共振速度下轨道交通槽形梁结构瞬态噪声分析

Transient Noise Analysis of Rail Transit Trough-shaped Beam Structures under Resonant Speeds

为了进一步研究不同列车速度下的桥梁结构噪声问题,基于有限元-瞬态边界元理论,针对轨道交通30 m简支槽形梁,分析在共振、消振速度下桥梁的振动响应及结构声辐射特性。首先,建立槽形梁振动辐射瞬态噪声的有限元/边界元模型;然后,对简支梁在移动列车荷载下诱发的振动进行分析,得到列车荷载通过桥梁时的共振和消振速度;最终,结合声辐射理论,采用瞬态边界元法研究分析不同列车速度引起的桥梁瞬态噪声声场特性。研究结果表明:列车速度的变化引起桥梁结构的位移幅值出现波动性变化;桥梁结构的振动加速度幅值随着速度的增大而不断增大;桥梁结构辐射噪声的变化趋势与结构的振动加速度变化趋势有一定的相关性;当列车以共振速度通过简支桥梁时,结构动力响应值及辐射噪声值有放大趋势,在附近出现峰值;列车共振速度对桥梁结构的远声场瞬态噪声影响效果较为显著;应有针对性地控制列车速度以改善桥梁结构噪声。

In order to further study the structural noise of bridges under different train speed condition, the structuralnoise and sound radiation characteristics of a rail-transit trough-shaped 30 m-span simply-supported beam are analyzed bymeans of finite element method and transient boundary element theory. First of all, the finite element and boundary elementmodel of the trough-shaped beam is established. Then, vibration of the simply supported beam under moving load excitationis analyzed, and the resonance speed and the vibration suppression speed are obtained. Finally, using the theory of soundradiation combined with the transient boundary element method, the characteristics of the transient noise of the beaminduced by different train speeds are calculated and analyzed. The results show that the train- speed change can causefluctuation of the displacement amplitude of the beam structure. The vibration acceleration of the beam structure increaseswith the increasing of the train speed. Variation of the radiation noise of the beam structure is somewhat correlated with thatof the structure vibration acceleration. When the train is traveling through the beam bridge at the resonance speed, thedynamic response and the radiation noise of the structure will be obviously amplified. The transient noise of the beam bridgestructure is also significant under resonant speed in the far acoustic field. So, the train speed should be controlled in order toreduce the noise of the beam bridge structure.