Introduction. In recent years, the use of composite materials for improving the operational properties of the building constructions within the restoration process is gradually replacing the methods, developed for this purpose in the middle of the XXth century and implying the use of reinforced concrete and metal. However, the regulatory framework stipulating the process of strengthening the loadbearing structures of buildings and structures was developed based on the insufficient amount of experimental data. Due to this fact, the large number of structures, exceeding the normative limits, cannot be strengthened with the composite materials, or such strengthening incurs significant economic costs. Thus, nowadays, the experimental studies on strengthening the reinforced concrete structures with composite materials are considered to be forward-looking and relevant. The aim of this study is to analyse the results of a number of experiments conducted to investigate the use and efficiency of composite materials in construction.  

Materials and Methods. To determine the level of stress in composite carbon materials of the external reinforcement of the eccentrically compressed reinforced concrete poles, the tests were carried out with four specimens. All specimens were strengthened using different reinforcement schemes. The strain gauges with 2 cm active measuring grid length were installed in the zones of the most evident work of the composite materials to measure the changes of relative deformation at each load level during testing of the specimens. From 10 to 16 strain gauges were installed at each structure, depending on the importance of the zones for determining the deformations.

Results. The work presents the results of the study on determining the efficiency of composite longitudinal and transverse reinforcement for increasing the rigidity and strength of flexible eccentrically compressed reinforced concrete poles. The experimental data on the composite materials’ strength, deflections and relative deformations, obtained during testing of four reinforced concrete poles, is presented. The efficiency of composite reinforcement at ultimate strength and ultimate deflections is assessed. The relative deformations in composite materials are determined and the inclusion of the reinforcement system in the work of the strengthened reinforced concrete specimens is assessed.

Discussion and Conclusion. Based on the obtained results, the analysis of the composite reinforcement efficiency has been carried out, and proposals have been developed on designing the reinforcement systems of the flexible eccentrically compressed reinforced concrete poles working with the large eccentricities of the load application. 

Introduction. The modern methods of analysis and conducting the numerical experiments referring to calculation and design of constructions are mostly aimed at a deeper study of parameter changes of different structures exposed to the influence of the certain loads. Due to the course of time and upon obtaining and analysing the new results of the numerical studies, there arises the need to revise and update the normative documents developed in the past in the frame of studying the certain modes of structures’ operation. Bearing in mind the above-mentioned objective, the numerical study presented in this article has been carried out.

Materials and Methods. It should be mentioned, that most of the previously conducted research was based on the results of the short-term exposure of the structures to the loads, but not enough attention was paid to the study of the influence of the long-term loading on the structures' operation. This paper presents the results of the numerical experiments investigating the load-bearing capacity, flexural rigidity and maximum force of the power transmission line poles exposed to the short-term and long-term loads. The specimen under study is the cylindrical power transmission line pole complying with the GOST 22687.2 “Centrifugal cylinder reinforced concrete posts for high-voltage transmission lines”.

Results. The paper presents the results of studying the behaviour of the cylindrical reinforced concrete poles, serving as the supports for the electrical power transmission lines, under the short-term and long-term loading. The work provides the results of numerical experiments investigating the strength and rigidity parameters of the above-mentioned structures under different types of loading, as well as upon changing the eccentricities of the application of these loads. The assessment of the rigidity parameters change under the long-term exposure of the poles to the loads is carried out.

Discussion and Conclusion. Based on the results, obtained during the numerical experiments, the strength and rigidity parameters of the annular section power transmission line poles were analysed, and proposals for improving the design codes were made that could become a basis for the further research on this issue.

Introduction. A three-layer structure, though having a small weight, possesses enough rigidity and strength to withstand various force and physical impacts of both static and dynamic nature. By altering the combination of materials and thicknesses of the loadbearing layers and the core, it is possible to achieve the desired physical and mechanical properties of a three-layer structure. In this regard, this paper investigates the stress-strain state of a three-layer beam of different thickness of loadbearing layers and height of the core.

