Research on rapid identification of bridge damping ratio in vehicle-bridge coupling based on mode shape

Based on the fundamental theory of vehicle-bridge coupling vibration, this study proposes a novel method for identifying the bridge damping ratio from the vehicle-bridge interaction by using the bridge’s mode shape. This study conducts theoretical derivation via indirect measurement techniques and performs numerical simulation analysis using a finite element model built in MATLAB. First, acceleration sensors are used to measure the bridge response caused by a single-axle vehicle crossing; subsequently, band-pass filtering is employed to extract the vibration component corresponding to the bridge’s first-order frequency, and the Hilbert transform is used to identify the first-order mode shape curve. Ultimately, the bridge damping ratio is rapidly identified by leveraging the analytical relationship between the damping and the location of the mode shape’s peak. The effectiveness of the method is verified by theoretical derivations and numerical simulations, with a relative error of only 2% under the baseline condition. More importantly, parametric analysis shows that the method has strong robustness, with the relative identification error remaining within 5% even at a higher vehicle speed of 8 m/s and in a strong noise environment of 20 dB. Compared with traditional indirect methods that rely on iterative calculations, the method proposed in this study provides a more efficient, direct analytical identification approach, offering a novel idea for structural health monitoring based on indirect measurement.