Наукові горизонти (Mar 2019)
PHENOMENON OF THE MOMENT OF INERTIA APPLICATION OF FLAT SECTIONS IN GRATED STRUCTURES
Abstract
Design and calculation of grated structures (GS) is usually carried out on the basis of formulas of resistance of materials. This solves the main task of the design – the creation of a safe structure that can withstand permissible loads during the entire time of its operation. In this case, the criterion of the minimum weight of the structure can be taken as the optimality criterion. This is especially important for such areas of technology as aviation and automotive. GS are widely used in modern construction. Mainly for the overlap of large spans in order to reduce the consumption of materials used and to facilitate structures, for example, in large-span building structures of bridges, roof systems of industrial buildings, sports facilities. The fuselage of the aircraft, the hull of the vehicle carrying the body of the car (except for open bodies operating as a simple beam), a bus or a diesel locomotive, the wagon frame with the sprengel are lattice designs from the point of view of the mat. And even if they have no frame as such - the grid structure in this case is formed by the stamping and reinforcements supporting the plating, respectively, the corresponding techniques are used in their strength calculations. The peculiarity of the GS is that part of its cores work mainly in tension, and the other part mainly in compression. Moreover, the cores working in compression are usually chosen to have a larger cross section to prevent the loss of their stability, which leads to an increase in the weight of the whole structure. The use of the phenomenon of the moment of inertia of flat sections in the design of the GS allows to reduce the total weight due to the stability of compressed rods. This is achieved by the fact that the GS, including the upper and lower belts, is connected, for example, with a triangular lattice consisting of struts and braces alternately arranged to the left and right relative to the vertical plane of symmetry of the cross section of the structure, the struts and braces which has two mutually – perpendicular axes of symmetry, and the ends of the uprights and diagonals are rotated relative to each other by a multiple of π radians.
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