Problem statement. The main purpose of the research is to study changes in the strength of clay soil under conditions of triaxial compression, under block mode cyclic loads. To date, there are no data on the results of studies of changes in the strength of clay soils under cyclic loading for the considered modes. Results. Theoretical studies of the strength of clay soils under conditions of triaxial compression ?1 ? ?2 = ?3 under block mode cyclic loads are carried out. A distinctive feature of the research is that the change in strength is described in terms of the mechanics of the destruction of elastic-plastic bodies and the main criterion is the formation and development of micro- and macro-cracks to the limit values. The regularities of changes in the main strength characteristics of the soil during transitions to blocks with high and low stress levels are established. New data on the regularities of changes in the strength of clay soils under stationary and non-stationary modes of cyclic loading are obtained. Conclusions. The significance of the results obtained for the construction industry lies in the study of changes in the fatigue resistance to destruction of clay soils under three-axis regime block cyclic loading. It is established that the stress-strain state and fatigue strength of soils change depending on the sequence of alternating blocks with different values of the maximum load of the cycle.

Problem statement. In reinforced concrete bent structures with repeated cyclic loads of stationary mode in the concrete of the compressed zone, the modulus of elasticity decreases and inelastic deformations of vibration creep develop. Due to the fact that creep deformations occur in connected conditions, the concrete deformations of the compressed zone are non-stationary even in the stationary mode of external load. Results. Theoretical studies of concrete behavior under stationary and non-stationary modes of repeated cyclic loading are carried out. To assess the change in the endurance limit and elastic modulus of concrete under such deformation modes, studies were conducted using the methods of fracture mechanics of elastic-plastic materials and engineering methods for calculating the endurance, deformations and elastic modulus of concrete for stationary and non-stationary deformation modes were obtained. Based on the conducted research, the equation of changes in the strength, modulus of elasticity and deformations of concrete was developed for practical calculations of reinforced concrete bending elements in stationary and non-stationary modes of repeated cyclic loading. Conclusions. The significance of the results obtained for the construction industry is that the proposed method allows the most accurate assessment of the stress-strain state of concrete in the compressed zone and the processes of concrete change from the point of view of fracture mechanics, which is a significant contribution to the theory of fatigue strength and provides concrete savings of up to 35 % compared to existing methods.

Problem statement. The purpose of the study is to determine the durability of three-layer sandwich panels made of polyurethane foam, depending on the purpose, condition, and areas of operation. Results. The main results of the research consist in the analysis of normative prerequisites for the issue of prediction of the durability of enclosing structures; the selection of performance indicators, depending on the purpose of construction; the development of the finite-elementary model of roof sandwich panels to investigate the nature of the influence of the shear modulus and elastic modulus on the performance characteristics; the establishment of dependence of durability of roofing from the parameters of the sandwich panel; determining the durability of sandwich panels for walling, depending on the condition of operation. Conclusions. The significance of the results obtained for the construction industry consists of improving methods for predicting the durability of enclosing structures, which allow determining the service life of building materials and products.

Problem statement. The work aimed to study a method for increasing the strength of fine-grained (sandy) concrete with the combined use of active pozzolanic fillers of natural and technogenic origin in its composition. Results. The results of the combined effect of fly ash and metakaolin on the technological and physical-mechanical parameters of fine-grained (sandy) cement concrete (cone spread, air content and density of the concrete mixture, bending and compressive strength) are presented. By the method of mathematical planning of the experiment, regression equations for the mobility and strength of concrete are derived, and the contribution of each filler to the kinetics of its hardening is estimated. The reliability of the results of the work is justified by calculating the confidence interval and homogeneity of variances using Cochrans criteria, as well as checking the model for adequacy taking into account the Fisher coefficients. Conclusions. The significance of positive results for construction lies in the possibility of using active fillers of both technogenic and natural origin. It is shown that metakaolin makes the greatest contribution to the kinetics of hardening at an early age (up to 7 days), and fly ash at the later hardening periods (28 days). Thanks to their combined use, it is possible to obtain high-strength fine-grained concrete with a compressive strength of over 100 MPa.

Problem statement. Expansion joints are an important element of the bridge construction. One of the most reliable expansion joints is a joint with a rubber compensator. The quality of its installation depends on road safety and the durability of its work and other bridge constructions. The purpose of this work is the improvement of the quality control system for expansion joints with rubber compensators during the repair of bridge constructions. Results. In the first stage of the research an analysis and classification type of expansion joints of bridge constructions was accomplished. In the second stage, a visual inspection of the technical condition of the expansion joints of bridge constructions in Kazan was carried out, their main defects and damages were systematized. In the third stage, the requirements for quality control of the device of deformation joints with a rubber compensator was systematized. Conclusions. The significance of the obtained results for the construction industry consists in clarifying the quality control system for the device of expansion joints with a rubber compensator during the repair of bridge constructions. The main types and classifications of expansion joints have been studied, their main defects and causes of occurrence have been analyzed. The technology is presented and the system of quality control of technological processes of the device of single-profile expansion joints with rubber compensators during the repair of bridge constructions is proposed.

