High capacity timber joints : Proposal of the shear plate dowel joint

Sammanfattning: An increased use of wood can reduce the environmental footprint of the building sector by being a renewable and ecological material. In order to improve the competitiveness of heavy timber structures, this thesis presents a novel type of timber connection with a high degree of prefabrication, which utilizes a resilient bond line.It has previously been shown that a large conventional stiff adhesive bond line acting in shear can be made stronger by using a less stiff bond line, by e.g. introducing an intermediate rubber foil. The scientific contribution of this thesis starts by comparing such resilient bond lines to conventional non-resilient bond lines. It is numerically shown that the strength of the bond line is increased from 40% to 80% of the local shear strength by introducing a resilient bond line in large lap joints. Unlike other types of connections, a resilient bond line enables design of the stiffness depending on the application by varying the hardness and thickness of the intermediate bond layer.Using the concept of the resilient bond line in a heavy timber connection design aiming for a high degree of prefabrication, the novel Shear Plate Dowel Joint (SPDJ) is proposed. Initially designed for truss nodes, the connection shows promising results in full scale tensile tests with an average shear stress at failure of 3.3 MPa. A bond line model to be used in FE analysis of the SPDJ is proposed and used in parameter studies of the connection. It is found that a softer bond line will increase the slip, but also the strength which asymptotically aligns with theory of perfect plasticity.The strengths of the SPDJ design are high load carrying capacity and simplicity in design, but duration of load effects and fire resistance are, among other things, in need of further research prior to structural application.