减振垫刚度变化对U型梁桥系统振动及结构噪声的影响研究

为了研究隔离式减振垫垂向刚度对U型梁桥结构振动及噪声的影响,采用多体动力学和有限元联合仿真的方法建立基于Timoshenko梁模型的车辆-轨道-桥梁刚柔耦合动力学模型,并将理论计算结果与以往文献对比,验证了模型的有效性。基于该模型计算了减振垫垂向刚度不同情况下的桥梁系统振动及噪声响应。结果表明:随着隔离式减振垫垂向刚度的增大,钢轨和轨道板的振动响应都有不同程度的减小,但桥梁结构的振动响应被放大,轨道结构和U型桥梁的振动幅值先是产生明显变化,随后逐渐趋于平缓;隔离式减振垫垂向刚度增加会增大桥梁结构二次噪声,所以应该选取较小的隔振垫刚度以达到抑制U型梁桥结构二次噪声的目的,但过小的垂向刚度可能会放大40 Hz以内低频区域的结构噪声。综合U型梁桥系统振动及结构噪声的计算结果,考虑到工程成本,用于高架结构的隔离式减振垫垂向刚度取为0.067N/mm~3较为合适。

Effect of Stiffness Change of a Vibration-absorbing Pad on the Vibration and Structural Noise of a U-shaped Girder Bridge

In order to study the effect of the vertical stiffness of the isolation damping pad on the vibration and noise of a U-beam bridge structure, this study adopts the method of multi-body dynamics and finite element co-simulation to establish vehicle-track-bridge rigid-flexible coupling dynamics based on the Timoshenko beam model. The model is learned, and the theoretical calculation results are compared with those of previous studies to verify the effectiveness of the model. Based on this model, the vibration and noise responses of the bridge system under different vertical stiffnesses of the cushions were calculated. The results show that as the vertical stiffness of the isolation damping pad increases, the vibration response of the rail and track slab is reduced to varying degrees, but the vibration response of the bridge structure is amplified, as well as the vibration amplitude of the track structure and U-shaped bridge. The value first changes significantly, and then gradually changes more slowly; the increase in the vertical stiffness of the isolation cushion will increase the secondary noise of the bridge structure, so a smaller cushion stiffness should be selected to suppress the secondary structure of the U-beam bridge. A vertical stiffness that is too small may amplify structural noise in the low-frequency region within 40 Hz; integrated U-beam bridge system vibration and structural noise calculation results, considering the engineering cost, are used for isolation vibration reduction of elevated structures. A more appropriate vertical stiffness of the pad is 0.067 N/mm3.