A pre-tensioning method anchor cable structure, device and construction method thereof

Abstract

This invention discloses a pre-tensioned anchor cable structure, device, and construction method, including prestressed tendons, extruded connecting sleeves, and anchor cups. The extruded connecting sleeves are extruded and formed at the ends of the prestressed tendons. Anchoring connectors and anchor plates, which can move and be fixed relative to the axial direction of the extruded connecting sleeves, are respectively connected to both ends of the extruded connecting sleeves. A tension rod is detachably connected to one end of the anchor cup, and an anchoring hole is provided at the other end of the anchor cup, with the anchoring connector disposed within the anchoring hole. A helical reinforcement is provided on the other side of the anchor plate opposite the anchor cup, and the prestressed tendons pass through the helical reinforcement. This invention combines the advantages of pre-tensioning and post-tensioning methods, applying sufficient compressive stress quickly to the prestressed anchorage section of the component through a combination of gripping and end-face bearing force transmission methods. This avoids quality problems in the component under load caused by prestress loss due to insufficient gripping force. Furthermore, the prestressed tendons are not cut after release and anchoring, improving construction efficiency for systems with multiple prestressed tendons.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, specifically to a pre-tensioned anchor cable structure, device, and construction method. Background Technology

[0002] Prestressed systems are classified into pre-tensioning and post-tensioning methods based on the sequence of concrete pouring and tensioning. Pre-tensioning offers advantages such as simple construction procedures, uniform prestress distribution at all points on the prestressing tendons, and reduced steel consumption (no anchor heads at the anchorage ends). However, it also has drawbacks such as difficulty in smooth turning and significant prestress loss at the anchorage ends. Post-tensioning is adaptable to any construction condition, has minimal prestress loss at the anchorage ends, and can quickly establish prestress. However, it also presents challenges such as complex construction procedures, difficulty in controlling grouting quality, and difficulty in controlling effective prestress due to friction at the anchorage and in the ducts.

[0003] The post-tensioning construction procedure is as follows: arranging prestressing ducts → pouring concrete → curing, tensioning, releasing tension and anchoring → grouting the ducts (to form a whole with the prestressing tendons and to protect the prestressing tendons from corrosion) and anti-corrosion treatment of the anchor heads. Post-tensioning mainly utilizes end anchor plates, anchor pads, and spiral reinforcement to quickly establish end-face prestress, without relying on the prestressing tendons themselves for anchoring.

[0004] For example, patent "CN103726447A" discloses a method and system for a vertical prestressed steel strand anchorage system with low shrinkage after secondary tensioning. This system is a derivative anchorage system of the post-tensioning method to reduce prestress loss. It requires long-term load holding after primary tensioning, followed by secondary tensioning to offset the shrinkage loss caused by the wedge-type anchor and the loss caused by local deformation of the anchor under pressure. Its construction procedure adds a secondary tensioning step to the post-tensioning process, making the construction flow more complex and failing to address the quality risk of incomplete grouting.

[0005] The pre-tensioning construction procedure is as follows: arranging prestressing tendons → tensioning and holding the prestressing tendons → pouring concrete → releasing tension and anchoring → cutting the prestressing tendons → anti-corrosion treatment of the cut surfaces. In the pre-tensioning method, there are no anchor heads after release; anchoring relies solely on the bond between the prestressing tendons and the concrete.

[0006] For example, patent "CN204339983U" discloses a pre-tensioned precast slab beam tie rod type integral tensioning device. The pre-tensioned prestressed concrete precast component is mainly anchored on both sides of two platforms using tools. After tensioning is completed, the concrete component is poured and cured. When the design strength is reached, the tension is released and the prestressing tendons are cut. The prestressing tendons transfer the prestress to the concrete component through their own bond with the concrete.

