EVALUATION OF A DESIGN SPECTRUMAT SAINT NICOLA ALLA RENA CHURCH IN CATANIA (ITALY)

摘要

The city of Catania (eastern Sicily) is located in a high seismic area of Italy. The seismic events ofFebruary 1169 and January 1693, with intensity X-XI MCS and estimated magnitude between 7.0 and 7.3,destroyed almost completely the city of Catania. In particular the 1693 earthquake severely damaged theSt Nicola alla Rena Church. The St Nicola alla Rena Church was also damaged by the South EasternSicily earthquake of December 13, 1990 (ML=5.4) and is now under restoration.The geotechnical investigation are spread over an area of 11,200 m2 and reach the maximumdepth of 30 m. Boreholes with SPT and Down Hole (DH) tests as well as seismic tomographyare carried out in order to determine the soil profile and the geotechnical properties of thefoundation soil, with special attention to the variation of shear modulus and damping withdepth. Moreover, Oedometer Tests, Direct Shear Tests, Resonant Column Tests (RCT) andCyclic Loading Torsional Shear Tests (CLTST) have been carried out on undisturbed samples.The shear modulus at small strain is evaluated by in-situ tests (DH) and laboratory tests (RCTand CLTST). Moreover the G-γ and D-γ curves are evaluated by means of laboratory tests.The geotechnical characterization enables the assessment of site effects and earthquake designspectrum for the restoration and strengthening of the St Nicola alla Rena Church. The excitationat the base of the model are synthetic accelerograms related to the 1693 scenario earthquakeconsidering an extended source model. The response of the soil is evaluated in the upper 30 m ofsoil with a 1-D non-linear code.The computed inelastic spectra are compared with those defined by the Eurocode 8 and withthose of the new Italian Ordinance on Seismic Design (O.P.C.M.). This allows the definition of asite dependent design spectrum for the St Nicola alla Rena Church.