Mechanical Performance of Timber-to-Timber Joints with Densified Wood Dowels

The wooden peg made of hardwood is one of the oldest fasteners. However, the relatively poor mechanical properties (strength and ductility) compared with steel restrict their applications in modern timber construction. Through densification, low-density species can be used as an alternative to hardwood, with even higher mechanical properties than those of hardwood. In this study, poplar was densified with alkali pretreatment to produce the densified wood (DW) dowels. The bending and shear properties of DW dowels were estimated, and the mechanical behavior of timber-to-timber joints with DW dowels was tested to present favorable mechanical performance, including load capacity, stiffness, and ductility. The tight-fitting of dried DW dowel due to the hygroscopic swelling contributes to the rope effect, which significantly improves the ultimate load-carrying capacity of timber joints. This study confirmed that DW dowels as environmentally friendly products can be promising fastener alternatives to steel fasteners to develop more sustainable timber structures.