Analysis and seismic isolation of an older reinforced concrete vaulted building

Reinforced concrete (R/C) structures designed with earlier Technical Standards often require retrofit interventions to improve their performance capacities, especially against seismic actions. A case study belonging to this class, i.e. the swimming pool building of the Naval Academy in Leghorn, Italy, rebuilt in 1948 after being destroyed by air raids during the Second World War, is examined herein. The structure of the main hall is constituted by a prefab R/C vaulted roof designed by the world-famous Italian engineer Pier Luigi Nervi, supported by a set of inclined columns with relatively small sections. The assessment analysis in current conditions shows unsafe response conditions of these members, as well as of several other columns and beams, under seismic action scaled at the basic design earthquake level. In order to minimize the impact of the retrofit intervention on the exposed structural elements, a base isolation solution is proposed for the building. The verification analyses in protected conditions highlight a substantial enhancement of the seismic response capacities of the structure, with no intervention required in the elevation structure, up to the maximum considered normative earthquake level.