CN113463966A

CN113463966A - Lattice tower type wire outlet structure

Info

Publication number: CN113463966A
Application number: CN202110764183.4A
Authority: CN
Inventors: 王宁壁; 张咪; 应捷; 顾群; 王甲麟; 张玉明; 贾鹏; 李毅; 雷蕾; 王炳媛
Original assignee: Northwest Electric Power Design Institute of China Power Engineering Consulting Group
Current assignee: Northwest Electric Power Design Institute of China Power Engineering Consulting Group
Priority date: 2021-07-06
Filing date: 2021-07-06
Publication date: 2021-10-01

Abstract

The invention discloses a lattice tower type wire outlet structure which comprises a lattice tower, a top cantilever beam, an upper cantilever beam, a middle cantilever beam and a lower cantilever beam, wherein the top cantilever beam, the upper cantilever beam, the middle cantilever beam and the lower cantilever beam are arranged along the lattice tower in the horizontal direction by one circle; the lattice tower of being qualified for next round of competitions perpendicularly saves the land use, saves the steel quantity, reduces basis and cushion cap construction cost, and the lattice tower of being qualified for next round of competitions perpendicularly installs the maintenance relatively independent, has avoided the risk of mutual restriction and error accumulation between the beam column when the door type framework is assembled, overhauls, reforms and can not reach other being qualified for the next round of competitions. Meanwhile, the conventional structural form of a portal-shaped framework with end support herringbone columns is adopted when the traditional horizontal outgoing line of the transformer substation is overturned, and the method has good reference significance for optimizing the outgoing line structural design.

Description

Lattice tower type wire outlet structure

Technical Field

The invention belongs to the field of transformer substation framework design, and particularly relates to a lattice tower type outlet structure aiming at a 330kV GIS vertical outlet arrangement scheme in compact arrangement in a transformer substation.

Background

In some areas, the 330kV outdoor GIS adopts A, B, C three-phase horizontal arrangement, the framework adopts a herringbone column door type framework structure with end supports, and the size of the transformer substation perpendicular to the wire outlet direction is not reduced by adopting compact arrangement of GIS equipment due to the limitation of the width of the wire outlet door type framework. Therefore, a vertical outgoing line mode needs to be designed, the outgoing line interval width is further reduced, and the advantage of compact GIS arrangement is fully exerted.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a lattice tower type wire outlet structure which adopts a vertical wire outlet mode, further reduces the wire outlet interval width, gives full play to the advantage of compact GIS (gas insulated switchgear) arrangement and further reduces the occupied area of a transformer substation.

In order to achieve the purpose, the invention adopts the technical scheme that: the utility model provides a tower outlet structure of lattice, includes lattice tower, top cantilever beam, upper portion cantilever beam, middle part cantilever beam and lower part cantilever beam, and top cantilever beam, upper portion cantilever beam, middle part cantilever beam and lower part cantilever beam are arranged along a week of lattice tower on the horizontal direction, and top cantilever beam, upper portion cantilever beam, middle part cantilever beam and lower part cantilever beam are from last down arranging, make A looks, B looks, C looks three-phase wire and ground wire arrange perpendicularly on the space, and two outgoing lines share one basic tower of going out.

The top cantilever beam and the middle cantilever beam are arranged in a straight line shape, and the length of the top cantilever beam is greater than that of the middle cantilever beam; the upper cantilever beam and the lower cantilever beam are arranged in a V shape, and the opening directions of the upper cantilever beam and the lower cantilever beam are deviated from each other.

The top cantilever beam, the upper cantilever beam, the middle cantilever beam and the lower cantilever beam are sequentially used as a ground wire, an A-phase cross arm, a B-phase cross arm and a C-phase cross arm from top to bottom.

The upper chords of the A-phase cross arm and the C-phase cross arm are in a straight line shape from the tower body of the lattice tower to the end part of the cross arm, and the cross section of the cross arm is in a dissimilar right trapezoid shape; the cross sections of the phase B and the ground wire cross arm are similar rectangles.

The vertical surfaces of the cantilever beams used for the phase A and the phase C are both triangular; the top cross web members are not in the same plane, and the top web members are not connected to each other.

The top cantilever beam, the upper cantilever beam, the middle cantilever beam and the lower cantilever beam are all in a lattice type.

The tower column of the lattice tower adopts a variable cross-section steel pipe lattice rectangular column.

The web members of the tower columns of the lattice tower adopt cross rods and cross rods which are symmetrically arranged, the web members with the width surface below the tower column elevation of 10.5m adopt cross rods, and transverse partitions are arranged in the horizontal planes of the cross rods; the web members of the narrow surface of the tower column and the web members of the wide surface with the elevation of more than 10.5m adopt cross rods.

Hoop plates and vertical gusset plates are arranged at the nodes of the tower columns of the lattice tower, the cross arm chord members and the horizontal web members are connected with the tower columns through the hoop plates, and the cross arm inclined chord members are connected with the tower columns through the vertical gusset plates.

The steel pipe main rod of the tower column of the lattice tower is lengthened by adopting a flange, the lower section column flange adopts a rigid flange, the upper section column flange adopts a flexible flange, and the tower column web member steel pipe is connected with the main rod steel pipe inserting plate in a single shear manner.

