Seismically isolated building response under far fault 2016 earthquake in central Italy

After L’Aquila 2009 earthquake (Central Italy), many new and retrofitted buildings with base isolation have been realized in the area. Collapsed buildings, or heavily damaged buildings, were demolished and reconstructed with base isolation. The isolation systems were generally composed by both rubber high damping isolators, and plane friction isolators (sliding), and, in some buildings, by single and double pendulum sliding devices. Some buildings, with minor structural damage were retrofitted also with isolation systems, both with rubber high damping isolators, and plane friction isolators, and also by double pendulum sliding isolators. All these isolated buildings were interested by the strong seismic events in Central Italy. The seismic sequence during years 2016 and 2017 involved a great area In Central Italy, interesting four regions and more than 100.000 buildings. Several main shock events occurred, namely Amatrice earthquake (Mw 6.0 on August 24th, 2016), Valnerina earthquakes (Mw 5.9 and 5.4 on October 26th,2016), Norcia earthquake (Mw 6.5 on October 30th, 2016), and Montereale – Capitignano earthquakes (Mw5.0, 5.5 on January 18th, 2017). The seismically isolated buildings in L'Aquila area were involved by the seismic sequence. Several different dynamic and seismic behaviour were observed in those buildings, depending upon isolation system (noticeable differences have been observed between curved sliding isolators and rubber high damping isolators) and upon soil – structure interaction. Significant displacement has been observed caused by soft soil, and inverse velocity seismic soil profile. In the work several buildings are examined, analysing the seismic behaviour both in the 2009 earthquake (without seismic isolation) and during 2016 – 2017 seismic events (retrofitted by seismic isolation). Differences in the seismic behaviour do not depend by the isolation system.