bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration separation of bulk construction mixtures by measurement sizes on sieve classifiers
Authors: adiev Fail Akhm , Gizzyatov Renat , Nazipov Ilshat
Published: August 2020

The vibrational separation of bulk building mixes by size is studied using stochastic-based sieve classifiers. The system of stochastic differential equations is constructed to determine the linear density of particles on the surface of the classifier sieves. The linear density of particles on sieves is approximated by white noise, which allows the system of equations to be called stochastic. The solution of the system of stochastic differential equations with respect to the average value of a random process is determined. We construct an approximate solution for the distribution density and transition probabilities of a random process using the properties of the white noise. Knowing the density of the distribution of the number of particles on the surface of the classifier sieves determines all its characteristics of interest. The obtained solutions allow us to calculate the extraction coefficient and evaluate the efficiency of separation.
Cement concrete modified by fine-dispersed anionactive bitumen emulsion for road construction
Authors: Garipov Aidar , Makarov Dmitry , Khozin Vadim , Stepanov Sergei , Ayupov Damir
Published: August 2020

Cement concretes are strong and able to resist external adverse environmental factors, have an increased water absorption and, as a result, insufficient frost resistance and deformability. Therefore, wide use of cement concrete in road construction is limited. Modification of road cement concrete with anionactive bitumen emulsions is a current and promising solution. By introducing small concentrations of bitumen emulsions into cement concrete, one gets a material with the basic properties of cement concrete and the properties of asphalt concrete. Rigid crystallization bonds formed as a result of cement hydration are dominantly present in cement systems, while coagulation type bonds with adhesive properties bitumen prevail in asphalt systems. Depending on the quantitative relationship between these bonds, the deformability of concrete tends to change. The main technological and operational properties of the resulting road cement concrete were investigated. Cement concrete was bituminized by introducing the anionic bitumen emulsions into the concrete mixture (from 0.5% to 8.0% of cement weight), which allowed increasing technological properties of concrete mixture and the performance properties of hardened concrete. This increases mobility, improves deformability of hardened concrete, increases its abrasion resistance, water resistance, frost resistance, reduces shrinkage without reducing the strength properties of road concrete.
An additive for autoclaved aerated concrete on quick-extinguishing lime
Authors: Kuznetsova Galina , Morozova Nina
Published: August 2020

Slow-extinguishing lime is used in the production of autoclave hardening aerated concrete. If the production of aerated concrete is arranged in parallel with the production of silicate brick, then the lime will be quick-extinguishing. In this connection, the present paper considers the possibility of using quick-extinguishing lime and waste products from silicate brick. A significant content of quartz (over 75%) in the composition of silicate brick makes it possible to use it in a ground form as an analogue of ground sand. Also, the paper has established a reduction in the setting time of cement and an increase in the strength of autoclaved concrete. However, slip-like additives reduce the mobility of the mixture and increase its water demand. The deterioration of processing characteristics is observed when ground waste is introduced into the sand slurry of aerated concrete mixture. Therefore, a complex additive based on the waste of silicate brick, plasticizer and gypsum stone has been proposed, which allows for expanding the scope of application of quick-extinguishing lime, reducing the water demand of the mixture without reducing mobility and increasing the strength of the finished product.
Reengineering of manufacturing processes in the construction organization
Authors: Mavlioutov Ramil , Belyaev Mikhail , Borisova Kristina
Published: August 2020

The introduction of advanced technological solutions in modern conditions becomes a paramount problem for industrial enterprises. In relation to Russia where the digitalization of the construction industry is proclaimed, the priority of introducing of information technologies is forming a new goal for the country, the one to join the global process of a new technological revolution. This cannot be achieved without a fundamental re-planning of the key production processes of the construction enterprise. We consider this procedure as “reengineering of production processes”. An approach to assess the validity of the reengineering of production processes of a construction enterprise, implemented with the involvement of an engineering company, is presented. The benefits due to the involvement of an engineering company are given. The proposed approach allows calculating the reengineering console, which makes it possible to make an informed decision on the implementation of the reengineering project by both the enterprise and the engineering company. This study can be demanded by both potential participants in the process, and scientists who conduct research in this area.
The improvement of construction industry innovative potential through the creation of a cluster
Authors: Zagidullina Gulsina , Ivanova Rufina , Nugumanova Guzel , Sirazetdinov Rustem , Zaripova Anna
Published: August 2020

