A broken-string cross arm for a transmission line tower

Abstract

The present invention discloses a folded chord cross arm for a transmission line tower, which includes trusses, first reinforcing ribs, and second reinforcing ribs. There are two trusses, and the trusses are of a mesh structure. The outer contour thereof is in a shape of diverging in a broken line from a point towards both sides. The two trusses are arranged oppositely, and their concentrated ends are connected to each other, and there is a spacing between the diverging ends. The first reinforcing ribs and the second reinforcing ribs are respectively arranged between the opposite sides of the two trusses. The advantages of the present invention are as follows: for the steel structure cross arm mainly bearing the tension loads of conductors and ground wires, compared with the traditional cross arm, the internal force distribution of the main materials of this cross arm is more uniform and reasonable. At the same time, it can also reduce the stress level of the cross arm components. The special structural design reduces the requirements for stability in the middle of the cross arm, can make full use of the material performance, improve the structural reliability, reduce the steel consumption, and lower the project cost.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment, and particularly to a broken chord cross arm for a transmission line tower. Background Art

[0002] The cross arm of a transmission line tower bears three-way loads of conductor and ground wire tension, gravity and wind load. Among them, the tension load plays a dominant role. Taking the design conditions of the 1E6 tower in the general design of transmission line poles and towers of the State Grid as an example, in the case of a broken wire condition, the tension load is about 8.2 times the gravity load and about 6.1 times the wind load. Therefore, how to make the cross arm structure more reasonably bear the tension load is particularly crucial.

[0003] At present, there are various forms of tower cross arms, all of which are steel structures. In force analysis, they can be simplified into trusses. The common types are pointed cross arms, duckbill cross arms and rectangular cross-section cross arms. The pointed cross arm can be regarded as composed of two upper and lower trusses, which intersect at the hanging point corner, and the load acts at the corner point; the two upper and lower trusses of the duckbill cross arm intersect at a line at the hanging point. Due to the eccentricity of the hanging point, under the action of the broken wire tension, the cross arm will generate torque, and the torque is borne by the front and rear trusses; the rectangular cross-section cross arm can be regarded as composed of four upper, lower, front and rear trusses. Under the action of the broken wire tension and vertical load, the force on the upper and lower planes is similar to that of the pointed cross arm, and under the action of torque, the force is similar to that of the duckbill cross arm.

[0004] The main materials of the above several cross arms are often made of the same type of angle steel or other lattice sections, that is, one main material has the same cross-section from the hanging point to the connection between the cross arm and the tower body, and the axis of the material is a straight line throughout. In the actual force-bearing process of this structural form, the closer to the tower body, the greater the axial force of the main material, and the cross-section of the material does not change, which results in waste of materials. Summary of the Invention

[0005] Object of the Invention: Aiming at the above problems, the object of the present invention is to provide a broken chord cross arm for a transmission line tower, which improves the structural reliability, reduces the steel consumption and lowers the project cost.

[0006] Technical Solution: A broken chord cross arm for a transmission line tower includes trusses, first stiffeners and second stiffeners. There are two trusses, and the trusses are in a mesh structure. Its outer contour diverges in a broken line shape from a point to both sides. The two trusses are arranged oppositely, and their concentrated ends are connected to each other, and there is a distance between the divergent ends. The first stiffeners and the second stiffeners are respectively arranged between the opposite sides of the two trusses.

[0007] Furthermore, the truss includes end plates, truss side chords, and truss web members. There are two truss side chords, one end of each of which is connected by the end plate, and the included angle between them is an acute angle. There is at least one truss web member, which is arranged between the two truss side chords and is respectively fixed to the inner sides of the two. The truss side chords on the opposite sides of the two trusses are correspondingly connected by the first reinforcing rib and the second reinforcing rib.

[0008] Furthermore, the truss side chord includes a chord rod and a connecting plate. A plurality of chord rods are arranged in sequence, and adjacent two chord rods are connected by one connecting plate. The end plate is connected to the ends of the two corresponding chord rods on the two truss side chords. The first reinforcing rib and the second reinforcing rib are respectively connected to the corresponding connecting plates.

[0009] Preferably, the truss side chord has a broken line structure with at least two inflection points.

[0010] Furthermore, the truss web member includes web members and a web plate. There are a plurality of web members, and the plurality of web members are arranged at intervals along the circumference of the web plate. One end of each web member is respectively fixed to the outer ring of the web plate, and the other end is respectively fixed to the corresponding connecting plate.

[0011] Furthermore, there are at least two first reinforcing ribs respectively between the opposite sides of the two trusses. The first reinforcing ribs are arranged straight and fixed between the two trusses.

