Dynamic performance verification of the Rędziński Bridge using portable camera-based vibration monitoring systems

Monitoring evolving patterns of the dynamic behaviour of long-span bridges is a critical task in their maintenance and management. For the bridges lacking permanent monitoring systems, ad hoc testing campaigns are sometimes implemented. These are typically costly and utilise wired instrumentation systems requiring a direct contact with the structure, hence they can create risks to the involved personnel and equipment. An alternative solution is explored in our newest paper, reporting successful attempts at obtaining modal damping based on data from optical motion capture systems.

The dynamic response of the biggest one-pylon cable-stayed bridge in Poland - the Rędziński Bridge, was monitored during a short campaign in November, 2020.

Four instrumentation systems were deployed, including a conventional system based on wired accelerometers, a high-end commercial camera-based vibration monitoring system, and two systems utylising a consumer-grade digital camera and motion tracking algorithms based on tamplate matching and optical flow.

To safely accomodate wired accelerometers within the service pathway of the deck, a safety car had to be provided by the bridge operator. This kind of arrangement can significantly increase the cost of a testing campaign.

A comparative study was conducted on the kinematic bridge response obtained with optical vibration monitoring systems against that from accelerometry. A good correspondence was observed between the commercial optical monitoring system and that based on a consumer-grade camera and open-access motion tracking algorithms. An in-depth analysis of modal damping of the lowest six modes was undertaken. It was shown that the optical motion tracking systems can provide data of adequate quality for the damping to be reliably identified, given sufficient excitation levels are ensured. Furthermore, the presented results complement and correct previous efforts targeted at gaining knowledge of the dynamic behaviour of this landmark structure.

More information on this exciting line of research can be found here:
Bocian, M., Nikitas, N., Kalybek, M., Kużawa, M., Hawryszków, P., Bień, J., Onysyk, J., Biliszczuk, J., Dynamic performance verification of the Rędziński Bridge using portable camera-based vibration monitoring systems, Archives of Civil and Mechanical Engineering 23, 40, 2023.