Assessment of existing steel railway bridges, Algeria

Steel railway bridges represent more than 30% of the total railway bridges existing in Algeria. Many of these bridges were built during the second half of the 19th century and the beginning of the 20th century. The majority of them have been constructed since the creation of the railway lines. To ensure the safety of the bridges, The Algerian railway company SNTF has launched a survey to inventory the eventual damages encountered and evaluate the bearing capacity of the bridge structures. The recalculation of those structures, based upon design rules, revealed that capacities of different elements in the bridge decks were seriously exceeded. As a consequence, the majority of the bridges were classified deficient, therefore requiring immediate replacement decks bridges. However, until now, the whole bridges remain operational without any incident being reported. To avoid unnecessary replacements, which have a significant financial impact on the country's economy, the aim of this work is to show that methods based on a semi-probabilistic approach cannot be considered as a good tool for existing structure evaluation.