Collapse loads of drift-pinned timber joints loaded perpendicular to the grain

In timber construction, connections with dowel-type fasteners such as bolts, lag screws, and drift-pins usually are used. The strength and stability of timber structures depend heavily on the fastenings that hold their parts together. Therefore, designers need to know the strength properties of connections like this. By the way, the calculated yield loads based on the European yield theory(1)) for dowel-type fasteners agree closely with the experimental results of parallel-to-grain-loadings, however, they do not coincide well with those of perpendicular-to-grain loadings.(2)) That is why a series of experimental tal studies on the strength properties of drift-pinned timber joints loaded perpendicular to the grain have been made by Kawamoto and others.(3-5)) On the other hand, it is important to predict the collapse loads of drift-pinned joints for perpendicular-to-grain loadings. Thus, in this paper, we propose the numerical analytical method. This method is the application of the Rigid Body Spring Model (RBSM), originated by Kawai.(14)) In the process of numerical analysis, the yield failure surface as shown in Fig. 2 and the stress-strain relationship as shown in Fig. 3 are used. To verify the validity of the theoretical investigation, the calculated results are compared with the experimental ones(3)) conducted with bending loads. A good correlation was demonstrated between the experimental results and the predictions of a theoretical model when the specimens satisfied the following two conditions: (1) L/d (the ratio of effective length of drift-pin to its diameter) is less than 7.6, and (2) the specimen breaks easily with horizontal splits in the timber before reaching the yield points of the drift pin joints.