The study is devoted to the analysis of the innovative potential of enterprises in the construction industry. The creation of an effective cluster increases the country’s innovative potential, as well as the economic indicators of production activity of the construction industry enterprises. The investment and construction cluster will help to create the competitive advantages that the construction industry enterprises involved into it have. The study considers stages and principles of the investment and construction cluster formation. We propose an algorithm for assessing the innovative potential of the investment and construction cluster based on the results of a SWOT analysis. The study assesses the innovative potential of the investment and construction cluster. Based on multiple correlation and regression analysis, we developed an equation for the dependence of the gross regional product on the system of indicators characterizing the innovation activity of the investment and construction cluster.
The optimization of the number of reinforcing bars in the slabs in grasshopper and integration with TEKLA and LIRA-SAPR
Authors: Nasybullin Ranel , Akhmadiev Fail , Bakhareva Olga
Published: August 2020

The article reveals the interoperability of several software products. The concept of interoperability of software products is supported by OpenBIM standards, providing a project with a reliable platform and open source code for integrating BIM models with other environments. It is possible to exchange data between software systems, not only through the IFC format, in the article we will consider other means of information exchange. An algorithm is formed that optimizes the number of the number of reinforcing bars in the slabs. The optimization is possible due to the interaction of different software systems through plugins.
Application of catalytic destruction methods in wastewater treatment
Authors: Andreeva Svetlana
Published: August 2020

The objective of the present work is to study the process of removing wastewater pollutants of peroxide nature chemical compounds by catalytic destruction method. To achieve this the following tasks were solved: a) to study qualitative and quantitative composition of wastewater, as well as composition stability over time; b) to study the possibility of applying methods of peroxide catalytic destruction in the wastewater medium; c) to determine optimal conditions for peroxide catalytic destruction; d) to determine the possibility of such wastewater purification at biological treatment plants. As a result of the research, it was established that wastewater has a variable quantitative composition of pollutants both at the moment of their formation and over time, which significantly complicates selection of reagents for peroxide catalytic destruction. Optimal conditions for catalytic decomposition of peroxides in the wastewater medium were determined. Thermal decomposition of peroxide compounds in the presence of iron-ion catalyst-Fe(II) was studied. The proposed methods of peroxide destruction allow achieving a high degree treatment of wastewater from these components, and to use biological methods of decontamination in further post-treatment of effluents.
Determination of the main technical reasons for the fall of pile driving machine near the slope of the foundation pit
Authors: Khuziakhmetov Rustam , Nurieva Daniya
Published: August 2020

The study was conducted to determine the main technical reasons for the fall of the pile-driving machine that occurred when driving-in of piles in the immediate vicinity of the slope.

As a result, slope stability of the soil in the process of driving-in of reinforced concrete piles near the slope crest of the underlying pit was determined. The calculations were performed using the following four well-known methods: methods of Fellenius, Krey, Terzaghi, Chugayev. The loss of stability of the soil was caused by the imbalance of external and internal forces (the presence of construction equipment and stored materials near the slope and its dead load). The calculations were performed for six loadcases of the earth wall. The article presents in detail the case in which the slope collapsed.

The importance of the results for the construction industry lies in the need for a comprehensive study of safety issues at all stages of the life cycle of construction projects, starting with the preparation of a design assignment, surveys, design, construction, operation, repair, reconstruction, etc.
Analysis of the lateral stability of the pile-driver SP-49
Authors: Khuziakhmetov Rustam , Sakhapov Rustem , Zemdikhanov Minsur , Andreeva Svetlana
Published: August 2020

This study aims to exclude the possibility of pile driver capsizing due to exceeding slope of the construction site surface.

The paper determinates the reasons for the violation of the requirements of urban planning legislation and regulatory and technical documentation, which results in a pile driver capsizing. The authors calculated the center of gravity of the pile driver and its lateral stability during the preparation of piles for driving and the driving itself.

The significance of the results for the construction industry lies in the need to increase the level of safety when performing pile work and taking into account the actual conditions of the site in the places of their implementation. At the investigated construction site, the slope of the construction site did not exceed a guaranteed safe value 3°.
Pressure loss reduction in ventilation ducts by shape optimization of the removable profiled components
Authors: Malanichev Igor , Akhmadiev Fail
Published: August 2020

Reduction of pressure loss in ventilation systems can be achieved by changing the shape of the airflow region and smoothing the boundary surfaces. The installation of special profiling components inside a straight shaped part of ventilation duct is the simplest way to reduce the coefficient of local resistance and pressure loss. For the best result under given conditions, the shape optimization problem must be formulated and solved. In this paper, we use the open source code software and numerical methods to study the optimal-shaped drag reduction components in elbow ventilation ducts. Computational Fluid Dynamics is used to predict the flow fields and the drag reduction effect. After the validation of flow model against existing experimental results, a detailed study has been conducted to shape optimization of removable profiled components. The optimization problem is parameterized by a small number of structural variables, which are the coordinates of the control points of the splines that form the contours of the flow region. Total pressure loss coefficient is selected as the objective function for optimization. A genetic algorithm is used as an optimization method. The results reveal that the removable profiled drag reduction component can reduce the resistance in ducts by 60%-80%.
Solution of conjugate problem in a conical coil heat exchanger
Authors: Krutova Iraida , Zolotonosov Yakov
Published: August 2020

