Uncertainty quantification in operational modal analysis of bridge structure
QIN Shi-qiang1, GOU Hong-ye2, JIA Hong-yu3, PU Qian-hui2
Author information+
1. Hubei Key Laboratory of Roadway Bridge and Structure Engineering, Wuhan University of Technology, Wuhan 400370;
2. School of civil engineering, Southwest Jiaotong University, Chengdu, 610031,
3. Department of civil engineering, Southwest Jiaotong University, Emei, 614202
In order to quantify the uncertainty for operational modal analysis (OMA), two methods were employed to estimate the uncertainty of natural frequencies and damping ratios by using Stochastic Subspace Identification (SSI) as an example. Firstly, mathematical expectation and standard deviation of modal parameters identified from different setups were used to measure its overall size and dispersion, and the overall confidence intervals of modal parameters were constructed. Secondly, a method to quantify the uncertainty of modal parameters obtained from a single setup through matrix sensitive analysis was introduced, and the stabilization diagram with confidence intervals is established. The ambient vibration test of the arch rib of Caiyuanba Yangtze River Bridge was taken as an example. The study shows that the overall confidence intervals is a supplement to the existing single mode to assessing modal parameters. The stabilization diagram with confidence intervals can help testers to distinguish the spurious modes from system modes. Two methods introduced can measure the uncertainty of the modal parameters from overall and local viewpoint, respectively, which provide a basis to assess the credibility of the estimated modal parameters from OMA.
QIN Shi-qiang1, GOU Hong-ye2, JIA Hong-yu3, PU Qian-hui2.
Uncertainty quantification in operational modal analysis of bridge structure[J]. Journal of Vibration and Shock, 2015, 34(8): 193-197
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