桥梁拉吊索用不锈钢钢丝腐蚀性能研究及桥梁拉索时变可靠度评估

发布时间：2018-06-19 23:10

本文选题：桥梁工程 + 腐蚀　；参考：《大连理工大学》2015年硕士论文

【摘要】：拉吊索腐蚀是桥梁设计和施工必须考虑的重要方面之一,特别是跨海大桥。目前,拉吊索所用材料大多数为高强碳素钢丝或钢绞线,材料在桥梁实际运营中长期处于高应力状态,对外界环境侵蚀比较敏感。随着桥梁使用年限的增长,拉吊索逐步暴露出防腐层老化、锈蚀、断丝等问题,需要花费大量人力财力进行更换,否则可能会导致索断裂、引起桥梁垮塌等事故。为提高桥梁拉吊索的使用寿命,降低维护和更换成本,需要开发新型拉吊索材料。本文结合交通运输部科技项目“全寿命不锈钢钢丝索开发研究”和国家基础性项目(973项目)“特大跨桥梁安全性设计与评定的基础理论研究”,对不锈钢钢丝的耐腐蚀性能进行了研究,并对用不锈钢钢丝作桥梁拉索时的时变可靠度进行了分析。本文主要内容和结论如下：(1)对拉吊索腐蚀环境及腐蚀类型进行了讨论,分析了拉吊索各种类型腐蚀的机理及影响因素。(2)对零应力的普通镀锌单根钢丝及施加0、20%、30%和40%四个水平应力的单根不锈钢钢丝,分7d、20d和40d进行中性盐雾试验,测量钢丝的质量损失率,分析得到不同钢丝的截面面积损失系数；研究了零应力普通镀锌钢丝和不同应力水平下不锈钢钢丝的荷载-变形曲线,对拉伸后的钢丝进行了扫描电镜分析。研究表明,零应力下,普通镀锌钢丝的重量损失率为不锈钢钢丝的30倍以上,不锈钢钢丝的防腐性能远好于普通镀锌钢丝。不锈钢钢丝的重量损失率随着施加应力的增加而增加,高应力下的不锈钢钢丝更容易腐蚀。短期内腐蚀对钢丝的极限强度影响不大；随着腐蚀的增加,普通镀锌钢丝和不锈钢钢丝的拉伸断口呈现脆性增加的趋势,普通镀锌钢丝的断口形貌由微裂纹向长宽裂纹发展,而不锈钢钢丝由于腐蚀程度较轻,只是出现了微裂纹。(3)利用ANSYS有限元建立了某斜拉桥的结构分析模型,建立了桥梁在自重和随机车辆荷载作用下的斜拉索索力概率模型,分别假定将本文研究的普通镀锌钢丝和不锈钢钢丝作为桥的斜拉索,考虑本文试验研究得到的截面面积损失系数建立斜拉索的功能函数,采用一次二阶矩方法计算得到了普通镀锌钢丝拉索和不锈钢钢丝拉索的时变可靠指标。分析表明,采用普通镀锌钢丝时可靠指标随时间下降的速度较快,而采用不锈钢钢丝时可靠指标随时间下降的速度较慢。
[Abstract]:The cable corrosion is one of the most important aspects in bridge design and construction, especially the bridge across the sea. At present, most of the materials used in the slings are high strength carbon steel wire or steel strands. The materials are in high stress state for a long time in the actual operation of the bridge, and are sensitive to the external environment erosion. With the increase of the service life of the bridge, the problems of antiseptic layer aging, corrosion, broken wire and so on are exposed gradually, which need to be replaced with a large amount of manpower and financial resources. Otherwise, it may lead to the rupture of the cable and the collapse of the bridge. In order to improve the service life of bridge slings and reduce the cost of maintenance and replacement, it is necessary to develop a new type of sling material. In this paper, the basic theory research on safety design and evaluation of extra-large span bridges is combined with "Research on the development of stainless steel wire cables for the whole life" of the Ministry of Communications and Transport Science and Technology Project and the National basic Project "Yu973 Project". The corrosion resistance of stainless steel wire was studied, and the time-varying reliability of stainless steel wire as bridge cable was analyzed. The main contents and conclusions of this paper are as follows: (1) the corrosion environment and corrosion types of the slings are discussed. The corrosion mechanism of various types of slings and its influencing factors were analyzed. The neutral salt spray tests were carried out on ordinary galvanized single steel wire with zero stress and single stainless steel wire with 0 20% and 40% horizontal stress. The neutral salt spray test was carried out for 7 days, 20 days and 40 days, respectively. The mass loss rate of steel wire was measured, and the loss coefficient of cross section area of different steel wire was obtained, and the load-deformation curve of steel wire with zero stress, common galvanized steel wire and stainless steel wire under different stress levels was studied. The tensile steel wire was analyzed by SEM. The results show that the weight loss rate of common galvanized steel wire is more than 30 times of that of stainless steel wire under zero stress, and the corrosion resistance of stainless steel wire is much better than that of common galvanized steel wire. The weight loss rate of stainless steel wire increases with the increase of applied stress, and the stainless steel wire with high stress is more susceptible to corrosion. The short term corrosion has little effect on the ultimate strength of steel wire, with the increase of corrosion, the tensile fracture of common galvanized steel wire and stainless steel wire shows a tendency of increasing brittleness, and the fracture morphology of common galvanized steel wire develops from microcrack to long and wide crack. However, due to the mild corrosion degree of stainless steel wire, there is only a micro-crack. 3) the structural analysis model of a cable-stayed bridge is established by using ANSYS finite element method, and the probabilistic model of cable-stayed cable force of the bridge under the action of deadweight and random vehicle load is established. The conventional galvanized steel wire and stainless steel wire studied in this paper are assumed to be the stay cables of the bridge respectively. The function of the cable is established considering the loss coefficient of the cross-section area obtained by the experiments in this paper. The time-varying reliability indexes of common galvanized wire cables and stainless steel wire cables are calculated by the first-order second-order moment method. The results show that the reliability index decreases faster with time when common galvanized steel wire is used, while the reliability index decreases slowly with time with stainless steel wire.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.38

【参考文献】