Cristian Arion

Seismic Risk Assessment of Romania

This paper summarizes the UTCB results for the “National Risk Assessment—RO RISK” project. Within the RO-RISK project, coordinated by the General Inspectorate for Emergency Situations, the first nation-wide assessment of all types of natural risks was performed in 2016. The work was supported by collaboration of disaster reduction experts and earthquake risk modelling specialists from INFP and URBAN-INCERC. The seismic risk assessment was performed for the entire country, at the most detailed resolution available, which is the administrative-territorial unit. For each building typology, four limit states were considered in order to generate fragility curves. Each limit state is associated with a loss percentage, in order to generate vulnerability curves. The assessment shows that among the 10 analysed hazards, the seismic hazard produces the largest impact at country level, 75% of the population and 45% of the vital networks are exposed to moderate and high earthquake risk and Romania’s capital Bucharest, is highly exposed to earthquakes.

Ground Types for Seismic Design in Romania

The paper presents an overview of available data concerning ground types for seismic design in Romania. A short overview of a ground information database created during BIGSEES Romanian project is presented. A comparison of shear wave velocity for 19 sites in Bucharest determined by PS logging measurements and by Wald topographic slope method is discussed. The paper reiterates the conclusion of a study regarding the Eurocode soil factor S derived from the Romanian seismic motions. The need for an enlarged database of in situ determined ground condition is underlined, at least at the location of seismic stations. Based on borehole-specific data (geotechnical properties, hydrologic factors) and velocity profiles, evaluations of soil liquefaction potential and related indices were performed by using empirical equations proposed in literature. The application of GIS tools provided a spatial distribution of liquefaction susceptibility of Quaternary alluvial sediments in Bucharest.

Prediction of Site Characterization Based on Field Investigations and Empirical Correlations

Significant damages of built environment recorded during past seismic events, closely linked to notable human and financial losses, have led to consideration of Romania’s capital city as one of the major earthquake-prone urban area worldwide. Strong historical ground shaking and extensive distribution of seismic networks have outlined that variability and specific parameters of layered unconsolidated sedimentary young deposits represents one of key component in site-response analysis. To predict seismic effects of near-surface soils, comprehensive surveys are needed for a realistic estimation of dynamic behaviour and site characterization. A large number of shallow and deep boreholes, standard penetration tests and non-invasive field techniques as down-hole and SASW measurements have been carried out in Bucharest sites. All the tests reported in the paper were performed at CNRRS (National Center for Seismic Risk Reduction) (now, Seismic Risk Assessment Research Center https://ccers.utcb.ro) and UTCB (Technical University of Civil Engineering of Bucharest). Shear wave velocities and penetration resistance have been set as main indicators in quantifying seismic properties. Empirical correlations to predict VS from N-SPT test values were developed by using statistical methods. A comparative method between soil dynamic indexes determined by in situ investigation and the ones predicted using empirical models have been performed. The end-results can be considered as guidelines to predict the potential effect of site conditions on similar soil types, layer sequences and properties.

Expected Direct Seismic Losses Assessment Using Gis. Case Study for Iaşi Municipality

Abstract Expected direct seismic losses assessment is performed on probabilistic basis using world-wide accepted methodologies for two study areas located in Iasi Municipality. The probabilistic assessment refers to the following issues: site-dependent seismic hazard, expected seismic response of buildings, seismic fragility of structures, expected seismic damage. The analysis of the spatial distribution of the existing building stock as well as the presentation of the results on expected direct seismic losses are performed using geographic information systems (GIS)