Investigation of Dynamic Coupling Effect on Bridge Frequency Measurement

In this study, a multidisciplinary approach combining a numerical analysis in three dimensions and a laboratory test is developed to investigate the dynamic coupling effect as induced by vehicle-bridge interaction in the indirect measurement. To unveil such dynamic coupling and its influence on the frequency measurement, a single degree-of-freedom test vehicle is exclusively designed with adjustable frequency, which is a low-cost, easy-to-use, and reliable tool for measuring beam frequencies in the laboratory while providing valuable data for validating numerical models, calibrating sensors, and evaluating bridge performance. From the multidisciplinary analysis, the shifts of frequencies for both vehicle and bridge are consistently demonstrated as a result of vehicle-bridge interaction effect. Moreover, for the identification of higher-order bridge frequencies, the contact-point response works better than the vehicle's response, even with shifted frequencies being observed in the three-dimensional numerical results. As an extension, a parametric study is conducted numerically to include various practical conditions, including different types and boundary conditions of a bridge as well as pavement irregularity.