Suspended ceilings constructions can improve the sound insulation of air and impact noise in civil buildings. To minimize the volume of the room, two types of suspended acoustic ceilings are most often used. They are: with the attachment of the structural shell of the ceiling close to the floor slab, and at a low suspension height. The influence of the slab's surface density on the correction to the sound insulation, which is created by the suspended ceiling, both in the first and in the second type, is considered. A method for a correction calculation for the sound insulation due to a suspended ceiling in these cases is given. At a minimum height the method is based on taking into account acoustic power's radiation coefficient of the shell. While for the low suspension height the method deals with the vibration's transmission from the floor slab to the ceiling's shell through the air layer and through the metal fasteners, that in this case become acoustic bridges. As a result, the formula of frequency response for sound pressure lowering, due to the sustained ceiling structure, is obtained. The influence of plasterboard suspended ceiling's perforation on the sound insulation of the entire floor structure is evaluated.

Keywords: suspended ceiling, impact noise isolation, airborne noise isolation, acoustic radiation power, limit frequency, acoustic bridge, acoustic impedance, vibration velocity level, porous and fibrous material, perforated plasterboard

The article presents a method for determining the dynamic characteristics (period and form of natural vibrations) of buildings and structures, taking into account the flexibility of the foundation under seismic impact. This also takes into account the uneven settlement during the construction of structures on various soils. The total displacement of the mass of the structure under seismic effects, taking into account the compliance of the base, is recorded as the sum of displacements from shear and rotation. In addition, a coefficient is introduced into the calculation, which is the mode of vibration of a rigidly embedded system. The formulas obtained can be used to create a mathematical model of the joint work of the "foundation - structure" system.

Keywords: structure, dynamics, natural oscillations, oscillation period, oscillation shape, base pliability, seismic impact

In connection with new trends in design and construction, customers and expertise began to introduce new requirements for engineering and geological surveys. The article discusses the main indicators of acceptance of works on engineering and geological surveys for compliance with the customer's technical specifications, the main technical indicators and results of control and acceptance of works that meet the requirements of the joint venture and receive a positive expert opinion. It is indicated what characteristics of deformation characteristics, in the presence of specific soils, must be obtained by static and field tests. Shown is the sampling of soil to control the homogeneity and conditions of the soil, after testing. Based on the test results, determine the deformation moduli of clay soils in a water-saturated state. It is concluded that modern standards in the field of engineering and geological surveys will undergo changes taking into account the requirements of global trends, implying a more detailed detailing of soil models suitable for a particular situation, which will undoubtedly entail new requirements for equipping laboratories and and to the professional skills of engineers.

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

Renovation refers to the process of improvement, reconstruction, restoration without destroying the integrity of the structure. For data collection, civil buildings located on the territory of Moscow are accepted and pass the Moscow State Examination. According to the long-term experience of passing the relevant instances, it was revealed that the Renovation Fund and the state expertise have comments on the same requirements, which encourages us to consider this stage, systematizing the comments received in order to highlight those aspects that the designer needs to pay more attention to.

Keywords: renovation, weaknesses, stages of passing the examination, systematization of comments, recommendations for reducing the time frame

The results of theoretical research and analysis of methods that will significantly reduce the weight of the gravity oil platform are presented. At the same time, its static, dynamic, and shear stability will remain under the influence of wind, wave, ice load and current load. In order to reduce the weight and overall dimensions, it is proposed to outline the lower part of the platform base with a metal sheet pile wall. As a result of theoretical studies, the dependence of the shear force under the influence of external forces acting on the platform during operation on the physical and mechanical properties of the soil and the size of the sheet pile wall is found, which will significantly reduce the weight of the platform and the cost of its construction.

Keywords: gravity oil platform, shear stability, tongue-and-groove wall, external forces acting on the platform, rollover stability

The article is devoted to the determination specificities of the actual compressive strength of the steel fiber concrete in existing buildings. The experimental studies results of an erecting mall constructions are presented. The monolithic fiber-reinforced concrete ground floor slabs were tested using three different destructive and non-destructive methods. The obtained results were analyzed. The high correlation (rdm-apo=0,855) of the steel-fiber reinforced concrete strength values obtained by the samples destruction and by the anchor pull out method was confirmed. The presented experimental studies results contribute to the statistical information accumulation on the issue of the actual strength of steel fiber reinforced concrete determination in full-scale constructions of erected buildings.

