Use of mode shape ratios for pier scour monitoring in two-span integral bridges under changing environmental conditions

Malekjafarian, Abdollah; Prendergast, Luke; OBrien, Eugene J.

Abstract

In this paper, a novel pier scour indicator is introduced, which uses the ratio between mode shape amplitudes identified at two points on an integral bridge structure to monitor the progression of scour erosion. The Mode Shape Ratio (MSR) is investigated as an additional parameter to complement the use of changes in natural frequency as a scour indicator. The approach is demonstrated using numerical modelling and the MSR is extracted from acceleration signals arising in the structure due to modelled ambient and vehicle-induced vibrations. The MSR shows higher sensitivity to scour erosion than the more commonly researched natural frequency. Furthermore, the variation in MSR under temperature fluctuations is inversely related to that of frequency, in that it increases with increasing temperature whereas frequency decreases with increasing temperature. This inverse relationship potentially enables the separation of the scour effect from the temperature influence on the dynamics of the system.

Citation

Malekjafarian, A., Prendergast, L., & OBrien, E. J. (2020). Use of mode shape ratios for pier scour monitoring in two-span integral bridges under changing environmental conditions. Canadian Journal of Civil Engineering, 47(8), 962-973. https://doi.org/10.1139/cjce-2018-0800

• Journal Article Type: Article
• Acceptance Date: Sep 1, 2019
• Online Publication Date: Sep 11, 2019
• Publication Date: 2020-08
• Deposit Date: Sep 14, 2019
• Publicly Available Date: Sep 24, 2019
• Journal: Canadian Journal of Civil Engineering
• Print ISSN: 0315-1468
• Electronic ISSN: 1208-6029
• Publisher: NRC Research Press
• Peer Reviewed: Peer Reviewed
• Volume: 47
• Issue: 8
• Pages: 962-973
• DOI: https://doi.org/10.1139/cjce-2018-0800
• Keywords: Civil and Structural Engineering; General Environmental Science
• Public URL: https://nottingham-repository.worktribe.com/output/2616463
• Publisher URL: https://www.nrcresearchpress.com/doi/abs/10.1139/cjce-2018-0800#.XYoQqShKiUk