Potential breakthrough for bridge failure prediction

  • July 20, 2020
Potential breakthrough for bridge failure prediction

A new study led by Kasun Kariyawasam could be a real step forward in addressing the major cause of bridge failure.

What is believed to be the first-ever centrifuge test programme to show how sensitive bridges are to scour – the most common cause of bridge failure around the world – has been conducted by researchers at the University of Cambridge.  The tests also found that bridges with deep foundations have higher frequency sensitivity to scour than those with shallow foundations.

Scour is the gradual erosion of soil around a bridge due to fast-flowing water and is thought to account for half of all bridge failures around the world.

Being able to reliably monitor it could help bridge engineers take timely countermeasures to safeguard against failure.

A paper published in the Journal of Civil Structural Health Monitoring lead-authored by Gates Cambridge Scholar Kasun Kariyawasam describes the development of what is believed to be the first-ever centrifuge-testing programme to establish the sensitivity of bridge natural frequency to different forms of scour in different types of bridges.

A 1/60 scale model of a two-span integral bridge with 15m spans was tested at varying levels of scour. Models of three other types of foundation were also tested in the centrifuge at different scour levels.

Kasun [2016], who is doing a PhD in Engineering, said: “Most of the current techniques to detect scour have limitations related to cost, reliability and robustness and these limitations generally arise from the fact that the scour monitoring sensors have to be underwater. This research studied an alternative monitoring technique, which does not require any underwater sensor installations. It attempts to detect scour by tracking the changes in bridge vibration properties, such as natural frequency. This technique is very appealing because it is a real-time, remote monitoring technique.”

Another important finding is that the frequency sensitivity to “global scour” is slightly higher than the sensitivity to “local scour”, for all foundation types studied in this research.

Kasun says: “Such significant changes in natural frequency give new insights to bridge engineers and allow us to track natural frequencies of bridges to detect scour.”

Professor Campbell Middleton, Laing O’Rourke Professor of Construction Engineering at the University of  Cambridge, who supervised Kasun’s research, said: “Scour of bridge foundations is by far the most prevalent cause of failure of bridges around the world yet, to date, no practical and effective monitoring technique has been devised to give advanced warning of the risk of impending collapse. Various researchers have tried using natural frequency based techniques to detect damage in bridges. However, these have tended to focus on identifying specific local defects, such as cracks or corrosion, and have met with very limited success.

“The technique examined in this paper focusses on characterising changes in the global vibrational response of a bridge due to the loss of soil around piled foundations as a result of scour. Our experimental centrifuge testing programme observed variations in natural frequency of up to 44% as a result of scour which indicates that this approach could, for the first time, provide a predictive tool for warning of impending scour failure in bridges built on piled foundations. This would be a very significant step forward in ensuring the safe operation of our bridge infrastructure.”

Latest News

The process of history-making

Olin Moctezuma-Burns [2020] is keen not to repeat the patterns of some past researchers and to give back to the communities she studies. For that reason she recently co-organised an international gathering of Imagining Futures projects on archiving indigenous and traditional knowledges in Sotuta, Yucatan. The meeting brought together people from Colombia, Peru, Kenya, Tanzania, […]

How might extreme heat contribute to human migration?

Rising temperatures due to climate change are likely influencing human migration patterns, according to a new study co-authored by Gates Cambridge Scholar Dr Kim van Daalen [2018]. The study, led by Rita Issa of University College London, is published today in the open-access journal PLOS Climate. It looks at the role of heat in human […]

Scholar scoops prestigious science innovation fellowship

Freja Ekman has been named one of the 2023 class of Hertz Fellows as the prestigious fellowship celebrates its 60th year. The 15 fellowships in applied science, engineering and mathematics are awarded by Fannie and John Hertz Foundation, a non-profit organisation for innovators in science and technology. Winners will have their graduate studies funded for […]

Scholar hosts first UN communications technology access meeting in India

Gates Cambridge Scholar Pradipta Biswas has hosted a UN meeting on improving access to communications technology – the first ever held in India. The meeting of ITU-T Study Group 9 (SG-9) on “Broadband Cable and Television/Audiovisual content transmission and integrated broadband cable networks”  was held in May at the Indian Institute of Science in Bengaluru […]