Vol 15, No 5 (2019)

Analysis and design of building structures
Development of a method for calculating the stress state in horizontal sections of hydraulic engineering angular-type retaining walls
Rubin O.D., Lisichkin S.E., Pashenko F.A.
Abstract

Angular retaining walls are widespread in hydraulic engineering. They are characterized by large dimensions, small percentages of reinforcement, block cutting along the height of the structure. The bulk of the existing retaining walls were built in the 1960s-1980s. The regulatory documents that were in force during this period had certain shortcomings that caused the non-design behavior of a number of retaining walls. Improvement of calculation methods for reinforced concrete structures of retaining walls is required, within the framework of which a more complete account of the characteristic features of their behavior is needed. The aim of the work is to improve methods for calculating reinforced concrete retaining walls of a corner type. Methods of research carried out to improve the calculation of reinforced concrete retaining walls of the corner type included, among others, the classical methods of resistance of materials, the theory of elasticity, and structural mechanics. To determine the actual stress-strain state of the natural structures of retaining walls, visual and instrumental methods for examining retaining walls were used, including the method of unloading reinforcement. Results. To determine the stress state in the elements of the reinforced concrete structure of the retaining wall (in concrete and in reinforcement), a methodology was developed for calculating the stress state of retaining walls, which allows to determine the components of the stress state (stress in concrete in the compressed zone, as well as stress in stretched and compressed reinforcement) in horizontal sections of the vertical cantilever part of the retaining walls.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):339-344
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The concept of development of computer aided design programs for bridges or other engineering structures according to the specified criterion of optimality
Salamakhin P.M., Chasovnikov A.D.
Abstract

In article on the basis of generalization of experience of creating in the period from 1997 to 2015 computer-aided design of various bridge structures by fifteen graduate students of the Department of Bridges and Transport Tunnels MADI (GTU) under the leadership of Doctor of Technical Sciences, Professor P.M. Salamakhin the authors proposed the concept of the development of the structure of standard programs of computer-aided design of bridge or other engineering structures according to the given optimality criterion. Given in the most general form of the complete block diagram of such programs with the detailed disclosure of the indicator of simultaneous execution of a set of requirements in all elements of the structure dependent scale in the sequential approach the minimum possible values, and also demonstrates how to determine the combination of values of all independent parameters of structures that provide the design of facilities according to the given optimality criterion. When working on the article, some provisions of earlier studies and the state of development of automation of design of bridge structures abroad are taken into account. The authors proceed from the fact that the proposed concept of development of computer-aided design of bridge and other engineering structures according to the specified criterion of optimality can and should be used as a model in the development of computer-aided design of structures with various generalized design schemes.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):345-352
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Theory of plasticity
The study of marginal deformations of the leaf extracts with regard to plastic thinning and destruction of the material
Morozov Y.A.
Abstract

The aim of work. The paper analyzes the process of sheet drawing and develops a method for determining the minimum curvature of the torus fillet in the formation of a cylindrical product (glass), taking into account the plastic thinning of the deformable material by the end edge of the pressing punch. Methods. The existing scheme of forming with the use of permissible coefficients of drawing and tensile strength of the material, representing the basis of deformation-force calculation, which often ignores the factor of deformation thinning and its impact on the strength of the material, which together can lead to excess of the allowable stress in the material, causing its rupture, is analyzed. A mathematical model of the volume stress state of the metal is developed, which allows to estimate the value of the thinning in the formation of the torus surface of different curvature, followed by the approximation of the values found by a polynomial function. Considering the criterion of limit loads the level of radial stresses during folding and stretching of the sheet material, taking into account its thinning, the minimum curvature of the torus surface of the glass is established. Results. The results obtained will allow to simulate the stress-strain state of the metal in the development of sheet drawing technology: to establish the value of thinning and to estimate the level of radial stresses in the formation of the torus surface rounding to prevent the destruction of the elongated glass (separation of the bottom), which guarantees quality products.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):353-359
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Comprehensive view on the ductility of basalt fiber reinforced concrete focus on lightweight expanded clay
Galishnikova V.V., Chiadighikaobi P.C., Emiri D.A.
Abstract

Relevance. Ductility of basalt fiber reinforced concrete is an interesting property of basalt fiber reinforced concrete. However, very few experiments on this property is documented. The aim of the work. This paper provides a summarized analysis and review of existing publications on the ductility of lightweight basalt fiber reinforced concrete. Methods. This paper provides a comprehensive study on ductility of basalt reinforced concrete and lays the framework for proper laboratory experiment on the ductility of basalt fiber reinforced concrete. Results. From the findings of this review paper, ductility of dispersed basalt fiber reinforced concrete depends not only in the percentage of basalt fiber in the concrete but in the length and diameter of the basalt fiber. Increase in the percentage of basalt fiber in the concrete yielded an increase in the concrete ductility.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):360-366
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Theory of thin elastic shells
Optimization study of shape of translational shell of square plan
Tupikova E.M.
Abstract

