Damage detection of bridges using response of vehicle considering road surface roughness

Abstract

This paper presents a genetic algorithm based method to identify the damage of girder bridges from the response of a vehicle moving over the bridge. The continuous wavelet transform based method works when the surface is smooth but the identification becomes difficult when the road surface is rough. To deal with this problem, the identification process is formulated as an optimization problem and a guided genetic algorithm is used to search for the global optimal value. The vertical accelerations of the vehicle running over the bridge at the intact and damaged states are used to identify the occurrence and location of the damage. Frequencies of the bridge at the intact and damaged states can be extracted from these responses, from which the frequency-based method can roughly estimate the possible locations of the damage. These locations are not unique as frequencies alone are insufficient to identify the damage location. However these initial results can be used to narrow down the search region on which the genetic algorithm can focus. Numerical study shows that the strategy can identify the damage location for simply supported and continuous girder bridges even though road surface roughness and measurement noise are taken into account.