Modified traditional Japanese timber joint system with retrofitting abilities

Embedment is a key feature of timber joints envisioned as the ultimate solution in avoiding the devastating full collapse of timber structures in seismic countries. The Japanese traditional timber post-and-beam structural system utilizes moment-resisting joints based on embedment. Despite the joint's advantages having the ductile and energy-absorptive behavior continuously to the post-elastic phases, a primary shortcoming needs to be resolved - specifically of having the low and unreliable initial stiffness due to the gap formation between the contacting members. Further, large-dimensioned timber most suitable for the embedment-type joint is scarce and the lower quality of available timbers is making the modern applications difficult. A new timber joint capable of sustaining future seismic impacts is being pursued using various approaches. As a result of the optimization to satisfy the manifold studies, two traditional elements, namely Kusabi wedge and side-penetrating Nageshi beam, are combined and tightened by the penetrating steel bolt. Its tightening system eliminates the gap formation in the joint, and heightens its performance over the traditional embedment-type joints. Additional features, such as the damage-inducing and fast seismic-retrofitting ability, are also integrated. This new proposal for the Kusabi-Nageshi (K-N) timber joint system aims to provide a new alternative to the joints used in seismic countries.