Estimation of seismic downtime for building retrofitting decision-making

Recent research demonstrates the need for comprehensive frameworks to achieve an appropriate level of resilience (e.g., energy, seismic) of the European building stock, through integrated retrofitting interventions. Different frameworks have been proposed to identify optimal interventions when several feasible alternatives are available, considering multiple decision variables of different nature, such as social, economic, or technical. Within these efforts and frameworks, less attention has been paid to the post-earthquake recovery time of buildings and communities, thus ignoring the significance of reaching a desired recovery state (e.g., functional recovery) within a specified time frame. To overcome this limitation, this study estimates post-earthquake recovery times and uses them as one of the decision variables in multi-criteria identification of optimal retrofitting of an existing RC building. The case-study building is representative of the Italian school buildings constructed between the 1960s and 1970s and was analysed under two seismic hazard levels (moderate and high). Following the identification of the main structural deficiencies of the as-built structure through nonlinear static analyses, four seismic retrofit measures were selected. Then, the earthquake-induced downtime of each of the four retrofitted building configurations was assessed, analysing the different recovery times as a function of the seismic hazard level and the recovery state. A downtime-based metric, namely the expected annual downtime, was introduced as decision variable within an available multi-criteria decision-making framework to include the impact of downtime, rank the four retrofit measures and identify the preferable one.