RU212917U1 - PENTAGONAL EQUAL-CURRENT BENT-WELDED PROFILE - Google Patents

Abstract

The proposed utility model relates to the field of construction and can be used in load-bearing structures of frames, roofs, ceilings, truss and truss trusses, structures, cross systems, etc.

The technical result of the proposed solution is an optimized parameter of the calculated section modulus in the force plane of the supporting structure in a pentagonal equal-leg bent-welded profile 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 pentagonal equal-leg welded profile, including one horizontal shelf, two vertical walls and two faces inclined at 45 degrees relative to the vertical, as well as a welded joint of inclined edges with flanges bent inside the profile, these flanges form by welding a longitudinal seam a vertical rib with a width equal to six profile thicknesses and a height equal to 0.15103 of the profile width along the midline of its design section.

Description

The proposed utility model relates to the field of construction and can be used in load-bearing structures of frames, roofs, ceilings, truss and truss trusses, structures, cross systems, etc.

The rational distribution of structural material has a technical solution of rod elements from a bent thin sheet forming a closed profile of a pentagonal section [Artemyeva I.N. Aluminum in construction. - L .: Stroyizdat, 1985. - S. 61, fig. 19, d]. The disadvantage of such rod elements is manifested in their limited bearing capacity caused by the loss of local stability of a closed bent profile due to the small thickness of the sheet. Increased thinness, in addition, requires the processing of edges for seam welding in the form of additional double bends, which increases the complexity of manufacturing both the profiles themselves and structures using them.

Another technical solution is a thin-walled supporting structure of a closed section, made of channels and corners joined together by longitudinal seams with the formation of (at least one five-sided) closed cells [Kopytov M.M., Erokhin K.A., Matveev A.V. ., Kosintsev A.S., Yashin S.G. Thin-walled load-bearing structure of closed section. - Patent No. 2174576, 10.10.2001]. The essence that forms this design is a pentahedral (pentagonal) pipe, composed of rolled profiles of an open (non-closed) section, namely a channel and an equal-shelf angle, in the form of a composite box-shaped rod element. With the advantages inherent in closed profiles, this design has certain disadvantages. Among them are paired longitudinal welds (solid or intermittent), with the help of which the channel and the angle are joined together in a five-sided profile and which increase the complexity of manufacturing. Since the walls of the pentahedral profile have different thicknesses, the structural material is distributed unevenly along the perimeter of the cross section. In addition, the thin-wall parameters of the channel and angle are optimized within the framework of the formation of rolled sections of an open section independently of each other, which worsens the uniform stability characteristic of a pentahedral (pentagonal) closed section to 15% (i _x /i _y = 1.15).

The closest technical solution (taken as a prototype) to the proposed pentagonal bent-welded profile is a pentagonal closed bent-welded profile made from a single sheet blank. It has numerical parameters of the cross section, optimized according to the criterion of uniform stability relative to the central axes x-x and y-y using a conditional square closed bent-welded profile in such a way that the ratio of the height of the vertical walls of the pentagonal profile to the width of its horizontal flange is 0.54 ... 0, 61. At the same time, the real and conditional profiles have the same thickness, perimeter and cross-sectional area, which are constant values [Marutyan A.S., Kobalia T.L., Yanukyan G.M., Glukhov S.A., Pavlenko Yu .AND. Pentagonal closed bent-welded profile. - Patent No. 104582, 05/20/2011, bul. No. 14]. The proposed profile and its prototype have in their cross sections a right angle between equal sides (legs) inclined by 45 degrees relative to the vertical. Therefore, it seems quite acceptable, for greater certainty, to mark them as equal.

The profile according to the technical solution of the prototype is characterized by equal stability relative to the main central axes of its cross section. However, in relation to beam elements, it 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 similar processing of a trapezoidal profile pipe, when, when optimizing it according to the calculated moment of resistance, flanges of a welded joint of certain sizes are used as an internal stiffener [Marutyan A.S. Trapezoidal profile pipe. - Patent No. 2680564, 02/22/2019, bul. No. 6]. Therefore, such a technical solution can serve as an analogue that complements the already adopted prototype.

The technical result of the proposed solution is an optimized parameter of the calculated section modulus in the force plane of the supporting structure in a pentagonal equal-leg bent-welded profile 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 pentagonal equal-leg welded profile, including one horizontal shelf, two vertical walls and two faces inclined at 45 degrees relative to the vertical, as well as a welded joint of inclined edges with flanges bent inside the profile, these flanges form by welding a longitudinal seam a vertical rib with a width equal to six profile thicknesses and a height equal to 0.15103 of the profile width along the midline of its design section.

