铁路钢桥节点既有腐蚀疲劳裂纹扩展寿命
Corrosion fatigue crack propagation life of joints of railway steel bridge

为评估服役中铁路钢桥由于环境腐蚀作用产生初始裂纹后的剩余疲劳寿命，对列车行走荷载作用下铁路钢桥节点横梁处在环境腐蚀形成初始裂纹后的疲劳裂纹扩展寿命进行研究。以铜九（铜陵―九江）线鄱阳湖铁路钢桥为背景，基于子模型法的多尺度建模方法，运用通用有限元软件建立铁路钢桥整体壳体模型和节点横梁处含初始裂纹的精细网格划分的实体模型，获得了在列车行走荷载作用下铁路钢桥节点横梁处的精确动应力响应；基于断裂力学的四参数Forman公式对铁路钢桥在4种不同初始裂纹长度下的腐蚀疲劳裂纹扩展寿命进行了评估与对比，并对有无环境腐蚀作用下的疲劳裂纹扩展寿命进行了对比分析。结果表明：基于子模型法的壳？彩堤宥喑叨冉？模方法既可以满足大型复杂结构在数值计算过程中的计算效率，又能够满足评估疲劳寿命计算所需的精确动力响应要求，可以精确评估铁路钢桥腐蚀疲劳裂纹扩展寿命；铁路钢桥既有腐蚀疲劳裂纹扩展寿命主要产生在小裂纹扩展阶段，计算得到0.5 mm初始裂纹扩展到10 mm时需要循环？？484 509？？次，占总扩展寿命的50.2%；铁路钢桥疲劳裂纹扩展寿命受环境腐蚀的影响非常大，其比无腐蚀疲劳裂纹扩展寿命降低79%左右。研究结果可为预测疲劳裂纹发展趋势、评估铁路钢桥剩余寿命和评定结构的安全性与运营能力提供参考。
In order to evaluate the residual fatigue life of the serviced railway steel bridge after the occurrence of initial crack due to the environmental corrosion, the corrosion fatigue crack propagation life of crossbeam region on joints of steel railway bridge after the existence of corrosion fatigue crack in the environmental corrosion was studied under the train running load in this paper. Taking the Poyang Lake Railway Steel Bridge on Tongjiu (Tongling to Jiujiang) Line as a research background, the integral shell element model of steel railway bridge and the finely meshed solid model of joints with initial crack were established by using general finite element software based on the multi？？scale modeling method of the sub？？model method. The precise dynamic stress response of the joints of steel railway bridge was obtained under the train running load. The corrosion fatigue crack propagation life of steel railway bridge with four different initial crack lengths were evaluated and compared based on the four parameters Forman formula, and the crack propagation life with or without environmental corrosion of railway steel bridge was analyzed and compared. The results show that the shell？？solid multi？？scale modeling method based on the sub？？model method can not only meet the computational efficiency of the large？？scale complex structure in the numerical calculation process, but also meet the requirements of precise dynamic response required for the calculation of fatigue life, and it can accurately evaluate corrosion fatigue crack propagation life of railway steel bridge. The corrosion fatigue crack propagation life of railway steel bridge is mainly produced in the small crack propagation stage, a 0.5 mm initial crack enlarging to 10 mm needs cycle 484 509 times, it account for 50.2% of the total propagation life. The fatigue crack propagation life of railway steel bridge is largely affected by environmental corrosion, and it is reduced by 79% compared with the fatigue crack propagation life without corrosion. The