The aim of the work. The static analysis and comparison of the results for translational shells under equally distributed load of dead weight are provided. The shells of the similar general dimensions in plan and rise of four different types: translation of catenary along catenary, circle along circle, ellipse along ellipse and sinusoid along sinusoid are investigated. Methods. The finite element method was applied for the analysis. The research was conducted for the shells of material of

reinforced concrete characteristics. Results. The comparison has shown that shells of catenary and circle translation surface demonstrate the most advantageous behavior under loading; the worst results for reinforced concrete were got for ellipse along ellipse translation shell. The peculiarities of each type behavior were revealed, that is of interest for their prospective reduction to practice of structural design.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):367-373
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Numerical methods of structures’ analysis
Comparative analysis of the results of determining the parameters of the stress-strain state of equal slope shell
Ivanov V.N., Alyoshina O.O.
Abstract

Relevance. Thin-walled structures of shells constitute a large class in architecture, in civil and industrial construction, mechanical engineering and instrument making, aircraft, rocket and shipbuilding, etc. Each surface has certain ad-vantages over the other. So the torso surface can be deployed on the plane of all its points without folds and breaks, with the length of the curves and the angles between any curves belonging to the surface, do not change. The investigation of the stressstrain state of the equal slope shell with a director ellipse at the base is presented to date in a small volume. The aim of the work. Obtaining data for comparative analysis of the results of the stress-strain state of equal slope shells by the finite element method and the variational-difference method. Methods. To assess the stressstrain state of the equal slope shell, the SCAD Office computer complex based on the finite element method and the “PLATEVRM” program, written on the basis of the variational-difference method, are used. Results. The numerical results of the stress-strain state of the equal slope shell are obtained and analyzed, the pros and cons of the results of calculations by the finite element method and the variational-difference method are revealed.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):374-383
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Dynamics of structures and buildings
The research of the stress-strain state with local thinning in pipelines and determination of allowable values of concentration stress and strain
Kuzmin D.A., Andreenkova A.V.
Abstract

Relevance. The nuclear power plant contains a large number of equipment and pipelines subject to flow acceleration corrosion. As a result of a combination of various parameters - sizes (diameters, wall thickness), operational parameters (internal pressure, temperature), steels and elements types - the number of design cases is tens of thousands, without counting the possible forms of thinning. The process of maintenance and repair at the stations are doing an assessment of the accordance of actual and allowable values of wall thicknesses. The ensuring safe operations of equipment and pipelines have been introduced correction functions for regulatory functions, taking into account the forms of thinning, to determine the permissible thinning. The aim of the work. The task is to determine the influence of the forms and types of thinning on the stress-strain state and to determine the most critical thinning for straight sections of pipelines subject to flow acceleration corrosion taking into account emergency conditions. Methods. The allowable values of stress concentration factors (deformations) of pipelines subject without flow acceleration corrosion was determined taking into account allowable values, the requirements of the federal norms and rules for emergency operating conditions. For researches of the stress concentration coefficients were used the finite element method and analytical methods for various shapes, sizes and depths of thinning. Results. A method has been developed, that allows getting the maximum allowable values of stress concentration factors (deformations) for emergency operation, which afford to determine the maximum allowable depth of thinning in emergency conditions - an above criterion. The researches have been carried out definition of the stress concentration factors for local thinning with various types of these thinning. The functions of concentration coefficients depending on the geometric parameters of local thinning wall thickness were determined for a straight section of the pipeline. As a result of the research, the dependences of the sizes of thinning on the concentration coefficients for straight pipelines were created and a master-curve was obtained. The researches were carried out take into account the load from internal pressure and bending moment.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):384-391
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Calculation of seismic qualities of the damper and vibration transducer with the possibility of their use in aircraft
Madzhidov I.U., Aripkhodzhaeva M.B., Rakhmatova D.M., Suleymanov A.A.
Abstract

The aim of the work. The article aims to determine the most effective seismic protection devices, as well as their degree of reliability in different conditions. The method of comparative calculation for determining the quality of seismic protection devices is given. An example of calculation for the damper and vibration transducer is carried out. Calculations show that the use of seismic protection devices reduces the coefficient of K 3 more than twice. Seismic protection is an urgent problem not only in construction, but also in all branches of the technosphere. The option of using seismic protection devices in aircraft is also considered. Methods. A comparative calculation of the behavior of dampers and vibration transducer taking into account the friction coefficients f tr, the sum of vertical loads ∑ Qkd , the total shear seismic force ∑ Sdc is considered. The diagram of the location of seismic protection devices (damper and vibration transducer) under the building is presented, as well as the options for installation in aircraft are given. Comparative calculations are carried out with the presence of seismic protection installations and without them. Results. The total result is given taking into account the change in the value of horizontal seismic loads Sik , which has changed in the range of 2.26-2.46 times. This circumstance allows to conclude that the proposed damping device reduces the seismic load, which falls on the protected structure, by 1-2 points, with almost the same efficiency as the vibration transducers (difference of 0.3 times).

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):392-398
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Experimental researches
The use of fixed points in experimental research of the internal friction of material
Zylev V.B., Platnov P.O.
Abstract

The aim of the work. The work is devoted to experimental research of internal friction parameters of the material. Methods. The research of internal friction is carried out by consideration of damped oscillations of the experimental system that consist of rigid plates and a specimen in a state of pure bending. We propose to locate bearings in the fixed points to minimize energy losses in support fastenings. Fixed points are determined by using a finite element complex with consideration of free oscillations of the loose model. Results. Damping curves were determined, which demonstrate a very small logarithmic decrement of oscillations and frequency independence of inertial friction. The main result of the work is the tested improvements of the experimental technique, among which the main one is the use of fixed points for determining the places of fastening of the laboratory installation

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(5):399-404
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