关键词: 斜拉桥, 运行模态分析, 多参考点稳定图, 自然激励技术, 特征系统实现算法, 增强频域分解

Abstract:

As it is easy for the operational modal analysis with unkown excitation to miss true modes and produce spurious modes,an improved multiple reference degrees of freedom( DOFs) stabilization diagram algorithm is proposed based on eigensystem realization algorithm. In this algorithm,by setting different reference DOFs in each group of data,the modal parameters are identified by means of the natural excitation technique in junction with the eigensystem realization algorithm. Then,the most accurate modal parameters are determined with damping ratio,observability matrix-based consistent mode indicator and modal amplitude coherence as the identification indexes. Finally,the proposed algorithm and the enhanced frequency domain decomposition method are both evaluated by means of the modal identification of the measured data of a long-span cable-stayed bridge,the Yamen Bridge. The results show that the proposed algorithm is capable of accurately identifying the low modes,thus providing a good basis for finite element model updating.

Key words: cable-stayed bridge, operational modal analysis, multiple reference DOFs stabilization diagram, natural excitation technique, eigensystem realization algorithm, enhanced frequency domain decomposition