Double-row steel cable variable-pitch joint and installation method thereof

Abstract

The application discloses a double-row steel cable variable-pitch joint and a mounting method thereof, and the joint comprises a plurality of interval arranged cable clamps, each cable clamp comprises an upper clamp plate, a lower clamp plate and a plurality of hexagon bolts, a corresponding semicircular cable path is formed on the upper clamp plate and the lower clamp plate, and the middle part of the cable path is a curved arc segment, and the two ends of the cable path are provided with outwardly expanded chamfers. The application can realize variable pitch under the condition that the running direction of the steel cable is changed by a very small angle, greatly reduces the extrusion force of the steel cable on the cable path due to the angle change, and reduces the risk of damage of the cable clamp; the size of the cable clamp of the double-row steel cable variable-pitch joint is much smaller than that of the traditional variable-pitch joint, that is, the construction cost is saved, and the appearance requirement of the building is considered; the double-row steel cable variable-pitch joint does not need to be bent by a large angle when the steel cable is embedded into the cable path, the installation difficulty is low, the efficiency is high, and the construction progress can be effectively ensured.

Description

Technical Field

[0001] This invention relates to the field of building steel structure technology, specifically to a double-row steel cable variable pitch node and its installation method. Background Technology

[0002] Cable structures are widely used in construction engineering due to their advantages such as light weight, short construction period, and high flexibility in architectural appearance. Currently, in some projects, the spacing between the end connecting lugs of double-row steel cables differs from the spacing between the steel cables themselves. Therefore, special nodes are often used to adjust the spacing at the cable ends, ensuring that the cable heads can be smoothly installed onto the lugs.

[0003] Traditional variable-pitch joints typically involve installing a large cable clamp at the end of the steel cables. By creating a near-zigzag cableway inside the clamp, the cableway forces a change in the cable's trajectory. The double-row steel cables enter the cableway with their original pitch, and after being forced to change direction, exit with a pitch equal to the spacing between the ear plates, thus achieving the variable-pitch effect. However, the tension of the steel cables is often high. Forcibly changing the cable's trajectory causes significant compressive stress on the cableway within the clamp, and this stress is directly proportional to the maximum bending angle of the cable within the cableway. Excessive compressive stress can damage the clamp's connecting bolts, leading to safety accidents. To reduce this compressive stress, the bending angle of the steel cables within the cableway must be reduced. For traditional variable-pitch joints, this can only be achieved by increasing the size of the cable clamp. However, excessively large clamps inevitably affect the building's aesthetics, increase construction costs, and result in unnecessary waste. Therefore, it is essential to propose an economical and safe variable-pitch node and installation method that only requires the steel cable to be bent at a very small angle within the cable clamp. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides a double-row steel cable variable pitch node and its installation method, which reduces the squeezing pressure of the steel cable on the cable clamp channel and reduces the size of the cable clamp, thus ensuring both safety and economy while also taking into account the aesthetics of the building.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a double-row steel cable variable pitch node, comprising a number of cable clamps arranged at intervals, each cable clamp comprising an upper clamp plate, a lower clamp plate and a number of hexagonal bolts, wherein the upper clamp plate and the lower clamp plate are provided with corresponding semi-circular cable tracks, wherein the middle of the cable track is a short curved arc segment and both ends are provided with outwardly flared chamfers.

[0006] Furthermore, the inner diameter of the semi-circular cableway is slightly larger than the radius of the steel cable, and the depth of the cableway is slightly smaller than the radius of the steel cable.

[0007] Furthermore, the inner surface of the cableway is treated with a frosted finish to increase the coefficient of friction between the side surface and the steel cable.

[0008] Furthermore, the hexagonal bolt adopts a through-type design, which ensures load-bearing capacity while reducing processing difficulty.

[0009] Furthermore, the upper and lower clamping plates employ the same anti-corrosion process, reducing processing difficulty.

[0010] The upper and lower clamping plates are designed according to the diameter of the steel cable to ensure that, after the upper and lower clamping plates are fixed, the spacing between the clamping plates is greater than the sum of the deformation of the upper and lower clamping plates when the hexagonal bolts are tightened. The cableway entrances, exits, and sides need to be chamfered to prevent stress concentration. The cableway route uses an arc shape to allow the steel cable to turn smoothly. For the large hexagonal bolts, within the allowable range of anti-slip bearing capacity, the preload of the hexagonal bolts at the cable corners, which mainly bear the compressive force of the steel cable on the cableway, can be appropriately reduced.

