Analysis of the fracture process of wooden frame structure under seismic loading by modified distinct-element method.

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This study was aimed to develop a new method, that enables to simulate the collapsing processes of wooden frame structure.Firstly, the mechanical and fractographical behaviors of the joint parts under the dynamic loading were examined by experimental studies. Tensile and shearing tests of metal-fastened joints, which are made between the column and sill / beam, were made under various loading rate from 0.2 mm/sec to 2000 mm/sec. It was found that the fracturing aspects of the joint parts were different between the slow loading case and the high speed one.Secondly, we tried to simulated the collapsing process of the frame structure in two dimensional frame models by a modified distinct element method, and we could make a program that can show the changing process of the frame from a rectangle to a parallelogram. In the next step, we developed a three dimensional program. In this program, each bar element was represented by four lows of distinct element. Composing these elements, we could arrive to analyze the collapsing process of two- story frame buildings under dynamic loading to the basement. For examples, a structure that have non-symmetric brace arrangement showed a rotating collapsing pattern, which can be observed in actual wooden house.We also made a dynamic loading experiment using a reduced scale model structure. The order that joints destroy and the process of the buildings fall down agreed well between the simulation and the experiment.We believe that our research can provide a powerful mean for the analysis of the wooden frame structure's behavior under a large scale earthquake.