随机腐蚀作用下在役钢桥疲劳抗力概率密度演化方法  

Probability Density Evolution Method of Fatigue Resistance for Existing Steel Bridge Under Stochastic Corrosion Effect

作　　者：贾东林[1] 张清华[1] 陈李桥 崔闯 江湧[2] JIA Dong-lin;ZHANG Qing-hua;CHEN Li-qiao;CUI Chuang;JIANG Yong(Department of Bridge Engineering,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;China Railway Major Bridge Engineering Group Co.Ltd.,Wuhan 430050,Hubei,China)

机构地区：[1]西南交通大学桥梁工程系,四川成都610031 [2]中铁大桥局集团有限公司,湖北武汉430050

出　　处：《中国公路学报》2023年第5期163-174,共12页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51978579,51878561,51778533,52108176);桥梁结构健康与安全国家重点实验室开放课题(BHSKL19-06-KF);四川省交通运输科技项目(2020-B-02)。

摘　　要：腐蚀和疲劳开裂严重危害在役钢桥服役安全,随机腐蚀作用导致疲劳抗力发生概率性劣化,结构面临的不确定性风险进一步增加。为准确评估随机腐蚀作用下在役钢桥的疲劳抗力及其演化特性,基于广义概率密度演化理论,建立了腐蚀-疲劳抗力概率密度演化方程。根据齐次马尔可夫过程和实桥腐蚀深度统计数据,确定了腐蚀深度概率密度函数的理论预测模型。基于腐蚀试件疲劳试验结果,确定了腐蚀深度和疲劳抗力的相关关系。在此基础上,针对一座典型在役钢桥疲劳抗力开展了概率密度演化分析,确定了随机腐蚀作用下在役钢桥疲劳抗力的概率密度函数及其演化特征,并采用蒙特卡洛抽样方法验证了结果的正确性。研究结果表明:疲劳抗力的概率密度函数分布特征与其自身方程密切相关,相同腐蚀作用下不同循环次数对应的疲劳强度概率密度函数存在显著差异;随着服役时间的增加,疲劳抗力的概率密度函数进一步发生演化,由腐蚀-疲劳抗力方程所决定,疲劳抗力概率密度等值线逐渐密集,概率密度峰值不断提高,随机腐蚀作用对于疲劳抗力的劣化效应越发集中;随机腐蚀作用下,在役钢桥的疲劳抗力呈现概率性劣化,服役时间为100年时,在95%保证率下,200万次对应疲劳强度仅为47 MPa,相比服役20年时疲劳强度降幅达到60%,随机腐蚀作用对于疲劳抗力的劣化效应不可忽略。Corrosion and fatigue cracking seriously endanger the service safety of existing steel bridges.Fatigue resistance is probabilistic deteriorated by the stochastic corrosion effect,and the uncertainty risk of structure is further increased.In order to accurately evaluate the fatigue resistance of existing steel bridges and its evolution characteristics under stochastic corrosion,the probability density evolution equation of corrosion-fatigue resistance was established based on the generalized probability density evolution theory.The theoretical prediction model of probability density function of corrosion depth was determined by the homogeneous Markov process and statistical data of corrosion depth of in-site bridge.The relationship of corrosion depth and fatigue resistance was determined according to the fatigue test results of corrosion specimens.On the basis of that,the probability density evolution of fatigue resistance of a typical existing steel bridge was analyzed.The probability density function of fatigue resistance of existing steel bridge and its evolution characteristics were determined under stochastic corrosion.The correctness of the results was verified by the Monte Carlo sampling method.The results show that the distribution of probability density function of fatigue resistance is closely related to its own relationship,and significant differences were found in the probability density function of fatigue strength corresponding to different cycles under the same corrosion effect.With the increase of service time,the probability density function of fatigue resistance further evolved.Determined by the equation of corrosion-fatigue resistance,the probability density contours are gradually dense and the probability density peaks is increasing.The degradation effect of stochastic corrosion on fatigue resistance is more concentrated.The fatigue resistance of the existing steel bridge under stochastic corrosion was probabilistic deteriorated.When the service time is 100 years,the corresponding fatigue stren

关 键 词：桥梁工程 疲劳抗力 概率密度演化方法 随机腐蚀作用 在役钢桥 

分 类 号：U441.4[建筑科学—桥梁与隧道工程]