Atmospheric air is the most important life-supporting natural environment that has developed during the evolution of the Earth. The results of environmental studies, both in Russia and abroad, indicate that pollution of the surface atmosphere is the most powerful, constantly acting factor of impact on humans, the food chain and the environment. In this regard, the urgency of the deterioration of the ecology of the surface environment in modern cities has increased disproportionately. The development of modern cities, caused by the need to improve the living environment, contributes to the creation of new buildings and structures, the development of transport and engineering infrastructure. As a result, the density of urban development and the congestion of transport networks increase, which leads to environmental pollution and complicates the ecological situation in cities. The article analyzes the ecology of the largest cities in Russia using the example of the city of St. Petersburg and assesses the aerodynamics of urban space. Convective flows occurring in the urban space are identified as one of the important factors in improving the ecology of the urban environment. The analysis of such factors as harmful emissions from vehicles and disturbed due to dense development of air exchange in urban areas, affecting the ecology of urban space.

Keywords: ecology, aerodynamics, air exchange, air pollution, transport infrastructure, high-rise building, urban development, aeration, energy consumption

The condition of a metal cylindrical mesh shell with external horizontal trusses is investigated. The basic principles of forming the structure are considered, taking into account the use of a support rib to align the faces of a mesh surface. The analysis of important force factors and deformation parameters of the reinforced shell is carried out taking into account all possible combinations of loads. The regularities of the system operation are determined and the influence of the location of the support trusses on the behavior of the structure is estimated. Vulnerable areas with maximum longitudinal forces in the elements and the greatest displacements of nodes were identified. An increase in stiffness outside the shell plane in the transverse direction was obtained and a positive redistribution of forces over the surface was recorded. An acceptable result was established from the point of view of ensuring the stability of the structure and the increased resistance of the shell to deformation was noted.

Keywords: cylindrical mesh shell, side elements, horizontal trusses, design parameters, forces, displacements

The paper presents the results of a study aimed at selecting a safe depth of an underground collector. In the scientific and normative literature there are no specific recommendations for the depth of tunneling through the existing highways. There are only recommendations for tunneling through railway embankments. Purpose of this study: scientifically substantiated recommendations for the use of reinforced concrete pipes as collector cases. The decision of problems for achievement of the objective will be carried out by means of numerical experiment - a method of finite elements.

Keywords: reinforced concrete case, underground collector, safe depth, mathematical modeling, case structures, highway, closed method of work, trenchless laying, finite element method, subsidence trough

The issues of optimization of ribbed reinforced concrete slabs with prestressing of reinforcement, taking into account geometric, strength and cost indicators, are considered. The study was car-ried out on the basis of an analysis of the sales market for building materials, the basics of rein-forced concrete resistance and the provisions of regulatory documents, design activities in the Russian Federation, as well as the works of domestic and foreign scientists. The research method is structural-analytical analysis taking into account the relationships of the factors under study. Analytical and graphic materials are presented, revealing the regularities between the geometric dimensions and the cost of components. The proposed method for determining the efficiency of a structure, taking into account the cost indicators of materials, indicates the feasibility of its ap-plication in design practice. Recommendations for design are given to ensure that structures of the minimum cost are obtained and that meet the requirements of strength and durability.

Keywords: reinforced concrete, strength, structure, reinforcement, diameter, price, cost, efficiency, dimen-sions, analysis, element

Over the past two years, during the pandemic, there has been an increased interest of the population in suburban real estate. However, there are a number of problems that a potential buyer faces. The main thing is to indicate the need for transformations, to propose solutions for the further development of the segment of individual houses, the concept of an affordable and comfortable modern village.

Keywords: mortgage, frame house, modern village, individual housing construction, configurator, infrastructure, modern construction technologies, Barnhouse

The use of metal structures as load-bearing elements of building frames is incredibly extensive. They are used in all areas, from the construction of bridges to the construction of airports and other equally important facilities. Based on this, it is necessary to design such structures extremely accurately, take into account all possible effects on the elements of the building and lay the necessary safety margins. In turn, fire, as one of the extraordinary loads, must be investigated in all its aspects. From the study of the development of a fire, to the structural analysis of elements exposed to fire. This article is devoted to determining the fire resistance of steel beams by two approaches - analytical and numerical, as well as comparing the results. After testing the beam with two methods, it was concluded that the maximum value of the deflection rate in the analysis is 32.6 mm/min, which exceeds the limit value. Since only one limit condition is exceeded, the beam is considered to meet the R30 fire resistance requirement. To increase the fire resistance of the structure, it is necessary to apply various methods of protecting the beam section.