[0012] Furthermore, there are at least two second reinforcing ribs respectively between the opposite sides of the two trusses. The second reinforcing ribs are arranged obliquely and fixed between the two trusses.

[0013] Preferably, the included angle between the connection ends of the two trusses is an acute angle.

[0014] Preferably, the number of the first reinforcing ribs is equal to that of the second reinforcing ribs.

[0015] Advantageous effects: Compared with the prior art, the advantages of the present invention are as follows: For the steel structure cross arm mainly bearing the tension load of conductors and ground wires, this cross arm can make the internal force distribution of the main materials of the cross arm more uniform and reasonable compared with the traditional cross arm. At the same time, it can also reduce the stress level of the cross arm components. The special structural design reduces the requirements for stability in the middle of the cross arm, can make full use of the material performance, improve the structural reliability, reduce the steel consumption, and reduce the project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the bulk structure of the first embodiment of the present invention;

[0017] Figure 2The force analysis comparison diagram between the truss of Embodiment 1 of the present invention and the existing truss;

[0018] Figure 3 The schematic diagram of the bulk structure of Embodiment 2 of the present invention;

[0019] Figure 4 The schematic diagram of the structure of the present invention installed on the iron tower. Specific embodiments

[0020] The present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0021] Embodiment 1:

[0022] A broken chord cross arm for a transmission line iron tower, as Figure 1 shown, includes a truss 1, a first stiffening rib 2, and a second stiffening rib 3. There are two trusses 1. The truss 1 includes an end plate 11, a truss side chord 12, and a truss web member 13. There are two truss side chords 12. One end of the two is connected through the end plate 11, and the included angle between them is an acute angle. The truss side chord 12 includes a chord member 121 and a connecting plate 122. A plurality of chord members 121 are arranged in sequence, and adjacent two chord members 121 are connected by a connecting plate 122, so that the truss side chord 12 forms a broken line structure with at least two inflection points. There is one truss web member 13, which is arranged between the two truss side chords 12. The truss web member 13 includes a web member 131 and a web plate 132. There are a plurality of web members 131, and the plurality of web members 131 are arranged at intervals along the circumference of the web plate 132. One end of each web member 131 is fixed to the outer ring of the web plate 132 respectively, and the other end is fixed to a connecting plate 122 close to the corresponding side respectively, so that the outer contour of the truss 1 is a net-like structure that diverges from a point to both sides.

[0023] The two trusses 1 are arranged oppositely, and the end plates 11 on the concentrated ends of the two are connected to each other, and there is a distance between the divergent ends, so that the included angle between the connection ends of the two trusses 1 is an acute angle. A first stiffening rib 2 and a second stiffening rib 3 are respectively arranged between the opposite sides of the two trusses 1.

[0024] There are at least two first stiffening ribs 2 respectively between the opposite sides of the two trusses 1, and the number of the first stiffening ribs 2 on both sides is equal. The first stiffening ribs 2 are arranged straight between the two trusses 1. The two ends of the first stiffening ribs 2 are fixed to the connecting plates 122 with the same arrangement number on the two trusses 1. As the distance between the two trusses 1 expands along the extending direction of the truss side chord 12, the length of the first stiffening ribs 2 increases, that is, the first stiffening ribs 2 are adaptively provided with a variety of length specifications.

[0025] There are at least two stiffeners II 3 respectively between the opposite sides of the two trusses 1, and the number of stiffeners II 3 on both sides is equal. The stiffeners II 3 are inclined between the two trusses 1, and the inclination direction of each stiffener II 3 is the same. If one end of the stiffener II 3 is fixed to the connecting plate 122 numbered N on one of the trusses 1, the other end is fixed to the connecting plate 122 numbered N - 1 or N + 1 on the other truss 1. As the distance between the two trusses 1 increases along the extending direction of the side chord 12 of the truss, the length of the stiffener II 3 increases, that is, the stiffener II 3 is adaptively set with multiple length specifications.

[0026] The number of stiffeners I 2 is equal to that of stiffeners II 3.

[0027] In order to further enhance the stability and firmness, a reinforcing rod 14 can be added between the two connecting plates 122 ranked first starting from one side of the end plate 11 of the truss 1.

[0028] As Figure 2 shown, through the force analysis and comparison of the truss of the first embodiment of the present invention with the existing truss, relevant numerical values are calculated and analyzed with the same acting force. Since the upper and lower two trusses mainly bear the load under the broken wire condition, and the upper and lower two trusses have structural similarities, the truss of this cross arm is compared with the truss of the cross arm with a rectangular cross section under the action of unit load, and the internal force distribution under the broken wire condition is simulated (assuming that the EA of each link rod is the same). The lengths of the two cross arms are equal, and the distance between the fixed hinge supports is equal.