[0007] However, the aforementioned pre-tensioning method patent has the following drawback: 1. The above technical solution relies entirely on the structure of the prestressing tendon's outer surface and the self-bonding force of the concrete for anchorage. Especially for prestressing tendons with characteristics such as smooth surface, high tensile strength, and dense multi-strand structure, when the self-bonding force between the prestressing tendon and concrete is relatively small compared to the tensile stress of the prestressing tendon, the concrete may be insufficient to support the tensile force of the prestressing tendon, leading to slippage. This results in a sharp increase in prestress loss within a certain range at both ends of the member, such as... Figure 1 The test data shows that the prestress stored within this range is insufficient to resist external loads and does not meet design requirements. Therefore, this pre-tensioning technique is generally unsuitable for applications with short prestressed tendons or where prestressing is required at the ends of the structure, such as the vertical tendons in the web of a box girder.

[0008] 2. The above technical solution requires cutting the prestressed steel bars, which cannot save the amount of prestressed steel bars used. The prestressed steel bars that are not embedded in the concrete cannot be reused as tool rods, which increases steel consumption.

[0009] The information disclosed in the above background section is only intended to enhance the understanding of the overall background of the present invention, and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0010] The purpose of this invention is to provide a pre-tensioned anchor cable structure, device, and construction method thereof. Based on the pre-tensioning construction procedure, it combines the advantages of pre-tensioning and post-tensioning methods. By combining two force transmission methods—gripping and end-face bearing—sufficient compressive stress is rapidly applied to the prestressed anchorage section of the component, avoiding quality problems caused by insufficient gripping force leading to prestress loss when bearing loads. At the same time, the pre-tensioning construction procedure eliminates the grouting process, avoiding the risk of prestressing tendon corrosion due to grouting quality. Furthermore, the prestressing tendons are not cut after release and anchoring, improving construction efficiency for systems with multiple prestressing tendons.

[0011] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A pre-tensioned anchor cable structure includes prestressing tendons, extruded connecting sleeves, and anchor cups. The extruded connecting sleeves are extruded and formed at the ends of the prestressing tendons. An anchoring connectors and anchor plates that can move axially relative to the extruded connecting sleeves are respectively connected to the two ends of the extruded connecting sleeves. A tension rod is detachably connected to one end of the anchor cup, and an anchoring hole is provided at the other end of the anchor cup, in which the anchoring connector is disposed. A helical reinforcement is provided on the other side of the anchor plate opposite to the anchor cup, and the prestressing tendons pass through the helical reinforcements.

[0012] Specifically, the outer surface of the extrusion connecting sleeve is provided with external threads, and the middle part of the anchoring connector and the anchor plate is provided with internal thread holes that are compatible with the external threads of the extrusion connecting sleeve.

[0013] Specifically, the mouth of the anchor cup at one end is provided with an internal thread, and the end of the tension rod is provided with an external thread that matches the internal thread of the anchor cup.

[0014] Preferably, the anchoring connector is a tapered connector, the anchoring hole is a tapered anchoring hole, and the tapered connector is disposed inside the tapered anchoring hole.

[0015] Preferably, the anchoring connector is a spherical connector, the anchoring hole is a spherical surface anchoring hole, and the spherical connector is disposed inside the spherical surface anchoring hole.

[0016] This invention also provides a pre-tensioned anchor cable device, which adopts the pre-tensioned anchor cable structure described above, and further includes a load-bearing support. Tensioning rods I and II at both ends of the prestressed tendon pass through the fixed end and tensioning end of the load-bearing support, respectively. An anchor release device and a load-bearing nut I are sequentially provided at the end of tensioning rod I that passes through the fixed end. Limiting nuts and load-bearing nuts II are respectively provided on tensioning rods II located on the inner and outer sides of the tensioning end. A tensioning platform is also provided on the outer side of the tensioning end. Tensioning rods II pass through the tensioning platform and are provided with tensioning nuts. A jack is provided between the tensioning platform and the fixed end.

