Vestnik MGSU

Introduction. The article discusses the results of field tests of composite I-beam beam made of pultrusion fiberglass profiles (PSP) to assess their bearing capacity and deflections. The relevance of the study is due to the limited use of solid beams made of pultrusion fiberglass profiles for relatively large spans, which requires the use of composite beams. Constructive solutions have been developed for beams of composite I-section made of pultrusion fiberglass profiles, the belts of which are made of paired corners, with solid and perforated walls. Currently, there is no current regulatory documentation at the level of codes of practice or GOST, which provides a method for calculating the bearing capacity for composite sections made of PSP, especially beams with a perforated wall.Materials and methods. Experimental studies were performed on a three-point bend. During the field tests, vertical movements of the beams and wall deformations relative to the shelves were recorded.Results. According to the results of field tests, the bearing capacity, deflections, and composite I-beams with solid and perforated walls were determined. A comparative analysis with the results of experimental and numerical studies has been carried out.Conclusions. The significance of field tests is to assess the bearing capacity and deflections, beams of composite I-section made of pultrusion fiberglass profiles with three-point bending, the possibility of further development and improvement of their calculation methods.

Introduction. A modification of the theory of composite rods (TCR) by A.R. Rzhanitsyn is proposed. It is one of the most common methods for calculating multilayer building structures. The stress-strain state of multilayer composite beams is determined by the functions of deflections, bending moments and forces in continuously distributed interlayer connections that prevent mutual shear of the layers. The forces in the shear connections are determined by solving a system of n ordinary differential equations of the second order, where n is the number of interlayer seams. The proposed method is based on the hypothesis of a functional relationship between the shear forces in the beam seams. This assumption allows us to reduce the problem of determining the functions of shear forces to solving one ordinary differential equation of the second order. Thus, the number of simultaneously solved differential equations describing the problem is reduced from n + 2 to three for any number of layers.Materials and methods. To solve the system of differential equations, both in Rzhanitsyn’s formulation and in a simplified formulation, difference equations of the method of successive approximations (MSA) are used.Results. The results of calculation of a six-layer beam using three models are obtained: in the formulation of A.R. Rzhanitsyn, with the involvement of the simplified method of R.F. Gabbasov and V.V. Filatov, in the formulation of the authors of the paper. The results of calculation by simplified methods with TCR are compared. The influence of various parameters (geometric and mechanical characteristics of layers, shear stiffness of seams) on the operation of simplified models is studied. Diagrams of maximum longitudinal and tangential stresses are constructed for different options for the layout of the cross section of a composite beamConclusions. Recommendations are presented and limitations on the possibilities of using the proposed calculation method for multilayer beams under static loads are described. The method can be recommended for use in the practice of design organizations and in the educational process of specialized higher education institutions.

