Selection of optimal seismic retrofitting for existing school buildings through multi-criteria decision making

The poor performance of school buildings in Italy during past seismic events has underlined their high vulnerability to earthquakes. To improve their seismic performance, retrofitting interventions are commonly designed and then evaluated against a range of key decision criteria. However, more than one intervention may be found to reduce the seismic risk of the structure but it may not be clear which scheme is the most effective given the diverse evaluation criteria. In such cases, multi-criteria decision-making procedures are practical tools that can help to solve this issue, especially when multiple evaluation parameters are considered. This study conducts a full seismic assessment of two existing RC school buildings located in different regions of Italy. For both buildings, similar retrofitting interventions are proposed and designed according to the requirements specified by the Italian building code, NTC 2018. The retrofitting interventions are assessed through non-linear dynamic analyses to thoroughly estimate their overall performance and expected losses. The retrofitting interventions are then comparatively evaluated considering parameters that integrate economic, social, environmental and technical aspects that have a significant role in the decision-making process. The preferential rankings of the retrofit alternatives obtained for both buildings are used to identify the optimal retrofitting solutions for each case and are compared to determine what parameters influence such optimal solutions according to the different buildings' characteristics. The outcomes of this study can assist engineers, or general decision-makers, throughout the evaluation and subsequent selection of retrofit options for existing school buildings.