Prestressed tensioning device in concrete bridge and use method thereof

Abstract

The application relates to the field of prestress tension devices, in particular to a prestress tension device in a concrete bridge, which comprises a main support plate, the right side of the main support plate is fixedly connected with symmetrical base plates, a slave support plate is fixedly connected between the two base plates, the right side of the slave support plate is fixedly connected with symmetrical hydraulic cylinders, and a tension plate is fixedly connected between the two hydraulic cylinders. The prestress tension device in the concrete bridge and the using method are composed of an eliminating mechanism and a replacing mechanism; when the steel strand body is fractured in the tension process, the fractured steel strand body cannot limit the rotation of the eliminating ring any more, at the moment, the reset coil spring rotates with the end face tooth ring, the eliminating ring rotates eccentrically with the fractured steel strand body under the cooperation of the ratchet block and the ratchet, the stress of the steel strand body after the fracture is offset through the force of the eccentric rotation of the steel strand, and the fractured steel strand body is prevented from rebounding too much to hurt the operating personnel.

Description

Technical Field

[0001] This invention relates to the field of prestressed tensioning devices, specifically a prestressed tensioning device for concrete bridges and its usage method. Background Technology

[0002] In bridge construction, prestress needs to be applied to the inside of the concrete slab to prevent cracking during later use. During construction, one end of the steel strand is first fixed, and then the other end of the steel strand is stretched by the tensioning equipment. After the concrete is poured, the tension is released.

[0003] An existing patent (publication number: CN110904848A) discloses a prestressed tensioning device for steel strands used in bridge construction, including a base with three linearly distributed lower slots on the upper surface of the base, and a top plate installed parallel to the upper end of the base. During the development of this solution, the inventors discovered the following unresolved issues in the existing technology: 1. During use, when the steel strand breaks on the left side of the device, the warning device and pressure plate on the right side can only press the right end of the steel strand. However, the steel strand may bounce and cause injury due to internal prestress during breakage, making it difficult to eliminate the stress caused by the bounce. 2. During use, if the hydraulic equipment cannot be stopped promptly when one steel strand breaks, uneven stress on the remaining steel strands during tensioning can easily lead to the simultaneous breakage of multiple steel strands. Summary of the Invention

[0004] The purpose of this invention is to provide a prestressing tensioning device and its usage method for concrete bridges, in order to solve the problems mentioned in the background art: 1. Existing prestressing tensioning equipment has difficulty eliminating the stress generated after the steel strand breaks during use; 2. In the use of existing prestressing tensioning equipment, when one steel strand breaks, the other steel strands are prone to uneven stress. To achieve the above objectives, this invention provides the following technical solution: A prestressing tensioning device for concrete bridges, comprising a main support plate, pads symmetrically fixedly connected to the right side of the main support plate, a secondary support plate fixedly connected between the two pads, hydraulic cylinders symmetrically fixedly connected to the right side of the secondary support plate, and a tensioning plate fixedly connected between the two hydraulic cylinders;

[0005] Three steel strand bodies are equidistantly installed in the middle of the main support plate, and the three steel strand bodies pass through the support plate and are installed on the surface of the tensioning plate.

[0006] An elimination mechanism is movably connected between the support plate and the steel strand body, and a replacement mechanism is movably connected between the tension plate and the support plate. The surface of the replacement mechanism overlaps with the surface of the steel strand body.

[0007] Preferably, the elimination mechanism includes a movable groove, which is opened on the left side of the support plate. An end face toothed ring is rotatably connected inside the movable groove. An elimination ring is provided on the inner ring of the end face toothed ring. A support bearing is fixedly connected between the right side of the elimination ring and the inner wall of the movable groove. A return coil spring is fixedly connected between the right side of the end face toothed ring and the inner wall of the movable groove.

[0008] The inner ring of the end face toothed ring is provided with eight adjusting grooves at equal intervals along the circumference. A pawl block is slidably connected inside the adjusting groove. A compression spring is fixedly connected between one end of the pawl block and the inner wall of the adjusting groove. The outer ring of the elimination ring is fixedly connected with a ratchet tooth that cooperates with the pawl block. The center of the elimination ring is eccentrically provided with a through hole that cooperates with the steel strand body.

