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A Study on Fatigue Evaluation Procedure for Steel Bridge Members

钢桥梁构件疲劳评估程序的研究

基本信息

批准号：
03650387
负责人：
MORI Takeshi
金额：
$ 1.09万
依托单位：
Hosei University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Fatigue design load, design stress range histogram, fatigue strength evaluation procedure, and interactive program for fatigue evaluation are investigated in order to construct fatigue evaluation procedure for steel bridge members. This study summarized as follows.Stress variation analyses with the aid of influence line and Monte Calro simulation of traffic flow are performed under usual traffic condition. On the basis of the analytical results, the fatigue design stress range histogram for highway bridges are proposed. Proposed fatigue design load is the three axles truck of 20tf weight and the design histogram is to utilize two-parameter Weibul distribution.Fatigue crack propagation analyses for typical structural details are performed under many types of variable-amplitude stresses which approximately express the stresses in various steel structures. On the basis of analytical results, the relationship between threshold stress range to give the fatigue damage and the degree of fatigue damage is verified. By combining the relationship with the linear damage conception, a new procedure is proposed to predict the fatigue life of the structural details under variable-amplitude stresses.An interactive program has been developed for checking the safety of steel highway bridges against fatigue, and estimating fatigue life and remaining life easily. This program consist of three subprograms. The first is that analyze the stress variations caused by passing of various vehicles, the second is that determine allowable stress range based on the Recommendations for Fatigue Design Method of Japanese Society of Steel Construction, and the last is that check the safety by comparison of the stress variation to the allowable stress range.

研究了钢桥构件的疲劳设计载荷、设计应力幅直方图、疲劳强度评估程序和交互式疲劳评估程序，以构建钢桥构件的疲劳评估程序。主要研究内容如下：在正常交通条件下，利用影响线进行应力变化分析，并对交通流进行蒙特卡罗模拟。在此基础上，提出了公路桥梁疲劳设计应力幅直方图。建议的疲劳设计载荷为20 tf的三轴载重汽车，设计直方图采用双参数威布尔分布，对典型结构细节进行了多种变幅应力下的疲劳裂纹扩展分析，这些变幅应力近似表达了各种钢结构的应力。在此基础上，验证了疲劳损伤阈值应力范围与疲劳损伤程度之间的关系。将该关系与线性损伤概念相结合，提出了一种预测变幅应力下结构细节疲劳寿命的新方法，并开发了交互式程序，可以方便地进行公路钢桥疲劳安全性校核、疲劳寿命和剩余寿命估算。该程序由三个子程序组成。首先分析各种车辆通过时引起的应力变化，其次根据日本钢结构学会疲劳设计方法建议确定容许应力范围，最后通过应力变化与容许应力范围的比较来检查安全性。