Prediction of mechanical properties by means of semi-destructive methods: A review

Methods and devices for in situ establishment of mechanical properties of wood have been recently developed in cooperation with European, US and Japanese researchers. The development of these new methods was motivated by requirements from engineers who need highly accurate data of mechanical properties of specific elements to plan renovations of historic buildings. Reliable data can replace overly conservative values (usually provided by visual strength grading) in structural analysis, which allows the retention of more original material as the behavior of specific elements is safely assessed. The recently developed methods, which are described in this chapter, are tensile strength of small samples, tensile Young's modulus of mesospecimens, compression strength of cores, compression strength in a drilled hole, mechanical resistance to pin pushing, Young's modulus derived by measuring the hardness and shear strength of screw withdrawals. Although in general the devices for the testing of mechanical properties by the mentioned methods provide more accurate results than the methods used so far, they are not yet mass produced, which should change soon.