Isolamento sismico a grande scala per la salvaguardia del tessuto urbano nella ricostruzione post-sisma

After a seismic event, the observation of the consequences to buildings and infrastructures always highlights extensive damage in ancient or historical district of the hit towns. Damage depends not only on the local amplification of the seismic action, but also on the quality of the materials and the construction technique. The negative consequences of traditional design and construction approaches appeared in all their negative evidence in all areas of Central Italy affected by recent seismic sequences of medium intensity (M5-M6) in 2016-17. Now the reconstruction should solve the problem to rebuild with safety but preserving the historical aspect of buildings and landscape. This paper proposes a particular application of the known technique of seismic isolation for the integral seismic protection of entire urban quarter or entire small centers characterized by building of different characteristics also significantly irregular. The adoption of seismic isolation systems at village or quarter scale involves the construction of large floating slabs, supported by seismic isolators and/or dampers, above which to construct buildings that can present the aesthetic and constructive characteristics of the collapsed traditional ones. These large slabs could have the size of entire compartments (hundreds of meters on each side). Solution of ground isolation have already been implemented in various countries to isolate complex of buildings. The solution allows a correct interpretation of the objective to rebuild "as it was, there where it was", safeguarding the landscape, prolonging the lifetime, and saving the expected cost. The paper illustrates a case study related to a quarter of a historic town in central Italy and shows the constructive solutions.