基于实测的苏通大桥疲劳寿命评估

Fatigue Evaluation of Sutong Bridge Based on Actual Measurement

通过分析苏通大桥钢箱梁疲劳关键部位的实测应变时程,研究了其在正常运营阶段的应力谱的特征和疲劳状况预测。由测得的应力时程可知,绝大部分时刻的应变值都在40με以内,但重车过桥时的瞬时应变值可达120με,远大于一般车辆。由应力谱分析可知,苏通大桥钢箱梁顶板及索梁钢锚箱处应力水平较高。由名义应力法计算可知,苏通大桥钢箱梁疲劳寿命最短的部位为顶板与U肋焊缝,为188年。以目前的交通量和结构状况,苏通大桥不会发生疲劳破坏。

Through analyzing measured strain-time data of typical fatigue places on Sutong bridge,this paper studies its stress spectrum characters under daily traffic and predicts its fatigue life.Measured strain time-data shows that at most times its strain is below 40 με,but instantaneous strain can reach 120 με when heavy trucks pass the bridge.Through analyzing stress spectrum,it can be seen that roof of the box girder and cable-girder anchor box own higher stress level.Using nominal stress method,the shortest fatigue life of box girder of Sutong bridge is 188 years and the most dangerous place locates at the weld joint of roof and U-shaped rib.In sum,Sutong bridge won＇t occur fatigue failure under present traffic and structure situation.