在役斜拉桥的多尺度力学特征及失效机制研究

发布时间：2018-03-01 06:15

本文关键词： 一致多尺度尖端裂纹斜拉桥静力分析损伤分析　出处：《北京建筑大学》2017年硕士论文　论文类型：学位论文

【摘要】：新经济政策以来,我国综合国力继续稳步提升。在经济增长继续利好的情况下,更加便捷的出行环境和更加丰富的交通网络成为了人民群众的主要需求之一。这一经济需要给桥梁等建筑工程领域的发展带来了新的机遇与挑战。当今桥梁工程也面向跨度更大、耗材更少的宏观目标发展,斜拉桥作为这之中主要结构形式,其技术也日趋精进。然而高速的发展也产生了不少问题,失效是其中之一。有数据统计,失效的桥梁61%以上未达设计寿命的一半。这不能不让人痛心。此外,大型土木结构的缺陷经过长期积累,还会产生极大的安全隐患,为人民群众的生活带来威胁。针对上述问题的重要性,本文运用一致多尺度有限元模拟方法,建立可以同时进行斜拉桥结构整体分析和局部细节特性分析的数值模型,并基于断裂力学理论开展关于斜拉桥在含有初始缺陷等损伤情况下的失效模式研究。本课题选取某斜拉桥为工程背景,主要内容有:(1)详细介绍了斜拉桥的发展情况,系统梳理对于大型土木结构有限元模型建立的一致多尺度方法的原理和现有研究进展,并给出了以断裂力学原理为基础的裂纹损伤失效的数学描述。(2)结合现有一致多尺度有限元模拟方法的理论及应用情况,从虚功原理出发,以多点约束方程法为研究对象,探讨多尺度有限元数值模型的新连接方式,编写相应子程序并结合算例加以验证。结果表明,新连接方式计算结果和解析解相比其误差率小于5%,实现了在保证结构整体分析和局部应力状态分析并发计算基础上的分析精度的提高。(3)利用现有商业软件ANSYS编辑裂纹尖端模型子程序,和一致多尺度数值模拟方法共同运用,选取算例进行建模,借助应力强度因子的计算解判别多尺度模拟方法和失效模式子程序同时使用的可操作性和准确性。(4)建立某斜拉桥数值模型,通过整体结构分析结果选择关键区域建立多尺度模型,详细分析了多尺度区域在不同工况下的应力分布情况。并探讨了关键区域存在初始损伤缺陷这类局部失效的情况下,该结构的损伤是否会进一步演化。
[Abstract]:Since the new economic policy, China's overall national strength has continued to improve steadily. A more convenient travel environment and a richer transportation network have become one of the main needs of the people. This economic need has brought new opportunities and challenges to the development of construction engineering such as bridges. It also faces a larger span, The technology of cable-stayed bridge, as the main structural form of the bridge, is becoming more and more sophisticated. However, there are many problems in the rapid development of cable-stayed bridge, among which failure is one of them. Failure of the bridge more than 61% less than half of the design life. This can not be sad. In addition, the defects of large civil structures have accumulated over a long period of time, but also have great safety risks. In view of the importance of the above problems, a numerical model of cable-stayed bridge structure analysis and local detail analysis can be established by using the uniform multi-scale finite element simulation method, which can be used to analyze the structure of cable-stayed bridge at the same time. Based on the theory of fracture mechanics, the failure modes of cable-stayed bridges with damage such as initial defects are studied. In this paper, a cable-stayed bridge is selected as the engineering background, the main content of which is: 1) the development of cable-stayed bridge is introduced in detail. The principle and current research progress of the uniform multi-scale method for the finite element modeling of large civil structures are systematically reviewed. The mathematical description of crack damage failure based on the principle of fracture mechanics is given. (2) combined with the theory and application of the existing uniform multi-scale finite element simulation method, based on the principle of virtual work, the multi-point constraint equation method is taken as the research object. This paper discusses the new connection method of multi-scale finite element numerical model, writes the corresponding subroutine and verifies it with an example. The results show that, Compared with the analytical solution, the error rate of the new connection method is less than 5, which can improve the accuracy of the analysis based on the analysis of the whole structure and the local stress state analysis, and make use of the existing commercial software ANSYS to edit. Crack tip model subroutine, And the uniform multi-scale numerical simulation method is used together, and a numerical example is selected to model the model. The numerical model of a cable-stayed bridge is established by means of the multi-scale simulation method of the stress intensity factor and the maneuverability and accuracy of the failure mode subroutine. The multi-scale model is established by selecting the key area from the overall structural analysis results, and the stress distribution of the multi-scale region under different working conditions is analyzed in detail, and the local failure of the critical region with initial damage defects is discussed. Whether the damage of the structure will evolve further.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.27

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