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In this paper will be indicated the different behaviour of buildings in Bucharest, mistakes in design and execution, state of codes and regulations in the XXth century, revealing what went wrong. Several national and international research programs were done in the past to understand the causes for the Vrancea seismicity, to study the seismic wave propagation in the region and to assess seismic hazard for Bucharest and other communities. Especially in Bucharest, high-quality seismic data were acquired obtaining a ...

For assuring the stability of important buildings (nuclear power plants) during strong earthquakes, the soil strata under these buildings should not get deformed during the events. In the paper will be analyzed the nonlinear behavior of soil layers during strong earthquakes. As follows from the soil dynamics experiments, shear modulus G and damping D become functions of strain level , and nonlinear behavior could take place. Further, changes could appear in the mechanical properties of the soil layers, expressed b...

The paper presents accelerations, response spectra and spectral ratio for two tower-type buildings, one in Southern part of Bucharest, T1, at ~160 km from the epicenter zone, and other, T2, near the epicenter zone, Vrancea. These seismic characteristics are all from recorded earthquakes triggered in the above mentioned area. 3 triaxial seismic accelerometers were used on 3 levels at each building. The accelerations recorded on the analyzed structures were a result of Vrancea medium magnitude earthquakes between 20...

The technique named "base isolation", resorts to place at the bottom of buildings special components, leading to long fundamental periods that would avoid resonance tendency of buildings with its site in the case of strong earthquakes. The nonlinear characteristics of the isolator layer change the linear period-shift estimation and can lead either to dangerous shortening shift in case of hardening nonlinearity or to unnecessary shift enlargement in case of softening nonlinearity. By neglecting this period-shift di...

Maximum damage due to strong earthquakes occurs at the resonance between the natural periods of the structure and its site, given by the coincidence (or just close to) of the two periods, in which case the dynamic amplifications can damage, even destroy, the structure. From the recordings of (strong) Vrancea earthquakes one can see a dependence of the site natural periods and peak ground accelerations (PGA) on magnitude. For safe avoidance of the resonance it is necessary to define for each site a natural period v...