基于概率密度演化理论的锈蚀钢梁时变可靠度分析

为了得到锈蚀钢梁时变可靠度,对9组试件分别开展了加速腐蚀试验和单调拉伸试验.测得了锈蚀深度三维坐标数据和锈蚀钢材名义屈服强度,统计分析了锈蚀深度和名义屈服强度概率模型.建立了锈蚀钢梁功能函数,结合概率密度演化理论得到了锈蚀钢梁时变失效概率和可靠指标,并与蒙特卡洛方法(MCS)计算结果进行了对比.结果表明:钢板表面锈蚀深度和名义屈服强度服从正态分布;随着腐蚀时间增加,锈蚀深度均值和标准差不断增大;随着失重率增加,名义屈服强度均值不断减小而标准差不断增大;概率密度演化方法与MCS计算结果较接近,说明本文提出的方法的有效性;锈蚀深度和强度的随机性对锈蚀钢梁可靠度影响较大.

Time-dependent Reliability Analysis of Corroded Steel Beam Based on Probability Density Evolution Theory

To obtain the time-dependent reliability of corroded steel beam, accelerated corrosion test and monotonic tensile test were carried out on 9 groups of specimens. 3D data of corrosion depth and the nominal yield strength of corroded steel were measured. Probability model of corrosion depth and nominal yield strength of corroded steels was statistically analyzed, and performance function of the corroded steel beam was established. Then, based on probability density evolution theory, the time-dependent failure probability and reliability index of corroded steel beams were obtained, which were compared with those calculated by Monte Carlo simulation (MCS) method. The results of the study show that the corrosion depth on surface and nominal yield strength of corroded steels obey the normal distribution. With the increase of corrosion time, the mean and standard deviations of the corrosion depth increase. With the increase of weight loss ratio, the mean of nominal yield strength decreases whereas the standard deviation of nominal yield strength increases. Probability density evolution method is closer to calculation results of the MCS, which shows that the method proposed in this paper is effective. The randomness of corrosion depth and strength has great influence on the reliability of corroded steel beams.