Seismic vulnerability of reinforced concrete constructions in northern Morocco

The concept of earth quake vulnerability is used in this work to predict the average damage that buildings are likely to experience on a large scale with the occurrence of an earthquake of given intensity. The use of the vulnerability concept is considered in the context of the particular typology of reinforced concrete buildings, which are commonly encountered in northern Morocco and which have not been engineered with adequate earthquake protection. The vulnerability scale is adapted based on the Italian method called "Gruppo Nazionale per la Difesa dai Terremoti" (GNDT) by adjusting the weighting coefficients to better match the local architectural characteristics of these types of buildings. A correlation is then proposed between the damage index considered as the main tracked effect and the causes that are herein idealized through the vulnerability concept. The results of field observations performed after the strong earthquake in Al Hoceima of magnitude 6.3 that hit the region of northern Morocco in 2004 have shown that the proposed method can correctly evaluate vulnerability. Relative fragility curves for this building typology are finally depicted.