RU211999U1 - TRIANGULAR EQUILATERAL PROFILE PIPE - Google Patents

Abstract

The proposed technical solution relates to the field of construction and can be used as beam and rod elements in the development of load-bearing structures of buildings and structures for various purposes. In a particular case, these can be rod elements of truss belts of non-purlin roofs, lattice roof girders or the same crossbars of wall frames. The technical result of the proposed solution is an optimized parameter of the calculated moment of section resistance in the force plane of the supporting structure in a triangular equilateral profile pipe in relation to beam elements, which increases the design and layout possibilities and expands the scope of its rational application. This result is achieved by the fact that in a triangular equilateral profile pipe, including one horizontal and two inclined edges, as well as a welded joint of inclined edges with flanges bent inside the tubular profile in the form of a vertical rib, these flanges are made triple and by welding a longitudinal seam form a vertical rib a width equal to the value of six pipe thicknesses, and a height equal to 0.2253 of the size of the pipe side along the center line of its calculated section.

Description

The proposed technical solution relates to the field of construction and can be used as beam and rod elements in the development of load-bearing structures of buildings and structures for various purposes. In a particular case, these can be rod elements of truss belts of non-purlin roofs, lattice roof girders or the same crossbars of wall frames.

Known technical solution in the form of pipes of steel triangular isosceles according to GOST 8649-57 [Salnikov G.P. Brief reference book of the machine builder. - Kyiv: State Publishing House of Technical Literature of the Ukrainian SSR, 1963. - P. 111]. A distinctive feature of this technical solution lies in the fact that the tubular profile has the shape of a rectangular isosceles (equal-leg) triangle, in which the inner radius of curvature of the legs exceeds the inner radius of curvature of the legs and hypotenuse by 1.33 ... 1.67 times. Its main drawback is due to unequal stability relative to the main central axes of the cross section, where the calculated parameters of the moments of inertia of this section can differ threefold. It should be added that in the plane of greatest rigidity, which, as a rule, is simultaneously the force plane of the supporting structure, the design modulus of this section also has two unequal parameters.

Another technical solution is known (taken as the first analogue) in the form of steel triangular equilateral pipes according to GOST 8650-57 [G.P. Brief reference book of the machine builder. - Kyiv: State Publishing House of Technical Literature of the Ukrainian SSR, 1963. - S. 111]. A distinctive feature of this technical solution lies in the fact that the tubular profile has the shape of an equilateral triangle with an inner radius of curvature equal to two of its thicknesses. Exactly the same cross-sectional shape has a shaped triangular pipe with an inner radius of curvature reduced to 0.9 ... 1.5 thickness when manufactured from steel with a tensile strength of not more than 450 MPa and 1.6 ... temporary resistance in excess of 450 MPa [Senichev S.G., Antipanov V.G., Kornilov V.L., Starikov A.I. Profile triangular pipe. - Patent No. 2312724, 12/20/2007, bul. No. 35]. Such a technical solution can be considered no less close to the proposed one and taken as a second analogue.

Profiles in the form of a regular triangle according to the technical solutions of both analogs are characterized by equal stability relative to the main central axes of their cross sections. However, in relation to beam elements, they can be further developed to optimize the design moments of resistance in the force plane of the supporting structure. In this case, it is advisable to take into account the experience of a similar study of a triangular equal-leg profile pipe, when, when optimizing it, double flanges of a welded joint of certain sizes are used as an internal stiffener [Marutyan A.S. Triangular equal-leg profile pipe (bent welded profile). - Patent No. 202405, 02/16/2021, bul. No. 5]. Therefore, such a technical solution can serve as a prototype, supplementing the already adopted two analogues.

The technical result of the proposed solution is an optimized parameter of the calculated moment of section resistance in the force plane of the supporting structure in a triangular equilateral profile pipe in relation to beam elements, which increases the design and layout possibilities and expands the scope of its rational application.

This result is achieved by the fact that in a triangular equilateral profile pipe, including one horizontal and two inclined edges, as well as a welded joint of inclined edges with flanges bent inside the tubular profile in the form of a vertical rib, these flanges are made triple and by welding a longitudinal seam form a vertical rib a width equal to the value of six pipe thicknesses, and a height equal to 0.2253 of the size of the pipe side along the center line of its calculated section.

The proposed shaped pipe has a fairly versatile technical solution, with the implementation of which for its manufacture it is possible to use straight-seam welded joints of sheet blanks of both normal 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 [Metal structures: Textbook for universities / Ed. Yu.I. Kudishin. - M.: Publishing Center "Academy", 2007. - S. 119, fig. 4.15]. The result of such assembly and welding operations can be the formation of a kind of stiffener inside a closed (tubular) profile, which, after appropriate calculation, according to the parameters specified in the project, can be given additional structural and layout functions. In particular, the optimized parameter of the design moment of resistance in the force plane of the supporting structure for beam elements from a triangular equilateral pipe can be provided using a vertical rib of triple flanges.

The proposed technical solution is illustrated by graphic materials, where

fig. 1 shows the design diagram of the cross section of a triangular equilateral pipe with a dotted designation of its middle (median) line;

fig. 2 is a cross-sectional diagram of a triangular equilateral pipe with a vertical stiffener made of triple flanging, providing an optimized parameter of its calculated modulus of resistance;

fig. 3 - a snapshot of a cut of different-sized triangular equilateral pipes with vertical stiffeners.

