Research on traditional corner carpentry joints of log walls - experimental and numerical analysis including friction and individual log dimensions

The present studies are devoted to analysing carpentry corner log joints commonly used in log wall buildings in Eastern Europe and other parts of the world. The paper is focused on numerical analysis and experimental stiffness and load-bearing capacity tests of saddle-notch and dovetail corner joints. The solid model of element connections was applied in the Finite Element Method part. The real log dimensions and friction between the separate logs were considered in static nonlinear analysis. Five samples of each type of joint were tested on the experimental set-up. In each case, the humidity and density of the wood were measured, and the material properties of the pine wood were obtained based on the laboratory test and literature. A comparison was conducted between the mechanical responses of two types of tested log joints and between the failure modes. Based on the experimental tests, it can be concluded that the stiffness of the dovetail corner joints was at least four times lower in comparison to the stiffness of the saddle-notch joints. In each case, the four times higher loading magnitudes were obtained for the saddle-notch joints for the same displacement level, and the ultimate loading is two times higher. Furthermore, the dovetail corner joint finite element model requires exact dimensions of each log, in opposite to saddle-notch logs, where general dimensions are good enough to obtain a relatively good correlation of experiments and numerical calculations. • Laboratory tests on two kinds of carpentry corner joints have been made. • The exact finite element model of each joint’s log has been created. • Finite element geometrically and physically non-linear calculations including contact with friction effect have been made. • Results of laboratory experiments and FEM calculations have been compared. • A good correlation between numerical and laboratory tests has been obtained due to proposed improvements.