酸雨环境下斜拉索应力腐蚀与腐蚀疲劳试验研究
发布时间：2019-07-02 10:32
【摘要】：斜拉桥以优美的结构形式,轻盈的体态和独特的受力特点而备受桥梁设计者们青睐,我国也成为斜拉桥建造大国,但斜拉索的应力腐蚀与疲劳腐蚀一直是斜拉桥研究的前沿课题,本文以斜拉桥拉索系统在酸雨环境下的加速试验为支撑,通过对斜拉索施加交变荷载、静态荷载和无荷载作为对比条件,研究斜拉索的腐蚀过程及疲劳腐蚀与应力腐蚀机理。在试验结果的处理上,以失重法来衡量不同的荷载条件下斜拉索的腐蚀速率,同时以《中国大气腐蚀调查报告》中的大气腐蚀监控点的大气暴晒腐蚀速率为基本对比条件,得出在加速试验中个试件的腐蚀情况与腐蚀速率,同时得出在酸雨环境下斜拉索的不同受力形式的腐蚀速率与大气腐蚀速率的等同性;通过试验研究得出:三种试件在5天试件内的腐蚀速率基本一致,在15天的试验交变荷载条件下试件的腐蚀速率明显大于静态荷载条件下试件的腐蚀速率与无荷载条件下试件的腐蚀速率,而静态荷载条件下试件的腐蚀速率又大于无荷载条件下试件的腐蚀速率;通过与西南地区大气暴晒实验点的腐蚀数据做对比得出:交变荷载下腐蚀速率30天后的每天的腐蚀速率为实际大气暴晒下的2年;静态荷载下30天后的每天的腐蚀速率为实际大气暴晒下的1.46年。同时通过扫描电子显微镜观测到应力腐蚀与疲劳腐蚀的不同及微裂纹的扩展情况,及裂纹形核的形成条件与纳米级裂纹的扩展,疲劳腐蚀中主裂纹与次裂纹的扩展条件,及在应力腐蚀中小裂纹与大裂纹的发展趋势。对腐蚀的结果进行MATLAB中元胞自动机的编码进行模拟在交变荷载与静态荷载条件下试件的腐蚀腐蚀动力学,从而得出均匀腐蚀与点蚀的关系;以ANSYS12.0有限元软件为依托,对不同腐蚀情况下的斜拉索进行有限元分析,得出应力与蚀坑深度的关系,应力与蚀坑间距的关系。在得到以上的各个结论后,提出斜拉桥拉索寿命预测公式,通过重庆地区的斜拉桥进行预测公式的计算,在通过以上的各个结论推出拉索失效的判据,同时以南太湖大桥为例进行了斜拉索寿命分析。
[Abstract]:The cable-stayed bridge has been favored by the bridge designers in the form of graceful structure, light posture and special stress. The cable-stayed bridge also becomes a large-power cable-stayed bridge, but the stress corrosion and fatigue corrosion of the stay cable have been the leading problem in the research of the cable-stayed bridge. In this paper, the accelerated test of cable-stayed cable system in acid rain environment is supported, and the corrosion process of the stay cable and the mechanism of fatigue corrosion and stress corrosion are studied by applying the alternating load, static load and no-load to the stay cable as the comparison condition. On the basis of the test results, the corrosion rate of the stay cable under different loading conditions is measured by the weight loss method, and the atmospheric corrosion rate of the atmospheric corrosion monitoring point in the Report of the Atmospheric Corrosion in China is the basic contrast condition. The corrosion rate and the corrosion rate of the test piece in the accelerated test are obtained, and the equivalent of the corrosion rate and the atmospheric corrosion rate in different stress forms of the stay cable under the acid rain environment is obtained. The test results show that the corrosion rate of the three test pieces in the 5-day test piece is basically the same, The corrosion rate of the test piece is obviously higher than the corrosion rate of the test piece under the static load condition and the corrosion rate of the test piece under the static load condition is greater than the corrosion rate of the test piece under the condition of no load; It is concluded that the rate of corrosion per day after 30 days of the corrosion rate under the alternating load is 2 years of the actual exposure to the atmosphere, and the rate of corrosion per day after 30 days of static loading is 1.46 years of the actual exposure to the atmosphere. At the same time, by scanning electron microscope, the difference of stress corrosion and fatigue corrosion and the expansion of micro-cracks, the formation condition of crack nucleation and the expansion of the nano-scale crack, the extension condition of the main crack and the secondary crack in the fatigue corrosion, And the development trend of small cracks and large cracks in stress corrosion. The corrosion and corrosion dynamics of the specimen under the condition of alternating load and static load are simulated by the coding of the cellular automaton in MATLAB, and the relationship between the uniform corrosion and the pitting corrosion is obtained. Based on the ANSYS12.0finite element software, The relationship between the stress and the depth of the pit and the relation between the stress and the pit pitch are obtained by the finite element analysis of the stay cable under different corrosion conditions. After the conclusion of the above conclusions, the formula of the cable life prediction of the cable-stayed bridge is put forward, and the calculation of the prediction formula is carried out through the cable-stayed bridge in the Chongqing area, and the criterion of the cable failure is introduced through the above conclusions, and the life analysis of the stay cable is carried out in the south of the Taihu Bridge as an example.
