Technical regulation and development of design codes
Questions about the development of standards for the design of earthquake-resistant construction of a new generation
Authors: Guryev V.V., Dorofeev V.M.
Key words: earthquake-resistant construction, design standards, earthquake intensity scale, seismological information, OSR, DSR, MSR, calculation methods, categories of technical condition
Deals with the composition of the design standards of earthquake resistant construction of new generation in the jobs pane of seismic hazard according to General and detailed seismic zoning and microcalorimetry and applications of models and methods for calculation of buildings and structures on seismic excitation. The necessity of switching the seismic hazard assessment from the MSK-64 macroseismic scale to the MSHIZ-18 macroseismic scale is indicated. The seismological information required for calculations of buildings and structures is given and the form of its representation in the normative document is proposed. Noted the importance of establishing a connection, limit state of structures with the categories of the technical state of objects under seismic excitation normalized level, streamlining of the use of certain models and calculation methods for different types of buildings and structures, including with regard to their responsibility, communication performance of the models and calculation methods of buildings and constructions given in the norms of seismological information.
Seismic isolation of buildings and structures
Seismic isolation of bridges
Authors: Kurbatskiy E.N., Titov E.U., Baev L.V.
Key words: seismic isolation, seismic isolation devices, special response spectra
Bridges, and especially large-span bridges, are vulnerable to earthquakes and are severely damaged and sometimes destroyed by strong earthquakes. Seismic isolation devices can significantly reduce the impact of earthquakes on bridges. Therefore, engineers who design and construct bridges in areas of high seismic activity must be able to apply the various types of isolators that need to be used in such conditions. The paper presents the designs of modern seismic isolation devices for bridges and the requirements for them. To assess the influence of seismic isolation parameters on the bridge»s response to an earthquake, special response spectra are used in the form of the dependence of the spectrum of maximum accelerations on maximum displacements, which are not even mentioned in the Russian regulations. The reaction of structures to seismic effects when using seismic isolation devices is analyzed. The main types of seismic-insulating support parts, which have received the widest application in practice in recent years, as well as their mathematical models are considered. In the Code «Transport structures in seismic areas» there is not a word about seismic isolation of bridges. Antiseismic devices of bridges «stoppers» and «buffers» have nothing to do with seismic isolation
Safety of earth structures, bases and foundations
Resonant properties of soils in the territory of Yalta (Crimea)
Authors: Pustovitenko B.G., Eredzhepov E.E.
Key words: resonant properties of soil, medium model, amplitude-frequency characteristics, seismic stiffness
The results of studying the amplitude-frequency characteristics (AFC) and resonance properties of soils in the territory of Yalta are presented. The spatial grouping of frequencies amplifying seismic vibrations is obtained. The highest gain and lowest frequencies are noted on soils with a layer with reduced seismic stiffnesses. Quantitative correlation dependences of the spectral characteristics of the medium on the power of the first nearsurface engineering-geological element (IGE-1) with reduced seismic rigidity (ρV ≈ 1000 g / cm2 в s) in the soil massif classified as seismic category II were obtained. With an increase in the thickness of the IGE-1 layer from 0 to 10 m, the reinforcing properties of the soil for transverse vibrations
(S) increase by about 5 or more times, and for longitudinal (P) — by almost an order of magnitude. In this case, the resonance frequencies fP and fS, respectively, decrease by 1,5 and 2 times, i. e. they are shifted to the lower frequency region, the most dangerous for construction sites.
Numerical simulation of the situation of occurrence of additional deformations of the base of the
foundations of a new construction object during vibration extraction of sheet piles
Authors: Mangushev R.A., Polunin V.M.
Key words: sheet piling vibration, dynamics, liquefaction, finite element method, additional building deformations, geotechnical monitoring
The results of numerical simulation of vibration extraction of sheet piles in the geotechnical finite element software package Plaxis are presented. It is noted that in the process of vibrating elements in dispersed water-saturated soils, a change in the soil structures occurs in the near space of sheet pile, which must be taken into account in the process of predicting the deformation of buildings during construction work. Calculations are carried out to determine the propagation of vibrations in the soil, and the values of vibration accelerations in the Plaxis dynamic module are obtained. The values of additional precipitation of the building under consideration, determined during the static calculation, are compared with the values of vertical deformations according to the results of numerical calculation and monitoring results.
Safety of components, buildings and structures
Operating experience of drum granulator dryers installed on floors of industrial buildings
Authors: Gurieva N.S., Smirnov V.V., Novitsky D.V.
Key words: BGS, crown pair, frequency of teeth re-coupling, harmonic analysis, polyharmonic character of spectra
The results of vibration survey of supporting structures of drum granulator dryers installed on the floor of the built-in floor in the industrial building of the plant for production of mineral fertilizers are given. The survey results were used to strengthen structures and reduce dynamic impacts on building structures and equipment.
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
Peculiarities of the vibrations of power transmission lines with kinematic disturbance of the supports are considered. It is shown that during seismic vibrations of power transmission line supports the tension can significantly change in the wires. A method is proposed for an approximate estimation of the vibrations of a wire under its alternating tension. It is shown that in the general case, the equations of oscillation are decomposed in variables from the coordinate and time, moreover, along the coordinate, a classical equation is obtained for finding eigenmodes of vibration, and in time for each form, the Mathieu-Hill equation is obtained. The first region of solution instability is obtained.
