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Abstract
This study presents a comparative evaluation of semi-destructive and destructive testing of wood. Semi-destructive methods are represented by screw-withdrawal test, microdrilling, pin penetration and a new construction of a diagnostic device for in situ evaluation of timber based on the principle of measuring the mechanical resistance to pin being pushed gradually into wood. In order to ascertain the differences between the methods, measuring of three basic softwood species was conducted. One of the aims was to capture the variability of properties brought about by the distribution of properties along the diameter and along the trunk (section) length; therefore, an entire trunk of spruce, fir and pine were used for testing. The accuracy of the prediction of mechanical properties provided by the semi-destructive devices was verified using correlations with mechanical properties established by standard pressure tests in compliance with European norms. The results show a very good correlation of the mean force necessary to push the pin in the timber with wood density and strength in compression along the grain found in standard specimens.[PUBLICATION ABSTRACT]