正交异性钢桥面板热点应力法的疲劳寿命评估

发布时间：2018-02-02 01:18

本文关键词： 正交异性钢桥面板疲劳寿命热点应力法疲劳性能足尺模型试验　出处：《西南交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于正交异性钢桥面板结构在承载能力、跨越能力、受力性能和经济性等方面的综合优势被广泛应用于各种桥型,在表现出强大生命力的同时又因其构造复杂性、众多的交叉焊缝、由焊接残余应力和初始缺陷引起的局部应力集中导致疲劳问题突出。大致准确预测新建桥梁的疲劳寿命并判断其能否达到设计使用寿命要求,既是确保其在设计寿命期内安全性的必然要求也是疲劳设计和评估的最终目的。论文以正交异性钢桥面板U肋横隔板细节为研究对象,基于热点应力法计算其疲劳寿命,通过进行足尺模型试验以实测数据进行验证并建立足尺试验模型的有限元模型,通过名义应力法、热点应力法分别进行有限元计算来证明热点应力法进行疲劳寿命评估的有效性和可行性,在对正交异性钢桥面板等复杂结构的疲劳评估上相对于名义应力法的优越性。主要做的工作如下：(1)概述了正交异性钢桥面板结构的发展历程、应用现状、结构特点和受力特征,简述了疲劳、正交异性钢桥面板疲劳问题和热点应力法在钢桥疲劳研究中的的发展历程和应用现状；(2)简述了正交异性钢桥面板结构疲劳分析的基本理论和相关基本概念,总结了当前阶段几种主要的疲劳寿命评估方法；(3)详细介绍了热点应力法的基本原理,通过有限元方法和子模型技术研究了热点应力值对单元类型、网格尺寸、外推方法等相关参数的敏感性；(4)以港珠澳大桥为工程背景,根据既有交通量调查报告推算出标准疲劳车荷载模型,建立对应有限元模型,通过有限元计算确定要研究最不利细节-U肋横隔板焊趾处及对应的最不利加载工况,在对应位置加载后结合循环计数法得到其应力谱,基于热点应力法S-N曲线及Miner准则,估算其疲劳寿命为129.13年；(5)通过对该桥进行足尺模型试验并建立对应有限元模型来验证基于热点应力法计算疲劳寿命的准确性,能够满足120年使用寿命的设计要求及热点应力法进行疲劳寿命评估的有效性和优越性。足尺模型试验的设计原则、设计方案、加载方案、测试方案及足尺模型试验有效性的验证可以为以后相关类似试验提供参考和借鉴。
[Abstract]:Due to the comprehensive advantages of orthotropic steel bridge slab structure in bearing capacity, span capacity, mechanical performance and economy, etc., it has been widely used in various bridge types. At the same time, because of the complexity of its structure, there are many cross welds. The local stress concentration caused by welding residual stress and initial defect causes the fatigue problem to be prominent. The fatigue life of the newly built bridge is predicted accurately and whether the fatigue life of the new bridge can meet the design service life requirement can be judged. It is not only the necessary requirement to ensure the safety in the design life but also the ultimate purpose of fatigue design and evaluation. This paper takes the details of U-ribbed transverse diaphragm of orthotropic steel bridge as the research object. Based on the hot stress method, the fatigue life is calculated, the finite element model of the full-scale test model is established by the full-scale model test and the finite element model of the full-scale test model is established, and the nominal stress method is adopted. The hot-spot stress method is calculated by finite element method to prove the validity and feasibility of the hot-spot stress method in fatigue life evaluation. In the fatigue evaluation of orthotropic steel deck slab and other complex structures, compared with the nominal stress method, the main work is as follows: 1) the development history and application status of orthotropic steel bridge slab structure are summarized. In this paper, the development and application of fatigue, orthotropic steel bridge slab fatigue and hot spot stress method in fatigue research of steel bridges are briefly described. (2) the basic theory and related basic concepts of fatigue analysis of orthotropic steel bridge slab structure are briefly described, and several main fatigue life evaluation methods at present stage are summarized. (3) the basic principle of hot spot stress method is introduced in detail. The sensitivity of hot spot stress value to element type, mesh size and extrapolation method is studied by finite element method and submodel technique. Taking HongKong-Zhuhai-Macao Bridge as the engineering background, the standard fatigue vehicle load model is deduced according to the existing traffic volume investigation report, and the corresponding finite element model is established. It is determined by finite element calculation to study the most unfavorable details-U rib transverse diaphragm welding toe and the corresponding most unfavorable loading conditions. After loading in the corresponding position combined with the cyclic counting method to obtain its stress spectrum. Based on the S-N curve of hot spot stress method and Miner criterion, its fatigue life is estimated to be 129.13 years. 5) the accuracy of calculating fatigue life based on hot spot stress method is verified by the full-scale model test and the corresponding finite element model of the bridge. It can meet the design requirements of 120 years of service life and the validity and superiority of hot stress method in fatigue life evaluation. Design principle, design scheme and loading scheme of full-scale model test. The validity of the test scheme and full-scale model test can be used as reference for similar experiments in the future.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.31;U441.4

【参考文献】