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 Structural Mechanics of Engineering Constructions and Buildings


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№ 5, 2017

C o n t e n t s and A b s t r a c t s

85 Years to Valentin Alekseevich Kopnov
4
Geometrical investigations of middle surfaces of thin shells
Romanova V.A., Thoma Anamariya. Automatic modeling of the surfaces of the equal slope in AutoCad system through language AutoLisp. Summary Graphical computer modeling is a real possibility of solving problems on the formation of surfaces by a kinematic method. It is due to the presence of automated design systems, such as MathCad, Mathematika, AutoCad, etc. The advantage of the AutoCad system is the presence of the built-in language of functional AutoLisp. Having a wide range of mathematical functions and functions for drawing graphic objects, the AutoLisp language allows you to write a program for drawing shells of any complexity, in a particular case - shells of the same ramp on the elliptical plane, the surface of the involute helicoid, and then transferring the results to the AutoCAD environment. Playing objects in slow motion makes it possible to compose mini-films about the formation of surfaces. The image of graphical constructions in three-dimensional space using the AutoCAD color palette enhances the expressiveness of the image of surfaces and their elements. The aim of the study is the possibility of modeling the surface of the equal slope ramp on an elliptical plane, carried out by its gradual drawing in a slow dynamic mode with the creation of a mini-film that allows the surface to be displayed on the monitor screen. KEY WORDS: equal slope surface, modeling, AutoLISP, AutoCAD, shell, shaping, layer, generatrix, developable surface, elliptic plane.
5
Theory of elasticity
Bakushev S.V. Evaluation of the coefficient of transverse deformation at the axial-symmetric deformation of continuous medium. Summary The article is devoted to the question of theoretical estimation of the value of the coefficient of transverse deformation in continuous medium under the conditions of axial-symmetric deformation. It is shown that the value of the coefficient of transverse strain essentially depends both on the mechanical characteristics of the material of the half-space, the level of development of the stress-strain state at considering point, and on the type of the mathematical model of the continuous medium (geometrically linear or geometrically nonlinear) and may exceed the limit value for linear- elastic body, equal to 0,5. Keywords: Solid array, Axial-symmetric deformation, Coefficient of transverse deformation, Geometrical and physical nonlinearity.
12
Plekhanov F.I. Distribution of load and bending stresses along the length of the thick plate fixed in the base when an initial angle between it and the detail contracting with  it. Summary The paper describes a method for determining coefficients of load and bending-stress distribution along a rigidly fixed thick plate which is in edge contact with the other part when no load is applied. The method is based on the solution of integral Volterra equation which binds angle between contacting elements and components of strain. Keywords: fixed thick plate, contact, load, bending stress.
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Haciyev V.C., Mirzayeva G.R., Shiriev A.I. On free vibration of a nonhomogeneous orthotropic rectangular plate on a nonhomogeneous visco-elastic foundation. Summary In the paper, by using approximate analytic methods, the study a problem of vibrations of a nonhomogeneous rectilinear plate and a visco – elastic foundation, the boundary conditions are homogeneous. It is assumed that the modules of elasticity and density of the plate are characteristic functions of three space coordinates, the Poisson ratios are accepted to be constant [1]. The numerical calculation is carried out under specific values of characteristic functions, characterizing the properties of the plate and foundation, and the results are represented in the form of tables and dependence graphs. Key words: plate, continuity, orthotropic, density, foundation, frequency, elastic module, motion equation.
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Analysis and design of building structures
Utkin V.S., Solov’ev S.A. Reliability analysis of reinforced concrete beams with shear cracks on rebar strength. Summary The article describes methods for reliability analysis of reinforced concrete beams with shear cracks by the criterion of the rebar strength. Reliability analysis is conducted on the basis of the provisions of reliability theory and fuzzy set theory to account for the limited statistical information on controlled parameters. We considered two design cases with different numbers of fuzzy variables in the design mathematical models of a limit state. Numerical examples of reliability analysis are given. The proposed methods may in some cases contribute to accidents prevention in reinforced concrete beams, and in other cases get the economic effect from the rejection of strengthening or replacement of beams, even when the crack width exceeds the ultimate value. KEY WORDS: reliability, safety, reinforced concrete beam, shear cracks, strength criterion, possibility theory, fuzzy sets
