轨道约束对铁路减隔震桥梁地震响应的影响

轨道是限制铁路桥梁减隔震装置在地震中发挥耗能作用的一个可能因素。为了分析轨道约束对铁路减隔震桥梁地震响应的影响,以高速铁路客运专线上两座采用不同减隔震装置的32m简支桥梁为对象,用非线性弹簧单元模拟道床的纵向位移阻力关系,建立地震作用下桥梁与轨道共同作用的线桥一体化计算模型,对其进行弹塑性地震响应分析。结果表明:轨道对铁路减隔震桥梁纵向自振频率的影响不可忽视,影响程度与道床阻力系数有关,随着道床阻力系数增加,结构的自振频率增大;轨道约束虽然对墩底的最大地震剪力影响不大,但对桥梁纵向地震位移和减隔震装置变形的影响出现增大和减小两种现象,设计时应考虑轨道约束产生的不利因素,适当提高相邻梁间的结构允许相对变形要求。

Effect of Rail Restraints on Seismic Responses of Cushioning Railway Bridges

The track structure is a possible factor limiting the energy dissipation function of cushion seats of a railway bridge in earthquake.In order to analyze the effects of rail restraints on seismic behavior of railway bridges equipped with cushion seats,two 32 m-span simply-supported beam bridges of dedicated high-speed passenger railway lines installed with different cushion seats were taken as the objects for study.The longitudinal displacement-resistance relationship of roadbeds were simulated with nonlinear spring elements.The rail-bridge model was established,which was under the coaction of rail and bridge in earthquake.Elastic-plastic seismic responses were analyzed.The research results show as follows:The influence of the track structures on the natural frequencies of vibration of railway bridges with cushion seats cannot be ignored,and the degree of influence changes with the roadbed resistance,i.e.,the higher the roadbed resistance coefficient,the higher the natural frequency of vibration of the track structure;the influence of track restraints on the maximum seismic shear forces at the bottom of piers is small,the influence on longitudinal seismic displacements of girders and on deformations of cushion seats may be subject to both increase and decrease;unfavourable factors caused be track restraints should be taken into consideration in seismic design of railway bridges,requirements for allowable displacements between adjacent girders should be intensified adequately.