中文摘要：

联合线弹性断裂力学和长期监测数据提出了大跨桥梁焊接细节疲劳可靠度评估方法,并以润扬大桥钢箱梁的焊接细节为对象开展了应用研究。首先,采用长期监测数据建立了疲劳荷载效应的概率模型;其次,推导了焊接细节疲劳断裂抗力的表达式,分析了初始裂纹深度和极限裂纹深度对断裂抗力的影响规律,采用随机数值模拟的方法得到了断裂抗力的概率模型;最后研究了交通荷载增长条件下焊接细节疲劳可靠度的时变规律。研究表明：断裂抗力服从对数正态分布,且对初始裂纹深度极为敏感;当考虑交通荷载增长,桥梁的服役期还未满设计基准期时,焊接细节的可靠度就将低于目标可靠度水平。

英文摘要：

A fatigue reliability assessment method is developed,based on the combination of linear elastic fracture mechanics and long-term monitoring data,and the application research is presented with the object of welded details for Runyang Bridges.The probabilistic models of the fatigue loading effects are obtained by the basis of the long-term monitoring data first.Then the expression of the fracture resistance is derived.And the effect law of the initial and critical crack depth on the fracture resistance is analyzed.On this basis,the random numerical simulation is employed to obtain the probabilistic model of fracture resistance.At last the time-variant law of the fatigue reliability is studied in detail with the consideration of traffic growth.The results show that fracture resistance follows a lognormal distribution and is very sensitive to initial crack depth.By the consideration of the traffic growth,the fatigue reliability of welded details will be less than the level of the target reliability when the service time does not reach the design reference period.