Compared with the prior art, the invention has at least the following beneficial effects:

the lattice tower of being qualified for next round of competitions perpendicularly saves the land use, saves the steel quantity, reduces basis and cushion cap construction cost, and the lattice tower of being qualified for next round of competitions perpendicularly installs the maintenance relatively independent, has avoided the risk of mutual restriction and error accumulation between the beam column when the door type framework is assembled, overhauls, reforms and can not reach other being qualified for the next round of competitions. Meanwhile, the conventional structural form of a door-shaped framework with end-supporting herringbone columns is adopted when the traditional horizontal outgoing line of the transformer substation is overturned, the tower structure which is another structural form of the outgoing line framework design is provided, and the optimized outgoing line structural design has good reference significance for other voltage-level vertical outgoing line arrangement schemes in compact arrangement.

Furthermore, the structural design of the line tower for hanging lines in different directions in space, particularly the design of the connecting nodes of the cross arm and the tower body, has good reference significance.

Drawings

FIG. 1 is a schematic perspective view of a vertical outlet lattice tower in which the present invention may be implemented.

Fig. 2a is a schematic elevation view of a vertical outgoing lattice tower of the present invention, fig. 2b is a schematic view of a top cantilever beam shown in fig. 2a, fig. 2c is a schematic view of an upper cantilever beam shown in fig. 2a, fig. 2d is a schematic view of a middle cantilever beam shown in fig. 2a, fig. 2e is a schematic view of a lower cantilever beam shown in fig. 2a, fig. 2f is a schematic view of a cross section of a lower portion 3-3 of the lattice tower, fig. 2g is a schematic view of a cross section of a lower portion 2-2 of the lattice tower, and fig. 2h is a schematic view of a cross section of a lower portion 1-1 of the lattice tower.

FIG. 3 is a schematic diagram of a modeling calculation model of a vertical outlet lattice tower according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a structure in which the cross arms of the phase a and the phase C are strung by straight rods.

Fig. 5 is a schematic diagram of a folding rod structure for winding on the cross arms of the phase a and the phase C.

FIG. 6 is a schematic view of the vertical surface of a lattice tower with straight rods on the cross arms of the A phase and the C phase.

Fig. 7 is a schematic vertical surface view of a lattice tower with folding rods on the cross arms of the A phase and the C phase.

FIG. 8a is a schematic view of the pipe intersecting line welding; FIG. 8b is a schematic diagram of a double-shear connection of a U-shaped insert plate; fig. 8c is a schematic view of direction A-A of fig. 8B, fig. 8d is a schematic view of single-shear connection of the board, and fig. 8e is a schematic view of direction B-B of fig. 8 d.

Fig. 9a is a schematic diagram of an implementable node connection structure.

Fig. 9b is a schematic diagram of another node connection structure that can be implemented.

FIG. 9C is a schematic view of FIG. 9a taken along line C-C.

FIG. 9D is a schematic view of FIG. 9b taken along line D-D.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

The power distribution device with 220kV and below voltage levels adopts a double-circuit single-rod vertical outgoing tower, the lead tension and outgoing height of a 330kV GIS vertical outgoing line arrangement are much larger than those of the 220kV outgoing tower, a lattice tower structure with larger resisting moment is adopted, the difference of the lattice tower structure with a circuit tower is that A-phase and C-phase cross arms, B-phase and ground wire cross arms are not in the same vertical plane, four layers of cantilever cross arms of a top cantilever beam, an upper cantilever beam, a middle cantilever beam and a lower cantilever beam are staggered front and back, the arrangement is similar to a 'meter' shape when the lattice tower is overlooked, the structural types of the A-phase and C-phase cross arms are different from the circuit tower, and the design of the cross arms is initiated and specifically as follows:

the utility model provides a tower outlet structure of lattice, includes lattice tower 1, top cantilever beam 2, upper portion cantilever beam 3, middle part cantilever beam 4 and lower part cantilever beam 5, and top cantilever beam 2, upper portion cantilever beam 3, middle part cantilever beam 4 and lower part cantilever beam 5 are arranged along a week of lattice tower 1 on the horizontal direction, and top cantilever beam 2, upper portion cantilever beam 3, middle part cantilever beam 4 and lower part cantilever beam 5 are from last down arranging, make A looks, B looks, C looks three-phase wire and ground wire arrange perpendicularly in the space, and two outgoing lines share one basic tower of going out.

The top cantilever beam 2 and the middle cantilever beam 4 are arranged in a straight line shape, and the length of the top cantilever beam 2 is greater than that of the middle cantilever beam 4; the upper cantilever beam 3 and the lower cantilever beam 5 are both arranged in a V shape, and the opening directions of the upper cantilever beam 3 and the lower cantilever beam 5 are deviated from each other.

The top cantilever beam 2, the upper cantilever beam 3, the middle cantilever beam 4 and the lower cantilever beam 5 are sequentially used as a ground wire, an A-phase cross arm, a B-phase cross arm and a C-phase cross arm from top to bottom.

The top cantilever beam 2, the upper cantilever beam 3, the middle cantilever beam 4 and the lower cantilever beam 5 are all in a lattice form.

The tower column of the lattice tower 1 adopts a variable cross-section steel pipe lattice rectangular column.

The tower column web members of the lattice tower 1 adopt cross rods and cross rods which are symmetrically arranged, the web members with the width surface below the tower column elevation of 10.5m adopt cross rods, and transverse partitions are arranged in the horizontal planes of the cross rods; the web members of the narrow surface of the tower column and the web members of the wide surface with the elevation of more than 10.5m adopt cross rods.

Hoop board and vertical gusset plate are established to the column node of lattice tower 1, and cross arm chord member and horizontal web member pass through the hoop board and are connected with the column, and cross arm diagonal chord member passes through vertical gusset plate with the column and is connected.

