Combined cable-rod system with cross-type lattice

Abstract

FIELD: construction; large-span load-bearing structures.SUBSTANCE: combined cable-rod system with a cross-type lattice, in which the upper chord and posts are made of rigid rods operating under axial compression, and the lower chord and diagonals are made of flexible stretched rectilinear cables that perceive only axial tension. This division of functions allows for maximum use of the physical and mechanical properties of the elements. Weight reduction is achieved by eliminating excess rigidity in the stretched elements, which, unlike the prototype, do not require stability. The rods can be made from rolled steel (I-beams, pipes, angles) or composite profiles; the cables can be made from steel ropes, strands, tapes or polymer cables. Variants for the geometric design of the system are presented, the choice of which is determined by the type of load, the purpose of the structure and other factors.EFFECT: reducing the structure's own weight compared to the prototype and, as a consequence, in increasing the maximum possible spans.2 cl, 8 dwg

Description

[0001] The invention relates to the field of construction, namely to long-length supporting structures made of various materials, and can be used to cover large-span buildings and structures.

[0002] A combined truss is known, containing a rectilinear upper chord formed by a stiffening beam, and a curvilinear prestressed flexible supporting element (for example, a rope or reinforcement), connected by paired posts, wherein the upper chord and posts are additionally connected by small struts [1].

[0003] The disadvantage of this technical solution is the limited span, due to the maximum permissible length of a solid stiffening beam, which is determined by the physical and mechanical properties of the material. When splicing the beam from individual elements, its overall stiffness and load-bearing capacity are reduced at the joints.

[0004] The closest analogue is a cable-stayed rod system, which includes a beam diagonal truss with polygonal chords connected by posts, the heights of which are taken to be proportional to the ordinates of the diagram of bending moments from the calculated loads, as well as a supporting cable located along the lower chord of the truss and connected in a hinged-movable manner with all intermediate nodes and in a hinged-fixed manner with the support nodes [2].

[0005] The disadvantage of the prototype is the increased material consumption of the truss, caused by the structurally excessive cross-section of the rods, which is determined not only by strength conditions, but also by additional requirements for rigidity (limiting deflections), stability during transportation and installation, manufacturability of the joint, as well as corrosion resistance.

[0006] The objective of the invention is to increase the efficiency of a long-length supporting structure by rationally dividing functions between elements operating exclusively on axial compression or tension, which allows for a reduction in the system's own weight, maintaining its bearing capacity, and increasing the maximum possible spans.

[0007] The technical result is achieved due to the fact that a lower chord and diagonals of the cross lattice, made of flexible stretched rectilinear cables that absorb axial tension, are introduced into a combined cable-rod system with a cross-type lattice, containing an upper chord and struts formed by rigid rods operating under axial compression, which makes it possible to most fully utilize the physical and mechanical properties of the elements.

[0008] The claimed invention is illustrated by the drawings presented in Figs. 1-8, which show the following variants of the geometric design of a combined cable-rod system with a cross-type lattice:

[0009] - Fig. 1 - general view of the system with parallel belts;

[0010] - Fig. 2 - general view of the trapezoidal system;

[0011] - Fig. 3 - general view of a triangular system with tightening;

[0012] - Fig. 4 - general view of the system with a broken lower and upper belt;

[0013] - Fig. 5 - general system with polygonal upper belt;

[0014] - Fig. 6 - general view of the system with a polygonal lower belt;

[0015] - Fig. 7 - general view of the fish-like system;

[0016] - Fig. 8 - general view of the sickle-shaped system.

[0017] The following designations are used in Fig. 1-8: 1 - upper chord rod; 2 - stand-rod; 3 - diagonal cable; 4 - lower chord cable.

[0018] The operating principle of the claimed invention (see Figs. 1-8) is based on the optimal redistribution of the load from the application nodes to the supports through the separation of the functions of the system elements. The key assumption is that forces are applied only at the nodes, allowing each element to work on a pure longitudinal force, excluding bending. The rigid rods of the upper chord 1 work exclusively on axial compression, and the cables of the lower chord 4 - on axial tension, forming a force couple that perceives the main bending moment. The rod-posts 2 accept the load and transfer it to the cables of the lower chord 4. The most rational outline of the system is achieved when the heights of the rod-posts 2 are taken proportional to the ordinates of the bending moment diagram from the design load, which allows for the equalization of the forces in the chords (see Fig. 6). The choice of the system outline depends on the type of loads acting on it, the purpose of the structure, architectural requirements and other factors.The 3-stud cables of the cross lattice ensure the geometric stability and spatial rigidity of the system under design loads: in each panel, at least one 3-stud cable is guaranteed to be in a tensioned, operational state, while a compressed 3-stud cable loses stability and fails to operate under minor forces. Its presence is necessary to support reverse loading under dynamic loads. The cables are pre-tensioned to increase rigidity and reduce deflection under operational loads.

[0019] The claimed invention is industrially applicable since it can be manufactured using a wide range of modern building materials. For the system elements operating under axial compression (upper chord rods and posts), metal sections (I-beams, channels, square and round tubes, including those made of high-strength and low-alloy steels), composite rods based on carbon fiber or fiberglass, as well as glued timber elements or elements made of structural timber (LVL, CLT) can be used. For the elements operating under axial tension (lower chord cables and diagonals), closed and open steel ropes, strand and bunch systems, liners, as well as tapes and rods made of fiber-reinforced polymer (FRP), carbon fiber (CFRP), basalt fiber reinforced plastic (BFRP), high-strength polyester and aramid ropes can be used.The use of these materials ensures the implementation of the principle of separation of functions, complies with modern technologies of factory production and installation, and allows the design to be adapted to specific design requirements for span, load, and operating conditions.

[0020] The technical result consists in reducing the dead weight of the structure in comparison with the prototype by eliminating excess rigidity in the elements operating under axial tension, and, as a consequence, in increasing the maximum possible spans.

[0021] Sources of information

[0022] 1. Russian Federation Patent No. 2072414 C1, IPC E04C 3 / 04. Combined truss I V.K. Chaadaev; patent holder: Mosstalkonstruktsiya LLC, Vladimir Konstantinovich Chaadaev. - No. 94025633 / 33; declared 08.07.1994; published 27.01.1997, Bulletin No. 3.

[0023] 2. Russian Federation Patent No. 2288332 C1, IPC E04 B 7 / 14. Cable-rod system I V.I. Korobko, R.V. Aldushkin; patent holder: State Educational Institution of Higher Professional Education "Oryol State Technical University" (OryolSTU). - No. 2005119320 / 03; declared 21.06.2005; published 27.11.2006, Bulletin No. 33.

Claims

1. A combined cable-rod system with a cross-type lattice, including an upper chord and posts formed by rigid rods operating under axial compression, characterized in that the lower chord and diagonals are made of flexible stretched rectilinear cables that absorb axial tension, and the diagonals form a cross-type lattice, ensuring the geometric immutability and spatial rigidity of the system from design loads due to the fact that in each panel at least one diagonal is guaranteed to be in a stretched working state, while a compressed diagonal loses stability under minor forces and is switched off from operation, but the presence of a compressed diagonal is necessary to absorb reverse loading under dynamic loads.

2. The system according to paragraph 1, characterized in that the cables are made with pre-tensioning.

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