中低速磁浮轨道-桥梁系统竖向振动传递特性研究

中低速磁浮交通作为一种新兴的交通方式,其轨道结构形式与传统轮轨交通的轨道有较大的区别。为了研究中低速磁浮交通线路中轨道-桥梁系统竖向振动特性,基于某中低速磁浮试验线,以20m预应力混凝土简支梁为研究对象,建立轨道-桥梁系统竖向振动传递有限元模型并进行振动传递特性分析,随后探讨了激励位置,扣件竖向刚度,轨枕间距对系统竖向振动传递特性的影响。研究表明:系统的位移导纳存在两个峰值,频率分别对应为系统的整体一阶竖弯和F轨的局部一阶竖弯;随着考察点与荷载激励点距离的增大,在F轨局部一阶竖弯频率之后,F轨的位移导纳幅值变化不显著;激励位于扣件处时,在100~200HzF轨的位移导纳振动幅值要大于激励位于非扣件处时;扣件刚度和轨枕间距均会影响轨道结构的局部刚度,从而影响F轨的局部一阶竖弯频率值和在此频率点处的F轨位移导纳幅值;F轨的局部变形较明显,建议在后续的时域磁浮车桥耦合振动模型中应考虑F轨的影响。

Vertical vibration transfer characteristics of medium-low speed maglev rail-bridge systems

As a new mode of traffic,the track structure form of the medium-low speed maglev traffics is different from that of traditional wheel-rail traffics.In order to study its vertical vibration characteristics,based on a medium-low speed maglev test line,a twenty-meter prestressed concrete simply supported beam was taken as the research object.The finite element model for the vertical vibration transmission of the rail-bridge system was established and the vibration transmission characteristics were analyzed.Then,the influence of force location,vertical fastener stiffness and sleeper pitch on vertical vibration transmission characteristics of the rail-bridge system were discussed.The research results show that the displacement admittance of the system has two peak frequencies.These two peak frequencies correspond to the overall first-order vertical bending of the system and the local first-order vertical bending of the F-rail,respectively.With the increase of the distance between the inspection site and the load excitation point,the amplitude of the displacement admittance of the F-rail does not change significantly after the first-order vertical bending frequency of the F-rail.When the excitation is located at the fastener,the amplitude of the displacement vibration of the F-rail in the frequency range of 100-200 Hz is greater than that of the excitation at the non-fastener.The stiffness of the fastener and the distance between sleepers affect the local stiffness of the track structure,thus affect the local first-order vertical bending frequency of the F-rail and the displacement admittance amplitude of the F-rail at this frequency point.The local deformation of F-rail is significant.It is suggested that the effect of F-rail should be considered in the following research of a coupled maglev vehicle-bridge vibration model in time domain.