The steel pipe main rod of the tower column of the lattice tower 1 is lengthened by adopting a flange, the lower section column flange adopts a rigid flange, the upper section column flange adopts a flexible flange, and the tower column web member steel pipe is connected with the main rod steel pipe inserting plate in a single-shear manner.

Tower arrangement pattern

In a certain 750kV transformer substation project, a 330kV power distribution device is arranged in a Z shape in an outdoor GIS (geographic information System), vertical outgoing lines are adopted, in order to meet the requirement of electrical arrangement, an outgoing line framework adopts an independent tower structure, two outgoing lines are symmetrically arranged on two sides of a single tower, or a single outgoing line is arranged on one side, and a ground line and A, B, C phases are sequentially arranged from top to bottom; 8 overhanging cross arms are arranged on the single tower, 6 of the single tower are used for outgoing and hanging wires, 2 of the single tower are used for ground wire hanging wires, the height of the independent tower is 37.5m, hanging points are respectively at the elevations of 18.0m, 25.5m, 33.0m and 37.5m, the conducting wire cross arm is 5.75m overhanging from the central line of the tower column, the C phase is 5.0m overhanging from the central line of the tower column along the outgoing line direction, the A phase is 5.0m overhanging from the back of the central line of the tower column along the outgoing line direction, and the ground wire cross arm is 7.25m overhanging from the central line of the tower column. The 330kV vertical outgoing line lattice tower comprises a lattice tower, a top cantilever beam, an upper cantilever beam, a middle cantilever beam and a lower cantilever beam, wherein the top, the upper, the middle and the lower cantilever beams are staggered front and back, the top cantilever beam, the upper cantilever beam, the middle cantilever beam and the lower cantilever beam are arranged along the circumference of the lattice tower in the horizontal direction, the top cantilever beam, the upper cantilever beam, the middle cantilever beam and the lower cantilever beam are arranged from top to bottom, phase A, phase B and phase C three-phase wires and ground wires are vertically arranged in space, two outgoing lines share one base outgoing line tower, a perspective view is shown in figure 1, an elevation view is shown in figure 2, and a calculation model is shown in figure 3.

Calculating the load

Loads acting on the 330kV vertical outlet lattice tower have the effects of wire tension, wind load, ice coating load, earthquake action and temperature.

The pull force of the lead is provided by the electric specialty, the engineering outgoing line comprises a hanging 2-split LGJ-300/40 lead and a hanging 4-split LGJ-300/40 lead, the tensions of the leads are different, the same outgoing line is considered according to the possibility of hanging the two leads respectively in a long term, and the horizontal tension of the 4-split LGJ-300/40 lead is 30kN, and the vertical tension is 23 kN; 2, splitting the LGJ-300/40 wire, wherein the horizontal tension is 18kN, and the vertical tension is 12 kN; the horizontal tension of the ground wire is 10kN, and the vertical tension is 3 kN. The deflection angle of the lead and the ground wire is-5 to 45 degrees, and the deflection is far away from the tower column side.

The wind load borne by the tower is considered in the wind direction perpendicular to or parallel to the wide surface and also considered in the diagonal direction, and the wind loads in the directions of + X, -X, + Z, -Z, + X + Z, -X + Z, + X-Z and-X-Z are totally 8. The basic natural vibration period T of the general tower is more than or equal to 0.25s, the structural vibration caused by wind is obvious, and the wind vibration is enhanced along with the increase of the natural vibration period of the structure, so the influence of the wind vibration is considered during design.

The icing load on the tower is taken into account by the electrical profession in the wire pulling force.

For a relatively high-flexibility tower, the effect of wind vibration is greater than that of an earthquake, but if the structure is heavy and is located in a high earthquake intensity area, the effect of the earthquake is more intense. Therefore, when the tower is built in a high earthquake intensity area (the basic earthquake intensity of the engineering is VIII), the influence of earthquake action is considered fully to ensure the safety of the structure.

For the tower, the main structure is exposed outside, so that the influence of the temperature is direct, and meanwhile, the longitudinal size of the tower body is large, and the accumulative effect of the temperature effect is obvious. When the temperature effect is calculated, the temperature difference is reasonably selected and calculated according to the specific conditions of the engineering.

Combination of load and action

The 330kV vertical outlet lattice tower is designed by adopting a limit state design method. The extreme state design methods are divided into two types, namely, a bearing capacity extreme state and a normal use extreme state. The load-bearing capacity limit state corresponds to the deformation of the structure or structural member reaching the maximum load-bearing capacity or being not suitable for continuous load-bearing, and the normal use limit state corresponds to the structure or structural member reaching a certain specified limit value of normal use or durability; according to the wire drawing diagram, not only single-side wire hanging, but also simultaneous wire hanging on two sides are considered, meanwhile, wires of different types are hung on two sides, and 5 groups of wire load combination working conditions are required to be modeled and calculated respectively. And each group of lead load combination of each model respectively performs basic combination calculation of the load effect of the bearing capacity in the extreme state and standard combination calculation of the load effect in the extreme state in normal use with wind load, temperature action and earthquake action.