34
Semenov D.A. Evolution of normative approach to analysis of reinforced concrete structural elements. Summary Strength analysis of cross-sections, stiffness and cracks width calculations, P-delta analysis of strucural members are reviewed within Russian Codes. Primary calculation tool of the modern Code is non-linear “deformation model”. It is noted a saturation of normative approach by the empirical coefficients. Development of advanced models, decreasing a role of empirical component of reinforced concrete theory, is seemed to be one of the ways to Code improvement. KEY WORDS: review of codes, analysis of reinforced concrete structures, strength, stiffness, stability.
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Kirsanov M. N. Analysis of the deflection of the arched truss. Summary The geometry of the flat statically determinate truss with two fixed hinge supports is specified by the lengths of the rods, the number of panels in supporting parts and the number of panels in the bolt. By induction on these parameters the General formulas for the deflection of the trusses under the action of concentrated and distributed load are obtained. Symbol conversions are performed in the system of computer mathematics Maple. The asymptotic properties of solutions are found. Formulas for reactions of supports and efforts in the most compressed and stretched the rods of the truss are found. KEY WORDS: truss, lattice, Maple, deflection
50
Numerical methods of structures’ analysis
Bautdinov D.T., Djamaludinov D.T. The finite element stress state analysis of underground hydraulic erections taking into account the anisotropy of the medium. Summary In this article, the stressed state analysis of a transverse-isotropic rocky soil near a hydrotechnical tunnel is carried out. The cross section of the tunnel is circular. The load considered in the analysis is the self-weight of the surrounding soil. The analysis is carried out for various resilient characteristics of the soil and in the orthogonal directions for various slopes. The slope of the plane of isotropy models a sloping bedding of layers of earth. The slope of the plane of isotropy models a sloping bedding of layers of earth. The tangential stresses are defined at the entry line. This allows estimating the strength of the surrounding soil for various laying depth. KEY WORDS: deformation module, Poisson's ratio, transverse-isotropic medium, theory of elasticity
56
Buckling analysis
Inozemtzev V.K., Redkov V.I., Zhestkova S.A., Inozemtzeva O.V. Calculation of overall sustainability of structures with the high centre of gravity. Summary The article deals with overall sustainability of stiffening diaphragm of support structures in engineering construction in the context of structural elements collaboration as a system «high rise construction- foundation (base)- ground base». Calculations were made in the program complex LIRA-CAD. It was found out that the general stability of the bearing systems, which are paired diaphragms of rigidity in the form of support structures of a large-span structure with a highly located center of gravity, depends on their location on the base plate. Key words: supporting structures with a high center of gravity, stability, critical load.
61
Experimental researches
Yakupov S.N., Harislamova L.U., Yakupov N.M. Change of mechanical properties of thin-layer membranes under the influence of liquid medium. Summary Thin-layer membranes and membrane compositions find application in different industries as independent design elements and as coatings. With the development of new technologies, functional coatings are become increasingly widespread. During the process of exploitation design elements and coatings interact with the environment. For the competent design of structures with thin-layer membranes, it is necessary to know the influence of the liquid medium on the change in their mechanical properties. The results of experimental studies on the topic under consideration are presented. KEYWORDS: Thin-layer membranes, membrane compositions, mechanical properties, liquid medium, time, experimental-theoretical method
66
 Alkadi S.A., Demyanov A.I., Osovskih E.V. Experimental researches of survivability fragment of the frame of the building with reinforced concrete composite elements working on bend with torsion. Summary In the article, the experimental results of deformation, cracking and failure of a reinforced concrete frame when loaded over the designed specifications, or when overloaded by a sudden failure of a pillar are presented. The results of displacements and cracking caused by the load at the main support points, for bending and twisting, give an opportunity to determine the survivability parameters and the dynamic overload values for the construction elements. The results can also provide information about the survivability of a building after being overloaded. KEYWORDS: experimental studies, vitality, the impact of beyond design basis, progressive collapse, reinforced concrete component, bend with torsion.
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