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Aspects of the impact-echo method for the detection of voids within metal ducted post-tensioned bridge beams

Aspects of the impact-echo method for the detection of voids within metal ducted post-tensioned bridge beams
Aspects of the impact-echo method for the detection of voids within metal ducted post-tensioned bridge beams
This thesis is concerned with the development of a non-destructive testing technique, namely the impact-echo method, for the evaluation of tendon ducts in post-tensioned prestressed concrete bridges. The impact-echo method has been shown to be useful for damage detection in concrete structures, particularly plate-like structures. However, when it is applied to beam-like rather than plate-like structures the resulting spectra are complex and difficult to interpret. One source of complications is the excitation of cross-sectional modes in the beam. This thesis discusses an investigation into the nature of these modes, and their potential applications for non-destructive testing.
Finite element models have been developed to investigate cross-sectional modes where grouted and ungrouted ducts are present and the results from these are described together with an experimental validation. It is concluded that a shift in the frequency of the dominant cross-sectional mode can be used to identify large ungrouted ducts. In addition, the frequencies of the dominant cross-sectional modes can be predicted for both grouted and ungrouted cases using finite element modelling. Further finite element analysis showed that varying the compression wave speed in grout over a realistic range had minimal effect on the amplitude and frequency of the dominant cross-sectional mode.
McHugh, John Paul
c29d1e17-c2dc-4a2b-9a78-b8d19ede5762
McHugh, John Paul
c29d1e17-c2dc-4a2b-9a78-b8d19ede5762

McHugh, John Paul (1999) Aspects of the impact-echo method for the detection of voids within metal ducted post-tensioned bridge beams. University of Southampton, School of Engineering Sciences, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

This thesis is concerned with the development of a non-destructive testing technique, namely the impact-echo method, for the evaluation of tendon ducts in post-tensioned prestressed concrete bridges. The impact-echo method has been shown to be useful for damage detection in concrete structures, particularly plate-like structures. However, when it is applied to beam-like rather than plate-like structures the resulting spectra are complex and difficult to interpret. One source of complications is the excitation of cross-sectional modes in the beam. This thesis discusses an investigation into the nature of these modes, and their potential applications for non-destructive testing.
Finite element models have been developed to investigate cross-sectional modes where grouted and ungrouted ducts are present and the results from these are described together with an experimental validation. It is concluded that a shift in the frequency of the dominant cross-sectional mode can be used to identify large ungrouted ducts. In addition, the frequencies of the dominant cross-sectional modes can be predicted for both grouted and ungrouted cases using finite element modelling. Further finite element analysis showed that varying the compression wave speed in grout over a realistic range had minimal effect on the amplitude and frequency of the dominant cross-sectional mode.

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Published date: 1999
Organisations: University of Southampton

Identifiers

Local EPrints ID: 47535
URI: http://eprints.soton.ac.uk/id/eprint/47535
PURE UUID: 77cc0e4b-98a9-4650-bd9a-17aac1af66e8

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Date deposited: 07 Aug 2007
Last modified: 13 Mar 2019 21:00

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