Comparison of lattice towers

The 330kV GIS vertical outgoing line framework adopts a lattice tower structure, and the two structural types of the angle steel lattice tower and the steel pipe lattice tower are discussed as follows respectively from the aspects of structural stress, structural requirements and the like:

angle steel lattice tower

The tower column adopts a variable cross-section angle steel lattice rectangular column, and an angle steel main rod, an angle steel web member and a gusset plate are connected through bolts; the framework cross arm adopts a variable-section angle steel lattice quadrilateral beam, and an angle steel chord member, an angle steel web member and a gusset plate are connected through bolts. The cross arm chord member is connected with the tower column through bolts, the whole body is in rigid connection, and the main rod of the tower column is spliced by adopting angle steel splicing joints. The angle steel lattice structure is convenient to connect, the material is easy to purchase, the production process is simple, the efficiency is high, and the defects are that the wind resistance is large, the material is stably pressed and has anisotropy, and large-specification materials are lack. When a large-scale structure with large bearing capacity needs to be designed, the combined section of the angle steel needs to be adopted, the root opening needs to be enlarged, and the arrangement and the occupied area of the electrical equipment need to be influenced when the root opening is in a large position. In addition, because the turning radius of the angle steel is smaller, in a large structure, because the length of the diagonal web members is larger, the stress of the diagonal web members is not large, and as a result, the material utilization rate is lower, and the method for solving the problem, namely reducing the slenderness ratio of the component, is to additionally arrange the subdivided web members, but the arrangement of the subdivided web members can increase the number of nodes and the steel consumption. The application of an angle steel lattice structure in a line iron tower is common. Because A, C looks cross arms have the overhanging again in the direction of being qualified for the next round of competitions in this engineering, if adopt angle steel lattice formula structure, cross arm chord member and pylon connected node are difficult to handle.

Steel pipe lattice tower

The tower column adopts a variable cross-section steel pipe lattice rectangular column, a steel pipe main rod, a steel pipe web member and a gusset plate bolt connection, the framework cross arm adopts a variable cross-section steel pipe lattice quadrilateral beam, a steel pipe chord member, an angle steel web member and a gusset plate bolt connection. The cross arm chord member is connected with the tower column through bolts, the whole body is in rigid connection, the main rods of the tower column are spliced through flanges, the structural form is convenient to obtain materials, the material specification is basically not limited, the windward body type coefficient of the steel pipe is small, the section turning radius is large, the steel pipe is isotropic, and therefore the compression stability of the rod piece is good.

Compared with an angle steel lattice structure, the steel tube lattice structure has the following advantages:

the load bearing performance of the component is good. The steel pipe member has obvious advantages as a bearing structure of a framework compared with an angle steel member. Firstly, the wind pressure of the framework can be reduced, and the shape coefficient of the circular tube component is almost doubled compared with that of the angle steel; secondly, under the condition that the cross-sectional areas are equal, the rotation radius of the round pipe is about 20 percent larger than that of the angle steel; thirdly, if a seamless steel pipe is used, the buckling coefficient is a class, and the angle steel is b class, and the difference between the buckling coefficient and the angle steel is about 7%.

Secondly, the structure stress is clear, the node structure is simple, most components belong to tension and compression rods, and the calculation assumption is met.

Good economy, generally speaking, the steel amount of the steel tube tower can be reduced by 10-20% compared with that of the angle steel tower, and the advantage of the steel tube lattice structure used for the heavy-load high tower is more obvious.

Fourthly, the appearance is beautiful. Because the steel pipe has better loaded section characteristics, namely the section characteristics in all directions are the same, the connecting node of the cross arm chord member and the tower column which are not orthogonal to the tower column is easy to process, the number of structural components is small, the section is relatively small, the pitch distance is greatly increased, and the structural arrangement is more concise and attractive.

The applicability is strong. The steel tube lattice structure has stronger applicability to frameworks with large load, large height and high voltage level.

The quality of various rolled and welded steel pipes is rapid and gradually stable, the supply channel is gradually smooth, and the steel pipes have greater advantages in specification selection.

Through the analysis, the 330kV GIS vertical outgoing line framework in the 750kV transformer substation engineering adopts a steel pipe lattice type tower structure.

Design of steel tube lattice tower

Selection of cross-sectional dimensions of steel tube lattice towers

The independent tower column preferably adopts a square section from the stress requirement, but the narrow surface direction of the tower column of the 330kV framework in the project cannot exceed 2.5m because of the influence of the interval width of outgoing lines, the wide surface along the outgoing line direction refers to the economic root opening slope H/16H of the 750kV framework column as the height of the variable section, and is determined to be 5.0m wide, the part of the width of the tower column at the elevation of 18.0m and below is reduced along with the increase of the height, and the width of the tower column at the elevation of 18.0m and above is kept unchanged by 2.5 m.

Through calculation and comparison, when 2.5m multiplied by 6.0m is adopted, the stress ratio of the rod piece is obviously reduced, the web member is basically controlled by the slenderness ratio of the compression member, and the rod material is not fully utilized; when 2.5m 4.0m openings are adopted, the stress ratio of the rod piece is obviously increased, and the stress of some web members is larger, so that the section needs to be enlarged. Therefore, the rod piece in the small root-opened tower column has larger section, the whole structure has poor permeability and clumsy appearance, and the 330kV vertical outgoing line lattice tower column in the project adopts the root-opened dimension of 2.5m multiplied by 5.0m with more harmonious integral proportion.

If the cross section size of the tower column above the elevation 18.0m is reduced from 2.5m multiplied by 2.5m to 2.0m multiplied by 2.0m, the cross section size of the cross arm is correspondingly reduced. The calculation result shows that the cross arm lower chord section of the hanging wire and the section of the tower column main rod with the elevation of more than 18.0m need to be increased by one model, the reduction of the steel quantity caused by the reduction of the section size of the tower column is offset by the increase of the steel quantity caused by the increase of the section of the main rod, and the top displacement of the tower column is increased to 120mm and exceeds the displacement limit value, so the section size of 2.5m multiplied by 2.5m is adopted for the tower column with the elevation of more than 18.0 m.

