NUKI-TO-COLUMN JOINTS USING WEDGE CONTROLLED WITH SPRINGS FOR JAPANESE TRADITIONAL WOODEN FRAMES

Abstract

 The authors’ previous studies on the structural characteristics of Nuki-to-column joints using wedges for Japanese traditional wooden frames showed that the problem with such joints is the extraction of wedges due to cyclic loading. This paper proposes a joint with a spring device to solve this problem. The proposed joint maintains the embedment characteristics of joints at all times and retains the advantages of conventional Nuki-to-column joints. The proposed joint is a Nuki-to-column joint with a spring device attached to the wedge of the traditional joint.

 We show the superiority of the proposed joint through full-scale and element tests, and demonstrate the possibility of practical application.

 Chapter 1 describes the significance of this study.

 Chapter 2 outlines the problem with the traditional joint and describes the proposed joint.

 Chapter 3 shows the structural characteristics of the proposed joint through full-scale tests and demonstrates the superiority of the joint.

 Chapter 4 shows the results of element tests that were conducted to examine the proposed spring device in detail. Furthermore, a method for determining the hysteretic characteristics of the joint based on element tests is demonstrated.

 Chapter 5 shows the superiority of the proposed joint using evaluations of energy absorption and time history response displacement.

 The following conclusions were obtained in this study:

 1) Through full-scale and element tests, this study showed that the parameters for the proposed joint are wedge type, spring constant, tree species, and wedge angle.

 2) The bending moment, stiffness, and bilinear hysteresis for the proposed joint were compared with those for a conventional joint. A method for determining the hysteretic characteristics of the joint based on element tests was demonstrated.

 3) A hysteretic model for the proposed joint was proposed for time history response analysis based on a bilinear-slip model.

 4) The proposed joint showed higher energy absorption performance than that for a conventional joint. The time history response analysis showed that the maximum response for the proposed joint was less than half that for the conventional joint.