Analysis of bridge dynamic load test based on millimeter wave radar

This study proposes a millimeter-wave radar telemetry method for measuring bridge dynamic deflection, addressing limitations in traditional dynamic strain measurement methods. The method was validated through dynamic load tests on a bridge in Shunyi, focusing on comparing the calculated impact coefficients. The results revealed that the measured first-order modal frequency of 5.664 Hz exceeded the theoretical value of 4.712 Hz, indicating greater structural stiffness. The forced vibration frequency at speeds of 20 km/h, 30 km/h, and 40 km/h consistently matched the 5.664 Hz value. Impact coefficients were also analyzed, with measured values of 0.133, 0.088, and 0.183 for the respective speeds, averaging 0.135, which is lower than the theoretical average of 0.258, suggesting favorable driving conditions. The study identified a ratio of 1.12 between the dynamic strain and deflection amplification coefficients, offering insights into the dynamic behavior of simply-supported bridges. The millimeter-wave radar method demonstrated high accuracy in calculating impact coefficients and proved less sensitive to external environmental conditions, making it a robust tool for dynamic deflection testing. These findings indicate that the proposed method provides a precise and comprehensive assessment of bridge structural dynamics.