在役公路钢桥疲劳性能及剩余寿命评估

发布时间：2018-06-28 17:34

本文选题：高周低频 + AASHTO规范　；参考：《重庆交通大学》2015年硕士论文

【摘要】：近年来,随着我国经济的发展,城市交通量的增加,许多建国初期建设的钢桥在现有交通条件下每天都在承受着高周低频的荷载作用,本文运用疲劳寿命评估方法,对我国目前钢桥疲劳进行研究,并以重庆嘉陵江牛角沱大桥(钢桁架)为工程实例进行具体研究,研究的工作及结论如下:(1)在公路钢桥抗疲劳设计理论中指出了无限寿命设计要求将构件中的使用应力控制在很低的水平,材料的特性并不能完全的体现,无限寿命不经济;安全寿命设计采用S-N曲线下降段,基于Miner累积损伤理论而来,目前被广泛使用;损伤容限设计承认结构存在原始缺陷,比较贴近真实情况。(2)对公路钢桥疲劳性能的研究,并结合国外的规范(AASHTO、Eurocode),通过对比分析,得出我国公路钢桥规范的优缺点。Eurocode分级比较均匀,而AASHTO分级比较细,从AASHTO之中可以看到A级细节与E'级细节容许应力幅值相差147.1MPa,各级疲劳细节区分明显,便于计算疲劳寿命,这一点给了我们在制定疲劳规范时很好的借鉴。(3)利用有限元建立重庆嘉陵江牛角沱大桥的三维模型,通过受拉构件的最大应力幅值确定大桥的易损部位。(4)采用有限元,对重庆嘉陵江牛角沱大桥易损部位进行局部模拟,得到大桥在静力荷载作用下抗疲劳性能良好。(5)调查实桥交通荷载,运用Monte—Carlo法模拟实际车流,采用影响线加载,运用雨流计数法进行计数统计,获取构件的模拟应力谱,然后采用传统疲劳寿命评估方法计算重庆嘉陵江牛角沱大桥易损构件的剩余疲劳寿命。
[Abstract]:In recent years, with the development of our economy and the increase of urban traffic volume, many steel bridges built in the early days of the founding of the people's Republic of China are subjected to high cycle and low frequency loads every day under the existing traffic conditions. In this paper, the fatigue life assessment method is used. This paper studies the fatigue of steel bridges in China, and takes Niujiaotuo Bridge (steel truss) in Chongqing Jialing River as an engineering example. The research works and conclusions are as follows: (1) in the theory of anti-fatigue design of highway steel bridges, it is pointed out that the infinite life design requires that the use stress in the components should be controlled at a very low level, the characteristics of the material can not be fully reflected, and the infinite life is not economical; The safety life design is based on Miner cumulative damage theory and S-N curve descending section. The damage tolerance design admits that the structure has original defects, which is close to the real situation. (2) the fatigue performance of highway steel bridges is studied. By comparing and analyzing the AASHTO Eurocode, it is concluded that the advantages and disadvantages of our country's highway steel bridge code are uniform, while the AASHTO classification is fine. It can be seen from the AASHTO that the difference between the allowable stress amplitude of A level and E 'level detail is 147.1 MPa. The fatigue details of each level are distinguished obviously, and it is convenient to calculate fatigue life. This gives us a good reference in the formulation of fatigue code. (3) using finite element method to establish the three-dimensional model of Niujiaotuo Bridge in Jialing River, Chongqing, and determine the vulnerable position of the bridge through the maximum stress amplitude of the tensile member. (4) finite element method is used. The local simulation of the vulnerable parts of Niujiaotuo Bridge in Jialing River, Chongqing, shows that the fatigue resistance of the bridge is good under static load. (5) the traffic load of the bridge is investigated, the actual traffic flow is simulated by Monte-Carlo method, and the influence line is used to load the bridge. The simulated stress spectrum is obtained by using rain flow counting method, and then the residual fatigue life of vulnerable members of Niujiaotuo Bridge in Jialing River in Chongqing is calculated by traditional fatigue life evaluation method.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4

【参考文献】