Introduction. The aim of the study is to investigate the problem of bending-torsion and flat-form loss of stability of a thin-walled open-section element. A refinement of V.Z. Vlasov’s technical theory for thin-walled rods is presented. The refined differential equations obtained describe the stability conditions of an I-beam with variable wall height. Closed solutions based on refined differential equations are presented using the Bubnov–Galerkin analytical method. The paper provides comparative graphs that allow the differences between analytical solutions and finite element analysis to be assessed.

Materials and methods. The technical theory of V.Z. Vlasov and the Bubnov–Galerkin method were used.

Results. Based on the clarifications made, a closed-form solution was obtained for the problem of elastic buckling of a rod with a linearly varying wall height. An analytical method was proposed for calculating the bending-torsional and flat forms of buckling of a thin-walled open-section element.

Conclusions. The theoretical work presented demonstrates that the solution to the problem of the plane shape and bending-torsional instability of a beam-column with a linearly varying wall height of an open section can be achieved by refining the differential equations and presented in a closed form similar to that for beams-columns of constant section, but with additional corrections in the form of formula coefficients.

Introduction. One of the crucial aspects of solving various mechanical problems using numerical methods is the interpretation of the obtained results for their further use. Modern computational complexes implementing the finite element method have a so-called postprocessor — a module designed to ease visualization and interpretation of the results of performed calculations. However, no matter how advanced the postprocessor built into the CAE programme is, its functionality may be insufficient for solving a particular engineering task. One of the ways to optimize the relevant stages of work is to use third-party software products and develop custom extensions.

Materials and methods. Determination of the required parameters of reinforcement of monolithic reinforced concrete structures of complex geometric shape is performed in the SCAD++ computer complex, but their further processing by built-in tools is challenging. Within the framework of the proposed methodology, interpretation, and analysis of the results of reinforcement of a monolithic reinforced concrete slab with wide beams obtained in SCAD++ were performed using the freeware software product Gmsh and a user script in the Python programming language.

Results. The implementation of the proposed algorithm of data processing obtained from SCAD++ allowed to overcome the limitations of standard means of CAE system in terms of visualization of the results of the performed calculations. As well as to create initial data for their further use in engineering and construction design.

Conclusions. The proposed methodology is convenient for application in engineering practice and provides wide opportunities for effective analysis of the results of calculations performed by the finite element method and their further processing. Its use will increase the efficiency of decisions taken, improve the design process of geometrically complex structures and their elements, as well as optimize the financial costs of software acquisition.

Introduction. Proper use of insolation effects allows to reduce the costs of heating, ventilation and air conditioning, as well as to minimize heat loss through window and facade structures. At the same time, the development of information modelling technologies (BIM) opens up new opportunities for automation of design processes. The purpose of this study is to develop a methodology for automated calculation of natural lighting according to plans of apartment buildings in the information modelling environment.

Materials and methods. The paper presents a methodology for computer modelling of natural lighting in apartment buildings based on building plans using information modelling and visual programming technologies in the Autodesk Revit environment using Dynamo.

Results. The developed script allows for automatic calculation of the duration of insolation taking into account the geometry of the building, the orientation of the facades, the surrounding buildings and astronomical data. The introduction of this tool into design practice facilitates the efficiency of calculations, reduces labour costs, and ensures that design solutions comply with regulatory requirements for the insolation of residential premises. The results of performance testing are presented, as well as examples of visualization of data on natural lighting.

Conclusions. The developed script and plugin demonstrated high accuracy and reliability when tested on various objects, which confirms their practical applicability. The implementation of the plugin in production processes has shown its effectiveness, which indicates the significant potential of this tool for optimizing design solutions and increasing the energy efficiency of buildings.

Introduction. Dismantling of buildings using explosive energy is an urgent problem, as the process is complicated by a large number of different geometric parameters of collapsed structures, which may not fit the existing collapse methodology, thus complicating the process of dismantling the building. An example of such a collapse object is a monolithic reinforced concrete elevator in the city of Yaroslavl. If the building collapses on its base, the elevator, due to the great strength of the building material, will not collapse. For the collapse of the structure in a given direction, it will be necessary to make a cutout with a large value of height and angle, which will be a difficult technical problem. The authors propose a method to reduce the height of the cut and the volume of special blasting operations.

Materials and methods. The calculation took into account the kinetic energy acquired by the building at the time of the explosion, which created additional forces contributing to its collapse. These forces were not taken into account in the calculations according to the existing methodology. According to the results of the calculation, the volume of drilling and blasting operations was reduced by reducing the values of the angle and height of the cut, which amounted to 21.5° and 3.94 m, respectively. These values are 1.6 times less compared to the results obtained using the existing methodology, where the height of the cut was 6.5 m at an angle of 32°.

