ARCHITECTURE AND CIVIL ENGINEERING
BUILDING STRUCTURES, BUILDINGS AND CONSTRUCTIONS
The determination of the actual class of concrete in monolithic reinforced concrete structures is the most important factor determining the quality and strength of structures. In practice, the actual grade of concrete may differ from the design value. If this difference occurs in the direction of decreasing the actual concrete class, then the normative and design characteristics of concrete, the bearing capacity and rigidity of the structures, respectively, decrease and there is a need to strengthen the structures. Current regulatory documents allow you to determine the actual class of concrete in both continuous and spot inspection of structures. The article discusses specific examples to determine the actual class of concrete and draws conclusions about the rational use of a continuous or selective examination of structures of various types with specific examples.
The problem of designing foundations using long bored piles of large diameter is shown. Such piles are most often used in the construction of buildings and structures, on the foundations of which large loads are transferred, and such buildings are often built on sites with difficult soil conditions. When designing foundations using such piles, it becomes necessary to calculate them for horizontal load and bending moment. The article is devoted to studies of the dependence of the coefficient of subgrade reaction on the diameter of piles when calculating long bored piles of large diameter in clay soils. To determine the patt erns of changes in the coefficient of subgrade reaction from the diameter of the piles, numerical studies in a three-dimensional setting were performed. Based on the results obtained, the graphs «load – displacement» are constructed. The method of calculating the coefficient of subgrade reaction with known movements of the pile head and the applied load is shown. The regularities of changes in the deformability of the soil base with an increase in the diameter of the pile are revealed and a coefficient taking into account this dependence is proposed.
The article describes the essence of the technological method of testing a reinforced concrete beam with central prop for fire resistance without destruction, based on a set of individual indicators of the quality of concrete and reinforcement. The influence of the geometrical dimensions of a reinforced concrete beam with central prop, the heating patt ern of the calculated cross section under fire conditions, the placement of the reinforcement in the calculated cross section, the depth and degree of fire protection of the concrete, the coefficient of thermal diffusion of concrete, the magnitude of the test load on the beam and the stress intensity in the bars of the longitudinal working reinforcement were investigated. The fire resistance limit of a beam with central prop is determined by the sign of loss of bearing capacity using the analytical equation (1). The use of the new proposed technological method allows to determine the actual fire resistance of a two-span reinforced concrete beam without full-scale fire impact, simplifies engineering calculations, increases the reliability of static material quality control and non-destructive testing, reduces economic costs.
In order to preserve the historical part of the city of Saratov, a survey of the building, which is an object of cultural heritage and refers to an architectural monument of federal significance, was carried out. During the inspection, defects in floor structures made of different materials and having different technical solutions were revealed. At different elevations, the supporting elements of the floors are made of wood, brick and reinforced concrete. The results of the survey with a description of the defects of wooden and stone floors. The analysis of defects allowed us to establish the causes of their appearance. Recommendations on troubleshooting are given. The described defects are characteristic of buildings of an old construction, therefore the results of this work can be used when conducting a survey of architectural monuments.
ARCHITECTURE AND CIVIL ENGINEERING
HEAT SUPPLY, VENTILATION, AIR CONDITIONING, GAS SUPPLY AND LIGHTING
The analysis of the values of the concentrations of the formed nitrogen oxides and the temperatures of the jet plume under various conditions of mixture formation is carried out. The plots of the distribution of torch temperatures and concentrations of nitric oxide in the calculated area for oxidizer temperatures of 20, 60, 100, 150, and 200 ° C were obtained and analyzed. Mathematical modeling of the gaseous fuel combustion process was carried out using the FlowVision software package. An analysis of the results showed that a decrease in the temperature of the air supplied as an oxidizing agent leads to a significant decrease in the concentration of nitrogen oxides in flue gases, while not significantly affecting the change in the flame temperature. The research results can be used to solve the problems of optimizing boiler plants, in order to reduce harmful flue gas emissions. Further modeling is planned to determine the dependence of the influence of various factors on the degree of formation of nitrogen oxides in the flue gases of boiler plants.