Keywords: fiber-reinforced concrete, full-scale structures, strength control, non-destructive testing methods (NDT), mechanical NDT methods, ultrasonic NDT methods

In this work, a survey of the hot water supply system from the boiler house No. 2 of Energoservice LLC was carried out. The daily schedule of hot water released for sanitary needs is given. The existing scheme of the boiler burner on-off control system is considered. A method for stabilizing the hot water preparation process by increasing the burner shut-off settings at the hour of the highest water consumption is found and described, and their values are found experimentally. A scheme has been developed, assembled and tested that allows you to adjust the operating mode of boilers at a strictly specified time of day. The proposed measure allowed us to solve the problem of selling hot water to consumers of a given quality during the maximum water intake period. In addition, the reduction in the generation of thermal energy for heating hot water at night and on weekends allowed for a 13.87% reduction in natural gas consumption in 2020.

Keywords: hot water supply, fuel consumption, pumping station, circulation line, conditional fuel, mode, boiler unit

The article discusses the natural factors that should be taken into account when designing highways. The following factors have a significant impact on the design of roads: terrain, engineering-geological and hydrogeological structure, climate, etc. The variety of natural factors is taken into account comprehensively in the design. They also take into account the negative impact of road construction on the environment. The terrain has an impact on fundamental engineering decisions, the volume of construction work, and ultimately not only on the construction cost of the highway and transport operating costs. In relation to the design of roads, there are five categories of terrain according to the complexity of road construction. Depending on the geological conditions, sometimes an extension of the highway route is used or expensive engineering measures are provided. It should be borne in mind that the use of the latest materials, road structures and new techniques for the production of construction areas is becoming less and the problems of seasonality of road reconstruction are becoming less relevant.

Keywords: highways, terrain, climate, slope, natural factors, engineering and geological process, surveys, tortuosity, lengthening of the route, road clothing

Engineering calculation and estimation of the stress-strain state of the bearing elements of the superstructure is carried out. The analysis and collection of information on traffic in 2019. The history of the loading bridge real load on the basis of mathematical model (presented in the form of a geometric progression) – showing an annual increase of intensity of traffic on bridge construction. The total fatigue damage of the bearing elements of the superstructure according to the Palmgren - miner hypothesis and the period of exhaustion of the operational resource of the bridge structure are determined.

Keywords: load capacity, loading, history of loading, residual resource, the miner's summation of fatigue durability

The results of experimental studies on the formation of cracks in reinforced concrete racks of two slenderness λh = 10 and 20, tested at three eccentricities of load application e0 = 0; 2.0cm (0.16h) and 4.0cm (0.32h). On the basis of the experimental data and the results of calculations on the formation of cracks, it was found that the values ​​of the theoretical moments of cracking of the experimental compressed elements differ significantly from the experimental ones. An analysis was made of the influence of the eccentricity of the load application and the flexibility of the samples on the convergence of the theoretical and experimental moments of cracking in the samples, and the possible reasons for the change in the bearing capacity of the samples were also considered.

Keywords: concrete, reinforced concrete, compressed elements, flexibility, eccentricity, crack, crack resistance

The methodology of numerical experiment of laying with closed method by methods of horizontal-directional drilling, brown-screw drilling, forcing, microtonneling has been developed. Some features of the construction of cases for penetration by collectors under existing highways, including general information about the used materials of the cases, are given. A selection of controlled factors and experiment planning, system stability check, results reliability analysis was performed.

Keywords: collector, numerical experiment methodology, microtonneling, horizontal directional drilling, brown-screw drilling, puncture, forcing, motorway, case, reinforced concrete, metal pipes

This article discusses the theoretical order and practical solution of the problem of calculating the transverse vibrations of a thermosetting polymer self-supporting shell pipe " Furanflex».Сalculation scheme with a finite number of degrees of freedom.The pipe is evenly fixed in height.The procedure for creating a universal calculation algorithm for determining the natural frequencies of pipe vibrations is considered in detail.When creating an algorithm and calculating natural frequencies, determining coefficients, plotting plots, the Mathcad software package is used.When creating an algorithm and calculating natural frequencies, determining coefficients, plotting plots, the Mathcad software package is used. The article may be of interest to design engineers, specialists in calculating the dynamics and strength of structures and specialists of heat-generating companies and thermal power plants, teachers and students of universities in the construction industry.

Keywords: eigenvalues, polymer tube "furanflex", eigenvalues of the matrix

Proper cost estimation, monitoring and control is vital to the success of construction projects. BIM projects allow you to facilitate, visualize, and demonstrate work results. In the estimate documentation, BIM technologies also allow you to improve the process of working on a project. The article discusses the advantages of using BIM - programs for making estimates on the example of Avtodesk Revit and 5D estimates, indicates the main stages of work in these programs. Fewer errors and less lead time are key factors for integrating these technologies into construction pricing.

