直线电机列车作用下高架桥的动力响应分析

Dynamic Response Analysis of Elevated Bridge under Linear Induction Motor Train

建立直线感应电机(LIM)运载系统中列车与高架桥梁的动力相互作用空间分析模型,它由车辆模型和有限元桥梁模型组成。对具有2个转向架的4轴LIM列车车辆建立27个自由度的车辆动力模型。通过对有限元桥梁模型采用模态综合技术,以轨道不平顺作为系统的激励源,建立LIM列车和高架桥梁的耦合运动方程组,并编制计算分析程序。以一座3跨30 m简支梁高架桥为例,模拟LIM列车上桥、出桥的全过程,计算分析高架桥梁的自振特性及其在LIM列车通过时的动力响应特点。研究表明:由LIM列车引起的桥梁横、竖向位移响应值较小,远小于铁路规范的容许值;桥梁的竖向挠度主要受列车的重力荷载控制;桥梁最大横向位移响应出现在墩顶处,随着墩高和车速的增大而增大。

A three-dimensional dynamic interaction model of the linear induction motor （LIM） systems with the elevated bridge is established, which is composed of the linear-motor-driven train model and the finite element bridge model. Each 2-bogie 4-axle vehicle in a LIM train is modeled by a 27-degrees-of-freedom dynamic system. By applying a modal superposition technique to the bridge only and using the measured track irregularities samples as the self-excitations of the train-bridge system, the equations of motion are established and a computer code for analyzing the dynamic responses of the elevated bridge and the LIM train is developed. The proposed framework is then applied to a real 3-span elevated bridge with 30 m simple-supported girders. The whole histories of the LIM train passing through the bridge are simulated on computer. The natural frequencies and mode shapes of the bridge are analyzed. The dynamic responses of the elevated bridge under the running LIM train are computed. The numerical results show that the lateral and vertical displacement responses of the bridge induced by the LIM train are quite smaller than the allowable values. The deflections of the bridge are mainly controlled by train＇s gravity loading. The maximum lateral displacements of the bridge occur at the top of piers and increase with the height of piers and train speed.