PSI - Issue 78

Gianrocco Mucedero et al. / Procedia Structural Integrity 78 (2026) 1959–1966

1960

1. Introduction Despite past evidence of the social and economic impacts of seismic downtime, current seismic building design codes focus mostly on ensuring adequate safety during major earthquakes, thus accepting damage to structural and non-structural elements for moderate to severe seismic events. As a result, in addition to direct economic losses due to repair costs, damaged buildings may incur extensive downtime, i.e., “the time necessary to plan, finance, and complete repair facilities damaged by earthquakes or other disasters, which is composed by rational and irrational components” (Comerio 2006). For example, a year after the 2009 L'Aquila Earthquake, just 4% of the 427 structures examined by Liel and Lynch (2012) had their repairs concluded, 29% had repairs in progress, and for the remaining 67% repairs had not initiated. The 2016 Central Italy Earthquake further highlighted the seismic vulnerability of buildings, both from a structural and non-structural point of view (Perrone et al. 2019). The most damaged elements were partition walls, ceiling systems, non-structural vaults, chimneys, and storage racks. More recently, the 2023 Turkey – Syria Earthquake demonstrated that long recovery times are far from being overcome, as many hospitals in the country had to be moved to nearby encampments until repairs of damaged NSEs were completed (Qu et al. 2023). Moreover, almost two years following the event, the majority of the residential buildings that experienced moderate or higher damage remain unrecovered (Mieler et al. 2025). Mitigating these impacts in future earthquakes means that research efforts should focus on empowering individuals to return to their homes while ensuring access to other vital services, such as education, healthcare, and commerce. Moreover, resources are invested more and more in Europe targeting life cycle-based design of new buildings towards a sustainable, low-carbon, and resilient society. Extending the reference time frame up to the entire life cycle of the building implies accounting for additional principles in the conceptual design phase (e.g., use of eco-friendly materials, reduction of the emissions due to transportation, social sustainability, reuse of materials). In particular, aspects related to the reduction of direct and indirect losses (reducing cost and duration of repair activities after a seismic event), re occupancy and functionality after weak to moderate seismic events (avoiding relocation of the inhabitants), to name a few, should be accounted for. In recent years, in addition to life safety, seismic planners and policymakers in the US have highlighted the need to also target functional recovery, by assigning target recovery times (ranging from hours to months) to every newly designed building. According to FEMA P-2090 (2021), such a design target can be defined as the ability of a structure to perform its basic intended use. In the last decade, several frameworks have been proposed to assess the post-earthquake recovery time of buildings and communities. Almufti and Willford (2013) developed the Resilience-based Earthquake Design initiative (REDi), which includes a framework to estimate the downtime of individual buildings and define their recovery state, considering different key metrics, such as repair time of damaged structural and non-structural components, delay time in starting the repairing activities and utility disruption. Cremen et al. (2020) developed an analytical framework to model business recovery times considering multiple types of earthquake-induced downtime (e.g., building recovery and disruption to the wider community, tactics employed by businesses to mitigate these times). More recently, Molina Hutt et al. (2022) proposed a detailed framework to model temporal building recovery trajectories to target recovery states, such as stability, shelter-in-place, re-occupancy, and functional recovery. In the Italian context, the introduction of guidelines for the seismic risk assessment of existing buildings, such as those established by Ministry Decree n.58 28/02/2017 (MIT 2017), commonly known as Sismabonus, marked a significant step forward in the quantification of monetary losses. However, the use of risk metrics is still not explicitly foreseen in seismic design. Moreover, the building functionality recovery, both in terms of cost and downtime, is completely neglected, and no downtime-based design directions are foreseen. Considering the identified gaps, this study investigates the need to incorporate re-occupancy and functional recovery states as future design and retrofitting objectives for Italian reinforced concrete (RC) buildings. 2. Research methodology Two main objectives are pursued in this study: (i) quantify the recovery time of Italian RC buildings designed according to modern seismic guidelines for three recovery states (shelter in place, re-occupancy and functional recovery), across different return periods; (ii) investigate the impact of four retrofitting alternatives on an existing case-study school building in terms of post-earthquake recovery times. The aim is to highlight the need for integrating