Rigid-Mass Vehicle Model for Identification of Bridge Frequencies Concerning Pitching Effect

In early 1990s, the concept of vehicle-bridge interaction (VBI) was developed to investigate the dynamic behavior of bridges subjected to moving loads such as high-speed trains. In recent years, the VBI system was further introduced to explore the possibility of identifying bridge frequencies in order to monitor the health of bridges by using a passing vehicle. Among the models of test vehicles, the sprung mass vehicle model with a single degree-of-freedom vehicle body is the most common adopted one due to its simplicity. However, for a test vehicle moving over the uneven pavement, the pitching effect arising from the vertical and rotational movements of the vehicle actually influences the identification of bridge frequencies. Therefore, a rigid-mass vehicle model is proposed in this work to improve the sprung mass vehicle model by including both vertical and rotational deflections. The analytical solutions to the rigid-mass vehicle-bridge interaction system are derived to verify the proposed model, and the numerical examples are provided to investigate the dynamic behavior of the VBI system subjected to road irregularity.