Use of fragility curves in emergency management and seismic risk mitigation

Strong European earthquakes have showed that RC buildings structural performance have always a crucial role in terms of earthquake losses and urban resilience. Due to importance of the topic, a considerable number of studies have been carried out in the past. Nevertheless, the complexity of the problem requires still further enhancements in order to define effective tools to prevention and mitigation of the seismic risk. Generally, a new proposed method should be capable on the one hand to ensure a sufficiently reliability and not too costly in the preparation of seismic scenarios, on the other hand to ensure a realistic prevision of structural performance of the studied buildings to define accurate retrofitting policies in large scale. A efficient method to define Damage Levels (DL) is a mechanics-based approach, in which structural deformations or section yield demands that correspond to physical damage are derived. Thus, the main step is the correct definition of relationship between DL and damage status defined trough numerical analyses. This aim plays a fundamental role in assessment of seismic capacity of existing constructions, in post earthquake emergency management and in experimental activity (in laboratory or numerical). About this important topic, it is the author's opinion that quantitative damage states should be defined based on objective of real using of Fragility Curves (FCs). In other words, FCs specifically defined for the emergency management should be different from those using in seismic risk mitigation policies. It is important define others parameters to better investigate about global damage state. The number and type of structural elements for which a fixed limit state has been exceeded is needed to define a correct performance level. FCs will be defined considering an economic point of view which involves that the higher level of loss must be adequately captured. Alternative performance definition will be proposed and discussed to establish risk and cost related.