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DESTRUCTION MODEL OF IDEALIZED CONCRETE STRUCTURE BY SAWING

https://doi.org/10.34031/2618-7183-2020-3-2-46-54
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 46-54 p.
Abstract
The requirements of modern construction are the strength of building structures, as well as low cost. It is these conditions that provide new technologies that are constantly being improved. The article is devoted to the consideration of cases of a probabilistic approach to solving the problem of theoretical energy consumption for the destruction of concrete of ideal structure.
The processes of concrete deformation and its destruction are studied by building mechanics. Concrete is a multicomponent material, which presents a certain difficulty in the study of crack formation. In operating conditions, the concrete/reinforced concrete structure is affected by the properties of its constituent materials; therefore, one of the most important tasks is the selection of criteria that can comprehensively characterize the basic parameters of concrete. Obtaining the strength characteristics of concrete of operated structures remains an urgent task. The article proposes to consider the ideal structure of concrete. The features of this structure are the symmetry of fracture along two principal planes. The destruction of concrete was carried out by sawing individual strips of concrete. Moreover, to describe the sawing process, the authors proposed a model of a symmetric structure of concrete in which aggregate grains are idealized. They are presented in the form of balls in the body of concrete.
The features of the sawing process are revealed. The analytical dependencies of fracture sawing the ideal structure of concrete are obtained.
Conclusions are drawn about the possibility of using the ideal model for obtaining the strength characteristics of concrete. The analysis of symmetrical ideal concrete compositions with various variables is performed. The significance of the work done lies in the possibility of transferring the research results to real buildings and structures and solving the main tasks that are posed in the study.
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THE INFLUENCE OF SEVERAL TYPES OF RESINS ON THE DYNAMIC MECHANICAL PROPERTIES OF POLYMER MIXTURE BASED ON BUTYL RUBBER

https://doi.org/10.34031/2618-7183-2020-3-2-36-45
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 36-45 p.
Abstract
This work is devoted to the problem of developing vibration-damping polymer materials with high damping properties in a wide temperature range. The study of the effect of modifying additives on the strength, damping, adhesive and cohesive properties of a butyl rubber composite is the aim of this work. The task is to identify the actual temperature, frequency, dynamic and mechanical characteristics of a composite material based on butyl rubber depending on the type and concentration of resins. The key methods for studying this problem is the dynamic mechanical analysis method, aimed at obtaining information about changes in the dynamic properties of polymer materials (bond strength with metal when peeling samples of composites, determining the flow resistance of samples, determining the migration of plasticizer). Due to the established experimental dependences, it was found that the addition of resins (3% by weight) in the composition based on butyl rubber leads to an increase in the damping properties of composite materials, and an increase to (4.25% by weight) leads to their decrease. It was established that the obtained filled mixtures with a high damping peak and good adhesive and strength properties are mixtures with the addition of alkyl phenol-formaldehyde resins.
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NUMERICAL ANALYSIS OF EARTH DAM STRESS-STRAIN STATE UNDER SEISMIC IMPACT CONSIDERING THE WAVE DYNAMICS

https://doi.org/10.34031/2618-7183-2020-3-3-5-20
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 5-20 p.
Abstract
The design, construction and operation of high-rise earth dams in seismic regions, such as the territory of the Republic of Uzbekistan, requires constant improvement of the methods to calculate them under various loads, both of a static nature (gravitational forces, hydrostatic, etc.), and of a dynamic nature, including seismic effects. Emergency situations at such facilities or their partial destruction under any impact can lead to disastrous aftermath. The aim of this study is to develop a mathematical statement and an algorithm for numerical solution to an unsteady-state problem for an earth dam in a plane elastic statement. To verify the proposed methodology and the corresponding complex of applied programs, a solution to the test problem was given (the Lamb’s problem). According to the developed methodology and algorithm based on numerical method of finite differences, the problem of studying the stress-strain state was solved under shear stress on the foundation (in the form of a seismogram) on the example of the high-rise Charvak earth dam located near Tashkent city. The solution is presented in the form of distribution lines of equal displacements, stresses along the dam body, depending on time. The most vulnerable zones of the earth dam under consideration were identified.
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MINERAL WOOL COMPOSITE WITH THE USE OF SAPONITE-CONTAINING MINING INDUSTRY WASTE

