EVALUATION OF EC8 SITE-DEPENDENT ACCELERATION RESPONSE SPECTRA USING STRONG-MOTION ITALIAN RECORDS





1 INTRODUCTION
The Eurocode 8 (EC8) building code (CEN, 2004) recommends the use of two design horizontal acceleration spectra, i.e. the Type 2 spectrum for regions where maximum magnitudes are not expected to exceed 5.5-6.0 (low to moderate seismicity) and the Type 1 spectrum for regions where maximum magnitudes are expected to exceed 5.5-6.0 (high seismicity). For both seismicity levels, different site-dependent spectral shapes are assigned, according to the EC8 classification system, for five subsoil categories (A, B, C, D and E) defined in terms of stratigraphic conditions and representative geotechnical parameters. Conversely, the design vertical acceleration spectral shape is unique, independently on magnitude and ground conditions. Earlier version of EC8 provisions is based on the work by the SC8 Project Team 1 (1999) whereas spectral shapes adopted by EC8 are mainly based on the background study of Rey et al. (2002). The dataset used by Rey and co-authors is derived from the European Strong Motion Database (Ambraseys et al., 2000) and it includes records from all over Europe (e.g. Greece, Italy) and adjacent countries (e.g., Turkey) with different seismotectonic environments and different fault mechanisms (normal, thrust, strike-slip, etc.). Therefore, it is of practical interest to see whether the EC8 spectra are in agreement with those that are


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