Today, coil heat exchangers are widely used in various industries. A large number of works have been published devoted to the study of the characteristics of helical coil heat exchangers. According to the authors, conical coil heat exchangers have higher efficiency compared to helical ones. The article investigates the influence of the geometric parameters of conical coil heat exchangers on their effectiveness. The object of study is a conical coil heat exchanger with different tube diameters of the inner coil (di = 13, 15, 17 mm) and various number of turns (N = 6, 10, 14). Modeling was carried out in the Ansys Fluent software package. For each combination of the parameters, data were obtained on the temperature and velocity of the coolant at the outlet. It was found that a change in the number of turns by a factor of 2.3 leads to an increase in the temperature of the heated fluid by an average of 9.7 ° C. The effect of changing the diameter of the inner coil is non-linear.
CFD-modeling of flow in confluence nodes of ventilation units of multi-storey buildings
Authors: Shopayeva Aiman , Safiullin Rinat
Published: August 2020

This paper considers the flow characteristics in ventilation units, which are used in natural ventilation systems of multi-storey residential buildings. Three configurations of ventilation units were considered: standard with straight walls, with a beveled wall and with a guide insert. For each configuration, three sizes of bypass hole at the confluence of flows from the satellite channel and the collection channel were considered. The problem was solved numerically using the CFD Flow3d software package.

It was established that for a ventilation unit with a straight wall in the satellite channel, the formation of separation zones that are significant in width and length at the confluence node is typical. The length and width of separation zones affecting the resistance of ventilation unit as a whole increases with the enlarging of the bypass hole size in the collection channel and decreases when using a beveled end wall, that directs the flow upstream of the exhaust air. For the considered geometries of confluence nodes of ventilation units, the relationships between local resistance coefficients and velocity (Reynolds number) in the collection channel are obtained.
Formation and motion of droplets in gas cleaning devices with porous rotating atomizers
Authors: Safiullin Rinat , Kareeva Juliya
Published: August 2020

This paper presents the study of characteristics of porous rotating nozzles recommended for use in gas cleaning devices. The influence of geometrical and technological parameters of atomizer on the size of droplets and the trajectory of their motion is investigated theoretically and experimentally.

To determine the droplet size when it is detached from the spherical granule of porous rotating atomizers (PRA), the simulation in the Flow3D program was used. A model for calculating the droplets trajectories when spraying a liquid with the help of porous rotating nozzles is compiled. The model is based on a joint solution of equations of droplet motion in a centrifugal field and evaporation of droplets.

The relationship between the volume of separating droplets and the size of granules of porous material and the geometry of atomizer is obtained. The regularities of droplet motion in cylindrical devices with porous rotating atomizers are established depending on the droplets sizes and parameters of the cross-flow. The relationship between parameters of droplets’ trajectory and their volume is recommended for calculating the geometry of the spray torch of PRA in gas cleaning devices.
Two-dimensional flow movement in the area of protective regulatory structures
Authors: Bazarov Dilshod , Norkulov Bekhzod , Vokhidov Oybek , Uljaev Farokhiddin , Ishankulov Zokhidjon
Published: August 2020

The article discusses the results of numerical studies of the flow movement with a sharp change in the parameters of the channel. Basically, the results of the study using the system of two-dimensional equations of hydrodynamics-Saint-Venant are analyzed. The divergent form of two-dimensional equations describing the movement of a water stream at a site of regulation of a channel by protective and regulatory dams is given. The influence of the length step on the results of numerical experiments is investigated numerically. Graphs of the time variation of the longitudinal velocity component behind the sudden double expansion of the channel are compiled. The flow was unsteady all the time and had the character of stationary pulsations, and the finer the grid, the richer the spectrum of these pulsations. It was noted that in numerical calculations, the time step in the calculations was always much less than the minimum pulsation period, therefore, these pulsations were not associated with difference oscillations that can arise when approximating by central differences. It is concluded that, according to the authors from the following and the present work, they collectively show that the pulsations on different grids differ significantly, the average values of the velocities are close, and thereby the solution for the average values is well converged, this shows that the pulsations are a property source equations of Saint-Venant. The applicability of the numerical model, consisting of two-dimensional shallow water equations, the vector equation of momentum conservation and the scalar equation of mass conservation, in description the flow with the presence of circulation zones, which is typical when water flows are constrained by protective-regulatory structures. In this case, the solution pulsates around a certain average value, and the average length of the circulation zone behind the sudden expansion of the open flow is in good agreement with the laboratory experiments of G.L. Mazhbits.
Oil heater with high temperature heat transfer agent
Authors: Faizov Azat , Sadykov Renat
Published: August 2020

The work is devoted to the development of a block oil heater with a capacity of 40 t/h when it is heated from 10 to 60°C. The fuel used is natural or associated petroleum gas.