[0011] A method for designing and installing a node with variable pitch for double-row steel cables, mainly including the following steps (taking a node with only two cable clamps as an example):

[0012] (1) The two variable-pitch cable clamps are located between the steel cable anchor head and the first cable strut node. Therefore, the maximum spacing between the two variable-pitch cable clamps is determined based on the spacing between the steel cable anchor head and the first cable strut node and the building appearance requirements. The installation position of the cable clamps is marked on the steel cable.

[0013] (2) Calculate the minimum deflection angle of the cableway relative to the original steel cable direction based on the maximum spacing of the variable cable clamps;

[0014] (3) Calculate the horizontal component of the steel cable based on the pretension of the steel cable and the deflection angle of the cableway. The horizontal component acts on the cableway, causing the upper and lower clamps of the cable clamp to produce a splitting effect, which ultimately acts on the hexagonal bolts.

[0015] (4) Calculate the required preload of the hexagonal bolts based on the anti-slip bearing capacity requirements of the cable clamp;

[0016] (5) Select the hexagonal bolt specifications based on the preload of the hexagonal bolts and the horizontal component of the force generated by the steel cable;

[0017] (6) Install the first cable clamp at the marked position and embed the steel cable into the cableway along the cableway direction, so that the steel cable changes from a parallel state to a figure-eight direction. The cable pitch of the steel cable naturally expands between the two cable clamps. Then, pre-tighten the hexagonal bolts of the cable clamp.

[0018] (7) Install the second cable clamp at the marked position and embed the steel cable into the cableway along the cableway direction, so that the steel cable changes from the "eight" shape to a parallel state. Then tighten the hexagonal bolt of the cable clamp. At this time, the spacing between the steel cables has been naturally expanded or reduced between the two cable clamps, and the cable spacing has been adjusted to the correct position.

[0019] (8) After confirming that the cable clamp is installed correctly, tighten all the large hexagonal bolts according to the predetermined preload. The installation of this node is now complete.

[0020] The principle of this invention is to slightly alter the direction of the two steel cables using a first clamp, causing them to form a figure-eight shape. This allows the distance between the cables to naturally increase or decrease. Then, a final clamp is used to change the cable direction from a figure-eight shape to a parallel state. When the cable distance change is small, only two clamps are needed to adjust the cable distance. When the cable distance change is large, the number of clamps can be increased. Specifically, when the steel cable enters the second clamp, the second clamp again slightly alters the cable direction, further increasing the angle between the two cables, and the speed at which the distance between the cables naturally increases after exiting the cableway also increases. This process is repeated until the cable distance increases to a certain extent. Then, using the above method, multiple clamps are placed at intervals to gradually decrease the angle between the two rows of steel cables until the figure-eight shape slowly returns to a parallel state. This invention has the following beneficial effects:

[0021] (1) The double-row steel cable variable pitch node proposed in this invention can achieve variable pitch by changing the angle of the steel cable direction by a very small amount, which greatly reduces the squeezing force on the cableway caused by the bending angle of the steel cable and reduces the risk of cable clamp damage.

[0022] (2) The cable clamp size of the double-row steel cable variable pitch node provided by the present invention is much smaller than that of the cable clamp size of the traditional variable pitch node, which saves construction costs and also takes into account the building appearance requirements.

[0023] (3) The double-row steel cable variable pitch node provided by the present invention does not require large-angle bending of the steel cable when it is embedded in the cableway, which is easy to install, efficient and can effectively ensure the construction progress. Attached Figure Description

[0024] Figure 1 This is an exploded view of the components of the present invention;

[0025] Figure 2 This is a schematic diagram of the installation of the present invention;

[0026] Figure 3 This is a side view of the cable clamp structure of the present invention;

[0027] Figure 4 The top view of the lower clamping plate structure in the cable clamp of this invention is shown in the figure.

[0028] Figure 5 for Figure 2 Axonometric view. Detailed Implementation

[0029] Reference Figures 1 to 5 This paper further describes a specific embodiment of the double-row steel cable variable pitch node and its installation method according to the present invention. This embodiment uses the method of achieving variable pitch by setting only two variable pitch clamps as an example to further describe the present invention.

[0030] A type of double-row steel cable variable pitch node, such as... Figure 1 As shown, the system includes the following components: variable pitch cable clamp 1 (No. 1) and variable pitch cable clamp 2 (No. 2). Each variable pitch cable clamp consists of an upper clamp plate 3, a lower clamp plate 4, and hexagonal bolts 5. The upper and lower clamp plates can be machined from steel plates or cast integrally from cast steel. A slot is cut in the middle of the upper and lower clamp plates to form the cableway 6. After the steel cable 8 is embedded in the cableway, its direction deflects, with the deflection angle controlled within 1°, which can be calculated based on the actual stress conditions. High-strength large hexagonal bolts 5 are used to connect the upper and lower clamp plates; the number of bolts is determined according to the anti-slip bearing capacity requirements of the cable clamp.