[0009] Both sides of the movable groove are provided with transmission grooves. A spool rod is rotatably connected to the inner wall of the transmission groove. One end of the spool rod extends into the movable groove and is fixedly sleeved with a one-way bearing. A spur gear is fixedly sleeved on the outer ring of the one-way bearing. The side wall of the spur gear meshes with the side wall of the end face gear ring.

[0010] A pull rope is provided in the middle of the reel rod, and a conical clamp is fixedly installed in the middle of the steel strand body. Both ends of the conical clamp are fixedly connected to pull rods, and the two pull rods are respectively fixedly connected to one end of the two pull ropes.

[0011] Preferably, a sealed bearing is fixedly connected to the inner wall of the movable groove, and the outer ring of the end face toothed ring is fixedly connected to the inner ring of the sealed bearing;

[0012] The inner wall of the movable groove is provided with a circular hole that matches the through hole.

[0013] Preferably, a restoring coil spring is fixedly connected between the side wall of the pulley rod and the inner wall of the transmission groove, and the ropes on the surfaces of the two pulley rods are wound in opposite directions.

[0014] Preferably, the replacement mechanism includes three replacement cone holes, which are equidistantly located at the bottom of the tensioning plate. Each of the three replacement cone holes corresponds to one of the three steel strand bodies. An elastic clamp is movably inserted into the interior of each replacement cone hole, and a replacement steel wire is movably inserted between the elastic clamp and the inner wall of the replacement cone hole. The left end of the replacement steel wire is fixedly connected to the side wall of the support plate.

[0015] A pad that matches the replacement cone hole is fixedly connected to the upper left side of the tensioning plate. A spring telescopic rod is fixedly connected to the bottom of the pad. An arc-shaped pressure plate is fixedly connected to the bottom of the spring telescopic rod. The middle part of the arc-shaped pressure plate overlaps with the surface of the steel strand body. Pressure rods are fixedly connected to both sides of the arc-shaped pressure plate.

[0016] Both sides of the elastic clamp are fixedly connected to trapezoidal pressure blocks, and the two trapezoidal pressure blocks correspond one-to-one with the two pressure rods. A return spring is fixedly connected between the side wall of the elastic clamp and the side wall of the tensioning plate.

[0017] Preferably, a conical limiting block is fixedly connected to the middle of the pressure rod, and a limiting spring rod that cooperates with the conical limiting block is symmetrically fixedly connected to the side wall of the tensioning plate.

[0018] Preferably, connecting blocks are fixedly connected to both sides of the elastic clamp, the reset spring is fixedly connected between the side wall of the connecting block and the side wall of the tensioning plate, and the elastic clamp is tapered.

[0019] A method for using a prestressed tensioning device in a concrete bridge includes the following steps:

[0020] S1. When using this prestressed tensioning device, firstly, one end of the steel strand body is installed on the main support plate. Then, the other end of the steel strand body passes through the hole in the middle of the elimination ring, the conical clamp, and is fixedly installed on the side wall of the tensioning plate from the back of the support plate. Next, the conical clamp is fixed on the surface of the steel strand body, and at the same time, the arc-shaped pressure plate on the tensioning plate overlaps on the surface of the steel strand body.

[0021] S2. Then, the hydraulic cylinder is activated to extend and move the tensioning plate to synchronously tension the three steel strand bodies on the tensioning plate. As the steel strand bodies are stretched, the conical clamps move synchronously, causing the conical clamps to rotate through the pull rope and the wire wheel rod. At this time, the wire wheel rod rotates synchronously through the one-way bearing and the sprocket, so that the sprocket meshes with the side wall of the end face toothed ring. During the counterclockwise rotation of the end face toothed ring, when the inclined surface of the pawl block movable in the inner ring of the end face toothed ring presses against the inclined surface of the ratchet, the pawl block slides into the adjustment groove, so that the end face toothed ring does not rotate synchronously with the elimination ring when it rotates counterclockwise. The counterclockwise rotating end face toothed ring rotates with the return coil spring to store force, and the tensioned steel strand bodies can limit the rotation of the elimination ring.

