移动谐振荷载作用下浮置板轨道的动力响应

在移动谐振荷载作用下，依据周期结构响应的性质，将无限长浮置板轨道响应的问题求解转化到在一块浮置板长度范围内进行，并通过浮置板的位移影响矩阵在频域内实现了钢轨和不连续浮置板的耦合，求得了该范围内钢轨的动力响应，进而以此为基础求得了轨道结构上任意一点的动力响应。结果表明:移动谐振荷载作用下，在移动荷载自身激振频率附近，浮置板轨道位移响应频谱达到峰值；随着移动谐振荷载速度的增大，在频谱上，荷载自身激振频率附近很窄的频段位移响应会有所下降，而在其他大部分频段位移响应会有显著增加；当谐振荷载激振频率与浮置板轨道的固有频率一致时，发生共振现象，在频谱上位移响应的峰值远远大于其他激振频率时响应的峰值；浮置板轨道在移动荷载作用下，存在由荷载周期通过不连续浮置板和扣件而引发的参数激励；当移动谐振荷载激振频率接近有限长浮置板形成驻波的频率时，轨道结构也会产生较大的位移响应。

DYNAMIC RESPONSE OF FLOATING SLAB TRACK DUE TO A HARMONIC MOVING LOAD

Under a harmonic moving load,according to the characteristics of periodic structural dynamic responses,the problem that the dynamic response of the infinite floating slab track(FST) is transformed to be solved within the track range corresponding to one floating slab.Then through the displacement influence matrix of the floating slab,the coupling of the rail and the discontinuous slab is implemented in the frequency domain,and the dynamic response of rail in the range is obtained.Further,based on this,the dynamic response at any point on the track structure is obtained.The calculation results show that: Under the harmonic moving load,the displacement response spectrum's peak of FST appears near the excitation frequency of the moving load;with the increase of the loading velocity,there will be a decrease on the displacement response spectrum in a very narrow frequency band around the excitation frequency of the moving load,while there will be a significant increase in most of other frequency bands;when the excitation frequency of the moving load is equal to the nature frequency of FST,the resonance occurs,the displacement response spectrum's peak is much larger than those under other excitation frequencies;due to the moving load periodically pass through the discontinuous slabs and the fasteners,there exists a parametric excitation;when the load excitation frequency is close to the frequency of the formation of standing waves due to the slab's discontinuity,the track structure will also have a greater displacement response.