Theoretical and experimental studies
Development of risk theory in problems of earthquake-engineering
Authors: Bogdanova M.A., Boltenkova A.A., Uzdin A.M., Chernov V.P.
Key words: damage, risk, variance of the damage density function distribution, the summation of risk, seismic risk
The results obtained over the past 15 years on the development of the risk theory worked out in the 60s of the last century under the guidance of academician L. V. Kontarovich are considered. In addition to the mathematical expectation of damage (risk), its variance and the distribution density function are considered. Problems of summing up risks by objects and events are considered. The paper is dedicated to the memory of V. V. Sigidov, who started working in this direction 15 years ago.
Safety of earth structures, bases and foundations
On the seismic analysis of the NPP transportation portal
Authors: Tyapin A.G., Antonov N.A.
Key words: seismic response, structure-soil-structure interaction, force method
The main problem with the transportation portal analysis is the difference in the seismic response motions of the portal base and the main building. Besides, though one can reasonably assume that the portal does not change the motion of the main building, the opposite assumption is doubtful: heavy and large main building obviously impacts the response of the portal base both via the upper portal beams and via common soil. One should also account for the flexibility of the portal base. The authors propose the methodology of analysis for this structure.
Safety of hydraulic structures
Design for management of damage accumulation scenario of the elevated berth
Authors: Nazarova Sh.Sh., Uzdin A.M., Simkin A.Yu., Us P.V., Shulman, S.A.
Key words: sea pier, flyover type, seismic impact, damage accumulation, scenario
Scenarios of damage accumulation in a sea pier of a flyover type during strong earthquakes are considered. To manage the scenario of damage accumulation, it is proposed to divide the berth in the longitudinal direction with a seam, and to connect the divided parts using friction-movable joints. Under weak earthquake actions, the berth works as a whole one. Under strong actions, separate oscillations of the coastal and marine parts occur, and the parts interact with one another by the friction forces in the joint. In this case, the piles are not damaged, and the residual movement in the friction-movable joint is the only damage of designed structure. After an earthquake shifts in the joints are easily eliminated, and the berth takes its initial position.
Design analysis, design of components, buildings and structures
Nonlinear calculation of the frame taking into account plastic zones by the displacement method
Authors: Potapov A.N.
Key words: displacement method, yield strength, stress, plastic zone, bending moment, stiffness
An approach for calculation of statically indefinable frames taking into account plastic zones by the displacement method using a hardening diagram is proposed. An algorithm allowing to transform plastic zones to the zones of equal resistance in seismic resistant structures is given. Two simplifying presuppositions are introduced, with the help of which a stress-strain state is modeled in the elastoplastic and plastic zones. For a given length of the plastic zone incremental equations of displacement method are written which establish the connections between the increment of bending moment and the increment of load. At each step of the loading the length of plastic zone and the corresponding ultimate load are determined.
Seismic isolation of buildings and structures
Some features of assessing the seismic resistance of medical complexes
Authors: Nazarova Sh.Sh.
Key words: seismic stability, seismic isolation, floor accelerograms, floor spectra
Some features of ensuring seismic stability of medical institutions are considered. It is noted that the recommendation of seismic isolation of such institutions is due to the requirements of equipment operability during design earthquakes. In the absence of seismic isolation, it is necessary to construct floor accelerograms and floor spectra in according to which medical equipment is to be selected. If necessary, local seismic isolation can be used for seismic protection of patients and equipment, for example, in the form of a vibroprotective covering or cork floor.
Design analysis, design of components, buildings and structures
Some problems of seismic vibrations
Authors: Altyntseva E.L., Lisova O.V., Uzdin A.M.
Key words: wires, seismic oscillations, equations of motion, displacements of supports, Mathieu-Hill equation, small displacements, approximate solution
The paper is a polemic one. It responds to numerous publications of E. N. Kurbatsky et al about response spectra, Fourier spectra and dynamic coefficients. In the first part the author discusses the implementation of the term «dynamic coefficient», historically used in the Soviet and Russian codes as a synonym to the term «normalized response spectra». The author agrees that «normalized response spectra» is indeed more accurate term. However, «dynamic coefficient» is not at all absurd, if treated as the transformation coefficient to the dynamic solution not from the static solution with constant loads, but from the maximal quasi-static solution with time-dependent loads. In the second part of the paper the relation between Fourier spectra and response spectra is discussed. The author points out at the possible mistakes in the publications considered in the formulae describing this relation.
