RU154158U1 - THREE-FACED COVERING FARM (OVERLAPPING) FROM RECTANGULAR PIPES - Google Patents

Abstract

A three-sided truss of a covering (overlapping) of rectangular pipes, including two upper belts united by a sheeting laid on them, one lower belt connected to the upper belts by means of two inclined lattices, characterized in that all the rods of both lattices are made with the same grooves of their end edges and centered in the non-shaped nodes on the ribs between the walls (vertical faces) and the shelves (horizontal faces) of the waist pipes.

Description

The proposed technical solution relates to the field of construction and can be used as supporting structures for coatings (floors) of buildings and structures for various purposes.

A known design of driveless coatings from trihedral trusses with box sections of the two upper belts of rectangular cross section, formed from the feathers of two equal-angled corners. Braces are attached to these belts, as well as to the lower belt from a single corner using fittings [Avanesov S.I., Chikhachev T.V., Baloyan A.V., Abovyan A.G. Metal farm. - Copyright certificate No. 1544921, 02.23.1990, bull. No. 7]. The presence of fittings negatively affects the material consumption and the complexity of manufacturing, which is characteristic of all lattice structures with shaped units. In this case, labor costs additionally increase, since for skipping cuts in the upper chords, it is necessary to perform the corresponding slots.

Also known is the design of run-off coatings from trihedral faceless trusses with box sections of all quadrangular belts formed from two unequal corners joined by feathers welded with the same shelves. The truss belts fit into a regular triangle, which provides straight cuts to grill rods, also made of rectangular welded pipes [A. Kolzeev Assessment of the effect of a closed cross-sectional shape on the stability of compressed steel rods of three-belt trusses - News of universities. Construction, 2012, No. 11-12. - S.108-113]. Composite sections from rolled corners have two drawbacks: in terms of consumption of structural material, they are noticeably inferior to rectangular pipes from bent-welded closed profiles, and their double and extended welds increase the complexity of manufacturing.

The closest technical solution (adopted as a prototype) to the proposed load-bearing structure is a frameless trihedral truss farm without a permanent coating of rectangular pipes, which are closed bent-welded profiles. The pipe of the lower zone has a square section, the diagonals of which are vertically and horizontally [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. 70, fig. 6.1, 6.2]. Here, in order to avoid punching (pulling out), the width of the lattice pipe should not be less than 0.6 of the transverse dimension of the belt pipe. Taking this restriction into account reduces the stress concentration, but leads to an increase in the consumption of material on the rods and an increase in the metal consumption of the structure. In addition, the adjoining rods of inclined gratings to the lower and upper waist pipes differ from each other, which is accompanied by an increase in labor costs in their manufacture.

The technical result of the proposed solution is to increase the degree of unification of the rods of the gratings, reduce the concentration of stresses in the packaged units, increase the bearing capacity of the structure with a decrease in the consumption of its structural material.

The specified technical result is achieved by the fact that in a trihedral truss of a covering (overlap) of rectangular pipes, including two upper belts united by a sheeting laid on them, one lower belt connected to the upper belts by means of two inclined lattices, all rods of both lattices are made with the same grooves their end edges and are centered in frameless nodes on the ribs between the walls (vertical faces) and shelves (horizontal faces) of the waist pipes.

Cutting the end edges of the rods has a certain area of rational application in the non-shaped nodal joints of flat lattice structures of rectangular pipes (closed bent welded profiles), where the cross sections of the core elements of the belts and the lattice are deployed diagonally relative to the plane of the structure, that is, the diagonals of the sections are located in the plane of the lattice. Theoretical (numerical) and experimental studies of such nodes showed that their use is accompanied by an improvement in the technical and economic characteristics of load-bearing structures: stress concentration decreases, reliability, corrosion resistance and load-bearing capacity increase, and the consumption of structural material decreases [1. 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; 2. Kuznetsov Α.Φ., Kuznetsov V.A. Steel grating runs from pipes for building coatings, resistant to corrosion. - Volga Scientific Journal, 2012, No. 3. - S. 20-26; 3. Baykov D.A., Kolesov A.I., Maslov D.S. Numerical studies of the actual operation of truss units made of square pipes connected to an edge. - Volga Scientific Journal, 2012, No. 4. - S. 36-40]. The described nodes are implemented in farms of square pipes [Kuznetsov AF, Kuznetsov VA Farm of square pipes. - Patent No. 116877, 06/10/2012, bull. No. 16], as well as in structures of rectangular, rhombic and pentagonal closed bent-welded profiles [1. Marutyan A.S., Kobalia T.L., Pavlenko Yu.I., Glukhov S.A. Nodal non-block connection of tubular elements of farms. - Patent No. 116526, 05.27.2012, bull. No. 15; 2. Marutyan A.S., Ekba S.I. Design of steel trusses of coatings from rectangular, rhombic and pentagonal closed bent-welded profiles: A training manual. - Pyatigorsk: SKFU, 2012. - 156 s].

