GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 2.3 457 CLARA - Smart Cities project: ambient vibration survey on strategic buildings in Matera (Italy) G. Massolino 1,2 , D. Sandron 1 , M.R. Gallipoli 3 , A. Rebez 1 , M. Mucciarelli 1,4 , T.A. Stabile 3 1 OGS – National Institute of Oceanography and Experimental Geophysics, Trieste, Italy 2 Polytechnic Department of Engineering and Architecture, University of Udine, Italy 3 CNR – IMAA , Tito Scalo (PZ), Italy 4 Di.S.G.G. – University of Basilicata, Potenza, Italy Introduction. In October 2015 a survey campaign was performed in Matera (Italy) in the frame of the CLARA Smart City project (Cloud plAtform and smart underground imaging for natural Risk Assessment). Among the objectives of the project there was the aim of non- invasive methods for buildings and infrastructures diagnosis. In this context, 11 building to be tested were identified in Matera, 6 of which had been tested with ambient vibration techniques during a 3 day survey: 94 passive single station measurements have been performed. The main aim was the identification of the main vibrational modes of the structures. Methods. Tri-axial tromographs TROMINO® (Moho SRL) have been use for ambient vibrations recordings. Data have been analyzed with Grilla software. Outside each building an HVSR (Horizontal to Vertical Spectral Ratio) free-field test has been performed, in order to characterize the seismic response of the foundation soil (Di Giulio et al. , 2005; Parolai et al. , 2005; Castro et al. , 1998). The sampling frequency has been set to 128Hz and the recording time to 30 minutes; triangular smoothing has been set to 10%. The buildings have been tested with synchronous ambient noise recordings and with different acquisition configurations, to estimate more accurately the main vibrational modes. Testing configuration were usually along a vertical line, with a measure acquired at each floor, and along an horizontal lines, with acquisition at different points of the same floor. The measure at the basement has been taken as a reference for all the measures. Recording time has been set to 12 minutes for each measure and triangular smoothing has been set to 3%. Data have been processed through HVSR and SSR techniques in order to better assess translational and torsional modes (Gallipoli et al. , 2004). The map in Fig. 1 report the buildings monitored. Fig. 1 – Map of the distribution of the identified buildings in Matera to be tested (red symbol) and already tested (green symbol).