13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- Fig.5. Chapel XVII. View of the Monitored Areas. Left Side: Sensors 5, 6, and the Frescos Detachment. Right Side: Sensors 1-4 and the Vertical Crack. Fig.6. AE Acquisition System. The Acoustic Emission acquisition system is shown schematically in Fig.6. The piezoelectric transducers (PZT) are calibrated over a range of frequency between 50 kHz and 800 kHz. The USAM acquisition system consists of 6 pre-amplified sensors, 6 units of data storage provided of triggers, a central unit for the synchronization operations, internal clock and a trigger threshold. The obtained data are: progressive number of each signal, acquisition time, intensity, duration, number of oscillations over the threshold value [2,3]. 4. AE and seismic events Non-destructive testing methods are currently used to evaluate structural damage phenomena and to predict their development over time. In particular, the evaluation of damage in historic buildings is often a complex task [4,5]. It is essential to distinguish between stable damage patterns and damage in evolution toward a catastrophic collapse. Some structural damage can be triggered by
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