损伤拉索剩余寿命预测模型与破损安全评价方法研究

发布时间：2018-01-08 19:06

本文关键词：损伤拉索剩余寿命预测模型与破损安全评价方法研究　出处：《重庆交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：斜拉桥由于其具有的结构自重轻,跨越能力得到提高,施工更加便捷；桥墩少,受船只撞击的几率小,通航宽度大,通航能力强；结构的横向刚度大,抗风能力强；造型美观等优点,在20世纪得到飞速的发展。拉索,作为斜拉桥的最主要承重传力构件,由于其结构尺寸相对较小,使其成为斜拉桥结构体系中最容易受到损伤的构件之一,且对病害的敏感程度较高。据统计,现阶段出现的斜拉桥病害中,出现在拉索的各种病害占了绝大部分。这些病害使拉索的力学性能下降,锈蚀加快,耐久性降低。因此对损伤拉索的研究对斜拉桥发展与安全运营具有十分重大意义。在本文中,研究了拉索的腐蚀机理,外界环境对拉索的腐蚀速率产生影响的机理,环境中哪些因素对拉索腐蚀速率的影响大。根据电化学原理和正交实验原理设计电化学的试验方案,研究了在外界温度、氯盐的含量、PH值以及他们之间的两两的交互作用对高强度钢丝腐蚀的影响,分析了高强度钢丝的腐蚀速率和外界环境腐蚀因子之间的函数关系。为了研究拉索的腐蚀,建立了一个腐蚀因子的扩散模型,当拉索护套破损后,分析了外界环境中的腐蚀因子沿着护套破损处往拉索内部扩散的机理。扩散模型根据菲克定律和实际情况建立数学物理方程,拟定边界条件和初始条件,解出此数学物理方程,得出时间和位置与腐蚀因子浓度之间的函数关系。在得出拉索内部高强度钢丝周围的腐蚀因子浓度后,再根据不同腐蚀因子浓度与钢丝的腐蚀速率之间的函数关系,最后得到了高强度钢丝及拉索的腐蚀量。在经过严密的理论推导、数学计算后,最终得到了计算拉索腐蚀量的方法,推导出了拉索力学性能退化程度,对拉索的承载能力重新进行了评估。在此基础上提出了拉索安全评定的三大判据,即承载能力判定依据,腐蚀量判定依据和断丝率判定依据。依据规范把拉索分成了五个等级,并以此来评估拉索的安全性。根据拉索的腐蚀全过程,和拉索的安全判定依据,提出了预测拉索的寿命具体流程和方法,从而为确定拉索的更换时间提供了理论依据。
[Abstract]:The cable-stayed bridge is more convenient to be constructed because of its light structure weight and improved span capacity. The bridge pier is few, the probability of being hit by the ship is small, the navigation width is large, the navigation ability is strong; The transverse stiffness of the structure is large and the wind resistance is strong; In 20th century, the cable, as the main load-carrying component of cable-stayed bridge, was developed rapidly in 20th century because of its relatively small structure size. It is one of the most vulnerable components in the cable-stayed bridge structure system, and the sensitivity to the disease is high. According to statistics, in the current stage of cable-stayed bridge diseases. Most of the diseases appear in the cable. These diseases decrease the mechanical properties of the cable and accelerate the corrosion. Therefore, the study of damaged cables is of great significance to the development and safe operation of cable-stayed bridges. In this paper, the corrosion mechanism of cables is studied. The influence of external environment on the corrosion rate of cables, and which factors in the environment have a great effect on the corrosion rate of cables. According to the principle of electrochemistry and orthogonal experiment, the experimental scheme of electrochemistry is designed. The effects of external temperature, pH value of chloride salt and the interaction between them on the corrosion of high strength steel wire were studied. The functional relationship between corrosion rate of high strength steel wire and external environmental corrosion factor was analyzed. In order to study the corrosion of cable, a diffusion model of corrosion factor was established, when the sheath of cable was damaged. The diffusion mechanism of corrosion factors in the external environment along the damaged sheath to the cable is analyzed. The diffusion model establishes the mathematical and physical equations according to Fick's law and the actual conditions, and draws up the boundary conditions and initial conditions. The mathematical and physical equation is solved, and the functional relationship between the time and position and the concentration of corrosion factor is obtained, and the concentration of corrosion factor around the high strength steel wire inside the cable is obtained. Then according to the function relationship between the different concentration of corrosion factor and the corrosion rate of steel wire, the corrosion quantity of high strength steel wire and cable is obtained. Finally, the method of calculating cable corrosion is obtained, the degree of degradation of cable mechanical properties is deduced, and the load-carrying capacity of cable is re-evaluated. On this basis, three criteria for cable safety evaluation are proposed. According to the criterion, the cable is divided into five grades, and the safety of the cable is evaluated. According to the corrosion process of the cable, the whole process of cable corrosion is evaluated. The concrete flow and method of predicting the life of cables are put forward, which provides a theoretical basis for determining the replacement time of cables.
【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】：U446

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