[0029] It can be seen from the calculation results that the internal force distribution of the main members of this cross arm is more uniform, and the internal force amplitude is smaller than that of the cross arm with a rectangular cross section. The length of the web member is shorter, and it is easier to meet the stability requirements.

[0030] As Figure 4 shown, when this cross arm is installed on the iron tower, the divergent ends of the two trusses 1 are respectively fixed to the iron tower.

[0031] Embodiment 2:

[0032] A broken chord cross arm of a transmission line iron tower. This embodiment is basically the same as Embodiment 1, and the difference lies in that: as Figure 3 shown, there are two truss web members 13, which are arranged at intervals in sequence between the two truss side chords 12 and are respectively fixed to the two truss side chords 12.

[0033] In addition to the above Embodiment 1 and Embodiment 2, the truss of the present invention can also be provided with multiple truss web members, and at the same time, the length of the truss side chord can be adaptively increased.

[0034] In actual stress, for the crossarm, the broken wire condition is generally the control condition in the direction of the transmission line. The broken wire mainly bears the load by the upper and lower trusses. Since the side chords of the crossarm truss are arranged in a broken line, the internal force distribution is more uniform and the internal force amplitude is lower than that of the straight-line arrangement, and the stress is reasonable.

[0035] The internal web members are arranged in an "island" pattern to form the truss web members. Existing crossarms often connect the upper and lower chords with full-length members, while the web members of this crossarm adopt the "island" arrangement form. The average length of the web members is smaller than that of the web member components of other crossarm forms, and it is easier to meet the structural stability requirements under the same load.

[0036] For the steel structure crossarm that mainly bears the tension load of the conductors and ground wires, this crossarm can make the internal force distribution of the main crossarm materials more uniform and reasonable compared with the traditional crossarm. At the same time, it can also reduce the stress level of the crossarm components. The special structural design reduces the requirements for stability in the middle of the crossarm, can make full use of the material properties, improve the structural reliability, reduce the steel consumption, and reduce the project cost.

Claims

1. A transmission line tower with a folded chord cross arm, characterized in that: It includes trusses (1), first stiffeners (2), and second stiffeners (3). There are two of the trusses (1), and the trusses (1) are of a mesh structure, with its outer contour diverging in a zigzag shape from a central point to both sides. The two trusses (1) are arranged oppositely, and their central ends are connected to each other, and there is a spacing between the diverging ends. The first stiffeners (2) and the second stiffeners (3) are respectively provided between the opposite sides of the two trusses (1); The truss (1) includes end plates (11), truss side chords (12), and truss web members (13). There are two of the truss side chords (12), and one end of each of them is connected by the end plate (11), and the included angle between them is an acute angle. There is at least one truss web member (13), which is arranged between the two truss side chords (12) and is respectively fixed to the inner sides of both of them. The truss side chords (12) on the opposite sides of the two trusses (1) are correspondingly connected by the first stiffeners (2) and the second stiffeners (3); The truss side chord (12) includes chord bars (121) and connecting plates (122). There are multiple chord bars (121) arranged in sequence, and adjacent two chord bars (121) are connected by one connecting plate (122). The end plate (11) is connected to the ends of the two corresponding chord bars (121) on the two truss side chords (12). The first stiffeners (2) and the second stiffeners (3) are respectively connected to the corresponding connecting plates (122); The truss web member (13) includes web bars (131) and webs (132). There are multiple web bars (131), and the multiple web bars (131) are arranged at intervals along the circumference of the web (132). One end of each web bar (131) is respectively fixed to the outer circle of the web (132), and the other end is respectively fixed to a corresponding connecting plate (122).

2. The chord-bending cross arm of a transmission line tower according to claim 1, characterized in that: The truss side chord (12) is in a broken line structure with at least two inflection points.

3. A broken chord cross arm for a transmission line tower according to claim 1, characterized in that: There are at least two first stiffeners (2) respectively between the opposite sides of the two trusses (1). The first stiffeners (2) are arranged straight and fixed between the two trusses (1).

4. A broken chord cross arm for a transmission line tower according to claim 1, characterized in that: There are at least two second stiffeners (3) respectively between the opposite sides of the two trusses (1). The second stiffeners (3) are arranged obliquely and fixed between the two trusses (1).

5. A chord-broken cross arm for a transmission line tower according to claim 1, characterized in that: The included angle between the connection ends of the two trusses (1) is an acute angle.

6. The folded chord cross arm of a transmission line tower according to claim 1, characterized in that: The number of the first stiffeners (2) is equal to that of the second stiffeners (3).

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