Probabilistic Seismic Risk Assessment of School Buildings

The inadequate behavior of existing school buildings observed during past earthquakes in Italy have underlined the need to accurately understand their seismic performance. In order to do so, different metrics can be adopted to characterize their seismic response, either more focused on structural aspects or economic variables. This paper assesses the seismic risk level for three case study school buildings, representing the main typologies found within the Italian school building stock, and comments on the eventual need for retrofitting. A probabilistic-based earthquake engineering (PBEE) performance assessment is carried out using detailed numerical models, analyzed under ground motion records of increasing intensity, to quantify risk-based decision variables, such as expected annual loss and mean annual frequency of collapse. As an alternative to the detailed PBEE framework, a simplified seismic risk classification framework, recently applied in Italy, was also implemented. Different uncertainty parameters are included in the risk estimation frameworks, with a view also to future large-scale implementation of cost-benefit analyses. Lastly, one of the school buildings is further analyzed to understand the impact of the structural modelling uncertainty in the risk estimates and the consequent need for its proper consideration. The results show how the simplified risk classification framework is, as expected, conservative with respect to the detailed component-based approach, as well as the need for retrofitting of some of the building structural systems.