复杂环境下钢筋混凝土桥梁损伤概率模型及可靠度分析

Damage probability model and reliability analysis of reinforced concrete bridge in complicated environment

综合考虑氯离子的结合作用、水灰比、温度和湿度因素对钢筋锈蚀的初始时间的影响,对Fick第二定律进行改进,建立了初锈时间模型.并通过Monte Carlo数值模拟技术,对钢筋混凝土桥梁的保护层厚度、表面氯离子浓度、扩散系数和临界氯离子浓度进行随机抽样,进行了正常使用极限状态下的可靠度计算.研究结果表明,钢筋对锈蚀的敏感程度依次为:保护层厚度、临界氯离子浓度、扩散系数、表面氯离子浓度;随着锈蚀率的增加,桥梁在使用年限达到65年之后,失效概率达到1,同时使用年限下降27%.

The initial corrosion time model was developed based on the modification of the second law of Fink, in which the effect of bonding function between chloride ions, tempera- ture and humidity on the initial corrosion of steel were taken into account. Then the Monto Carlo numerical simulation technology was used to randomly select a series of parameters of reinforced concrete bridge, which contained the thickness of concrete cover, superficial chloride concentration, diffusion coefficient and critical chloride concentration ,the reliabili- ty under serviceability limit states was calculated. The study indicates that in order of most influencing factor on steel corrosion ,it goes the thickness of concrete cover, critical chloride concentration, diffusion coefficient and superficial chloride concentration. As the corrosion ratio increased, the probability of failure achieved land service life period decreased 27% af- ter the service life period reached 65 years.