Monitoring the health of bridges using accelerations from a fleet of vehicles without knowing individual axle weights

This paper proposes a new indirect bridge structural health monitoring concept that uses acceleration data from a fleet of different vehicles with unknown weights. When a vehicle passes the bridge, the vertical displacement under its axles can be inferred from its vertical accelerations. This displacement, termed the "apparent profile", contains two components: bridge profile elevations and bridge deflections under the axle. The two deflection component can be used to find the moving reference influence function (MRIF), defined as the deflection at a (moving) reference point due to a unit load at another point, moving at the same speed. The MRIF can be found when all axle weights are known. In this paper, a new method is proposed to obtain road profile and bridge health condition from the vehicle acceleration, without knowing individual axle weights. Numerical simulation results show that the inferred bridge profile changes when the bridge health condition changes. The difference can be used as an indicator of bridge damage and is illustrated here through an example of bearing damage.