[0022] S3. When any strand body breaks during tensioning at the left side, the strand no longer restricts the release ring. At the same time, the stored reset spring recovers and rotates clockwise with the end face toothed ring. Due to the one-way bearing, the spur gear will not rotate the pulley rod during reverse rotation. The pawl block of the inner ring of the end face toothed ring presses against the plane of the ratchet and rotates clockwise with the release ring. At this time, the release ring rotates eccentrically with the broken strand body through the perforation. The force of this eccentric rotation counteracts the stress of the strand body after breakage and reduces the amplitude of the strand body after breakage.

[0023] S4. When one of the steel strands breaks, the steel strand is no longer under tension. At this time, the spring telescopic rod elastically recovers and moves the arc-shaped pressure plate down on the surface of the tensioning plate, so that the pressure rod presses against the inclined surface of the trapezoidal pressure block, and the trapezoidal pressure block moves into the replacement cone hole with the elastic clamp. At this time, the outer ring of the elastic clamp is pressed by the inner wall of the replacement cone hole, so that the elastic clamp closes and clamps the replacement steel wire. The replacement steel wire replaces the broken steel strand, so that the tension force is evenly distributed.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] In this invention, by using components such as the elimination ring, end face toothed ring, and return coil spring in combination, when the steel strand body breaks during tensioning, the broken steel strand body can no longer restrict the rotation of the elimination ring. At this time, the return coil spring rotates with the end face toothed ring, and under the cooperation of the pawl block and the ratchet, the elimination ring carries the broken steel strand body to rotate eccentrically. The force of the eccentric rotation of the steel strand counteracts the stress of the steel strand body after it breaks, thus avoiding excessive bounce of the steel strand body after it breaks, which could injure the workers.

[0026] In this invention, through the coordinated use of components such as the spring telescopic rod, the replacement cone hole, and the elastic clamp, when the steel strand body breaks, it is no longer in a taut state. At this time, the spring telescopic rod moves down with the arc-shaped pressure plate, causing the pressure rod to press against the side wall of the trapezoidal pressure block. Then, the trapezoidal pressure block moves into the interior of the replacement cone hole with the elastic clamp, causing the elastic clamp to deform and clamp the replacement steel wire, thus replacing the broken steel strand body. This avoids the risk of other steel strand bodies breaking due to uneven tension distribution caused by the operator not stopping the hydraulic cylinder in time after the steel strand body breaks.

[0027] In this invention, by using components such as tensioning plate, elimination mechanism and replacement mechanism in combination, the tensioning plate can reduce the bounce amplitude of any broken steel strand body during the tensioning process of multiple steel strand bodies, and can evenly distribute the tension force after the steel strand bodies break at different positions, thereby improving the stability of the tensioning device. Attached Figure Description

[0028] Figure 1 This is a top sectional view of the present invention from the position of the support plate;

[0029] Figure 2 For the present invention Figure 1 Enlarged view of the structure at point A in the middle;

[0030] Figure 3 This is a top sectional view of a portion of the movable groove and transmission groove of the present invention;

[0031] Figure 4This is a left cross-sectional view of a portion of the end face toothed ring and the elimination ring of the present invention;

[0032] Figure 5 This is a right sectional view of a portion of the end face toothed ring and the elimination ring of the present invention;

[0033] Figure 6 This is a cross-sectional view of a portion of the tensioning plate and replacement steel wire of the present invention;

[0034] Figure 7 For the present invention Figure 6 Enlarged view of the structure at point B;

[0035] Figure 8 This is a left cross-sectional view of a portion of the tensioning plate and elastic clamp of the present invention.

