Rina Consulting, between 2019 and 2021 was involved in the seismic vulnerability assessment and retrofit design of a large public buildings stock in Italy. The project includes several buildings built between the 40's and the 90's located in regions prone to very high seismic hazard and characterized by strategic uses.

The buildings included in the portfolio span from masonry structures to reinforced concrete structures, including precast buildings. All the structures were submitted to linear and nonlinear analysis to define their seismic vulnerability and identify their structural deficiencies; then a retrofit design was performed to guarantee the increase of the building's seismic capacity according to the requirements of National code. Alternative retrofitting scenarios were investigated, and compared by means of cost-benefit analysis, with the aim to guarantee a good balance between the costs and the structural efficiency of the interventions.

The main aim of the paper is to present practical considerations regarding the main issues related to the data gathering, the seismic input definition and the seismic vulnerability index obtained for the different building typology. The study aims also to investigate the comparison between the seismic requirements assumed for the original design and the seismic requirements assumed for the seismic vulnerability according to the current national code and its influence on retrofit interventions costs. The collected data form part of a database which scope is to provide a criterion for predicting retrofit strategy and costs as a function of the seismic vulnerability index. Final purpose of the study is to provide possible improvement of the methodologies to be applied to similar projects that include large building stock in order to define a possible efficient framework to be proposed to the different stakeholders.