Volodymyr Permyakov, Olexandr Glitin
Optimum design of portal steel frames with bearing members of a variable stiffness according to the length
Kyiv National University of Civil Engineering and Architecture
Abstract. Volodymyr,Permyakov;Olexandr,Glitin ABSTRACT: This article is devoted to the problem of optimum design of portal steel frames with bearing I- members of a variable stiffness according to the length. Design recommendations for this kind of portal steel frames were developed and presented in the article. Numerical experiments and testing of steel portal frames were executed. Numerical researches were based on the parametrical optimization model which was presented as a nonlinear programming task. Optimal geometrical and crosssectional parameters of steel portal frames were obtained using the software which realizes searching gradient methods using gradient projection method. These recommendations include a definition of discrete element numbers which are used to approximate members with a variable stiffness according to the length, to calculate an optimum value of a roof slope, to define an optimum ratio of a wall height at the beginning and at the end of the structural member as well as an optimum configuration of a horizontal bracing system in the roof and a vertical bracing system between columns.
Keywords: optimum design, steel frames;discrete elements, members with a variable stiffness according to the length.
Ivan Peleshko, Vitalina Yurchenko
Optimum design of steel structures: state of art
National University “Lvivska politechnika”Kyiv National University of Civil Engineering and Architecture
Abstract. The article presents a review of scientific researches devoted to the problem of an optimum design of steel structures. Some key features for parametric and structural-parametric optimization tasks were considered.Various formulations of structural optimization tasks such as deterministic and probabilistic mathematical models as well as multi-criteria mathematical models are presented. Thus, reliability and power capacitance criteria were taken into account and practical tasks of steel structures based on these criteria were presented.Moreover, different optimization techniques of optimum decision searching, namely gradient methods, Neldor-Mid’s method, different variations of random search methods were considered. The focus is on the genetic algorithms which are widely used in the design practice
Keywords: optimum designing, steel frame structures, parametric optimization, structural optimization.
Isaak Yevzerov, Mihail Laznyuk, Tatyana Nilova
Calculation and design of guyed masts in the program “LIRA”
The State Research Institute of Automated Systems in Construction
Abstract. The implementation of the main principles of the finite element method to design steel guyed masts with the help of the LIRA program is considered. The authors focus on the main issues of solving nonlinear problems while working with the initial data and solving methods. The article shows that the design methods of solving dynamic problems can not be used in nonlinear cases. Nowadays, the FEM program development of the problem for guyed masts can not be correctly solved in a geometrically nonlinear case. Different ways of simplifying the abovementioned problem (linearization) and other approximate methods can also lead to incorrect results. Thus, it is necessary to use other methods of solving nonlinear dynamic problems. The finite difference method of solving physically nonlinear and oneside dynamic problems is used in the LIRA program. A further development of the LIRA program is carried out by the developers just in this sphere and to solve other classes of nonlinear dynamic problems, including geometrically nonlinear ones, with the help of the forth integration method, in particular.
Keywords: guyed masts, finite element method (FEM), finite element models, dynamic problem, geometric nonlinearity.
Andrei Sventikov
Analysis of a nonlinear warping of trailing spatial rod coverings
Voronezh State University of Architecture and Civil Engineering
Abstract. TFinite-element models of flexible strings in geometrically and structurally nonlinear statements are offered. A nonlinear warping of flexible elements is described by the cubic equation. It is found out that a major factor influencing flexible cores eliminating out of a structure design scheme is a string outward thrust at “zero” displacements of basic sections. To characterize a nonlinear behaviour of flexible elements, there was derived a generalizing factor of the nonlinear behaviour. Laws of warping a trailing spatial covering with the use of cross bearing strings and double-inclined suspension brackets have been studied. Specific zones of warping a trailing spatial covering have been found.
Keywords: flexible string, core, pressure, covering.
Vadim Altapov, Aleksey Solovyov, Igor Kholopov
Engineering diagnostics of metal frames of a variable i-shaped cross,section of a sports complex framework
Samara State University of Architecture and Civil Engineering
Abstract. On the basis of a generalized practice of controlling efforts in metal structures there is shown that calculation is the most rational method of controlling in the process of designing. This method requires no additional financial costs. As emphasized, the problem of calculating building structures, including combined ones, should initially considered as the problem of their rational design. There was developed a generalized mathematical model of calculating combined structures on the base of an energy approach, a deformed state of the rigidity of a girder being taken into account. There is given an essence of calculation: on the base of a system decomposition method the system is divided into two subsystems, the main and auxiliary ones. Then, with the help of the system synthesis one can calculate its stress-strained state. There is given an algorithm of controlling a system stress-strained state, an efficiency of such a control and cases of introducing such rational structures are shown.