As a result of the analysis of heat-technical calculations according to the aggregate characteristics, a high temperature organic heat transfer agent, thermal oil, was adopted as a secondary heat transfer agent.

A block oil heater with a thermo-oil boiler unit is designed, consisting of two modules: a heat generation module and a heat transfer module. The description and operation of the heater with a thermo-oil boiler unit is presented.

The significance of the results obtained for the construction industry lies in the fact that this heater is able to operate in heating or hot water supply mode, when the automation system is switched to the appropriate installations. The developed block oil heater, in comparison with existing analogues, has the following advantages: it has compact dimensions and high specific power, the control unit is equipped with an automated microprocessor complex, and the modular design allows it to be transported by any type of transport.
A modified design-analog method of teaching geometry and graphics as a means of integrating of training and design activities of future architects
Authors: Liudmila Danchenko , Nail Tuktamyshov
Published: August 2020

The strategy of teaching orthogonal and other projections, as well as the basics of geometry formation of the future architect is based on the practical orientation of the teaching process and is based on a modified design-analog method. Possibilities of the building industry show an urgency of research and realization of methods of shaping geometry in a course of descriptive geometry. The purpose of the study is to develop technology for the formation of design skills of shaping, based on the proposed modified design and analogue method. The object of research is geometrical and graphic training of students pursuing the degree in Architecture or Design of architectural environment. The subject of study is the technology of training of shaping in the course of descriptive geometry and based on a modified design-analog method. The characteristic feature of this method is its connection with the architectural practice of both educational and professional. The methodological basis for its application is the method of creating of the architectural form of an object. The workshop has been tested and allowed to consider a set of actions and operations, their sequence.
Territorial (re)branding as a factor in the sustainable development of the city
Authors: Ponomarev Evgeny , Ivshin Konstantin
Published: August 2020

As of this date, territorial branding is a key tool to increase the attractiveness of the territories of cities, districts, settlements. By dint of branding, the competition between territories for resources – financial, economic, labor, demographic – is intensified. Territorial branding is a marketing strategy to increase the competitiveness of cities, regions, settlements, revealing the potential of the selected territory and, thus, expanding its capabilities and creating a basis for sustainable development of a city.

Presently, the main achievement of territorial branding is to stimulate the social activity of citizens. Growing interest from different social and age groups of population to creation of an urban brand contributes to sustainable development of cities. The authors consider territorial (re)branding as a multidimensional design algorithm including architectural and design solutions as a single strategic concept. The indicated approach to the formation of a comprehensive concept is a sequence of proposed procedures performed in a certain order, according to the following requirement: predesign analysis; creation of the conceptual model of development; implementation of design documentation; the formation of a high-quality visual-perceived environment of the urban area.
Financial stimulation as factor of competitiveness rise of residential developers
Authors: Barinov Valerij , Vasil’chikova Ekaterina , Potekhin Igor
Published: August 2020

The paper deals with the analysis of scientific works about resettlement from dilapidated housing in Voronezh. Authors offered the system of financial stimulation for construction projects, which are based on government-private partnership. The financial stimulation is based on different mechanisms and its purpose is to rise influence on financial interests of participants investment-construction projects. This is solution to the problem of dilapidated housing and developer’s competitiveness rise. The solution has two instruments: first is tax stimulation and the second is rise of program efficiency by using financial resources. Preliminary evaluation has shown that algorithm of design and introduction allows achieving the following results: decrease tax load, decrease investor’s need in finance, and transparency rise and quality of finance control rise. The risk exists because non-purpose usage of developer’s income at the best case in any period leads to losing the opportunity of finalizing construction object, or in the worst case – bankruptcy. Project financing with current mechanism helps to decrease expenditures and to rise competitiveness of residential developers.
Environmental activities of a petrochemical company as a sustainable factor of the city and region
Authors: Mironova Margarita , Romanova Anna , Evgeniya Irina , Galeeva Irina , Egorov Danila , Akhmetova Alena
Published: August 2020

