M. Zucconi¹, R. Ferlito², and L. Sorrentino³
1)  Department of Engineering, Niccolò Cusano University
Via Don Carlo Gnocchi 3, 00166 Rome (Italy)
e-mail: maria.zucconi@unicusano.it
2)  Seismic and Volcanic Risk Office, Civil Protection Department
Via Vitorchiano 4, 00189 Roma (Italy)
e-mail: rachele.ferlito@protezionecivile.it
3)  Department of Structural and Geotechnical Engineering, Sapienza – University of Rome
Via Antonio Gramsci 53, 00197 Rome (Italy)
e-mail: luigi.sorrentino@uniroma1.it

Keywords: Usability index, Usability probability matrices, Empirical method.

Abstract. In this paper a methodology for assessing the usability of unreinforced masonry buildings, calibrated using the observed data collected after the 2009 L’Aquila, Southern Italy, Earthquake, is tested using data and performances surveyed after the 2002 Molise seismic event.
The methodology is based on the computation of a Usability Index calculated as a weighted sum of seven parameters arranged in categories of decreasing usability. Each parameter represents a structural feature of the construction that may affect the building earthquake response. The Usability Index is correlated with the macroseismic intensity IMCS and Usability Probability Matrices, in terms of fully usable buildings, temporarily or partially unusable buildings, unusable buildings are derived.
The application of the methodology on Molise data is rather successful especially with reference to the prediction of unusable buildings, despite the model was calibrated on a set of buildings belonging to a different region. The limited error can be at least partially explained in light of the differences in macroseismic intensity attribution.