【作者】 徐宏；

【导师】 黄平明；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2008， 博士

【摘要】 拉(吊)索构件是有索桥梁结构如中、下承式拱桥和悬索桥的重要组成部分，大量事故表明，拉索的损伤通常会引起桥梁结构力学特性发生改变，进而威胁到桥梁的安全。由于有索桥梁结构的复杂性以及对在役损伤拉索研究的相对滞后，至今还没有形成较为系统的针对拉索损伤机理分析、损伤识别、损伤拉索系统力学分析及安全评估的研究方法。本文将理论分析、仿真计算及实桥算例相结合，对损伤拉索系统的静力重分布、动力损伤识别、安全性及耐久性评估等方面的关键问题进行研究。主要研究内容包括以下几个方面：(1)为了解决工程实践中短索索力测试计算难题，本文通过对拉索边界条件的合理模拟，建立了简支和固支复合边界条件下短索索力计算模型，推导了复合边界条件下短索索力计算公式，并采用Matlab程序对其进行了求解。提出了边界条件系数的概念，通过参数分析确定了影响边界条件系数的主要因素。以宜昌长江公路大桥短索测试计算为例，对比分析了简支、固支及复合边界条件下拉索索力及抗弯刚度的计算结果，验证了复合边界条件拉索索力计算方法的有效性。(2)基于限元理论与矩阵摄动理论，将吊索损伤模拟成为吊索系统的一阶摄动，从理论上分析吊索损伤后吊索系统张力向量变化的总体趋势，以某钢管混凝土系杆拱桥为工程实例建立其三维有限元模型，通过仿真计算，分析单根吊索和多根吊索损伤后全桥吊索系统的张力重分布规律及影响因素。(3)通过对拉索损伤前后结构频率变化率的分析，提出将桥梁结构频率与局部拉索索力相结合的拉索损伤快速识别方法，通过分析拉索损伤前后结构振型的变化，提出以模态振型Z坐标变化率加权积为识别指标的拉索损伤快速定位方法，通过仿真计算对两种损伤识别方法的有效性进行验证。(4)分析了丹尼尔效应引起的拉索钢丝强度衰减规律，建立了基于损伤因子的拉索强度安全评估模型，推导出功能函数的矩阵形式，依据各参数的分布特性生成随机样本，采用Monte-Carlo法对不同断丝率时拉索的强度安全性进行概率评估，提出了临界断丝数的概念，并将其应用于拉索强度安全的快速评估中。(5)根据拉索锈蚀机理及损伤演化过程，将钢丝锈蚀损伤生命周期简化为护套老化阶段、镀锌层锈蚀阶段、钢丝体均匀锈蚀与坑蚀阶段、钢丝腐蚀疲劳断裂阶段共4个阶段。在Faraday和Paris对金属腐蚀寿命研究的基础上，建立了钢丝腐蚀及腐蚀疲劳各阶段经历时间的分析模型，通过仿真计算，对钢丝锈蚀全寿命周期、各阶段经历时间所占比重进行了分析，进而对拉索的锈蚀寿命进行了近似评估。更多还原

【Abstract】 Cables （or slings） are the important parts of cable bridge structure such as long span cable-supported bridges and half-through or through arch bridges. Many accidents show that the cable damage often causes the bridge mechanical characters change, even threaten the bridge safety. Due to the complexity of cable system and the lagging study on damaged cable, there is not a systematic research for cable about mechanism analysis, damage identification, mechanic calculation and safety evaluation of damaged cable. In this paper, theoretical analysis, simulation calculation and bridge example are associated to study some key problems about static calculation, dynamic analysis and safety evaluation of damaged cable system. The main contents are as followings:（1） In order to solve the problems of short cable tension test and calculation, the analysis model of short cable is built on the basis of the reasonable simulation for the boundary conditions of cable, the calculating formula is deduced and solved by Matlab program. The concept of boundary condition coefficients is put forward and the influence factors for boundary conditions of short suspenders are determined. Moreover, YiChang Bridge as an example, the analysis results of three models are compared and analyzed to verify the availability of complex boundary conditions.（2） Based on the finite-element theory and matrix perturbation theory, sling damage is simulated as the 1^st perturbation of sling system, the general tendency of damage suspender tension is analyzed in theory. Meantime, a 3D finite-element model of a concrete-filled steel tube arch bridge is built to research the redistribution factors of cable tension about single and multi-cable damages system, some correlative conclusion is drawn.（3）According to the analysis for the change rates of cable before and after damaged, a quick damage identification method which combined the structure integral frequencies with the local cables tension, is put forward, at the meantime, a quick cable damage positioning method is presented, which the weighted products of the coordinate change rates in Z orientation are taken as the damage identify indicators. And a simulation calculation is carried out to verify their availabilities. （4） The attenuation regularities of wires intension caused by Daniel effect are analyzed, a cable safety evaluation model is built based on safety factors. And the matrix form of limited state function is built to simplify the calculation process by computer, the random samples are generated according to their distributing characters, then the Monte-Carlo method is used to assess the cable safety, then a critical number of broken wires is determined and applied to the rapid assessment of cable safety.（5） According to cable corrosion mechanism and damage evolvement process, the life cycle of corrosion cable is reduced into four stages, which includes jacket ageing stage, zinc coat corrosion stage, steel wire uniform and pitting corrosion stage and fatigue corrosion stage. Based on the research of Faraday and Paris, the time models of four stages are built, the life cycle of corrosion wire and every stage time proportion are analyzed, and the cable corrosion life is evaluated approximately.更多还原