Web member type selection of steel tube lattice tower column

For a single-tower two-loop outlet wire, only one loop is hung in the current period, and two loops are hung in the long period; or two loops, one loop 2 splitting the LGJ-300/40 wire, one loop 4 splitting the LGJ-300/40 wire; or a single tower single-return line is provided, and the tower column needs to bear a large torque, so that the tower column web members adopt the cross rods and the cross rods which are symmetrically arranged, and the torsion resistance is good.

The cross web member system is often used at the short part of the rod member, and when the geometrical size of the tower column is large, the cross section of the rod member is limited due to the control of the slenderness ratio, so that the material consumption is increased. The narrow-face web members and the wide-face web members with the elevation of more than 10.5m of the 330kV vertical outlet lattice tower column in the project adopt cross rods. The cross web member system has the advantages of reducing the length-to-width ratio of the main rod, the cross rod and the diagonal rod of the tower column, and compared with the cross web member system, if the size of the tower column is the same, the length-to-width ratio of various rod members is almost halved. The wide-face web member of the 330kV vertical outlet lattice tower column with the elevation below 10.5m adopts a cross rod.

Transverse partition design of steel tube lattice tower column

The steel tube lattice tower column adopts a cross web member system on the wide surface, inclined rods are crossed at the middle points of the cross rods, and transverse partitions are added in the horizontal surface of the cross rods to maintain the stability of the cross rods outside the inclined planes of the tower. The primary function of the diaphragm is to maintain geometric invariance of the tower body plane. For the narrow face of the cross web member system, although the structure geometry can be kept unchanged without transverse partitions in principle, when the number of sides of the tower is large, the deformation resistance of the cross section of the tower body is weak for the inclined rod, or the stress of the transverse inclined rod is large when the tower column changes the slope, and the deformation resistance rigidity of the cross section of the tower body is increased by the transverse partitions.

The principle of arrangement of the transverse partitions is as follows:

firstly, a plane with an oblique rod intersection point in the middle of a cross rod requires to arrange a transverse partition in principle. If the bending stiffness of the cross bar at this point is taken into account, the reliability of the structure can only be guaranteed by making explicit calculations with the cross bar as a pull (press) bend member.

Secondly, arranging transverse partitions at the position of the tower column with a variable slope. Because the planar bar is subjected to a large force, the deformation of the planar bar is controlled to suppress the adverse effect of the nonlinear deformation.

And thirdly, transverse partitions are also arranged at intervals of 2-3 layers under other conditions so as to reduce the adverse effect of the plane deformation of the tower.

Fourthly, corresponding transverse partitions are arranged on the tower columns at the positions of the diagonal rods with the subdivided web members.

2 the arrangement of the transverse partitions in the horizontal plane is as follows:

firstly, connecting each node in the plane into a plane truss with unchanged geometry.

② the calculated length of the transverse septum is reduced as much as possible.

3 calculation of stress at diaphragm

The diaphragm is generally less stressed and is controlled mainly according to the conditions of slenderness ratio when selecting the section, so that the structure is more economical. As a secondary component of the tower, the slenderness ratio of the transverse partitions can be controlled within 120-200, and the slenderness ratio in two directions is required to be basically balanced so as to avoid material waste caused by too large slenderness ratio in one direction. Therefore, when the material of the transverse partitions is selected, the rigid transverse partitions are made of steel pipes, the flexible transverse partitions are made of round steel, when the length of the transverse partitions is short, single angle steel or double angle steel can be used, the material of the angle steel is low in cost, and the connection is convenient.

The calculation of the diaphragm is carried out as much as possible according to the actual arrangement condition, the diaphragm is considered when the main structure is modeled, and the real internal force of the diaphragm rod piece is determined through the whole space calculation of the structure. Since the diaphragms also have dead weight and other lateral loads in use, or bear mounting loads, the bending secondary stress of the diaphragms should be properly considered in the calculation.

4 transverse partition connection

The transverse partitions are used as secondary rod pieces of the tower, generally, the stress is small, so that the stress of the nodes is also small, and double-shear connection and single-shear connection are generally adopted. Wherein, the main transverse partition adopts double-shear connection, and the secondary transverse partition adopts single-shear connection. When the diaphragm and the cross rod are crossed at a certain point on the tower column together, the cross rod is easy to interfere with the diaphragm, the diaphragm and the diaphragm, the connection of the cross rod is guaranteed at the moment, the main diaphragm is adopted, and the secondary diaphragm is considered at last.

Cross arm design of steel tube lattice tower

Referring to fig. 1, 2 a-2 e, the cross arm is an overhanging structure with triangular arranged chords, and the top and bottom surfaces of the cross arm are provided with cross web members. The A-phase cross arm and the C-phase cross arm are respectively calculated by two structural types:

1 the upper chord is connected in a straight line from the column body of the tower column to the end part of the cross arm without a bending point, the cross section of the cross arm is in a dissimilar right trapezoid, the top surface crossed web members are not in the same plane and are not connected with each other, the length-thin ratio of the web members is large, and refer to fig. 4.

