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Vol 17, No 2 (2018)
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https://doi.org/10.21122/2227-1031-2018-17-2

CIVIL AND INDUSTRIAL ENGINEERING

91-94 881
Abstract

Operating experience of concrete with vigorous motion of heavy vehicles has shown that, despite the high strength concrete slabs themselves, they need a strong base. When concrete is close to the ground in it, as a result pushes elastically flex when the aisles plates vehicles accumulated residual deformation. Initially, under the plates formed cavity plate lose contact with the ground, and then these cracks. The increase in base strength increases the cost of the pavement. In this paper,
a static analysis of rectangular plate on two-layer elastic foundation in the traditional setting. As the base, taken homogeneous

soils, with the upper and lower layer in the form of half-spaces. Considered plate loading variant symmetrical about two axes from the calculated external load wheels. The calculation is performed by B. N. Zhemochkina using symbolic mathematics package. When this plate was divided into 72 rectangular portion in the center of which was placed vertical brace, through which the elastic plate contact with a base. The resulting statically indeterminate system, calculated by the method of mixed structural mechanics, where efforts were taken for unknown in vertical connections, as well as linear and two angular displacements inputted pinching plate along the axis of symmetry. Coefficients of the unknowns related efforts B. N. Zhemochkina determined by the method described previously by one of the authors. The calculation of the vertical plate prepared surface displacements reactive voltage across the contact plate and an elastic base. The proposed approach can be used to find the optimal solutions to (sufficiently) base strength to the estimated vehicle as well as for calculations hinged precast concrete plates.

 

95-99 905
Abstract

Disadvantages of road concrete pavement quite well known professionals-standards. They were mainly low elasticity modulus asphaltic concrete, as well as a fairly rapid aging of asphalt concrete core component-bitumen. And, as a consequence, is relatively low durability of the coating, the need for frequent repair. To some extent, cement concrete cover signifi cantly outperform this index of asphalt, convinces experience roads of Germany, the United States and other countries. The correct structure of concrete, overall compliance technology laying concrete, comprehensive quality control production  work, sufficient technical personnel qualifications provide long defect-free work road re-coated. However, violations by manufacture of works or in the process of exploitation, particularly in the harsh conditions of freezing and thawing, saturation-drying, especially under the influence of salts-defrosting, cause defects, reduce its durability. There are two directions of increase of durability of the coating. Firstly, it is the primary protection is the creation of concrete with minimal possible on data components mixture water cement ratio that provides reception of concrete with minimum porosity and consequently with maximum durability. Secondly, the secondary protection, providing increased resistance already ready-mixed concrete cover external aggressive actions. In this case against the background of other ways quite promising looks impregnation of the surface concrete integrated structure. Composition must contain multiple components, primarily water repellents, preventing penetration of fluid into the body of the concrete, and finely dispersed silica sol in particular silica, providing reduction of the porosity of the surface layers of concrete by interacting with the free calcium hydroxide. The problem of optimization of impregnation structure and is dedicated to this work.

100-105 935
Abstract

Various types of protection are used in order to ensure rigidity in earth dam slopes and dumped rip-rap and precast and cast-in-situ reinforced plates are the most commonly used for this purpose. Durability and reliability of the protections mainly depend on the fact whether protection parameters have been correctly calculated and correspondingly observed during the process of protection creation, the main protection parameters are material diameter of dumped rip-rap and thickness of reinforced plates. Values of protection parameters calculated in accordance to the existing formulae significantly differ among themselves. Some of these formulae are acceptable for small water reservoirs in Belarus and provide actual results only for large water reservoirs where a wave height reaches two metres and even more. A new calculation methodology which is suitable for Belarusian water reservoirs of various size is proposed with the purpose to determine diameter of dumped rip-rap material and thickness of plates for earth dam slope protection in the zone of active wave impact. The methodology has been developed on the basis of the theory pertaining to limit equilibrium of slope shearing and holding forces. While calculating diameter of dumped rip-rap material the following shearing forces have been taken into account: uplift wave pres- sure depending on wave height; drag force which is formed on the slope due to back sweep of wave; shearing component of protection material gravity force which is dependent on preselected slope ratio. Holding forces are determined with due ac- count of main physical and mechanical properties of dumped rip-rap material: density of particles in water suspension, porosi- ty, internal friction and holding component of protection material gravity force. While developing methodology for calcula- tion of reinforced concrete plate thickness a drag force has not been taken into account because the flow which is formed on the plate surface does not exert an influence on their equilibrium. Bottom slope zone where hydrodynamic pressure is created by bottom velocity has usually a reduced-weight protection in the form of broken stone, gravel and finely broken stone rip-rap. Dependences for determination of dumped rip-rap fineness have been obtained as a result of slope rigidity criterion conversion. The proposed formulae for calculation of earth dam slope protection parameters can be recommended for applica- tion in design organizations.