Keywords: BIM, estimate, 5D смета, construction, design, pricing

The purpose of our work was to search for possible options for the secondary use of destroyed brick buildings and structures. We conducted tests to verify the strength characteristics of bricks taken from the sites of reconstruction and complete demolition of buildings and structures. In the course of which, conclusions were drawn about the possibilities of further use of brick scrap from different places of demolition of building structures.

Keywords: demolition, scrap, building, structure, brick, recycling, testing, strength, recycling, iron concrete

Arched constructions of the roofs of span-type buildings are very cost-effective in comparison with beam and frame systems. In many cases, the high architectural qualities of arch structures allow one to obtain expressive interiors of large halls. At the same time, the construction of long span buildings is always associated with high risks, high security requirements for such buildings, and, consequently, increased requirements for reliability to load-bearing structures, including possible local destructions. Actual becomes the issue of ensuring the survivability of building structures in general, and the construction of roofs for long span buildings in particular. To analyze the survivability properties of shallow arched coverings, a number of constructive solutions of arched constructions of various types are considered. The work of arch structures of various types with possible local caving of a number of elements is considered. Five design schemes of arched constructions are presented, and work of each of them is considered at exclusion of the most loaded elements. In particular, the work of the arch structure with fan-shaped tie system with a split upper belt is considered. A comparative analysis of the survivability properties of the constructive solutions under consideration is presented.

Keywords: arched covers, arch structure with fan-shaped tie system, survivability, local destruction, constructive solutions, long span roofs, progressive collapse

This article discusses the issue of planning the sequence of construction of buildings in the quarter development. The authors analyzed and classified the factors that can influence the choice of the sequence of construction of objects in complex development. An algorithm for planning the construction sequence is proposed, which the considered factors are included in the model, taking into account the ranking of their significance.

Keywords: stream method, quarter development, line arrangement, quarterly arrangement, sequence of construction, situational factor, unforeseen factor, social factor, production factor

For the statically indeterminate systems under consideration, there is an optimal ratio between the load-bearing capacity of stretched and out-of-center compressed elements, in which the required reliability will be provided at the lowest value of the mathematical expectation of an external destructive load. It should also be noted that for statically indeterminate systems, the beginning of rebar fluidity is not a sign of destruction, but only indicates the beginning of an intensive redistribution of forces in it. Therefore, the values of C, do not refer to the beginning of the rebar flow, but to the complete exhaustion of the load-bearing capacity. The reliability of statically undetectable systems, including prestressed trusses, is always higher, all other things being equal, than that of statically definable systems.

Keywords: reinforced concrete, reinforced concrete structures, statically indeterminate systems, reliability

The paper studies the applicability ofthe coercive force (Нс) as a parameter for measuringthe wall thickness ofpipelines,vessels,andother metallic structuresthroughnonmagnetic insulationduring material degradation undercorrosion conditions. A procedure is developedfor remote inspectionof metallic structures atsites of maximum corrosion rateby the coercimetricmethod,withoutbreaking the insulationandstopping the operation ofthe object being tested.The effects of metal thickness, the size ofthe poles of the magnetizer, andthe thickness of non-ferromagneticinsulationon the absoluteand relativevalues of the coercive force are comparatively analyzed. The application of theproposed relative value methodis shown to be able to decrease significantlythe effectof steel composition and structureonthe metal thickness dependence of Нс. The results of measuring the coercive force of differently thick 09G2S steel specimens through non magnetic insulation are presented, as well as the behavior of the relative values of the coercive forceas dependent onmetal and insulation thickness.Foridentical metal thicknesses, the absolute values of the coercive force of different steels may differby a factor of 10 ormore, whereasthe difference in the relative values of Нс with equally decreasing metal thickness does not exceed 15%. The developedtechnique isinsensitivetothe misalignment of the outer and innermetal surfaces,and itenablesthe thickness oflow-alloysteels like 09G2Sto be measured witha relative error of 10%.

Keywords: metallic structure, diagnostics, degradation, corrosion, coercive force, thickness measurement, nonmagnetic insulation

On the basis of experimental data, it was found that when calculating flexible reinforced concrete racks reinforced with composite materials in the transverse direction, the strength of the elements is underestimated by the norms. The influence of the composite reinforcement is not taken into account when calculating the stiffness D, the conditional critical force Ncrc and the slenderness coefficient η. Experimental data from the experiments carried out showed that the deflections of the reinforced struts were less than similar, not reinforced specimens, therefore, the influence takes place. Based on the analysis of the results of experiments, in the methodology of norms when calculating D, proposals were made that take into account the step of the transverse amplification at different eccentricities of the load application.