2, arranging a lattice type support similar to a triangular prism at the column body of the tower column, connecting the support to the end part of the cross arm in a straight line, and bending the upper chord at the support, as shown in fig. 5. The cross section of the cross arm is similar to a rectangle, the top surface crossed web members are on the same plane, the cross points can be connected, the slenderness ratio outside the plane of the web members is calculated by adopting the gyration radius ix of a shaft parallel to the limb sides of the angle steel, the minimum gyration radius iv of the angle steel is adopted in 1, ix is basically 1.5 times of the minimum gyration radius iv of the angle steel, and the slenderness ratio of the web members is about 2/3 of the slenderness ratio of the corresponding member members in 1, so the cross section of the top surface web members is reduced. The vertical web members and the inclined web members on the plane where the cross arm upper chord folding rods are located are increased, and the total steel amount is reduced by 0.2 percent. However, the whole structure is heavier than the 1 type, and the upright surface of the frame tower is compared with that shown in figures 6 and 7, so that the A, C cross arm adopts the 1-in-1 structure type.

Design of connection node

The strength, stable calculation and structural design of the connection node are important links in the whole design work. The design of the connection node is actually the process of the hypothetical implementation of the rod-end connection in the structural model. Whether the design is reasonable or not plays an important role in ensuring whether the actual structure is consistent with the calculation model or not, whether the rod piece can definitely transfer force according to requirements or not and structural integrity.

The following principles are required to be followed when calculating and constructing the connection node:

the internal force transmission at the connecting node is simple, convenient and clear, safe and reliable, and the additional bending moment caused by eccentricity is reduced as much as possible.

Secondly, the connecting joint is ensured to have enough strength and rigidity.

And the node is simple to process and convenient to construct and install.

According to the statistical result of the prior engineering frame steel, the proportion of the gusset plate steel accounting for the total weight of the frame steel is about 40-50%, so the node calculation and the reasonable selection of the gusset plate have great influence on the appearance and the steel consumption of the frame.

Tower column node type:

referring to fig. 8 a-8 e, the main rods of the lattice tower steel pipes are extended by flanges, and the flange connection belongs to a part of rigid connection nodes. The lower section column flange with larger stress adopts a rigid flange, and the upper section column flange with smaller stress adopts a flexible flange. The connection modes of the tower column web member steel pipe and the main rod steel pipe comprise pipe-pipe intersecting line welding, U-shaped inserting plate double-shear connection and inserting plate single-shear connection.

The tubular intersecting line welding is shown in fig. 8a, belongs to a part of rigid joint, and has the advantages of high connection rigidity, no need of auxiliary connection materials and high connection strength; the method has the defects that the requirement on processing equipment is high, a numerical control intersecting line cutting machine is preferably used, a groove is cut simultaneously, the welding work is complicated, particularly, the requirement on butt welding is difficult to meet for a welding line at an acute angle intersection, and cracks are easy to generate under the action of large repeated load. When the weld is thick, the influence of welding stress and welding deformation is also large. Besides checking the welding seam, the intersecting line welding also needs to pay attention to the lateral stability and strength of the main pipe wall after stress, and the factors such as the diameter of the main pipe and the secondary pipe, the wall thickness ratio and the like need to be comprehensively considered.

The U-shaped inserting plate double-shear connection is shown in figure 8b, belongs to a hinged joint and is used for connecting an inclined web member and a transverse partition, and the U-shaped inserting plate connection has smaller lateral rigidity but saves materials. The stress process of the U-shaped inserting plate connection is as follows: the web member steel pipe transmits force to the U-shaped plate through the welding seam, the U-shaped plate transmits force to the middle inserting plate through shearing resistance of the bolt, and the inserting plate transmits force to the main rod through the welding seam. The stiffening plate plays a role in reinforcing the lateral rigidity. When the section of the web member steel pipe is too small, the damage to the net section of the steel pipe is too large when the U-shaped plate is inserted, and the connection by the U-shaped plate is not suitable. The U-shaped flashboard double-shear connection is inserted smoothly when guaranteeing the installation, and the U-shaped plate clearance should increase 1 ~ 2mm than mobile jib gusset plate thickness.

The single-shear connection of the inserting plate is shown in a figure 8d, belongs to a hinged joint and is used for connecting an inclined web member with small stress and a transverse partition, the section of the steel pipe at the position is often determined by the allowable slenderness ratio, the internal force is small, and therefore the strength requirement can be met by using the single-shear connection of the bolt. The single shear connection is eccentric generally, so the strength and stability of the connection and the rod piece are reduced according to the standard. The end part of the web member steel pipe is provided with a groove-shaped inserting plate or a T-shaped inserting plate according to the internal force. Because the compression web member steel pipe is generally controlled by integral stability, under the condition of ensuring that the net section compression and the hole wall pressure-bearing of the inserting plate meet the requirements, the inserting plate and the compression web member steel pipe are conservative if the inserting plate and the compression web member steel pipe are arranged by adopting equal area conversion.

Design of connecting joint of tower column and cross arm

The latticed tower column and the cross arm are integrally and rigidly connected, and the cross arm upper chord and the cross arm lower chord, the vertical face of which is triangular, are hinged with the tower column through node plates by common bolts. The hoop plates are arranged at the nodes of the tower column and are used as connecting plates of horizontal web members, cross partitions, cross arm chord members and web members of the tower column on one hand, and the torsional rigidity of the main rod of the tower column on the other hand is enhanced. And for the A-phase cross arm and the C-phase cross arm, the included angle between the A-phase cross arm and the C-phase cross arm in the horizontal plane and the axis of the tower column along the outgoing line direction is 42 degrees, the B-phase cross arm and the ground wire cross arm are 90 degrees, and the annular plates are adopted to be conveniently connected with the cross arm chords in all directions. The cross arm inclined chord members are connected with the tower column through the vertical gusset plates, the circumferential plates serve as stiffening plates of the gusset plates to play a role in strengthening lateral rigidity, and partial gusset plate connections are shown in fig. 9a, 9b, 9c and 9d in detail.