The influence of geometric (length, diameter and wall thickness of a unit equivalent channel of the nozzle), thermophysical (density and heat capacity of the nozzle material) and operating parameters (air flow through the regenerator and the time of one stage of accumulation / regeneration of thermal energy) on the thermal efficiency of stationary switching regenerative heat exchangers was studied . It was revealed that by varying the length and diameter of the channel and air flow, it is possible to increase thermal efficiency up to 10%. It was found that the wall thickness of a single channel, the density and heat capacity of the material of the nozzle, as well as the time of one stage, slightly aff ect the thermal efficiency of the regenerative heat exchanger.
A comparative analysis of explicit solutions of the Colebrook-White equation is carried out. The median values of relative deviations, coefficients of determination and computational complexities for each approximation were obtained. The results of the iterative solution of the Colebrook-White equation by successive substitution method were used as the intrinsic solution. Approximations by B. Eck and A.R. Vatankhah were identified as the most effective in terms of computational complexity. It was shown that widely used approximations by P.R.H. Blasius, A.D. Altshul and J. Nikuradze although simple, provide acceptable accuracy only within restricted ranges of Reynolds and relative roughness.
ARCHITECTURE AND CIVIL ENGINEERING
WATER SUPPLY, SEWAGE, CONSTRUCTION SYSTEMS FOR PROTECTION OF WATER RESOURCES
The calculations of the rain drainage system, which provides the collection of surface runoff from the interscholastic stadium, including a football field with artificial turf, running tracks, tribune, were performed. The optimal tracing of the system is designed, the best materials and storage capacity are selected. The assessment of the qualitative composition of collected effluents and the direction of their further utilization was carried out. Options of detailing of nodes of a shower drainage system according to different engineering and geological conditions of the territory of the Astrakhan region are considered: subsidence of soils, fl ooding by underground waters. The developed model, based on the principles of optimization and import substitution, allows to apply it as a model on the territory of the arid regions of the South of the country.
The article analyzes the relationship of the system of technical regulation in construction and regulatory relations for the provision of public services. Changes in the current system of legal regulation in the sphere of water supply of apartment buildings are considered. The article shows that the subject of rationing belongs to several areas of regulation, which requires improvement of the methodological basis for the design of in-house systems of hot and cold water supply of an apartment building and the creation of legitimate methodological tools. Recommendations on the formation of methodological procedures, the implementation of which will provide the legal legitimacy of the methods of hydraulic calculation. The method of determining the calculated (limit) costs of cold and hot water in centralized systems of drinking water supply of an apartment building.
The article studied modern cleaning methods and technological schemes of enterprises of the fat-and-oil industry. Based on literary sources, the effi ciency of wastewater treatment by physicochemical treatment methods has been investigated. Reagent pretreatment of wastewater is widely used, and research focuses on the selection of optimal reagents and doses. A modern method for the treatment of fat and oil containing wastewater is biomembrane technology. Classic treatment schemes are often unable to achieve regulatory requirements for the quality of treated wastewater; therefore, the use of membrane bioreactor technology may be in demand for treating food wastewater. The problems of using various methods of purifi cation of fat-and- oilt wastewater are identifi ed. The economic effi ciency of the proposed cleaning methods is determined.
The results of studying the process of electrocoagulation processing of joint oil-emulsion and chromium-containing wastewaters, which are formed at metal-working enterprises, are presented. Objective: to optimize the process of electrochemical neutralization of a joint effluent stream containing emulsified oil products and hexavalent chromium ions, and to study the composition and structure of sludge. Data were obtained on the study of the properties and composition of the sludge formed during the electrical treatment of a joint effluent containing emulsified oil products and hexavalent chromium ions to develop a disposal technology using thermogravimetric and x-ray phase analyzes. The results of the research during the planning of the experiment made it possible to determine the optimal regimes by pH and contact time.
