Reinforced concrete structures must have sufficient reliability throughout their entire service life. In problems related to predicting service life based on an assessment of the technical condition, reliability can be considered as the probability of failure-free operation of structures, which consists in the ability to perform the required functions under given conditions during the design life. One of the methods for solving this kind of problem is statistical methods. The beam reliability calculation was carried out. It was further assumed that the beam was subject to degradation. As a result, a graph was constructed of the dependence of reliability on the depth of corrosion penetration into the compressed concrete zone. This graph also shows how the category of the technical condition of the beam changes over time.

Keywords: reinforced concrete structure, bendable structure, prediction, service life, reliability, technical condition, degradation impact

This article considers a new type of structures in the form of lightweight stainless steel floor slabs, gives an overview of application in construction practice, discusses the advantages and disadvantages. Based on the results of a series of structural analysis of several conditional models of buildings with different structural systems, the parameters of economic efficiency in the form of reduction of total metal intensity are determined. The area with increased efficiency of application of the considered plates in buildings is defined and the vector of necessary further research on the topic is outlined.

Keywords: B-Core slabs, multilayer floor slabs, stainless steel, metal cost reduction, efficient application area, structural building layouts

Numerical methods for calculating shells provide a wide range of solutions when varying various parameters. The object of this study is a mathematical model of thin isotropic elastic shells of revolution of constant thickness. The problem is solved from the position of moment theory.To determine the stress-strain-state of the shell, the solving system is obtained by transforming the basic systems of equations of rotational shells by moment theory and the variables separation. All SSS and load components are decomposed into Fourier series along the circumferentail coordinate. A programme in the Python programming language was written to verify the numerical solution by a computer mathematics system (CMS-Maple 17). Matplotlib library was used for plotting graphs. Examples of numerical calculation of ring spherical shells for the action of ring loads are given. The variants of action of one and two ring loads on shells with different conditions of support along the contours and different half shell angles are presented. The difference between the calculation results of the two methods for bending moment functions and displacement functions is tabulated. The highest value of the difference is 0.0015%. Plots of the variation of meridional bending moment under the action of two ring loads are presented. The variants of rigid pinching along the contours and hinged support are considered. Exsmples are given for shells with the ratio of radius of curvature to shell thickness equal o R/h = 25, 50, 150, 200. Considered of the half shell angles equal to 90, 100, 130 degrees.

Keywords: rotation shell, spherical, isotropic, elastic, computer mathematics system, Python programming language

This article presents the results of simulation of the stress-strain state of the base under dies with a stepped shape of the bottom of the support. Numerical modeling was performed using Plaxis 2D. The results of modeling stamps with different angles of descent of steps with an equal surface area of ​ contact with the soil showed the dependence of stresses and displacements on this parameter.

Keywords: effective foundation, shallow foundation, columnar foundation, die with convex support surface, stepped sole, soil mechanics, settlement of foundations

The article addresses the issue of determining the ultimate eccentric compressive longitudinal force from an external load acting on a compressed reinforced concrete element. The calculation assumptions are adopted in accordance with the current code of practice SP 63.13330.2018. The transformation of the initial formulas given in this code allowed the explicit solution of the cubic equation with respect to the compressive longitudinal force without the need for iterative calculation methods. The solution thus obtained can be employed in the design process to determine the optimal section dimensions.

Keywords: reinforced concrete, excentric compression,ultimate forces

The article discusses the use of organic binders to modify the properties of cement soils. The scope of application of cement soils in construction practice, including the construction of highways, is considered. The influence of the use of organic binders as a complex additive that modifies the strength characteristics of cement soils has been studied. The influence of the use of complex modifiers and additives on the frost resistance and water permeability of cement soils has been determined.

Keywords: cement soil, organic binder, highway, working layer, frost resistance, modifiers

The article deals with the peculiarities of the results of tests carried out to determine the characteristics of the contact zone organized by stamping on a steel plate. During the test, the specimen was in the steel mold in which it was manufactured. The steel form was used to prohibit horizontal movement of the steel thin plates and minimize the effect of uneven slippage of the steel gouge in the direction perpendicular to the shear force. The considered tests were carried out according to a specially developed methodology, which took into account the specifics of the contact zone shear operation, the applied tooling and took into account the set objectives of the study.

