GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 2.2 413 THE SEISMIC VULNERABILITY ASSESSMENT OF THE MEF BUILDING IN ROME DOWNTOWN: THE CONTRIBUTION OF THE 1D SITE RESPONSE ANALYSIS L. Macerola, M. Tallini, G. Bosco Department of Civil, Construction-Architectural and Environmental Engineering, L’Aquila University, Italy The results of the 1D local seismic response analysis of the area of the Italian Ministry of Economy and Finance building (in the following MEF site) are presented. The seismic site analysis has been planned to support the seismic vulnerability assessment of the above- mentioned building placed in the Rome downtown (Castro Pretorio district nearby Porta Pia and Termini railway station). The subsoil model and the seismostratigraphy at the MEF building site have been achieved via an extensive investigation program that included the drilling of a 60 m-deep borehole with continuous sampling (named S1), the retrieval of 21 undisturbed and disturbed soil samples on which were carried out several static and dynamic lab tests as well as the determination of the physical properties of the different soil layers. Once coring was completed the borehole was equipped with the PVC pipe for later down- hole tests. The geophysical investigation comprised the execution of two down-hole tests in the borehole S1, using two different techniques (single receiver and couple of receivers 1 m apart), the execution of another down-hole test (couple of receivers 1 m apart) inside a different borehole, always located in the MEF site, the execution of MASW and seismic refraction investigation and the recording of three long-duration microtremor measurements throughout a 24 hours time interval. Based on the results of the intensive investigation and by interpreting the litho- stratigraphy of the borehole S1 considering the geological background and mapping of the Roman area (APAT, 2008; AA.VV. , 2008), a multitask approach was carried out to define a representative subsoil model of the MEF site, to assign the numerical values to the parameters involved in the modelling, to select the input motions, and, finally, to perform the 1D numerical modelling with the code STRATA (Kottke and Rathje, 2008) (Tab. 1; Figs. 1, 2, and 3). Based on the geotechnical and down-hole data, a seismostratigraphy of the MEF site comprising several horizons showing different Vs values was reconstructed to a depth of 60 m bgl (Tab. 1).Theseismicbedrockwasestablished at 550 m bgl considering the stratigraphy of the nearby Circo Massimo deep borehole (AA.VV. , 2008; Pagliaroli et al. , 2011) which evidences at that depth, within the between the Pliocene Fig. 1 - Vs values from the down-hole tests performed in the borehole S1. The acronyms TLL, SKF, CIL and MVA refer to the geological formation of the CARG sheet 374 Rome at 1:50,000 scale. Vs: shear wave velocity value; Z: depth (m bgl).