[0036] In the diagram: 1. Main support plate; 2. Pad plate; 3. Secondary support plate; 4. Hydraulic cylinder; 5. Tensioning plate; 6. Steel strand body; 7. Elimination mechanism; 701. Movable groove; 702. End face toothed ring; 703. Elimination ring; 704. Support bearing; 705. Return spring; 706. Adjustment groove; 707. Pawl block; 708. Compression spring; 709. Racket; 710. Through hole; 711. Transmission groove; 712. Wire wheel rod; 713. One-way bearing; 714. Circular gear; 715. Pull rod; 716. Pull rope; 717. Conical clamp; 8. Replacement mechanism; 801. Replacement conical hole; 802. Elastic clamp; 803. Replacement steel wire; 804. Pad block; 805. Spring telescopic rod; 806. Arc-shaped pressure plate; 807. Pressure rod; 808. Trapezoidal pressure block; 809. Return spring. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figures 1 to 8 This invention provides a technical solution: a prestressed tensioning device for concrete bridges, comprising a main support plate 1, pads 2 symmetrically fixedly connected to the right side of the main support plate 1, a secondary support plate 3 fixedly connected between the two pads 2, hydraulic cylinders 4 symmetrically fixedly connected to the right side of the secondary support plate 3, and a tensioning plate 5 fixedly connected between the two hydraulic cylinders 4. It should be noted that this device is suitable for prestressed construction using the pre-tensioning method, where the steel strand body 6 is tensioned first, and then formwork is supported between the main support plate 1 and the secondary support plate 3 before concrete is poured.

[0039] Three steel strand bodies 6 are equidistantly installed in the middle of the main support plate 1. The three steel strand bodies pass through the support plate 3 and are installed on the surface of the tensioning plate 5. It should be noted that tensioning anchors are fixedly installed at both ends of the steel strands to the corresponding main support plate 1 and tensioning plate 5. The tensioning anchors are fixed by bolts. The tensioning anchors and their installation are existing technologies and will not be described in detail.

[0040] An elimination mechanism 7 is movably connected between the support plate 3 and the steel strand body 6, and a replacement mechanism 8 is movably connected between the tension plate 5 and the support plate 3. The surface of the replacement mechanism 8 overlaps with the surface of the steel strand body 6.

[0041] In this embodiment, as Figures 1 to 8 As shown, the elimination mechanism 7 includes a movable groove 701, which is opened on the left side of the support plate 3. An end face toothed ring 702 is rotatably connected inside the movable groove 701. An elimination ring 703 is provided on the inner ring of the end face toothed ring 702. A support bearing 704 is fixedly connected between the right side of the elimination ring 703 and the inner wall of the movable groove 701. A reset coil spring 705 is fixedly connected between the right side of the end face toothed ring 702 and the inner wall of the movable groove 701.

[0042] The inner ring of the end face toothed ring 702 has eight adjusting grooves 706 evenly spaced around its circumference. A pawl block 707 is slidably connected inside each adjusting groove 706. A compression spring 708 is fixedly connected between one end of the pawl block 707 and the inner wall of the adjusting groove 706. The outer ring of the elimination ring 703 is fixedly connected with ratchet teeth 709 that mate with the pawl block 707. A through hole 710, eccentrically located in the center of the elimination ring 703, mates with the steel strand body 6. It should be noted that there are twenty-four ratchet teeth 709, evenly spaced around the circumference of the elimination ring 703. One side of the ratchet teeth 709 and the pawl block 707 is an inclined surface, and the other side is a flat surface, so that when the end face toothed ring 702 rotates counterclockwise, it will not cause the ratchet teeth 709 and the elimination ring 703 to rotate via the pawl block 707. When the end face toothed ring 702 rotates clockwise, it can cause the elimination ring 703 to rotate.

[0043] Both sides of the movable groove 701 are provided with transmission grooves 711. A sheave rod 712 is rotatably connected to the inner wall of the transmission groove 711. One end of the sheave rod 712 extends into the movable groove 701 and is fixedly sleeved with a one-way bearing 713. A spur gear 714 is fixedly sleeved on the outer ring of the one-way bearing 713. The side wall of the spur gear 714 meshes with the side wall of the end face gear ring 702. It should be noted that the one-way bearing 713 enables the sheave rod 712 to rotate with the spur gear 714, while the spur gear 714 cannot rotate with the sheave rod 712.

