Enhanced Seismic Retrofit of a Reinforced Concrete Building of Architectural Interest

Abstract

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 façades 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 façades and the remaining drift-sensitive non-structural components.

Application of Mode-Adaptive Bidirectional Pushover Analysis to an Irregular Reinforced Concrete Building Retrofitted via Base Isolation

“…Unlike in the case of traditional (non-isolated) earthquake-resistant structures, seismic isolation ensures that the behaviors of building structures are within the elastic range and reduces acceleration in buildings during large earthquakes [2]. Therefore, this technique is applied to not only new buildings, but also existing reinforced concrete and masonry buildings, including historical structures [3][4][5][6][7][8][9][10][11][12][13][14]. The isolation layer consists of isolators and dampers.…”

Influence of the Angle of Seismic Incidence of Long-Period Pulse-like Ground Motion on an Irregular Base-Isolated Building

“…A seismically isolated structure is a structure in which an isolation layer is installed at the foundation level or at an intermediate story level of the building (AIJ, 2016;Charleson and Guisasola, 2017). Seismic isolation has been applied to newly constructed buildings and in the seismic rehabilitation of existing buildings in earthquake-prone countries (e.g., Seki et al, 2000;Kashima et al, 2008;Cardone and Gesualdi, 2014;D'Amato et al, 2019;Terenzi et al, 2020).…”

Influence of the angle of seismic incidence of long-period pulse-like ground motion on an irregular base-isolated building

“…A seismically isolated structure is a structure in which an isolation layer is installed at the foundation level or at an intermediate story level of the building (AIJ, 2016;Charleson and Guisasola, 2017). Seismic isolation has been applied to newly constructed buildings and in the seismic rehabilitation of existing buildings in earthquake-prone countries (e.g., Seki et al, 2000;Kashima et al, 2008;Cardone and Gesualdi, 2014;D'Amato et al, 2019;Terenzi et al, 2020). Installing an isolation layer reduces the risk of structural and nonstructural damage during large earthquakes.…”