【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】：U441.4;U446
本文编号：2508863
[Abstract]:The cable-stayed bridge has been favored by the bridge designers in the form of graceful structure, light posture and special stress. The cable-stayed bridge also becomes a large-power cable-stayed bridge, but the stress corrosion and fatigue corrosion of the stay cable have been the leading problem in the research of the cable-stayed bridge. In this paper, the accelerated test of cable-stayed cable system in acid rain environment is supported, and the corrosion process of the stay cable and the mechanism of fatigue corrosion and stress corrosion are studied by applying the alternating load, static load and no-load to the stay cable as the comparison condition. On the basis of the test results, the corrosion rate of the stay cable under different loading conditions is measured by the weight loss method, and the atmospheric corrosion rate of the atmospheric corrosion monitoring point in the Report of the Atmospheric Corrosion in China is the basic contrast condition. The corrosion rate and the corrosion rate of the test piece in the accelerated test are obtained, and the equivalent of the corrosion rate and the atmospheric corrosion rate in different stress forms of the stay cable under the acid rain environment is obtained. The test results show that the corrosion rate of the three test pieces in the 5-day test piece is basically the same, The corrosion rate of the test piece is obviously higher than the corrosion rate of the test piece under the static load condition and the corrosion rate of the test piece under the static load condition is greater than the corrosion rate of the test piece under the condition of no load; It is concluded that the rate of corrosion per day after 30 days of the corrosion rate under the alternating load is 2 years of the actual exposure to the atmosphere, and the rate of corrosion per day after 30 days of static loading is 1.46 years of the actual exposure to the atmosphere. At the same time, by scanning electron microscope, the difference of stress corrosion and fatigue corrosion and the expansion of micro-cracks, the formation condition of crack nucleation and the expansion of the nano-scale crack, the extension condition of the main crack and the secondary crack in the fatigue corrosion, And the development trend of small cracks and large cracks in stress corrosion. The corrosion and corrosion dynamics of the specimen under the condition of alternating load and static load are simulated by the coding of the cellular automaton in MATLAB, and the relationship between the uniform corrosion and the pitting corrosion is obtained. Based on the ANSYS12.0finite element software, The relationship between the stress and the depth of the pit and the relation between the stress and the pit pitch are obtained by the finite element analysis of the stay cable under different corrosion conditions. After the conclusion of the above conclusions, the formula of the cable life prediction of the cable-stayed bridge is put forward, and the calculation of the prediction formula is carried out through the cable-stayed bridge in the Chongqing area, and the criterion of the cable failure is introduced through the above conclusions, and the life analysis of the stay cable is carried out in the south of the Taihu Bridge as an example.
【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】：U441.4;U446
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1 李涛;交变应力与环境耦合作用下拉索腐蚀疲劳损伤机理研究[D];重庆交通大学;2014年
本文编号：2508863
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