Keywords: contact zone, contact characteristics, test methodology, shear tests, stamping, composite design

The paper deals with the problem of choosing the most rational form of spatial metallic cross-barrel coating. Mathematical models of flat structural coating, elliptical paraboloid and hyperbolic paraboloid coatings in SCAD software package based on finite element method are analyzed. Nodal connections of rod elements of coatings are taken according to the system “Kislovodsk”. The obtained parameters of stress-strain state of three different structural coverings allow us to speak about practically identical operation of the structures.

Keywords: structural covering, spatial covering, cross-bar covering, stress-strain state, “Kislovodsk” system, SCAD program complex, finite element method, hyperbolic paraboloid, elliptic paraboloid

Layered reinforced concrete beams made of multi-modulus of elasticity concretes are increasingly used in engineering practice. The step-by-step iterative method in combination with numerical integration in the calculation of such structures using a nonlinear deformation model and real deformation diagrams is a rational solution, despite the currently lack of a generally recognized approach to assessing the stress-strain state of sections of layered beams.

Keywords: double-layer reinforced concrete beams, normal cross-sections, nonlinear deformation model, high-modulus concrete, neutral axis coordinate

3d-printing is the leading direction in world advanced technologies. For today 2614 patents were displaying in the Worldwide date base. General Electric is more effective companies in patenting materials for 3d-printing.

Keywords: materials for 3d-printing, review of patents

When studying the problems of water filtration to a single horizontal imperfect drain of finite length, in a system of interacting horizontal imperfect drains, it is necessary to consider spatial (three-dimensional) filtration problems. Unlike flat (two-dimensional) problems, spatial filtering has been studied in less detail, since it is difficult to obtain rigorous solutions to their problems.

Keywords: water supply facilities, filtration, equipotentials, drainage, borehole, pressure reservoir, drain, pressure, inflow, reservoir, watercourse

The article discusses the development and evaluation of the design of a rotary-type mechanized parking system, the use of which will solve the problem of shortage of parking spaces in large cities. The paper presents the results of the research, a patent analysis was carried out, the composition of the mechanized parking system was determined and a rotor-type design was developed, an engineering analysis of the design was performed using the Autodesk Inventor software system. The calculation showed that the structure meets the requirements for strength characteristics.

Keywords: mechanized parking system, modeling, parking space, durability, static research

This article discusses several ways to determine the calculated lengths of steel columns in the plane of the frame. By analyzing existing techniques, the most successful method of selecting the calculated lengths for steel columns in a free multi-storey frame was determined. Taking into account the non-standard case of fastening crossbars to the considered section in the frame of the overpass, using the LIRA CAD PC, as well as the Crystal module (implemented in SCAD), the loss of stability of equally loaded elements in the most sensitive area is clearly shown.

Keywords: Euler's formula, loss of stability, coefficient of calculated length, calculated length, coefficient of stability margin, finite elements

The article discusses the issues of stability of pedestrian paths and staircases located on sloped areas and interacting with a complex geological environment. The features of designing construction projects on sloping areas are considered. The reasons for the occurrence of various defects and destruction on the staircase, located on the embankment of Khabarovsk, were investigated. An assessment of the stability of the structure during repair work is given. Measures are proposed to increase the stability of the structure.

Keywords: staircase, slope, slope stability, stress-strain state, fortifications

The article examines the unique symbiosis of modern technologies and national traditions, analyzes the stages of formation and development of the main directions of architecture development in the North Caucasus in the context of modern trends. The subject of the study is the architecture of the North Caucasus, taking into account modern design trends. The object of the study is buildings and structures, urban conglomerates of the North Caucasus region. The most striking example of this symbiosis is the new projects in the Caucasus, where architecture literally combines with the landscape, showing the unique interaction between man and nature. Thanks to modern construction methods, these buildings combine traditional architecture and modern construction technologies, creating a harmonious space. The architecture of the future, despite its subjectivity, has readability because culture and technological progress always affect architecture. In general, we can identify a number of features characteristic of the architecture of the future: cost-effectiveness, ergonomics, environmental friendliness and versatility. It is also necessary to mention new modern construction technologies, which include elements such as artificial intelligence, automation and robotization of processes, the use of 3D printing and digital modeling of building information (BIM).The symbiosis of modern construction and Caucasian culture is a unique combination of architecture of the past and the present. The synergy between modern construction technologies and traditional Caucasian culture can be very promising. It has the potential to simultaneously revive local cultural identity, contribute to sustainable practices, and create unique architectural designs that harmonize innovation and tradition. Historical forms and materials are actively combined with modern technology and materials, resulting in an architecture that simultaneously preserves its roots and looks to the future. This close interaction and symbiosis highlights the importance of culture in architecture and shows how innovations can be used to preserve and update cultural heritage.

