Bridge mode shape reconstruction through a moving vehicle with frequency-synchronized structures

In recent years, the use of moving vehicles to reconstruct the mode shape of bridges has gained considerable interest due to its straightforward operational process. Despite its advantages, this technique is susceptible to the influence of road surface roughness and damping, and is also affected by time-frequency analysis techniques. Comprehensive strategies have been put forward to mitigate the effects of such interferences, including the application of excitations to enhance the signal-to-noise ratio, the employment of auxiliary stationary vehicles, and the reduction of damping through a priori techniques, among others. In order to explore an alternative economical solution, this study proposes to use the mode shape ratio to eliminate the impact of damping. This ratio is calculated in an innovative manner using the residual accelerations from a portable system that features with two auxiliary wheels oscillating at the same frequency as the moving vehicle. In this way, this technique simultaneously reduces the interference caused by the road surface roughness. The effectiveness of this proposed method has been demonstrated through a comprehensive set of numerical simulations across a wide range of parameter configurations. Particular emphasis has been placed on the time-frequency algorithms. The simulation results suggest that the Adaptive Superlet Transform method is a good choice to enhance the accuracy of modal position detection. Furthermore, numerical analyses are also conducted to explore the combined impact of detuned auxiliary wheels and edge effects.