RU143426U1 - SQUARE PIPES FARM WITH TOP BELT STRENGTHENED WITH A CHANNEL - Google Patents

Abstract

A farm of square pipes whose edges are located at an angle of 45 ° relative to the plane of the lattice with the formation of nodes, where all the faces of the ends of the lattice elements cover two adjacent faces of each belt, characterized in that in the upper zone a square pipe is used, welded for reinforcement with a channel, moreover the channel is placed flat so that its horizontal shelf and both vertical walls cover two adjacent edges of the belt, free in junctions from the adjoining elements of the lattice.

Description

The proposed technical solution relates to the production of building lengthy load-bearing metal structures from pipes and can be used in farms, girders, columns, arches, frames and other lattice structures. The increased technical and economic characteristics of tubular building structures are due to a very rational distribution of the structural material (metal) along the perimeter of the cross-section of the elements. However, further improvement of the quality parameters due to the use of more economical especially thin-walled pipes (closed bent-welded profiles) is hindered due to the complexity of the technical solutions of the nodal connections of the rod elements in lattice structures.

The greatest distribution in tubular farms was given to nodular shaped fittings with direct adjoining of the lattice rods to the belts [1. Metal constructions. In 3 t. T. 1. Elements of construction: Textbook. for universities / Ed. V.V. Grief. - M.: Higher School, 2001 .-- S. 459, 462, Fig. 7.26, a; 7.28, a; 2. Metal structures: Textbook. for universities / Ed. Yu.I. Kudishin. - M.: Academy, 2007 .-- S. 292, 295, Fig. 9.24, 9.27]. Here, in order to avoid punching (pulling out), the diameter of the lattice pipe should not be less than 0.3 of the diameter of the belt pipe. In farms of rectangular (square) pipes, this restriction is doubled twice, that is, the width of the lattice rod should be taken at least 0.6 of the transverse size of the belt.

The disadvantage of the described nodes is the noted limitation, the consideration of which leads to an increase in the consumption of material on the rods and increase the metal consumption of the structure. At the same time, strict observance of all requirements only partially reduces the concentration of stresses in the nodes, since of the four faces (walls) of the belt elements, only one is directly coupled to the ends of the core elements of the lattice.

Another well-known technical solution is a lattice structure with a nodal non-shaped connection of tubular elements of the truss, in which the diagonal cross-section of a rectangular (square) belt is located in the axial plane of the truss, and the braces at the point of contact have a through cutout of a V-shape that completely repeats the geometry of this adjacency . Due to such a cutout, the connection of each of the lattice elements with the belt is carried out along two adjacent walls [Zinkova V.A., Sokolov A.A. Nodal non-block connection of tubular elements of the farm. - Patent No. 2229361, 07.20.2008, bull. No. 20]. Here, of the four faces (walls) of the belt elements, two of them and a rib between it are directly mated to the V-shaped ends of the lattice core elements. Numerical studies of such nodes and their comparison with traditional (typical) solutions showed that, under the same conditions, the transverse strains decreased and were distributed uniformly along the length of the belt without any special extrema [Sokolov AA, Logachev KI, Zinkova VA Numerical studies of the stress-strain state of nodular sleeveless joints of tubular elements of farms. - Industrial and civil engineering, 2007, No. 8. - S. 40-41]. A uniform (smooth) distribution of deformations indicates a decrease in stress concentration, approximately proportional to an increase in the length of the junction of the core elements of the lattice.

A newer known technical solution is characterized in that in the axial plane of the truss from square pipes there are diagonals of cross sections of all the rod elements (both the upper belt and the lower belt, and the lattice elements between them) [Kuznetsov AF, Kuznetsov VA Farm of square pipes. - Patent No. 116877, 06/10/2012, bull. No. 16]. Nodular non-shaped compounds of such a farm were successfully tested in 1991-2001 [J.A. Packer, J. Wardenier, X. - L. Zhao, G. J. van der Vegte and Y. Kurobane. Construction with hollow steel sections. Design Guide for rectangular hollow section (RHS) joints under predominantly static loading. CIDECT, 2009. - P. 100-101]. As in the previous case, modern numerical studies of these nodes and their comparison with traditional (typical) solutions have shown that, under the same conditions, a decrease in stress concentration and an increase in load bearing capacity are approximately proportional to the increase in weld lengths (the length of the junction of the lattice bar elements) [Baykov D.A., Kolesov A.I., Maslov D.S. Numerical studies of the actual operation of farm nodes from square pipes connected to nodes on an edge. - Volga Scientific Journal, 2012, No. 4. - S. 36-40].

A disadvantage common to both known technical solutions is the difficulty of their application in non-run coating farms, since the edge of the belt can crush profiled sheets of flooring. In running coatings, the very edge of the belt can be wrinkled by the run, therefore, it is necessary to arrange support tables for runs, which negatively affects the material consumption of structures, and also increases the complexity of their manufacture and installation.

