锈蚀和疲劳耦合作用下梁桥时变承载力评估

TIME-VARYING BEARING CAPACITY EVALUATION OF BRIDGE UNDER COUPLING ACTION OF CORROSION AND FATIGUE

钢筋混凝土桥梁在环境和荷载双重作用下将出现锈蚀、粘结退化和疲劳损伤,现有承载力计算方法不能同时考虑三者的综合影响。根据已有成果系统阐述锈蚀、粘结退化和疲劳损伤对承载力的影响,分析锈蚀和疲劳耦合作用下的钢筋面积退化情况。根据锈蚀钢筋与混凝土界面间的变形协调关系推导多因素影响下截面协同工作系数的表达式,提出同时考虑锈蚀、粘结退化和疲劳损伤的承载力计算方法。以钢筋混凝土简支梁为例,对其承载力退化过程进行理论分析和数值模拟。结果表明:所提出的承载力评估方法可以合理准确地反映桥梁在疲劳和锈蚀耦合作用下的承载力退化过程,可为计算锈蚀和疲劳耦合作用下桥梁承载力评估提供参考。

For the reinforced concrete bridges,the degeneration phenomenon such as corrosion,bond degradation and fatigue damage will occur under the double action of environmental effect and loading.The comprehensive action of the three factors cannot be entirely considered according to the current bearing capacity calculation methods.The influence of corrosion,bond degradation and fatigue damage on the bearing capacity of RC bridge was intensively elaborated based on the existing achievements,and the reduction of reinforcement area under the coupling action of corrosion and fatigue was analyzed.The analytic expression of cross section cooperative work coefficient was deduced according to the deformation coordination relationship between corroded steel bar and concrete interface,and the bearing capacity calculation method considering corrosion,bond degradation and fatigue damage was proposed.Taking one reinforced concrete simply supported beam as an example,the degradation process of bearing capacity was analyzed by the finite element method and the theoretical method proposed in this study,respectively.The results show that the evaluation method of bearing capacity considering coupling effects can reasonably represent the degradation process of bearing capacity under the action of fatigue and corrosion.The new method can be used as an effective reference for evaluating the bearing capacity of RC bridges under the coupling action due to corrosion and fatigue.