EVALUATION OF WITHDRAWAL STRENGTH OF SELF-TAPPING SCREW INSERTED INTO CROSS-LAMINATED TIMBER WITH DIFFERENT ANATOMICAL ASPECTS

The use of cross -laminated timber (CLT) technology is witnessing an upsurge in Japan because of its satisfactory performance under seismic conditions. The withdrawal strength ( f(ax)) of a single self -tapping screw (STS) inserted into the CLT was observed using a withdrawal test. The experimental results showed that f(ax) of the partially threaded STS was higher than that of the fully threaded STS when inserted perpendicular to the grain. The empirical model used to predict f(ax )provided in the European standard for the design of timber structures was evaluated by comparing the predicted values with the experimental results, which showed that the empirical model was only suitable for predicting the withdrawal strength of specimens with STSs inserted perpendicular to the grain. Therefore, a new probabilistic model was proposed for specimens inserted with STSs inserted parallel to the grain. The failure modes with respect to the orthotropic anatomy of wood materials were observed.