Introduction. The Strategy of the Development of the Construction Industry and Housing and Communal services in the Russian Federation provides for the transition to parametric regulation in construction. The article attempts to examine the essence of such a transition in terms of the design of load-bearing reinforced concrete structures from various perspectives. The article discusses the features of such a transition compared to the current principle of regulation, highlights various aspects of such a transition, and examines the possible consequences of their impact on the overall design process. The transition to parametric regulation has both advantages and disadvantages, and therefore the implementation of such regulation in the design practice requires careful and comprehensive assessment, taking into account the existing domestic experience in the design of reinforced concrete

structures.

Aim. To assess the transition to parametric regulation in the design of reinforced concrete structures.

Materials and methods. The assessment was performed based on an analysis of the provisions of the Strategy for the Development of the Construction Industry and Housing and Communal services in the Russian Federation, as well as the provisions of domestic and foreign regulatory and technical documentation.

Results. The general principle of transition to parametric regulation has been analyzed, the positive aspects of such a transition, as well as its disadvantages, have been noted.  Proposals have been formulated to eliminate the disadvantages of transition to parametric regulation in the design of load-bearing reinforced concrete structures.

Conclusions. It is necessary to take into account the development of technologies, calculation methods, approaches to design, the emergence of new materials, and to implement all of this in the practice of designing of concrete and reinforced concrete structures. At the same time, the introduction of such innovations should be based on the fundamental principles of ensuring the reliability and durability of the adopted design solutions. In order to eliminate the shortcomings, the implementation of parametric standardization in the design practice requires careful and comprehensive assessment, taking into account the existing domestic experience in the design of reinforced concrete structures. It seems to be necessary for transition to parametric standardization to prepare a system of voluntary use documents that will allow designers to solve all the problems of building structures designing.

Introduction. Requirements for ensuring operational reliability of structures based on steel fiber concrete served as the basis for conducting a set of numerical and experimental studies aimed at studying its properties and determining the reliability factors for the composite material – steel fiber concrete. The reliability factors recommended by the standards for steel fiber concrete SP 52-104-2006* are assigned separately for the concrete matrix and separately for the fiber reinforcement, and according to SP 360.1325800.2017, “the standard and calculated values of resistance of steel fiber concrete to axial compression are taken equal to their values established in SP 63.13330 for a similar class of ordinary concrete.”

Aim. Based on the principles of formation of properties of classical composite materials and systematization of data on ensuring the properties of steel fiber concrete, conduct comprehensive studies and, based on their results, determine the reliability factors for the steel fiber concrete composite in accordance with the choice of the fiber type and characteristics of the concrete matrix of the designed structure.

Materials and methods. The studies were carried out using numerical and experimental methods. For the preparation of steel fiber concrete, the types of fiber offered by domestic manufacturers and most often mentioned in the studies of Russian scientists were used, fine-grained concrete was adopted as a matrix. Laboratory samples were manufactured according to State Standard 10180-90 and State Standard 310.4-81. Samples of steel fiber concrete were tested for strength and deformability. The test results were statistically processed.

Results. As a result of the conducted research, reliability factors for steel fiber concrete were obtained depending on the type of fibers and the stress-strain state of the sample.

Conclusions. To ensure the operational reliability of structures for various purposes using steel fiber concrete, it is necessary to have reliability factors for the material – steel fiber concrete, the structure and properties of which are formed during the interaction of steel fiber and concrete matrix, in accordance with the dimensions of the section of the designed element. There is an obvious need to introduce unambiguity in the definition of reliability factors for the steel fiber concrete composite into regulatory documents for the design of structures based on steel fiber concrete.

Introduction. In the modern world, where the main emphasis in construction is placed on the safety of human life, in our country we still produce and use steel reinforcing bars that are capable of brittle fracture under negative circumstances due to their high carbon content. In European countries the carbon content is limited to 0.22 % in all non-tensioned rebar at the end of the last century, in our country carbon content up to 0.29 % is allowed. Today’s building regulations allow the use of such high-carbon reinforcing bars even in structures that may be subject to special adverse environmental influences.