[0031] The inner diameter of the semi-circular cableway 6, located between the upper clamping plate 3 and the lower clamping plate 4, is slightly larger than the radius of the steel cable. This ensures that the inner wall of the cableway 6 is completely in contact with the surface of the steel cable when the clamping plates hold the steel cable in place. The depth of the cableway 6 is slightly less than the radius of the steel cable to ensure that there is still a certain gap between the upper and lower clamping plates after the large hexagonal bolts 5 are tightened.

[0032] like Figure 4 As shown, cableway 6 consists of three sections. Sections 6-a and 6-c follow the same direction as the steel cable entering and exiting the cableway. Section 6-b is a curved section. After the steel cable passes through this curved section, it makes a turn of angle α. The center points of sections 6-a and 6-c are tangent to the center line of section 6-b.

[0033] The cableway entrances and exits 6 and 11, as well as the sides, are all chamfered to avoid stress concentration.

[0034] After the upper clamping plate 3 and the lower clamping plate 4 are tightened with the large hexagonal bolt 5, a gap of about 8-10mm should still be maintained.

[0035] The inner walls of the cableway 6 in the upper clamping plate 3 and the lower clamping plate 4 need to be sanded to increase the friction coefficient between the cableway 6 and the steel cable contact surface.

[0036] Several bolt holes 9 are opened on both sides of the cableway 6 in the upper clamping plate 3 and the lower clamping plate 4. The number of bolt holes 9 is determined according to the required number of bolts based on the anti-slip bearing capacity requirements of the cable clamp.

[0037] The dimensions L5 and L6 of cable clamp 1 and cable clamp 2 are determined according to the required number of bolts and the requirements of the bolt connection structure.

[0038] The inlet spacing of the steel cables of the two cableways 6 in cable clamp 1 is L1 and the outlet spacing is L2. The inlet spacing of the steel cables of the two cableways 6 in cable clamp 2 is L3 and the outlet spacing is L4, where L1 < L2 < L3 < L4.

[0039] The preload of the hexagonal bolt 5 is calculated and determined based on the anti-slip bearing capacity requirements of the cable clamp.

[0040] The specifications of the hexagonal bolt 5 are determined based on its preload and the compressive force exerted by the steel cables 8 and 10 on the cableway. The compressive force exerted by the steel cables 8 and 10 on the cableway is determined by the angle α between the cableway 6 and the steel cables 8 and 10.

[0041] At the corner of the steel cable 8, that is, at the junction of cableway 6-a and 6-b of cable clamp 1 and the junction of cableway 6-c and 6-b of cable clamp 2, the preload of the large hexagonal bolt 5 can be appropriately reduced within the allowable range of anti-slip bearing capacity.

[0042] During the node design and installation, first determine the deflection angle of the steel cable after it passes through the cableway, based on the maximum allowable spacing between the two variable-pitch cable clamps. The deflection angle is inversely proportional to the spacing between the two cable clamps; within the allowable spacing range, the deflection angle should be as small as possible. Then, determine the specifications and preload of the high-strength bolts based on the deflection angle, the preload of the steel cable, and the anti-slip bearing capacity requirements of the cable clamps. Finally, install the two cable clamps in their corresponding positions, embed the steel cable into the cableway, and tighten the large hexagonal bolts to the predetermined preload. At this point, the node design and installation are complete.

[0043] A node and installation method for double-row steel cable with variable pitch, mainly including the following steps:

[0044] (1) Based on the building appearance requirements and the distance between the steel cable anchor head and the first support rod, calculate the maximum distance L7 between cable clamp 1 and cable clamp 2, and mark the installation positions of cable clamp 1 and cable clamp 2 on the steel cable.