Problem statement. The aim of the work is the optimal picking of construction machines that perform different technological operations for a given process in conditions of complete certainty. Results. In the course of numerical analysis of the optimal picking of construction vehicles, the unit costs of the works are determined. The calculation is based on the dynamic programming method and the optimality principle created by R.E. Bellman. The optimization task is simplified by a local search for the optimal solution, that is, the entire system is divided into parts and for each part a minimum cost value is searched. The calculation algorithm is developed in the computer-aided design system MathCAD. The program allows us to change the source data to calculate any set of machines, according to the selected optimization criterion. Conclusions. The significance of the obtained results lies in the fact that with the optimal picking of construction vehicles, the costs of work are minimized. Due to the calculation using the program, the time for selecting the optimal complex of machines is reduced, the rate of automation of design is increased.

Problem statement. The aim of the work is to numerically simulate the processes of hydrodynamics and heat transfer in conical coil heat exchangers of the «pipe-in-pipe» type with a heat-exchange element in the form of a smooth pipe, to assess the energy efficiency of such devices. Results. The main results of the study are that in the course of the work, the authors developed a model and an algorithm for calculating tapered coil heat exchangers of the «pipe in pipe» type, implemented in the Ansys program, and determined the thermo- hydrodynamic indicators of the coil devices. Conclusions. The significance of the results obtained for the construction industry lies in the possibility of using modern, more efficient and compact heat exchange equipment for the technological needs and justifying this choice. Therefore, with equal initial data, conical heat exchangers are more efficient in comparison with cylindrical ones with a heat exchange element in the form of a smooth tube, since they have a smaller heat exchange surface to achieve the required thermo- hydrodynamic parameters.

Problem statement. The purpose of the study is to analyze the existing situation of the green structure of the city of Mendeleevsk, to identify prospects for the development of urban green areas. Results. A comprehensive analysis of the territory was carried out, including a literary, historical-chronological and architectural-urban planning analysis of the city territory, a field survey. The article analyzes the main urban green areas and formulates recommendations for their development. Conclusions. The significance of the results obtained for urban planning and architectural planning practice is the possibility of forming a new image of the city using public spaces landscaping. A comprehensive analysis of the city’s green structure and recommendations can be useful for further development of the Mendeleevsk master plan.

Problem statement. The purpose of the study – definition, identification and preservation of the historical and cultural identity of the industrial city to urban reconstruction urban, and architectural spatial environment of 70-80ies of XX century the large industrial cities on the example of the Mesopotamian city of Naberezhnye Chelny by highlighting the positive qualities of architecture and urban planning principles, typical for this period, and their conservation and use in new construction. Results. The main results of the research are to form the methodology for preserving and adequate development of the historical and cultural identity of large industrial cities on the example of the city of Naberezhnye Chelny. Conclusions. The significance of the results obtained for modern architectural and urban planning industries is to allow using the developed methodology in real practice of urban development of existing urban systems in the industrial period.

Problem statement. The purpose of the study is to identify the features of the formation of public centers in the structure of administrative districts of Kazan, to determine their specifics, taking into account the existing spatial structure and the needs of the population. Results. The main results of the research are to identify the features of placement, formation and typology of public centers in the structure of administrative districts of Kazan; principles of their placement and formation, development of a model of functional planning organization of public centers of administrative districts of Kazan. Conclusions. The significance of the results obtained for architecture and urban planning is that the identified features and typology of urban public centers in the structure of administrative districts of Kazan allow us to understand changes in the planning structure of the city, identify trends in the transformation of the urban framework and determine the features and directions of reconstruction of fragments of urban territories.

Problem statement. The architectural and planning organization of cooking studios in the early 21st century is becoming an actual form of public space. The purpose of the study is to identify the design basis of a recommendation character for the architectural and spatial organization of a cooking studio. Results. The main results of the research are to determine the development trends of cooking studios in 2000-2018, identify spatial zoning techniques, and form ways to organize multifunctional cooking space. It is shown that in the culinary sphere there are spaces with a different set of functions: educational, professional, and entertainment. These are cooking studios that host corporate events, team building events, and celebrations for young and middle-aged people. To date, there are four establishments with an entertainment function in Kazan. With a training function in the field of cooking in Kazan, there are fourteen spaces. Unlike Kazan, Moscow has space where the capitals chefs can engage in creative activities and culinary experiments, or where chefs can conduct events to improve their professional skills. In Europe, cooking studios are initially focused on changing and transforming the space. This allows them to retain the customer market, unlike Russian cooking studios, each of which was designed with a specific use case in mind. The need to organize a multifunctional space with a combination of functions is the main method of the architectural and spatial organization of any Studio, including cooking. Conclusions. The significance of the results obtained for architecture and design is that based on the identified techniques, it is possible to form and adjust the design basis for the organization of cooking studios in particular and studios in General. The basis of an architectural and planning organization is a multifunctional space that can be transformed for training, professional, and entertainment functions.

Problem statement. The aim of the work is to analyze the influence of translucent fences on the creation of a light environment in the prayer hall and interior spaces, with the traditional three-dimensional solution of stone mosques in Kazan of the late XVIII-early XX centuries. Results. Based on the study of stone mosques in Kazan of the specified period, it was revealed that the main factor was the creation of a complete architectural image of the mosque, in accordance with the time style and the solution of the internal light environment, due to windows and stained glass windows that were scaled using architectural elements and decor, for a holistic perception of the object. Conclusions. The significance of the results obtained for architecture is to present recommendations for their organic use in the restoration and design of modern mosques based on the identified techniques and methods of work studied at architectural heritage sites.