New design spectra in eurocode 8 and preliminary application to the seismic risk of thessaloniki, Greece

Abstract

Based on a worldwide database of strong ground motion records in different well constrained site conditions, a new soil classification is proposed for EC8 with the associated amplification factors and the normalized response spectra for 5% damping. Amplification factors and normalized response spectra are also proposed for the current EC8 classification. Then we perform a detailed seismic risk assessment for the city of Thessaloniki using (a) the capacity spectrum method, (b) the Uniform Hazard Spectrum (UHS) for rock conditions compiled applying the SHARE approach, (c) the current and the new site amplification factors to evaluate the site specific demand spectra, (d) the detailed inventory of the Thessaloniki building stock to select the appropriate capacity and fragility curves for each building typology, and (e) available functions to estimate from the physical building damages the causalities and the economic losses. The main conclusions are summarized as following: (a) EC8 site classification, amplification factors and normalized response spectra should be revised. (b) The current methods for the seismic risk assessment are not robust enough; they need serious upgrade in all their components, and yet the uncertainties will remain quite high.