Enhanced Seismic Retrofit of a Reinforced Concrete Building of Architectural Interest

Modern heritage buildings designed in the 1950s and 1960s often feature poor seismic performance capacities and may require significant retrofit interventions. A representative case study in Florence, i.e., the edifice housing the Automobile Club Headquarters, is examined here. The building was designed in 1959 with an articulated reinforced concrete structure and presents some enterprising solutions for the time, including suspended floors accommodating large glazed curtain wall fa\ue7ades in the main halls. The original design documentation was collected with accurate record research and checked with detailed on-site surveys. Based on the information gained on the structural system by this preliminary investigation, a time-history assessment analysis was carried out. Remarkable strength deficiencies in most members and severe pounding conditions between the two constituting wings, which are separated by a narrow technical gap, were found. As a result, a base isolation retrofit hypothesis is proposed in order to improve the seismic response capacities of the building without altering its elegant architectural appearance, being characterized by large free internal spaces and well-balanced proportions of the main structural members. A substantial performance improvement is obtained thanks to this rehabilitation strategy, as assessed by the achievement of non-pounding response conditions and safe stress states for all members up to the maximum considered normative earthquake level. Furthermore, the very low peak inter-storey drifts evaluated in retrofitted conditions help in preventing damage to the glazed fa\ue7ades and the remaining drift-sensitive non-structural components

Ground penetrating radar survey for structural assessment of a heritage sport building

In order to prevent seismic damage on building heritage built before Seismic Standards, constructions require to be assess to verify the structural response in the case of multi-level intensity seismic actions. This problem especially concerns those buildings with a social function as schools, hospitals, etc., or with historical and architectural value as that designed by important builders of the past. This is the case of the bar-restaurant building of "Bellariva" Sport Centre, designed and built in Florence by the World-famous Italian engineer Pier Luigi Nervi in the Sixty years. Its structure is characterized by reinforced concrete frames and hosts the locker rooms of the swimming pool and a bar on the first floor, a restaurant on the second, where a long crack was observed. The presence of a large balcony with heavy perimeter planters near the cracked zone motivated the execution of on-site tests finalized to determine the steel bars connecting the restaurant floor to the balcony. A Ground Penetrating Radar survey was performed in order to determine the internal structure of the floor, dimensions and disposition of steel bars, and to gather information about the connections between perimeter beams and balcony at the level of the restaurant. The experimental campaign allowed to refine a computational Finite Element Model that was utilized for the performance analysis of the structure in the current state. The paper presents the main results of a preliminary seismic analysis carried out on the structure, on the basis of which some retrofit intervention are suggested