RU221057U1 - TRIANGULAR ISOSceles PROFILE PIPE - Google Patents

Abstract

The utility model relates to the field of construction and can be used as rod and beam elements in the development of load-bearing structures of buildings and structures for various purposes. In a particular case, these may be elements of belts and gratings of trusses or lattice purlins of coverings. The technical result of the proposed solution is the optimization of the moment of resistance of the section of a triangular isosceles profile pipe in relation to rod and beam elements, which increases the design and layout capabilities and expands the scope of its rational application. This result is achieved by the fact that in a triangular isosceles profile pipe, which includes in its cross section two equal faces with an angle of 120 degrees between each other and a horizontal edge opposite this angle, as well as a welded joint of equal faces with flanges bent inside the tubular profile, these After welding the longitudinal seam, the flanges form a vertical rib with a width equal to 14 pipe thicknesses and a height equal to 0.0667 of the pipe width. 2 ill.

Description

The proposed technical solution relates to the field of construction and can be used as rod and beam elements in the development of load-bearing structures of buildings and structures for various purposes. In particular, these can be elements of belts and gratings of trusses or lattice purlins of coverings.

A technical solution is known in the form of steel triangular isosceles pipes in accordance with GOST 8649-57 [Salnikov G.P. A short reference book for a mechanical engineer. Kyiv: State Publishing House of Technical Literature of the Ukrainian SSR, 1963. P. 111]. It can be mistaken for an analogue, which is characterized by three main distinctive features. One of them is a right angle between equal sides (legs), which allows for greater certainty to mark such a profile pipe as equal-length. Another feature is different stability relative to the main central axes of the cross sections, where the calculated parameters of the moments of inertia of these sections can differ threefold. Another sign is that the internal radius of curvature of the legs exceeds the internal radius of curvature of the legs and hypotenuse by 1.33...1.67 times. The orthogonality of an equal-length (isosceles) profile pipe according to a technical solution from an analogue facilitates its use in building structures. However, in the general case, for truss, structural, cross and other lattice structures of buildings and structures, an equal-length profile pipe needs additional development as a rod element, equally stable from the plane and in the plane of the supporting structure.

The closest technical solution (adopted as a prototype) to the proposed one is a triangular equal-length profile pipe, which includes two inclined faces in the form of legs and a horizontal face in the form of the hypotenuse of an isosceles right triangle in cross section, as well as a welded joint of legs with flanges. These flanges are bent inside the tubular profile and, after welding the longitudinal seam, they form a vertical rib with a width equal to 4 pipe thicknesses and a height of 0.2698 hypotenuse [Marutyan A.S. Triangular equal-length profile pipe (bent-welded profile) // Patent No. 202405. 02/16/2021. Bull. No. 5]. The vertical rib and its design parameters provide the same stability out of the plane and in the plane of the supporting structure for rod elements made of triangular equal-length pipes. In particular, such elements can be belts of truss structures, which are effective when combined with similar belts made of pentagonal equal-length pipes. No less rational for truss structures is the assembly of chords made of triangular and pentagonal isosceles pipes with the replacement of a right angle by an angle of 120 degrees [Marutyan A.S. Optimization of truss structures with chords made of pentagonal equal-length and isosceles profile pipes // Structural mechanics and design of structures. 2022, no. 5. P. 54-62]. Therefore, of practical interest is the development of a triangular isosceles profile pipe, which includes in its cross section two equal faces with an angle of 120 degrees between them and a horizontal face opposite this angle. The welded joint of equal faces with flanges and its design parameters do not provide the same stability, but make it possible to bring the center of gravity of the section to the middle of its height and optimize the moment of resistance of the tubular profile.

The technical result of the proposed solution is the optimization of the moment of resistance of the section of a triangular isosceles profile pipe in relation to rod and beam elements, which increases the design and layout capabilities and expands the scope of its rational application.

This result is achieved by the fact that in a triangular isosceles profile pipe, which includes in its cross section two equal faces with an angle of 120 degrees between each other and a horizontal edge opposite this angle, as well as a welded joint of equal faces with flanges bent inside the tubular profile, these After welding the longitudinal seam, the flanges form a vertical rib with a width equal to 14 pipe thicknesses and a height equal to 0.0667 of the pipe width.

