龙卷风作用下大跨度桥梁车-轨-桥耦合振动及行车安全性

为研究龙卷风作用下大跨度桥梁车-轨-桥系统动力响应及行车安全性，首先以Kou-wen三维模型模拟龙卷风速度场，基于准定常理论确定了移动龙卷风作用下车辆和桥梁风荷载时程. 然后，分别采用多体系统动力学和有限元理论建立列车和轨道-桥梁子系统动力方程，基于轮轨空间非线性接触建立风-车-轨-桥系统动力方程，并采用分离迭代法求解系统动力响应. 数值算例中，以某公路铁路两用斜拉桥为研究对象，通过风洞试验和CFD数值模拟确定车辆和桥梁气动力系数，分析了龙卷风移动路径、强度等级和行车速度对车-桥系统动力响应及列车行车安全性的影响. 结果表明：桥梁竖向振动响应比横向显著，且龙卷风竖向风速对桥梁竖向位移起控制作用 . 当车辆经过风荷载最大位置时，车辆的横向和竖向振动响应均达到最大值，且车辆动力响应受龙卷风荷载和桥梁动力响应共同影响. EF1级和EF1.3级龙卷风作用下，列车安全通过的车速阈值分别为180 km/h和114 km/h.

Train-track-bridge Coupling Vibration and Train Running Safety of Long Span Bridge under Tornado

To investigate the dynamic responses of the train-track-bridge system and running safety under tornadoes, the Kou-wen 3D model is used to simulate the tornado wind field, firstly. The time history of wind loads on vehicles and bridges under the action of moving tornadoes is determined based on quasi-definite theory. Then, the dynamic equations of the vehicle subsystem and track-bridge subsystem are established by using the multibody dynamics approaches and finite element method, respectively. The dynamic equations of the wind-train-track-bridge system are established based on the wheel/rail nonlinear contact relationship, and the dynamic response of the systemis solved by the separation iteration method. In the numerical calculations, a road-cum-rail cable-stayed bridge was taken for a case study. The aerodynamic coefficients of bridge and train are determined by wind tunnel test and CFD numerical simulation. The influence of the direction of tornado movement, tornado intensities and running speeds on train-bridge system dynamic response and train running safety is analyzed. The results show that the vertical dynamic response of the bridge is more significant than that of the horizontal, and the vertical wind speed plays a critical role in the vertical displacement of the bridge. When the vehicle passes through the maximum position of wind load, both the lateral and vertical vibration response of the vehicle reaches its maximum value, and the vehicle dynamic response is affected by both tornado load and bridge dynamic response. The maximal running velocity under the EF1 and EF1.3 tornadoes is 180 km/h and 114 km/h, respectively.