Structural assessment of an historical steel railway bridge in the north of Spain

At the beginning of the 20th century, some railway lines were built in the north of Spain to support industrialization in this area. In the region there were coal and iron mines, as well as ports to market the products, reason why it was one of the first Spanish regions to develop. Due to the rugged relief, it was necessary to adapt the layout of the lines to the terrain, so many bridges were built for that purpose. At the same time, steelmaking was transitioning from manual to industrial metallurgical furnaces and processes. These processes determined the structural and durability characteristics of the metallic material used for those bridges. Nowadays, the maintenance of this type of bridges is conditioned by the difficulty of access to inspect, the structural typology of the details, and the mechanical characteristics of the material; and also the insufficient training of the technicians who inspect this type of structures. The case study is an old steel bridge that served the trade of an important regional factory. Routine inspections found no major structural defects; however, thanks to a complete historical and structural study that was being developed, significant damage was detected that made it necessary to immediately stop traffic on the bridge.