Damage localization for prefabricated bridges group using the area-ratio of the strain time-history curve

The prefabricated bridges group refer to several medium- and small-span prefabricated beam bridges locating in a continuous elevated corridor. It is usually challenging to accurately localize the damage in all bridges within one group due to the lack of monitoring data of bridges in the healthy state. To address this issue, a damage localization method for prefabricated bridges group is proposed based on the area-ratio of the strain time-history curve. First, using the definition of the bridge strain influence line, an area equation of the strain time-history curve is derived theoretically under a moving load for a simple beam bridge and a continuous beam bridge. Second, a damage localization index is established based on the area-ratio of the strain time-history curve by analyzing the constitutive characteristics of the area equation of the strain time-history curve at each measurement point. On this basis, a normalization method is presented for the damage localization index at all measurement points, and then the normalized index is implemented to accurately localize damage in all bridges. Finally, the effectiveness and anti-noise performance of the proposed method are demonstrated through both numerical examples and experiment. The proposed method does not need historical health data or a finite element model (FEM) as the reference and can transform strain time-history curves with different amplitudes from different positions along bridges into a unified normalized index that relates to structural stiffness changes only, which is especially suitable for structural damage localization of long prefabricated bridges group.