Assessment of bridge natural frequency as an indicator of scour using centrifuge modelling.
Journal of civil structural health monitoring
MetadataShow full item record
Kariyawasam, K. D., Middleton, C., Madabhushi, G., Haigh, S., & Talbot, J. P. (2020). Assessment of bridge natural frequency as an indicator of scour using centrifuge modelling.. Journal of civil structural health monitoring, 10 (5), 861-881. https://doi.org/10.1007/s13349-020-00420-5
One of the most prevalent causes of bridge failure around the world is “scour” – the gradual erosion of soil around a bridge foundation due to fast-flowing water. A reliable technique for monitoring scour would help bridge engineers take timely countermeasures to safeguard against failure. Although vibration-based techniques for monitoring structural damage have had limited success, primarily due to insufficient sensitivity, these have tended to focus on the detection of local damage. High natural frequency sensitivity has recently been reported for scour damage. Previous experiments to investigate this have been limited as a result of the cost of full-scale testing and the fact that scaled-down soil-structure models tested outside a centrifuge do not adequately simulate full-scale behaviour. This paper describes the development of what is believed to be the first-ever centrifuge-testing programme to establish the sensitivity of bridge natural frequency to scour. A 1/60 scale model of a two-span integral bridge with 15 m spans was tested at varying levels of scour. For the fundamental mode of vibration, these tests found up to a 40% variation in natural frequency for 30% loss of embedment. Models of three other types of foundation, which represent a shallow pad foundation, a deep pile bent and a deep monopile, were also tested in the centrifuge at different scour levels. The shallow foundation model showed lower frequency sensitivity to scour than the deep foundation models. Another important finding is that the frequency sensitivity to “global scour” is slightly higher than the sensitivity to “local scour”, for all foundation types. The level of frequency sensitivity (3.1–44% per scour depth equivalent to 30% of embedment of scour) detected in this experiment demonstrates the potential for using natural frequency as an indicator of both local and global scour of bridges, particularly those with deep foundations.
Is supplemented by: https://doi.org/10.17863/CAM.54904
Gates Cambridge Trust (Bill and Melinda Gates Foundation Grant number OPP1144), Laing O’Rourke Centre for Construction Engineering and Technology, Cambridge Centre for Smart Infrastructure and Construction (Innovate UK Grant reference number 920035 and EPSRC Grant no EP/N021614/1)
Technology Strategy Board (920035)
Embargo Lift Date
External DOI: https://doi.org/10.1007/s13349-020-00420-5
This record's URL: https://www.repository.cam.ac.uk/handle/1810/307904
Attribution 4.0 International (CC BY)
Licence URL: http://creativecommons.org/licenses/by/4.0/