Mechanical Behavior of Timber Joints with Laterally Loaded Multiple Densified Wood Dowels under the Loading Parallel to the Grain

Aside from aesthetic appearance, recycling, ease of disassembly, decent resistance against corrosion, and no intense moisture condensing and thermal bridge, compared with steel fasteners, wooden fasteners also have the compatibility of stiffness with the assembled timber members, which reduces the risk of splitting of the assembled timber members. Due to higher mechanical properties, densified wood (DW) has become an alternative to natural wood as wooden fasteners. At present, investigations have mostly focused on timber-to-timber joints with single DW dowel, while multidowel timber joints are common in practice. In this study, the timber-to-timber joints with laterally loaded single and multiple DW dowels were tested under the loading parallel to the grain in order to explore the effects of the number of DW dowels, moisture content, and joint geometry, i.e., spacings and edge and end distances for DW dowels on mechanical behaviors of timber joints. The tests on the timber-to-timber joints with steel dowels were also performed to compare with those with DW dowels. The load-carrying capacities provided by individual DW dowels showed no reductions with the increases in the number of DW dowels and moisture content and the decrease in joint geometry. The experimental results suggest that the load-carrying capacity of multiple DW dowel joints can be estimated by using the load-carrying capacity of single DW dowel joints multiplied by the number of DW dowels in the range of joint geometries and numbers of DW dowels adopted in this study. The smaller spacings and edge and end distances for DW dowels adopted in this study than the minimum joint geometry requirements in Eurocode 5 are feasible.