Introduction. The results of research of metallurgical slags characteristics are presented, the possibility of their application in organomineral mixtures for pavement base layers is considered, taking into account technological features of their preparation and indicators of operational properties. The research topic is relevant both for individual regions and for the country as a whole. The amount of waste from metallurgical production increases annually and is estimated in hundreds of millions of tons. The main direction of reducing production waste is their disposal. This problem is becoming even more urgent against the background of constantly decreasing reserves of natural materials, the increase in demand for which is due to the high rates of development of material production and the acceleration of scientific and technological progress. Thus, the use of slag materials in road construction will not only contribute to waste disposal, but will also solve a number of environmental and economic problems. The aim of the research is a comprehensive study of the influence of ferrous metallurgy slags on the physical, mechanical and operational properties of organomineral mixtures of pavement base layers and substantiation of their effective application in road construction. To achieve this goal, it is necessary to perform the following tasks: 1) to determine the chemical analysis of the studied slags and to study the mechanism of interaction of slag materials with binders; 2) to assess the degree of influence of slag materials on the physical, mechanical and operational properties of organomineral mixtures; 3) to develop a methodology for determining the accumulation of residual deformations in organomineral mixtures and to establish patterns of their change over time; 4) to determine the modulus of stiffness and the number of cycles to failure in the studied organomineral mixtures, depending on the nature of the origin of the material. Steelmaking slags of ferrous metallurgy can contribute to the production of organomineral mixtures with increased physical, mechanical and operational properties due to the increased content of calcium compounds, microporous additions of the crystal structure and active hydration processes, which can have a beneficial effect on the durability of the structural layer of the pavement when used.Materials and methods. All materials used in this study were subjected to tests to determine their physical and mechanical parameters, and materials representing industrial by-products were additionally subjected to chemical analysis. This approach made it possible to assess the compliance of inert materials with the requirements imposed in the Russian Federation for starting materials for their use in organomineral mixtures, and to identify critical characteristics of materials that can affect the strength and performance properties. The use of waste from the metallurgical industry has a number of advantages over conventional natural materials, including low economic and environmental costs. Converter and blast furnace slags of various granulometry were used as waste products of the metallurgical industry. An X-ray fluorescence test was performed to assess the chemical composition of steelmaking slags. The sulfur content was determined on an elemental analyzer by burning a specimen at a temperature of 1350 °C. Carbon content was determined on a total organic carbon analyzer by burning a specimen at a temperature of 950 °C. The analysis of other components was carried out on an atomic emission spectrometer with inductively coupled plasma after decomposition of the specimen with a mixture of inorganic acids. To select the compositions of organomineral mixtures based on a complex binder, studies were carried out to study the nature of the interaction of an organic binder with slags. To assess the effectiveness of the use of the studied slag materials, optimal compositions of organomineral mixtures were selected in accordance with GOST 30491–2012, from which cylindrical specimens were made and tested for indicators of physical and mechanical properties, as well as plate specimens and beam specimens for performance properties. During the experimental studies, a universal device for compression and bending testing, Unifame 70-TO108E, and a test press were used. The degree of stability of specimens from organomineral mixtures to the accumulation of residual deformations was assessed using a dynamic testing device (patent No. RU 152287 U1), in accordance with the test procedure developed for this purpose. To assess the performance parameters in terms of modulus of rigidity and the number of cycles to failure and water resistance, the test methodology used to assess the quality of asphalt concrete properties was adapted, taking into account the technological conditions characteristic of organomineral mixtures. For these purposes, the CRT-RC-H2 device was used, simulating the operation of a roller, and the CRT-SA4PT-BB device, which is a servo-pneumatic system that supplies a sinusoidal load with constant deformation and frequency to the specimen beam.Research results. The chemical and elemental composition of slag materials is analyzed, on the basis of which the main directions of the possibility of using metallurgical industry waste in the road industry are determined. The mechanism of interaction of slag gravel and sand with binders was studied. It was established that the use of steelmaking slags makes it possible to increase the strength and performance properties of organomineral mixtures. Test conditions were developed and a method for evaluating the water resistance of specimens from an organomineral mixture according to the tensile strength under indirect tension and resistance to the accumulation of residual deformations was tested. A method for assessing the stability of organomineral mixtures to the accumulation of residual deformations on a dynamic test device is proposed and the dependence of the change in the indicator over time is established. According to the results of experimental studies, the expediency, economic and environmental efficiency of using waste from the metallurgical industry in the layers of the base of the pavement structure was confirmed.Conclusions. A chemical analysis of steelmaking slags was performed, their positive sides were noted and the mechanism of their interaction with binders was studied. Steelmaking slags of ferrous metallurgy made it possible to obtain organomineral mixtures with increased physical, mechanical and operational properties relative to similar mixtures of natural mineral materials. For the first time, within the framework of experimental studies, the actual values of operational properties were obtained in terms of “residual deformations”, “modulus of rigidity” and “number of cycles to failure” in organomineral mixtures of natural and slag materials, which can be used in making design decisions. The use of organomineral mixtures of slag materials in the base layers slows down the accumulation of residual deformations by 30–35 % relative to similar mixtures of natural mineral materials, which makes it possible to extend the service life of the structural layer of the pavement.

Introduction. Peculiarities of design of the hydrotransport system, which is part of the technological chain of ore processing are considered. A critical analysis of the characteristics of the slurry pipeline of the tailing facility of the mining and processing complex “Ryabinovy” (MPC “Ryabinovy”), located near the city of Aldan, was carried out.Materials and methods. In the hydraulic calculations of two-phase flows, the initial data were the chemical composition of the tailings, the basic features of the processing plant, and the geodetic data of the place of tailing storage. Based on the theory of two-phase flows, the authors provide calculations of the characteristics of solid particles, flow and energy losses necessary for the design of slurry pipelines. The engineering tasks of calculating two-phase flows are the calculation of head losses during the hydrotransportation of various materials through slurry pipes, the determination of the maximum velocity at which the transported material is not yet deposited to the bottom of the flow and the choice of equipment for hydraulic transport. The dependence of specific energy losses of two-phase flows, at average velocity, below those recommended by regulations on the basis of experimental data obtained at the Department of “Hydraulics and Hydrotechnical Engineering”, NRU MGSU, is given. Solid particles transport is possible if the flow has sufficient energy for this without sediment formation at the bottom of the pipeline. The average speed corresponding to the sediment-free transport mode is the critical velocity of the two-phase flow.Results. The recommendation on the choice of an effective mode of hydrotransport is based on the principle of minimizing energy losses. The deficit of flow energy in the slurry pipeline is revealed and the necessity to use the criterion on the need to exceed the average velocity over the critical velocity of the two-phase flow is shown.Conclusions. The necessity of using the speed reserve coefficient to achieve an effective mode of transportation was formulated. Particular attention is paid to the calculation of head losses at a critical transport speed, which is the basis for the choice of pumping equipment.