The paramount objective of modern society is to preserve a livable environment for generations to come. In addition to the need to restore the impaired qualities of the environment, measures also must be taken to preclude environmental disasters from happening both now and in the future. The formation of a balanced regional system of cities is hampered by the deterioration of the environmental situation and a decrease in environmental quality indicators. The concentration of industrial sites and vehicles represents one of the biggest adverse anthropogenic factors which stems from the human impact on the environment. Growing industrial clusters and the rising number of vehicles in large cities result in a critical environmental situation. Environmental monitoring measures, once introduced, will facilitate the sustainable development of urban areas and the economy of the region.
Modeling the towing properties of construction vehicles
Authors: Mukhametshina Rumiya , Makhmutov Marat
Published: August 2020

This article studies the ways to increase the towing properties of propulsors and the patency of wheeled vehicles.

The characteristics of the machines running systems significantly affect the technical level of the unit. The paper justifies the advantages of wheel dwellers over caterpillar ones. The advantages include small specific metal consumption and the possibility of usage on the roads. Wheel tractors provide the best working conditions for the driver and maintenance personnel.

Analysis of the calculated coefficients shows a significant scatter of values, which causes difficulties in the calculations. For this, it is necessary to know the values at each interaction of the tractor propulsor with the soil. The same slippage values can be obtained with different values of the coefficients. The task is simplified if these dependencies have one coefficient.

The paper obtains a model for a more complete assessment of the towing properties of wheel and tracked vehicles with a minimum number of experimental coefficients, which makes it easily applicable for engineering calculations.
Experimental studies of the working process of compaction of sand with a vibrating plate
Authors: Sakhapov Rustem , Kadyrov Adil , Gatiyatullin Mukhammat , Zemdikhanov Minsur
Published: August 2020

The paper investigates the process of compaction of a sand layer with a manual vibroplate under various technological conditions. The moisture content of the sand layer was previously determined in accordance with the accepted methodology. Then, as a result of preliminary experiments, the authors selected the limits of variation of some technological parameters of the vibroplate. To reduce the volume of experiments and increase their accuracy, the authors used an almost rotatable three-level non-factorial plan. The obtained experimental data were processed using the Statistika.exe software. As a result, the obtained mathematical models describe the dependences of the density of the sand layer on the mass of the additional load and the speed of the vibroplate, as well as on the frequency of rotation of its unbalanced shaft. The results are presented in the form of three-dimensional graphs and equations describing the compaction process. The paper analyses the research results and conclusions. They will allow to determine some optimal technological parameters of the vibroplate during the compaction of the sand layer.
The critical forces in the weak ground under the influence of technogenic relief
Authors: Burlakova A M , Malova N A , Filatov V V
Published: August 2020

The initial critical force that the ground is exposed to from the weight of a structure is one of the main characteristics of the “structure-ground environment” system. A significant part of grounds are classified as weak, and the strain modulus value does not exceed 5 MPa. These soils have a weak load-carrying capacity and they are significantly deformed by the weight of the structures and the static load of technogenic relief. The theory and methodology of determining the initial critical force and its maximal action depth for various two-dimensional technogenic land forms, the force diagrams of which are described by trapezes and triangles of various types, are considered. The models grounds considered herein are a homogeneous elastic half-space or horizontally layered strata on the surface of a homogeneous elastic half-space. The nomograms of the relations of the initial critical force and its maximum depth of action to the ground’s physical and mechanical properties are attained. The identified relations are quasi-linear and the value of the initial critical force increases with an increase in the ground’s physical and mechanical parameters. The presented nomograms significantly simplify the calculation of the initial critical force in the ground.
Analytical and numerical solution of the stress-strain state of sleeper foundations
Authors: Glushkov Alexey , Glushkov Vyacheslav , Glushkov Ilya
Published: August 2020

The article presents the results of numerical modelling of strip sleeper foundations. The analysis of the influence of the distance between the sleepers in the conditions of a two-dimensional problem. As a comparison, the results of the calculation of the analytical corner points method is presented. The results of the study of sleeper foundations with different distances between sleepers up to 3b are shown. The analytical solution shows the distribution of stress over depth when changing the size of sleepers, distances between sleepers. An analytical solution for the distribution of vertical displacements over depth is obtained. The results of the numerical solution show the components of stress and strain at different distances between sleepers, the dependence of precipitation on the applied pressure and the distance between sleepers. These studies are confirmed by the results of experiments of various authors. Designs of sleeper foundations are implemented in the construction of buildings and structures, which reduce the cost of the zero cycle, reduce the material consumption in comparison with standard solutions. The article is of interest to specialists in the field of soil mechanics, geotechnics, and foundation engineering.
Steady-state and unsteady-state moisture regime of enclosing structure
Authors: Gagarin V G , Khavanov P A , Zubarev K P
Published: August 2020