Keywords: metal structures, load-bearing element, extreme load, structural analysis, fire impact, fire resistance

The article presents the results of comparative tests of samples of connections of wooden elements from glued wood on metal linings using screwed and glued screws, 3 samples of each of 5 types of connections (one glueless and four varieties of glued screwed connection). It has been established that the use of epoxy adhesives increases the strength characteristics of the adhesive-free joint by the criterion of breaking load by 1.46, 1.78, 1.70, 1.59 times, by the criterion of the elastic work of the joint by 1.56, 1.56, 1.82, 1.30 times for glued joints (ED-20 + PEPA, ED -20 + THETA, DER-331 + PEPA, DER-331 + THETA) respectively. Of the glued-in samples, the deformation Dult=2mm was achieved only by samples No. 8 (ED-20 + TETA) and No. 14 (DER-331 + TETA) at loads 1.77, 1.40 times greater than the load in a glueless joint. Full deformations Dp at the same load within the limits of elastic work of joints decrease by 7, 10.61, 10.61 times for glued joints (ED-20 + PEPA, ED-20 + TETA, DER-331 + PEPA), respectively. For samples of compounds (DER-331 + TETA) with a compared load value, the deformations are equal to 0.

Keywords: glued wood, metal linings, testing of joint samples, bearing capacity of the joint, deformability of the joint, upper limit of the elastic work region (URL), total deformation, permanent deformation, elastic deformation, safety factor

The article provides a comparative assessment of the possibilities of visual and machine sorting of sawn timber. It is noted that in conditions of depletion of forest resources, visual sorting of sawn timber according to the criteria of GOST 8486 cannot guarantee strength indicators corresponding to the assigned type of wood. while machine sorting allows for an objective sorting of wood according to the normalized values ​​of strength, modulus of elasticity and density, according to the specified lower limits of their standard values. Using the example of the second grade wood (strength class C24), the influence of the statistical scatter of data on the rejection minimum assigned during machine sorting of sawn timber is considered.

Keywords: timber, sawn timber, visual sorting, machine sorting, rejection minimum, standard resistance, strength classes, coefficient of variation, strength control

Studies of a cylindrical mesh shell using the method of decomposition into flat faces and the LIRA application software package have been carried out. The assessment of the possibility of using the considered approaches in the analysis of specific sites and in the case of a complete study of the mesh surface is carried out. The necessary indicators of inclusion in the work of the design, reliability, accuracy and speed of calculation of design parameters are determined. The characteristics of the stress-strain state of the system are revealed, which made it possible to recommend an approximate calculation method for quickly determining preliminary results. Methods of obtaining calculated data in all zones of the shell on a cylindrical surface are analyzed. With the help of application software, a high degree of information about the forces, displacements and mass of the spatial structure was obtained. The simplicity and clarity of visualization of the obtained schemes in accordance with the design requirements are noted.

Keywords: cylindrical mesh shell, approximate method, computer approach, calculated parameters, forces, displacements, mass

The article discusses the main indicators of acceptance of work on engineering and geological surveys for compliance with the technical task of the Customer, the main technical indicators and on the results of control and acceptance of work satisfy the requirements of the joint venture. The main indicators of the deformation characteristics of the soil obtained by static and field tests are shown. To control the homogeneity and humidity of the soil after testing, samples were selected. According to the results of the test, graphs of the precipitation of the stamp of the pressure stamp are constructed. According to the test results, modules are deformed soil deformation in a water-saturated state. Geological and engineering and geological processes are identified at the site of the designed construction and are presented with increased seismicity and flooding.

Keywords: Acceptance of work, engineering and geological surveys, customer's technical task, main technical indicators, control and acceptance of work

This article presents the results of a study of the tendency of composites based on magnesium oxychloride cements to deformation changes. The dependence of the degree of deformation of light magnesian concretes on the conditions of their hardening has been determined. The main factors influencing the deformation of light magnesia concretes have been established. The influence of hardening conditions on the intensity of deformation changes is shown. Revealed the reasons causing uneven deformation of light magnesia concrete. A method for the manufacture of light magnesia concretes has been determined, which prevents their uneven deformation and subsequent violation of the geometry of the structure. It has been established that the introduction of modifier additives, such as cellulose ethers, helps to reduce the delamination of concrete magnesia mixtures, improve their homogeneity and reduce the unevenness of deformation changes over the sample volume.

Keywords: magnesium oxychloride cement, volumetric deformations, shrinkage, expansion, warpage, hardening conditions

The article considers the problem of the formation of urban heat islands. The reasons for the occurrence of such heat islands are revealed. The influence of artificial urbanized surfaces on the albedo value is analyzed. The connection of the appearance of urban heat islands with the reduction of plant and water resources of the city has been established. The estimation of anthropogenic heat emissions, urban morphology is given. Possible solutions for reducing the influence of urban heat island on the microclimate of urbanized space are presented. A number of natural urban planning and architectural construction tools and methods of regulating urban heat islands are formulated. Their complex accounting at the stage of city planning and design of buildings and structures is indicated. This approach is recommended using software systems modeling an urbanized environment as a basis for regulating heat islands, reducing their negative impact on urban space.

Keywords: wind, urban ecology, heat island, anthropo-loading, urbanization, city, relief, albedo, pollution, environment

The article discusses the improvement of overhead power line supports (OHPL) by optimizing them and automating the design, including the creation of a OHPL design model as a single system and an algorithm for solving it. Performed the stress-strain state analysis and the optimization of structural forms of support poles, taking into account the requirements of efficiency and manufacturability. Created a system of automated one-stage design of overhead transmission line supports.