https://doi.org/10.34031/2618-7183-2020-3-3-21-27
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 21-27 p.
Abstract
The paper shows the possibility of producing a thermal insulating composite based on basalt fibers and saponite-containing mining waste. A method for manufacturing thermal insulating composites from hydro-mass with different contents of the mixture components is proposed. Basalt fibers were used as a filler, and pre-mechanoactivated saponite-containing material (SCM) was used as a binder. It was found experimentally that depending on the composition of composites, the coefficient of thermal conductivity varies from 0.1109 to 0.1342 W/(m•K), and the compressive strength – from 0.45 to 0.93 MPa. In addition, it was found that thermal modification of composites at temperatures up to 1200°C significantly (up to 3 times) increases the compressive strength of composites, while not affecting the coefficient of thermal conductivity. The experiments to determine the conductivity of the composite “basalt fiber – SСM” depending on its moisture content showed that the obtained composite is characterized by intense and linear increase in the values of conductivity when the humidity of the sample to 12% and further increase in humidity practically does not change the values of the coefficient of thermal conductivity. Comparison of the studied thermal insulation composite with known structural thermal insulation materials in terms of its thermal insulation and strength characteristics showed that it is comparable to gas and foam blocks. It should also be noted that this material is environmentally safe and can withstand high temperatures without collapsing.
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USE OF IRAQ CONCRETE SCRAP AS FILLER AND AGGREGATE OF HEAVYWEIGHT AND LIGHTWEIGHT CONCRETE

https://doi.org/10.34031/2618-7183-2020-3-3-28-39
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 28-39 p.
Abstract
The relevance of the paper is due to the search for alternative sources of raw materials for the construction industry, associated with the disposal of man-made waste. The novelty of the article is to identify the sci-entific laws of the influence of demolition waste on buildings and structures on the formation of the microstructure of lightweight and heavyweight concrete. Concrete waste was prepared as both fillers of cement materials and fine aggregates, based on which concrete with high mechanical properties was created. The mix design was carried out from the point of view of geomimetics, in particular, taking into account the law of affinity of structures. The strength characteristics of concrete mixtures were investigated in accordance with EN 12390-3. In addition, the microstructural, morphological and thermal properties of the raw materials and concrete were determined during 28-day curing. For the first time, the dense microstructure of the composite was ensured, both with Portland cement products and with hydration, and, in part, with hydration products of previously unreacted clinker, whose minerals are present in concrete waste and are activated when they are crushed. The use of demolition waste of buildings and structures as a filler of cementing material when replacing Portland cement up to 20% allows to obtain better compressive strength of both heavyweight and lightweight concrete.
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CERAMIC BUILDING MATERIALS USING NON-TRADITIONAL RAW MATERIALS

https://doi.org/10.34031/2618-7183-2020-3-3-40-46
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 40-46 p.
Abstract
The paper raises questions about the search for the possibility of obtaining a construction ceramic material using a special type of raw material component. Diopside concentrate was chosen as the basis for the ceramic masses due to its positive parameters necessary to improve the strength properties of the material and to support local deposits of raw materials in the East Siberian region. To reduce the optimal firing temperature, an aqueous-alkaline solution of sodium silicate was used in small quantities. The chemical composition of the diopside rock showed mainly the presence of silicon oxides. X-ray diffraction analysis revealed the presence of diopside, quartz and calcite. Sodium-silicate glass is characterized by a full content of silica and a modulus of 3. Using the state diagram of three-component systems, the temperature limits necessary for sintering ceramic masses are established. The fusibility curves show that at a temperature of 1040oC, the values of the primary melt for various compositions are 4-14%, and the total melt content is observed at 1475oC. The parameters of physical and mechanical properties of the ceramic material were determined, where at the firing temperature of 1000-1100oC the value of fire shrinkage was no more than 1%, water absorption up to 10%, and compressive strength up to 31 MPa. Moreover, with an increase in the amount of diopside to 90% by weight, the strength increases, and shrinkage decreases. X-ray phase analysis of the compositions determined mainly analytical lines of diopside, which begin to decrease by 1000oC, which determines the relationship with the liquid glass. The DTA and TG curves of the thermogram showed endothermic and exothermic effects due to the release of adsorbed water and crystallization of glass. The possibility of obtaining high-strength low-shrink ceramics using diopside raw materials as the basis of ceramic masses when adding sodium-silicate glass in the form of a melt is established.
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PROGRAM OF EXPERIMENTAL STUDIES OF THE LOAD-BEARING CAPACITY OF GIRDERLESS PLATES FOR PUSHING UNDER DYNAMIC LOADING. DESIGN OF PROTOTYPES

