Damage Detection of Bridge Beam Subjected to Moving Loads Based on Energy Ratio from Vibration Response

A methodology to locate and size damage in a beam subjected to moving load is presented in this paper. The presence of damage results in the decrease of stiffness at the point of damage and alters the structural response patterns. In particular, under the same excitation, the kinetic energy near the damage will change more obviously than that where no damage occurs. So the velocity response for a specified time interval by sampling with a time window is obtained for each measurement point. The energy ratio is, in turn, used to build a damage index that represents the ratio of the stiffness parameter of the predamaged to the post-damaged structure. The curve constructed by energy ratios at measurement points is used to identify possible locations and corresponding severities of damage in the beam. The validity of the methodology is demonstrated using data from a numerical example of a simply beam.