Vol. 21, Number 2, 2015

Yaroslav Nazim, Anton Tanasoglo
Investigation of stress-strain state of supports structures of large crossing of intersystem transmission line at reconstruction with replacement of conductors 
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article deals with the stress-strain state of the structural elements of large transmission line crossing 154 kV «Kremenchuk Hydroelectric Station – Kremenchuk Heat and Power Station» across the river Dnipro under reconstruction with replacement of conductors (with a comparison of two types of conductors – ACSR and АААС Aero-Z). Calculations have been performed by means of developed software package, which is based on the digital and analytic methods of definition of stresses and deformations in element of structures of OPTL as part of common system. That allowed defining numerical value of loads from the conductor line and overhead ground-wire cables in a normal and emergency mode of operation on the structures of overhead power transmission lines, as well as stresses and efforts in the most stresses elements of supports. As a result of the calculation performed during the reconstruction of the local strengthening of structures of transition supports. The reconstruction has improved the reliability of power supply circuits in Kremenchuk due to increase of imparted electrical power without replacing the existing supports.
Keywords: overhead power transmission line (PTL), large transmission line crossing, tower, reconstruction, stress-strain state, software package.

Igor Garanzha
Research experimental complex of the stress-strain state of metal polygonal poles 
Donbas National Academy of Civil Engineering and Architecture
Abstract. An experimental research complex of metal multifaceted poles’ (MMP) stress-strain state (SSS) is performed in two stages: the research of six natural structural of MMP with high H=7.5 и 10.5 m at the DonNACEA Tower Testing Station and a SSS laboratory studying of fragments natural structures of metal multifaceted poles. The purpose of experimental research at the 1st stage is to identify specific zones of poles’ probable destruction and deformability, at the 2nd stage – (considering to the first stage’s results) is determination the structure’s stress-strain state at the joint work of the octagonal pole’s fragment, and its base, and also verification of convergence results with theoretical assumptions. For the research we used the load tests method and the tensometry method of determining the stress strain in the structural body. Tests of natural structures performed according to a pre-designed program. For laboratory researches the special experimental stand has been designed. Ultimately determine the sufficient convergence of numerical and experimental studies’ results of the multifaceted poles’ SSS. So, the adequacy of finite element computational model for use in an engineering design has been confirmed.
Keywords: metal polygonal poles, experimental researches, tower test station, testing hall, stress-strain state, nature structures, experimental models, tensometry.

Anton Makhinko a, Natalia Makhinko b
The calibration rationale for combination factors dead load, snow and wind loads in design of steel structures with DSTU-N B EN 1990
a Building company «Etual», b Poltava National Technical Yuri Kondratyuk University
Abstract. The article deals with calibration rationale for safety factors and combinations for dead load, wind and snow loads. The problem of combination of constant load and couple of temporary loads has been represented. The evaluation model of characteristics of temporary loads, the models of snow and wind loads and their combinations, which based on working results of V. A. Pshinski, have been given. The existing rules of effects combinations during calculation of constructions according to the first group of extreme limit state have been given. Calibration values of safety factors and combinations has been carried out involving probabilistic methods for reliability analysis of structures taking into account stochastic properties of external influences. It has been found out that the first-order definable attitude to the loads combinations, which is used in Ukraine national construction regulation «Loads and influence», lead to lower estimation of reliability index, in spite of higher value of combination factor. The ways of solution according to guarantee of reliability indexes of constructions within the ambit of regulatory documents, have been suggested.
Keywords: variable loads, stochastic process, coefficient combinations, safety factor.

Yevgen Gorokhov, Volodymyr Vasylev, Eduard Lozinsky, Hanna Zubenko, Andrey Drozdov
Features of the flow around the wind flow of solids of revolution in construction air mechanics 
Donbas National Academy of Civil Engineering and Architecture
Abstract. This article presents an analysis of complex surface geometries of facades of buildings with which the designer has to face in determining the current wind load on them. The absence of methods for determining wind loads on buildings curved in the regulations has been found out. A variant of the consideration of the facades with smooth surface shape in the form of bodies of revolution has been suggested. The short analysis of the state of studying the issue past bodies of revolution in the world has been carried out. A mathematical model of the flow of the gas jet above the solid curved surface, which is the physical meaning of the effect Coanda, has been given. The possibility of using this effect in building aerodynamics, wind flow in the flow of nonlinear solid surfaces that will expand the field of knowledge influence the wind flow on the facades of non-linear forms, has been presented.
Keywords: a body of revolution, the Coanda effect, the non-linear surface of facades, construction air mechanics, aerodynamic loads.