Results. The calculated blast parameters were applied to the design of blasting operations for the demolition of four silo buildings of a grain elevator in Yaroslavl. All buildings were successfully demolished, which confirmed the effectiveness of the proposed methodology.

Conclusions. The blasting operations demonstrated high efficiency and practical significance of the developed method. The proposed method allows to reduce the size of the cut by 40 % compared to the existing method, which simplifies and speeds up the performance of special blasting operations, reducing the risks to surrounding objects and increasing the safety of workers by reducing the number of explosives.

Introduction. The proposed paper explores the possibility of using cross-oriented layers in glued wooden beams and determining the stress-strain state of such beams. The main advantage of using cross-oriented layers in glued beams is the possibility of using lumber production waste in cross-oriented layers.

Materials and methods. In this study, 3-layer and 5-layer beams glued together from only longitudinal lamellae and beams combined from longitudinal and cross-oriented layers are considered for comparison. The study is divided into two stages: the calculation of the beam structure in the Lira software package and the bending test of specimens. The test specimens were made using two types of glue: Tricol single-component polyurethane glue and glue based on phenol-formaldehyde resins BF-4.

Results. According to the calculation results in the Lira software package, the normal stresses of 3-layer beams with cross-oriented layers increased by 6.5 % compared to beams without them, and for 5-layer beams with cross-oriented layers, the normal stresses increased by 25 % relative to beams with longitudinal layers. The deformability of beams using cross-oriented layers has changed slightly by calculation compared to beams glued only from longitudinal lamellae. According to the test results, the specimens glued using a one-component polyurethane adhesive showed the best results in terms of strength and fracture pattern. These specimens showed the maximum convergence of the destructive load during testing. The average
convergence of the calculated stresses with the stresses obtained from the experimental results was about 90 %.
The average convergence of the strain calculation results and experimental data was 88.8 %.

Conclusions. Thus, when using cross-oriented layers in the construction of glued wooden beams, 3-layer specimens turned out to be the most suitable for limited use in real structures, which showed a decrease in strengthof about 20 %. The use of cross-oriented layers in glued wooden beams will reduce the waste of lumber production with a slight loss of their bearing capacity.

Introduction. The paper presents the possibility of reducing the reinforcement length of flexible drill-injection piles with diameters up to 0.3 m without compromising their material bearing capacity, based on an analysis of bending moment distribution along the pile length. The relevance of the study stems from the need to find technical solutions that simplify and reduce the cost of foundation reinforcement while maintaining reliability and durability. The main objective is to provide a computational justification for the minimum required reinforcement length of drill-injection piles, considering their actual behavior in soil mass.

Materials and methods. To achieve this goal, the distribution of bending moments was analyzed for piles with diameters of 0.2, 0.25, and 0.3 m in two types of soil conditions. The assessment was performed using known analytical solutions and numerical modelling in Midas FEA NX software. The sufficiency of reinforcement was evaluated based on the ratio between actual loads and the ultimate tensile strength of concrete, allowing determination of necessary reinforcement zones along the pile length.

Results. The analysis of bending moment distribution in flexible piles showed that maximum stresses occur only in the upper section (up to 3–4 m depth), with rapid attenuation of bending moments below this level. For silty-clay soils, the sufficient reinforcement depth for flexible piles up to 0.3 m diameter was established as 15–16 pile diameters.

Conclusions. The study demonstrates the fundamental possibility of reducing reinforcement cage length in flexible drill-injection piles (up to 0.3 m diameter) without compromising bearing capacity. Practical recommendations for reinforcement depth depending on pile diameter and soil characteristics were developed. The results facilitate the installation of small-diameter drill-injection piles, particularly in confined working conditions.

Introduction. One of the promising areas for the development of construction materials is to use carbonated materials with a low magnesium oxide content as raw materials for the production of binders and the manufacture of materials based on them. The relevance of the application of fibreglass reinforcement is related to the need to significantly increase the physical and mechanical properties of fibreglass dolomite sheets from magnesia binder. The introduction of polypropylene fibres will improve bending performance of composite material, increase in-service crack resistance and reduce shrinkage during hardening. The aim of the study was to select the optimal fibre concentration and determine its influence on the physical and mechanical properties of glass fibre dolomite sheets.

Materials and methods. The materials studied are glass dolomite sheets obtained by mixing burned dolomite, water solution of magnesium chloride, additives and fibrous reinforcement. The mechanical activation of the caustic dolomite was produced in a vortex layer device. The structure of the composite and the surface morphology were investigated by electron microscopic analysis. The influence of fibre parameters on the strength of the reinforced sheet was evaluated by a designed calculation model in the Ansys software complex.

