Experimental Demonstration of a Mode Shape-Based Scour-Monitoring Method for Multispan Bridges with Shallow Foundations

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Title: Experimental Demonstration of a Mode Shape-Based Scour-Monitoring Method for Multispan Bridges with Shallow Foundations
Authors: Malekjafarian, AbdollahKim, Chul-WooO'Brien, Eugene J.Fitzgerald, Paul C.et al.
Permanent link: http://hdl.handle.net/10197/12040
Date: Aug-2020
Online since: 2021-03-12T11:20:36Z
Abstract: This paper experimentally investigates a vibration-based scour monitoring approach applicable to bridges with multiple simply supported spans on shallow foundations. A monitoring strategy based on the relative changes in pier-mode shape amplitudes due to scour is postulated. The first global mode shape of a bridge structure with multiple spans is extracted from acceleration measurements using an output-only approach, frequency domain decomposition (FDD). The relative changes of the pier-mode shape amplitudes under scour are then tracked. Here, each pier-mode shape value is compared with the mean values of the remaining piers in a process that creates a mean-normalized mode shape (MNMS). The approach is demonstrated on a scaled model of a bridge with four spans, supported on sprung foundations, where scour is simulated by the replacement of springs, with springs of lower stiffness corresponding to a reduction in foundation stiffness. It is shown that at a given “scoured” pier, significant increases in the MNMS value occur, suggesting that the location of the scour can be identified. The magnitude of the MNMS at a given pier also increases with an increase in stiffness loss due to scour. In practice, the approach would work best by carrying out a visual inspection of the bridge to establish the initial health condition at the time of sensor installation. After this initial process, the bridge can be monitored remotely for scour on an ongoing basis.
Funding Details: Science Foundation Ireland
Type of material: Journal Article
Publisher: American Society of Civil Engineers (ASCE)
Journal: Journal of Bridge Engineering
Volume: 25
Issue: 8
Copyright (published version): 2020 ASCE
Keywords: Bridge scourAccelerationsMode shapeDamage detectionSHMVibrations
DOI: 10.1061/(asce)be.1943-5592.0001586
Language: en
Status of Item: Peer reviewed
ISSN: 1084-0702
This item is made available under a Creative Commons License: https://creativecommons.org/licenses/by-nc-nd/3.0/ie/
Appears in Collections:Civil Engineering Research Collection

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