Introduction.

The co-authors present the findings of experimental studies of the adhesion force arising between a zinc-coated steel plate and concrete. Four specimens were used in testing. Rectangular plates, embedded in a concrete parallelepiped, had different types of surfaces. They were smooth, perforated with holes, or they had connecting elements such as bolts or spikes. The behavior of specimens under loading is analyzed; graphs, describing the dependency between displacements and loading are provided, and the design resistance is determined to analyze the adhesion force between concrete and a zinc-coated steel plate.

Materials and methods.

Four specimens were used in testing. Each specimen represented a zinc-coated steel plate embedded in a concrete parallelepiped. A test bench, consisting of a load frame and a hydraulic cylinder, which pulled the steel plate out of a concrete parallelepiped, was used in the experiment.

Results.

Deformation dependences of specimens were obtained, graphs describing the dependence of displacement on loading were drawn for four types of surfaces, loading values that trigger the failure of specimens and dependence between the loading value, that triggers the failure, and the structure of the embedded part of the plate, are identified. The nature of the concrete failure at the interface with a zinc-coated plate is tracked.

Conclusions.

The results of the experiment enable us to conclude that the joint action of concrete and a steel beam is possible without the use of additional elements in composite structures that have bent profiles. The adhesion properties of materials and the stamped part of the profile are capable of absorbing shear forces arising in structures. For a more accurate analysis of floor slabs that contain bent profiles, additional experimental studies are to be conducted. Specimens, having bent profiles embedded in concrete, will be tested in the course of these experiments.

Introduction.

Currently, in all countries, Portland cement is used as a binder in the production of concrete, and its global production accounts for 10 % of the total carbon dioxide emitted into the atmosphere. Therefore, Portland cement can be partially or fully replaced by new cement-free binders, made of large-tonnage technogenic waste with a cementing effect, for example, by finely ground blast furnace slag, fly ash generated by thermal power plants and ash formed during the combustion of rice hulls. Aqueous alkaline solutions (NaOH and Na2SiO3 or KOH and K2SiO3) should be used as activators of setting and hardening of such binders, and calcium sulfate dihydrate can be used to adjust the setting time. Concrete containing new cement-free binders is called geopolymer concrete.

Materials and methods.

In order to reduce mixing water consumption and maintain the required workability of the fine-grained concrete mixture, a polycarboxylate superplasticizer was introduced into its composition. All raw materials, except for the superplasticizer, were of the Vietnamese origin. The following research methods were used: the composition of the geopolymer concrete mixture was analyzed using the absolute volume method, the workability of the concrete mixture was determined according to ASTM C1611-18 и TCVN 3106:2007, compressive and tensile strength of the concrete, subjected to bending, were tested pursuant to GOST 10180-2012, and the average density of concrete was tested according to GOST 12730.1-78.

Results.

The co-authors have developed the composition of the geopolymer concrete containing the alkaline cement-free binder. As a result of the heat treatment of the 28-days-old concrete for 6 hours at 100 °C, its compressive strength reaches about 60 MPa; hence, it can be used in the hot and humid climate of Vietnam.

Conclusions.

This cement-free concrete, in addition to its high strength, has good water resistance and low water absorption. This concrete has economic benefits, and its production will help to protect the environment due to the lower consumption of natural resources and the applicability of large-tonnage technogenic waste.

Introduction.

The air conditioning system is the main consumer of electricity inside office and shopping buildings. The cooling needs arise inside such buildings all over the year due to high amounts of heat emitted by people and equipment (computers, office equipment, cash registers), solar radiation (the envelopes of the majority of these buildings have continuous glazed facades) and sources of artificial lighting. A conventional cooling system has a compressor and condensers. The most important step towards an optimized and low-energy cooling system is the abandonment of compressor and condensers; in addition, the cold extracted from the outdoor air, is used in the system. This cooling technique is called an atmospheric cooling system. The climatic features of Russia allow for a large-scale application of the cooling technology that uses natural cold. However, for a start, a decision was made to focus on a central region of the Russian Federation, namely, Moscow, rather than any northern areas of the country.

Materials and methods.

The problem is solved by the calculation method applied to the case of a 35-storey office building in Moscow. Various outdoor temperature options were considered as the bases for a transition to an atmospheric cooling system. The co-authors also compare different installation options for dry coolers, which in turn affect the routing length of refrigeration circuits. The annual demand for cold is calculated for all analyzed options.

Results.

Some results are presented in the form of tables of annual energy consumption by different types of air cooling systems.

Conclusions.

The co-authors have found that the location of dry coolers strongly affects the power consumption by a cooling system. Power consumption by cooling systems was analyzed, and it was found out that transition to machine refrigeration at the higher outdoor temperature of +8 °C is more efficient from the standpoint of energy efficiency than the same transition at +5 and 0 °C.

Introduction.

