Research on a bridge damping ratio identification method based on dynamic excitation speed variations

Bridge health monitoring is crucial for ensuring the safety of bridges and extending their service life. Traditional methods for identifying bridge damping ratios are hindered by high costs and complex procedures, highlighting the need for a simpler and more efficient alternative. This paper presents a novel formula for determining bridge damping ratios based on variations in test vehicle speed, aiming to improve identification efficiency and accuracy. By utilising vehicle-bridge interaction (VBI) theory, the analytical response expression of the test vehicle is derived and a band-pass filtering technique is applied to extract the component response corresponding to the first natural frequency of the bridge. The Hilbert transform is used to calculate the instantaneous amplitude of the response, and the relationship between variations in test vehicle speed and the bridge response amplitude is further analysed. Ultimately, a new formula for calculating the damping ratio based on test vehicle speed variations is proposed. Numerical simulation results show that this method can accurately identify bridge damping ratios under varying vehicle speeds, test vehicle damping and noise levels, with errors remaining within a low range and the identification process requiring minimal human intervention. This method provides a new, convenient and efficient solution for bridge health monitoring, with strong practical application value.