渡槽整体结构环境激励模态试验

为获得渡槽整体结构动力特性，开展单向SIMO法、双向MIMO法环境激励模态试验，选用增强频域分解法识别纵向、横向、竖向、横竖双向模态参数。结果表明:2种方法识别出的模态大多数谱峰明显、识别效果较好；纵向模态以排架结构振动为主，槽身整体平动或转动或不动；前4阶横向模态以排架结构振动为主，槽身整体平动或转动或横摇，第5阶模态后，绝大多数以槽身振动为主，排架几乎不动或振动幅度很小；竖向模态以槽身振动为主；横竖双向MIMO法识别出的模态同时包含横向、竖向模态分量；2种方法识别出的模态频率误差较小；从模态识别准确性、信息全面性而言，渡槽整体结构环境激励模态试验选择双向MIMO法优于单向SIMO法。

Modal test for overall structure of aqueduct under ambient excitation

In order to obtain the dynamic characteristics of the overall structure of aqueduct, the modal tests of ambient excitation were conducted by the one way SIMO method and the two way MIMO method. Longitudinal, transverse, vertical and transverse vertical bidirectional modal parameters were identified by the enhanced frequency domain decomposition. The results show that most spectrum peaks have been obviously identified by two methods with satisfactory dentification results of modal parameters. The longitudinal modes and first four transverse modes of aqueduct structure are dominated by the vibration of the bent structure, and the aqueduct body is the translation or rotation or motionless. After the fifth transverse modes, most of them are dominated by the aqueduct body, and the bent structure is barely moving or vibrates very little. The vertical modes are dominated by the vibration of aqueduct body. In addition, the bidirectional modes identified by the MIMO method include both the transverse and vertical components, and the errors of modal frequency identified by both the SIMO and MIMO methods are small. According to the identification accuracy and comprehensive information of modal tests, the two way MIMO method is better than the one way SIMO method for the overall structure of aqueduct.