Technology News

Smart sensors for bridge defects

Newly developed smart sensors that detect stresses and strains in bridge concrete are to be tested in NSW this year

A NSW Smart Sensing Network (NSSN) project has developed smart fibre optic sensors that can monitor corrosion in concrete structures and help extend the service life of a bridge.

The project’s chief investigator Dr Ali Hadigheh says the high-performance fibre optics are cost-effective and can check for strain, cracks and corrosion in reinforced concrete bridges.

“There are many bridges in Australia that are exposed to harsh conditions such as salty water and temperature fluctuations which, in some cases, can lead to severe deterioration,” he says.

“Increasing traffic load, rising sea levels and increased atmospheric CO2 due to climate change are all exacerbating structural deterioration, highlighting the need for continuous health monitoring of bridges.”

Hadigheh says early detection of steel corrosion in reinforced concrete structures can enable early, efficient and cost-effective interventions.

“Our sensing technology and machine learning models enable accurate and early detection of defects in reinforced concrete bridges using only a single fibre Bragg gratings (FBGs) sensor, reducing the cost and simplifying the data analysis process,” he says.

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“A FBG is like a tiny mirror inside an optical fibre that reflects only a specific wavelength of light. It can be used to measure strain, temperature, or pressure in structures like bridges or pipelines by detecting changes in the wavelength of light reflected.”

The Grand Challenge project team also tested the fibre optic sensors in a digital model of a concrete bridge. The sensor prototypes were found to be capable of capturing and modelling reliable structural analytics in real-time. The unique digital model is now being used as a teaching resource in a University of Sydney Civil Engineering course, with hopes that it will be rolled out to university students across Australia.

Transport for NSW (TfNSW) senior bridge engineer Dr Hamid Fatemi says TfNSW will test the sensors in a real-world application.

“TfNSW is hoping to trial the NSSN’s technology this year through a real-time corrosion data acquisition system on the Yamba Road bridge, which spans the Oyster Channel in northern NSW,” Fatemi says.

“When the bridge next undergoes maintenance work, we’re aiming to install fibre optics in the reinstated concrete to collect raw data from the corrosion state of the structure for artificial intelligence analysis, via machine learning, such as reinforcement steel corrosion potential.

“The outcome of this testing could be used to develop future Building Information Models and create future 3D digital replicas (digital twins) of existing bridges and structures in our transport network – using the AI technology to display corrosion or structural conditions in the real time – as and when it occurs.”

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