A device for two-way tension connection of prestressed steel tendons at the mid-span of a prestressed box girder

Abstract

The present invention provides a device for bidirectional tensioning connection of prestressed steel bundles in the mid-span of a prestressed box girder, comprising two prestressed steel bundles arranged oppositely, and also comprising a bracket arranged above the prestressed steel bundle; a connecting assembly, the connecting assembly comprising two fixed sleeves arranged oppositely on the bracket, the fixed sleeves being slidably connected to the bracket, the bottom end of the fixed sleeves being connected to a rotating pull rod, the bottom end of the rotating pull rod being provided with an opening and closing piece, the opening and closing piece having a clamping end and a clamping end; a connecting anchor, arranged at the end of the prestressed steel bundle, the connecting anchor being detachably connected to the rotating pull rod through the clamping end and the clamping end; a tensioning piece, the tensioning piece being arranged between the two rotating pull rods, the two rotating pull rods being rotated toward each other along the coaxial line through the tensioning piece. The present invention can realize the tensioning of the prestressed steel bundle at the mid-span position inside the prestressed box girder, and can play a role when there is no tensioning space at the beam end, the tensioning conditions are limited, and the construction period is tight.

Description

Technical Field

[0001] The invention belongs to the technical field of steel bundle tensioning, and in particular relates to a device for bidirectional tensioning and connecting prestressed steel bundles in the mid-span of a prestressed box girder. Background Art

[0002] In the field of bridges, prestressing has been widely used. Before the bridge is subjected to external loads, prestressed steel strands are set in the tension area to give full play to the characteristics of high-strength materials, improve the bending resistance and stiffness of the components, delay the appearance of cracks, and improve the durability of the components.

[0003] Although the traditional post-tensioning prestressed construction technology is widely used in bridge construction, its construction process operation requires sufficient space. When the tensioning conditions are limited, the prestressed construction technology in a small space needs to be further studied and optimized. Therefore, a steel bundle bidirectional tensioning device is needed to ensure that the construction site is convenient while ensuring the quality of the completed bridge. Summary of the invention

[0004] The purpose of the present invention is to provide a device for bidirectional tensioning connection of prestressed steel strands in the mid-span of a prestressed box girder to solve the above-mentioned problem. The device can realize the tensioning of prestressed steel strands at the mid-span position inside the prestressed box girder and can play a role when there is no tensioning space at the beam end, the tensioning conditions are limited, and the construction period is tight.

[0005] To achieve the above object, the present invention provides the following solution: a device for bidirectional tensioning connection of prestressed steel strands in the mid-span of a prestressed box girder, comprising two prestressed steel strands arranged opposite to each other, and further comprising:

[0006] A bracket, arranged above the prestressed steel strand;

[0007] A connecting assembly, the connecting assembly comprising two fixed sleeves arranged opposite to each other on the bracket, the fixed sleeves being slidably connected to the bracket, a rotating pull rod being connected to the bottom end of the fixed sleeve, an opening and closing piece being arranged at the bottom end of the rotating pull rod, and the opening and closing piece having a clamping end and a clamping end;

[0008] A connecting anchor is arranged at the end of the prestressed steel bundle, and the connecting anchor is detachably connected to the rotating pull rod through the cooperation of the clamping end and the clamping end;

[0009] The tensioning member is arranged between the two rotating pull rods, and the two rotating pull rods rotate toward each other along the coaxial line through the tensioning member.

[0010] Preferably, the connecting anchor includes a threaded anchor fixed to the protruding end of the prestressed steel strand. An anchor ball hinge is fixed to the threaded anchor. Hemispherical hinge grooves are respectively formed on the mutually approaching sides of the clamping end and the holding end. The two hemispherical hinge grooves cooperate to form a ball hinge groove adapted to the anchor ball hinge. One end of the anchor ball hinge extends into the ball hinge groove and is detachably connected to the opening and closing member. An anchor connector is provided at the end of the threaded anchor away from the prestressed steel strand. The two ends of the anchor connector are respectively threadedly connected to the two threaded anchors.

[0011] Preferably, the opening and closing member is an alligator clip. The alligator clip has a fixed end and a movable end. The fixed end is fixed to the bottom end of the rotating pull rod. The movable end of the alligator clip is elastically connected to the fixed end. The hemispherical hinge groove is formed on the side where the movable end and the fixed end approach each other.