Reservoirs are important elements of the water resources regulation system; they make a substantial contribution to regional economies. A multi-criterial approach to selection of the best locations for dams is proposed in the absence of exhaustive information on the quantitative assessment of individual criteria. Morphometric characteristics of retaining reservoirs are among the most important tools for analyzing water resources; they represent a quantitative study designated for the mathematical simulation of the most important characteristics of a reservoir and their linking to the indices and parameters that allow to find out the hydrological conditions. The purpose of the study is to select and rank the factors needed to determine the priority locations for the construction of hydraulic structures.

Materials and methods.

A critical analysis of the research works is carried out; the hydrological, geological, topographical aspects and land use factors are reasonably selected, which allow to propose a hierarchical decision-making model for prioritizing areas where hydraulic structures can be designed.

Results.

AHP-TOPSIS, a hybrid method of the multicriterial analysis, was used. A reasonable choice of parameters and other factors is necessary to make decisions needed to determine the best area that will accommodate construction works, since it will reduce the amount of pre-project work in a particular region. The reservoir, whose parameters and coefficients are studied, will be thoroughly explored with a focus on its hydrology, topography, geology, and terrain use. The municipality of Manicaragua, belonging to the province of Villa Clara, Cuba, is considered as a case of the practical application of this approach. Based on the information provided by the geographic information systems and the hybrid method of the multi-criterial analysis, a pairwise comparison of alternatives for each of the established parameters was performed, the weights of alternatives were obtained, and the order of prioritization of the areas that can accommodate hydraulic structures was established.

Conclusions.

The analysis of the priority areas, made on the basis of the selected parameters used as the criteria and alternatives, allowed us (1) to analyze 12,591 districts of the municipality of Manicaragua as the potential locations of hydraulic structures, and (2) to reduce their number to 23 %.

Introduction.

In the middle of the 20th century, technological progress made it possible to enlarge the building elements of buildings as much as possible, which led to the development of new industrial construction systems and increased production rates. However, to date, the issue has not been completely resolved and remains relevant. Modular construction is not sufficiently widely spread today, but many design experts predict its widespread introduction in the near future. The factor that decelerates the development of modular construction is the lack of theoretical foundations in the field of modular design, as well as significant differences from traditional design approach.

Materials and methods.

The purpose of this work is to develop the theoretical fundamentals of modular design based on the study of regulatory documents, Russian and foreign sources of research works, as well as the implemented projects. The task is to determine the fundamental features of modular elements of maximum readiness: principles of modular design, parameters of a modular element, advantages and disadvantages of a modular system, features of the design processes.

Results.

The theoretical basis of modular design includes basic concepts, principles and features; the conceptual design process is described using the case of development of an information model; parameters of modular elements of maximum readiness are presented, and the influence of modular items on the life cycle of a construction facility is analyzed.

Conclusions.

The presented system of principles of design based on modular elements of maximum readiness and parameters of modular elements allow us to systematize the established theoretical aspects of modularity, which make it possible to make modular buildings. The author formulates a new approach to design, which affects the entire life cycle and serves as the basis for new areas of engineering activities and scientific research.

Introduction.

The choice of the future profession, that determines the field of occupation, stages of continuous education, and routes to self-fulfillment, is a most important decision made in the course of a human life. The problem of choosing a career is not new, and it remains relevant at the present time. The purpose of the study is to identify the principal motives underlying career-related decisions, that make students choose the master programmes offered by NRU MGSU.

Materials and methods.

The methods, used by the co-authors, include interviews, didactic testing and observation of the process of its implementation by the students. The analysis and generalization of the empirical data, obtained in the course of didactic testing, have allowed to determine the principal motives underlying the choice of advanced master programmes provided by NRU MGSU.

Results.

Principal motives underlying the choice of master programmes, offered by NRU MGSU, include the prestige and popularity of professions in the construction industry; competitive compensation packages and career opportunities; satisfaction of educational needs, self-improvement and self-fulfillment; interest in computer systems and IT technologies; dynasties in the construction industry; willingness to serve the society and see the work results.

Conclusions.

Material and status-related motives have determined the choice of the master programmes delivered by NRU MGSU. This fact is explained by the development of research and practice, the upgrade of currently offered specialties and emergence of new ones, ensuring the advancement of the construction industry and allowing people to maintain their sufficiently high socio-economic status. The second important factor encompasses the motives that deal with the personality and his/her creativity and the motives that are associated with the satisfaction of educational needs, self-improvement and self-fulfillment. This factor substantiates the need to make schoolchildren think about their future profession as a self-fulfillment opportunity within the framework of vocational guidance procedures, and to encourage the manifestation of the need for continuous education, personal and professional development. A comprehensive analysis of motives can serve as the basis for improving the system of vocational guidance designated for schoolchildren and popularization of careers in the construction industry.