桥面坑凼对桥梁冲击效应的影响研究

Study of Impact Effect of Deck Potholes on Bridge

为研究桥面坑凼对桥梁冲击效应的影响,以某空心板梁桥为背景进行动载试验和桥梁挠度监测,对比桥面坑凼形成前、后桥梁冲击系数的变化,并通过车桥耦合动力学仿真分析研究坑凼尺寸和行车速度对冲击系数的影响。结果表明:无桥面坑凼时,桥梁动载试验冲击系数均值为0.182,存在桥面坑凼时,桥梁挠度监测的冲击系数均值为0.828,桥面坑凼对冲击效应有明显的放大作用;存在桥面坑凼时,车桥耦合动力学仿真分析的冲击系数最大值对应的行车速度处于低速区,且与坑凼长度的比值接近桥梁结构的基频,桥面坑凼易使桥梁结构在车辆低速行驶时发生共振,且坑凼越深,冲击系数最大值越大。

The study in this paper focuses on the impact effect of deck potholes on bridges.The case bridge is an existing hollow core beam bridge.Dynamic load tests and deflection monitoring were conducted to investigate the variation of impact factors of the bridge before and after the formation of potholes.The vehicle-bridge coupling was dynamically simulated to analyze the influence of pothole dimension and vehicle travelling speeds on the impact factor.The results show that without potholes,the average impact factor of the bridge gained by the dynamic load test is 0.182,while with potholes,the average impact factor gained by the deflection monitoring is 0.828,indicating that potholes trigger the amplification of impact factor.In the dynamic simulation,with potholes,when the impact factor is the maximum,the vehicle travelling speeds are within the lower range,and the ratio of impact factor and the pothole length approximates the fundamental frequency of the bridge.It is concluded that potholes can cause vehicle-bridge resonance when vehicles passing through the bridge with low speeds,and the deeper the potholes,the greater that maximum impact factor will be.