Construction: science and education

Introduction. The paper deals with relaxation and creep coefficients, long-term ultimate bending deformation under long-term exposure to moisture and chemically active environment (10,000 hours) of sewer pipes.Materials and methods. 400, 1,200 and 1,400 mm diameter sewer pipes made of glass-reinforced polyester. A compressive load was applied to the specimen at a constant rate until a specific annular strain of (3.0 ± 0.5) % was achieved in (60 ± 10) s. The obtained specific annular strain was kept constant for 2 minutes, after this time the compressive load and annular strain were determined and recorded. The essence of the method is to load a test specimen, placed horizontally and immersed in water, at a given temperature, with a diametrically compressive load for a time during which the annular strain remains constant. The load is measured at specified intervals until 10,000 h is reached. According to the test results, the long-term specific annular stiffness and relaxation coefficient under the influence of moisture are determined in accordance with the methodology of GOST R 57008–2016. Two specimens shall be used for testing, unless otherwise specified in the normative document. Long-term specific ring stiffness and relaxation coefficient are the arithmetic mean obtained for two specimens.Results. It was found that the performance characteristics (long-term ultimate bending deformation, relaxation and creep coefficients when exposed to moisture) of the investigated sewer pipes are determined by the specific ring stiffness and their diameter. For polyester pipes with initial ring stiffness of 5,000 N/m2 increasing their diameter from 400 to 1,400 mm leads to linear increase of relaxation coefficient (from 0.79 to 0.96) and decrease of long-term ultimate bending strain (from 0.84 to 0.75 %) when exposed to moisture during 10,000 hours.Conclusions. The durability of the investigated sewer pipes made of glass-reinforced polyester exceeds 50 years.

Introduction. The current practice of pile foundation selection is a time-consuming, incoherent and non-standardized process. The aim of the study is to develop a methodology for optimizing structural calculations on the example of a pile field, based on cone penetration test data. For this purpose it is necessary: to prepare an algorithm for processing data from engineering-geological surveys; to develop a strictly deterministic process of justification of the best option depending on the cost of the pile foundation; to obtain a visual representation of the data for the possibility of verification of the selected solution.Materials and methods. A genetic algorithm is used to optimize structural calculations of the pile field, which is implemented using the Galapagos plug-in based on the Grasshopper visual programming language. Python programming language is used to prepare initial data of geotechnical engineering surveys.Results. Linked algorithms for cone penetration test data processing and preliminary estimation of the optimal pile foundation configuration based on its total cost, on the bearing capacity of the pile foundation soil were developed.Conclusions. The developed algorithms can be used for preliminary calculation and rapid evaluation of pile foundation options. The required input data can be generated from calculation programmes. Alternatively, selection and optimization can be performed directly in Python code, using Grasshopper and Rhino only for force extraction and subsequent visualization of the results. Areas for further research and development include: consideration of layered geotechnical elements; estimation of the bearing capacity of each foundation footing independently and according to the underlying geotechnical elements; grouping of piles according to their position in the pile field and loads; consideration of the non-linear behaviour of the soil mass.

Introduction. The development of methods for determining the frequencies and forms of vibrations, as well as dynamic reactions of thin slabs with different support systems, including those supported on point supports, is an urgent task, the solution of which is the subject of this paper.The aim of the work is to develop experimental methods for determining the frequencies and forms of natural vibrations of thin point-supported square solid slabs and slabs with holes.Materials and methods. The methodology and analysis of experimental results of dynamic characteristics of square solid slabs and slabs with holes are presented.Results. In this work, the frequencies of natural vibrations of square slabs with free edges resting on point supports are determined; the dependences of frequencies of slabs vibrations on coordinates of point supports and sizes of symmetrically located holes are obtained; the location of point supports at which the fundamental frequency of slabs free vibrations is maximum, is determined; frequencies, forms and decrements of vibrations of square slabs resting on four point supports are experimentally determined, as well as the influence of presence of holes and the degree of pinching of the supports on the dynamic characteristics of these slabs.Conclusions. Comparison of experimental and theoretical values of natural vibration frequencies of the slabs showed good similarity. The results obtained in this paper can be appplied to dynamic and seismic calculations of point-supported square slab coverings.

