钢箱梁的声振特性及影响因素研究

为分析钢箱梁的声振特性，联合锤击试验和统计能量分析（SEA）方法从统计能量分析参数和声振响应两方面进行研究。首先，以某钢箱梁节段10.1 m（长）×4.8 m（宽）×3.1 m（高）]为对象，通过锤击激励获得顶板和底板不同位置的加速度频响函数。然后，建立SEA模型预测钢箱梁的振动声辐射，考察了各板件在100~5 000 Hz频段的模态数，并将加速度频响函数的仿真结果与实测值进行对比。最后，通过数值仿真分析，探讨了结构设计参数（加劲肋和横隔板）对统计能量分析参数和钢箱梁声振响应的影响规律。研究结果表明：除个别频带外，顶板和底板不同测点位置的加速度频响函数没有显著差异；SEA方法可较精确地预测钢箱梁的高频振动噪声，且相比有限元方法具有更高的计算效率；设置加劲肋后，板件的模态密度和输入功率均下降，子系统间的耦合程度降低，但板件的辐射效率增大；设置加劲肋后，顶板和底板的振动速度级在每个频带平均下降8.2 dB和6.7 dB，钢箱梁声功率级在每个频带平均减小3.1 dB（A）；相比加劲肋厚度而言，加劲肋间距对钢箱梁声振响应的影响更大，应优先作为声学优化的主要参数；横隔板可在一定程度上降低板件的振动响应，取消横隔板将导致钢箱梁声功率级在每个频带平均增大1.3 dB（A）。

Vibro-acoustic Characteristics and Influence Factors of a Steel Box Girder

To study the vibro-acoustic characteristics of steel box girders, hammering tests and statistical energy analysis (SEA) were jointly introduced to investigate the SEA parameters and vibro-acoustic responses. First, based on a steel box-girder section (10.1 m (length)×4.8 m (width)×3.1 m (height)), the acceleration frequency response functions of the top and bottom slabs at different locations were measured by applying hammer excitations. Second, an SEA model was built to predict the vibro-acoustics of the steel box girder, in which the modal numbers of different slabs in the frequency range of 100-5 000 Hz were investigated. The prediction model was validated by comparing the simulation results with the hammering test data for the acceleration frequency response functions. Finally, based on numerical simulations, the variations in the SEA parameters and vibro-acoustic responses were investigated for different structural design parameters (e.g., stiffening rib and diaphragm). The research results show that the acceleration frequency response functions of the top and bottom slabs at different locations are close to each other, except in certain frequency bands. The SEA prediction method is highly accurate, while its computational efficiency is low compared with that of the finite-element method. By introducing stiffening ribs, the modal density and input power of the slabs, as well as the degree of coupling between subsystems, are reduced; however, the radiation efficiency of slabs is increased. The vibration velocity levels of the top and bottom slabs at each frequency band decreased on average by 8.2 and 6.7 dB, respectively. The sound power level of the steel box girder is reduced by 3.1 dB(A) on average at each frequency band. The influence of stiffener spacing on the vibro-acoustic responses of the steel box girder is greater than that of the stiffener thickness. Thus, the stiffener spacing should be preferentially regarded as the main parameter when conducting acoustic optimization. The diaphragm can reduce the vibration response of the steel box girder to some extent. The sound power level of the steel box girder can be increased by 1.3 dB(A) on average at each frequency band once the diaphragms are removed.