Materials and Methods. The three-layer beam design based on the well-known calculation methodology is presented. A three-layer 70 cm long beam was examined as an example, its width was altered depending on the face size of the hexagonal cell of the core. The thickness of loadbearing layers was altered from 1 to 1.5 mm and the thickness of the core from 0.12 to 0.30 mm. The loadbearing layers were made of the AMG2-H (АМГ2-Н) aluminium alloy, and the hexagonal honeycomb core – of the D16-AT (Д16-АТ) aluminium alloy.

Results. Based on the obtained data, the graphs of the stresses and strains (deflections) alteration dependence on the distributed load were plotted for each of the tested specimens. The graphical dependences were given for the symmetrical and unsymmetrical three-layer beams.

Discussion and Conclusion. The obtained theoretical data on deformations (deflections) and stresses allowed determining the efficient combination of the loadbearing layers, which would make a three-layer beam efficient. Based on the analysis of this data, the conclusions on enhancing the three-layer beam efficiency were made. 

Introduction. Nowadays, in the frame of development of the new territories, when building the industrial and business facilities, there arises the need to develop the territories having the so-called complicated engineering-geological and mining-geological conditions. Ensuring the normal operation of the buildings and structures built on the territories of the land slide hazard, subsiding soils and on the underworked territories is the problem which is relevant to solve.

Materials and Methods. The parameters of the new geotechnical method of the structure tilts elimination by digging a deep trench along the outer contour of a foundation slab’s part are investigated. The soil massif is modeled by the solid finite elements. Correlations for determining the Poisson coefficients of the soil as a function of its strength properties are proposed. The problem is solved taking into account the building and mounting works sequence. For this purpose, the "Mounting works" module of the "Lira" software has been used.

Results. The implementation of the geotechnical method of eliminating the tilts allows ensuring the overall stability of the soil massifs during the works. It provides the opportunity to hold the maximum pressures acting on the massif fixed within the values slightly differing from the mean pressures of the normal operation of the structure. Moreover, deepening the compensation trench causes practically no changes of the vertical pressures values, which leads to the pressures dis-placements deeper into the soil massif. The possible reasons for the subfoundation extra settlements, in case of implementing this method of tilts elimination, are investigated. It has been found that these processes are related to the lateral pressures reductions in the soil massif due to the subfoundation pliability increase, as well as to the edge pressures rises beneath a foundation slab.

Discussion and Conclusion. The proposed method of tilts elimination (geotechnical method), which includes the design of a compensation trench along the building foundation contour, minimises the impact on the massif’s overall stability and reduces the impact on the nearby buildings and structures during eliminating the tilts of the existing foundations. Practical recommendations for correcting the tilts by the geotechnical method are given. 

Introduction. At present one of the pressing issues of the wall ceramics production is manufacturing the large-sized ceramic stones with compressive strength of 10–15 MPa, thermal conductivity less than 0.12 W/(m ·°C) and market price of 5000–6000 rubbles per 1 m3, which would be able to compete with the foam concrete blocks. This task can be solved by developing a modern energy-efficient technology of production and using the opoka rocks as the main raw material and the by-products of coal benefication as the fuel-burning additive.

Materials and Methods. The opoka rocks of the southern Russia deposits Nagolnovskoye, Bakanskoye, Shakhtinskoye, Avilo-Fyodorovskoye and the coal slurry produced at the Pyramida LLC were used for the research. The study of the chemical and mineral composition was carried out on the prepared specimens using the standard methods. The study of the ceramic and technological properties of raw material (plasticity, molding water content, degree of fineness, air and firing shrinkage, compressive strength, water absorption) was carried out according to the common methodology, using the test specimens preground to a certain grain-size composition. This was required because, depending on the opoka type, it might not swell or swell slowly on wetting.

Results. Pre-firing technological properties of the opoka rocks and their differences from the traditional, swelling on wetting, clay raw materials were confirmed: increased molding water content, small air shrinkage, low sensitivity to drying. The dependence of the specimens’ density and strength on opoka degree of fineness, firing temperature and the amount of coal slurry in the raw-material mixture has been established. The optimal amount and influence of the coal benefication by-products on the physical and mechanical properties of the firing specimens have been determined. Adding the coal slurry has made it possible to exclude or minimize the use of gas for firing. On the basis of the obtained results a simplified process flow chart for the minimal prime cost manufacture of the large-sized stones has been developed.

