AbstractNorth America’s growing demand for rail transportation capacity, in terms of both train weight and length, has raised concerns regarding the performance of older bridges and has presented the need for improved assessment technologies. A monitoring system composed of discrete and distributed strain sensors combined with a finite-element analysis (FEA) may be able to provide critical insights for assessment. One specific area of concern in older railway bridges is their ability to resist longitudinal forces generated by the braking and acceleration of modern diesel-electric engines. To investigate this, two experimental campaigns were undertaken on a steel railway bridge in North Bay, Canada, using data from sensors and an FEA to study longitudinal force transfer and the impact of rehabilitation with traction bracing. Data from both pre- and post-rehabilitation tests indicated that most axial force in the rail is transferred along its length to a reaction point off the bridge, rather than being transferred immediately into the superstructure. Furthermore, data from the post-rehabilitation tests suggested that the added traction bracing did not significantly affect bridge behavior. Overall, the results demonstrate how field monitoring using conventional and fiber optic strain sensors can be used to assess force transfer between the rail and a superstructure, which could be used as a first step in assessing whether a bridge requires longitudinal strengthening prior to a more comprehensive assessment.

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