Soglie di priorità per l'adeguamento sismico di edifici scolastici costruiti o ristrutturati prima dell'entrata in vigore delle NTC 2008

In the present paper some priority thresholds for the seismic strengthening of school buildings are proposed in arder to allow for a progressive reduction of the vulnerability of existing buildings. Among years, the seismic codes were improved and modified according to the new knowledge acquired through the research. Consequently buildings designed as earthquake-resistant, may have security levels lower than those currently required. The defined priority thresholds allow placing each structure in a different class that represents the vulnerability level, so to obtain a prioritization ranking for the interventions. The study is part of a research project supported by the Friuli Venezia Giulia Region for studying the vulnerability of the regional school buildings. An extensive documentary research on structural projects of these buildings al­ lowed to define the reference thresholds, in order to establish the parameters of comparison among buildings designed according to current seismic codes and those designed according to the standards in force at the time they were constructed. Then, every building, even those designed without considering seismic actions, with a preliminary assessment of the seismic capacity, can be placed Within the hierarchy of the priorities for the strengthening intervention.