Keywords: construction, architectural design, modern trends, energy efficiency, thermal protection of buildings, construction industry, ecology, green construction, architectural bionics, North Caucasus

The large-scale development of Russia's lands led to the creation of a railroad network. Along with the laying of the railroad, the entire transportation infrastructure, such as bridges, tunnels and overpasses, was erected. Many structures are already more than 100 years old. The structures are deteriorating and approaching the end of their life cycle. It is therefore necessary to reconstruct or dismantle these structures. Due to the increased freight traffic between China, Russia and Western Europe, it is necessary to reconstruct all tunnels on the BAM. This paper presents one of the tunnel reconstruction options and investigates by mathematical modeling the stress-strain state of the system "array-construction" by which the tunnel can be reconstructed.

Keywords: mathematical modeling, stress-strain state, railway tunnel, reconstruction, finite element method, drilling and blasting, mechanized tunneling, mining machine, displacements, Baikal-Amur Mainline

Lightning protection of tanks is important problem as accidents can cause catastrophic consequences for people, infrastructure and environment. In the article analysis of typical defects of steel lightning rod towers' flange connections is carried out. 16 towers built in 2000 in Novorossiysk as a part of oil tank farm were studied. Each 55-meter tall tower consists of 3 girths and 3 sections with bolted flange connections. During the analysis of technical documentation the following common defects were observed: cracks and deformations of girths near welding joints that connect them with reinforcing ribs; gaps between flanges and their radial displacement; weld leg lengths longer than allowed; presence of water, biological damage and corrosion. Reasons of said defects are analyzed. They consist of non-compliance with regulatory requirements during welding as well as insufficient attention to the thermotechnical issues. Recommendations for the repair and safe exploitation of lightning rod towers are given. The results can be used during the technical inspection of steel lattice towers with flange connections.

Keywords: bolt, bolted flange joint, defect, flange, inspection, joint, lattice tower, lightning rod, steel, steel tower

Currently, a large amount of research is devoted to the use of polymer composite materials applied for increasing the strength and durability of reinforced concrete elements. In compressed reinforced concrete columns, the bearing capacity depends on the eccentricity of the external force application and the corresponding stress-strain state, as well as on the arrangement and quantity of composite materials bonded to the surface of the structure. The choice of the arrangement scheme of composite materials depending on the stress state of the structure is of current interest for researchers. At the same time, studies conducted on centrally compressed elements often have contradictory effects. The main purpose of this study is to perform numerical experiment of a digital model for the centrally compressed concrete column reinforced with composite materials. The calculation results for 3 short columns with different reinforcement schemes are presented. It is shown that the use of composite materials to reinforce structures increases the bearing capacity up to 10%. Based on the study results, recommendations on the optimal schemes of reinforcement with composite clamps of inflexible columns reinforced in the transverse direction are proposed.

Keywords: reinforced concrete columns, normal sections, finite element modeling, reinforcement with composite materials

The organization of an enclosed space to ensure the basic processes of life (amateur professional activities, family communication, parenting, housekeeping, physiological and psychological recreation, maintaining health and hygiene) is traditionally an urgent task of architectural creativity. One of the possible solutions is the format of a low-rise (one or two floors) individual residential building, which includes several rooms (rooms) for residential and non-residential purposes, providing the necessary conditions for life processes. Low-rise individual residential buildings (with adjacent territories) are characterized by a number of advantages: a high level of living comfort, direct connection with the natural environment, the opportunity for full-fledged and versatile work and leisure, taking into account individual characteristics and preferences.

