跨海大桥索结构的疲劳机理研究

Tests and numerical simulation researches would be carried out to deal with the problem of cable system in the long-span bridges, which is sensitive to fatigue and brittle fracture. Firstly, the characteristic of typical traffic in the long-span bridge would be investigated. The load spectrum of total bridge could be obtained by numerical simulation. And the stress spectrums of local parts in the cable system could be also obtained. Then the fatigue performance of three special typical details in the anchor structure and the corroded cable could be studied carefully. And the influence of stress concentration caused by welding and corrosion would be discussed in details. Based on the theory of fracture mechanics, tests and numerical simulation researches would be carried out to analyses the stress concentration factor, stress intensity factor and its amplification coefficient and the cracking toughness of three special typical details in the anchor structure. The analysis would be performed on the phenomenon of stress concentration of the local corroded steel wire and its influence on macroscopic fatigue performance of the cable. Considering the different design lives of the parts of cable system and the randomness and uncertainty of the parameters, the reliability analysis and safety evaluation of the cable system could be taken to provide technical support for fatigue design code of the details.

针对大跨度索桥中索系统疲劳、脆断敏感的问题，开展对应的数值模拟和试验研究。调研大跨度索桥的典型疲劳车特点，通过数值模拟提出跨海索桥的载荷谱，研究索系统中各部分结构的局部应力谱。主要研究在疲劳载荷下，索锚结构中的三类典型焊接细节(十字型双向承载焊缝连接细节、T 型承拉剪焊缝连接细节以及压弯焊缝疲劳细节)的疲劳性能和拉吊索在腐蚀、氢脆等受损情况下的疲劳性能，深入研究应力集中对结构疲劳性能的影响。基于断裂力学理论，进行数值模拟和试验研究，研究分析索锚传力结构中三类细节的应力集中系数、应力强度因子放大系数和断裂韧性；研究钢丝由于腐蚀、氢脆等因素产生的应力集中现象，分析其对拉吊索的疲劳性能的影响。在考虑索系统中各部分不同设计寿命的前提下，针对索系统结构疲劳评估中各参数的随机性和不确定性，对大跨度索桥中的索系统进行可靠度分析和安全性评估，为相应的疲劳细节设计规范的制修订提供技术支撑。

对于大跨度索桥中索系统的疲劳脆断等问题，进行了相应的数值模拟和模型试验研究。调研了大跨度索桥的典型疲劳车特点，由数值模拟给出了跨海索桥的载荷谱，研究索系统中各部分结构的局部应力谱。主要研究了在疲劳载荷下，索锚结构中的三类典型焊接细节(十字型双向承载焊缝连接细节、T 型承拉剪焊缝连接细节以及压弯焊缝疲劳细节)的疲劳性能和拉吊索在腐蚀氢脆等损伤情况下的疲劳性能，研究了应力集中对结构疲劳性能的影响规律。用断裂力学理论，进行了数值模拟和模型试验，分析了索锚传力结构中三类细节的应力集中系数、应力强度因子放大系数和断裂韧性；分析了钢丝由于腐蚀氢脆等因素产生的应力集中现象，分析其对拉吊索的疲劳性能的影响规律。在考虑索结构中各部分不同设计寿命的前提下，针对索系统的结构疲劳评估中各参数的随机性和不确定性，对大跨度索桥中的索系统进行了可靠度分析和安全性评估，为相应的疲劳细节设计规范的制修订提供了技术支撑。