Clement Khavkin, Iurii Kaliukh
Theoretical and applied issues of dynamic certification of the retaining wall in earthquake-prone regions of Ukraine
State Research Institute of Building Construction
Abstract. Technical maintenance and following certification of buildings and structures is a priority milestone to ensure the necessary and economically viable level of seismic resistance of construction projects in terms of moral and physical deterioration, seismic hazard refinement and further development of existing standards for design and construction in seismic regions of Ukraine. Certification of buildings and structures (BS) serve two main purposes: comparative assessment of the actual seismic stability of BS with refined seismic areas (definition of seismic resistance deficit BS); identification of the most earthquake-prone sites requiring priority amplification or conversion. The article examines the theoretical and methodological and practical issues of dynamic certification facilities of the retaining wall and drainage gallery in the city of Chernovtsy. Existing methods of certification can be divided into three groups: methods of expert assessments, computational and analytical methods, methods of technical diagnostics. By virtue of the above-described advantages and disadvantages inherent in each of the three approaches, methodological problems of certification can be reduced to two major problems. The first problem — it is the correct definition of the criterion in the evaluation of seismic stability of the surveyed buildings or structures: expert assessment, reflecting the degree of compliance with requirements of the design object DBN; settlement and analytical evaluation of seismic resistance, seismic loads corresponding conditional on DBN, the results of technical diagnostics BS. The second problem — the definition of the required level of exposure at which explores the dynamic structure of buildings: micro dynamic level during the elastic stage of construction or load level corresponding to the work of building structures beyond the elastic limit. Shown how to use the equipment may be carried seism metric analysis of free oscillations of small amplitude of BS get their dynamic characteristics: the main periods and forms of free oscillations, logarithmic decrement, etc. At the level of a single DBN or standard common method of dynamic certification today in Ukraine don’t exist now. For this reason, improving methods of examination to evaluate their actual seismic stability, including taking into account the physical deterioration of structures, is an urgent task. The analysis of free oscillations of BS can obtain the following dynamic characteristics: the main periods and forms of free vibrations of buildings and structures, the logarithmic decrement, etc. As a result of the dynamic certification of the retaining wall and drainage gallery in the city of Chernovtsy, necessary dynamic data had obtained. According to the results of the dynamic certification and technical survey prepared appropriate recommendations that have already taken into account by local authorities Chernovtsy for reconstruction projects and reconstruction of drainage gallery.
Keywords: free vibrations, certification, retaining wall.
Dmitriy Ostapenko
Convective heat transfer in the boiler tube with turbolators
Donbas National Academy of Civil Engineering and Architecture
Abstract. Boiler making is a strategic industry. Its development allows the state to solve the issue of economical use of fuel in all industries. Reliability and efficiency of the heat generating equipment, its operation without harm to the environment are key indicators of effective energy supply of the country. The main trend in the world progress in the municipal power system is to reduce the cost of fuel for generation of heat by increasing the coefficient of performance (COP) of boilers. One way to improve efficiency is to install the tubes turbulators in convective package. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat source of domestic production. The paper presents the experimental data of such a boiler, as well as theoretical studies to determine the characteristics that influence the heat transfer, depending on the degree of overlap of the channel cross section tubes with a turbulator in the form of a broken belt.
Keywords: heat transfer, convective tube, turbulator, the degree of overlap, temperature, turbulent viscosity, the heat transfer coefficient.
Anna Kondrykinskaya
A choice of ways of economy of fuel and improvement of ecological indexes are in the systems of heating
Donbas National Academy of Civil Engineering and Architecture
Abstract. Efficiency increase of heat energy generation by means of water heating boilers use with direct contact of flue gas and circulating heated water on mass and heat exchange bearer is grounded. The stay time of fuel burning products lessening in high temperature zone 0,3 sec and burning products by water dispersion cooling provides NOx emission reduction and heat exchange improvement. Condensation of steams of water on heat-exchange attachment of the probed condensation caldron increases the coefficient of heat emission from the products of combustion of fuel more than in 15 times. Analytical dependence degree of lowering NOx generation on the time the products of combustion in high temperature zone and excess air are defined. The investigation of water-heating condensation boilers shows that NOx and carbon oxide emission less then international indices.
Keywords: condensing water-heating boilers, packing, burning furnase, pollution emission, carbon oxide, NOx.
Aleksandr Osipov
Research and parameterization of the production conditions of work in the reconstruction of buildings and structures
Kiev National University of Construction and Architecture
Abstract. The article presents the fundamentals of the parameterization of production conditions of work in the reconstruction of buildings and structures, which are understood as a set of influencing factors determining the spatio-temporal parameters and limits the scope of work, and taken as a parameter, or other evidence that the combination of which determines that or other integral characteristics the scope of work — the category of space-time constraint and the category-level restrictions on the conditions and requirements of the environment. Categories are defined relevant features (parameters) with coordinates (parameter value). The joint combination of formal attributes, categories of spatial-temporal constraint categories and levels of restrictions on the conditions and requirements of the environment, describes the (formalized) system property — the level of complexity of the conditions of the work. There are three categories of production conditions of work: moderate difficulty (I category), complex (II category) are very complex (III category).
Keywords: parameterization, the conditions of production work, grading, reconstruction.