106-113 963
Abstract

On the coast of the Russian Far East the climate is monsoon, which is most pro-nounced in the south and northeast waning. Seasonal change of oceanic and continental influence is reflected in the nature of the climate: summer is moderately

warm and rainy, winter is cold and snowy. On Sakhalin winters are less severe than on the mainland. In Kamchatka, where the winters are milder, the influence of the continental monsoon less. In the southern part of Primorye snow is so small that there is in the rivers spring flood. In the north of the Amur region, Sakhalin, Kamchatka rainfall and snowpack increases. In the summer is dominated by southeast wind, which spread to the continent moist Pacific air. During the year, between the Pacific Ocean and the south of the Far East there is an intensive exchange of air masses. Seasonal change of air currents is determined by the thermal contrast between the continent and the ocean. During the year passes over the area to an average of 100 cyclones (3–6 per month during the cold period, and up to 3 – warm), which are ac-companied by increased wind, cloudy weather with precipitation, and in late summer and early au-tumn, typhoons observed outputs. Typhoons are accompanied by stormy winds reaching speeds of over 40 m / sec. and heavy rains. A wide variety of observed in the distribution of precipitation. The Chukchi-Anadyr area for the warm period falls to 200–250 mm in the north of the Sea of Okhotsk – 400–500 mm, in intermountain basins up to 250–300 mm. To the south the amount of precipitation increases to 500 to 600 mm in the Amur region and 900–1000 mm on the western slopes of Sikhote Alin. In the course of the annual maximum rainfall in the second half of the summer, but there are rainy June and September. No wonder that in such conditions, corrosion, material of hydraulic structures is most intense. Concrete and cement stone reinforced concrete structures exposed to corrosive attack, particularly the aggressive action of CO2 common acid gas, which is to neutralize the surface layer of concrete and the formation of the compounds that affect its properties. The article discusses the impact of the environment model south of the Far East, mainly due to the impact on hydraulic reinforced concrete structures of carbon dioxide in the environment, with subsequent corrosion of concrete and reinforcement.

114-122 1784
Abstract

The Republic of Belarus possesses a limited number of important natural resources and their conservation is considered as one of the strategic directions for the development of construction industry. Regularities in resource saving can be used not only for cost-cutting at the expense of cheaper materials with worse properties but they can also be used under certain specific conditions for price formation through selection of expensive qualitative construction materials and products. Thus an analysis of changes in concrete price due to higher compressive strength has shown that the price per one concrete cubic metre is increasing much more slowly than an increase in strength. For this reason high-performance concrete is more advantageous in comparison with lowand medium-strength concrete. New comparative units for strength and other physical properties have been proposed for assessment of resource efficiency: unit price (in case of being used) and cost price (in case of being manufactured) make it possible to compare various materials and products and such approach is necessary while using steel tube confined concrete (STCC) structures in construction. Estimates suggest that high-strength concrete and tubes with minimum thickness of walls withstanding lateral pressure of a core which is deformed under load must be applied for STCC structures under normal operational conditions. In this context it is necessary to use damping devices for compensation of difference in characteristics of concrete and tube material and these devices ensure maximum safe load of concrete core and tube material.