The proposed bend-welded profile has a fairly universal 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-walled thickness. 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 pentagonal equal-leg bent-welded profile can be provided using a vertical rib of triple flanges.

The proposed technical solution is illustrated by graphic materials, where

fig. 1 shows a cross-section of a pentagonal equal-leg profile optimized according to the criterion of equal stability by means of a conditional square closed bent-welded profile with a section b * b;

fig. 2 - calculation scheme of the cross-section of a pentagonal equal-leg profile, where the dotted line indicates its middle (median) line;

fig. 3 - cross-section with refined parameters of a pentagonal equal-leg profile, optimized according to the criterion of uniform stability;

fig. 4 - cross-section of a pentagonal equal-leg profile with a vertical stiffener made of triple flanging, providing an optimized parameter of its calculated modulus of resistance.

To derive the above ratios of the parameters of a pentagonal equal-leg bent-welded 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 five rectangular sections, the middle lines of which are sides of an equilateral pentagon. 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].

Pentagonal bend-welded profile has the following cross-section design parameters:

A=tU(2/n+1.4142135);

y _min \u003d U (1 / n ² +0.4142135 / n-0.1035533) / (2 / n + 1.4142135);

I _x \u003d tU ³ (0.6666666 / n ⁵ +2.3570225 / n ⁴ +1.7475467 / n ³ +0.0167506 / n ² -0.1190776 / n + 0.0538623) / (2 / n + 1.4142135) ² ;

I _y \u003d tU ³ (0.5 / n-0.0488157),

where t is the thickness of the profile sheet blank; U - overall dimension of the width along the center line of the calculated section; n=U/V; V is the overall dimension of the height along the center line of the calculated section; y _min - ordinate of the center of gravity relative to the midline of the horizontal face (shelf).

To clarify the design parameters of an equally stable profile, it is necessary and sufficient that its axial moments of inertia of the section be equal, which leads to the equation of the fifth degree

0.1514937n ⁵ -0.8429344n ⁴ -2.6164136n ³ -0.2524533n ² +2.3570225n+0.6666666=0

with roots

n ₁ \u003d -1.43165; n ₂ = -1.41348; n ₃ \u003d -0.3001508; n4= _0.9315083 ; n5= _7.778 .

The fourth root is of practical importance:

n=U/V=0.9315083=1/1.0735277;

A=3.5612688tU;

U=0.2807987A/t; V=0.3014451A/t;

_ymin =0.4193948U=0.1177655A/t;

I _x \u003d 0.4879486tU ³ \u003d 0.0108033A ³ / t ² ; I _y \u003d 0.4879481tU ³ \u003d 0.01088033A ³ /t ² ;

Ix/ _Iy = _1.000001≈1 .

The optimized parameter of the design moment of resistance is achievable when the center of gravity of the cross section is located at the middle of its height, which can be achieved by including the profile of an internal rib with a size of 6t×h in the design section:

A=3.5612688tU+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 =0.5V=0.5367638U;

y _o =(3.5612688tU×0.6541329U+6th×0.5h)/(3.5612688tU+6th);

0.5367638U=(3.5612688tU×0.6541329U+6th×0.5h)/(3.5612688tU+6th);

h ² -1.0735276Uh+0.1393276U ² =0;

h ₁ \u003d 0.1510338U; h ₂ \u003d 0.9224938U.

For further development, it is advisable to take

h=0.1510338U≈0.15103U.

Then a pentagonal equal-leg welded profile with such an internal rib size will have the following sectional characteristics:

A=tU(3.5612688+6×0.15103)=4.4674716tU;

y _o \u003d 0.5367638U \u003d 0.0338074A / t;

I _x \u003d tU ³ (0.4879486 + 3.5612688 (0.6541329-0.5367638) ² + 6 × 0.15103 ³ / 12 + 6 × 0.15103 (0.5367638-0.5 × 0.15103 ) ² )=0.7315226tU ³ =0.0082043A ³ /t ² .

Comparison of a pentagonal profile with an internal rib with a pentagonal profile without such a rib shows that if the cross-sectional area of the proposed profile increased by 4.4674716/3.5612688=1.2545 times, then the moment of inertia in the plane of the structure increased by 0.7315226/0 .4879486=1.4992 times. At the same time, for a pentagonal profile with an internal rib (h / U = 0.15103/1), 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 pentagonal equal-leg profile with a vertical rib. 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 section modulus in the force plane of the load-bearing structures of various buildings and structures.

Claims (1)

Pentagonal equal-leg welded profile, including one horizontal flange, two vertical walls and two sides inclined relative to the vertical by 45 °, as well as a welded joint of inclined edges with flanges bent inside the profile, these flanges form a vertical rib with a width equal to six profile thicknesses, and a height of 0.15103 of the profile width.

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