铁路钢板梁桥疲劳及剩余寿命分析

Analysis of Fatigue and Residual Life for Railway Bridge with Steel Plate Girder

在列车荷载作用下,铁路钢板梁桥的腹板间隙处因面外变形容易产生疲劳裂纹,影响桥梁使用安全与剩余疲劳寿命。对某铁路钢板梁桥采用ANSYS进行全桥仿真模拟,通过计算模型计算出关键部位在列车荷载下的应力历程,并与实测结果进行对比分析;并利用S~N曲线、线性累积损伤理论对各个测点的疲劳寿命进行评估。计算和分析结果表明,腹板间隙处在较低应力幅状态下仍会出现疲劳裂纹。因此,建议缩短桥梁的检测年限,并且认为设置止裂孔的维修方法不能有效地阻止面外变形疲劳裂纹的继续扩展;大部分测点的疲劳寿命趋于无限寿命,有个别测点的剩余疲劳寿命只有50年。

Under repeated train load,fatigue crack induced by the out-of-plane deformation initiates easily in railway steel plate girder bridges,which can lead to fatigue failure.Especially,traffic load for existing railway steel girder bridges in China are continuous increasing,fatigue problems caused by out-ofplane deformation become worse.In this paper,ANSYS is used to simulate the whole bridge of a railway steel plate girder bridge,and the stress history of the key parts under the train load is worked out by the calculation model,and compared with the measured results,combined with the measured stress spectrum,fatigue life of measured points is evaluated based on S-N curve and liner damage accumulation theory.The results of calculation and analysis show that fatigue cracks still appear when the web gap is in the state of low stress amplitude.It is suggested to shorten the inspection period of the bridge,and the maintenance method of crack stopping hole cannot effectively prevent the continuous expansion of out of plane deformation fatigue cracks.The fatigue life of most points tends to infinite life,and the remaining fatigue life of some points is 50 years.