Realistic analysis for remaining fatigue life for historic riveted railway bridges

Given the lack of historic information regarding traffic conditions and structural details of railway riveted bridges more than 100 years old, most assessments relate to the structure's current condition. Moreover, fatigue assessment procedures are also usually associated with loading models taken from current Codes and Standards that may not represent the bridge's real load history, hence leading to unrealistic remaining fatigue life predictions. This paper proposes a novel approach to assess the remaining fatigue life of historic railway riveted bridges common in the Chilean railway bridge portfolio by introducing three novel elements. First, it considers a typological approach by classifying bridges by their construction details and retrofitting. Secondly, the bridge archetype is analysed in different configurations representing typical historic bridge strengthening sequences. Third, the loading spectrum is defined using real data on train types and freight transited through the Chilean railway network through the ages. Comparison of the results with the ones obtained using loading models prescribed by different standards (EFE, Eurocode and AREMA), shows that the latter tend to overestimate the fatigue damage of the bridge. Finally, reliability analysis methods are employed to determine the probability of failure of the bridge most fatigued connection, and this is compared to the one obtained by applying Miner’s rule. The reliability analysis shows that the failure probability is within acceptable values for all bridge configurations, and that Miner’s rule leads to conservative results when compared to a wide range of reliability indexes, proposed in current literature.