## 4 Experimental Case Study  
In order to test and verify experimentally the proposed approach, the method has been applied to a real case study: the Navelli town hall located in Central Italy. The building is a reinforced concrete framed structure with three stories and two (about 6.5 m in length) by four (length varying between 3.65 and 7.0 m) bays. Inter-story height is 3.5 m [3; 51].  
The Navelli town hall was affected by the earthquake of 6 April 2009 (Mw = 6.3). Starting from 7 April 2009, ambient noise measurements on the structure were performed  
Figure 17: Structural damage quantification: empirical correlation between the maximum inter-story drift and the maximum curvature difference for the 8-story building.  
and, from the 8 April, a local accelerometric network was installed outside and inside the building.  
Concerning nonstructural elements, significant damage was found both in the external infill panels and in the internal partitions. Infill panels suffered wide cracking at the ground and first stories along both the longitudinal and transversal frames. The most damaged areas were near the stiff stair-structure and along the longitudinal direction. Wide cracks occurred along the longitudinal direction of the infill placed in the last bay of the ground and the first story (Figure 18). Along the transversal direction, lower damage was detected. The damage mechanism was mainly in-plane. Cracking along the diagonals of the panel (due to inclined tension stress mostly concentrated within the center region of the panel) and crushing of panel corners (due to the interaction with the surrounding frame) were observed [52].  
Concerning the structure, some beams showed cracks due to the shear action (Figure 19), particularly those loaded by the one-way slab. As reported in [3], the columns' damage was particularly heavy and extensive at the first level. Possibly, damage on columns was increased by the interaction with the adjacent infill panels [3]. For the same reason, even structural damage on some beam-column joints was found (Figure 19).  
As described in [52], on 8 April 2009, four accelerometric stations were installed for the continuous monitoring of the building. The monitoring system was composed  
Figure 19: Damage on beam–column joints at the first story of the monitored structure (Municipality of Navelli). More details in [3].  
Figure 18: Picture of the monitored structure (Municipality of Navelli): damage of the infill panels. More details in [3].  
by one station installed in each floor (three) on the same vertical along the building height, and one station buried in the ground near the building. Stations were developed by Helmholtz-Centre Potsdam-German Research Centre for Geosciences (GFZ) and the Humboldt University of Berlin [53].  
Particularly, wireless three-directional accelerometers named SOSEWIN were based on MEMS (Micro Electro Mechanical System) with a measurement range of \(\pm\)1.7 g, a bandwidth of 25 Hz and a noise level of 0.5 mg, which were arranged to sample the three components of the ground motion. The digitizer board was characterized by a resolution of 24 bits, effectively providing a resolution of 19 bits. The sample rate, variable between 50 and 400 samples per second (sps), was set up as 100 sps.  
Table 3 shows the information regarding the selected seismic events recorded by these instruments and used in the analysis. Figure 20 shows the map of the recorded seismic events.