Cutting the end edges of the rods is also used in frameless units, where only cross sections of the core elements of the belts are developed diagonally relative to the plane of construction. If in the previous case, the groove is necessary for all end edges, then in this case, the groove V-shaped should have only end edges that are not parallel to the plane of the structure [1. Zinkova V.Α., Sokolov A.A. Nodular non-shaped connection of tubular elements of the farm (options). - Patent No. 2229361, 07.20.2008, bull. No. 20; 2. Zinkova V.Α., Solodov N.V. Investigation of the stress-strain state of non-shaped nodes of tubular trusses. - Modern problems of science and education, 2013, No. 6. - S.205 (Publishing House "Academy of Natural Sciences", Penza)]. Such nodal joints have been tested in farms and trellised runs of square pipes with an upper belt reinforced with a channel [1. Marutyan A.S. Square pipe truss with a top belt reinforced with a channel. - Patent No. 143426, 07.20.2014, bull. No. 20; 2. Marutyan A.S. Calculation and experimental design of steel grating runs from bent sections: Training (reference) manual. - Pyatigorsk: SKFU, 2014. - 116 s].

All the above developments are made in relation to flat structures. However, their reflection in spatial modifications, including trihedral farms, can give no less positive effect.

The proposed technical solution is illustrated by graphic materials, where in FIG. 1 shows a trihedral truss in which the braces are made with cutting end edges that are not parallel to the planes of the grids, side view; in FIG. 2 - trihedral truss in which the braces are made with cutting of all end edges, side view; in FIG. 3 shows a cross-section of a trihedral truss in which the braces are made with cutting end edges that are not parallel to the planes of the gratings; in FIG. 4 is a cross-sectional view of a trihedral truss in which the braces are made with cutting of all end edges.

The proposed technical solution for a trihedral truss includes a lower (extended) belt 1, two upper (compressed) belts 2 connecting their braces of the gratings 3, as well as corrugated board 4, combining the upper belts and making up the third facet of the farm. The cross sections of the lower belt 1 and the upper zones 2 are located with respect to the vertical and horizontal, which provides the same centering and adjoining to their ribs of the braces 3, thereby increasing the degree of unification and reducing the labor costs of manufacturing. In this case, the lower shelf of the lower belt can be used no less rationally than the upper shelves of the upper zones, on which corrugated board 4 is laid, for example, for the installation of a suspended ceiling.

To compare the proposed (new) technical solution with the well-known as the base object, a truss from bent-welded profiles of rectangular (square) section was adopted [N. Kuzin Design and calculation of steel trusses coatings for industrial buildings: a Training manual. - M.: Publishing house of the DIA, 1998. - S. 157-172]. In this case, the flat design is replaced by two options of a trihedral truss: according to the proposed solution and its prototype. The results of this replacement are shown in table 1, which shows that the material consumption of the proposed trihedral farm is less than that of its prototype.

For one more comparison of the proposed (new) technical solution with the truss (lattice run of the coating) made of bent-welded profiles of rectangular (square) section [Marutyan AS Calculation and experimental design of steel grating runs from bent sections: Training (reference) manual. - Pyatigorsk: SKFU, 2014. - S. 8-10], which in this case is calculated taking into account the minimum height from the condition of the maximum allowable deflection. As can be seen from table 2, the material consumption of the proposed trihedral farm is less than that of its prototype, and this decrease has become more noticeable.

Thus, the proposed technical solution allows to improve the technical, economic and other characteristics of trihedral trusses from rectangular pipes. With increasing loads, the positive effect can increase, which makes the use of trihedral trusses not only in coatings, but also in ceilings, for example, those where corrugated board provides fixed formwork and external reinforcement of slabs from reinforced concrete, is promising.

Claims (1)

A three-sided truss of a covering (overlapping) of rectangular pipes, including two upper belts united by a sheeting laid on them, one lower belt connected to the upper belts by means of two inclined lattices, characterized in that all the rods of both lattices are made with the same grooves of their end edges and centered in the non-shaped nodes on the ribs between the walls (vertical faces) and the shelves (horizontal faces) of the waist pipes.

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