Keywords: variable stiffness frames, flange, metal framework, engineering inspection.
Vadim Alpatov, Igor Kholopov
Geometrical form optimization of a spatiali,rod structures
Samara State University of Architecture and Civil Engineering
Abstract. There is given an analysis of the existing design concepts of bearing frameworks in the form of spatial rod structures. The existing ways of joining rod elements in the nodes of lattice spatially rod structures are estimated. It has been found out that one of the most substantial lacks of such structures is larger materials consumption. There are considered the issues of a general formulation of the problem of an optimum design of spatial rod structures. A one-criteria task of searching an optimum geometrical form with a number of restrictions is formulated for designing building and structure coverings. A minimum material volume (mass) was taken as a criterion of quality. In the mathematical model of the task there are accepted the requirements of the elements “non-degeneracy” and topology constancy. There is suggested a successive pyramided decomposition of the task of an optimum design of spatially-rod metal structures. On the right-angular design there is given a solution of the task of optimization of a geometrical form of a spatially-rod coverage structure.
Keywords: spatial lattice designs, spatially-rod, optimization of the form, optimum designing.
Yurii Kudishin, Dmitrii Drobot
Building structure survivability
Moscow State Building University
Abstract. The article highlights a still proceeding investigation of building structure survivability. “Survivability” means a structure ability to perform its functional purpose in case of failure of any of its parts. The first part of the article is devoted to the consideration of the existing view-points on and approaches to the problem. Within the postulates selected and substantiated there is formulated a simplified (engineering) design procedure as to the survivability of metal structures. As an example of using the procedure there is considered a large-span metal covering of the Ice Palace on the Khodynskoye field (Moscow).
Keywords: survivability, reliability, progressive failure, theory of systems, risk analysis, dynamic failure of an element.
Aleksandr Tusnin
Finite element for numeric computation of structures of thin,walled open profile bars
Moscow State University of Civil Engineering
Abstract. The article is devoted to the issues of numeric computation of spatial metal structures of thin-walled open profile bars. The computation being correct, a restricted torsion should be taken into consideration. Seven degrees of freedom (linear, angular movements and deplanation) are considered for structure nodes. There is given a stiffness matrix of a thin-walled bar, the restricted torsion being regarded, and the matrix of transformation of coordinates to transfer from the local system of coordinates to a general one. The results of the investigation have been used to develop a calculation complex of framing design.
Keywords: finite element, numeric computation, thin-walled bars, restricted torsion, deplanation, sectorial stresses, stiffness matrix.
Vladimir Syntsov, Vladimir Mitrofanov, Aleksandr Syntsov
Application of metallic framework for 16 floor building In Seysmoopasnom District
National Academy of Engineering and Architecture
Abstract. The article is devoted to the question of decline of resource-demanding of multistory buildings in seysmoopasnykh districts. Influencing of material of basic bearing constructions is considered is the reinforced “concrete is steel” on the decline of efforts in the elements of framework and loadings on foundations of building and foundation. The calculation of spatial computers models of 16 is conducted floor building, dynamic descriptions and level of internal efforts are certain in the elements of framework of different calculations models. The analysis of conduct of different calculations models is conducted taking into account the seismic loading.
Keywords: seysmyka, column, otpravochnaya brand, method of eventual element, calculation model.
Sergei Kuznetsov
High,rise building testing in the wind tunnel with a atmospheric surface boundary
Donbas National Academy of Civil Engineering and Architecture
Abstract. A building or structure located in immediate proximity to another building or structure is in a bit different conditions than a detached building. The State Building Codes contain wind loads for detached buildings only. It might be right as wind loads are considered to be bearable in this case.We have investigated if this statement is correct, i.e we have compared wind loads on a detached high-rise building and wind loads on two side-by-side standing high-rise buildings. The experiments were carried out in the boundary layer wind tunnel of the work group “Aerodynamik im Bauwesen” of Ruhr-University in the town of Bochum (Germany). The atmospheric boundary layer was simulated by high-drag elements and the flow was described by the exponential law. To perform the experiments there were made two similar models of high-rise buildings. The results of the experiments are given in the form of mean and root-mean-square deviations of shape factors.
Keywords: high-rise building, wind tunnel, wind load, atmospheric boundary layer.