Historical load effects on fatigue of metallic railway bridges

Abstract

This paper presents load models for quantifying the effect of historical rail traffic on the remaining fatigue life of riveted bridges in the UK. Three types of load models, based on realistic trains, accounting for differences in rail traffic composition, are developed and subsequently used for investigating their effect on the accumulation of fatigue damage in typical old metallic bridge structures. The overall findings show that the increase within train axle loads from 1900 to 2010 is the main attributor to the significant increase in fatigue damage caused from the modern trains compared to the residual fatigue damage from the historic trains. These findings are particularly relevant to the majority of existing metallic rail bridges on the rail network, which are known to have a span length less than 10 m. These findings show the importance of considering the effects of historical loading for more reliable fatigue assessment purposes, leading towards more efficient planning of bridge maintenance and renewal programmes

Discussion: Historical load effects on fatigue of metallic railway bridges

“…According to Equation 1 in the original article (Imam and Salter, 2018), the authors quote the dynamic factor (Daf) for fatigue as 3:…”

Influence of material anisotropy on fatigue crack growth in C–Mn steels of existing structures

“…Examples are cover plates in riveted joints of existing bridges, where multiple operations such as cutting and drilling were applied, and the microstructural orientation was not checked before it was applied in the structure. Riveted joints in bridges are prone to fatigue failure 6 …”

Evolution of load conditions in the Norwegian railway network and imprecision of historic railway load data

“…As the fatigue damage mechanism is highly sensitive to the magnitude of the stress range, assuming today's traffic over the history of the structure will yield grossly conservative results (Imam, Righiniotis, & Chryssanthopoulos, 2008). Ignoring historic loads can, on the other hand, overestimate the remaining service life, as such loads may have contributed significantly to the fatigue damage of certain details, as shown by Pipinato, Pellegrino, and Modena (2012b) and more recently by Imam and Salter (2017).…”

“…Each train has a particular locomotive with various geometries and axle loads; the passenger and freight wagons vary in axle loads, while the wagon geometry is unchanged throughout the entire period 1900-1970. The load model is extended in Imam and Salter (2017) to lines with only passenger trains or only freight trains, with the study also including a description of geometry ranges of locomotives, freight wagons and passenger wagons of the rolling stock prior to 1970.…”