Discussion and Conclusion. The proposed process flow chart comprises two basic units of mixture preparing equipment, the molding of products is carried out by semi-solid extrusion, the drying of products is carried out directly in kiln cars, whereas the coal slurry added into the raw mixture is used for firing. These factors and technological methods allow getting the products with the low thermal conductivity, but with the strength 3–5 times higher than that of the similar density foam concrete blocks. The ceramic stones prime cost will amount to 3000–3500 rubbles per 1 m3 of products. The deposits of the opoka rocks and stock of the unused technogenic coal raw material available in Rostov region can make it a centre of the low cost large-sized ceramic stones manufacture and ensure supply of the high-quality wall materials to the southern and central parts of the country.

Introduction. During construction of the massive monolithic reinforced concrete structures, concrete hardening takes place in the unsteady abnormal temperature conditions, which, along with the massiveness of the structure and concrete recipe features, influence significantly on the concrete strength gaining kinetics. The non-homogeneity of the temperature field leads to the difference of the hardening concrete strength and deformation indicators in the different points of a structure at one and the same time, eventually resulting in formation of the non-homogeneous stress field. Due to the insufficient number of publications dedicated to the topic of forecasting the dependence of the strength of concrete on the time and temperature conditions of its hardening and recipe features, the research in this field becomes a relevant objective. Thus, the aim of the work is to determine a mathematical dependence of the strength gaining kinetics of different concretes on the reduced time of hardening parameter, the dependence which is necessary for calculating the thermal stress of the massive reinforced concrete structures at early-age hardening in the unsteady temperature conditions.

Materials and Methods. The data received during the authors’ experiments and calculations, as well as the data available in the existing publications and regulatory documents was used. Theoretical assessment of the concrete strength gaining kinetics, depending on the cement type hardening kinetics, was done. The assessment took into account the actual heat of hydration of the hardening concrete and its temperature, including the unsteady one, and was based on the following provisions: the kinetics of cement heat of hydration can be considered as the cement hydration degree and strength gaining indicator; the cement hydration degree in a given moment of time determines the porosity of a cement brick, and the strength of a cement brick and concrete is determined by the porosity thereof.

Results. The dependence of the relative strength of concrete on the reduced time of hardening parameter in the unsteady temperature conditions is determined for the concretes having different kinetics of hardening in the normal conditions. The good convergence of the proposed dependence with the results of experimental studies and some normative documents is shown.

Discussion and Conclusion. The scientific concepts on the relative strength assessment of the concrete, hardening in the abnormal temperature conditions, have been further developed based on the hypothesis of the concrete hardening kinetics dependence on the kinetics of cement heat of hydration, taking into account the degree of concrete aging per "reduced time of hardening". It’s worth to use this dependence for calculating the thermal stress of the massive reinforced concrete structures at early-age hardening. The efficiency of assessing the strength gaining kinetics of the various concretes, hard-ening in the unsteady temperature conditions, by using the "reduced time" parameter, has been shown and substantiated. The heat of hydration kinetics and the total porosity magnitude, determined by the hydration degree indicator, have been taken into account. The application of the "reduced time of hardening", depending on the concrete aging degree to assess the relative strength of concrete, with regard to its recipe features, has been substantiated.

Introduction. The efficiency of the foam concrete products manufacture and application in construction is briefly overviewed. The reasons constraining the nomenclature of the manufactured products are listed. The information about evolvement of the foam concrete disperse fiber-reinforcement technology is provided. The need for scientific research aimed at studying the dynamics of the foam concrete technological and operational properties upon disperse reinforcement with polypropylene fibers is formulated.

Materials and Methods. The composition and properties of the materials used for manufacturing the foam concrete mixtures are listed. The methods used for assessing the technological and mechanical properties of the materials under study are indicated.

Results. The results of the experimental assessment of the polypropylene fiber length and amount influence on the dynamics of the plastic strengthening growth of the equally dense foam and fiber-reinforced concrete mixtures are presented. The scope of the polypropylene fiber influence on the dynamics of the studied mixtures plastic strengthening is analysed. The scientific substantiation of the reasons accelerating the mass transfer processes during the disperse reinforcement of mixtures with fibers is given. The results of the bending tensile strength tests of the large-size D600 concrete specimens are presented.