[0044] A pull rope 716 is provided in the middle of the reel rod 712, and a conical clamp 717 is fixedly installed in the middle of the steel strand body 6. Both ends of the conical clamp 717 are fixedly connected to pull rods 715, and each pull rod 715 is fixedly connected to one end of a pull rope 716. It should be noted that because the steel strand body 6 is eccentrically positioned relative to the movable groove 701, the two pull rods 715 have the same structure but different lengths. The conical clamp 717 is fixedly installed on the steel strand body 6 by bolts, and moves synchronously with the stretching of the steel strand body 6.

[0045] In this embodiment, as Figures 1 to 8 As shown, a sealed bearing is fixedly connected to the inner wall of the movable groove 701, and the outer ring of the end face toothed ring 702 is fixedly connected to the inner ring of the sealed bearing.

[0046] The inner wall of the movable groove 701 has a circular hole that matches the through hole 710. It should be noted that the steel strand body 6 is inserted into the through hole 710 in the middle of the elimination ring 703 and the circular hole on the support plate 3.

[0047] In this embodiment, as Figures 1 to 8 As shown, a restoring coil spring is fixedly connected between the side wall of the pulley rod 712 and the inner wall of the transmission groove 711. The pull ropes 716 on the surfaces of the two pulley rods 712 are wound in opposite directions. It should be noted that by setting the two pull ropes 716 in opposite winding directions, when the conical clamp 717 moves with the two pull ropes 716, the rotation directions of the two pulley rods 712 are opposite. At this time, the rotation directions of the two spur gears 714 are opposite, so that when the two spur gears 714 mesh with the two sides of the end face gear ring 702 respectively, there will be no interference, ensuring the stable rotation of the end face gear ring 702.

[0048] In this embodiment, as Figures 1 to 8 As shown, the replacement mechanism 8 includes three replacement cone holes 801. The three replacement cone holes 801 are equidistantly opened at the lower part of the tensioning plate 5. The three replacement cone holes 801 correspond one-to-one with the three steel strand bodies 6. An elastic clamp 802 is movably inserted into the interior of the replacement cone hole 801. A replacement steel wire 803 is movably inserted between the elastic clamp 802 and the inner wall of the replacement cone hole 801. The left end of the replacement steel wire 803 is fixedly connected to the side wall of the support plate 3.

[0049] A pad 804, which mates with the replacement cone hole 801, is fixedly connected to the upper left side of the tensioning plate 5. A spring telescopic rod 805 is fixedly connected to the bottom of the pad 804, and an arc-shaped pressure plate 806 is fixedly connected to the bottom of the spring telescopic rod 805. The middle part of the arc-shaped pressure plate 806 overlaps with the surface of the steel strand body 6, and pressure rods 807 are fixedly connected to both sides of the arc-shaped pressure plate 806. It should be noted that a ball bearing is rotatably connected to the middle of the arc-shaped pressure plate 806, and the surface of the ball bearing overlaps with the surface of the steel strand body 6. The ball bearing is designed to reduce the frictional resistance between the steel strand body 6 and the arc-shaped pressure plate 806 during the tensioning process. When the steel strand body 6 breaks, the elasticity of the spring telescopic rod 805 can resist the deformation of the broken steel strand body 6.

[0050] Both sides of the elastic clamp 802 are fixedly connected with trapezoidal pressure blocks 808, and the two trapezoidal pressure blocks 808 correspond one-to-one with the two pressure rods 807. A return spring 809 is fixedly connected between the side wall of the elastic clamp 802 and the side wall of the tensioning plate 5.

[0051] In this embodiment, as Figures 1 to 8 As shown, a conical limiting block is fixedly connected to the middle of the pressure rod 807, and limiting spring rods that cooperate with the conical limiting block are symmetrically fixedly connected to the side wall of the tensioning plate 5. It should be noted that when the pressure rod 807 moves down a certain distance with the arc-shaped pressure plate 806, the limiting spring rods can limit the conical limiting block and the pressure rod 807, so that the trapezoidal pressure plate 808 with the elastic clamp 802 can be stably inserted into the replacement conical hole 801, ensuring the stability of the elastic clamp 802 in holding the replacement steel wire 803.

