地震作用下铁路双层结合钢桁混合刚构桥行车安全性

针对特殊地区地震作用下大跨度桥梁行车安全性问题，以某铁路某双层结合钢桁混合刚构桥为工程背景，建立了考虑材料非线性、切向摩擦与轮轨赫兹准确接触关系的列车-轨道-桥梁耦合振动分析模型，并基于ABAQUS-Python软件二次开发，实现了钢轨随机不平顺的施加；选取EL Centro地震波为输入波，分析了强震作用下双层结合钢桁混合刚构桥的损伤演化规律，计算了不同地震强度、不同车速下列车脱轨系数、轮重减载率、车体振动加速度等动力响应指标，分析了关键参数对地震作用下桥上行车安全性的影响规律，提出了该混合刚构桥基于行车安全性能的车速限值。研究结果表明：在罕遇地震作用(0.38g)下，桥梁各构件均出现不同程度的塑性损伤，桥墩破坏区域较大，震后桥梁仍具有一定的承载力；震时列车脱轨系数随地震强度增大而显著增大；车体最大振动加速度与地震强度近似呈线性增长；列车轮重减载率是控制行车安全的关键指标，其峰值与车速呈正相关；当车速为200 km·h^-1，地震强度大于0.10g时，列车轮重减载率存在超限情况，列车在下桥时会出现长时间轮轨分离现象；从行车安全性的角度，在设计地震作用0.20g时，安全车速为160 km·h^-1。

Running safety of hybrid rigid frame railway bridge with double-deck combined steel truss during earthquakes

A hybrid rigid frame railway bridge with a double-deck combined steel truss was taken as the engineering background to investigate the running safety of long-span bridges during earthquakes in special areas. A train-track-bridge coupled vibration analysis model was established by taking into account material nonlinearity, tangential friction, and accurate wheel-rail Hertzian contact relationship. In addition, the application of random irregularities of the rails was realized on the basis of the secondary development of ABAQUS-Python software. The EL Centro seismic wave was selected as the input excitation to analyze the damage evolution laws of the hybrid rigid frame bridge with a double-deck combined steel truss under the action of a strong earthquake. The dynamic response indexes under different earthquake intensities and different train speeds were calculated, including the train derailment coefficient, wheel load reduction rate, and train body vibration acceleration. The influence laws of key parameters on the running safety of the bridge during earthquakes were revealed, and the train speed limit based on the running safety was proposed for the hybrid rigid frame bridge. Research results show that the plastic damage in different degrees occurs on each component of the bridge under a rare earthquake (0.38g), the bridge piers are damaged in large areas, and the bridge still has a certain bearing capacity after the earthquake. The train derailment coefficient during the earthquake rises significantly with the increase in the earthquake intensity. The maximum train body vibration acceleration presents an approximately linear increase with the earthquake intensity. The wheel load reduction rate of a train is the key control indicator to the running safety, and its peak value is positively correlated with the train speed. The wheel load reduction rate of a train exceeds the limit, and wheel-rail separation occurs for a long time at the moment when the train gets off the bridge under the train speed of 200 km·h-1 and the earthquake intensity greater than 0.10g. The safe speed is 160 km·h-1 under 0.20g design earthquake from the perspective of running safety. 2 tabs, 13 figs, 30 refs.