Discussion and Conclusion. The efficient positive influence of the polypropylene fiber, in correlation with its length, on the following foam concrete properties has been distinguished:

• speed of phase transfer;
• ultimate extensibility;
• elasticity and strength modulus of D600 concrete.

Introduction. Numerous works devoted to studying the physical and mechanical properties of bamboo and the methods of bamboo rods’ node connections are identified. The main "bamboo" countries, where bamboo is becoming popular as a structural material in the modern construction industry, are listed. Due to development of the modern processing technologies, bamboo is widely used in the construction industry, including the slab and board manufacture, as well as the decoration and indoor finishing in the oriental style. The results of studying the physical and mechanical properties of various types of bamboo conducted by the scientists from different countries are currently integrated into three ISO standards regulating the rules of bamboo application in construction.

Materials and Methods. Studying the bamboo macrostructure makes it possible to specify the superior mechanical properties attributed to natural and artificial polymers. Such an approach to studying bamboo and wood as natural polymers makes it possible to apply the methods used in testing the wood and engineering plastics to determining the mechanical properties of bamboo. Two sets of specimens each consisting of five items have been produced. The geometric specification tables of the specimens’ cross-sections have been drawn up. A design solution has been proposed to strengthen the head of a specimen with the epoxide compound aiming to improve reliability of fixing a specimen in the test unit grippers.

Results. To determine the bamboo tensile elastic modulus, a test unit consisting of two grippers, into which a test specimen is placed, has been developed and manufactured. Through the lower gripper, the test load has been applied by means of a steel pull rod with a loading platform, on which the calibrated single-piece loads have been put. To determine the magnitude of the absolute elongation of the specimen base in tension, the contact deflectometers, i.e. the Mitutoyo dial gauges (Japan), have been used.

Discussion and Conclusion. The formula for determining the tensile elastic modulus is given. Finding the arithmetic mean value of the tested specimens’ elasticity modulus and the mean square deviation of the elasticity modulus is considered to be the result of the test. The analysis of the obtained results allows us to conclude that the experimental values of the tensile elastic modulus of Moso bamboo validly coincide with the values known in the technical publications. 

Introduction. Implementation of the innovative technologies and materials into construction industry is constrained due to a number of reasons related to the insufficiently well studied production processes of the highly efficient innovative materials and their high cost. Therefore, studying the production process of the monolithic concrete structures, which is bearing the features of concreting the structures made of the self-compacting mixes and is targeting the prime cost reduction by using the construction waste, is relevant. The research aims at experimental and statistical modeling the dependence of the rheological properties of the fine-grained self-compacting concrete mixes and physical and mechanical properties of concretes on two recipe factors — consumption of superplastifying additive and grain-size composition of an aggregate containing the construction waste.

Materials and Methods. To prepare the fine-grained self-compacting concrete mixes, the Portland cement CEM 0 52,5N, natural quartz sand, crushed concrete sand mixed of three fractions 0.63–5.0 mm and a chemical additive — an ester-based polycarboxylate superplasticizer Polyplast PK, were used. The technological properties of the fine-grained self-compacting mixes (workability, viscosity, fluidity) were determined using the standard methods. The shear yield stress for the mixes was determined by means of an instrument consisting of a cylinder with a mouth and a glass base with marked circumferences. Modeling the rheological and physical-mechanical properties of the fine-grained self-compacting concretes was carried out based on the two-factor simplex sum mathematical planning visualised in a hexagon figure inscribed in a circle, which is one of the most appropriate methods of solving the technological problems in the construction materials science.

Results. The experimental-statistical models of the rheological properties of the fine-grained self-compacting mixes and strength properties of concrete were obtained, providing the adequate description of the experiment data.

Discussion and Conclusion. The mathematical planning used in the experiment made it possible to comprehensively assess the influence of two most significant recipe factors on the process of concreting the monolithic reinforced concrete structures made of fine-grained self-compacting mixes using the aggregate from the construction waste. It was determined that the optimal content of the crushed concrete grains in natural sand was 30–35 %, and proportion of the superplasticizer Polyplast PK was 1.2–1.25 % to the weight of binder.