Introduction. The software complex of building information modelling (BIM) RENGA today is gaining popularity among various users in the field of design of construction objects. As any software product, RENGA has its advantages, disadvantages and perspective directions for development. At the same time in Russia the concept of modular design and construction is spreading, for the implementation of which a certain functionality of information modelling is necessary. Consequently, it is expedient to study the functionality of the Russian software complex of information modelling RENGA within the framework of modular design tasks. The purpose of this paper is to analyze the means of assembling and combining primitives of the information model to create modules in RENGA, and the tasks are: to determine the criteria for comparing software complexes, to develop a BIM-module based on the available functionality and to analyze the practical capabilities and functionality of RENGA.Materials and methods. The implementation of this research is based on the method of synthesis of design processes and their automation, as well as the analysis of Russian and foreign experience in the field of modular design. At the same time, the process of BIM-module development within the framework of programme capabilities of the RENGA programme is considered.Results. The result presents a comparative analysis of the software capabilities of the RENGA information modelling software package for the development of the BIM-module and its further implementation in the complex information model of the object. To carry out the analysis the basic functions of module design of foreign software tools of information modelling were determined. The author has carried out practical use of RENGA toolkit for development and use of BIM-modules.Conclusions. The presented analysis of means of grouping elements for the development of BIM-modules in RENGA demonstrates the available tools for solving the problems of modular design, the peculiarities of their implementation, the complexity of functioning and shows the lack of certain tools for the most complete work. Simultaneously by results of direct development of BIM-modules in RENGA, the peculiarities of design within the framework of modularity are presented, basic drawbacks and directions for further development and increase of efficiency of modular design are formulated.

Introduction. The total capacity of power plants and the length of power grids in the Russian Federation are significantly increasing every decade due to the constant industrial development of cities and suburbs. This requires the involvement of huge material and labour resources in the sphere of power construction, so all possible ways to reduce the capital intensity of power grids of high and ultra-high voltage classes should be identified and implemented. For practical purposes, in addition to solving the stability problem itself, it is necessary to determine the combination of external loads (torque and longitudinal force) that predetermines the smallest possible value of the critical parameter.Materials and methods. Due to the different lengths of the individual struts of the supports and the increasing forces in the girdles towards the base, the degree of pliability of the nodes to linear and angular displacements is not the same, so that only some struts lose stability. The paper considers a square-section tower with parallel rather than inclined girders, in which the lattice and girders have the same cross-sections, respectively, and an increasing torque and an unchanged longitudinal force applied with respect to the vertical axis of the support act on its free end. Due to the symmetry of the system and internal forces at the moment of loss of stability there will be a symmetric deformation of the struts losing stability. The problem was solved using the system of canonical equations of the displacement method in numerical and analytical formulation. The application of the described methodology for determining the design lengths of the grid struts is considered on the example of the lower section of the support 1P330-1.Results. The considered fragment of the support in terms of structural solution is a spatial rod steel column, the nodes of which are not aligned in adjacent faces and consists of 12 panels. The structural elements of the section are bars made of single angles. The joints are bolted together. The canonical coefficients for the struts of each panel are determined and the stability equation is solved graphically, from which the design length coefficients are found.Conclusions. The presented numerical and analytical method allows to determine the coefficients of design lengths of tower support shaft elements depending on the longitudinal force and the ratio of chord and strut stiffnesses. The obtained coefficients are approximately 10–15 % lower than the existing ones in the domestic standards. As a result, the reserve of bearing capacity of supports is revealed, which indicates the possibility of improving the methodology of solving the problem of stability of elements.