[0012] Preferably, the tensioning member includes a cable passing through between the two rotating pull rods. The two ends of the cable respectively penetrate through the two rotating pull rods and are slidably connected to the rotating pull rods. A fixed anchor is fixed to one end of the cable extending out of the rotating pull rod. A jack is provided on the cable. The two fixed anchors move towards each other along the same axis through the cable and the jack. A clamping member is provided between the fixed anchor and the rotating pull rod.

[0013] Preferably, the clamping member includes a spherical cushion block fixed to the cable. A spherical protrusion is fixed to the side of the rotating pull rod close to the spherical cushion block. Grooves are correspondingly formed on the spherical cushion block and the spherical protrusion. One end of the spherical protrusion extends into the groove and is clamped with the spherical cushion block.

[0014] Preferably, an adjusting assembly is provided on the bracket. The adjusting assembly includes two height-adjusting screws provided at the top end of the bracket. The height-adjusting screws penetrate through the bracket and are threadedly connected to the bracket. The height-adjusting screws can slide horizontally along the bracket. A fixed shaft sleeve is provided at the bottom end of the height-adjusting screws. The fixed shaft sleeve is rotatably fixed to the height-adjusting screws. A positioning member is also provided on the bracket. The two fixed shaft sleeves slide towards each other through the positioning member.

[0015] Preferably, the positioning member includes two distance-adjusting screws respectively provided on both sides of the bracket. One end of the distance-adjusting screws penetrates through the bracket and is threadedly connected to the bracket. The end of the distance-adjusting screw extending into the bracket abuts against the fixed shaft sleeve. A positioning balance rod is threadedly connected between the two fixed shaft sleeves.

[0016] Preferably, the bracket includes at least four columns. A number of the columns are evenly divided into two groups, and the two groups of columns respectively correspond to the two prestressed steel bundles one by one. A cross beam is fixedly connected between two adjacent columns on the same side. A tie beam is slidably connected between two oppositely arranged cross beams. The height-adjusting screw is arranged on the tie beam and is in threaded connection with the tie beam. A middle cross beam is also fixedly connected between two adjacent columns on the same side. A through groove is formed in the middle cross beam, and a threaded slider is slidably connected in the through groove. The distance-adjusting screw is arranged on the threaded slider and is in threaded connection with the threaded slider.

[0017] Preferably, universal wheels are arranged at the bottom ends of the columns.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] In the present invention, by erecting a bracket above the prestressed steel bundle, the bottom end of the rotating pull rod is made to correspond to the connecting anchor on the prestressed steel bundle by moving and adjusting the fixed bushing. First, the connecting anchor is clamped with the clamping end of the opening and closing member, and then the connecting anchor is fixed to the opening and closing member by using the clamping end, so as to realize the detachable connection between the connecting anchor and the rotating pull rod. Finally, the two rotating pull rods move towards each other through the tensioning member, and then the prestressed steel bundle is tensioned through the connecting anchor to realize two-way tensioning connection. Compared with the traditional post-tensioning prestressed construction process, in this patent, the tensioning member and the connecting component are supported by the bracket, reducing the space limitation of the tensioning device. Moreover, the prestressed steel bundle is quickly and detachably connected to the connecting component through the connecting anchor, facilitating the tensioning operation, improving the construction efficiency, and reducing the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings:

[0021] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a three-dimensional schematic diagram of the combination of the prestressed steel bundle and the rotating pull rod of the present invention;

[0023] Figure 3 It is a three-dimensional schematic diagram of the combination of the rotating pull rod and the fixed bushing of the present invention;

[0024] Figure 4 It is a three-dimensional schematic diagram of the fixing and position adjusting method of the fixed bushing of the present invention;

[0025] Figure 5 It is a three-dimensional schematic diagram of the support structure of the present invention;

[0026] Figure 6 It is a three-dimensional schematic diagram of the cable tensioning structure of the present invention;

[0027] Figure 7 It is a three-dimensional schematic diagram of the combination of the anchor and the spherical pad of the present invention;

