Abstract
This thesis focuses on the time-frequency analysis of the vehicle-bridge dynamic interaction response to identify the time-dependent resonances of railway bridges which are incorporated into a damage detection approach, rather than only system identification. Most of the current system identification techniques applied to bridges are based on the free vibration response analysis. It is known that the bridge free vibration response is sensitive to environmental conditions such as temperature and it is not sufficiently sensitive to damage. Input-output modal analysis or output-only modal analysis are the other most used techniques for the bridge system identification. The train-bridge dynamic response, obtained during passage of the train is potentially more sensitive to damage, but also a more complex signal to analyze. First of all, it is a nonstationary signal that is not valid for modal analysis. In addition to the time-variant nature, the vehicle-bridge dynamic response can show closely-spaced spectral components response. These features disrupt the performance of the most advanced signal processing techniques. This thesis therefore applies a recently developed technique, Wavelet Synchrosqueezed Transform (WSST) to extract the Instantaneous Frequencies (IFs) of the Vehicle-Bridge Interaction (VBI) system response. A comparative study is performed on the various commonly used time-frequency analysis techniques. The obtained results were further validated using field measurements on a real bridge. Subsequently, a concept for damage detection in (railway) bridges based on the instantaneous frequency analysis of the bridge’s forced and free vibration responses is proposed. Within this concept, based on the bridge natural frequency extracted from the bridge free vibration, a healthy baseline is obtained of the bridge forced vibration response. The shape correlation and the magnitude variation are proposed to distinguish between the global characteristics of the bridge baseline induced by variable operational conditions and the local deviations caused by damage. of the baseline deviation is damage, then the magnitude variation can be used as a damage index. The results of the numerical studies show that trains with single suspension systems cause more pronounced changes in the bridge’s frequency response, specifically the Vehicle-Induced Delta Frequency (VIDF) and Damage-Induced Delta Frequency (DIDF), than dual suspension trains.
Original language | English |
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Qualification | Doctor of Philosophy |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 26 Apr 2024 |
Place of Publication | Enschede |
Publisher | |
Print ISBNs | 978-90-365-6037-5 |
Electronic ISBNs | 978-90-365-6038-2 |
DOIs | |
Publication status | Published - 26 Apr 2024 |