大跨度桥梁钢桥面板跨尺度疲劳损伤评估方法

大跨度斜拉桥正交异性钢桥面板的顶板与纵肋焊接构造细节在车辆荷载作用下易产生疲劳损伤进而导致服役性能降低、影响行车安全。为评估大跨度桥梁钢桥面板的疲劳性能，提出基于细观损伤力学的大跨度钢桥疲劳损伤跨尺度评估方法；推导了基于细观损伤力学的钢桥面板疲劳损伤演化模型，在此基础上，结合实测交通数据，实现了基于Monte-Carlo法的随机车流模拟；最后，将提出的方法应用于一座大跨度三塔斜拉桥。研究结果表明，大跨度斜拉桥钢桥面板体系焊缝周围区域的累积疲劳损伤程度明显高于桥面板体系的其他部位；顶板与纵肋焊接构造细节的疲劳损伤累积呈现明显的非线性，预测的疲劳寿命远小于Miner线性疲劳损伤累积准则的结果。

Multiscale fatigue damage assessment method for orthotropic steel deck of long-span bridges

Orthotropic steel deck (OSD) in a long-span cable-stayed bridge is vulnerable to fatigue damage at the rib-to-deck (RD) joints due to traffic vehicle load. An algorithm for fatigue damage evaluation simulation of long-span bridge based on mesoscale damage model is presented in this paper. Firstly, the fatigue damage evolution model of steel deck based on microscopic damage mechanics is derived. Combined with the measured traffic data, the random traffic flow simulation is realized based on Monte-Carlo method. Finally, it is applied to estimate the damage accumulation of a multi-span cable-stayed bridge. The results indicate that the fatigue damage accumulation at the rib-to-deck (RD) joints is greater than other areas of the OSD. The cumulative rate of fatigue damage at the rib-to-deck (RD) joints shows a strong nonlinear trend. The results are also compared with those estimated by the linear Miner,s model. The predicted fatigue life is far less than that by the linear Miner,s model.