Seismic Assessment of the Milan Central Railway Station

In this paper, a study of the Milan central railway station structure is presented, aimed to assess the seismic vulnerability of this monumental building. The opportunity has been offered by the need of internal restoration aimed at the construction of a huge shopping centre. The overall internal restyling and structural restoration is quoted 105 millions of Euros. Based on the preliminary design of Ulisse Stacchini dated 1912, the central railway station of Milan was completed in 1931. At that time, the station was among the wider railway stations of Europe. The quantities of employed materials are really impressive: 43000 tons of cement were cast for the main structures and 2500 tons of steel were employed for galleries and roof arches. The station is composed of a main building and a train gallery. The main building structure is constituted by R/C frames that are quite unusual for geometry and conception. The concrete roof floor is hung to steel truss arches with 40 m span. The external walls are covered by decorative concrete elements with 20-40 cm of thickness and marble. The train gallery is formed by a steel truss arches system completed by glass panels. While the steel works are fully documented by design drawings and photographs, information concerning the R/C structures is not available; therefore to define the main structure schematics and the material properties a wide investigation was necessary. The city of Milan is situated on a very low level seismic region. For this area, a PGA of 0.07 is accounted with a return period of 1000 years. Due to the very small amount of steel content within the concrete columns and beams, a structural factor of 1.5 is assumed. The seismic analysis shows that the overall safety level of the station is acceptable, although some local structural deficiencies need to be faced by means of a proper strengthening design.