桥梁索体钢丝腐蚀特征和力学性能试验研究

发布时间：2018-04-08 20:52

本文选题：钢丝　切入点：腐蚀速率　出处：《东南大学》2015年硕士论文

【摘要】：索体是缆索承重体系桥梁中重要的传力和承载构件,在桥梁设计基准期内,索体钢丝易受到环境和力学等因素的影响发生腐蚀损伤导致其力学性能退化。本文通过钢丝的电化学腐蚀试验、表面腐蚀特征分析、力学拉伸试验和疲劳试验研究了钢丝的腐蚀特征和力学性能,主要研究过程和研究成果如下：1)首先,探讨了钢丝腐蚀机理,然后利用电化学腐蚀试验研究了温度、应力、氯盐浓度、pH值四种单因素对钢丝基体腐蚀速率的影响,建立了腐蚀速率与各单因素间的函数关系式；最后基于响应面法试验设计,研究了温度、应力、氯盐浓度、pH值交互作用对钢丝基体腐蚀速率的影响,建立钢丝基体腐蚀速率与多因素间的函数关系式。研究表明,各单因素都会影响钢丝基体的腐蚀速率,且各因素间存在显著的交互作用。2)其次,对旧索腐蚀钢丝的蚀坑尺寸进行了量化检测,然后利用数理统计方法研究了蚀坑尺寸的分布特征,并分析了蚀坑尺寸与均匀腐蚀之间的关系。研究表明,平均腐蚀深度、蚀坑深度服从广义极值分布,蚀坑长度、宽度服从对数正态分布。3)第三,通过对新钢丝和旧钢丝进行了力学拉伸试验,得到了新、旧钢丝力学性能参数,研究了钢丝力学性能参数分布规律,并分析了钢丝拉伸断口特征。研究表明,钢丝延伸率、屈服强度、极限强度都随着腐蚀程度的增加而下降,且钢丝极限强度下降速率大于屈服强度；对钢丝力学性能的退化评价采用最大蚀坑深度作为参数比采用平均腐蚀深度更加合理和准确。4)第四,通过对新钢丝、表面无腐蚀损伤钢丝、预制蚀坑钢丝进行疲劳试验,拟合得到了各钢丝试样的S-N曲线,研究了钢丝疲劳寿命变化规律,并分析了钢丝疲劳断口特征。研究结果表明：在低应力幅值下,表面无腐蚀损伤钢丝疲劳寿命下降较小,但有腐蚀损伤钢丝疲劳寿命随着腐蚀程度的增加下降幅度较大；在低应力幅值下,预制蚀坑钢丝疲劳寿命随腐蚀时间的增加、蚀坑深度的增加而下降；在高应力幅值下表面无腐蚀损伤钢丝、预制蚀坑钢丝疲劳寿命与新钢丝相比都出现了明显的下降,且疲劳寿命离散性增加。
[Abstract]:Cable body is one of the most important load-transfer and load-carrying components in cable-bearing system. During the reference period of bridge design, steel wire of cable body is susceptible to corrosion damage caused by environmental and mechanical factors, resulting in degradation of mechanical properties.In this paper, the corrosion characteristics and mechanical properties of steel wire are studied by electrochemical corrosion test, surface corrosion characteristic analysis, mechanical tensile test and fatigue test.The corrosion mechanism of steel wire was discussed, and the influence of four factors, temperature, stress, chloride concentration and pH value, on the corrosion rate of steel wire substrate was studied by electrochemical corrosion test, and the functional relationship between corrosion rate and each single factor was established.Finally, based on the experimental design of response surface method, the effects of temperature, stress, chloride concentration and pH value on the corrosion rate of steel wire matrix are studied, and the functional relationship between the corrosion rate of steel wire matrix and multiple factors is established.The results show that each single factor will affect the corrosion rate of steel wire matrix, and there is a significant interaction between each factor. Secondly, the corrosion pit size of corroded steel wire with old cables is measured quantitatively.Then the distribution of the size of the pit is studied by means of mathematical statistics, and the relationship between the size of the pit and the uniform corrosion is analyzed.The results show that the average corrosion depth, the depth coat of the pit is distributed from the generalized extreme value, the length and width of the pit are distributed from the logarithmic normal distribution. Third, the new steel wire and old steel wire are obtained through mechanical tensile tests on the new steel wire and the old steel wire.The distribution of mechanical property parameters of old steel wire was studied, and the tensile fracture characteristics of steel wire were analyzed.The results show that the elongation, yield strength and ultimate strength of steel wire decrease with the increase of corrosion degree, and the decreasing rate of ultimate strength of steel wire is higher than that of yield strength.The degradation evaluation of steel wire mechanical properties using the maximum pit depth as the parameter is more reasonable and accurate than the average corrosion depth. Fourth, the fatigue test is carried out on the new steel wire, the steel wire without corrosion damage on the surface, and the prefabricated corrosion pit steel wire.The S-N curves of each steel wire sample were obtained, the fatigue life of steel wire was studied, and the fatigue fracture characteristics of steel wire were analyzed.The results show that the fatigue life of non-corrosion-free surface steel wire decreases slightly under low stress amplitude, but the fatigue life of corroded steel wire decreases greatly with the increase of corrosion degree, and at low stress amplitude, the fatigue life of corrosion-free steel wire decreases with the increase of corrosion degree.The fatigue life of prefabricated corrosion-pit steel wire decreases with the increase of corrosion time and decreases with the increase of corrosion depth, and the fatigue life of prefabricated pit steel wire decreases obviously compared with that of new steel wire under high stress amplitude.And the fatigue life dispersion increases.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.38

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