Introduction. The subject of the study is suffusion — an exogenous geological process dangerous for construction, capable to cause a catastrophe. The term suffosion is interpreted most widely in comparison with other interpretations: according it suffosion includes leaching, piping, subsurface erosion of soils or rocks, cemented by soluble material. The aim of the study is to analyze the interaction of natural and anthropogenic subsystems in natural-technical systems arising from the economic development of territories favourable for the development of suffosion processes.Materials and methods. Domestic and foreign experience of exploitation of objects of various purposes experiencing negative impact of natural and anthropogenic suffosion processes is analyzed from the position of system approach. Special attention is paid to possible catastrophic consequences of such impacts for buildings and structures. It is noted that, despite the presence of certain positive aspects in the interaction of suffosion with the environment, negative aspects prevail.Results. Neutralization of possible undesirable social and ecological consequences of formation of various kinds of underground and surface suffosion manifestations is achieved by rational choice, clear engineering-geological substantiation and competent implementation of measures that sharply reduce (and sometimes exclude) the possibility of related emergencies. Classification of currently used and quite suitable for application in the future methods of protection of territories, buildings and structures from negative consequences of suffosion development, including those provoked by the protected object itself, is proposed. Different variants of protective measures related to each of the identified types of anti-suffosion measures are mentioned.Conclusions. It is noted that in the presence of existing suffosion occurrences on a particular territory or in case of a scientifically justified assumption regarding the potential possibility of development of suffosion processes, a comprehensive assessment of the natural-technogenic situation and its expected changes is necessary. This should be followed by planning of further actions, either to preserve the landscape elements formed by suffosion or to eliminate any threats from this process as much as possible.

Introduction. At the present stage it is becoming important to take into account the category of environmental toxicity (ecotoxicity) in the life cycle assessment of building materials in accordance with the methodology of international standards ISO 14000 series. Among the methods of ecotoxicity assessment, two groups can be distinguished. The first includes tests using living organisms (freshwater unicellular algae, crustaceans Daphnia magna Straus, fish embryos and luminous bacteria), standardized at the international level. Moreover, there are specifics of their application for different materials: for slab and film materials - dynamic leaching test, and for granular materials - percolation. It is important not only to study ecotoxicity for water, but also for soil. The level of microbial biomass activity and phytotoxicity of soils become important soil parameters in this respect. The second group of methods includes ecotoxicity calculations in the Comparative Toxic Unit, CTUe. Studies were carried out for building materials from different groups by the type of basic raw materials, which gave results related to the correlation of data on water and soil. The adequacy of the tests and calculations was confirmed by comparison with the studies of foreign specialists already available for a number of materials. From the obtained data it is possible to draw conclusions about the application of ecotoxicity testing methods as additional methods in the assessment of construction materials, since only in the case of biological indication it is possible to proceed to the establishment of specific toxins by chemical-analytical methods. Proposals are also made to improve the regulatory legal framework in the field of ecotoxicity determination in the life cycle assessment of construction materials.The subject of the study is ecological toxicity indicators of building materials of different nomenclature and methods of their determination. Several methods of ecotoxicity testing as well as calculation of the indicator within the framework of life cycle assessment of building materials are considered. The study of ecotoxicity category indicators will improve the quality of life cycle assessment of building materials.Materials and methods. Comparison of methods for determining ecological toxicity, both in terms of testing on living organisms (both domestic and international standards), as well as in terms of calculations of toxicity indicators for humans and ecotoxicity was carried out. A research scheme was developed in which ecotoxicity becomes a key indicator for further studies of the characteristics of natural-technogenic systems.Results. A study was carried out in which ecotoxicity was determined for the same materials by tests in the aquatic environment as well as soil samples from sites associated with the life cycle of the materials. In addition, the calculated ecotoxicity values were analyzed and compared with studies by others. The adequacy of the results obtained was confirmed.Conclusions. Advantages and disadvantages of different methods of ecotoxicity determination are analyzed, assumptions are made about possible correlation of the results with the data obtained in studies of natural-technogenic systems. Proposals for improvement of the regulatory framework in the field of ecotoxicity determination and directions for further research are made.