Investigation of thread configuration of self-tapping screws as reinforcement for dowel-type connection

Screw reinforcement has been applied to dowel-type connections to enhance the mechanical properties of timber as well as to reduce the risk of splitting. Studies have shown improvement in the load-carrying capacity of dowel type connections which are reinforced using self-tapping screws. However, there are many variations in forms of screw; the pilot tests for this study have shown that thread configuration can affect the effectiveness of reinforcement. Based on current knowledge, it is difficult to predict which forms of thread are more suitable and effective for reinforcement in dowel-type connections. In this paper, embedment tests have been carried out to investigate the influence of thread configurations on the performance of self-tapping screws as reinforcement. Further tests were performed to investigate whether the effect identified from the embedment tests can be applied to connections in tension. It was found that thread configuration can influence the effectiveness of screw reinforcement.