Analysis and test of stiffness of bolted connections in timber structures

The stiffness of bolted connections in timber structures is of particular importance in the evaluation of the lateral performance, yet the method to calculate the stiffness of connections remains largely unsolved. To facilitate evaluation of the stiffness of bolted connections, testing of the dowel-bearing performance of wood and the lateral performance of bolted connections were revisited. In addition, experimental evaluation of the moment-resisting performance of beam-column joints with bolted connections was conducted in this study. Three deformation modes, namely Pre-Yield Modes I, Ⅱ and III, in relation to the European Yield Modes were identified. Empirical formulae for calculating dowel-bearing stiffness both parallel and perpendicular to grain were obtained via regression of the dowel-bearing test results. By making simplifications to the beam-on-elastic-foundation theory to suit a particular bolted connection, formulae with respect to the Pre-Yield Modes for calculating the stiffness of bolted connections were derived. All formulae were validated by physical testing of both bolted connections and beam-column joints. Thus a reliable method to calculate the stiffness of bolted connections was established, making it feasible to predict the lateral performance of timber structures with bolted connections.