ARCHITECTURE AND CIVIL ENGINEERING
TECHNOLOGY AND ORGANIZATION OF CONSTRUCTION
A version of the project for the installation of the spatial structure of the coating of an industrial building was developed. The technological feature of the project was the presence of cramped working conditions. The feasibility study of the methods of assembly and installation of the coating, taking into account the peculiarities of the construction of the coating, the features of the construction site and the needs for lifting machines, showed the eff ectiveness of the installation of the coating with enlarged blocks assembled on the ground. Mounting the unit using a traverse allowed to reduce the estimated height of the hook and select a crane that does not diff er in the high cost of rent. It became possible to apply the adopted installation scheme provided that an individual design of the beam was developed. The calculation and design of the traverse itself was performed, as well as the calculation of the enlarged unit for the installation situation.
ARCHITECTURE AND CIVIL ENGINEERING
THEORY AND HISTORY OF ARCHITECTURE, RESTORATION AND RECONSTRUCTION OF ARCHITECTURAL HERITAGE
The great interest of modern scientific society in architectural bionics is due to the significant practical orientation of this science, which studies the principles of construction and functioning of biological systems, primarily with the aim of creating new bionic objects whose characteristics would be as perfect and highly effective as in living systems. Architectural-bionic practice gave rise to unusual forms, suitable in a functional and utilitarian sense. The architectural bionics family can offer a lot of cereals, which have the property of elasticity and resistance to bending and fracture with a few materials. In wheat, as in a number of other grain crops, the strength of the stem is determined by a set of features of the anatomical structure. The structure of the article reveals the concept of sustainable architecture, referring to antiquity. The basis of the study is a bionic object displayed in the form of a stalk of wheat, the properties of which allow wheat to undergo atmospheric influences under the existing load of ears, which greatly exceeds the own weight of the straw. The properties of the elasticity of the stem of the wheat are examined through the Young’s modulus (E), which provides resistance to lodging. In the experimental part, an explanation is given of the mechanical strength of the wheat stalk, characteristic of most cereals, due to: height, diameter of the stem, their ratio, the thickness of the walls of the straw, the development of mechanical tissues. For an illustrative example, the predominant properties of the stalk of wheat, the calculations of the relative volume using standard materials in the construction industry of uplifting buildings and structures are given.
The urban planning history of Samara and the features of the formation of its planning structure are considered. The main historical periods in the history of the development of the city are revealed. The structural features of the pre-regular, regular city are considered, the main historical areas are investigated. The role of urban squares in modern Samara is analyzed. Based on the definition of the term architectural dominant, several main classifications of architectural dominants are given, and Samara’s historical dominants are identified. The role of the main architectural dominants in the formation of the urban environment, historical and modern, and the transformation of this role with the growth and development of the city are examined in detail. The influence of later development on the historical dominants of the city is revealed.
In the research the morphology of the geological structure, the genesis of a natural object, embedded in such a “construction” as time, are studied. As a result of the loss of historical and informative artifacts of the environment, the territory loses its identity. In order to maintain the structural basis, a scientific study of the genesis of the object is carried out. The existing problems of modeling objects in conditions of disturbed landscapes are considered. The concept of historical genetic reconstruction method is introduced. A paradigm of research and modeling of the territory and objects that have lost their natural, aesthetic and cultural essence, based on formal features and is an imperative of design, is proposed. For this purpose, elements of the operating base are being developed.
ARCHITECTURE AND CIVIL ENGINEERING
URBAN PLANNING, PLANNING OF RURAL SETTLEMENTS
Green construction is a new fundamental environmental direction in the design, construction, operation and dismantling of buildings. Currently, there are two international systems for assessing the eco-efficiency of construction: BREEAM (British system) and LEED (American system). BREEM is a scientific standard focused on a large number of environmental issues. LEED is a commercial standard for energy consumption. The above assessment systems have different levels of minimum requirements; buildings that meet these requirements receive respectively a BREEM certificate or a LEED certificate. The article discusses buildings certified according to different systems for assessing eco-efficiency, located both in the Russian Federation and in the world. The leading place in the number of “green” buildings in Russia belongs to the city of Sochi, thanks to the 2014 Olympics. Then, there are the capital cities of Moscow and St. Petersburg, on the territory of which are located not only shopping, entertainment and office “green” buildings, but also residential eco quarters. Sports arenas were built for the 2018 FIFA World Cup in host cities. In particular, the Samara 45-thousandth sports arena became the first Russian facility for the 2018 football championship, which won international recognition, having received a certificate according to the standard of the BREEM system.
