高架轨道箱梁结构振动试验模型设计与校验

基于π定理和量纲分析法，推导了某32 m高架轨道箱梁结构缩尺模型与原型物理量之间的相似关系，并通过建立动力仿真模型进行计算，验证了相似关系的准确性；以该相似关系指导设计，并通过合理选材，制作了几何相似比为10∶1的轨道箱梁结构缩尺试验模型；通过激振试验获取了缩尺试验模型的模态频率、振型和加速度响应，并与有限元仿真结果对比，验证了缩尺试验模型的有效性；在此基础上利用该缩尺试验模型研究了轨道箱梁结构的振动传递特性。研究结果表明:高架轨道箱梁缩尺模型与原型结构前10阶模态频率误差均小于1%，且由缩尺模型计算结果反演的加速度响应曲线与原型结果趋势一致，模型与原型之间相似关系推导正确；缩尺试验模型实测模态频率与有限元仿真结果的误差均在8.8%以内，各阶模态振型吻合，且实测加速度响应随时间变化趋势与有限元仿真结果一致，制作的高架轨道箱梁结构缩尺试验模型有效；当振动在轨道结构中传递时，扣件和橡胶层对1 000 Hz以上的高频振动具有明显的衰减作用；当振动由箱梁顶板向底板传递时，顶板加速度导纳最大，翼板次之，其次是腹板，底板加速度导纳最小；设计制作的高架轨道箱梁结构缩尺试验模型能够反映原型振动响应的一般传递规律，可用于轨道箱梁结构振动传递特性与控制关键技术研究。 

Design and validation of test model for structural vibration of overpass with track box girder

Based on the π theory and the dimensional analysis method, the similarity relationship of physical quantities between the scale model and the prototype of a 32 m overpass with track box girder structure were deduced. The accuracy of similarity relationship was verified via the dynamic simulation. By considering the similarity relationship as design guides and selecting materials rationally, a scale test model of track box girder structure with a geometric similarity ratio of 10∶1 was constructed. The modal frequencies, vibration modes, and acceleration responses of the scale test model were obtained via the excitation test, and the results were compared with the finite element simulation results to validate the scale test model. Using the model, the vibration transmission characteristics of track box girder structure were studied. Research results demonstrate that the deviations of the first 10 order modal frequencies between the scale model of overpass with track box girder and the prototype structure are less than 1%. The acceleration response curve obtained for the scale model is consistent with that obtained for the prototype. The deduced similarity relationship between the scale model and the prototype is accurate. The errors between the measured modal frequencies of the scale test model and the finite element simulation results are less than 8.8%. In addition, the vibration modes are consistent for all orders, and the measured acceleration response variations with respect to time are consistent with the finite element simulation results. Hence, the constructed scale test model of overpass with track box girder structure is reliable. When the vibration transmits in the track structure, the fasteners and rubber layer have evident attenuation effects for high-frequency vibrations (at frequencies above 1 000 Hz). When the vibration transmits from the top plate to the bottom plate of box girder, the top plate acceleration admittance is the largest, followed by that of the wing plate and then that of the web. The bottom plate acceleration admittance is the smallest. The scale test model of overpass with track box girder structure can reflect the general transmission law of vibration responses of prototype. Therefore, the model can be used to study the vibration transmission characteristics and control technology of track box girder structures. 6 tabs, 20 figs, 31 refs.