润扬悬索桥钢箱梁结构疲劳应力监测及其分析

分析了润扬悬索桥结构健康监测系统记录的钢箱梁结构主要部件在交通和环境载荷下的应变时程曲线的规律,研究得到了润扬悬索桥钢箱梁结构在正常交通载荷、重车过桥和台风经过时的疲劳应力谱的特征;结合该桥实时监测的温度变化,分析得到了钢箱梁结构应变时程和温度时程之间的关联性.研究结果表明:润扬大桥结构健康监测系统中的局部应变监测系统能够有效提供钢箱梁结构疲劳应力监测信息;目前各监测部位的有效应力幅较低,主要由车辆和环境气温变化共同引起,疲劳应力的平均值与环境气温变化有很大相关性;重型卡车通过对桥梁造成的疲劳损伤增量幅值是一般车辆载荷经过时引起的几十甚至上百倍,因此在特大型车辆通过时需要密切关注和监测其引起的过载及其对疲劳累积过程的影响.

Fatigue stress monitoring and analysis for steel box girder of Runyang Suspension Bridge

Based on the strain-history data recorded by structural health monitoring system installed on the bridge the characteristic of strain history of the girder components of Runyang Suspension Bridge(RYSB) under vehicle and environmental loading during the first-year-service is analyzed.The feature of the fatigue stress amplitude of steel box girders under normal traffic load,heavy trucks and typhoon load,as well as the correlation between strain and temperature varying based on real-time monitoring of temperature histories,were studied.The results show that monitoring systems of local strain in health monitoring systems of RYSB can provide effectively the information on fatigue stresses.Amplitudes of the equivalent fatigue stress on the monitoring locations of the bridge are currently low,mainly due to the traffic loading and temperature varying.There exists significant correlation between varying temperature and mean value of fatigue stress.Effect of the passing of heavy trucks on bridge fatigue is remarkable since the value of the accumulative fatigue damage generated by heavy trucks is 10 to 100 times larger than that by normal traffic.Therefore,overloading and its effect on fatigue accumulative damage due to heavy trucks or overloaded vehicles need to be monitored and close attention is needed.