The proposed profile pipe has a fairly universal technical solution, with the implementation of which for its production it is possible to use straight-seam welded joints of sheet blanks of both regular and increased thin-walledness. In the latter case, according to the technological requirements for applying welds, it is necessary to cut the edges for welding in the form of flanging them [Metal structures / Ed. Yu.I. Kudishina. M.: Publishing center "Academy", 2007. P. 119]. The result of such assembly and welding operations may well be the formation of a stiffening rib inside the tubular profile, to which it is advisable, after appropriate calculations in accordance with the parameters specified in the project, to be given additional structural and layout functions. In particular, the internal rib from the calculated flanges can bring the center of gravity of the section to the middle of its height and optimize the moment of resistance of the tubular profile.

The proposed technical solution is illustrated with graphic materials, where

fig. Figure 1 shows a design diagram of the cross section of a triangular isosceles pipe with an angle of 120°, and the dotted line indicates the middle line of the thin-walled section;

fig. 2 - diagram of the cross section of a triangular isosceles pipe with an optimized moment of resistance.

To derive the given ratios of the parameters of a triangular isosceles tubular profile and quantify its load-bearing capacity, it is advisable to calculate the moments of inertia of the section I _x and I _y relative to the main central axes, as well as the section area A. Such a section can be considered a composite of three rectangular sections, the center lines of which are lateral sides with an angle of 120 degrees to each other, as well as the base of an isosceles triangle. In this case, it is permissible to perform calculation calculations along the middle line of a thin-walled section without taking into account its angular roundings and without taking into account numerical values containing the values of thickness raised to the second and third power (t ² , t ³ ) [Marutyan A.S. Optimization of structures made of tubular (bent-welded) profiles of square (rectangular) and rhombic sections // Structural mechanics and calculation of structures. 2016, no. 1. P. 30-38].

A triangular equal-length pipe has the following design cross-section parameters:

- overall height dimensions

V=0.288675U,

where U is the overall width dimension equal to the base;

- size (length) of the sides

- cross-sectional area

A=tU(1+2×0.5773502)=2.1547004tU,

where t is the thickness of the tubular profile sheet blank;

- ordinates of the center of gravity of the section

where y _min is relative to the bottom edge, y _max is relative to the top of the 120° angle,

- moments of inertia

Where

- radii of inertia

- moments of resistance

The resulting calculation formulas can be tested if the ratio of the dimensions of the width and height of the section of a triangular isosceles pipe is substituted into the calculation formulas of a pentagonal isosceles pipe:

where the parameters of the triangular profile are taken as the reference (100 percent) indicators.

As you can see, the calculation calculations have sufficiently acceptable errors for further use in solving the optimization problem.

The optimized value of the calculated moment of resistance occurs only under the condition that the center of gravity of the cross section is located at the middle of its height, which can easily be achieved by including an internal rib of size 14P in the design section of a tubular profile:

A=2.1547004tU+14th.

The linear size of the rib h must be calculated so that the ordinate of the center of gravity is equal to half the size in height:

In further study it is advisable to take

h=0.0667257U≈0.0667U.

Then a triangular isosceles pipe with this internal rib size will have the following section characteristics:

A comparison of a triangular pipe with an internal rib with a triangular pipe without such a rib shows that if the cross-sectional area of the proposed pipe increased by 3.0888602/2.1547004=1.43 times, then the moment of inertia in the plane of the structure increased by 0.0029240/0 .0019942=1.47 times, the optimized parameter of the moment of resistance increased by 0.0625761/0.0446574=1.40 times, the radius of gyration increased by 0.0540747/0.0446578=1.21 times. At the same time, for a triangular pipe with an internal rib (h/U = 0.0667/1), the center of gravity of the cross section is in the middle of the height dimension, which increases its design and layout capabilities for use in rod and beam elements of load-bearing structures.

Claims (1)

A triangular isosceles profile pipe, including in its cross section two equal faces with an angle of 120 degrees between each other and a horizontal face opposite this angle, as well as a welded joint of equal faces with flanges bent inside the tubular profile, characterized in that these flanges after welding the longitudinal seam is formed by a vertical rib with a width equal to 14 pipe thicknesses and a height equal to 0.0667 of the pipe width.

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