由高架箱梁振动产生的桥梁结构噪声是高架线路辐射噪声的重要组成部分。从理论与现场实测两方面研究列车通过时高架轨道箱梁的振动特性。首先利用有限元法建立城市轨道交通高架简支箱梁的三维振动分析模型，分别计算列车以速度为60 km/h、80 km/h、100 km/h和120 km/h通过时，高架轨道箱梁结构的动力响应。将理论模型的计算结果与实测结果进行对比，发现理论模型计算结果和试验分析结果在20 Hz至400 Hz基本上保持一致，最大误差为9.6 dB，说明计算模型满足一定的精度要求。理论模型时域分析的结果表明：同一辆列车经过时各测点振幅值随车速的提高而增大；不同类型列车以相同速度通过时，由于车辆-轨道的耦合作用，列车对轨道和桥梁的冲击作用不同。模态分析结果表明，固有频率高于10 Hz时箱梁振动模态开始呈现截面变形，且随着频率增加，箱梁结构振动形式逐渐表现为构件的弯曲振动。频域分析结果表明，钢轨、轨道板、桥面板、翼缘、腹板和梁底板的振动水平分别为140 dB至160 dB、110 dB至120 dB、110 dB至120 dB、115 dB至130 dB、110 dB至125 dB和105 dB至115 dB，振动幅值随车速的提高而增大。%In order to study the vibration response of the elevated box girders in urban mass transit operation, a 3D model for vibration analysis of a simply supported box-girder is established by FEM. The dynamic responses of the box-girder are obtained with the train traveling at the velocities of 60 km/h, 80 km/h, 100 km/h and 120 km/h. And the dynamical characteristics of the elevated box girder are investigated by field tests. The theoretical calculation results and test results can keep consistent in the frequent range of 20 Hz-400 Hz. The maximum difference is found to be 9.6 dB. It means that the calculation model can meet the requirement of accuracy. The modal analysis results show that mode shapes for the natural frequencies above 10 Hz present sectional deformations, and the vibration pattern of the box girder becomes component’s bending vibration gradually with the frequency increasing. The time domain analysis result shows that when the same train passes, the vibration amplitude at the measurement points will increase with the vehicle’s speed. However, when different trains pass at very close speeds, the impact on bridges are still different because of vehicle-track coupled action. The vibration levels of rail, slab, deck, flange, web and bottom plate are ranged in 140 dB-160 dB, 110 dB-120 dB, 110 dB-120 dB, 115 dB-130 dB, 110 dB-125 dB and 105 dB-115 dB respectively, and the vibration amplitudes increase with the train speed increasing.
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