This paper describes the moisture transfer problems of enclosing structures which are crucial in modern construction industry. In terms of current condition of science, researchers do not know the moisture transfer law in capillary-porous materials, so they need to work with a variety of mathematical models. We developed the new steady-state and unsteady-state formulation of mathematical models based on moisture potential F, which takes into account water vapour and liquid movements uniformly. It is vital to understand whether we can use steady-state moisture transfer mathematical model in a design engineer work or we must use the unsteady-state one, so we make a comparison between them for a single-layer aerated concrete wall. We compare moisture behaviours of the steady-state and unsteady-state processes in two ways: comparison of the moisture distribution in the thickness of the enclosing structure during maximum moisture accumulation period and comparison of the average moisture of the wall during a year. It was found that the solution of the unsteady-state equation of moisture transfer gives significantly more possibilities than the solution of the steady-state equation of moisture transfer. As a result, we recommend to use the developing unsteady-state mathematical model to predict the moisture regime of enclosing structures.
The position of the maximum wetting plane in building enclosing structures
Authors: Gagarin V G , Khavanov P A , Zubarev K P
Published: August 2020

We investigate the maximum wetting plane position in two enclosing structures: the first enclosing structure is with aerated concrete base and mineral wool insulation, the second enclosing structure is with aerated concrete base and expanded polystyrene insulation. Two fundamentally different cases of the maximum wetting plane are obtained. For the enclosing structure with mineral wool insulation, the maximum wetting plane is located between the insulation and the external stucco. It was found that when the indoor climate parameters or thicknesses of layers change, the position of the maximum wetting plane does not change. For the enclosing structure with expanded polystyrene insulation, the maximum wetting plane is located inside the insulation layer. It was found that when the indoor climate parameters or thicknesses of layers change, the position of the maximum wetting plane also changes. In terms of application result for calculation, an enclosing structure with aerated concrete base and expanded polystyrene insulation is significantly more sensitive to climate parameters than an enclosing structure with mineral wool insulation. It becomes possible not to obtain the maximum wetting plane position in encloses with mineral wool, and to use described calculated position, therefore, it can save time of engineers during the moisture regime calculation.
Floating slab track efficiency tests in Moscow underground
Authors: Smirnov Vladimir
Published: August 2020

The article deals with field tests of a floating slab track (FST) – a railway track structure used in Moscow underground. The upper track structure to be tested was erected in 1977 and consists of a concrete track slab with embedded wooden sleepers, rails R50 with “metro” fastenings and a series of rubber isolators, that support the concrete slab and transfer all the loads down to the tunnel casing. The aim of the test is to get substantial experimental data and understand its static and dynamic behaviour in order to use in further development and verification of FST’s design models. During the test under moving trains different load parameters are acquired: dynamic vertical and horizontal forces, rail & slab deflection and acceleration at different points on the slab and tunnel casing. On the basis of this multifactorial survey, verification data is acquired and weak points of the FST are investigated.
Evaluation method of technical condition façade systems
Authors: Shubin L I , Rimshin V I , Truntov P S , Suleymanova L A
Published: August 2020

The technique of monitoring the conditions of a fçgade system as part of the scientific and technical support of construction. The building demands an increased level of responsibility. Facade systems “ZIAS-100.02” with cladding with fiber cement slabs and “ZIAS-100.02” with cladding with concrete slabs are used during the construction. Monitoring of the system is carried out in order to verify the compliance of the facade fencing with the requirements of design documentation, applicable standards and requirements, as well as to determine and evaluate the actual condition of the facade system. Selective tests of anchor dowels of sizes 10x135 and 10x100 mm used in hinged facade systems were completed as part of the monitoring. The tests were carried out after a visual inspection of the facade system structures. During the tests, the ONIKS-1.VD.050 material strength meter was used. Anchor dowels were pulled out from two types of walls. The first type of walls is made of foam concrete blocks, the second type of monolithic reinforced concrete. The results of tests for two types of walls are presented. A variant of processing the individual results of the breaking load values obtained during the testing of anchor dowels of the facade system is also shown.
Rational design solutions of ensuring the walls of tanks stability to the action of transverse loads
Authors: Mushchanov Volodymyr , Tsepliaev Maxim
Published: August 2020