Keywords: individual residential building, composition, functional zoning, spatial relationships, living environment, efficiency, functional scheme, space, aesthetics, traditions, innovations

Research of modeling methods of steel structures's joints with the use of computer-aided engineering (CAE) systems is important, because scheme that most accurately reflects an actual state of the elements makes it possible to select their rational design. The aim of the article is to analyze an influence of modeling variations of truss joints on the stress state of a transverse frame. The object of the research is the plane frame of a two-story building with the truss made of hot-rolled steel equal leg angles. The subject of the study is the stressed state of the structure. In the article the following problems are solved: two models of the frame (with flexible and rigid truss joints) were created with the use of LIRA-SAPR CAE program, loads were calculated, results were obtained, the values ​​of bending moments and shear forces in the elements were analyzed. Conclusions were drawn about the influence of variant modeling of truss joints on the stress state of construction.

Keywords: CAE, flexible joint, joint, plane frame, rigid knot, static scheme, steel, steel angle, stress-strain state, truss

The article presents the results of the calculation of a high-rise building, the load-bearing frame of which uses wooden structures. With a significant height of the structure, wind load begins to have a significant impact on the deformability of the frame. A calculation scheme is proposed, in which two options for applying wind pressure are considered - on columns and in floor beams.

Keywords: high-rise building, permanent loads, short-term loads, instantaneous loads, modulus of elasticity, stiffness, stress, displacement, CAD

The work reflects the results of the influence of various factors on the deflections of the profiled flooring at the stage of concreting the slab. The relationship between the deflections of corrugated sheets in parts of its span and in parts of the total thickness of the slab at different heights of the design section of the slab has been established. The purpose of the work was to study the influence of various factors (the thickness of the corrugated sheet, the profile and height of the corrugations, the span of the slab) on the deflections of the profiled decking at the stage of concreting the slab, taking into account the recommendations of the standards. The work also studied the influence of the acquired deflection on the final deflections during the operation stage. The object of the study was a floor slab on profiled flooring. A calculation and analytical research method was used based on current regulatory documents. Research results. An assessment is made of the influence of corrugated sheet deflections on the applicability of various corrugated sheet spans in the range of spans from 3 to 6 m. Recommendations are proposed for limiting the maximum deflections of corrugated sheets at the stage of concreting the slab to 1/100 of the design span of corrugated sheets with a slab section height of more than 200 mm. Recommendations are given to limit the use of small thicknesses of corrugated sheets from 0.7 to 1.0 mm for spans over 3 m. Conclusions. Based on the results of the study, recommendations were developed for the use of optimal thicknesses of floor slabs on profiled flooring for various spans. Recommendations are given for limiting the thickness of the corrugated sheet depending on the span and the overall height of the slab section. The research results can be used in the design of steel-reinforced concrete floor slabs and in practical work when examining the technical condition of structures.

Keywords: concreting stage, corrugated sheet, deflection, profiled flooring, steel-reinforced concrete slab

Changes in the elastic characteristics of the soil for a base model that is inhomogeneous in depth are considered. The dependences of the modulus of elasticity of the soil and the coefficient of lateral pressure on the relative depth are obtained.

Keywords: modulus of elasticity, lateral pressure coefficient, pressure, compression curve

Engineering preparation of the territory for the construction and development of a residential complex is a difficult task. In the development area, fluctuations in the groundwater level are possible due to natural processes - flooding of the territory or during operation due to man-made processes. The work presents the results of the survey and assesses the impact of future construction on the hydrological situation of the built-up areas. Materials from engineering-geological surveys of the composition of soils in the lake water area and the building area were studied in order to determine the possibility of using alluvial soil from the lake for engineering preparation of the territory.

Keywords: engineering and geological surveys, urban development, alluvial soil, engineering preparation of the territory

The article discusses the method of constructing a horizontal protective screen made of large-diameter steel pipes used for the construction of tunnel-type structures using a closed method. The factors influencing the choice of this method are analyzed - features of the construction site, economic and time indicators. As an example, a project for constructing a protective screen made of large-diameter pipes for the construction of a two-section transport tunnel under railway tracks is considered. Diagrams are provided that provide basic information about the construction project, its main parameters are considered: geometric shape and dimensions, location of structural elements with an indication of their sizes. The sequence of construction work is presented, consisting of six main stages, starting with the construction of auxiliary working pits and ending with the construction of the internal structures of the tunnel. Such construction of tunnels in dense urban areas requires taking into account and minimizing their impact on existing structures and transport routes in the construction area. The article presents the results of numerical calculations of stabilized movements of the soil mass, confirming the effectiveness of this method.

Keywords: horizontal protective screens, tunnel-type structures, large-diameter pipes, soil deformations