The article considers the problem of sediment formation, sludge and corrosion on the heat transfer surface during the operation of heat exchange equipment at housing and communal services facilities. A new method of non-selective mechanical cleaning using a water hammer is proposed. The description and principle of operation of this cleaning system at the central heating station of the Ogarev Moscow State University are given. To confirm the effectiveness of the proposed technical solution, the results of thermal and hydraulic tests are presented.

Keywords: deposits, sludge, corrosion, cleaning, heat exchanger, water hammer, heat transfer

As of today, in Vietnam, to ensure stability and improve the quality of asphalt concrete, the main focus is on the application of new technologies, materials, or the improvement of design methods. However, despite significant achievements in this area, the issue of automating the processes of asphalt concrete mixture production management remains insufficiently researched and implemented. Based on the experience accumulated in Russia, the authors propose developing a system of adaptive control for the asphalt concrete mixture recipe, which contributes to the stabilization and improvement of production quality. In the article, the authors present the structure of the control system and its algorithms, as well as describe the results of modeling and evaluating the effectiveness of this system. The study shows that the adaptive control system for the asphalt concrete mixture recipe, developed based on the experience from Russia, successfully demonstrates its effectiveness in the conditions of Vietnam.

Keywords: asphalt concrete, asphalt concrete mix, Marshall stability, control system, formulation, simulation model, modeling, MATLAB, management efficiency

As part of the work on the PhD thesis on the creation of new systems and calculation devices for the design of reinforced concrete tanks for the storage of liquefied natural gas, work was done to determine the properties of concrete mixtures used in the construction of tanks in Vietnam, namely in the Hanoi area. A feature of the materials used for the manufacture of concrete is the use of local rocks, which have distinctive properties, which affects the strength and deformation properties of concrete. The article presents the results of experimental studies of the properties of concretes made with Vietnamese materials. A relationship was established between the modulus of elasticity of concrete and its prismatic compressive strength. As part of the study, 16 formulas of concrete mixtures on different materials from Vietnam were compiled and studied. As a result of the conducted research, the dependence of the modulus of elasticity and the intended strength of concrete was revealed, which will later be used in the creation of calculation devices for the design of reinforced concrete structures.

Keywords: concrete, reinforced concrete, materials, structures, modulus of elasticity, prismatic strength of concrete, deformations

In the conditions of dense urban development, the lack of parking spaces becomes a serious problem that requires a comprehensive approach to solve. It is the construction of new multi-level car parks that makes it possible to increase the number of parking spaces in a limited space. The foundation plays a critical role in the construction of multi-level car parks, as it must ensure the stability and safety of the entire structure. There are many aspects to consider when designing and constructing the foundation that help ensure the reliability and durability of the multi-level car park, which is especially important to prevent potential problems and accidents in the future. The article discusses in detail the technology of laying a pile-based foundation for the construction of a multi-storey car park located in Moscow.

Keywords: multi-level car park, rostver foundation, geodetic control, reinforced concrete beams, excavation pit

The article presents a way to increase the load-bearing capacity of a reinforced concrete column due to metal clips from the corners with an increase in the load on it. To ensure the joint operation of the existing column and the metal cage, the corners are subjected to prestressing, which is achieved by compressing the corners with jacks.

Keywords: reinforced concrete column, column reinforcement, metal cage, prestressing of the cage

Concrete paving slabs for road construction are made from mixtures consisting of hydraulic binder, fine and coarse aggregates and water. The prepared mixture of a given humidity is subjected to vibration molding under the following technological conditions: process duration 5–10 seconds, vibration frequency 30–50 Hz and pressure 70–80 kg/cm2. Hardening of freshly molded samples is carried out in a heat and humidity treatment chamber. It has been established that it is possible to replace natural coarse aggregate with fractionated scrap concrete. The compressive strength of concrete with aggregate based on recycled crushed stone is 300 - 400 kg/cm2, water absorption 4.8 - 6.2%, frost resistance F2 200 - 300. The proposed technology allows solving both economic and environmental issues for regions with large amounts of concrete scrap at temporary industrial waste storage sites.

