大断面横架材を有する2スパン伝統木造軸組の耐震要素配置と力学特性

Abstract

In seismic evaluation methods based on limit strength calculation, a shear force with a one-to-one correspondence with a load-bearing element is defined, and the shear force of construction only adds the restoring forces of the element. However, the specifications of traditional joints and element position may vary, and the calculation method does not depend on these specifications. Some previous studies have considered the specifications of traditional joints such as column-to-beam (Sashigamoi) joints based on element experiments and simulation analysis. However, the influence of element position on the structural properties and the behavior of traditional wooden frames with large section beams (Sashigamoi) based on multi-span frame experiments has been addressed in few studies. Japan has experienced numerous earthquakes, and there are many reports of traditional wooden structures collapsing because of earthquakes. However, many traditional wooden structures remain sound and unaffected and are extremely interesting. Evaluation of the seismic performance of such traditional wooden buildings may be significant in preventing damage to buildings and ensuring safety. Against this background, this paper presents the results of static cyclic loading tests and simulation analysis for four traditional wooden frames in order to understand the seismic performance of frames with uneven large section beams (Sashigamoi) and to clarify the influence of the beams and shapes of fitting-type joints on the behavior of the whole frame. Major findings of the present work are as follows: (1) First, static cyclic loading tests were conducted on four traditional wooden frames; the number of frame spans, the presence or absence of large section beams (Sashigamoi), and the position of beams were considered as the parameters. Two-span frames underwent column splitting or column breaking more readily and with smaller deformation than in the case of one-span frames. In addition, the shear forces exhibited directional dependence, which is attributed to the asymmetry of the frames or the shapes of the column-beam joints. (2) Second, a method for modeling traditional fitting-type joints was developed. This method can be used to analyze traditional wooden frames with large section beams (Sashigamoi). Simulation analysis results were in good agreement with the test results. (3) Finally, a parameter study about the aspect ratio of the frame, large section beam position, and beam height distance was carried out, and the restoring force was verified. The smaller the beam height distance, the smaller was the difference in the restoring force with the loading direction.