The allocation to each class is made by GNDT (1986) and instructions developed by CNR (1993).
The index of vulnerability of RC buildings is defined by the following formula (GNDT 1986):
This procedure is based on the application of a hybrid index [I.sub.v], combining information description (typologic and qualitative) and quantitative information, based on the approach followed by the GNDT (Italian Group of defense against earthquakes).
Rather than to follow this approach, which requires working with a large population of building, more sites and seismic intensities, we chosed to adapt, because of lack of data, empirically the original weights of the GNDT method (Tables and 2) to better reflect the architectural differences between buildings in Italian and in the north of Algeria.
Consiglio Nazionale delle Ricerche (CNR), Gruppo Nazionale per la Difesa Dai Terre moti (GNDT), Roma, Italia, 1993.