On the embedment and semi-rigid behaviour of tab-and-slot joints in rotational partial compression

When submitted to partial compression perpendicular to the grain, a wood element deforms. This embedment mechanism is the cause of the semi-rigid moment-resisting behaviour of joints in rotation. Modelizing this deformation is very important to evaluate the structural response of timber constructions to external and internal actions. It has been observed that, in addition to a directly loaded volume deformation, an additional indirectly loaded deformation develops, resulting in an additional strength of wood in compression perpendicular to the grain. Based on a litterature review and a semi-empirical analysis of deformed LVL Kerto-Q Tab-and-Slot joints, the additional deformation in rotational partial compression has been attributed an exponential-root profile f(x) = A.exp(−Bx) and the values for the parameters A and B have been evaluated for different joint-configurations, depending on the grain direction and thickness of the joint. Moreover, while modelizing wood as a bilinear material, the yield rotation-angle, defined as the limit angle between an elastic and plastic response of a joint in rotation, has been defined in this paper for the different joint-configurations. The results of this thesis are aimed to be implemented in the analytical model of volume deformations in rotational partial compression developed by S. Roche in his Ph. D. thesis in order to modelize the semi-rigid moment-resisting behaviour of Multiple Tab-and-Slot joints in timber plate structure. This model is a potential candidate to be incorporated in future structural timber design standards