Comparing the vertical outlet lattice tower with the inverted Y-shaped column gantry framework with the end support

The arrangement size of the vertical outlet lattice tower is compared with that of the inverted V-shaped column gantry framework with the end support

The arrangement dimension of the vertical outlet lattice tower along the direction vertical to the outlet line is 1.25+31.0 × 5+46.0+31.0 × 6+1.25 ═ 389.5m, while the arrangement dimension of the herringbone gate type framework with the end support along the direction vertical to the outlet line is 4.5+18.0 × 6+5.0+18.0 × 4+18.0+18.0 × 6+5.0+18.0 × 6+4.5 ═ 433.0m, which is increased by 43.5m compared with the vertical outlet tower.

Comparison of the amount of rigid dismantling of the straight-out lattice tower and the gate-type frame with end-support herringbone columns

Under the same external condition and the same wire tension, two structural types of a vertical outlet lattice tower and a herringbone column door-shaped framework with end supports are respectively modeled and calculated, and the statistical results of the steel quantity are shown in tables 1 and 2:

TABLE 1 amount of steel for vertical outlet lattice tower

Serial number	Name of component	Number of	Single weight (kg)	Total weight (t)	Remarks for note
						1	GJT-1	7	24891.1	174.24	Lattice tower
2	GJT-2	2	20234.4	40.47	Lattice tower
						3	GJT-2a	1	18673.4	18.67	Lattice tower
4	GJT-2b	1	18664.3	18.66	Lattice tower
						5	GJT-3	2	26231.4	52.46	Lattice tower
6	Ladder stand	13	577.4	7.51
							Total up to			312.01

TABLE 2 Steel amount for gate-type framework with end brace herringbone post

From the two tables, the steel quantity of the vertical outlet lattice tower is reduced by 27.08t compared with the steel quantity of the end support herringbone column door type framework, the steel unit price is calculated according to 9300 yuan/t, and the cost is saved by 25.2 ten thousand yuan.

Comparison of two structural types of reinforced concrete bearing platforms

The statistical results of the reinforced concrete bearing platform are shown in tables 3 and 4:

TABLE 3 concrete amount of bearing platform of lattice tower with vertical outlet

TABLE 4 concrete content of bearing platform with end-supported herringbone column gantry framework

As seen from tables 3 and 4, the amount of the bearing platform concrete of the vertical outlet lattice tower is reduced by 81.6m3 compared with the amount of the bearing platform concrete of the portal frame with the end support herringbone columns, the unit price of the reinforced concrete is calculated according to 600 yuan/m 3, and the cost is saved by 4.9 ten thousand yuan.

Comparison of pile foundations of two structural types

The pile foundation statistics of the bearing platform are shown in tables 5 and 6:

TABLE 5 pile number of bearing platform of vertical outlet lattice tower

Serial number	Name of component	Number of	Single group pile cap number	Total pile number (root)	Remarks for note
						1	GJT-1 bearing platform	7	8	56
2	GJT-2 bearing platform	2	8	16
						3	GJT-2a bearing platform	1	8	8
4	GJT-2b bearing platform	1	8	8
						5	GJT-3 bearing platform	2	8	16
	Total up to			104

TABLE 6 pile number of bearing platform with end-supported herringbone column gantry framework

Serial number	Name of component	Number of	Single group pile cap number	Total pile number (root)	Remarks for note
						1	GZ-1 bearing platform	4	12	48
2	GZ-2 bearing platform	22	6	132
							Total up to			180

It is seen from tables 5 and 6 that the number of pile foundations of the vertical outlet lattice tower is reduced by 76 compared with the number of pile foundations of the end-supported herringbone pillar gantry frame, and the unit price of the pile foundations is calculated according to 9043 yuan per pile, so that the cost is saved by 68.7 ten thousand yuan.

Through the comparison of the steel quantity, the concrete quantity and the pile number of the bearing platform of the two structural types, which are combined into the economic cost, the cost of the vertical outlet lattice tower is saved by 25.2+4.9+ 68.7-98.8 ten thousand yuan compared with the herringbone column door-shaped framework body with the end support. And the former compares the latter and saves 43.5m wide occupation of land along being perpendicular to the direction of being qualified for the next round of competitions, approximately amounts to 3.3 mu, and the unit price is calculated according to 36 ten thousand yuan/mu, saves the expense 118.8 ten thousand yuan.

In conclusion, the cross arm and the tower column of the vertical outlet latticed tower adopt a steel pipe latticed structure convenient for node connection, the tower column adopts a steel pipe main rod and a steel pipe web member which are connected through a node plate bolt, the web member adopts a cross rod or a cross rod with good torsion resistance or a cross rod with a shape like a Chinese character 'mi', and the end part of the web member is provided with a groove-shaped inserting plate which is connected with the node plate in a single shearing mode. The cross arm is connected by steel pipe chord members, angle steel web members and gusset plate bolts, and the inner chord members of the vertical face of the cross arm are arranged in a triangular mode. A. C, the upper chord of the cross arm is linearly connected from the column body of the tower column to the end part of the cross arm without bending, the cross section of the cross arm is in a dissimilar right trapezoid shape, the top surface cross web members are not on the same plane and are not connected with each other, the bottom surface web members are arranged in a crisscross manner, and the cross parts are connected through bolts; the cross sections of the B-phase ground wire cross arms are similar rectangles, web members on the top and bottom surfaces are arranged in a cross way, and the cross positions are connected through bolts. The root of the tower column is calculated and selected to be 2.5m multiplied by 0m, the main material of the steel tube at the foot of the tower column is phi 273 multiplied by 10-phi 273 multiplied by 14, the web member is phi 114 multiplied by 5-phi 121 multiplied by 6, and the appearance is harmonious in proportion.