123-129 1111
Abstract

As a city is a complex system, it complies with the principles pertaining to organization and management of systems. System analysis makes it possible to figure out the difference between managing systems (subject) from systems that are managed (object). There is a link between these system formations which unites them in a common system. Such relationship is a source of information for development of management action. Impact on the system is achieved through availability of influential means and data. Urban planning science represents a city as a complex of socio-economic, territorial-productive and demographic-ecological systems of the following type: “population” – “environment” – “activity”. “Environment” is thought of as a technical system with such synonyme notions as “urban planning system”, “anthropogenic environment”, “settlement system”. “Environment” has two components – territory and buildings. Ukrainian legislation determines that management of urban planning activities is carried out through developing urban planning documentation and carrying out urban planning monitoring. Results of the urban planning monitoring are taken into account while preparing urban planning documentation (introduction of amendments to it) and programs of socio-economic development. Thus, urban planning monitoring represents a management system of urban planning activity in the Ukraine. Legislation of the Republic of Belarus contains some provisions which regulate urban planning activity through urban development planning and zoning of territories; creation and maintenance of urban planning cadastre; control over development and implementation of urban planning, architectural and construction projects; implementation of state construction supervision. Data of the urban planning cadastre are taken into account in urban planning documentation. In comparison with the Ukraine management of the urban planning system in the Republic of Belarus is attached to the urban planning cadastre. The urban planning systems of the Ukraine and the Republic of Belarus are self-managed reflexive systems that organize their behavior with due account of not only the past experience but also due to possible impact of other system which is in interaction with it.

130-141 839
Abstract

An algorithm for assessment of level in engineering and infrastructure support of urban area has been developed while using geographic information systems (GIS) in the framework of stakeholder-integrated approach. In order to achieve the target goal the following tasks have been solved: description of stakeholder-integrated approach to assessment of level in engineering and infrastructure support of cities; systematization of the existing approaches to assessment of level in engineering and infrastructure support of cities; development of an algorithm for determination of data for spatial models; development of spatial models for assessment of level in engineering and infrastructure support while using geographic information systems. A comprehensive approach has been proposed to simulate spatial factors in order to assess urban engineering and infrastructure support, which is different from the existing ones due to development and application of GIS tools. Spatial models of urban engineering and infrastructure support have been developed in the paper. They include territorial, ecological, power engineering, socio-economic and other characteristics. These models have made it possible to implement the proposed approach for simulation of the spatial factors. It is necessary to point out the fact that geographic information systems have been used and this approach provides a possibility to detailed consideration of models which reveal influence of spatial factors. So it is possible to increase objectivity of solving the problem.

142-145 1006
Abstract

Chemical additives are widely used in the technology of concrete with the purpose to solve various problems and sulphate-containing additives-electrolytes are also used as accelerators for setting and hardening of cement. Action mechanism of additive accelerators for setting and hardening of cement is rather complicated and can not be considered as well-established. An influence of sulfate-containing additives such as sodium sulfate is reduced to acceleration of cement silicate phase hydration by increasing ionic strength of the solution. In addition to it, exchange reactions of anion additive with portlandite phase (Ca(OH)2) and aluminate phases of hardening cement have a significant effect on hardening process that lead to formation of readily soluble hydroxides and hardly soluble calcium salts. The influence of sulfate-containing additives on properties of water cement paste and cement stone is quite diverse and depends on salt concentration and cation type. For example, the action of the aluminum sulphate additive becomes more complicated if the additive is subjected to hydrolysis in water, which is aggravated in an alkaline medium of the water cement paste. Formation of hydrolysis products and their reaction with aluminate phases and cement portlandite lead to a significant acceleration of setting. Thus, despite the similarity of additives ensuring participation of anions in the exchange reactions, the mechanism of their influence on cement setting and hardening varies rather significantly. The present paper considers peculiar features concerning the mechanism of interaction of sodium and aluminum sulfate additives in cement compositions from the viewpoint of thermochemistry. Thermochemical equations for reactions of sulfate-containing additives with phases of hydrated cement clinker have been given in the paper. The paper contains description how to calculate thermal effects of chemical reactions and determine an influence of the formed products on the setting and hardening of Portland cement.