Keywords: concrete mixture, vibroforming, modifiers, filler, waste, concrete scrap, strength

The presence of a large number of undeveloped areas within the city - now inactive enterprises - creates a negative impact on the urban environment. Since these territories are depressed spaces, the design of new residential areas with characteristic high-rise buildings seems to be a logical path for the development of the city. However, uncontrolled urbanization and dense multi-storey buildings represent a fundamental change in the human environment. The consequences of this approach lead to a deterioration in the air exchange of areas and contributes to the formation of “heat islands” that affect air pollution. This contributes to the deterioration of the environmental and social situation and the emergence of a negative perception of the environment among the population. The worsening of this problem may cause a deterioration in the social climate in large cities. The article analyzes the impact of dense high-rise buildings on the environment located on the territory of non-operating enterprises. Methods for solving this problem are indicated. The results of field observations and studies of the interhouse space are presented, on the basis of which the role of convective flows of thermal origin in the air exchange of urban space is revealed. A comparative analysis of projects for the development of the territory of a former house-building plant with complexes for various functional purposes is presented.

Keywords: urban area, air exchange, convective flows, temperature conditions, standard buildings, renovation, leisure facilities, depressed spaces

The practical significance associated with the development of automated software systems for calculating joints of steel structures of buildings and structures is noted. Using the IDEA Statica software package as an example, the calculation and analysis of the operation of a steel unit connecting the lower chord of a truss to a column was carried out. The order and sequence of entering the initial data for calculating the connection is shown. The calculation results present in tabular and graphical forms the equivalent stresses and plastic deformations of the main elements, as well as the results of inspections of bolted and welded connections of these elements to each other. A comparative analysis of numerical and analytical calculations was performed. Conclusions are formulated based on the results presented in the article.

Keywords: calculation model, connections, steel structures, component finite element method, design, nonlinear analysis, work analysis, stress, plastic deformation, bolted connection, welded connection

The article considers ecological and landscape features on the example of modern realized objects of wine tourism in the South of Russia. Based on the analysis of a number of new winery facilities and publications on this issue, some features in the context of modern architecture and its enotourism component are identified. Conclusions are made about the conformity of these features to the global modern trends in the design of buildings, such as environmental friendliness and resource conservation, respect for the landscape. On the example of the considered objects the hypothesis that the techniques of architect's work with the environment in conjunction with the original architecture increase the tourist attractiveness of wine production in general is confirmed.

Keywords: architecture, winery, enotourism, agritourism, landscape, project, landscaping, volume and planning solutions

The cases of uneven compression of a concrete cylinder in the case of simple loading and comprehensive uneven compression of a spiral-reinforced concrete cylinder under disproportionate loading are considered. The dependences of longitudinal, transverse and volumetric deformations on longitudinal stress are obtained.

Keywords: longitudinal stress, circumferential stress, longitudinal deformation, circumferential deformation, spiral reinforced concrete strut, shear strain intensity, shear stress intensity

The main means of seismic protection for increasing the seismic resistance of buildings and structures are described. The main problems associated with the design of special seismic protection equipment are outlined. The basic requirements for the design and calculations of steel frame frames taking into account seismic impact in accordance with the current design standards in the Russian Federation are analyzed. There is an insufficient description of the requirements specified in the standards for performing calculations and design of structures and their connections. Recommendations and instructions are given for taking into account the requirements of the standards for the design of steel frame frames. Schematic diagrams of special units for coupling columns with crossbars, necessary for design in seismically hazardous areas, are presented. Conclusions are formulated.

Keywords: special units, columns, beams, seismic impact, seismic protection, steel frames, plastic hinges, excess strength factor, forces, plastic moment, design.

This article presents a new developed calculation methodology, which includes provisions for standard calculations and takes into account the peculiarities of the operation of eccentrically compressed reinforced concrete structures operating at large eccentricities of load application. Adjustments have been made to the calculation methodology to take into account the following factors: the standard methodology uses the maximum tensile strength of reinforcement; proposals have been developed to determine the actual resistance of tensile reinforcement, which, in fact, will be significantly lower than the limit. Proposals are given that take into account the limiting deformations of concrete, which, in turn, will be a key quantity for determining the resistance of tensile reinforcement in the cross section. The article also presents the results of experimental studies of a flexible reinforced concrete pillar operating with a load eccentricity equal to e0 = 0.32h. Theoretical calculations and experimental studies were analyzed and appropriate conclusions were drawn.A formula has been developed to determine the real resistance of the stretched metal reinforcement at the time preceding destruction. The calculation algorithm has been compiled. When comparing theoretical and experimental strength, the difference did not exceed 5%.

