Fatigue design of metallic railway bridges in France at the end of the nineteenth century

Abstract

Among more than 25 000 bridges and viaducts in the French railway network, more than 2000 metallic bridges have been in service for over a century, and they need adapted measures for their maintenance. Due to the increase in rolling speed and axle load, the understanding of the behaviour of this type of connection becomes of utmost importance. In order to understand better how old bridges behave, a specific aggressiveness index has been defined, and it enables comparison of the effects of different rolling stocks on the mechanical behaviour of stringers. This index has been determined for different French historical standard trains. For these calculations, a set of real iron stringers has been considered, including different periods of construction, different spans and different inertias. Since fatigue is one of the main phenomena to take into account in order to extend the safe service life of metallic bridges, a fatigue design criterion has been considered. Regarding historical calculation methods, an allowable fatigue stress has been chosen using the Societé Suisse des Ingénieurs et des Architectes fatigue curve, assuming Δσ c = 80 MPa. The method for determining the allowable stress in stringers presented in this paper shows a good agreement with the National Society of French Railways historical inventory of repairs.

Contribution to the study of the influence of the stress ratio on the high cycle fatigue behaviour of riveted joints

“…For this study, as described in Sire and Ragueneau, 56,57 we consider the SIA norm with the linear model corresponding to the detail category Δ σ = 80 MPa and a slope m = 5 up to 1E7 cycles and a constant amplitude fatigue limit (CAFL) from 1E7 cycles. This choice of fatigue curve shows indeed a good agreement with the SNCF railway bridges historical inventory of repairs, for a set of 37 stringers.…”