Optimisation of pre/post-stressed embedment-type timber joint Available to Purchase

This paper analyses the optimisation studies of a pre-stressed embedment-type timber joint system, the Kusabi–Nageshi (K–N) timber joint system, designed to be used for structures in seismic-prone countries. The K–N joint is composed of a triangular-sectioned beam and wedges in combination with bolts. Its resistive mechanism utilises the embedment strength of timber and the pre-stress in association with friction. In addition, elastic energy deposited in the bolt as storage fills the gap as it is deformed during the embedment. With the aim of optimising both mechanically and physically, several alterations were tested in terms of shape (taper angle) and of combining densified veneer wood (DVW) with the joint members. A cyclic loading test of the cross joints was made to examine their structural behaviour. The use of less tapered wedges showed higher stiffness and strength, but the beam beneath was undesirably embedded. Different combinations of reinforcement with densified veneer wood showed that the use of the wedges alone provided high optimisation, and an increase in bolt axial force. The successful test results observed in the alteration using the densified veneer wood are expressed using the ‘analytical K–N joint diagram', an analytical method modified from a conventional joint diagram used in mechanical engineering, which showed itself to be an applicable method to predict the trend of the altered K–N joint. The use of the new tapered angle and densified veneer wood for optimisation, and the performance predictions using the analytical K–N joint diagram, will need further precise investigations but their great benefits are potentially promising.