DOI: 10.4018/IJGEE.2018010101 International Journal of Geotechnical Earthquake Engineering Volume 9 • Issue 1 • January-June 2018 Copyright © 2018, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. 1 Free-Field Seismic Response Analysis: The Piazza dei Miracoli in Pisa Case Study Andrea Angina, Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy Andrea Steri, Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy Stefano Stacul, Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy Diego Lo Presti, Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy ABSTRACT This paper shows the results of free-field seismic response analyses (SRA), that were performed for the subsoil conditions of Piazza dei Miracoli in Pisa. The site investigation and in particular the shear wave velocity profile is extended down to 120 m below the ground level. One-dimensional SRA were carried out by using three computer codes, EERA, STRATA and ONDA. The first two codes perform the analyses in the frequency domain considering a linear-equivalent soil model. ONDA analyses the problem in the time domain assuming a true non-linear soil behaviour. In particular, the Ramberg-Osgood constitutive model, coupled with a modified Masing criterion was assumed. The computed elastic response spectra were compared to those prescribed by the Italian Building Code, which represents the Italian implementation of Eurocodes. Some details concerning the response spectra prescribed by Italian Building Code are also given. KEywoRdS Non-Linear Soil Behaviour, Piazza dei Miracoli in Pisa, Leaning Tower, Seismic Response Analysis, Site Effects INTRodUCTIoN The stabilisation works of the Leaning Tower of Pisa ended in 2001 (Jamiolkowski, 2001; Burland et al., 2000, 2003). The Tower was re-opened to visitors, after a closing period long at least one decade. After re-opening, works related with the material restoration of the Tower, some recovery activities for the monuments located in Piazza dei Miracoli and the monitoring of the Tower displacements were carried out (Burland et al., 2009; Squeglia & Bentivoglio, 2015). More recently, after the seismic events that hit the regions of Central Italy, especially the Emilia Romagna earthquake in 2012 (Lo Presti et al., 2013; Fioravante et al., 2013), the interest about the seismic response of the Leaning Tower has become relevant for the Italian geotechnical community. It is well known that the analysis of the complex dynamic soil-foundation-superstructure interaction can be simplified studying separately (Kramer, 1996): 1. The free-field response; 2. The kinematic interaction; 3. The inertial interaction.