Keywords: Determination of the conditional critical force of flexible strengthened concrete struts reinforced with composite materials

The article discusses the issues of increasing the efficiency and reliability of the water supply system on the example of gravity water treatment plants. In this study, some of the measures for the reconstruction of structures on the daily regulation pools and introduced new technologies for water purification are considered. The use of a new technology has been studied, which involves the use of local coagulants in the form of aluminum sulfate together with a high-molecular synthetic anionic flocculant of the «POLY SEPAR AN 34 TW» type and clarification of water in sedimentation tanks equipped with horizontal thin-layer modules. As a result of the study, it was identified that the use of anionic flocculant of the «POLY SEPAR AN 34 TW» type, which has a flocculating and disinfecting ability in water treatment processes, is highly effective. Moreover, the use of a flocculant of the «Poly Separ» type for surface water purification at a dose of 0.5 - 1.0 mg/l, along with a decrease in turbidity and color, it ensures the removal of such impurities as iron, heavy metals, a decrease in the total microbial number from 10000 - 1000000 to 100 cells/ml at the filtration stage, since «Poly Separ» has a prolonged bactericidal effect.

Keywords: water supply, pool, regulation, technology, coagulant, aluminum sulfate, anion, flocculant, disinfection, turbidity, color, clarification, kinetics of the process

A method for determining the optimal value of the heat transfer resistance of a three-layer exterior wall of a country cottage building is presented. As an optimization criterion, the specific consumption of thermal energy for the weekly cycle of operation of the building is selected. As a result of the study of the function describing the total specific energy consumption for heat loss compensation and heating of 1 m2 of the outer wall, an analytical expression was obtained to determine the optimal value of the heat transfer resistance. Based on the obtained solution, the thickness of the monolithic expanded clay concrete used as a structural and thermal insulation material in the outer wall is optimized. An analytical relationship is obtained to evaluate the energy-saving effect due to additional insulation of the outer wall of a country cottage.

Keywords: intermittent heating, heat transfer resistance, enclosing structure, energy consumption, heat protection characteristics

Setting the indirect reinforcement in the form of cross welded mesh is one of the effective ways to increase the strength and deformation characteristics of compressed concrete. When performing engineering calculations of structures with indirect reinforcement, in order to ensure the required reliability, it is necessary to use the design values of the strength of materials. At the same time, initially the calculation formulas were derived and analyzed for the experimental average strength values, which are significantly higher than the design ones. Based on the results of the calculations, it was found that a simple substitution of the calculated strength values in the formulas leads to an overestimation of the strength and ultimate compressibility values of concrete with indirect reinforcement.

Keywords: indirect reinforcement, welded mesh, volumetric stress state, compression diagram

The analysis of the functional purpose of high-rise buildings in Russia and abroad is presented. The dynamics of the growth of construction of ultra-tall buildings for the period 2000-2020 is considered. The trend towards the use of composite materials in the construction of ultra-high buildings is revealed. The dynamics of growth of construction of high-rise buildings in Russia is considered. Revealed changes in the functional purpose of high-rise buildings in Russia on the example of the tallest buildings in the Russian Federation. Changes in the use of construction technologies and materials in the construction of high-rise buildings and their impact on the quality of buildings under construction are presented.

Keywords: high-rise buildings, construction, building materials

" This article deals with the problem of fixing bulk and weak soils, leveling the deformation properties of soils during their water saturation. The technology of injecting the fixing cement-sand solution, closed with a solution of liquid glass, was described on the example of fixing the base under the foundations of a residential building under construction in the floodplain zone of the Taganrog Bay on Kruysa Street.

Keywords: structurally unstable soil, hydrogeological risk, floodplain zone, foundation consolidation, cementation, liquid glass, cement-sand mortar, foundation plate, deformation, ground water

A theoretical study of the influence of geometric tolerances of reinforcement on the correspondence between delivery by weight and total length in meters of wire or rods is presented. The issues of efficiency and strength of bent reinforced concrete elements are considered, taking into account the influence of geometric deviations from the nominal values established by the norms for reinforcement of various classes. The documents of the regulatory framework regulating the design and construction and construction activities in the Russian Federation, as well as the works of domestic and foreign scientists, corresponding to the research in this area, were used. Used research methods such as structural and analytical analysis. The types of supplies of reinforcing steels, regulated by the current legislative framework and widely used in the practice of design and construction, are analyzed. Specific proposals have been developed for determining the need for reinforcement in weight and linear measurements, as well as for calculating the strength of reinforced concrete elements. It was revealed that the normalized deviation of the cross-sectional area significantly affects the length of the bar in unit of weight. Boundary values for the length of the rods have been determined for various diameters and classes of reinforcement.

Keywords: reinforcement, reinforcing bars, diameter, tolerance, reinforced concrete, reinforcement delivery, strength, cross-section, technical and economic indicators