Deflection measurement on vibrating stay cables by non-contact microwave interferometer

The microwave interferometry has recently emerged as an innovative technology, suitable to the non-contact vibration monitoring of large structures. The paper addresses the application of microwave remote sensing to the measurement of the vibration response in the longer cables of two cable-stayed bridges. In order to highlight the reliability and accuracy of the radar technique, the natural frequencies (and the cable tensions predicted from natural frequencies) identified from radar data were compared to the corresponding quantities obtained by using more conventional techniques. The results of the investigation highlight the accuracy and the simplicity of use provided by the microwave remote sensing, as well as its effectiveness to simultaneously measuring the dynamic response of all the stay cables of an array.