Hierarchical policy for seismic intervention of school buildings at urban scale

Seismic risk assessment involves many uncertainties starting from the exposure model and the evaluation of site -specific seismic hazard, and ending with the actual estimation of the expected damages and losses. Seismic risk is also explicitly related to a reliable decision-making process in order to improve pre-and post-earthquake management and resilience. In the case of seismic risk assessment of a large number of critical buildings, like school buildings, at community or regional scale, it is important to establish a reliable and efficient hierarchical policy in order to allow the decision-making regarding the necessary pre-and post-seismic event retrofitting and structural strengthening actions to be undertaken, starting from the identification of the most vulnerable buildings, which need a second order seismic analysis prior to any retrofitting and strengthening action. To this regard, the aim of the present paper is to develop an adequate retrofit optimization framework based on a two -level ranking process for the quick identification of the most vulnerable school buildings, for which a more detailed vulnerability and risk assessment should follow. The herein proposed framework is an efficient and simple tool for prioritization, policy-making and scheduling of seismic prevention projects. The proposed methodology is applied to the school buildings of the municipality of Thessaloniki, Greece. The results of the application indicate that about 3.5% of the total studied school buildings may require further investigation for retrofitting and strengthening.