Mechanism, annoyance and control of noises generated from modular expansion joint in highway bridges

本研究旨在探讨公路桥梁中车辆通过模块式伸缩缝所产生的环境噪声的产生机理、烦恼与控制。主要研究成果如下：1.在足尺模型上对模块式膨胀节的噪声产生机理和控制进行了试验研究。对汽车在模型上行驶时的噪声和振动进行了测量。结合模型的声学和动力学特性测试，得出结论：接头顶部的噪声可能是由于密封橡胶件间隙内气压的突然变化引起的，而接头底部的噪声可能是由中间梁振动声辐射引起的。并对所提出的噪声控制措施的效果进行了实验研究.对一座非组合工字形钢梁桥和一座带模块式伸缩缝的PC箱梁桥进行了噪声和振动的现场测试。在每种情况下，当不同类型的车辆以不同的速度通过接头时，在桥梁上方和下方的几个点测量噪声。阐明了噪声传播的非平稳特性以及桥梁、车辆和接头类型的影响。通过对A滤波声压谱及其非平稳特性的研究，探讨了环境噪声问题的可能来源.在实验室环境下，通过心理声学实验对模块化关节噪声的烦恼度进行了研究，以识别烦恼度噪声成分。

The objective of this research is to investigate the mechanism, annoyance and control of environmental noises generated by vehicle passage through modular type expansion joint in highway bridges. The research results are summarized as follows.1. The mechanism and control of noise generation for modular expansion joints were investigated in experiments on a full-scale model of the joint. Noise and vibration of the joint model were measured when a car was running over the model. It was concluded, based on this measurement together with tests of the acoustic and dynamic characteristics of the joint model, that the noise from the top of the joint could be attributed to a sudden change in the air pressure in the gaps formed by the sealing rubber elements, and the noise from the bottom was probably caused by sound radiation from vibration of the middle beams. Effects of some proposed noise control measures were also investigated experimentally.2. Field measurements of noise and vibration were conducted in a non-composite I-shaped steel-girder bridge and in a PC box girder bridge with modular expansion joints. In each case, the noise was measured at several points above and below the bridge when different type of vehicles passed over the joint with different speeds. The non-stationary characteristics of noise propagation in the field and effects of bridge, vehicle, and joint types were clarified. Possible sources of environmental noise problem were also discussed by studying the A-filtered spectra of sound pressures and their non-stationary characteristics.3. The annoyance of field-measured noises of modular type joint was also investigated by psychoacoustic experiment in a laboratory in order to identify the annoying noise components.