Using Variational Mode Decomposition for Frequency Identification in a Two-Span Vehicle–Bridge Interaction System

To address the challenge of closely spaced modes commonly observed in multi-span or two-span bridges, variational mode decomposition is incorporated into the vehicle-scanning method to numerically extract individual bridge frequencies from the test vehicle’s acceleration spectrum through intrinsic mode functions. By comparing the decomposed results with the analytical solutions of a two-span vehicle–bridge interaction system subjected to a two-axle three-mass test vehicle, the efficacy of the finite element method is demonstrated. The parametric study shows that the higher-order bridge frequencies can be identified noticeably under various measurement conditions, even with pavement irregularity and bridge damping.