Results. The results of the dependence of bending strength and specimen density on by concentration, length of polypropylene fibres are presented. The limit values of the stresses when bending, vertical movements of the unreinforced sheet, reinforced by fibres on the non-activated and mechanical activated binder are determined. A plasticity index for comparing the plastic deformations of the material was introduced and the value of fibre adhesion to the matrix was calculated.

Conclusions. It was established that the mechanical treatment of magnesium binder in a vortex layer device increases bending and residual strength, increases impact force, and the introduction of fibre prevents brittle fracture of the specimen.

Introduction. The paper is devoted to the problems of the current system of training specialists for the housing and communal services (HCS) sector and emphasizes the influence of the name of the educational program on its attractiveness. The authors note that the abbreviation “HCS” causes negative associations, reducing the interest of applicants.

Materials and methods. The presented material demonstrates an analysis of the labor market in HCS and the regulatory framework governing the operation of buildings, structures, and facilities; educational standards, as well as the specifics of the economic nature of construction and operation of buildings and structures. Monitoring, comparison, analysis, and synthesis of information methods are used.

Results. The authors identify a growing need for engineering personnel for the operation of capital construction facilities and emphasize the differences in the training of specialists for construction and operation. The necessity of separating “Operation of Buildings and Structures” as an independent direction in the All-Russian Classifier of Economic Activities (OKVED) is substantiated. The problem of changes in the Federal State Educational Standard “16 Construction and Housing and Communal Services” is also indicated.

Conclusions. The paper proposes concrete steps to modernize the personnel training system, including changes in educational standards, the name of educational programs, and the creation of a system for monitoring staffing in HCS. It is proposed to amend the OKVED and OKZ. The necessity of developing “Rules of Operation…” for more than 30 types of buildings, structures and facilities is emphasized. These measures, according to the authors, will improve the quality of specialist training and their competitiveness in the labor market.

Introduction. Optimization of water-cement suspension composition for jet grouting in hydraulic engineering construction is an urgent task due to insufficient knowledge of how cement slurry composition affects soil-cement properties under constant water saturation, as well as limitations in applying this technology in this construction sector due to specific loads and aggressive environmental impacts. The study aims to determine the optimal water-cement suspension composition ensuring high physical and mechanical characteristics of soil-cement. The main tasks included field and laboratory testing of compositions with various additives and water-cement ratios.

Materials and methods. The research programme involved constructing 15 soil-cement columns with 5 different compositions, followed by sampling of soil-cement specimens for laboratory analysis of their strength, deformation modulus, and density. The tests were conducted under complex geological and hydrological conditions.

Results. The highest unconfined compressive strength and deformation modulus were recorded for the composition with a water-cement ratio of 0.8. Chemical additives (sodium silicate and technical soda) did not show significant improvement in characteristics, with strength increase amounting to only 1–9 %. An unexpected result was the strength reduction observed when using both additives simultaneously. The soil-cement density remained similar for all compositions.

Conclusions. The best results were achieved with a water-cement ratio of 0.8, and this particular composition is recommended for practical application of jet grouting in hydraulic engineering construction. The obtained data on soil-cement characteristics confirm the effectiveness of jet grouting technology (JGT) in challenging conditions, while also demonstrating the need for preliminary experimental work to select the optimal composition.

Introduction. The paper examines the labour potential (LP) of workers in Russian construction materials industry (CMI) organizations. The relevance of the study is due to the specifics of the industry: a high share of physical labour, dependence on the health of workers, demographic aging of personnel and regional disproportions. The purpose of the work is to systematize and analyze existing scientific approaches to the study of the labour potential of workers, with an emphasis on its role in ensuring the sustainable development of Russian CMI organizations.

Materials and methods. A set of qualitative methods was used: systematic review, content analysis, comparative analysis, synthesis and structuring of publications by thematic groups. The selected publications examine the features of LP, human resource management, personnel, productivity factors and sustainable development, primarily in the CMI of Russia.

Results. The specificity of LP in the CMI of Russia was identified, consisting of the dominance of physical labour, a shortage of mid-level specialists with an excess of low-skilled operations, a high proportion of older workers, a shortage of young people, and an insufficient number of programmes for adapting working conditions for older workers.

Conclusions. The LP of workers is a strategic resource for the sustainability of the CMI, the implementation of which requires the development of a standard for assessing LP, the “Digital Personnel of the CMI” programme with an emphasis on retraining workers of older age groups, the introduction of “silver” mentoring and tax incentives for enterprises investing in ergonomics and reducing occupational hazards.