Keywords: steel, heavy concrete, reinforced concrete, testing, stand

The structural integrity of many reinforced concrete structures can be broken due to corrosion of reinforcing steel. This phenomenon is quite pronounced in infrastructure where de-icing chemicals are widely used. The aim of this study is to examine the bond characteristics between reinforcing steel and surrounding concrete to evaluate its effect in corrosion. The strength of the bond was studied in terms of elongation load response, cracking behavior.It is shown that the friction between concrete and reinforcement along the edge of the rib prevents the concrete key from sliding relative to the rib. The force due to friction between the reinforcement and concrete at the rib is vectorially added to the cohesion component acting perpendicular to the rib. If friction between the concrete and reinforcement is lost, the only component of bond strength is the force acting perpendicular to the rib. In pullout failure, the friction between concrete and reinforcement is less important than in spalling failure.

Keywords: reinforcement, concrete, bond, slip, sliding, pullout, corrosion, concrete deformation.

One of the main causes of structural failure is fatigue, which is caused by failure under repeated cyclic load. The vibration strength of welded joints depends on the height of the weld catheter, equivalent Mises stresses and general movements of frame assemblies of building metal structures experiencing multi-cycle loading reliability of frame assemblies when they are reinforced.

Keywords: reinforcements, reliability, assemblies, metal structures, multi-cycle fatigue

Increasing the energy efficiency of the construction process involves the use of materials with the lowest material intensity, including thickness, as well as with a reduced content of Portland cement clinker while maintaining or improving the technical characteristics of the products. In this regard, the use of textile concrete products, including concrete sheets, is promising. The development of a composite binder containing components that reduce nega-tive pressure in hardening concrete, and consequently shrinkage deformations and cracking, made it possible to obtain products with the following waterproofness indicators: determined by the ""wet spot"" method: 1.2 MPa; with a filtration coefficient of 5-7×10-11 cm / s; the concrete waterproof grade W12

Keywords: textile-concrete, concrete web, water resistance, shrinkage during hardening, cracking, fine concrete

This article discusses the results of studies of the behavior of reinforced concrete slabs during punching. The parameters affecting the shear strength of the joints of columns and slabs are considered. Studies of the influence of the strength of concrete, the location of reinforcement, the reinforcement coefficient, the shape and size of the column are given. Various types of reinforcement of reinforced concrete slabs in the punching zone are presented.

Keywords: floor slab, column, punching, shear, bending, transverse reinforcement, dowel action

The article provides an overview of the characteristic defects that occur during winter concreting as a result of violations of the technology of concrete work. The relevance of this topic is justified by the large-scale increase in the volume of construction of monolithic buildings for various purposes: residential, public, as well as various types of structures made of monolithic reinforced concrete. A feature of the review of these defects is in this case their main causes, which are associated with violations of concreting technology due to the need in some cases to accelerate production work. The defects presented in this article were identified based on the analysis of accounting documentation when performing visual surveys in the process of scientific and technical support for the construction of buildings of increased responsibility. The violations described in the article were observed at various monolithic construction sites within modern megacities. The article describes the main causes of these defects. The ways of eliminating these defects based on engineering practice are proposed.

Keywords: inspection of building structures, defects of monolithic structures, scientific and technical support of construction, flaw detection of building structures, concreting in winter

In most countries of the world, the construction industry is one of the main sources of air pollution in urban areas and agglomerations. One of the most dangerous pollutants are fine dust particles PM2.5 and PM10, formed from the production of dusty construction processes. Due to the optimal location of administrative facilities on the construction site, it is possible to reduce the concentration of dust emissions of particles PM2.5 and PM10. In addition, the cost of the dust control method is of concern to contractors, as it leads to an increase in the cost of construction. Therefore, reducing overall transportation costs is another optimization goal. To solve several tasks at once, the study uses multi-purpose optimization using the particle swarm method (MRF) algorithm to find an optimized construction site layout that can simultaneously reduce both the level of pollution from dust emissions and transportation costs.

Keywords: environmental safety, environmental monitoring, atmospheric air protection, ecology in construction, dust suppression, feasibility study, dust collection systems, labor protection in construction

We have considered the improvement of analytical formulas for the determination of bending moments in a single-span beam with semi-rigid nodes. We have obtained analytical relationships for deflections, angles of rotation, bending moments and shear forces in a single-span beam with semi-rigid nodes. A convenient coefficient from 0 to 1 is used to specify the intermediate stiffness node. The coefficient characterizes the fraction of possible rotation of the support node. When we derived the formulas, we used the assumption of constant bending stiffness of the beam along its length and linear deformation of the beam material under load. We did not consider the cases of loading the beam with concentrated forces and concentrated bending moments in the span. We realize the complexity and necessity of calculating beams with semi-rigid nodes, so we have created a table for easy calculation. In the table you will find the values of the supporting moments depending on the degree of possible angle rotation. With the information about the bearing moments, you can load the hinged beam with them and construct a bending moment diagram. The upper left and lower left values from the table are used to determine the bending moments at the supports. The upper right and lower right values of the table are used to determine the bending moments in the beam span.

