Identification of parametric non-physical linear systems to reproduce seismic induced response

The paper discusses the potential and reliability of identified parametric non-physical linear systems with increasing model order in closely reproducing the experimental seismic response of a complex monumental structure. The measured vibration data have been extracted from a multi-sensor system, installed for the long-term structural monitoring of an historical monumental church, the Basilica S. Maria di Collemaggio, which was heavily damaged in the 2009 L'Aquila earthquake. The monitoring system has been used as test bed due to the specific features of the wireless sensor networks, purposely designed to detect earthquake-induced vibrations. Both frequency and time domain methods have been employed for the data processing and interpretation. The subspace state-space system identification (4SID) has been used to identify a class of parametric non-physical linear systems, which are able to reproduce the measured seismic response and are successively discussed for their effectiveness in the mechanical interpretation of the structural behavior.