146-156 3266
Abstract

The paper considers large-panel constructive system of multi-storey buildings and its industrial basis creates conditions for intensive volume growth in house construction. Application of hollow-core panels are recommended as floor slabs that allows to increase a distance between bearing walls, to improve planning solutions, and also significantly to increase thermal and sound protection properties of floor discs (coatings). Keyed joints having the highest resistance to shearing forces are used to ensure joint action of the slabs with wall panels. A supporting unit of floor elements in the precast-monolithic constructive system ARKOS by means of concrete keys is considered as a prototype of the considered joint. In order to increase a bearing capacity and improve reliability of joints it is envisaged to reinforce keys with space frames. Improvement of joint units is possible to carry out with due account of total number of the factors influencing on strength. Poltava National Technical University named after Yuri Kondratyuk has developed a general methodology for assessment of bearing capacity in keyed joints which is based on the variational method in the theory of concrete plasticity and reflects specificity of stress-strain state of the failure zone. For experimental verification of this methodology investigations have been carried out with the purpose to test operation of keys when they are reinforced in mid-height and reinforcement is distributed in two tiers. The observed experimental fracture pattern in the specimens has confirmed kinematic schemes accepted for calculations and comparative analysis of experimental and theoretical values points to their closeness. Two-level reinforcement significantly improves plastic properties of concrete keys and excludes brittle failure. The proposed design of the joint unit for floor slabs with wall panels is characterized by the ratio of key dimensions and shape of reinforcing cages in the form of hollow cylinders which ensure higher strength and seismic resistance of a joint.

157-164 888
Abstract

The paper proposes and considers two constructive methods for saving heat energy while manufacturing vertical insulating glass units with various gas filling of inter-glass space. The first method presupposes manufacturing of insulating glass units having specific thickness which is calculated in accordance with specific features of convective heat exchange in the closed loop circuit. Value of the heat-exchange coefficient depends on gas properties which is filling a chamber capacity (coefficients of thermal conductivity, volumetric expansion, kinematic viscosity, thermometric conducivity), temperature difference on the boundary of interlayer and its thickness. It has been shown that while increasing thickness of gas layer convective heat exchange coefficient is initially decreasing up to specific value and then after insignificant increase it practically remains constant. In this connection optimum thicknesses of filled inter-layers for widely-spread gas in production (dry air, argon, krypton, xenon) and for carbon dioxide have determined in the paper. Manufacturing of insulating glass units with large thickness of gas chamber practically does not lead to an increase in resistance to heat transfer but it will increase gas consumption rate. The second industrial economic method is interrelated with application of carbon dioxide СО2 as a filler of inter-glass space which has some advantages in comparison with other gases (small cost due to abundance, nontoxicity, transparency for visual light and absorption of heat rays). Calculations have shown that application of carbon dioxide will make it possible to increase resistance to heat transfer of one-chamber glass unit by 0.05 m²×K/W (with emissivity factor of internal glass – 0.837) or by 0.16 m²×K/W (with emission factor – 0.1) in comparison with the glass unit where a chamber is filled with dry air.

NATURAL SCIENCES

165-172 1310
Abstract

The paper presents the results of a preliminary study on the structural analysis of the pelvic girdle, comparing results for the analysis performed before and after the hip replacement procedure with taking into account changes in the mechanical properties of the articular cartilage of the joint. Basic anatomy and biomechanics of the hip joint is introduced. The mechanical analysis of the hip joint model in each case is conducted. Final results of analysis are presented. The numerical model of the tested objects was made on the basis of CT and CAD modeling. Hip bone models were made using specialist software such as Materialise Mimics. The model is made in the program was then exported to a data exchange file in order to obtain the editable CAD files. Thus obtained models were the starting point for the implementation of the numerical model of personalized hip replacement. Numerical models of bone and implant were performed in Solidworks environment.

Mechanical analysis was carried out using finite element analysis. During performing of calculations with the use of finite element analysis other physical quantities are also being discretized: loads, tensions, restraints or other examples represented in the system with the use of continuous function. While performing the process of discretization software aims at maximally approximation of discreet and continuous form using approximation methods.



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ISSN 2227-1031 (Print)
ISSN 2414-0392 (Online)