[0028] Among them, 1. Prestressed steel strand; 2. Threaded anchor; 3. Anchor connector; 4. Anchor ball joint; 5. Rotating pull rod; 6. Fixed bushing; 7. Positioning balance rod; 8. Cable; 9. Limiting shaft bolt; 10. Limiting nut; 11. Height adjustment screw; 12. Distance adjustment screw; 13. Bracket; 13-1. Column; 13-2. Beam; 13-3. Connecting beam; 13-4. Middle beam; 13-5. Threaded slider; 14. Jack; 15. Alligator clip; 16. Spherical pad; 17. Anchor; 18. Universal wheel. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example:

[0032] Reference Figure 1-7 The present invention provides a device for bidirectional tensioning connection of prestressed steel strands in the mid-span of a prestressed box girder, comprising two prestressed steel strands 1 arranged opposite to each other, and further comprising:

[0033] A bracket 13 is arranged above the prestressed steel strand 1;

[0034] The connecting assembly includes two fixed sleeves 6 arranged on the bracket 13, the fixed sleeves 6 are slidably connected to the bracket 13, the bottom end of the fixed sleeves 6 is connected to the rotating rod 5, the bottom end of the rotating rod 5 is provided with an opening and closing piece, and the opening and closing piece has a clamping end and a clamping end;

[0035] A connecting anchor is arranged at the end of the prestressed steel strand 1, and the connecting anchor is detachably connected to the rotating pull rod 5 through the cooperation of the clamping end and the clamping end;

[0036] The tensioning member is arranged between the two rotating tie rods 5, and the two rotating tie rods 5 rotate towards each other along the same axis through the tensioning member.

[0037] In the present invention, a support 13 is erected above the prestressed steel strand 1. By moving and adjusting the fixed shaft sleeve 6, the bottom end of the rotating tie rod 5 is made to correspond to the connecting anchor on the prestressed steel strand 1. First, the connecting anchor is clamped with the clamping end of the opening and closing member, and then the connecting anchor is fixed to the opening and closing member by the clamping end, realizing the detachable connection between the connecting anchor and the rotating tie rod 5. Finally, the two rotating tie rods 5 are moved towards each other through the tensioning member, and then the prestressed steel strand 1 is tensioned through the connecting anchor to achieve two-way tensioning connection. Compared with the traditional post-tensioning prestressed construction process, in this patent, the tensioning member and the connecting component are supported by the support 13, reducing the space limitation of the tensioning device. Moreover, the prestressed steel strand 1 is quickly and detachably connected to the connecting component through the connecting anchor, facilitating the tensioning operation, improving the construction efficiency, and reducing the construction period.

[0038] In an embodiment of the present invention, preferably but not limited to, a limiting rotating shaft bolt 9 is inserted through the connecting end of the rotating tie rod 5 and the fixed shaft sleeve 6, and a limiting nut 10 is threadedly connected to one end of the limiting rotating shaft bolt 9 passing through the fixed shaft sleeve 6. The rotating connection between the rotating tie rod 5 and the fixed shaft sleeve 6 is realized through the limiting rotating shaft bolt 9 and the limiting nut 10.

[0039] Furthermore, the connecting anchor includes a threaded anchor 2 fixedly connected to the extending end of the prestressed steel strand 1. An anchor ball hinge 4 is fixedly connected to the threaded anchor 2. Hemispherical hinge grooves are respectively formed on the mutually approaching sides of the clamping end and the holding end. The two hemispherical hinge grooves cooperate to form a ball hinge groove adapted to the anchor ball hinge 4. One end of the anchor ball hinge 4 extends into the ball hinge groove to be detachably connected to the opening and closing member. An anchor connector 3 is arranged at the end of the threaded anchor 2 away from the prestressed steel strand 1, and both ends of the anchor connector 3 are threadedly connected to the two threaded anchors 2.

[0040] Refer to Figure 1 、 6 The prestressed steel strand 1 to be tensioned is fixedly connected through the threaded anchor 2, and the threaded anchor 2 is combined with the anchor ball hinge 4. The anchor ball hinge 4 is then connected and fixed by the opening and closing member at the bottom end of the rotating tie rod 5. By adopting the anchor ball hinge 4, the effect of keeping the prestressed steel strand 1 always horizontal during the rotation of the rotating tie rod 5 can be achieved. And before the tensioning starts, the anchor connector 3 is threadedly connected to one threaded anchor 2. By continuously moving the two prestressed steel strands 1 towards each other through the tensioning member, after the tensioning is completed, the anchor connector 3 is threadedly connected and fixed to the anchor heads of the two threaded anchors 2 to complete the construction of the overall two-way tensioning prestress.