Keywords: overhead power line, optimal design, lattice support, design model

The article describes the main technological features of strengthening subsidence soils by cementation. The features of quality control of work on strengthening arrays of subsidence soils by cementation are considered. On the example of a multi-storey residential building exposed to uneven deformations, the reasons for the violation of technologies during the strengthening of the foundation soils are analyzed. The results of laboratory and field tests of soils are analyzed as part of a re-examination of the foundations fixed by the cementation method during the construction of a multi-apartment three-section residential building. The actual results of laboratory tests are compared with the values set by the project. The diagrams of the location of pits near the building are given. The photos show the presence of cement veins. The causes of uneven deformations of the newly erected object have been established based on the results of a laboratory study of the fixed subsidence soil. It is noted that strict quality control of work on strengthening subsidence soils will allow avoiding emergency consequences during the construction and operation of buildings in the future.

Keywords: cementation of soils, subsidence soil, artificial strengthening of soils, injection, geocomposite, armoelement, drilling, testing of soils, construction control

Reducing the consumption of heat resources in construction and housing and communal services is one of the key tasks solved by design engineers. The increase in the thermal protection of buildings is determined by regulatory documents, but construction customers often require it to be strengthened without any feasibility study. The objective of the study is to develop a graphical-analytical model, the analysis of which allows you to choose the most optimal combination of heat resistances of the coating (walls) and translucent structures of a particular building object.

Keywords: energy-saving project, thermal protection of buildings, "indifference" curves, the method of the fastest descent

With the increasing depletion of forest resources in buildings of normal and reduced class of responsibility for wooden structures belonging to the 2nd and 3rd classes of functional purpose, the possibility of using round timber and sawn timber from soft deciduous species such as aspen and poplar should be considered. since aspen ranks second in terms of area of ​​growth among deciduous species and is found almost throughout the entire territory of the Russian Federation. An assessment of the properties of soft deciduous wood is carried out for use in building structures that perceive power effects. The data on the percentage of lignin and cellulose in coniferous and soft deciduous wood are given. The main physical and mechanical characteristics of soft deciduous wood, the calculated resistance of soft deciduous wood for the main types of stress state are presented. The results of a comparative calculation of interfloor structures made of coniferous and soft deciduous wood are presented. It is shown that the use of soft hardwood for building structures will contribute to the expansion of the range of wooden elements against the background of the development of expensive and labor-intensive in the manufacture of glued wooden structures.

Keywords: round timber, sawn timber, soft deciduous wood, physical and mechanical characteristics of wood, design resistance, flexural modulus

This article is devoted to the actual problem of using curvilinear. stained glass facades of buildings in a modern urban environment. Stained glass glazing of radial facades of buildings is one of the characteristic elements of modern architecture due to significant advantages, such as reducing wind and climatic load on the building, environmental friendliness, energy efficiency, improving microclimate parameters, increasing artistic and compositional attractiveness, etc. The article considers a set of tasks, the solution of which will allow eliminating the negative consequences of the use of curved translucent structures in the outer shell of the building by taking maximum account of technological climatic, physical and aesthetic factors in the design of modern glazing systems for high-rise buildings with curved facades.

Keywords: translucent enclosing structures, radius facades, climatic load, high-rise buildings, glass unit lensing, focusing, urban environment, energy saving, environmental friendliness

Flexible structures typically have low flexible stiffness and a low material damping factor. Mild excitation can result in damaging high amplitude vibration and long recovery times. This can lead to fatigue, instability and poor performance. Vibration control of flexible structures is an important issue in many engineering applications, especially for precise performance in aerospace systems, satellites, flexible arms, etc.

Keywords: natural frequency, flexible stiffness, vibration, Langrange's equation, Euler's method, damping force, beam theory

The factors identified in this article, affecting the increase in the rate of monolithic construction of multi-storey buildings and structures in the winter. Organizational and technical solutions have been established, which must be taken into account when developing organizational and technological documentation. The object of the research in this article is the process of erection of residential monolithic buildings in winter by the high-speed method, the subject of the research is the organizational and technical parameters that affect the speed and quality of construction processes. The practical significance of this work lies in the fact that the results of the study can be used for the rational organization of construction production by its participants.

Keywords: monolithic construction, winter concreting, organizational and technological solutions, high-speed monolithic construction, organizational and technological potential

The article presents dependencies between deformation characteristics of SFRC with a high-strength cement-sand matrix from the type of steel fiber and its volumetric content. It was found that the introduction of fiber imparts plasticity to the matrix. Plasticity depends more on the type of fiber than on its amount per unit volume. Full deformation diagrams of steel fiber reinforced concrete have a descending branch, in contrast to the matrix diagram. The introduction of steel fiber increases the deformations corresponding to the ultimate tensile strength by no more than 75%. Deformations of the descending branch of the diagram, depend on the type of fiber, characterizing the plastic properties of steel fiber reinforced concrete. At the same time, it essential how fiber ensures the adhesion to the matrix: along its entire length due to its fiber profile or due to the design features of the anchors at its ends.

Keywords: axial tension, complete diagram of deformation of steel fiber reinforced concrete, type of fiber, percentage of fiber reinforcement, ductility, residual strength