Vladimir Scherba, Alexander Shishkin, Alexandra Shishkina
Research and parameterization of the production conditions of work in the reconstruction of buildings and structures
Krivoy Rog National University
Abstract. The results of studies on the fine-grained concrete modified gypsum cement binder and agreggate of continuous particle size distribution have been given. It has been proved that the introduction of the gypsum-cement binder cullet and salts of unsaturated fatty acids or polyhydric alcohol leads to a modification of its structure, resulting in a change in the structure and mineralogical composition of the stone binder. As a modification of gypsum cement binder and the use of a continuous particle size distribution of the agreggate in the preparation of fine grained gypsum cement concretes modified binder increases the strength and water resistance of the concrete part. Agreggate with continuous particle size distribution obtained by mixing quartz sand tailings iron ores. Cumulative effect of modifications flabby gypsum cement – binder salts of unsaturated fatty acids or polyhydric alcohol and use of continuous particle size distribution of the aggregate exceeds the effect of each factor is applied independently.
Keywords: fine concrete, strength, filler, salt, alcohol.
Alexander Shkurupiy, Pavel Mitrofanov
Definition of carrying capacity of concrete columns based on different deformation techniques
Poltava National Technical University named after Yuri Kondratyuk
Abstract. This article analyzes the methods of calculating the bearing capacity of reinforced concrete columns subjected to central and eccentric compression, based on the methodologies (deformation models) Eurocode 2, DBN V.2.6-98:2009 and the deformation model (DM) based on extreme strength criterion (ESC). Depending on the nature of the criterion of normal section strength, distinguish DM with empirical criterion of strength and DM with extreme (optimization) strength criterion. The most common are DM with empirical strength criterion, which also differ significantly, for example DM adopted standards Eurocode 2, DBN V.2.6-98:2009 and SP 63.1330.2012 (updated edition SNiP 52-01-2003). DM allows determining more precisely the boundary re-reinforcement strength or bearing capacity and parameters stress-strain state (SSS) concrete structures and their elements, and considering the nature of comprehesive diagrams for concrete and reinforcement. Existing DM, except DM with ESC need experimental determination of the ultimate strain compressed concrete parameters for the calculation of SSS in limiting stage. Shows comparative calculations of bearing capacity of reinforced concrete columns, calculated according to the methods mentioned above standarts, as well as the results determine their SSS limiting step procedure based on the ESC. It is proved, that the results of calculations of bearing capacity of compressed concrete columns based on DM with ESC more accurately coincide with the experimental data in comparison with the DM of the above standarts.
Keywords: concrete, reinforcement, strength, bearing capacity, reinforced concrete column, the maximum deformation, deformation model, extreme criterion, normal section.
Vladimir Yegorchenkov а, Yevgeniy Konopatskiy а, Irina Koschavka b
Non-uniform distribution of scanning points at calculation of natural lighting for light openings with different configuration
a Donbas National Academy of Civil Engineering and Architecture,
b Donetsk national university of economics and trade named after Mykhailo Tugan-Baranovsky
Abstract. Using mathematical apparatus of dot calculation by Baliuba-Naydysh (BN-calculation), the paper presents a method to scan light openings with different configuration that allows controlling the density of non-uniform distribution of scanning points in two directions along the plane of light openings’ inlets according to necessary conditions for numerical experiment. The necessary point equations for square and parabolic window are received in this paper, the computational algorithm to define the scanning points of window openings with different configuration in both directions is suggested, the graphical realization of the computational algorithm in Mathcad environment, suggested in the paper, is presented. By means of the received analytical model of scanning it is possible to optimize the consumption of the PC computing resources and reduce the calculation time of the field parameters. The offered way is universal as it can be used for forming not only a plurality of dot light but also wind, heat, radiation, chemical and any other flows.
Keywords: light flow, BN-calculation, simplex, scanning points, parabolic and square light opening, point equation.
Volodymyr Korsun, Andrii Niedoriezov, Sergey Makarenko
Comparative analysis of the strength criteria for concrete
Donbas National Academy of Civil Engineering and Architecture
Abstract. The results of comparing calculations of the concrete strength on the most developed failure criteria are presented. The basic relations for failure criteria of G. A. Geniev, G. A. Geniev – N. M. Alikova, E. S. Leites, A. V. Yashin, S. F. Klovanich – D. I. Bezushko and K. J. Willam – E. P. Warnke are described. The evaluation of the compliance of the calculated values with test data at one-, two- and triaxial stress states are performed. The failure criteria for concrete, most closely described the experimental data in specific areas of stress state, are evaluated. It is found that the most developed are the criteria of S. F. Klovanich – D. I. Bezushko and K. J. Willam – E. P. Warnke. E. S. Leites and A. V. Yashin criterion correspond quite well with experimental data at biaxial stress state. Criteria of G. A. Geniev and G. A. Geniev – N. M. Alikova require cautious use in accordance with their deviations from the experimental data in individual areas of complex stress state. Loading programs for experimental studies of concrete strength to more accurately identification of the forms of the functions of deviator curves are determined.
Keywords: concrete, volume stress state, strength, limit surface, strength criteria, meredian curve, deviatoric curve.
Myron Gogol
Calculation and rational design combined metal structures
National University «Lviv Politechnique»
Abstract. The article deals with the issue of rational choice study estimated geometrical parameters of the combined metal structures and analysis of the results of research. The use of these structures presents a major opportunity to create surfaces that are easy, high technical-economic indicators, architectural expression. Using the calculation method of adjustment of SDS combined metal construction ensures equality of stresses in the calculated cross section of the beam stiffness. It is shown that rational combination design as a whole depends on the stiffness of the suspension towers supporting system and the topology. It is proved that the mass of continuous beam stiffness at intermediate elastic supports, compared with a beam on two supports to span 60 m, rapidly decreases in the presence of up to three towers. Rational angles podkosov, strands and cables composite structures relative to their weight in the range of 30–60°. The research results are put into practice building, bringing economic benefit was obtained 6 118 thousand uah.
Keywords: rational combination design, equi-stress, suspension towers, regulation, rational angles.