Dynamic identification of an aging prestressed concrete bridge using heavy vehicle excitation

Non-destructive evaluation of aging infrastructures can be useful in evaluating the safety and assuring uninterrupted operation during earthquakes and other natural hazards. Due to the lack of information regarding the structural and material properties, non-destructive evaluation of aging bridges in operation becomes further challenging. This is because numerical modeling using structural mechanics approach is associated with large uncertainties. Such uncertainties can be reduced by dynamic identification methods. Vibration properties of such bridges inferred from dynamic identification can be used to update finite element models of such bridges, which can subsequently be used in safety evaluation. We present a case study of such an application on a 420 m long prestressed concrete bridge. Traffic induced accelerations measured on the bridge deck are used to infer vibration frequencies of the bridge using parametric as well as non-parametric system identification methods. Vibration frequencies inferred from system identification were then used to update the finite element model of the bridge. The results show that vehicle induced vibrations can effectively identify the fundamental vibration frequency of the bridge while higher mode frequencies and damping ratios are more challenging to identify.