OPERATIONAL MODAL ANALYSIS FOR BRIDGE ENGINEERING BASED ON THE DYNAMIC TRANSMISSIBILITY MEASUREMENTS

The dynamic transmissibility is equal to the ratios of mode shapes when approaching the system poles. On the basis of the unique property, transmissibility matrix is formulated by combining vibration response transmissibility functions under multiple vibration conditions, and the system poles are achieved by taking the Singular Value Decomposition (SVD) for transmissibility matrix. The proposed method is further employed to identify the mode shapes. The aim of this paper is to analyze its application to the modal parameters identification of structures under natural excitation. A numerically simulated beam is used to investigate the robustness of the method to harmonic excitations, and the result indicates that the method reduces the risk to identify the spurious modes induced by the presence of harmonics. Furthermore, the ambient vibration test data of a real bridge is adopted to extract the modal parameters. The field results are compared with those obtained from finite element analysis, and stochastic subspace identification. It has shown that the technique is capable of identifying the modal parameters of real bridges.