The calculated deflection of the top of the tower column and the calculated deflection of the end parts of the cross arms in the vertical and horizontal directions all need to meet the requirement of a limit value. The ground wire on the cross arm chord member is provided with a horizontal hole hanging ring plate, the wire is provided with a vertical hole hanging ring plate, and the orientation of the hanging ring plate is rotated, so that the included angle between the hanging ring plate and the cross arm chord member meets the space requirement of wire hardware fitting installation, and meanwhile, the torsion effect generated by the eccentricity of the hanging hole at the end part of the cross arm is reduced.

Compared with a herringbone column door type framework with end supports, the vertical outlet lattice tower saves the cost of the body by 98.8 ten thousand yuan compared with the latter and occupies about 19 percent of the cost of the body of the latter, and the former saves the occupied land of 43.5m in width along the direction vertical to the outlet wire compared with the latter and occupies about 3.3 mu, the unit price is calculated according to 36 ten thousand yuan/mu, and the cost is saved by 118.8 ten thousand yuan.

Moreover, the lattice tower that is qualified for next round of competitions perpendicularly installs and overhauls relatively independently, has avoided the risk of mutual restriction and error accumulation between the beam column when the door type framework is assembled, overhauls, reforms transform can not reach other being qualified for the next round of competitions. Meanwhile, the conventional structural form of a door-shaped framework with end-supporting herringbone columns is adopted when the traditional horizontal outgoing line of the transformer substation is overturned, and a tower structure which is another structural form of the outgoing line framework design is provided. For other voltage-class vertical outgoing line arrangement schemes in compact arrangement, the optimized outgoing line structure design has good reference significance. The technical proposal also has good reference significance for the structural design of the line tower hanging the lines along different directions in space, in particular to the design of the connecting node of the cross arm and the tower body.

Claims

1. The utility model provides a lattice tower outlet structure, its characterized in that, including lattice tower (1), top cantilever beam (2), upper portion cantilever beam (3), middle part cantilever beam (4) and lower part cantilever beam (5) are arranged along a week of lattice tower (1) on the horizontal direction, top cantilever beam (2), upper portion cantilever beam (3), middle part cantilever beam (4) and lower part cantilever beam (5) are arranged from top to bottom, make A looks, B looks, C looks three-phase wire and ground wire arrange perpendicularly in space, two outgoing lines share one base outgoing line tower.

2. The lattice tower type wire outlet structure according to claim 1, wherein the top cantilever beam (2) and the middle cantilever beam (4) are arranged in a straight line, and the length of the top cantilever beam (2) is greater than that of the middle cantilever beam (4); the upper cantilever beam (3) and the lower cantilever beam (5) are arranged in a V shape, and the opening directions of the upper cantilever beam (3) and the lower cantilever beam (5) are deviated from each other.

3. The lattice tower type wire outlet structure according to claim 1, wherein the top cantilever beam (2), the upper cantilever beam (3), the middle cantilever beam (4) and the lower cantilever beam (5) are sequentially used as a ground wire, an A phase, a B phase and a C phase cross arm from top to bottom.

4. The lattice tower type outlet structure according to claim 3, wherein the upper chords of the A-phase cross arm and the C-phase cross arm are in a straight line shape from the lattice tower body to the end of the cross arm, and the cross arms are in a cross section of a dissimilar right trapezoid; the cross sections of the phase B and the ground wire cross arm are similar rectangles.

5. The lattice tower type line outgoing structure of claim 3, wherein the cantilever beam vertical faces used by the A phase and the C phase are both triangular; the top cross web members are not in the same plane, and the top web members are not connected to each other.

6. The lattice tower type wire outlet structure according to claim 1, characterized in that the top cantilever beam (2), the upper cantilever beam (3), the middle cantilever beam (4) and the lower cantilever beam (5) are all lattice type.

7. The lattice tower type outlet structure according to claim 1, characterized in that the tower columns of the lattice tower (1) are steel tube lattice rectangular columns with variable cross-sections.

8. The lattice tower type wire outlet structure according to claim 1, wherein the tower column web members of the lattice tower (1) adopt cross bars and cross bars which are symmetrically arranged, the web members of the wide surface below the tower column elevation of 10.5m adopt cross bars, and transverse partitions are arranged in the horizontal planes of the cross bars; the web members of the narrow surface of the tower column and the web members of the wide surface with the elevation of more than 10.5m adopt cross rods.

9. The lattice tower type wire outlet structure according to claim 1, wherein a hoop plate and a vertical gusset plate are arranged at a tower column node of the lattice tower (1), the cross arm chord member and the horizontal web member are connected with the tower column through the hoop plate, and the cross arm diagonal chord member is connected with the tower column through the vertical gusset plate.

10. The lattice tower type outlet structure according to claim 1, wherein the steel pipe main rods of the tower columns of the lattice tower (1) are extended by flanges, the flanges of the lower section columns are rigid flanges, the flanges of the upper section columns are flexible flanges, and the steel pipe web members of the tower columns are connected with the steel pipe inserting plates of the main rods in a single shearing mode.