[0045] (2) Based on the difference between the steel cable pitch before and after adjustment: L4-L1, and the distance between the two variable pitch cable clamps L7, calculate the minimum turning angle α generated by the steel cable in cableway 6: α = arctan[(L3-L2) / 2*L7];

[0046] (3) Calculate the number of bolts n required for the cable clamp and the preload F1 of the large hexagonal bolt 5 according to the anti-slip bearing capacity requirements of the cable clamp;

[0047] (4) Calculate the horizontal component force F3 = F2 * sinα generated by the steel cable due to the rotation angle based on the pretension F2 of the steel cable and the rotation angle α of the steel cable in the cableway;

[0048] (5) Based on the horizontal component force F3 of the steel cable and the preload force F1 of the large hexagonal bolt 5, select the specifications of the large hexagonal bolt so that it can withstand the combined action of F3 and F1. The force of F1 is considered to be borne by a single bolt at the corner position. The calculation method refers to the anti-splitting verification of the end of the pin lug plate. Within the allowable range of anti-slip bearing capacity, the preload force of the bolt is:

[0049] (6) Install cable clamp 1 to the designated position, embed steel cable 8 into cableway 6, and then pre-tighten large hexagonal bolt 3. At this time, the steel cable enters cableway 6 at a distance of L1 and exits cableway 6 at a distance of L2. The double-row steel cables change from the previous parallel state to a figure-eight pattern, and the included angle between the two is 2α.

[0050] (7) The steel cable 8 naturally expands within the range of the distance L7 between the two variable cable clamps, and the distance increases from L2 to L3;

[0051] (8) Install cable clamp 2 to the designated position, embed steel cable 8 into cableway 6, and then pre-tighten large hexagonal bolt 3. At this time, the steel cable enters cableway 6 at a spacing of L3 and exits cableway 6 at a spacing of L4. The double-row steel cable changes from the previous figure-eight pattern to a parallel state.

[0052] (9) After confirming that the node installation is correct, tighten the large hexagonal bolts according to the predetermined preload. At this point, the node installation of the double-row steel cable with variable pitch is completed, and the steel cable with variable pitch is completed.

[0053] (10) The above steps are the design and installation method for expanding the spacing of double-row steel cables. By swapping the positions of cable clamp 1 and cable clamp 2, the function of reducing the spacing of double-row steel cables can be realized.

[0054] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for installing a node with variable pitch of double-row steel cables, characterized in that, The node includes several cable clamps spaced apart. Each cable clamp includes an upper clamp plate, a lower clamp plate, and several hexagonal bolts. The upper clamp plate and the lower clamp plate have corresponding arc-shaped cableways. The middle section of the cableway is a curved section, and both ends are provided with outwardly flared chamfers. The radius of the arc-shaped cableway is larger than the radius of the steel cable, and the depth of the cableway is smaller than the radius of the steel cable. When setting up two cable clamps, the main steps are as follows: (1) The two variable-pitch cable clamps are located between the steel cable anchor head and the first cable strut node. Therefore, the maximum spacing between the two variable-pitch cable clamps is determined based on the spacing between the steel cable anchor head and the first cable strut node and the building appearance requirements. The installation position of the cable clamps is marked on the steel cable. (2) Calculate the minimum deflection angle of the cableway relative to the original steel cable direction based on the maximum spacing of the variable cable clamps; (3) Calculate the horizontal component of the steel cable based on the pretension of the steel cable and the deflection angle of the cableway. The horizontal component acts on the cableway, causing the upper and lower clamps of the cable clamp to produce a splitting effect, which ultimately acts on the hexagonal bolts. (4) Calculate the required preload of the hexagonal bolts based on the anti-slip bearing capacity requirements of the cable clamp; (5) Select the hexagonal bolt specifications based on the preload of the hexagonal bolts and the horizontal component of the force generated by the steel cable; (6) Install the first cable clamp at the marked position and embed the steel cable into the cableway along the cableway direction, so that the steel cable changes from a parallel state to a figure-eight direction. Then, pre-tighten the hexagonal bolts of the cable clamp. (7) Install the second cable clamp at the marked position and embed the steel cable into the cableway along the cableway direction, so that the steel cable changes from the "eight" shape to a parallel state. Then tighten the hexagonal bolt of the cable clamp. At this time, the spacing between the steel cables has been naturally expanded or reduced between the two cable clamps, and the cable spacing has been adjusted to the correct position. (8) After confirming that the cable clamp is installed correctly, tighten all the hexagonal bolts according to the predetermined preload. The installation of this node is now complete.

2. The installation method of the node with variable pitch of double-row steel cables according to claim 1, characterized in that: The inner surface of the cableway is frosted to increase the coefficient of friction between the side and the steel cable.

3. The installation method of the node with variable pitch of double-row steel cables according to claim 1, characterized in that: The hexagonal bolts adopt a through-type design.

4. The installation method of the node with variable pitch of double-row steel cables according to claim 1, characterized in that: The upper and lower clamping plates use the same anti-corrosion process, reducing processing difficulty.

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