Keywords: semi-rigid nodes, multilayer structures, calculation methods, contact zone, wooden beams, reinforcement, wood, reinforcement, environmental friendliness

Ensuring the reliability and safety of load-bearing structures, buildings and structures is the most important task. The reliability or safety of a structural system is inextricably linked with the elements of this system that provide strength and spatial stability. The importance of each load-bearing element in the building system in ensuring overall mechanical safety is assessed differently. For multi-storey frame buildings, load-bearing elements, for example, columns of the lower floors, if they fail, can lead to a significantly greater volume of destruction compared to the structures of the upper floors. The article provides a methodology for determining criteria by which the level of responsibility of columns can be established depending on their location in the building plan, developed on the basis of numerical studies. As a result, a classification was compiled according to the level of responsibility of the columns of a monolithic multi-story frame building.

Keywords: limit state method, special limit state, emergency design situation, responsibility of load-bearing elements, reinforced concrete columns

The article discusses the key problems of resource and damageability of crane beams over a long period of operation. A classification of the most dangerous defects in crane beams is proposed, taking into account not only the location of the defect, but also the mechanism of its development, as well as possible causes of its occurrence. The focus is on the effect of periodic loading on the initiation and growth of fatigue cracks. The article analyzes international research in order to identify methods and methodologies used to ensure the safety and reliable operation of the objects under study. It is shown that special attention should be paid to periodic examination for the purpose of early detection of cracks of various etiologies and timely adoption of the necessary measures. It has been revealed that the most effective approach to ensuring reliable and safe operation of the object under study throughout its life cycle is the collaboration of modern calculation methods, including fracture mechanics, and experimental techniques during periodic inspections, which will allow the crane beam zones to be ranked according to the likelihood of a defect occurring and reduce risk of sudden brittle failure.

Keywords: crane beam, crack, brittle fracture, fracture mechanics, shear deformation, normal separation, finite element method, ranking by fracture risk, maintenance, stress-strain state

The article provides the results of the calculation of a steel span structure. Two options for the design scheme were considered. In scheme №. 1.1, the bending moment is perceived by the beam elements. In scheme №. 1.2, the bending moment is perceived jointly by the beam elements and cable structures. A comparison was made of the results of determining bending moments.

Keywords: main beam, secondary beam, column, boundary conditions, loads, bending moment, CAD

This article is devoted to the analysis of factors influencing the energy efficiency of high-rise buildings. Using the example of the Aquamarine residential complex in the city of Vladivostok, an analysis of high-rise buildings was carried out, calculations were performed, and the results were presented in the form of graphs that reflect the dynamics of the speed of wind flows and temperature changes in the outside air along the height of the building. Changes in these parameters increase the intensity of heat loss, which must be taken into account when developing a space-planning solution and thermal protection of the facades of high-rise buildings.

Keywords: energy efficiency, aerodynamics, air exchange, heat resistance, high-rise building, microclimate, urban development, energy consumption

The paper considers the problem of automatic detection of defects in the geometric parameters of steel ropes of elevator systems using computer vision methods. The features of flaw detection of moving steel ropes based on video sequences are analyzed, associated with the fragmentation of the image of some defects in adjacent frames and the variability of the geometric dimensions of the rope and the characteristics of the defect visible by the camera due to vibrations of the rope during movement. Taking into account the considered features, two algorithms have been proposed: to determine the defect of thickening/thinning of the rope diameter and the defect of undulation. The paper presents the results of experimental testing of algorithms on a special test bench and calculates the reliability indicators of defect detection by the proposed algorithms in the form of precision and recall of detection of each defect individually, as well as the average precision and recall of detection of both considered defects of geometric parameters of the rope as a whole.

Keywords: steel rope defects, instrumental control, non-contact flaw detection, computer vision

The problem of safety in the construction of buildings and structures has always been and remains very relevant. In our time of actively developing scientific and technological progress, new risk factors of a technogenic nature appear. Studying the survivability of buildings, and consequently the resistance of buildings to progressive collapses, is a very important task. This article examines the influence of the compliance of nodal connections of a metal frame on progressive collapse.

Keywords: progressive collapse, yielding of nodes, metal structures, survivability, special effects, calculation methods