Structural Dynamic Monitoring Via Hilbert Enhanced Phase-Based Method

Structural state identification can be realized by monitoring the dynamic behavior changes of the structure. For purpose of recording the structural response for subsequent analysis and research, a certain number of physically attached transducers are applied to these monitoring tools. In addition, the traditional sensing system also includes typical components such as wires, signal conditioners, wireless receivers, the data acquisition system and so on. However, the installation of instrumentations will be time-consuming and laborious for large-scale structures, and instrumentation with contact sensors may cause mass load effect for lightweight structure. In recent years, with the rapid development of digital cameras, non-contact sensing technologies based on image processing which has the advantages of high resolution and easy operation have been flourished. In this paper, the Hilbert enhanced phase-based method is used to extract the local structural dynamic motion in the video (image sequence) in a more accurate and efficient manner, and the structure state of the Humen Bridge is identified using the extract information. The Hilbert enhanced phase-based method obtains the structure local motion information by establishing the theoretical relationship between the phase variations and the physical motion. The Hilbert enhanced phase-based method is applied to the captured Humen Bridge image sequence, from which the structural frequency and operational deflection shape of the Humen Bridge are estimated for damage identification. That also proves the feasibility that the non-contact video measurement can realize the state inspection of real structure.