Fatigue and U-frame assessment of metallic railway bridges

Start date

March 2020

End date

March 2024


The majority of metallic railway bridges in UK, approximately 10,000 in total, are already exceeding 100 years of age and are approaching the end of their theoretical service life. Replacement of these structures will be extremely expensive and practically impossible unless phased-in over several decades. Therefore, in many cases, rehabilitation and repair options need to be further developed, since they will be more economic and compatible with available resources. However, even this course of action is likely to create severe logistical problems on the railway network, if deemed necessary on a large scale. The principal objective of this project, i.e. better understanding, modelling and prediction of a bridge’s fatigue and U-frame performance, will lead to a more effective use of limited and stretched resources and can reduce the rate of rehabilitation/repair or unwarranted early replacement, thus keeping the railway network operating for longer periods without unnecessary disturbances.

The project reviews critically existing fatigue and U-frame assessment methods used by Network Rail to identify their limitations and inherent uncertainties arising due to the non-standardised designs that were used during construction in the late 19th and early 20th centuries. The project specifically focuses on a better understanding of fatigue in the context of specific materials and assembly methods used in railway bridges, followed by development of modelling techniques that can lead to more accurate prediction of a bridge’s fatigue performance. A major part of the project involves execution of an experimental programme, consisting of small-scale and full-scale static and fatigue tests of materials/components extracted from a disassembled old metallic railway bridge provided by Network Rail, which will be used to benchmark and verify analytical/numerical methods and models and assess their predictive capability and accuracy. The outcomes of this applied research will feed into the standardisation and dissemination of these issues and their integration within existing rules.

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