Introduction. Within construction operations the problem of making more trustworthy the information included in the certificates of inspection of hidden works is most often solved by means of photofixation thereof. Based on the previous research results, the authors prove that diagnostic informativeness of the photographs can be used not only to confirm the fact of executing the hidden works in the required scope, but also to get additional information about their quality. To be able to retrieve this information efficiently it is necessary to develop the methodology for controlling quality of the hidden construction works by means of the photographs attached to the certificates of inspection, using advanced scientific achievements in the field of photogrammetry and colour texture analysis of photographic images.

Materials and Methods. The developed quality control methodology of the hidden construction works is based on the use of contour, pixel, macro- and micro-texture analysis of the photographic images. When developing the present methodology, the results of numerous visual examinations of the building structures (including their internal elements’ uncovering) have been used and compared against the information in the certificates of inspection of hidden works.

Results. The article presents the results of the study conducted at Don State Technical University on development of the quality control methodology of the hidden construction works by means of the photographs attached to the certificates of inspection. The algorithms developed by the authors for analysing the photographs of the building structures to control their quality have been presented. The proposals on systematisation and storage of the typical textures of the building structure surfaces have been provided.

Discussion and Conclusion. The foremost condition for successful implementation of the new methodology of the hidden construction works quality control is its methodological support, which determines the unified procedure for photofixation, additional requirements to the combination and parameters of photographs, rules of their registration, storage and use as annexes to the certificates of inspection of hidden works, as well as provides the guidelines for the comprehensive analysis of photographs using the appropriate software.

Introduction. The main way to assess the load-bearing capacity of the road structures (which represent the layered mediums consisting of the materials of different rigidity) is by testing them with the impact loading test facilities. The analysis of the results of such tests reveals that they focus only on studying the peak values of vertical movements without taking into account changes of these parameters in frequency or time. However, it is the study of amplitude-frequency specifications of movements that can enable solving a number of pressing problems, e.g., related to bringing the actual values of vertical movements to the values of design mode operation of the structure. The aim of the present research is to analyse the dynamic response of the motorway layered mediums (road structures) to the impact load in order to bring the actual parameters of the dynamic response to the design parameters, which comply with the requirements of the national regulatory documents on road design.

Materials and Methods. The modern impact loading test facilities make it possible to simulate the impact pulse duration of 0.03s, while the design values of the elasticity moduli equal to 0.1s. To overcome this discrepancy, the authors have implemented the precise solution of the dynamic Lame equation for a multilayered half-space and have drawn up a number of amplitude-frequency specifications of movements, which have been processed and have become a basis for deriving a simple functional dependency.

Results. The methodology of drawing up the amplitude-frequency specifications of the movements on the road pavement surface, subject to impact action, has been developed and implemented in practice. Based on the precise solution of the dynamic Lame equation, by using the statistical processing, a simple regression dependency for calculating the vertical movements has been determined. An example of the elastic moduli calculation of the road structure layers, taking into account their dependency on the load application time, has been presented.

Discussion and Conclusion. Within the framework of the research, for the first time, a methodology has been developed for bringing the actual values of vertical movements to the values of design mode operation of the road structure based entirely on the computational analysis of its dynamic stress-strain state (SSS), in particular, the amplitude-frequency specification of deformation under the non-stationary impact. The developed approach contributes significantly to increasing the credibility of the motorway condition diagnostics, as well as ensures the integrity of measurements and results obtained during the road design and diagnostics. 

Introduction. Botanical gardens are the special research institutions fostering the conservation and introduction of various plant species. They have gone a long way in their development and play an important role in organisation of people’s recreation within the urban nature-based framework. The research revealed, that in the botanical gardens the research activities are combined with the considerable work on the architectural planning and landscape-spatial arrangement of territories, all contributing to the rational layout and functioning of the botanical gardens. The aim of the present research is to analyse and identify the main principles of forming the territories of botanical gardens in the south of Russia, find out their functional set-up and modern trends of development, which have not been studied before.