Introduction. Installations for thermal energy storage make it possible to smooth peak loads and provide stability of heat and power system. These solutions are of particular relevance for private households. The purpose of this paper is to analyze the feasibility of using a heat accumulator based on talc-magnesite and with aerogel thermal insulation.Materials and methods. In order to determine the temperature on the insulation surface and visualize the temperature profile, simulation in the ANSYS software package was carried out. Autodesk Inventor was selected as an automatic design system.Results. Images of temperature profiles were obtained at 350 °C for thermal insulation thicknesses: 20 and 50 mm for aerogel, 70 and 150 mm for mineral wool. The analysis showed that for all options the surface temperature remained below 60 °C, which indicates the correct choice of insulation thickness. For the thermal insulation option made of mineral wool (150 mm) and aerogel (50 mm), the surface temperature turned out to be significantly lower than necessary, which made it possible to reduce the thickness of the insulation layer to 70 mm for mineral wool and 20 mm for aerogel, respectively. The results obtained allow us to conclude that the use of aerogel-based thermal insulation can significantly reduce the thickness of the heat-insulating layer.Conclusions. Despite the complexity and high cost of creating thermal insulating materials based on aerogel, its use as part of a thermal accumulator will help avoid many problems associated with aging, destruction and frequent replacement of thermal insulation, reduce the load on thermal insulation structures and significantly increase the economic efficiency of thermal power systems, reducing losses during production and transfer of thermal energy.

Introduction. The concentration of population and economic activity in agglomerations is primarily due to comfortable living conditions and developed infrastructure. At the same time, the issues of housing development in recent years have gone beyond the discussion of the problems of development of the construction industry and have become the subject of spatial development research. Housing stock and infrastructure facilities in the periphery do not correspond to demographic and migration processes. Thus, there is a need to develop analytical tools capable of planning a balanced infrastructure of the region.Materials and methods. Two research methods were used to investigate the set tasks: 1) studying the dynamics of key indicators of the region’s development; 2) calculation of the value of indices reflecting the concentration of the studied indicator (Herfindahl – Hirschman index — for the volume of housing construction, population concentration and the number of jobs; concentration coefficient of economic activity indicators).Results. The analysis of the main factors has shown that the long-term growth of the share of the population older than working age occurs in parallel with the growth of the population younger than working age. This imbalance is certainly the achievement of the state’s priorities in the field of improving the quality of life of the population through the introduction of social support measures for elderly citizens and young families. In agglomerations, jobs are technological and productivity is higher. Residence in the metropolitan area is considered not only as a place of work but also as a comfortable place to live.Discussion and Conclusion. The study of the regions of the Republic of Tatarstan allowed to show a complex situation with spatial development of the region — concentration in agglomerations and destruction on the periphery. In this regard, the study of agglomeration processes should become one of the elements of the national regional policy.

Introduction. Any development can be affected by two phenomena of convergence and divergence. Convergence is the process of convergence of the levels of development of systems (economic, social, anthropotechnical) over time, and the opposite process is called divergence. These phenomena are mainly caused by the processes of globalization and scientific and technological progress. The classification of types of convergence is provided and their definitions are given. The practical implementation of the concept of convergence is associated with theoretical constructions in relation to engineering and reengineering, which in turn determine the necessity of the formation of a new organizational and economic mechanism for investment and construction activities, which may be based on the use of dissipative organizational structures. The paper defines such structures and identifies their main properties and limitations in implementation.Materials and methods. The study used the provisions of a systematic approach, structural and functional analysis of investment and construction management, methodology of logistics of regulatory influences, as well as methods of investment design, strategic, operational management in the context of the development of the theory of life cycle management of capital construction facilities.Results. The analysis of the manifestation of convergence in the investment and construction sector is carried out, including its causes, classification and terminological identification of types of convergence are given, the influence of convergence on the reengineering of business processes and organizational structure in construction is established, and on this basis a theoretical justification is given for the use of dissipative organizational structures to ensure sustainable development.Conclusions. The phenomenon of convergence largely determines such type of activity as reengineering, which is aimed at increasing efficiency through transformation and rational construction of management processes, as well as organizational structures in the presence of dissipation of regulatory influences.