Densified wood dowel reinforcement of timber perpendicular to the grain: a pilot study

An investigation was carried out to examine the potential to utilise densified wood dowels as a reinforcement for timber subjected to compression loading perpendicular to the grain. While timber has a high strength-to-weight ratio parallel to the grain, it demonstrates poor strength perpendicular to the grain and in recent years there has been a significant number of studies examining the use of steel screws and bonded-in rods as reinforcement in this area. This is becoming more and more important with the increased use of timber in medium-to-high rise structures. In this study, thermo-mechanical densified wood in the form of dowels are utilised as compression reinforcement perpendicular to the grain and tested to failure. Thermo-mechanically densified dowel reinforcement arrangements of 2, 4, and 6 dowels are examined experimentally under a compressive load and compared to timber samples similarly reinforced but with steel self-tapping screws. The results have demonstrated the potential to utilised densified wood to create an all-wood solution to reinforce against compressive stresses perpendicular to the grain. Additionally, modifications to recently proposed Eurocode 5 recommendations for the design of compression reinforcement using self-tapping steel screws are presented, which are suitable for the design of compression reinforcement using densified wood dowels.