[0052] In this embodiment, as Figures 1 to 8 As shown, connecting blocks are fixedly connected to both sides of the elastic clamp 802, and a return spring 809 is fixedly connected between the side wall of the connecting block and the side wall of the tensioning plate 5. The elastic clamp 802 is tapered. It should be noted that: due to the tapered design, when the elastic clamp 802 moves into the replacement tapered hole 801, the outer ring of the elastic clamp 802 is compressed and deformed, which can clamp the replacement steel wire 803.

[0053] In this embodiment, as Figures 1 to 8 As shown, a method for using a prestressed tensioning device in a concrete bridge includes the following steps:

[0054] S1. When using this prestressed tensioning device, firstly, one end of the steel strand body 6 is installed on the main support plate 1. Then, the other end of the steel strand body 6 passes through the perforation 710 in the middle of the elimination ring 703 and the conical clamp 717 in sequence, and is fixedly installed on the side wall of the tensioning plate 5 from the back of the support plate 3. Then, the conical clamp 717 is fixed on the surface of the steel strand body 6, and at the same time, the arc-shaped pressure plate 806 on the tensioning plate 5 overlaps the surface of the steel strand body 6.

[0055] S2. Then, the hydraulic cylinder 4 is activated to extend and move the tensioning plate 5 to synchronously tension the three steel strand bodies 6 on the tensioning plate 5. As the steel strand bodies 6 are stretched, they will move synchronously with the conical clamp 717, causing the conical clamp 717 to rotate through the pull rope 716 and the sheave rod 712. At this time, the sheave rod 712 drives the sprocket 714 to rotate synchronously through the one-way bearing 713, so that the sprocket 714 meshes with the side wall of the end face gear ring 702 for transmission. During the counterclockwise rotation of 702, when the inclined surface of the pawl block 707, which is movably set on the inner ring of the end face toothed ring 702, presses against the inclined surface of the ratchet 709, the pawl block 707 slides into the adjusting groove 706, so that the end face toothed ring 702 will not rotate synchronously with the elimination ring 703 when it rotates counterclockwise, and the counterclockwise rotating end face toothed ring 702 carries the reset coil spring 705 to rotate and store force, while the tensioned steel strand body 6 can limit the rotation of the elimination ring 703;

[0056] S3. When any strand body 6 breaks during tensioning at the left side, the strand no longer restricts the release ring 703. At the same time, the stored return spring 705 recovers and rotates clockwise with the end face toothed ring 702. Due to the one-way bearing 713, the spur gear 714 will not rotate the pulley rod 712 during reverse rotation. The pawl block 707 of the inner ring of the end face toothed ring 702 presses against the plane of the ratchet 709 and rotates clockwise with the release ring 703. At this time, the release ring 703 rotates eccentrically with the broken strand body 6 through the through hole 710. The force of this eccentric rotation counteracts the stress of the strand body 6 after it breaks, reducing the amplitude of the strand's bounce after it breaks.

[0057] S4. When one of the steel strand bodies 6 breaks, the steel strand body 6 is no longer in a taut state. At this time, the spring telescopic rod 805 elastically recovers and moves the arc-shaped pressure plate 806 down on the surface of the tension plate 5, so that the pressure rod 807 presses against the inclined surface of the trapezoidal pressure block 808, so that the trapezoidal pressure block 808 moves with the elastic clamp 802 into the replacement cone hole 801. At this time, the outer ring of the elastic clamp 802 is pressed by the inner wall of the replacement cone hole 801, so that the elastic clamp 802 closes and clamps the replacement steel wire 803. The replacement steel wire 803 replaces the broken steel strand body 6, so that the tension force is evenly distributed. This avoids the operator not stopping the hydraulic cylinder 4 in time after the steel strand body 6 breaks, which would cause the uneven distribution of tension force and cause other steel strand bodies 6 to break.