[0041] Furthermore, the opening and closing member is an alligator clip 15, which has a fixed end and a movable end. The fixed end is fixedly connected to the bottom end of the rotating pull rod 5, the movable end of the alligator clip 15 is elastically connected to the fixed end, and the hemispherical hinge groove is opened on the side where the movable end and the fixed end are close to each other.

[0042] Reference Figure 2 A hemispherical hinge groove is provided on the sides close to each other of the movable end and the fixed end of the crocodile clip 15. When the prestressed steel bundle 1 is connected to the rotating pull rod 5, the anchor ball hinge 4 is first extended into the hemispherical hinge groove of the fixed end for clamping and fixing. The hemispherical hinge groove is the clamping end, and then the movable end of the crocodile clip 15 is buckled and fixed to form a clamping end, thereby realizing the rapid fixation of the prestressed steel bundle 1 and the rotating pull rod 5.

[0043] Furthermore, the tensioning member includes a cable 8 passed through the two rotating rods 5, both ends of the cable 8 respectively pass through the two rotating rods 5 and are slidably connected with the rotating rods 5, and a fixed anchor 17 is fixedly connected to one end of the cable 8 extending out of the rotating rod 5, a jack 14 is provided on the cable 8, and the two fixed anchors 17 move toward each other along the same axis through the cable 8 and the jack 14, and a clamping member is provided between the fixed anchor 17 and the rotating rod 5.

[0044] Furthermore, the clamping part includes a spherical pad 16 fixedly connected to the cable 8, and a spherical protrusion is fixedly connected to the side of the rotating pull rod 5 close to the spherical pad 16. The spherical pad 16 and the spherical protrusion are correspondingly provided with grooves, and one end of the spherical protrusion extends into the groove and is clamped with the spherical pad 16.

[0045] Reference Figure 2 , 6 7. Fix the fixed anchor 17 and the spherical pad 16 to the end of the cable 8 extending out of the rotating rod 5, install the jack 14 at one end of the cable 8, and shrink the cable 8 by the jack 14 so that the fixed anchor 17 squeezes the spherical pad 16, and the spherical pad 16 fits with the spherical protrusion, thereby making the rotating rod 5 rotate around the fixed shaft sleeve 6, and the cable 8 can always be kept in a horizontal state during the rotation process, so that the force on the cable 8 is kept stable.

[0046] Furthermore, an adjustment component is provided on the bracket 13, and the adjustment component includes two height adjustment screws 11 arranged at the top of the bracket 13. The height adjustment screws 11 pass through the bracket 13 and are threadedly connected to the bracket 13, and the height adjustment screws 11 can slide horizontally along the bracket 13. A fixed sleeve 6 is provided at the bottom end of the height adjustment screw 11, and the fixed sleeve 6 is rotatably fixed to the height adjustment screw 11. A positioning piece is also provided on the bracket 13, and the two fixed sleeves 6 slide toward each other through the positioning piece.

[0047] Further, the positioning member includes two distance-adjusting screws 12 respectively arranged on both sides of the bracket 13. One end of each distance-adjusting screw 12 penetrates through the bracket 13 and is threadedly connected to the bracket 13. The end of the distance-adjusting screw 12 extending into the bracket 13 abuts against the fixed bushing 6. A positioning balance rod 7 is threadedly connected between the two fixed bushings 6.

[0048] Refer to Figure 1 , 4 After the bracket 13 is placed above the prestressed steel strand 1, by turning and horizontally sliding the height-adjusting screw 11 simultaneously, not only can a good force transmission path be formed with the bracket 13, but also the vertical position of the fixed bushing 6 can be finely adjusted. Furthermore, the rotating tie rod 5 connected to the bottom end of the fixed bushing 6 can be correspondingly moved to the connection anchor of the prestressed steel strand 1 to be tensioned. Then, the distance-adjusting screws 12 on both sides of the bracket 13 are rotated to adjust the distance between the two fixed bushings 6. The elongation of the prestressed steel strand 1 is controlled by controlling the distance between the two fixed bushings 6. After the position of the fixed bushing 6 is positioned, the positioning balance rod 7 is rotated to connect the left and right fixed bushings 6, which plays a role in ensuring that the distance between the two fixed bushings 6 remains consistent during the tensioning process of the prestressed steel strand 1.

