I.М. Lebedich, R.М. Pavlovsky, О.I. Zhdanov
Analysis of aerodynamic feature s of the over-stand roof in Dnepropetrovsk FC “Dnipro” stadium
Open Join-Stock Company «V.Shimanovsky Ukrainian Research and Design Institute of Steel Construction»National Aviation University, Aerodynamics and Airplane Operation Department
Abstract. The paper presents the results of the experimental study of the FC “Dnipro” Stadium models in Dnipropetrovs’k made on 1:300 and 1:120 scale in wind tunnels of the National Aviation University . Geometrical parameters modeling is carried out on the basis of the architectural silutions of Yu. Seryogin Design Bureau of the Ukrainian Community of Atchitects and the roofing design made by OJSC “V. Shimanovsky UkrRDIsteelconstruction”. A detrimental effect of of openings between the stands by the roofing plane to the wind loads on roofing is shown. The profiles of air flow static pressure roof on the upper and lower surfaces are given. The accuracy of wind loads on the roofs allows to decrease the specific metal amount of the stadium force framework by 10-15 per cent.
Keywords: stadium roofing , modeling, experimental study in wind tunnels, wind loads, aerodynamic features.
S.B. Pchel’nikov
Suarance of building structures maintainability
The Donbas National Academy of Civil Engineering and Architecture
Abstract. A model of the operational process based on using a probability of a no-failure operation is given in the article. A probability of a no-failure operation is used for estimating a technical state of separate elements, structures and a building as whole, as well as for forecasting a wear. When determining a probability of a no-failure operation of separate elements, the Monte Carlo method is used. A feature of the technique suggested is the use of a mixed distribution of stresses when determining a reserve of durability obtained by processing the data of the deterministic design of elements by the method of marginal states. A probability of a no-failure operation of separate structures and a building as whole is determined by the analysis of structural and technological connection of elements of these systems. Planning the measures of maintaining structures takes into account a variation of values of no-failure parameters when carrying out supervision measures. In the article the algorithm of determining the terms of conducting operational measures is offered taking into account a possible level of a no-failure operation. The result of optimizing the schedule of carrying out operational measures is a determination of an assured value of the probability of a no-failure operation of building structures during a given period of time at the set level of financing.
Keywords: building strictures, a no-failure operation, a schedule of operational measures, an admissible level of a no-failure operation.
Ye.V. Horokhov, V.M. Vasylev, V.I. Koval, A.M. Alyokhin
Boundary conditions for carrying out tests under conditions of artificial icing
The Donbas National Academy of Civil Engineering and Architecture
Abstract. The paper analyzes the similarity conditions for pickup factor simulation. There have been determined the similarity conditions while studying the cloud drops deposition from an air flow on similar bodies. The analysis has been done and the similarity parameters determining the conditions of a liquid water film existence and behavior on the surface-water or ice-water boundaries have been formulated. There have been examined the data on speed, height, and time of icing effect on a full-scale design and meteorological conditions affecting the structure. There have been derived a generalized equation for simulating the final ice thickness distribution within the pickup area, the system of equations in which the scale factors combinations obtained with the use of similarity conditions meet the requirements of the full-scale design. There have been obtained the scale factors depending on the wind velocity, a structure size under testing, kinematical air viscosity, the cloud spectrum diameter, test time under artificial icing conditions, drops quantity per the air volume unit, drops density in a unit of air volume. There have been also obtained parameters for full-scale and pipe tests a rational scheme for solving the system of equations (1.3).
Keywords: similarity, icing, power system, cloud drops, large-scale tests, pipe tests, scale factors, inertia criterion, the Strouhal number, the Nusselt number, a model.
A.М. Yugov, Ye.V. Denisov
Mаss variation technique for specifying parameters of the vibration method dynamic model
Donbas National Academy of Civil Engineering and Architecture
Abstract. It is often quite a multi factor task to determin e a stressed state of structures under operation. One of the methods that allow s solv ing this task for frame structures is the vibrati on method based on the dependence of natural lateral vibration frequency of a frame structure rod on a longitudinal force in it. The main idea of apply ing the vibrati on method is to determine the parameters of the accepted dynamic model – an effective rod length and the coefficient s of elastic fastening of boundary points. F or determining these parameters a technique of an additional loading and additional bonds were developed by the scientists of the Central Research Institute of Building structures in the 70-s of the last century. But these methods were not widely used because of the complexity of their in-situ application. The paper presents the basic theoretical principles of another technique for specifying parameters of the vibrati on method dynamic model , that is the mass variation method. That is the simplest method in terms of its practical application and it provides a sufficient accuracy of the vibrat ion method.
Keywords: a vibrat ion method, a dynamic model, a mass variation method.
V.M. Kuschenko
Application of dynamic tests for technical diagnostics of buinding structures of staying head frames
The Donbas National Academy of Civil Engineering and Architecture
Abstract. There is considered a possibility of using the results of dynamic tests for a technical diagnostics of building structures of staying head frames. There is given a technique of dynamic tests of the staying head frame structures. It was established that the results of the dynamic tests allow making the current control of structural system integrity. Spectrograms of forced displacements make it possible to reveal dangerous resonance phenomena in the system “a head frame-a hoist engine” Spectrograms of dynamic stresses in the elements of the main bearing structures are the information for estimating and forecasting the life time of building structures by the fatigue strength criteria.
Keywords: staying head frames, dynamic tests, technical diagnostics.
A.A.Kudlay
Mismatch of basic units as a parameter of estimating a deflected mode of power transmission lines (PTL)
Orenburg State University
Abstract. This article is devoted to an estimation of the reliability of PTL steel towers. Nowadays, a durability of the existing towers is mainly exhausted, but their replacement involves high material costs. According to the author’s observations, in most cases steel towers are in a good working condition and their service life can be prolonged. At the same time the author found out the presence of relative displacements of basic units of tetrahedral towers that cause (due to some static indeterminateness of the scheme) additional internal effects. The calculations done with the help of the program complexes have showed that in some cases under adverse weather conditions a loss of tower stability can take place despite full correspondences of towers to the project requirements. Corrections to the existing normative documents are suggested to be done.
Keywords: overhead power transmission lines, tower, a deflected mode, height difference, a heeling, mismatch of units.