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A prestressed tensioning device for concrete bridges, comprising a main support plate (1), characterized in that: A pad (2) is symmetrically fixedly connected to the right side of the main support plate (1), and a secondary support plate (3) is fixedly connected between the two pads (2). A hydraulic cylinder (4) is symmetrically fixedly connected to the right side of the secondary support plate (3), and a tensioning plate (5) is fixedly connected between the two hydraulic cylinders (4). Three steel strand bodies (6) are equidistantly installed in the middle of the main support plate (1), and the three steel strand bodies (6) are installed through the support plate (3) on the surface of the tension plate (5). An elimination mechanism (7) is movably connected between the support plate (3) and the steel strand body (6), and a replacement mechanism (8) is movably connected between the tension plate (5) and the support plate (3). The surface of the replacement mechanism (8) overlaps with the surface of the steel strand body (6). The elimination mechanism (7) includes a movable groove (701) which is located on the left side of the support plate (3). An end face toothed ring (702) is rotatably connected inside the movable groove (701). An elimination ring (703) is provided on the inner ring of the end face toothed ring (702). A support bearing (704) is fixedly connected between the right side of the elimination ring (703) and the inner wall of the movable groove (701). A return coil spring (705) is fixedly connected between the right side of the end face toothed ring (702) and the inner wall of the movable groove (701). The inner ring of the end face toothed ring (702) has eight adjusting grooves (706) equidistantly spaced along the circumference. A pawl block (707) is slidably connected inside the adjusting groove (706). A compression spring (708) is fixedly connected between one end of the pawl block (707) and the inner wall of the adjusting groove (706). A ratchet tooth (709) that cooperates with the pawl block (707) is fixedly connected to the outer ring of the elimination ring (703). A through hole (710) that cooperates with the steel strand body (6) is eccentrically opened in the middle of the elimination ring (703). Both sides of the movable groove (701) are provided with transmission grooves (711). The inner wall of the transmission groove (711) is rotatably connected to a spool rod (712). One end of the spool rod (712) extends into the movable groove (701) and is fixedly sleeved with a one-way bearing (713). The outer ring of the one-way bearing (713) is fixedly sleeved with a spur gear (714). The side wall of the spur gear (714) meshes with the side wall of the end face gear ring (702). A pull rope (716) is provided in the middle of the reel rod (712), and a conical clamp (717) is fixedly installed in the middle of the steel strand body (6). Both ends of the conical clamp (717) are fixedly connected to pull rods (715), and the two pull rods (715) are respectively fixedly connected to one end of the two pull ropes (716). A sealed bearing is fixedly connected to the inner wall of the movable groove (701), and the outer ring of the end face toothed ring (702) is fixedly connected to the inner ring of the sealed bearing. The inner wall of the movable groove (701) is provided with a round hole that matches the through hole (710); A restoring coil spring is fixedly connected between the side wall of the pulley rod (712) and the inner wall of the transmission groove (711), and the pull ropes (716) on the surfaces of the two pulley rods (712) are wound in opposite directions; The replacement mechanism (8) includes a replacement cone hole (801), and there are three replacement cone holes (801). The three replacement cone holes (801) are equidistantly opened at the lower part of the tension plate (5). The three replacement cone holes (801) correspond one-to-one with the three steel strand bodies (6). An elastic clamp (802) is movably inserted into the interior of the replacement cone hole (801). A replacement steel wire (803) is movably inserted between the elastic clamp (802) and the inner wall of the replacement cone hole (801). The left end of the replacement steel wire (803) is fixedly connected to the side wall of the support plate (3). A pad (804) that matches the replacement cone hole (801) is fixedly connected to the upper left side of the tensioning plate (5). A spring telescopic rod (805) is fixedly connected to the bottom of the pad (804). An arc-shaped pressure plate (806) is fixedly connected to the bottom of the spring telescopic rod (805). The middle part of the arc-shaped pressure plate (806) overlaps with the surface of the steel strand body (6). Pressure rods (807) are fixedly connected to both sides of the arc-shaped pressure plate (806). Both sides of the elastic clamp (802) are fixedly connected to trapezoidal pressure blocks (808), and the two trapezoidal pressure blocks (808) correspond one-to-one with the two pressure rods (807). A return spring (809) is fixedly connected between the side wall of the elastic clamp (802) and the side wall of the tensioning plate (5).

