In order to analyze the effects of seismic excitations on the running safety of a high-speed train passing a bridge, a train-track-bridge dynamic model considenng seismic loads was set up based on the train-track-bridge dynamic interaction theory. As an example, a simply supported beam with a span of 32 m and bi-block track was modeled, and the dynamic responses of a high-speed train-track-bridge system under seismic excitations were analyzed. The results show that the effects of an earthquake on the dynamic responses of a high-speed train-track-bridge system is significant, and compared with the vertical response, the lateral response of a bridge is influenced gready. The running safety and running stability of a train passing a bridge are affected due to seismic loads. When El Centro seismic waves with a normalized horizontal component of 1. 0 m/s2 and a normalized vertical component of 0. 5 m/s2 are subjected to, the reduction radio of wheel-load exceeds the safety limit if its running speed is greater than 250 km/h, and the derailment coefficient exceeds the safety limit if its running speed reaches to 300 km/h. Therefore, the influences of train speed should be taken into account in evaluating the running safety of a train passing a bridge under seismic excitations.%为分析地震对高速列车通过桥梁时行车安全性的影响,基于高速铁路列车-线路-桥梁动力相互作用理论,建立了考虑地震输入的高速列车-线路-桥梁耦合动力学模型.以跨度32 m的简支箱梁桥和双块式无砟轨道为研究对象,对地震作用下高速列车通过桥梁时系统的动力响应进行了数值计算.结果表明:地震对高速列车-线路-桥梁系统动力响应的影响明显,对桥梁横向振动响应的影响大于对竖向振动响应的影响;地震会降低高速列车通过桥梁时的行车安全性和运行平稳性--在水平1.0 m/s2,竖向0.5 m/s2的规格化El Centro地震波作用下,当列车运行速度超过250 km/h时,轮重减载率超过了安全限值;当列车运行速度达300 km/h时,脱轨系数超过了安全限值.因此,评判地震作用下高速列车通过桥梁时的行车安全性,应考虑行车速度的影响.
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