E. Zuccolo

A Contribution to the Assessment of the Seismic Vulnerability of Large Structures in Sofia City

An advanced modeling technique that allows us to compute realistic synthetic seismograms was used to create a database of realistic synthetic accelerograms in a set of selected sites in the Sofia urban area. The accelerograms can be used to assess the local site response in terms of the response spectra ratio (RSR). The results of this study, i.e. time histories, response spectra and other ground motion parameters, can be used for various earthquake engineering analyses. Finally, with the help of 3-D finite element modeling, a building’s structural performance is assessed.

Realistic Ground Motion Scenarios: Methodological Approach

The definition of realistic seismic input can be obtained from the computation of a wide set of time histories, corresponding to possible seismotectonic scenarios. The propagation of the waves in the bedrock from the source to the local laterally varying structure is computed with the modal summation technique, while in the laterally heterogeneous structure the finite difference method is used. The definition of shear wave velocities within the soil cover is obtained from the non‐linear inversion of the dispersion curve of group velocities of Rayleigh waves, artificially or naturally generated. Information about the possible focal mechanisms of the sources can be obtained from historical seismicity, based on earthquake catalogues and inversion of isoseismal maps. In addition, morphostructural zonation and pattern recognition of seismogenic nodes is useful to identify areas prone to strong earthquakes, based on the combined analysis of topographic, tectonic, geological maps and satellite photos. We show th...