2. The prestressing tensioning device for a concrete bridge according to claim 1, characterized in that: A conical limiting block is fixedly connected to the middle of the pressure rod (807), and a limiting spring rod that cooperates with the conical limiting block is symmetrically fixedly connected to the side wall of the tension plate (5).

3. The prestressing tensioning device for a concrete bridge according to claim 2, characterized in that: Both sides of the elastic clamp (802) are fixedly connected to connecting blocks, and the reset spring (809) is fixedly connected between the side wall of the connecting block and the side wall of the tensioning plate (5). The elastic clamp (802) is tapered.

4. The method of using a prestressed tensioning device in a concrete bridge according to claim 1, comprising the following steps: S1. When using this prestressed tensioning device, firstly, one end of the steel strand body (6) is installed on the main support plate (1), and then the other end of the steel strand body (6) passes through the perforation (710) in the middle of the elimination ring (703), the conical clamp (717) and is fixedly installed on the side wall of the tensioning plate (5) from the support plate (3). Then, the conical clamp (717) is fixed on the surface of the steel strand body (6), and at the same time, the arc-shaped pressure plate (806) on the tensioning plate (5) overlaps on the surface of the steel strand body (6). S2. Then, start the hydraulic cylinder (4) to extend and move the tensioning plate (5) to synchronously tension the three steel strand bodies (6) on the tensioning plate (5). As the steel strand bodies (6) are stretched, they will move synchronously with the conical clamp (717), causing the conical clamp (717) to rotate through the pull rope (716) and the sheave rod (712). At this time, the sheave rod (712) drives the spur gear (714) to rotate synchronously through the one-way bearing (713), so that the spur gear (714) meshes with the side wall of the end face gear ring (702) for transmission. During the counterclockwise rotation of the toothed ring (702), when the inclined surface of the pawl block (707) movably set on the inner ring of the end face toothed ring (702) presses against the inclined surface of the ratchet (709), the pawl block (707) slides into the adjusting groove (706), so that the end face toothed ring (702) will not rotate synchronously with the elimination ring (703) when it rotates counterclockwise, and the counterclockwise rotating end face toothed ring (702) carries the reset coil spring (705) to rotate and store energy, while the tensioned steel strand body (6) can limit the rotation of the elimination ring (703); S3. When any steel strand body (6) breaks during tensioning at the left side, the steel strand no longer restricts the elimination ring (703). At the same time, the stored reset spring (705) recovers and rotates clockwise with the end face toothed ring (702). Due to the setting of the one-way bearing (713), the spur gear (714) will not rotate with the wire wheel rod (712) during the reverse process. The pawl block (707) of the inner ring of the end face toothed ring (702) presses against the plane of the ratchet (709) and rotates clockwise with the elimination ring (703). At this time, the elimination ring (703) rotates eccentrically with the broken steel strand body (6) through the through hole (710). The force of this eccentric rotation counteracts the stress of the steel strand body (6) after it breaks, reducing the amplitude of the steel strand after it breaks. S4. When one of the steel strand bodies (6) breaks, the steel strand body (6) is no longer in a taut state. At this time, the spring telescopic rod (805) elastically recovers and moves the arc-shaped pressure plate (806) down on the surface of the tension plate (5), so that the pressure rod (807) presses against the inclined surface of the trapezoidal pressure block (808), so that the trapezoidal pressure block (808) moves with the elastic clamp (802) into the replacement cone hole (801). At this time, the outer ring of the elastic clamp (802) is pressed by the inner wall of the replacement cone hole (801), so that the elastic clamp (802) closes and clamps the replacement steel wire (803), and the replacement steel wire (803) replaces the broken steel strand body (6), so that the tension force is evenly distributed.

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