Impact of track irregularities and damping on the fatigue damage of a railway bridge deck slab

Abstract

The structural response of reinforced concrete slabs in railway bridges is strongly influenced by local dynamic effects and, therefore, detailed calculations of internal forces have to be performed for a realistic fatigue assessment. In this context, this paper discusses the influence of track irregularities and modal damping coefficients in the dynamic response and fatigue behaviour of a railway bridge deck slab. For that purpose, track irregularities were measured (at different instants of time) and damping coefficients were determined based on acceleration records for passing trains in a real bridge. The bridge behaviour was calculated using a train–bridge interaction methodology, considering calibrated numerical models of the viaduct and the train. The fatigue damage was quantified through the linear damage accumulation method. This methodology allowed to understand the way track irregularities and damping coefficients affect the magnitude of applied bending moments and fatigue damage in the slab.

Keywords:

• Concrete bridge deck
• train–bridge interaction
• track irregularities
• modal damping
• dynamic analysis
• fatigue analysis

Acknowledgements

The authors also acknowledge: the information provided by REFER; the support provided by CSF (Centre of Competence in Railways of the Faculty of Engineering of the University of Porto); the assistance of Mr Nuno Pinto (technician of the LESE laboratory) during the experimental tests.