V. O. Popov
Modeling of a deflected mode of tower structure bearing flanges for an intelligent design
Vinnitsa National Technical University
Abstract. There is considered an analytical and numerical modeling of a deflected mode of metallic tower structure bearing flanges with the use of the up-to-date program complexes “Lira 9.4” and “Cosmos-Works” to rationalize their design. A real tower as high as 60 m being taken as an example, numerical results obtained with the help of “Lira 9.4” and “Cosmos-Works” were compared. The numerical methods realized in the program complex “Cosmos-Works” prove that a joint work at modeling structural subunits as well as redistribution of stresses which occur in welded joints make it possible to reliably estimate real stresses in a flange which turned to be much lower than those estimated analytically, and, as a result, to considerably lower its thickness.
Keywords: tower telecommunications structures, flange joint, deflected mode, reduced stresses, intelligent design.
S. F. Pichugin, A. V. Makhin’ko
Setting of wind loads on lattice towers in the standards of different countries of the world
Poltava Yu.Kondratyuck National Technical University
Abstract. The article is devoted to a consideration of setting wind loads on lattice towers in different standards of the world: the former USSR SNiP (performance requirements) 2.01.07-85, the Ukrainian DBN (performance requirements) В.1.2-2:2006, the European Norms EN 1993-3-1:2006, EN 1991-1-4:2004, the American ASCE 7-05, the British Norms BS 8100-4-1995 and the Canadian Standard CSA S37-94. There are compared normative periods of repeatability of wind velocity, vertical profiles of average velocity pressure, and aerodynamical coefficients of tower spatial sections at the most unfavourable angle of attack of a wind flow. It is shown, therewith, that developers having the norms of a various quantity of an experimental material, of the usage of different criteria for determining design value of quantities, miscalculation of their statistical performance, for using different design factor provisions, for regulation of normative techniques of different hierarchy and accuracy, the variation of their numerical estimate can reach 50%.
Keywords: codes of design, wind load, angle of attack, lattice towers, vertical profile of wind, period of repeatability, coefficient of integrity, aerodynamical coefficient.
V. V. Gubanov, I. V. Mezhinskaya
Comparison of design procedures for cellular telecommunication tower bodies
Donbas National Academy of Civil Engineering and Architecture
Abstract. There are considered the problems of cellular telecommunication tower stability. The existing design methods for tower stability have been analyzed. The design of tower stability by the exact and approximate methods was realized with the help of a computer. There were carried out some numerical experiments on the base of three cellular telecommunication towers: with two, three and four levels of guys as high as 18, 28, and 38 m, respectively. There are given the research results. The results of the exact and approximate design methods are compared by the factors of stability margin of the structures which were determined by two methods for three towers. Stability coefficients of separate pillars for these towers were designed by the standard procedure of designing axially-loaded pillars, by Euler and Yasinsky’s formulae. The results obtained by the exact and approximate design methods are compared both between themselves and with the standard procedure of designing axially-loaded pillars, by Euler and Yasinsky’s formulae. The obtained data being analyzed, there are given recommendations of designing stability for mobile communication towers. An influence of structure rigidity on tower stability is investigated with the help of the approximate design method.
Keywords: cellular telecommunication tower, tower body, stability, stability design, structure rigidity.
Ye. V. Gorokhov, V. N. Kushchenko, V. N. Vasylev, V. M. Levin, N. M. Zaichenko,
V. M. Klykov, V. N. Gubar’, Yu. Yu. Kalmykov, Yu. I. Salivon
Reconstruction of the structures of a skip hoisting plant of the main opening of the coal mining public enterprise “Krasnolimanskaya”
Donbas National Academy of Civil Engineering and Architecture
Abstract. There is considered a solution of a multi-factor design task: reconstruction of structures of a mine hoisting plant because of the replacement of a hoist engine. The basic factors making for the choice of the engineering solution were operating conditions of the structures (a shaft headgear, the hoist engine building and foundation); a simultaneous replacement of the hoist drum, the engine rotor and stator; a necessity of performing reconstruction with minimum stops of the mainline production. Accounting of the operating conditions of the hoisting plant structures was made on the base of both the survey data and full-scale tests of the building structures and an after-normalization of their technical state. To substantiate a possibility of using the shaft headgear structures for reconstruction purposes, there were fulfilled dynamic tests, the structure design scheme was checked and a revised design of extremal emergency loads was performed. The design of reconstructing the hoist engine building includes an arrangement of the transforming field-assembled aperture for replacement of a hoist drum; a change of a constructive decision as to the building covering, a change of the configuration of the hoist engine foundation. In reconstructing, an instrument inspection of including the reconstruction elements into the work, as well as a control of the technical state of the building structures.
Keywords: shaft hoist engine, shaft headgear, hoist engine building, hoist engine foundation, technical state, reconstruction.
S. I. Skrebtsov
Calculation of stability of the i-section compressed components after residual stress adjustment on a part of length
Lugansk National Agrarian University
Abstract. Residual stresses influence a structure stability and deformability. This influence is ambiguous, so, distribuation of residual sresses in the component sections is a problem of today. First of all it concerns the I-section components and a T-section of twin angles. A necessity of carrying out these investigations was due to the absence of recommendations on determining a residual stressed state in the normative documents and its accounting in designing compressed components. There has been developed a procedure of calculating the influence residual stresses on stability at their adjustment on a part of a component length by beading at the edges of belts in the middle part of a column length. There was fulfilled the first period of the computer-aided development of the calculation program which allows determining optimal parameters of the adjustment of residual stresses in I-section columns and estimating efficience quantitatively.
Keywords: residual stresses, column, stability, middle length.