Alla Butova, Eduard Lozinskiy, Valeriya Lozinskaya
Rational Parameters of Buildings that Increase the Energy Saving of Existing Residential Buildings when It is Compacted
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article considers, based on the theoretical and experimental studies, an important scientific and technical task to improve the engineering methodology for calculating heat losses in mass-construction buildings, taking into account the effect of wind on them when compacting buildings of various storeys in terms of determining the multiplicity of air exchange. The results of experimental studies in hydro – and wind tunnels are presented in order to obtain an experimentally reliable picture of the wind flow around a group of buildings. As a result of the conducted studies, the regularities between the distribution of wind pressure on the surfaces of civil buildings of mass construction (on the shell and at the exits of ventilation shafts) were revealed from the geometric parameters of the projected building. The obtained experimental data allowed us to identify the patterns of physical processes that occur when the building flows around and to assess the wind loads and the effects of the impact on the surrounding buildings.
Keywords: energy saving, pressure coefficient, perimeter building, similarity criteria, wind tunnel, hydrodynamic tube, boundary layer, flow visualization, Reynolds number.
Andrey Mironov, Dmitro Belyy, Vladimir Anishсhenkov, Alexander Volchkov
Creep of Concrete in Steel-Reinforced Concrete Slab Structures using Profiled Flooring
Donbas National Academy of Civil Engineering and Architecture
Abstract. The paper presents an analysis of the actual work on the creep of concrete in the composition of a steel-reinforced concrete slab using a fixed formwork made of profiled sheet with dimensions in the plan of 20,5 m under prolonged static load without installing additional hardening and anchoring. An analysis of the test was carried out, the ultimate goal of which was to identify the ability of the slab to work, as well as to investigate the behavior of concrete within the slab body. Real changes in time of such characteristics as deflections and arising stresses on the slab surfaces are determined. The suitability of the steel-reinforced concrete structure according to the groups of limiting states has been determined. A comparative analysis of the results obtained with the data of regulatory documents has been carried out. Conclusions are made on the bearing and deformation capabilities of the structure under study under long-term static loading.
Keywords: experiment, slab, concrete, creep, load, efforts, deflection, stress.
Yevgen Gorokhov a, Volodymyr Vasylev a, Valery Gavrilov b, Аnton Tanasoglo a, Roman Ignatenko a
Influence of Geometric Imperfections of the Corners on the Load-Bearing Capacity of the Rack Belt of the Power Line Support
a Donbas National Academy of Civil Engineering and Architecture, b LLC «GPK ENGINEERING»
Abstract. In this article, we systematize and investigate possible geometric imperfections of equal-field corners that affect the strength and load-bearing capacity of the belt of metal lattice tower supports of power lines at the junction. The analysis of the degree of influence of factors of geometric imperfections for various types of bolted connection of the corners of the support chord is carried out. A numerical experiment was performed to calculate the dependence of the bearing capacity of the support chord corner in the butt joint on various factors. A program was used to recalculate efforts taking into account possible deviations: tolerances in the width and length of the angle flange; wall thickness tolerances of the corner; smoothing the edges of the corner; grind the edges of the corner. Using the regression equation with the calculated coefficients, a set of values of the longitudinal force N arising in the belt for any combination of these factors was obtained. A numerical experiment was carried out for real structures based on actual data. Recommendations are proposed for manufacturers, which consist in the mandatory implementation of the input control of the minus tolerance of the corner thickness (–dt= 1,2 mm maximum value) at the manufacturing stage.
Keywords: overhead power line (OHL), metal support, bolted connection, regression analysis; factors of influence, coefficients of significance of factors.
Volodymyr Mushchanov a, Yuliya Syvokon b, Margarita Kashchenko a,
Vadim Kasimov b
On the Issue of Accounting for Additional Stresses that Occur in Thin-Walled Profiles when Bending with Torsion
a Donbas National Academy of Civil Engineering and Architecture, b Nizhny Novgorod University of Architecture and Civil Engineering
Abstract. This article analyzes the account of the effect of thinness on the magnitude of normal and tangential stresses when modeling the design scheme of a cantilever beam with a cross-section in the form of an I-beam or channel with a loaded concentrated force in 2 versions: with eccentricity and without eccentricity relative to the center of the bend. The analysis of the components of the stress-strain state of the studied schemes was carried out on the basis of 2 calculation methods: analytical – within the framework of the main hypotheses of the theory of V. Z. Vlasov, and on the basis of detailed finite element modeling with shell elements using the capabilities of the LIRA-SAPR 2018 software package. The conclusions about the influence of the warping of the section on its stress state are obtained; the accuracy of the analytical method of calculation is assessed, as well as the rationality of the finite element modeling of such sections when solving such problems.
Keywords: thin-walled element, stress-strain state, bimoment, normal and shear stresses, finite element method.