change in the strength of wood over the course of centuries, when installed under a constant load? Are there non-destructive measurement methods for the determination of strength that are suitable for this? These two questions were the starting point of this research project. Through experience (different research results report the influence) we learned that the strength of wood is associated with the growth regions and climatic conditions in which it is located. For example, over the course of centuries in the valley of Passeier in South Tyrol (Italy), there were clearly defined areas of which we know that wood was used from their local environment in the construction of their buildings. Another decisive factor for the selection of this region was that the buildings had been dated with dendrochronological methods. This created a unique situation in that the strength of the buildings made of local wood for about nine centuries (1250 to present) could be compared and analyzed. Typical spruce and larch used in the construction local to this region were selected for the investigations. Starting with 1250AD (the oldest dated wood construction) and following in steps of 100 years, two projects (from all 18 projects) are selected and explored. Three non-destructive and respectively semi-destructive measurement methods were used for the strength testing. So the validity of the measurement systems used could be brought into relation to the actual strength, some small flawless samples from selected projects were removed and then tested in a laboratory.