[0049] Further, the bracket 13 includes at least four columns 13-1. The several columns 13-1 are evenly divided into two groups, and the two groups of columns 13-1 respectively correspond to the two prestressed steel strands 1 one by one. A cross beam 13-2 is fixedly connected between two adjacent columns 13-1 on the same side. A connecting beam 13-3 is slidably connected between the two oppositely arranged cross beams 13-2. The height-adjusting screw 11 is arranged on the connecting beam 13-3 and is threadedly connected to the connecting beam 13-3. A middle cross beam 13-4 is also fixedly connected between two adjacent columns 13-1 on the same side. A through groove is formed in the middle cross beam 13-4, and a threaded slider 13-5 is slidably connected in the through groove. The distance-adjusting screw 12 is arranged on the threaded slider 13-5 and is threadedly connected to the threaded slider 13-5.

[0050] Refer to Figure 5 , on the mutually approaching sides of the two oppositely arranged cross beams 13-2, a chute is formed. The two ends of the connecting beam 13-3 extend into the chute and are slidably connected to the cross beam 13-2. Cooperating with the threaded connection between the height-adjusting screw 11 and the connecting beam 13-3, the vertical and horizontal position adjustments of the fixed bushing 6 are realized. At the same time, the distance-adjusting screw 12 slides in the middle cross beam 13-4 through the threaded slider 13-5, which is convenient for flexibly adjusting the distance between the fixed bushings 6.

[0051] And it can be imagined that another through groove is formed in the connecting beam 13-3, and another threaded slider (not shown in the figure) is slidably connected in the through groove, so that the height-adjusting screw 11 is threadedly connected to the threaded slider, realizing the multi-axial sliding of the height-adjusting screw 11 along the horizontal direction.

[0052] Furthermore, a universal wheel 18 is provided at the bottom end of the upright column 13-1.

[0053] The working process of this embodiment is as follows:

[0054] Supports 13 are respectively lapped above the prestressed steel strands 1 on both sides. The prestressed steel strands 1 are connected to the rotating tie rod 5 through threaded anchors 2, anchor ball hinges 4, and alligator clips 15; the rotating tie rod 5 is combined with the fixed bushing 6 through a limit rotating shaft bolt 9 and a limit nut 10; the fixed bushing 6 is combined with the support 13 through upper and lower height-adjusting screws 11. After adjusting the rotating tie rod 5 to the position connected to the prestressed steel strand 1, the distance between the two fixed bushings 6 is adjusted by rotating the distance-adjusting screws 12 on both sides of the support 13. After the positions of the fixed bushings 6 are positioned, the positioning balance rod 7 is rotated to connect the left and right fixed bushings 6. The tension of the jack 14 is transmitted by the cable 8 to drive the rotating tie rod 5 to rotate, so that the threaded anchor 2 is pulled together, and the left and right threaded anchors 2 are combined through the anchor connector 3 to realize the tensioning of the prestressed steel strand 1.

[0055] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0056] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A device for bidirectional tension connection of prestressed steel tendons at the mid-span of a prestressed box girder, comprising two prestressed steel tendons (1) arranged oppositely, characterized in that: Also includes, A bracket (13) is arranged above the prestressed steel bundle (1); A connecting assembly, the connecting assembly comprising two fixed sleeves (6) arranged opposite to each other on the bracket (13), the fixed sleeves (6) being slidably connected to the bracket (13), the bottom end of the fixed sleeves (6) being connected to a rotating pull rod (5), the bottom end of the rotating pull rod (5) being provided with an opening and closing piece, the opening and closing piece having a clamping end and a clamping end; A connecting anchor is arranged at the end of the prestressed steel bundle (1), and the connecting anchor is detachably connected to the rotating pull rod (5) through the cooperation of the clamping end and the clamping end; A tensioning member, the tensioning member being arranged between the two rotating pull rods (5), and the two rotating pull rods (5) being rotated toward each other along a coaxial line through the tensioning member; The tensioning member comprises a cable (8) passing through the two rotating rods (5), the two ends of the cable (8) respectively passing through the two rotating rods (5) and slidingly connected with the rotating rods (5), and a fixed anchor (17) is fixedly connected to one end of the cable (8) extending out of the rotating rod (5), a jack (14) is arranged on the cable (8), and the two fixed anchors (17) move toward each other along the same axis through the cable (8) and the jack (14).