The methodological scheme of the sequence of actions and the implementation of methods for evaluation of city transport hubs potential to create a universal environment is revealed. The social aspect is to improve the quality of transport services for the population, taking into account the organization of movement of citizens groups with limited mobility: the creation of comfortable conditions, the possibility of planning time, saving money, expanding the geography of trips and the choice of ways to make them. The considered requirements and recommendations for the design of a universal environment on pedestrian communications in transport hubs were the result of a comprehensive analysis of the existing experience and features of the organization of pedestrian communications in transport hubs of the metropolis.
The choice of the type of natural lighting in architectural and construction practice depends on a number of constructive, technological and engineering measures. The authors’ analysis of Russian and foreign experience in the design and construction of buildings allows us to ascertain the fact of a stereotypical approach to providing premises with sunlight and the lack of interest in actively developing technical means that can improve lighting. The article is devoted to the organization and improvement of the quality of lighting in buildings for various purposes. The paper generalizes the types of natural lighting used in modern buildings. The positive and negative sides of all types of lighting are analyzed and recommendations are given on the possibility of their use for buildings with “difficult to light” spaces. The parameters that influence the choice of options for lighting with sunlight are highlighted depending on the functional purpose of the building and its planning structure.
The problem of forming open public spaces of the residential areas from the perspective of sustainable development is viewed. This approach is considered in the study in social, economic and environmental areas with the aim of creating investment interest, individualization of the territory, concentration of activity of residents and favorable living conditions. The territory of interest to various professional, social, amateur groups of residents requires a rational approach to its use, the structuring of space.
The article presents a comparative analysis of the main characteristics of planning elements “quarter” and “microdistrict”, identifies their significant differences; provides an analysis of the development of approaches to the construction of residential areas in Russia in terms of creating a comfortable urban environment for human life; reveals the advantages of modern quarter as a planning element of residential development.
Two projects of the Linear City, which appeared at the beginning of the 20th century, in the United States, regardless of the project implemented earlier in Spain by Arturo Soria, are described. The technical and town-planning features of the Roadtown project by Edgar Chembless and the social ideas underlying it are given. The reasons for the failure of this project, as well as similar projects that appeared later, are analyzed. The history of the project of Milo Hastings and his idea of a linear concentration of dwellings in the city are given. Although this project was also not implemented, the reasons why its town-planning ideas found application in the post-war construction of the American suburb and social ideas in the New Deal of President Franklin Roosevelt are shown.
ELECTRIC POWER STATIONS, NETWORKS, AND GRIDS
In order to optimize energy consumption at the design stage and fine-tuning the main components of the gas distribution mechanism, calculations were performed. The method of calculating annular gaps was used to select the rational dimensions of the pusher assembly design, as well as the gas distribution mechanism of the engine of construction machines. A pusher model is considered in the design scheme of the engine lubrication system for construction vehicles, which helps to refine the calculated data on the oil consumption of the main consumers. The data obtained accelerate the development of the engine design at the design, development and operation stages of machines and mechanisms. The main task was to calculate the pusher of the indicated type to obtain data on oil consumption through the annular gap formed by the sleeve and the pusher body.
INDUSTRIAL THERMAL POWER
The object of study in this article is presented in the form of an inertial-vacuum dust collector (IVDC). There are two types of IVDC: first generation and second generation. The first experiment was conducted in 2009, and the second in 2018. The plants consider similar principles of dust collection. The purpose of this article is to compare the results of a full-scale experiment conducted on a second-generation inertia-vacuum dust collector at the Omsk TPP-4 station and the data of a numerical experiment calculated in ANSYS CFX. After the initial calculations, adjustments were made to the boundary conditions. The data obtained in the course of a numerical experiment with specified boundary conditions are in good agreement with the full-scale experiment. Measurement schemes and graphical dependences of the degree of capture efficiency on the geometric characteristics of the ash collector are presented.