The noted drawback can be eliminated by replacing square pipes of the upper waist elements with five-sided pipes of composite section, welded from channels and equal-angle corners [Kuznetsov AF, Kuznetsov VA Steel grating runs from pipes for building coatings, resistant to corrosion. - Volga Scientific Journal, 2012, No. 3. - S. 20-26]. Such a technical solution is the closest to the proposed one, that is, a prototype, the disadvantage of which is the belt elements from five-sided pipes, which negatively affect the unification and material consumption of the supporting structures. This disadvantage is due to the arrangement of five-sided pipes from rolling channels and equal-angle corners with section parameters optimized independently of each other [Kopytov MM, Matveev A.V. Lightweight metal structures from five-sided pipes. - Tomsk: STT, 2007. - 124 s].

The technical result of the proposed solution is to reduce the material consumption of the supporting structure with the expansion of its layout and unification capabilities.

The specified technical result is achieved by the fact that in a farm with a lower belt and a square pipe grid, an upper belt of a five-sided pipe welded from a channel and an equal-angle corner, the inclined edges of which, like all the edges of square pipes, are located at an angle of 45 ° relative to the plane of the grid with the formation of nodes, where all the faces of the ends of the lattice elements cover two adjacent faces of each belt, in the upper zone, instead of a five-sided pipe, a square pipe is used, welded for reinforcement with a channel, and the channel is placed n flat so that its horizontal leg and both vertical walls include two adjacent faces of the belt, the free nodes in the lattice elements of the adjacency.

The proposed truss of square pipes with a top belt reinforced with a channel has a fairly universal solution, in the implementation of which both rolled and bent, bent-welded profiles and their combinations can be used for this belt. In the particular case, there is the possibility of re-applying square profiles of the elements of the lattice or the lower zone. In this case, the cross sections of the lattice elements can be oriented relative to the axial plane of the truss (load-bearing structure) orthogonally (orthogonal braces) or diagonally (diagonal braces).

The layout of the belt element of a square pipe and channel includes four working versions:

- the channel is supported on the upper and side ribs of the pipe;

- the channel is supported on the side ribs of the pipe;

- the channel is supported on the side of the pipe and the rib between them;

- the channel is supported on the edge of the pipe.

Obviously, the first version allows you to compose a composite section, the most stringent ceteris paribus. However, other versions of the layout provide the necessary and sufficient resource of the bearing capacity of the core element. In particular, the third version of the layout is used in the well-known technical solution of symmetrical trusses from single angles, where the angular profile of the upper belt is reinforced with a channel supported on the edge of this profile and an edge between them [Shimanovsky OV, Bozhko VA, Perelmuter A. AT. New technical solutions for symmetrical trusses from single corners. - Collection of scientific papers of the Ukrainian Institute of Steel Structures. V.M. Shimanovsky (UkrNIIPSK). - Kiev: Steel Publishing House, 2008, Issue 1. - P. 80-84, Fig. 2]. If necessary, a similar reinforcement by the channel of a square pipe of the lattice element or the lower belt (all layout versions) is possible, for example, for a suspended ceiling device.

The proposed technical solution is illustrated by graphic materials, where in FIG. 1 shows a fragment of a truss from square pipes with an upper belt reinforced with a channel, supported on the upper and side ribs of the pipe, and orthogonal braces, axonometry (welds are conventionally not shown); in FIG. 2 - the same with diagonal braces; in FIG. Figure 3 shows a fragment of a truss from square pipes with an upper belt reinforced with a channel supported on the side ribs of the pipe and orthogonal braces, axonometry (welds are conventionally not shown); in FIG. Figure 4 shows a fragment of a truss from square pipes with an upper belt reinforced with a channel supported on the pipe face and an edge between them, and with diagonal braces, axonometry (welds are conventionally not shown); in FIG. 5 shows a fragment of a truss from square pipes with an upper belt reinforced with a channel supported on the side of the pipe and orthogonal braces, axonometry (welds are conventionally not shown); in FIG. 6 - the same with diagonal braces and a lower belt reinforced with a channel.

The proposed truss (lattice structure) includes an upper (compressed) belt 1 from a square pipe 2 reinforced with a channel 3, and a lower (extended) belt 4 from a square pipe. Elements of the lattice (also from square pipes), uniting the belts, can be orthogonal braces 5 or diagonal braces 6. If necessary, the square pipe of the lower belt 4 can also be supported by a channel 7.

To compare the proposed technical solution with the well-known as the base object, upper (compressed) belts of five-sided pipes from steel grating runs with a span length of 12 m and permissible design loads of 6.2 were adopted; 7.9; 11.1; 16.5; 18.2 and 31.8 kN / m [Kuznetsov A.F., Kuznetsov V.A. Steel grating runs from pipes for building coatings, resistant to corrosion. - Volga Scientific Journal, 2012, No. 3. - S. 20-26]. The calculated parameters of the cross sections of five-sided pipes are taken from their range [Kopytov MM, Matveev A.V. Lightweight metal structures from five-sided pipes. - Tomsk: STT, 2007. - S. 113-114]. The new solution is represented by upper belts of square pipes according to GOST R 54157-2010 and bent channels according to GOST 8278-83, arranged and calculated with reference to the same runs.

