An Improved Vehicle Scanning Method Based on Contact Point Response

Contact point (CP) response of a passing vehicle can be used for the modal identification and condition assessment of bridges. CP response of a vehicle contains the input from bridge dynamics and is free from the vehicle suspension input or vehicle frequency that may overshadow the bridge modal frequencies. As the CP response is free from the vehicle frequency, the collected signal can provide a more accurate representation of the bridge response. Empirical mode decomposition (EMD) is utilized in this study to compare the performance of CP response with direct and indirect monitoring techniques. The measured CP data are processed through a signal decomposition tool, robust EMD (REMD), enhanced by a soft sifting stopping criterion. A numerical study is performed using the closed-form solutions of CP response to various realistic test scenarios including vehicle speed, measurement noise, and structural damage, on the performance of REMD. This study demonstrated the performance of REMD in signal decomposition, signal demodulation, and the estimation of the instantaneous amplitude and frequency. The advanced time–frequency analysis of the collected signal demonstrates pertinent information related to the bridge condition assessment to the stakeholders and decision-makers.