基于长期监测数据的桥面板焊接细节疲劳寿命评估

Fatigue life assessment of welds in bridge decks using long term monitored data

基于润扬大桥结构健康监测系统,对钢桥面顶板-纵肋焊接细节附近的疲劳应变进行了长达两年的监测。采用Butterworth滤波以去除应变过程中的电磁干扰,然后通过简化雨流计数提取应变循环,并根据Palmgren-Miner准则和双线性概率S-N曲线对焊接细节进行了疲劳寿命评估。通过实测的环境温度、交通流量以及车辆荷载的疲劳等效,分析了车辆荷载和环境温度的变化对于桥面焊接细节疲劳损伤的影响。研究发现,环境温度对桥面焊接细节疲劳损伤存在着近似线性的影响。比较了润扬悬索桥与斜拉桥对应位置焊接细节的疲劳损伤分析结果,发现环境温度对于疲劳损伤的影响可能普遍存在于大跨缆索支承钢桥中。根据预测的车辆荷载增长模型以及拟合得到的温度、车辆荷载与疲劳损伤的关系,对焊接细节的疲劳寿命评估结果进行了修正。

Based on the structural health monitoring system of the Runyang Bridge, two years of strain monitoring on the welded rib-to-deck connections has been made. The electromagnetic interference is removed from the strain data by using the Butterworth filtering, and the strain cycles are extracted through the simplified rainflow counting algorithm. Thereafter fatigue reliability assessment is conducted by using the Palmgren-Miner rule and bilinear probabilistic S-N curves. According to the recorded ambient temperature, traffic volume and the fatigue equivalence of axle loadings, the influences of vehicle loadings and ambient temperature are analyzed. It can be found that the ambient temperature has an approximately linear effect on the fatigue damage of the welds in bridge decks. By comparison of the fatigue damage in weldeds between the Runyang Suspension Bridge （BSB） and the Runyang Cable-stayed Bridge （RCB）, it is observed that the influence of temperature on the fatigue damage may widely exist in long-span cable-supported steel bridges. Based on the predicted traffic model and the fitted relationship of temperature, traffic loading and fatigue damage, results of the fatigue assessment are modified.