A CRITICAL REVIEW OF FRAGILITY CURVES FOR EXISTING RC BUILDINGS

In recent years, many studies were been carried out in order to understanding and later mitigate the seismic risk. Several important projects have been funded, different methodologies have been developed; in particular, for emergencies management several application have been carried out with good results. On the contrary, mitigation and prevention of seismic risk could be more efficient by setting a careful assessment, maintenance and retrofitting of the built. In this sense, it to be noted that the seismic capacities of existing RC buildings have shown a key role in recent seismic events (e.g. Southern Italy 1980, Turkey 1999, L’Aquila 2009, Lorca, 2011, Emilia plan 2012). In particular, old RC buildings have often shown a poor and brittle behavior. Moreover, the low seismic performances of these buildings are the main reason of significant earthquake losses (in terms of economic, social and political activities) that can been considered generally as a direct consequence of physical damages on the buildings. About these important topics, it is the opinion of the authors, that quantitative models of fragility, referring to the most common types of buildings, have a key role in the evaluation process of risk and should been continuously improved. Therefore, in the seismic risk studies, a fundamental step is the development and use of fragility curves representative of the behavior of existing RC buildings. A significant number of proposals are currently available in the scientific literature. In this study, a critical review of existing different procedures for RC with Moment Resisting Frames (MRF) has carried out in order to highlight advantages and weakness of each proposal. A great variability in terms of geometrical, mechanical and structural characterization, structural modeling, method of analysis, scale of damage, parameters of seismic intensity and statistical procedure has been highlighted, and finally an optimal procedure of fragility analysis has been outline