Cover of Interferometric Radar for the Measurement of Structural Deflection of Bridges
Interferometric Radar for the Measurement of Structural Deflection of Bridges
  • Publication no: ABC-AAI005-11
  • Published: 31 October 2011

Owners are driven by safety requirements to monitor and predict the behaviour of their structures with increasing surety. Historically Engineers used deflection and strain measurement but more recently dynamic assessment of full-scale structures using vibration testing is being used to meet the owner’s needs. Generally, this testing requires the installation of many transducers over the structure. The time and cost associated with installation limits the use of structural monitoring and therefore the safety of structures. Microwave interferometry, is a new technology that can monitor both the deflection and vibration of many points on a structure. No contact is required during testing, and the system can be set up within 1km from the structure, and detects static and dynamic deflections of multiple points on the structure down to 0.01mm at up to 50Hz using its radar sensor. This paper studies the use of the microwave interferometry in monitoring of bridge structures for deflection under static and dynamic loading to ultimately monitor the overall health of the bridge. A new move to investigate the deflection "signature" of new bridges after construction to use as a base-line for future monitoring is also discussed. It includes a step by step description of the deployment of the sensor in the field and treatment of the resulting data. Case studies from Australia and around the world will be used to illustrate the information collected with the system and will focus on comparing the technology to existing sensors to bench-mark the system.