Optimal integrated multi-sensor system for full-scale structural monitoring based on advanced signal processing

摘要

Modern civil structures as well as loads on them are still too complex to be accuratelymodeled or simulated. Therefore, structural failures and structural defects are NOTuncommon! More and more full-scale structural monitoring systems have beendeployed in order to monitor how structures behave under various loading conditions.This research focuses on how to maximise benefits from such full-scale measurementsby employing advanced digital signal processing techniques.This study is based on accelerometer and GPS data collected on three very differentstructures, namely, the steel tower in Tokyo, the long and slender suspension bridge inHong Kong, and the tall office tower in Sydney, under a range of loading conditions,i.e., typhoon, earthquake, heavy traffic, and small scale wind.Systematic analysis of accelerometer and GPS data has demonstrated that the twosensors complement each other in monitoring the static, quasi-static and dynamicmovements of the structures. It has also been confirmed that the Finite Element Modelcould under-estimate the natural frequencies of structures by more than 40% in somecase. The effectiveness of using wavelet to de-noise GPS measurement has beendemonstrated. The weakness and strengths of accelerometer and GPS have beenidentified and framework has been developed on how to integrate the two as well ashow to optimize the integration.The three-dimensional spectral analysis framework has been developed which can trackthe temporal evolution of all the frequency components and effectively represents theresult in the 3D spectrogram of frequency, time and magnitude. The dominantfrequency can also be tracked on the 3D mesh to vividly illustrate the damping signatureof the structure. The frequency domain coherent analysis based on this 3D analysisframework can further enhance the detection of common signals between sensors. Thedeveloped framework can significantly improve the visualized performance of theintegrated system without increasing hardware costs.Indoor experiments have shown the excellent characteristics of the optical fibre Bragggratings (FBGs) for deformation monitoring. Innovative and low-cost approach hasbeen developed to measure the shift of FBG’s central wavelength. Furthermore, aschematic design has been completed to multiplex FBGs in order to enable distributedmonitoring.In collaboration with the University of Sydney, the first Australian full-scale structuralmonitoring system of GPS and accelerometer has been deployed on the Latitude Towerin Sydney to support current and future research.