Research on Uncertainty of Modal Parameter Identification of Cable-stayed Bridge by Ambient Excitation
In order to analyze the uncertainty of the identification of the modal parameters of a model cable-stayed bridge,the zonal modal tests of the ambient excitation method are carried out.The vertical and torsional modes of the beam,the modes of the tower in-plane and out-plane are tested.Firstly,the influence of non white noise excitation on modal parameter identification is analyzed,and a method of using structural finite element model simulation analysis combined with stability diagram to eliminate false modes is proposed.Secondly,using the eigensystem realization algorithm(ERA)combined with the proposed false mode elimination method,a total of 15 order modes of the whole bridge are identified.Then,peak picking method(PP),orthogonal polynomial method(RP),least squares complex exponential method(LSCE)and stochastic subspace identification(SSI)are used to identify the modal parameters respectively.The modal parameter identification results of each method are compared,and their uncertainties are statistically analyzed.The frequency identification results has minor variability,while the damping and vibration mode have significant variability.Finally,the MONTE CARLO method is used to add noise to the measured frequency response function,and RP method is used to identify the modal parameters.The results show that the uncertainty of the modal parameter identification results is small when the measuring point is located at the position with large mode shape amplitude,and the uncertainty of the modal parameter identification method is greater than that of the noise.
cable-stayed bridgeambient excitationmodal parameter identificationuncertaintyMONTE CARLO method
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万方数据