Aim. To highlight the problem of the potential brittle fracture of steel reinforcement produced in accordance with existing standards, with the possibility of its use in the construction industry in accordance with Russian codes of practice, including in special operating conditions and in responsible buildings and structures.

Materials and methods. For the experiment, A500C and A400 classes reinforcing bars made of 3Gsp and 25G2S grades steel respectively were used. The properties of the reinforcement and its welded joints were studied using standardised and specialized methods, including tensile, bending and impact tests at temperatures ranging from +20 to -60 °С.

Results. Experimental data characterizing the performance properties of rolled reinforcement bars of different classes were obtained, confirming the possibility of brittle failure of working reinforcement bars manufactured in the Russian Federation and used in accordance with requirements of codes of practice.

Conclusions. The conducted research allows us to see how a reinforcement bars that at first glance are good in terms of plastic properties, can radically change the perception of the quality and safety of its use when evaluating its operational properties.

Introduction. This article analyzes the requirements of current regulatory and technical documents for the protection of buildings and structures from progressive collapse, as well as individual protection methods. The feasibility of improving the load-bearing reinforced concrete elements calculation theory, not only during the element’s service life up to the first special limit state, but also during the special limit state is discussed. Reserves for the strength and deformability of flexural elements are presented.

Aim. To experimentally verify the hypothesis of the neutral axis of a flexural element displacement during loading and to refine its magnitude, including during the special limit state.

Materials and methods. The experimental study was conducted by testing prototypes of flexural elements. A single-span, simply supported reinforced concrete beam was loaded with two concentrated loads through a distribution crossbeam at one thirds of the span. This article describes the experimental setup, characteristics, and prototypes, as well as the measuring instruments used to obtain experimental data on changes in the stress-strain state of a flexural element at all stages of its operation, including the stage of reduced bearing capacity (softening).

Results. This article presents the first part of the results of an analysis of experimental studies (loading stage from 0,8 M_ult to M_ult), aimed, among other things, at determining the criteria for the special limit state of flexural reinforced concrete elements. An analysis of the calculated and experimental values of the relative deformations of concrete and reinforcement, as well as the bending moments determined at the deformation stages, is presented. A methodology for determining the stress-strain state of a structure at various loading stages has been developed and presented for discussion. This methodology is based on the equilibrium equation for external and internal forces acting in the cross-section of a reinforced concrete element, taking into account changes in the position of the neutral axis.

Conclusions. The error in the theoretical results obtained using the authors’ methodology for determining the stress-strain state of a structure, compared to experimental data obtained at the loading stage from 0,8 M_ult to M_ult, was up to 3–5 %, depending on the deformation stage. The hypothesis for changes in the neutral axis position, outlined in the developed methodology and confirmed by experimental research, will be published in the authors’ subsequent papers.

Introduction. The development of large cities in the Republic of Kazakhstan is accompanied by the construction of multi-storey buildings from bulk blocks, in which the main construction processes are carried out in factory conditions, which ensures automation of production, improves its quality, reduces the timing and seasonality of work, provides the possibility of using effective building materials, reduces the cost of construction. A volumetric block housing construction plant has been built in Astana, producing volumetric blocks of the “recumbent glass” type, that checks the main types of volumetric blocks for various structural solutions of buildings.

Aim. Checking the main types of volumetric blocks for vertical and horizontal loads.

Materials and methods. The volumetric blocks were tested on a test bench, which is a rigid rod system of adjustable vertical and horizontal frames. The volumetric blocks were loaded using hydraulic jacks with a capacity of 200 tons each through a reinforced concrete distribution plate. During the tests, compressive deformations of concrete were measured using vertical strain gauges with a base of 50 mm, horizontal and vertical movements of walls and floors using digital deflection meters PA0–6, as well as crack opening width using an MPB-3 microscope.

