Analysis of the seismic event of 24 August 2016 in Amatrice (RI) and its consequences on a r. c. building constructed before 1980

In the two-year period 2016-2017, Central Italy was hit by a sequence of earthquakes of moderately high Moment Magnitude (between M5.5 and M6.5), with epicenters in various locations and each with its own succession of aftershocks that continued for several months. The first event in the sequence, with a magnitude of M6.1, struck the town of Amatrice (Rieti) on the night of August 24, 2016, causing serious losses in terms of human lives and significant damage to buildings. In keeping with typical Italian patterns, the buildings consisted of two main types: historic stone or brick masonry structures, mainly located in the historic center, and more modern masonry or reinforced concrete structures, most of which were built before the 1980s, distributed in the peripheral areas. This paper illustrates the results of structural analyses conducted on two twin reinforced concrete buildings located in Amatrice at Piazza Sagnotti 5,6, which suffered widespread collapse following the event described above. The presence of an accelerometer station operated by the Department of Civil Protection (AMTS) approximately 100 m from the site where the buildings in question were built allowed for a reasonable approximation of the extent and characteristics of the forces that led to the collapse of the buildings. Therefore, the first part of the paper focused on the study of these recordings and allowed the event to be classified as a "near-fault" earthquake. The structural analyses subsequently conducted on the buildings showed, on the one hand, that the behavior recorded under seismic conditions was in line with current knowledge on the subject, and on the other, the severity of the actions experienced during the earthquake of August 24, 2016 and, consequently, the gap in Italian Seismic Code in terms of indications regarding the distance from the seismic source of the expected earthquake, with consequent underestimation of the stresses on the structures hit by the event.