Sorokina G.V.
Sorokina G.V.

Сорокина Галина Вячеславовна Sorokina G.V.


Publications

Statistical Modeling of the Earthquake Input
Issue: №5 2019
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The main problem of modeling statistical seismic vibrations is correct input accelerogram setting. The analysis of the known seismic input models showed the erroneousness of using them in analyzing seismically isolated systems. These statistical models allow one to obtain either reliable accelerations or reliable displacements. However, complicated input models do not quite correspond to real earthquakes. Energy characteristics were not considered at all in the problems of accelerogram statistical modeling. A new model of seismic input, including a random pulse, has been considered. Three parameters has been added to the input model: the magnitude Мw , the epicentral distance R, and the moment when the pulse appears. Varying these parameters within the set limits allows one to adjust additional input characteristics. An example of the proposed process is given.

Calculating Steel Bridge Spans on Earthquake Loads
Issue:
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It is shown that in many cases while calculating bridge spans it is necessary to take into account the soil-structure interaction. If the pier is higher than 5 m, energy dissipation for the main oscillation mode is determined substantially by energy losses, caused by wave propagation in the soil base, thereby the dynamic ratio drops significantly. Furthermore, if a bridge span is shorter than 55 m and the base modulus of deformation Eo < 30 MPa, the force in the piers can be determined by the second mode, for which the superstructure and piers oscillate in antiphase. For bridges with spans over 80 m long at Eo > 30 MPa, seismic forces for spans and piers are determined by the first oscillation mode. 

Some questions of nonlinear seismic isolation behavior
Issue: #3-2022
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An analytical solution of the motion equation of nonlinear seismically isolated systems on the phase plane is obtained. The cases of systems with increasing and decreasing stiffness are considered. A typical example of a system with increasing rigidity is a system with restrictors. Systems with decreasing stiffness include well-known types of seismic isolation with kinematic supports of A.V. Kurzanov and Yu.D. Cherepinsky. For systems of the first type, the motion trajectories on the phase plane are always limited, but with strong displacement restrictions, an increase in accelerations takes place. The proposed solution makes it possible to analyze the dependence of the acceleration growth on the displacement limitation. Solutions of the second type can be unstable, which is clearly seen on the phase trajectories. This requires an analysis of their stability when designing seismic isolation.