2. The device for bidirectional tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 1, wherein: The connecting anchor comprises a threaded anchor (2) fixedly connected to the protruding end of the prestressed steel bundle (1), an anchor ball joint (4) fixedly connected to the threaded anchor (2), and semi-spherical joint grooves are respectively provided on the mutually close sides of the clamping end and the clamping end, and the two semi-spherical joint grooves cooperate to form a ball joint groove adapted to the anchor ball joint (4), one end of the anchor ball joint (4) extends into the ball joint groove and is detachably connected to the opening and closing part, and an anchor connector (3) is provided at the end of the threaded anchor (2) away from the prestressed steel bundle (1), and the two ends of the anchor connector (3) are respectively threadedly connected to the two threaded anchors (2).

3. The device for two-way tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 2, characterized in that: The opening and closing member is an alligator clip (15), which has a fixed end and a movable end. The fixed end is fixedly connected to the bottom end of the rotating pull rod (5), the movable end of the alligator clip (15) is elastically connected to the fixed end, and the hemispherical hinge groove is arranged on the side where the movable end and the fixed end are close to each other.

4. The device for bidirectional tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 1, characterized in that: A clamping piece is provided between the fixing anchor (17) and the rotating pull rod (5).

5. The device for bidirectional tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 4, wherein: The clamping part comprises a spherical pad (16) fixedly connected to the cable (8); a spherical protrusion is fixedly connected to one side of the rotating pull rod (5) close to the spherical pad (16); the spherical pad (16) and the spherical protrusion are provided with grooves corresponding to the spherical pad; one end of the spherical protrusion extends into the groove to be clamped with the spherical pad (16).

6. The device for two-way tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 1, wherein: An adjusting assembly is provided on the bracket (13). The adjusting assembly includes two height-adjusting screws (11) provided at the top of the bracket (13). The height-adjusting screws (11) penetrate through the bracket (13) and are threadedly connected to the bracket (13), and the height-adjusting screws (11) can slide horizontally along the bracket (13). A fixed bushing (6) is provided at the bottom end of the height-adjusting screw (11). The fixed bushing (6) is rotatably fixed to the height-adjusting screw (11). A positioning member is also provided on the bracket (13). The two fixed bushings (6) slide towards each other through the positioning member.

7. The device for two-way tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 6, wherein: The positioning member includes two distance-adjusting screws (12) respectively provided on both sides of the bracket (13). One end of the distance-adjusting screw (12) penetrates through the bracket (13) and is threadedly connected to the bracket (13). The end of the distance-adjusting screw (12) extending into the bracket (13) abuts against the fixed bushing (6). A positioning balance rod (7) is threadedly connected between the two fixed bushings (6).

8. The device for bidirectional tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 7, characterized in that: The bracket (13) includes at least four columns (13-1). The several columns (13-1) are evenly divided into two groups, and the two groups of columns (13-1) respectively correspond to the two prestressed steel bundles (1). A cross beam (13-2) is fixedly connected between two adjacent columns (13-1) on the same side. A connecting beam (13-3) is slidably connected between the two oppositely arranged cross beams (13-2). The height-adjusting screw (11) is inserted into the connecting beam (13-3) and is threadedly connected to the connecting beam (13-3). A middle cross beam (13-4) is also fixedly connected between two adjacent columns (13-1) on the same side. A through groove is formed in the middle cross beam (13-4). A threaded slider (13-5) is slidably connected in the through groove. The distance-adjusting screw (12) is inserted into the threaded slider (13-5) and is threadedly connected to the threaded slider (13-5).

9. The device for two-way tension connection of prestressed steel tendons at the mid-span of a prestressed box girder according to claim 8, characterized in that: A universal wheel (18) is provided at the bottom end of the column (13-1).

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