To derive the above ratios of the parameters of a triangular equilateral tubular profile and to quantify its 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 middle lines of which are sides of an equilateral triangle. In this case, it is permissible to perform computational calculations along the midline of a thin-walled section without taking into account its angular rounding and without taking into account numerical values containing the values of the thickness raised to the second and third powers (t ² , t ³ ) [Marutyan A.S. Optimization of structures from tubular (bent-welded) profiles of square (rectangular) and rhombic sections. - Structural mechanics and calculation of structures, 2016, No. 1. - S. 30-38].

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

height dimension

V=0.8660254U≈0.8660U;

where U is the overall dimension in width, equal to the side;

cross-sectional area

A=3.0tU,

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

ordinates of the center of gravity of the section

y _o \u003d y _min \u003d V / 3 \u003d (0.8660U) / 3 \u003d 0.2886666U≈0.2887U,

y _max =2V/3-2(0.866060U)=0.5773332U≈0.5773U,

where y _min - relative to the bottom face,

y _max - relative to the top corner,

_ymin + _ymax =U(0.2887+0.5773)=0.8660U=V;

moments of inertia

I _x =tU ³ (2(1 ³ /12×0.75+1(0.8660×2/3-0.4330) ² )+1(0.8660/3) ² )=

\u003d 0.2499926tU ³ ≈0.250tU ³ ,

I _Y \u003d tU ³ (2(1 ³ / 12 × 0.25 + 1 × 0.25 ² ) + 1712) \u003d 0.2499999tU ³ 0.250tU ³ ,

Ix/ _{Iy =} 1.0,

where sin ² α=0.25, cos ² α=0.75, α=30°;

moments of resistance

W _x,min tU ² 0.25/0.5773=0.4330504tU ² ≈0.4330tU ² ,

W _x,max \u003d tU ² 0.25 / 0.2887 \u003d 0.8659508tU ² 0.8660tU ² ,

W _y \u003d tU ² 0.25 / 0.50 \u003d 0.50tU ² ;

radii of gyration

i _x =i _y =U(0.25/3.0) ^1/2 =0.2886750U≈0.2887U.

As expected, the numerical values of the axial moments of inertia practically coincided, which once again confirms the quite acceptable correctness of the approximate calculation method for the thin-walled section centerline for solving the optimization problem.

The optimized parameter of the design moment of resistance is achievable only if the center of gravity of the cross section is located at the middle of its height, which can be fully ensured by including an internal rib with a size of 6txh in the design section of the tubular profile:

A=3.0tU+6th.

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:

y _o \u003d 0.5 V \u003d 0.4330U;

y _o =(3.0tU×0.5773U+6th×0.5h)/(3.0tU+6th);

0.4330U=(3.0tU×0.5773U+6th×0.5h)/(3.0tU+6th);

h ² -0.8660Uh+0.4330U ² =0;

h ₁ \u003d 0.2252605U;

h ₂ \u003d 0.6407395U.

For further development, it is advisable to take

h=0.2252605U≈=0.2253U.

Then a triangular equilateral pipe with this size of the inner rib will have the following sectional characteristics:

A=tU(3.0+6×0.2253)=4.3518tU;

y _o =0.4330U;

I _x \u003d tU ³ (0.250 + 3.0 (0.5773-0.4330) ² +

+6×0.2253 ³ /12+6×0.2253(0.4330-0.5×0.2253) ² )=

\u003d 0.4569125tU ³ ;

W _x \u003d tU ² 0.4569125 / 0.4330 \u003d 1.0552251tU ² ;

i _x \u003d U (0.4569125 / 4.3518) ^1/2 \u003d 0.3240276U;

I _y \u003d 0.250tU ³ ; W _y \u003d 0.50tU ² ; i _y =0.2887U.

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 4.3518/3.0=1.45 times, then the moment of inertia in the plane of the structure increased by 0.4569125/0.250 =1.83 times, the optimized parameter of the moment of resistance increased by 1.0552251/0.8660=1.22 times, the radius of inertia increased by 0.3240276/0.2887=1.12 times. With all this, for a triangular pipe with an internal rib (h / U = 0.2253/1), the center of gravity of the cross section is in the middle of the size in height, which increases its design and layout possibilities for use in beam elements of load-bearing structures.

Thus, the given calculation calculations confirm their correctness and rationality of the proposed triangular equilateral pipe with a vertical rib in one version and with inclined reinforcements of its side walls in another version. At the same time, the versatility of its technical solution ensures the location of the center of gravity of the section at the middle of the size in height and optimizes the parameter of the moment of section resistance in the power plane of the load-bearing structures of various buildings and structures.

Claims (1)

Triangular equilateral profile pipe, including one horizontal and two inclined edges, as well as a welded joint of inclined edges with double flanges bent inside the tubular profile in the form of a vertical rib, characterized in that the flanges are triple and by welding a longitudinal seam form a vertical rib with a width equal to the value of six pipe thicknesses, and a height of 0.2253 of the size of the side of the pipe along the center line of its calculated section.

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