# Risk and Resilience Assessment of Lisbon's School Buildings Based on Seismic Scenarios
## 5 Risk Indicators and Intervention Prioritization  
### Current Situation  
As referred to in the previous section, based on the return periods that lead to the exceedance of the response limit states, it is possible to compute the expected losses and recovery times associated with annual and 50-year time periods. The expected losses, as a function of the built-up areas (percentages and gross values correspond to red and blue bars, respectively) of school main buildings, are shown in Figure 11. To facilitate the reading of the results, Figure 12 shows the values of the expected losses in 50 years, in terms of the percentage of the school's main building areas, in decreasing order. Figure 11: Expected losses as a function of the built area of the schools. Figure 10: Response spectra associated with seismic scenario 5 (return period of 475 years) for the four ground types. It is possible to verify that four schools register expected losses in 50 years greater than 20% of its area, while in three other schools the expected losses are greater than 10%. These schools are mostly of composite MC or CM typologies. The exception is the school _Luis de Camoes_, which is a reinforced concrete school presenting a structural deficit to withstand the expected seismic action level. It is considered that these seven schools have a high level of expected losses (AEL = 0.7%), a value that is more than three times higher than the value of the general building stock in Lisbon, obtained in previous LNEC studies [60,67], which is 0.2%. Nevertheless, the global annual expected loss of the 28 analyzed schools is also 0.2%, as shown in Figure 11. Thus, the global seismic behavior of schools is in line with the seismic behavior of Lisbon's building stock. This loss value is also close to the one mentioned in the literature for the Italian school buildings portfolio [46], which reflects a greater relative seismic vulnerability of Lisbon's analyzed school buildings portfolio, taking into account that the seismicity of Italy is higher than that of the Lisbon territory. Keeping the current conditions, the expected loss over 50 years is 5.4% of the total area of the schools. Although a loss of 5.4% of the total school building portfolio under analysis cannot be considered negligible, it is not a very large value. This observation is related to the fact that the vast majority of schools have an adequate performance regarding limit states 3 and 4, whose associated losses are potentially substantial. Thus, this loss value is concentrated in a relatively small number of schools. Furthermore, the seismicity expected in Lisbon is moderate, which leads to the fact that the probability of exceeding the most severe limit states is relatively low. The composite building structure schools present a generally less satisfactory performance, as can be seen in Figure 11. The structural system of these schools and the current demands in terms of seismic performance contribute to the fact that the performance objectives are not achieved for most of these schools. It should be recalled, however, that most of them were built before the enforcement of the regulations that consider seismic action in structural design. In what concerns the scenario-based analysis, the calculation of losses associated with each scenario corresponds to the computation of the seismic performance level achieved by each school building for the seismic intensity associated with that scenario. Once determined, the total loss for each scenario corresponds to the sum of losses for each school, given the occurrence of the seismic scenario under analysis. Table 7 shows the expected losses for each seismic scenario. For an earthquake with magnitude 6.6 and a return period of 275 years, the expected loss is approximately 9.1%, while for an earthquake with a magnitude of 7.1 (return period of 2200 years), the expected loss is 17.7% of the total area of the schools.