Present and Future Tasks for Screw Joints in Timber Structures

Various kinds of screws are used for timber structures and they will become more and more popular fasteners in the future. In this article, I reviewed some domestic and international codes, standards and researches. Screws are dowel type fasteners such as nails, bolts, and so on. Therefore, shear performance of screw joints can be calculated from common theory. Furthermore, withdrawal strength of screw is much higher than that of other fasteners. Thus it is possible to consider the load increase as a “rope effect”, to design inclined screw joints for expected withdrawal capacity, and to use screws as timber reinforcement assemblies. Changing domestic codes, making standards more effective and evaluating long term behavior of screw joints will be future tasks.