Results. The article presents the results of experimental studies of the stress-strain state of full-scale volumetric blocks of the “recumbent glass” type under the combined action of vertical and horizontal loads, describes the sequence of formation and opening of cracks, the distribution of longitudinal deformations and stresses of concrete along the perimeter of walls, diagrams of horizontal movements of walls from the plane, the nature of destruction, and recommendations for limiting the number of buildings floors.

Introduction. This study is based on the property of physically dense matter to absorb and reflect light radiation. White-colored materials have a high reflective ability, while black-colored materials completely absorb the waves of the light spectrum of the Sun’s radiation. Since the white color reflects most of the waves of the light spectrum, increasing the whiteness of the “SPADAR SK-450” plaster coating should provide more effective protection of the plastered surface from heat associated with the absorption of photons of light. In this paper, a comparative study of the temperature and heating time of the surface of aerated concrete and “SPADAR” plaster when exposed to direct sunlight is carried out.

Aim. Comparative studies of the temperature and heating time of the surface of aerated concrete and “SPADAR” base plaster and modified with microcalcite and TiO₂ when exposed to these materials by direct sunlight.

Materials and methods. Samples up to 10 mm thick were used for the study: non-autoclaved aerated concrete, base “SPADAR SK-450” plaster and modified with microcalcite and titanium oxide. In the course of the work, there were determined and compared: whiteness of “SPADAR SK-450” plaster according to RAL, depending on its modification with microcalcite and titanium oxide; changes in the surface temperature of the studied samples over time when exposed to direct sunlight. A digital pyrometer CEM DT-812 with a temperature range from -30 to +500 °C was used to measure the temperature.

Results. It was established: a sample of autoclaved aerated concrete, when exposed to direct sunlight, has a maximum surface heating temperature of +42.1 °C, which is 6 °C higher than the minimum temperature of the heated surface of the “SPADAR SK-450” plaster, modified with microcalcite and titanium dioxide when microcalcite and titanium oxide are combined into the “SPADAR SK-450”; the whiteness of the plaster increases, which reduces the temperature of maximum heating of its surface by 0,5 °C in comparison with the basic composition of the “SPADAR SK-450” plaster.

Conclusions. “SPADAR SK-450” plaster reduces the temperature of maximum heating of the aerated concrete surface by 6 °C due to its white color. Modification of the basic composition of the “SPADAR SK-450” plaster by the combined introduction of microcalcite and titanium dioxide into its composition increases the whiteness of the plaster coating and reduces the temperature of maximum heating of its surface by light radiation, which in turn helps to protect the plastered surface from heating.

Introduction. Modern industry standards are characterized by increasing volume and complexity, which makes their manual analysis time-consuming and error-prone. An urgent task is to develop and implement methods of automated, machine-readable representation of standards for their integration into intelligent decision support systems.

Aim. The research is aimed at analyzing the possibilities of artificial intelligence technologies for automating the processes of interpretation, structuring and analysis of regulatory documents, as well as identifying key challenges and prospects in this area.

Materials and methods. Modern NLP methods were used in the work, including tokenization, lemmatization, keyword extraction, semantic analysis based on transformational architectures and text classification. Data analysis included the conversion of text into structured formats (JSON/XML).

Results. The developed approach has demonstrated high efficiency: the time for analyzing regulatory documents has been reduced, and the accuracy of classifying sections of standards has reached 92 %. Using the example of the ISO 27001 standard, the possibility of automatic extraction of structured requirements was shown. An automated comparison of the versions of the standards (using the example of State Standard R) revealed up to 98 % of the changes.

Conclusions. The practical implementation of artificial intelligence methods has confirmed their high potential for automating the machine understanding of standards. Further development is related to the adaptation of models to highly specialized domains, the development of explicable artificial intelligence and integration with expert systems for validation of results, which will contribute to the creation of full-fledged intelligent systems for working with regulatory documentation.