The article considers the task of an integrated approach to the study of the rationality of strengthening the cylindrical walls of large volume tanks with stiffening rings under transverse loads. Based on the results of computational studies, the principles of placement and rational boundaries usage of stiffening rings for vertical cylindrical tanks of various volumes are determined. The results were obtained for ideal shells and for cases of the presence of a typical geometric wall defect in the form of the angularity of a vertical weld. To validity the reliability of the results obtained, an experimental verification of the numerical model was carried out.
Reinforcement of brick structures with carbon fiber
Authors: Gonshakov N G , Gonshakov A G , Aleksiievets I I
Published: August 2020

Based on the analysis of approaches to reinforcing the brick masonry structures, the advantages of carbon fiber as a reinforcing component are presented. Methods for calculating brick structures reinforced with carbon fiber under central and eccentric compression are proposed. These methods allow determining the longitudinal force taking into account the calculated compressive resistance of the masonry, the masonry working conditions and the influence of long-term load, as well as the coefficient of the masonry surface reinforcement at the reinforced wall. The schemes of strengthening the wall with vertical canvases and at the same time vertical and horizontal carbon fiber canvases are considered. Depending on the direction of the eccentricity of the load application, methods for calculating the strength of reinforced masonry under the action of a moment in the masonry plane and from the wall are developed. The ultimate deformations of carbon fiber are estimated taking into account possible options for the destruction of masonry reinforcing elements.
The effectiveness of structures combined from elements of various materials united by bonds consistent with the SSS of the connected elements
Authors: Shmidt Alexander B
Published: August 2020

Various constructions are considered, combined over sections from various structural materials, such as engineered wood (solid, glued, reinforced, plywood, LVL, CLT, etc.), metal of various grades and alloys, concrete, reinforced concrete, fiber-reinforced concrete, etc., which are combined with the help of various elements (connections) in terms of material, form and work. Examples of various composite structures in which structural elements are connected by bonds of different types are given. The analysis of the pairing of elements of such combined (or composite) structures shows that the most effective structures are those in which the connecting elements are adaptively (self-adapted) aligned with the stress-strain state (SSS) of the mating elements. Following this rule (principle) will allow you to avoid mistakes in the design of combined structures, choose reliable and effective means of connecting structural elements. The same can be attributed to the elements of amplification or reconstruction. A brief description of the patented design with adapted connections installed in two mutually perpendicular planes is given.
Strength and deformations of high-strength concrete under short-term heating conditions up to + 90°C
Authors: Korsun V I , Khon K , Ha V Q , Baranov A O
Published: August 2020

The results of experimental researches of short-term heating effect up to +90°C on strength, modulus of elasticity and ultimate strains under axial compression of modified high-strength concrete of C70÷C90 classes were presented. The concrete was obtained with the modifier application MB 10-50C. Temperatures of tests − +20°C; +50°C; +70°C; +90°C. Lifting speed of temperature during heating − 15°C/h. The decrease of concrete strength under axial compression was installed in short-term heating conditions up to +50°C; +70°C; +90°C respectively 20%, 23%, 28% by comparison with tests at the normal temperature. Meanwhile, the modulus of elasticity decreased 18%, 20% and 22% respectively. The ultimate compressive strain of concrete increased 15%, 9%, 11% respectively at the same temperatures. This work was carried out within the frameworks of the grant of FNI Ministry of construction of Russia and RAASN on the topic 7.4.15-18 «Fundamental scientific researches of the elevated temperatures’ influence up to 200°C on the characteristics of physical-mechanical and rheological properties of modified high-strength concrete of C70÷C90 classes».
The calculation of creep deformation of high-strength concrete in relation to the conditions of exposure to elevated temperatures
Authors: Korsun Vladimir , Shvets George
Published: August 2020

