InTrans / Aug 14, 2018

Densified Veneer Wood Reinforced Timber Joints with Expanded Tube Fasteners

The objective of the study is to assess the properties of a completely new type of timber joint. The novel joint has mechanical properties which are superior compared to all other existing mechanical timber joints. This is achieved by local reinforcement of the jointed area with densified veneer wood (dvw) and by using a new type of dowel fastener. A tube is fitted into over-size holes and expanded in diameter after assembly of the joint components. The high embedment strength of the dvw enhances the strength. The diameter expansion of the tube fastener results in no hole clearance and an immediate load take-up.
The main part of the study consists of experiments to assess the relevant mechanical properties of dvw and to determine minimum end and edge distance of the tube fastener in relation to the dvw thickness. Pseudo-dynamic tests are performed to show the unique ductility and energy absorption capacity. Simple strength and stiffness models are presented and validated. Proposals for design rules are given. Finally, a number of timber structures are designed using traditional dowel type fasteners and compared with the application of the new joint. It is shown that timber savings of 40% can be achieved.