Materials and Methods. The comparative analysis of the state of territories of botanical gardens per time and space, the integrated system analysis of the architectural planning and landscape evolution features of the territories of botanical gardens of the south of Russia and the principles of their design from perspective of the landscape architecture, were carried out. When conducting the evaluative research of the territory of the Botanical Garden of the Southern Federal University in Rostov-on-Don, the graph analytics methods were used, as well as the authors’ graphic materials on reconstruction of the SFU Botanical Garden structure.

Results. The main historical stages in the timeline of botanical gardens’ formation in Russia were determined. The evolution of the architectural planning and landscape arrangement of the botanical and dendrological gardens in the southern region of Russia was analysed for the first time. The results of the study allowed making a conclusion about the insufficient consideration of the recreational role of the territories of botanical gardens and principles of their arrangement as the landscape objects during their design and creation. The main principles of forming the territories of botanical gardens in the southern region of Russia were formulated. By the example of the Botanical Garden of the Southern Federal University of Rostov-on-Don, the features of its territory formation, creation of the collection stock, arboretum, etc., were revealed. The disadvantages and advantages of zoning its territory, from perspective of forming it as a landscape object, were determined. Conceptual proposals for the transformation of its territories were given.

Discussion and Conclusion. The authors have systemised the data per historical periods of the botanical gardens’ for-mation and evolution in Russia, which enables considering the revealed features during the reconstruction of such territories. For the first time the specifics of the southern region botanical and dendrological gardens’ formation, as the land-scape objects intended for recreational purposes, have been studied. The formulated principles of functional zoning of the botanical gardens of the south of Russia will enhance their architectural-artistic and landscape image. Based on the materials of this study, the conceptual design solutions for the territory of the Southern Federal University Botanical Garden of Rostov-on-Don have been provided.

Introduction. The scientific problem tackled by the authors is the need to analyse and evaluate the life cycle of the air conditioning systems (ACS) for developing an optimal technology of creating the favourable indoor climate, which enables people’s productive work and rest as well as the normal flow of the technological processes. The study aimed at investigating the life cycle of an ACS as a facility of the comfortable indoor climate provision within the urban mixed-use complexes.

Materials and Methods. The authors' research is based on the methods of mathematical and system analysis used to find out the solution for extending the life cycle of the indoor climate provision facilities.

Results. As a result of the research, the ACS main life cycle stages were distinguished, their relations to the respective operational parameters were determined, the formulas for calculating the criteria and nondimensional indicators of the indoor climate provision system’s operation assessment were proposed.

Discussion and Conclusion. The carried out analysis on distinguishing the life cycle extension capacities allowed us to conclude that the ACS operational stage provides the best opportunities for selecting the optimal layout of the system functional units and the air conditioning technology. The formulas for calculating the criteria and their respective nondimensional indicators enabling the development of the recommendations and ways of extending the ACS life cycle have been determined and described.  

Introduction. In the article a mechanical ventilation system is investigated by the author as a complex technical system, which can be efficiently managed based on its life cycle model. Like any engineering system (or a product, article of manufacture, project), a ventilation system has its own life cycle, consisting of a set of successive stages. Each stage is characterised by the types of work and final results attributed to it, which require managerial decisions. The study aims at developing a life cycle model of a ventilation system.

Materials and Methods. The life cycle analysis method of the complex technical systems, the methods of collecting and processing the statistical data, as well as the system and comparative analysis methods, and the method of synthesis of the scientific and practical results have been used in the research.

Results. Within the research conducted by the author, the "life cycle" approach to management of the ventilation systems had been implemented, and the objective of developing a life cycle model thereof, including all stages of system's evolution, from formation of a concept to disposal, had been achieved. Possible ways of managing the ventilation systems life cycle with respect to the uninterrupted interaction of processes had been defined.

Discussion and Conclusion. The efficient life cycle management of a mechanical ventilation system can be implemented through development of a software product capable of modeling the processes and elements of a system, starting from the very first stages of the life cycle. The software product will be able to eliminate the problem of inconsistencies existing at the different stages of work, will store the information about the object and provide access to it to each participant of the process. Solving the software development problem will ensure efficient management of the entire life cycle of a ventilation system, reduce the labour costs, eliminate the inconsistencies and ensure compliance with the modern requirements for the operational reliability and energy efficiency of the vital engineering systems.