MODAL PARAMETER IDENTIFICATION OF A GIRDER BRIDGE BY FAST BAYESIAN FFT METHOD UNDER AMBIENT EXCITATION

摘要

The Bayesian theory is adopted in modal parameter identification,finite element model updating and damage identification of the structures recently.Fast Bayesian FFT method has obvious advantages on modal parameter identification because it adopts the fast Fourier transform(FFT)of original time-domain data directly.Moreover,the precision of modal parameters can be verified by their posterior coefficients of variation(c.o.v.).In this paper,this method is adopted to process the tri-axial acceleration response of a girder bridge under ambient excitation.In addition to the best estimates of modal parameters,their posterior c.o.v.are also obtained to indicate their precision.Comparisons with the corresponding results from Peak-picking method(PP),Stochastic Subspace Identification(SSI)and Finite Element Method(FEM)indicate that Fast Bayesian FFT is a reliable and competitive approach to identify modal parameters.