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

改进离散元法分析地震作用下木框架结构的断裂过程

• 批准号: 09460072
• 负责人: OHTA Masamitsu
• 金额: $ 9.02万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09460072/
• 关键词: dynamic loading; wooden frame structure; metal-fastened joint; fracture aspect; Modified Distinct Element Method; Three-dimensional simulation; collapsing process; model used experiment; 3次元シュミレーション; 筋交い; 非対称構造; 枠構造; 破壊過程; シミュレーション; 非連続体解析 /

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.

本研究旨在开发一种新的方法，能够模拟木框架结构的倒塌过程。首先，通过实验研究了在动态载荷作用下，连接部位的力学行为和断口形貌。在0.2 ~ 2000 mm/s的不同加载速率下，对柱与梁、梁之间的金属连接节点进行了拉伸和剪切试验。其次，本文尝试用改进的离散元法模拟二维框架结构的倒塌过程，并编制了程序，可以显示框架从矩形到矩形的变形过程。在接下来的步骤中，我们开发了一个三维程序。在这个程序中，每个酒吧元素由四个不同的元素表示。将这些单元组合起来，就可以分析地下室在动荷载作用下两层框架结构的倒塌过程。例如，一个非对称支撑布置的结构表现出旋转倒塌的模式，这可以在实际的木制房屋中观察到。我们还进行了动力加载实验，使用缩小的模型结构。模拟结果与试验结果吻合较好，节点破坏顺序和房屋倒塌过程基本一致，为分析木框架结构在大震作用下的受力性能提供了有力的手段。