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Monitoring of Rail Bridge Displacements Using Digital Image Correlation

A. J. HOAG, N. A. HOULT, W. A. TAKE, H. LE

Abstract


Much of North America’s railroad infrastructure was constructed in the late 19th and early 20th century. A single unplanned bridge closure can cost millions of dollars, depending on the length of closure. Determining if and when a bridge will need to be retrofitted or replaced is of the upmost importance for railroad companies. As a result there is a need for monitoring technologies that can provide accurate quantitative data that can be used in the assessment of these structures. Digital Image Correlation (DIC) is a new technology that does not require a fixed point of reference or contact with the structure. DIC can be used to track the movements of regions of interest through a series of images. High speed digital cameras can be used to capture bridge deformations as a train passes over them. Thus DIC can be used as a noncontact sensor to monitor bridge displacements, vibrations, and strains without disruption to the regular rail traffic. A field trial was conducted to assess the accuracy of DIC for monitoring rail bridges. The DIC measurements were compared to conventional monitoring technologies and the results were shown to be in good agreement. DIC was capable of measuring the variations in bridge displacements and frequency due to dynamic train loading. A finite-element model of the bridge was created and updated using the field DIC measurements.

doi: 10.12783/SHM2015/52


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