Wheel size embedded two-mass vehicle model for scanning bridge frequencies

A novel vehicle model is proposed to scan bridge frequencies effectively by incorporating both the size of wheel and the unsprung mass in the formulation of an vehicle–bridge interaction element. For the single-degree-of-freedom sprung mass vehicle model commonly adopted in the literature, either the wheel has been treated as a point or the unsprung mass has been neglected due to simplicity. Nevertheless, when a test vehicle is moving on the uneven pavement, the wheels of finite size and mass cannot avoid suffering a bumpy journey, i.e., the wheels are elevated and lowered. As such, the advanced two-mass vehicle model concerning wheel size comes out for realistic application. It is shown that the bridge frequencies can be scanned up to the fifth frequency with desired accuracy even under a high class of road surface roughness in the presence of vehicle damping, whereas the two-mass vehicle model can identify no more than the first two bridge frequencies in the absence of vehicle damping.