The results of generalization and analysis of experimental research data on the creep deformation of heavy concretes of medium and high strength under conditions of elevated temperatures up to + 200°C are presented. It is shown that the experimental data of some authors are difficult to compare due to the significant influence of differences in test methods. All other things being equal, modern high-strength modified concrete is characterized by lower creep deformations in comparison with ordinary medium-strength concrete. It is shown that the ultimate values of the specific creep deformation of high-strength concrete at a long compression level of ήσ=0.5 under conditions of heating to 200°C are lower, on average, by 45% in comparison with similar characteristics for ordinary concrete of medium strength. With an increase in the level of long-term compression from ήσ=0.2 to ήσ=0.5, the specific creep strain of ordinary concrete of medium strength increases in the temperature range from +20°C to +200°C on average, by 28%, and in high-strength concrete with an increase in the level of long-term compression with ήσ=0.3 to ήσ=0.6, an increase in the similar characteristic was about 40%. The specific creep strain of high-strength concrete at a long compression level of ήσ=0.5 with an increase in the heating temperature from +20°C to +200°C increases by 2.8 times, and for medium-strength concrete − by 3.1 times. The massiveness of the samples (scale factor) can be taken into account using a parameter such as the modulus of the open surface. With an increase in the modulus of the open surface with a decrease in the mass of the samples, the creep strains of high-strength concrete increase at all heating temperatures. In relation to simplified engineering calculation methods, the recommended values of creep coefficients for concrete of classes B60 – B90 are proposed. In the development of concrete deformation models, approximating expressions have been developed that allow reliably assessing the creep strains of high-strength concrete of classes up to B90. The method relationships are based on the theory of aging and take into account the influence of the heating temperature, the duration of its action, the influence of the nonlinear component of creep, and the scale factor. The temperature and duration of heating before and after application of the load are taken into account using the functions of the reduced time. Satisfactory compliance of the calculated values of creep deformation of high-strength concrete with experimental data is shown.
Dynamic additional loading of the frame of a multi-story building after the failure of one of the structures
Authors: Fedorova N V , Vu N T , Iliushchenko T A
Published: August 2020

A calculated model of a building frame fragment is presented for calculating the dynamic additional loading of structural elements in the zone of possible local destruction after the failure of one of the structures. To model such a fragment, a substructure isolated from a structural system of the building frame was used in the form of a two-span statically indeterminate continuous beam under various boundary conditions on the extreme supports, loaded with a specified design load. The sudden removal of the middle supporting column of the substructure is modelled by reducing to zero for some short-time the internal force in this column, obtained when calculating the entire frame of the building. The use of level calculated schemes and analytical description of the movement of reinforced concrete substructure with variable stiffness due to cracking for determining the dynamic additional loading of frame elements of a multi-story building after the failure of one of the structures allows to define the parameters of the dynamic response of the substructure and simulate in more detail the zones of possible local destruction of the building under the considered special action. The developed algorithm for calculating physically and structurally nonlinear reinforced concrete systems can be used for the calculated analysis of the frame of multi-story buildings when designing their protection against progressive collapse.
Force resistance of steel columns of industrial buildings with corrosion damage
Authors: Buzalo N , Gontarenko I , Chernikhovski B
Published: August 2020

It is proposed to use the computer modeling results to assess the degree of operational suitability and the possibility of further safe operation of building metal structures of industrial buildings and structures that have received corrosion damage, and to predict their reliability at various stages. The force resistance of steel eccentrically compressed columns, taking into account corrosion wear, was determined in SCAD PCS using a linear model of universal finite elements for shell calculation, as well as taking into account physical and geometric nonlinearity in ANSYS PCS. The authors obtained isofields and isolines of various components of displacements and stresses for the linear model, isofields of main stresses per Mises-Hencky, and displacements for the model, taking into account changes in the elastic material modulus with increasing stresses beyond the limits of proportionality. Verification of the computer modeling results for compliance with reality was performed through an experiment. To perform the study, it is possible to evaluate the power resistance eccentrically compressed structures subject to corrosion, to determine the influence of corrosion factors and the locations of elements on the bearing capacity, to give recommendations on ensuring the reliability of the operational characteristics of structures when diagnosing the technical condition of buildings.
Mathematical modeling of transition processes due to a change in gas consumption at the ends of the inclined section of the gas pipeline
Authors: Khujaev I , Shodmonova G , Mamadaliyev X , Aminov X
Published: August 2020

The paper presents a solution to the problem of the gas-dynamic state of an elementary section of a gas pipeline with variable input and output mass gas outflows, which is obtained by the method of separation of variables. The quasi-one-dimensional mathematical model of pipeline transport of real gas takes into account factors such as friction, gravity and the local component of the inertia of the gas. By introducing the mass flow rate and averaging the velocity in the quadratic law of resistance, the autonomous equations of the telegraph equation with respect to pressure and mass flow are compiled from a system of equations. Taking into account possible abrupt changes of the unknowns in time and distance, the solution is sought in the form of functional series. The demonstrativeness of this method lies in the fact that the perturbation frequencies relevant to the parabolic and hyperbolic types of equations and the intermediate variant are distinguished. A description is given of a general method for solving the problem when temporary changes in the gas mass flow rate are set at the ends of the section. The exact solutions of mass flow rate and hydrostatic pressure are obtained for the case of a spasmodic change in mass flow rate at the boundaries of the site with a constant slope from the horizon. Numerical results related to the case of instantaneous closure of the output section of a linear section are presented. The results of the work are useful for assessing the energy intensity and reliability of gas pipelines in conditions of large diameters, high working pressures, and also when the gas pipeline is laid along a relief line.