Analytical study and finite element modelling of timber connections with glued-in rods in bending

The behaviour of glued-in ribbed steel bars in timber beam-to-beam connections has been analysed experimentally and numerically. The experimental results exhibit two different failure modes due to the internal stiffness distribution between steel and timber in bending. They are used to validate a 3D finite element model developed considering the actual geometry of the connections. This model considers the elasto-plastic behaviour of steel and the orthotropic elasto-plastic behaviour of timber. Timber plasticity is considered for compression in parallel and perpendicular to grain directions. The compression arises mainly in the local contact zone between the connected timber beams and in the vicinity of the glued-in rods. These sources of non-linearities, due to the elasto-plastic behaviour and the contact, control partially the load-carrying capacity of the connections. To take account of the quasi brittle behaviour of timber in shear and tension perpendicular to grain, a failure criterion is used. The numerical results show a good agreement with the experimental results. In addition, analytical models are proposed to predict the initial stiffness and the ultimate moment of the glued-in rods connections. The comparison of the analytical and the numerical results shows the good capability of the analytical model to be used as a design approach for the glued-in rod connections.