It can be clearly seen from the comparison in tabular form that the consumption of structural material for waist elements by the new solution has decreased, and the calculated parameters of their cross sections have increased. In this case, with a fixed load, it is possible to reduce the metal consumption of the supporting structure or, without changing the mass of the structure, increase the permissible load. An additional positive effect of the new solution is manifested in the fact that the assortment range for bent channels and bent square welds is longer than for rolled channels and equal-angle corners, and this expands the layout and unification capabilities of the proposed design. So, in the base object, the upper (compressed) belt of a five-sided pipe ⌂ [18∟125 × 8 is used twice: with an allowable design load of 16.5 and 18.2 kN / m. The rationality of replacing the waist element in relation to the larger of these two loads is shown in the table. A similar replacement is also effective for less load, when the consumption of structural material can be reduced by 31.71 / 27.88 = 1.14 times, where 27.88 kg / m is the linear density of the belt element of a composite section ◇ 140 × 4.5 [ 200 × 100 × 3.

Reuse in the upper zone of the square profiles of the elements of the lattice or lower zone is accompanied by an increase in the degree of unification of the proposed farm. Similarly, a suitable square profile of one of the elements of the lattice, with appropriate channel reinforcement, if necessary (for example, for the installation of a suspended ceiling) can be applied to the lower belt of the supporting structure.

Table. The calculated parameters of the cross-sections of waist elements from five-sided pipes (base object) and square pipes reinforced with channels (new solution), as well as their ratio Section mm Ordinates, mm Sectional area A, cm ² Linear density, kg / m (%) Moments of inertia, cm ⁴ (%) Moments of resistance, cm ³ (%) Radii of inertia, cm (%) h _p y _c I _x I _y W _{x min} W _{x max} W _y i _x i _y one 2 3 four 5 6 7 8 9 10 eleven 12 ⌂ [10∟70 × 8 98 42 21.57 16.93 100% 225.6 100% 250.4 100% 39.83 100% 53.87 100% 50.07 100% 3.23 100% 3.40 100% ◇ 90 × 3 [140 × 60 × 4 133.5 43.7 19.88 15.61 92.2% 311.88 138.2% 405.75 162.0% 34.73 87.2% 71.37 132.5% 57.96 115.8% 3.96 122.6% 4.52 132.9% ⌂ [12∟90 × 6 120 46 23.91 18.77 100% 370.5 100% 434 100% 50.97 100% 80.6 100% 72.33 100% 3.94 100% 4.26 100% ◇ 120 × 3 [160 × 80 × 2.5 172.5 63.8 21.53 16.90 90.0% 578.93 156.3% 628.05 144.7% 53.26 104.5% 90.74 112.6% 73.98 102.2% 5.19 131.7% 5.40 126.8% ⌂ [14∟100 × 6.5 130 51 28.42 22.31 100% 548.2 100% 684.5 100% 68.33 100% 106.49 100% 97.78 100% 4.39 100% 4.91 100% ◇ 120 × 3.5 [160 × 80 × 4 174 60 28.19 22.13 99.2% 696.94 127.1% 847.33 123.8% 61.14 89.5% 116.16 109.1% 99.69 102.0% 4.97 113.2% 5.48 111.6% ⌂ [18∟125 × 8 160 65 40.39 31.71 100% 1128.1 100% 1556.8 100% 118.22 100% 173.64 100% 172.97 100% 5.28 100% 6.21 100% ◇ 140 × 4 [200 × 100 × 5 203 68,2 40.33 31.59 99.6% 1423.81 126.2% 1826.03 117.3% 105.62 89.3% 208.77 120.2% 182.60 105.6% 5.95 112.7% 6.74 108.5% ⌂ [22∟160 × 8 200 86 58.13 45.63 100% 2704.3 100% 3339.1 100% 234.92 100% 314.36 100% 303.55 100% 6.82 100% 7.58 100% ◇ 180 × 4 [250 × 125 × 6 260 83.3 56.15 44.08 96.6% 3228.30 119.4% 4192.20 125.5% 182.70 77.8% 387.55 123.3% 330.09 108.7% 7.58 111.1% 8.64 114.0%

Claims (1)

A farm of square pipes whose edges are located at an angle of 45 ° relative to the plane of the lattice with the formation of nodes, where all the faces of the ends of the lattice elements cover two adjacent faces of each belt, characterized in that in the upper zone a square pipe is used, welded for reinforcement with a channel, moreover the channel is placed flat so that its horizontal shelf and both vertical walls cover two adjacent edges of the belt, free in junctions from the adjoining elements of the lattice.