Pitching effect of a three-mass vehicle model for analyzing vehicle-bridge interaction

A rigid-mass vehicle model with wheels modelled as unsprung mass is newly proposed considering the pitching effect, which enables us to obtain the first three bridge frequencies from the vehicle's spectrum even in the presence of surface irregularity and damping. As the vehicle moves along the bridge, it generally confronts a bumpy ride due to the presence of surface irregularity. To investigate the up and down of the vehicle body on the identification of frequencies, the use of rigid-mass vehicle model was introduced in the literature. Nevertheless, such a simple model cannot accurately capture the dynamic responses of vehicle and bridge. To this end, this work comes out a three-mass vehicle model by including a rigid-mass and two unsprung masses. Important factors such as unsprung mass, vehicle damping, bridge damping, and surface irregularity are discussed. The pitching effect is unveiled by considering three different locations for installing sensors in the vehicle body. The numerical simulation shows that the proposed vehicle-bridge interaction system is able to identify vehicle's vertical and rotational frequencies if the sensor is installed in the suitable locations of vehicle body.