A novel approach to improve the code provision based on a seismic risk index for existing buildings

In seismic risk mitigation policies, synthetic evaluations of the seismic risk of existing buildings can play a significant role in defining the prioritisation of retrofit interventions on different territorial scales. Generally, several seismic risk indices (SRIs) are available and used for this purpose. This study considered a new SRI based on the probability of exceeding a specific performance level requirement. The approach was based on accurate numerical analyses of structural performance assessments within a probabilistic framework. The proposed SRI could be used in practical engineering applications and decision-making processes for single buildings or on a territorial scale (for different building types). Given the enhanced reliability of the proposed approach, it could be considered a useful tool in planning for more effective seismic risk strategies, economic resource distributions, and/or intervention choices in various territorial areas and by different subjects. Further, a comparison between the Italian code index (based on a simplified method) and the proposed SRI is reported and discussed.