Bridge health monitoring using deflection measurements under random traffic

This paper demonstrates the potential to use measured deflection responses of a bridge to random traffic as a means of monitoring its structural health. Three displacement transducers are simulated on the bridge at different locations, providing absolute deflection data. The stiffness profile through the length of the bridge is calculated using these data. Vehicle axle loads are calculated as well as the relative bridge stiffness profile using a combined iteration approach. Axle spacings for each vehicle are currently measured in Bridge Weigh-in-Motion systems and are presumed to be known here. After estimating axle weights for each passing vehicle, the profile of bridge stiffness is calculated from batches of 1,000 vehicles with a focus on detecting any local damage. A moving average filter and a filtering method based on the Blackman window are used to reduce dynamic effects and the influence of noise. This stiffness profile approach is shown to be suitable for both damage location and quantification.