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交通荷载引起的桥梁振动辐射低频噪声严重危害居民的身体健康和生存环境,正确把握桥梁振动噪声辐射机理和准确预测声压水平,对评价及降低环境噪声污染具有重要现实意义。结合车桥耦合振动理论和声传播理论,建立了桥梁振动辐射瞬态噪声的有限元-边界元混合求解体系。结合一座三跨钢连续梁桥,对交通荷载作用下桥梁振动产生的瞬态噪声声场特性进行了实验分析和数值模拟。分析结果表明,该方法能够同时反映声场在时域和频域的分布规律,可全面评估车桥振动辐射噪声的声压水平和声场特性,并具有较好的精度。算例中的下承式钢箱梁桥由于桥面板刚度小,声辐射面大,在车辆荷载作用下辐射噪声水平较高,噪声主要由桥面板振动引起。车辆入桥及出桥时的冲击作用只影响桥梁支座附近的声场。桥面附近等高线形状基本为圆弧形,桥面中心线附近的声压大于横断面两侧。
Low frequency noise of bridge vibration radiation caused by traffic load seriously endangers the health and living environment of residents. It is of great practical significance to correctly understand the radiation mechanism of bridge vibration noise and accurately predict the sound pressure level to evaluate and reduce the environmental noise pollution. Combined with the theory of bridge-coupled vibration and sound propagation theory, a finite element-finite element-boundary element hybrid solution system of bridge vibration radiation transient noise is established. Combined with a three-span steel continuous girder bridge, the transient noise characteristics of the bridge under the traffic load are analyzed experimentally and numerically. The analysis results show that this method can reflect the distribution of sound field both in time domain and frequency domain at the same time, and can comprehensively evaluate the sound pressure level and sound field characteristics of the vibration noise of the vehicle axle with good accuracy. In the case of the steel-framed steel box girder bridges, the bridge deck has a small stiffness and a large sound radiation area. The radiated noise level is high under the vehicle load. The noise is mainly caused by the vibration of the bridge deck. The impact of the vehicle entering and leaving the bridge only affects the sound field near the bridge abutment. The shape of contours near the deck is basically arc-shaped, and the sound pressure near the centerline of the deck is larger than the cross-section.