轨下胶垫频变黏弹性对轨道交通箱型梁动力响应影响分析

Analysis of influence of frequency-dependent viscoelasticity of underrail rubber pad on dynamic response of rail transit box girder

为探讨轨下胶垫频变黏弹性对轨道交通箱型梁动力响应影响规律,以WJ-7B型轨下胶垫(URRP)为研究对象,采用FVMP参数模型表征其频变黏弹性,建立考虑轨下胶垫频变黏弹性的车−轨−桥垂向耦合频域分析模型,运用虚拟激励法计算轨道交通箱型梁随机动力响应。研究结果表明:轨下胶垫的频变黏弹性表现为模量与损耗因子均随频率增大而增大,且增大幅度逐渐变缓;轨下胶垫频变黏弹性对[0,20)Hz频段的车−轨−桥耦合动力响应影响较小;刚度频变导致总动柔度及其相位在较高频段向高频迁移;损耗因子频变仅会降低较高频段固有频率附近的动柔度和相位角幅值;箱型梁各输出点在不同工况下的动力响应规律一致,刚度频变导致动力响应主频向高频迁移,损耗因子频变导致动力响应在固有频段附近有所降低;与轨下胶垫力学性能参数(刚度、损耗因子)取定值相比,考虑轨下胶垫频变黏弹性会导致箱型梁动力响应在[20,54)Hz与[177,200)Hz频段偏低,在[54,137)Hz频段偏高。

In order to discuss the influence of frequency-dependent viscoelasticity of under-rail rubber pad(URRP)on the dynamic response of rail transit box girder,taking the URRP of WJ-7B as the research object,FVMP parameter model was used to characterize the frequency-dependent viscoelasticity of URRP,and a vertical coupling frequency-domain analysis model of vehicle−track−bridge considering the frequency-dependent viscoelasticity of URRP was established.The random dynamic response of rail transit box girder was calculated by the virtual excitation method.The results show that the frequency-dependent viscoelasticity of the URRP shows that its modulus and loss factor both increase with the increase of frequency,and the increasing amplitude gradually slows down.The frequency-dependent viscoelasticity of the URRP has little influence on the dynamic response of vehicle-rail-bridge coupling in the frequency band of[0,20)Hz,and the frequency-dependent of stiffness causes the total dynamic flexibility and its phase to shift to high frequency in the higher frequency band.The frequency-dependent of loss factor only reduces the dynamic flexibility and phase angle amplitude near the higher natural frequencies.The dynamic response law of each output point of the box girder under different working conditions is consistent,and the frequency-dependent of stiffness causes the shift of the main frequency of dynamic response to high frequency,and the frequency-dependent of the loss factor leads to the dynamic response to be reduced near the natural frequency band.Compared with the fixed value of mechanical property parameters(stiffness and loss factor)of the URRP,considering the frequency-dependent viscoelasticity of URRP,the dynamic response of the box girder will be lower in the frequency band of[20,54)Hz,[177,200)Hz,and higher in the frequency band of[54,137)Hz.