https://doi.org/10.34031/2618-7183-2020-3-3-47-53
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 47-53 p.
Abstract
This article presents a program for experimental research of the behavior of reinforced concrete slabs when forced through in static and short-term dynamic loading modes. At hazardous production facilities, there is always an increased probability of emergency situations of disaster nature that lead to explosions and are characterized by a sharp increase in the front, a short duration and a wave character. Taking into account the placement of complex technological processes in buildings, it is now necessary to implement “flexible” space-planning solutions, for example, the use of girderless floors. The need to perform these studies is also due to the lack of methods and regulatory documents that regulate the calculation of the penetration of unbalanced monolithic slabs under dynamic loading. The purpose and objectives of this program are: to assess the influence of the thickness of the slab part of samples and the concrete class on the strength and crack resistance of elements, to obtain new experimental data describing the processes occurring in concrete and reinforcement, to identify patterns of destruction of samples. The test was carried out on a test stand based on a copra rig. The choice of sizes of prototypes is determined by the technical characteristics of this installation, the tasks of the experiment, the possibilities of manufacturing and testing models, and obtaining sufficiently reliable values of the parameters under study during testing. Twelve samples were tested for short-term dynamic loading and four samples for static loading. The following parameters vary: the concrete class (B15 and B20) and the thickness of the slab part of the sample (100 mm and 120 mm). The paper describes the dimensions, reinforcement, concrete classes of the studied samples, the sequence of work in the manufacture of samples, taking into account the installation of load cells. The result of this work is the development of a test method for prototypes.
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HISTORICAL RESEARCH OF MODERNISM IN AFRICAN ARCHITECTURE OF LOW-RISE SOCIAL HOUSING

https://doi.org/10.34031/2618-7183-2020-3-2-55-62
 55-63 p.
Abstract
The purpose of this study is to examine the emergence of modernism as a cultural response to the conditions of modernity to change the way people live, work and react to the world around them. In this regard, the following tasks were formulated: 1) study the development of modernism on the world stage, 2) identify its universal features, and 3) analyze how the independence of Central and sub-Saharan Africa in the 1950s and 1960s coincided with a particularly bright period of modernist architecture in the region, when many young countries studied and asserted their identity in art. The article analyzes several objects of modernist architecture in Africa: urban development projects in Casablanca (Morocco), Asmara (Eritrea), Ngambo (Tanzania). The main features and characteristics of modernism which were manifested in the African architecture of the XX century are also formulated. It is concluded that African modernism is developed in line with the international modernist trend. It is also summarized that modernism which differs from previous artistic styles and turned out to be a radical revolution in art is their natural successor.
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INNOVATIVE TECHNOLOGIES IN CONSTRUCTION AND THEIR USE IN ORGANIZATIONAL AND TECHNOLOGICAL EVENTS

https://doi.org/10.34031/2618-7183-2020-3-1-7-13
 7-13 p.
Abstract
The purpose of the article is to analyze modern innovative technologies in construction and to develop a method of network planning in construction based on the BIM model.
A clearly defined goal allows to identify the main tasks aimed at its implementation:
- analysis of practical and theoretical experience in the field of innovative technologies at various stages of construction production;
- identification of the research direction and theoretical justification of the chosen direction;
- justification of the practical effectiveness of the selected areas;
- defining a list of innovative methods that serve as a basis for further analysis and conclusions:
- design of the object network planning system based on BIM technologies and network design.
In this work, it is planned to show the algorithm of operations for the use of calendar planning on mass construction sites, adapted for different situations.
The research work allows identifying the advantages of using information modeling of buildings for the stage of operation of the object. The developed basic methodology for organizing functional processes can help improve the established system of housing stock operation. Based on the experience of this study, it is possible to develop this topic in the field of network planning and implementation on practical objects.
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CALCULATION OF HIGH-RISE BUILDINGS UNDER SEISMIC EFFECT OF “CONTROLLING EARTHQUAKE” LEVEL BY NONLINEAR STATIC METHOD ON THE EXAMPLE OF ADYGHE WIND POWER PLANT

https://doi.org/10.34031/2618-7183-2020-3-1-14-20
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 14-20 p.
Abstract
The aim of this work is to test a multi-modal nonlinear static method for seismic impact of the "controlling earthquake" level for high-rise structures on the example of a wind power plant (WWP) with a capacity of 1.5-2.0 mW of the Adyghe WPP using computer modeling in the LIRA 10.10 PC. Additionally, the results were verified in the PC “Ansys”. The main bearing element of the WWP is a tower-pipe with a weak taper, the material of which is high-strength steel S355. The assessment of the structure seismic resistance is performed in physically and geometrically nonlinear settings. At the same time, the Vaughn-Mises strength theory was used for steel. Comparison of the calculation results proves the effectiveness of the multi-modal nonlinear static method. The method under consideration has a number of advantages: tolerance to the initial data in terms of numerical description of the seismic impact, less machine capacity of the calculation in comparison with the direct dynamic method, and the ability to automate the calculation process fully.
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