S.F. Pichugin, A.V. Makhinko, N.A. Makhinko
Calculation of steel elements reliability of building structures (to Ukrainian code “DBN V.1.2-2:2006 «Loads and loadings»)
Poltava National Technical University named in honor of Yuri Kondratyuk
Abstract. This paper attack reliability estimation of building structures loaded static and quasi-static stochastic loads. Practical methods of reliability analysis of steel structure elements are proposed. Analytical probabilistic models are developed for maxima of stochastic loads (wind and snow loads), taken into account a combined effects on building structures. Simple calculation formulas are given for the estimation of elements index reliability, loaded dead, snow and wind loads. Relative simplicity, wide range of application and precision of this method make it rather helpful for rapid engineering calculations. The worked out approach gives possibility to estimate to reliability of different structures under wind, snow and other loads. This technique allows specify some coefficients of design standards (for example combined factor).
Keywords: reliability of structures, stochastic loads, probabilistic models of load, probabilistic method.
O.I. Golodnov, O.N. Kozlova
The influence of stressed state on stability of compressed elements made of pipes
Open Join-Stock Company «V.Shimanovsky Ukrainian Research and Design Institute of Steel Construction»
Abstract. The residual stresses effect upon stability and ability to deform of the structures. This influence is ambiguous, so the problem of distribution of residual stresses in sections of elements may be regarded as urgent. In the first turn it concerns the elements with sections made of compressed welded double-tee profiles, tee sections of double angles and straight-seamed electrically welded pipes. It was proved experimentally a reduction of critical forces for compressed welded double-tee elements because of availability in chords the remaining compressive stresses and increase of critical forces for compressed elements made pipes after buttering under the angle 120 degrees. The necessity of making of the present researches has arisen in connection with an absence in normative reference sources the recommendations for determination of parameters of residual stressed state and its taking into consideration during calculation of compressed elements made of pipes.
Keywords: residual stresses, straight-seam electrically welded pipes, stability.
M.I. Kazakevich, V.M. Kosyak
Ways of preventing a fall of metallic bridge spans under seismic loads
Dnipropetrovs’k V. Lazaryan National University of Railway Transport
Abstract. There are given the main principles of designing seismic beam bridges and the basic diagrams of transferring longitudinal seismic stresses from span onto supports are described. Procedures of designing span structures are set forth in the article. There are given the results of designing top movements of different bridge bearing arrangements when metallic spans made by the standard designs of the years 1960-1995 rest on them. There are described the variants of using metallic spans of different designs to prevent their throwing down from supports under seismic loads. There are given the examples of using preventive structures of different types. Operating efficiency of using the known means against throwing down bridge metallic spans from the supports under seismic loads has been analyzed. There have put forward the basic requirements to choose protective structures when designing bridges with metallic spans in the areas of higher seismicity.
Keywords: bridge, metal, spans, seismic loads, ways against throwing down, prevention.
V.V. Kulyabko
To the principles of creating the technique of dynamic (certified and diagnostic) tests of the tower type objects
Prydneprovsk State Academy of Civil Engineering and Architecture
Abstract. Features of techniques and efficiency of carrying out dynamic tests of high-rise structures of the tower type are considered in the article. There is emphasized a necessity of specifying some parameters of design models to register parameters of self-induced and forced vibrations and other theoretical and experimental data within a dynamic primary and current passport system. Various levels of certified and diagnostic dynamic tests are offered. The matter of creating Projects of laboratories of dynamics of building structures for various scientific, educational, design, research and industrial organizations of civil engineering and engineering industry is disclosed. A model algorithm of carrying out dynamic tests of a high-rise steel support of the tower type is given. A special attention is paid to the lowest frequencies and forms of self-induced vibrations including torsion (in terms of rotary) forms.
Keywords: dynamics of structures, diagnostics of a technical state, dynamic tests, passport system, certification, bending and torsion forms of self-induced vibrations, forced vibrations.
V.V. Gubanov, I.V. Meginskaya
Determination of rational parameters of masts up to 30 meters high
The Donbas National Academy of Civil Engineering and Architecture
Abstract. The determination of areas of rational geometrical parameters of guyed masts with relatively small height is considered in the article for the purpose of simplification designing in development structural decisions for masts. The proposed method of calculation for guyed masts, is realized by computer to accelerates a planning process. It allows to optimize a decision by presetting a profile for bending moments in a mast, and also to take into account influence of different combinations of loadings and climatic factors on structures. On the basis of the method the series of numeral experiments is conducted. The most useful dependencies are the value of preliminary tension against the diameter of rope; the value of preliminary tension against the angle of slope of guys to the vertical line; the value of preliminary tension and operating tensions in guys against the location of supporting knots along the mast. On the basis of the proposed dependencies recommendations for development of guyed masts structural decision are formulated.
Keywords: guyed mast, guys, preliminary tension, geometrical parameters, diameter of rope, angle of slope of guys to the vertical line, location of supporting knots along the mast.
Ya.V. Nazim, T.Yu. Chernykh
Improvement operational characteristics of power supply structures at reconstruction
The Donbas National Academy of Civil Engineering and Architecture
Abstract. The article is devoted to the questions of improving operational characteristics of power supply structures under reconstruction or re-equipment. Not the least of the factors of strengthening is a structure material that determines the character of the structure operation in the large. There are considered the question of strengthening metal and reinforced concrete structures. As examples of strengthening metal structures there is taken a complex of design, investigation and repair works at the sections of the power supply systems. On the basis of analysis of the results of diagnostics and re-calculation of carrying structures there were suggested some effective methods of strengthening. Additional measures on strengthening support structures in terms of larger operating loads as compared to the design ones were suggested too. There are considered the methods of strengthening of the damaged reinforced concrete structures. Application of the suggested methods of strengthening is grounded by economic efficiency as compared to the replacement of structures.
Keywords: power supply structures, recalculation, strengthening, reconstruction.