杨浦大桥钢箱梁疲劳应力监测及寿命分析

Fatigue Stress Monitoring and Fatigue Life Analysis of Steel Box Girder of Yangpu Bridge

针对杨浦大桥钢箱梁,进行了疲劳应力的监测分析和疲劳寿命的预测研究。利用实桥布设的应变传感器获取应变时程数据,处理成应力时程数据后,结合雨流计数法技术,得到日应力谱,并通过相关统计分析得到了标准日应力谱。利用标准日应力谱数据和相关疲劳规范,研究了杨浦大桥钢箱梁的疲劳寿命等问题。研究结果表明,由于车辆荷载谱或有限元模型均存在大量的假定简化,利用记录的应变(应力)时程数据进行疲劳寿命评估,为准确可靠的研究方法;主梁最容易发生疲劳破坏的部位是各个构造细部,因为在构造细部处往往会产生应力集中,使该处应力远高于构件其他部位;根据相关疲劳规范,杨浦大桥钢箱梁角焊缝具有良好的抗疲劳性能,不会由于疲劳受力而破坏。

For steel box girder of Yangpu Bridge, fatigue stress monitoring and fatigue life prediction were implemented. Monitoring data of strain-time were obtained from the strain transducer disposed on the bridge. After the monitoring data of stress-time were calculated from the monitoring data of strain-time, the rain flow count method was adopted to obtain day stress spectrum. On this basis and by using correspondent fatigue criteria, fatigue life prediction of steel box girder of bridge was discussed. The research result shows that （ 1 ） utilizing the recorded data of stress-time （strain-time） to estimate the fatigue life of the actual bridge is an accurate and reliable method due to the supposition and simplification of vehicle load spectrum and finite element model; （2） The places which are easy to fail in the beam are the welding conformations because the stress focuses in such conformations which leads to the result that the stress is larger than that of the other places. According to the corresponding fatigue criterion, the welding conformations of steel box girder of Yangpu Bridge have good properties of resisting fatigue and those confornlations will not fail.