Evaluating in-service structural behaviour of an operational railway bridge using fibre optic sensing and structural model updating

Multi-girder prestressed concrete bridges are a very common structural form for bridges around the world. Their continued use is expected in the future given the advantages these structures have with respect to speed of construction, reduced maintenance and improved material efficiency. However, the in-service behaviour of these types of structures, such as their load distribution characteristics, support boundary conditions and the contribution of secondary elements, is still not well understood, and few studies have investigated these areas in depth. Gaining better insight into these aspects of bridge behaviour will enable more realistic structural assessment and thus facilitate more targeted maintenance and refurbishment of these bridges. This paper evaluates the in-service structural behaviour of an operational prestressed concrete railway bridge, which has been monitored using a dense network of fibre optic strain and temperature sensors since it was constructed in 2015. In particular, the normalised curvature profiles and the neutral axis positions across the composite solid slab bridge deck may be used to extract information about the bridge's transverse load distribution behaviour, support boundary conditions and the stiffness contribution of secondary elements. Using this information, structural model validation and updating were performed with the goal of providing a more realistic assessment of structural behaviour and structural capacity. The proposed methodology and workflow in this study provide new insights into the real performance of multi-girder prestressed concrete bridges and thus can be used to improve their operation, maintenance, assessment and refurbishment.

Automated summary

Multi-girder prestressed concrete bridges are commonly used around the world due to their advantages in construction speed, maintenance reduction, and material efficiency. However, the in-service behavior of these structures, including load distribution characteristics and support conditions, is not well understood. This study evaluates the structural behavior of an operational prestressed concrete railway bridge, using a dense network of fiber optic sensors to extract information on load distribution, support conditions, and secondary element stiffness. The proposed methodology and workflow provide insights into the real performance of these bridges, aiding in their operation, maintenance, assessment, and refurbishment.