[0017] The present invention also provides a construction method for a pre-tensioned anchor cable device, which uses the pre-tensioned anchor cable device described above and includes the following steps: S1: Build a load-bearing support, install and connect the pre-tensioned anchor cable structure, and install load-bearing nut I, load-bearing nut II, tension nut, limit nut and anchor release device on both sides of the load-bearing support; S2: Use load-bearing brackets and jacks to tension the pre-tensioned anchor cable device. After tensioning to the control stress, adjust the anchor plate and spiral reinforcement to the preset position, and lock the load-bearing nut II at the tensioning end. S3: Pour concrete components and cure them to meet design requirements; S4: Tighten the limit nut, and when the tensioning end jack is tensioned to the point where it can turn the load-bearing nut II, loosen the load-bearing nut II and unload the tension with the jack; at the same time, start the fixed end anchor release device to unload and release the tension. S5: After tensioning is completed, first separate the contact surfaces of the anchoring connector and the anchor cup, then loosen and disassemble the anchor cup and anchoring connector in sequence to complete the fabrication of the pre-tensioned prestressed concrete component.

[0018] The beneficial effects of this invention are: 1. The pre-tensioning method uses anchor heads to participate in force transmission and is supplemented by end bearing pads and spiral reinforcement to expand the force transmission area. It does not rely solely on gripping friction to transmit loads. This allows sufficient stress to be stored at both ends of the component where prestress is applied, reducing the prestress loss caused by the elastic recoil of the steel strands at both ends.

[0019] 2. The steel strand anchorage adopts a compression anchor head, ensuring a fixed anchorage position and preventing the prestressing tendon retraction loss seen with wedge-type anchors. The fully threaded construction of the compression anchor head allows for adjustment of the spiral reinforcement position after prestressing, correcting for production errors in cable length, tensioning elongation errors, and construction and installation errors. This adapts to the location of the casting formwork and ensures that prestress is applied from the designed position.

[0020] 3. This solution employs either a conical or spherical contact structure at the anchorage connection, and this connection utilizes a combined structure. The conical structure adaptively ensures the connecting sleeve and the compression anchor head are coaxial during tensioning. After stress relief, a gentle tap to disengage the conical contact and then twisting the threads facilitates separation. The spherical structure addresses the issue of misalignment. Therefore, even if the components are misaligned during use, this type of combined structure allows for easy disengagement after stress relief.

[0021] 4. In this scheme, the prestressed tendons not embedded in the concrete are reused as tool tie rods to reduce steel consumption and improve economic efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the test data of the pre-tensioning method without anchor plates in the background technology of this invention.

[0023] Figure 2 This is a schematic diagram of a pre-tensioned anchor cable structure according to Example 1.

[0024] Figure 3 This is a schematic diagram of the first embodiment of a pre-tensioned anchor cable structure in Example 2.

[0025] Figure 4 This is a schematic diagram of a second embodiment of a pre-tensioned anchor cable structure in Example 2.

[0026] Figure 5 This is a schematic diagram of the traditional connection structure applied to the pre-tensioning method in Example 2.

[0027] Figure 6 This is a schematic diagram of a pre-tensioned anchor cable device according to Example 3.

[0028] Figure 7 This is a flowchart of a construction method for a pre-tensioned anchor cable device, as shown in Example 3.

[0029] In the figure, 1-tensioning rod, 101-tensioning rod I, 102-tensioning rod II, 2-anchoring connector, 3-anchor cup, 4-extrusion connector sleeve, 5-anchor plate, 6-spiral reinforcement, 7-prestressing tendon, 8-load-bearing bracket, 9-anchoring release device, 10-load-bearing nut I, 11-limiting nut, 12-load-bearing nut II, 13-tensioning platform, 14-tensioning nut, 15-jack, 16-concrete component, 17-pre-tensioned anchor cable structure. Detailed Implementation

[0030] To illustrate the technical content, objectives, and effects of this invention in detail, the following description is provided in conjunction with embodiments and accompanying drawings. In the description of the embodiments, it should be understood that terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing this embodiment and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation—or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Example 1

[0031] According to a specific implementation of this scheme, a pre-tensioned anchor cable structure is provided, such as... Figure 2 As shown, it mainly includes: tension rod 1, anchoring connector 2, anchor cup 3, extrusion connector 4, anchor plate 5, spiral reinforcement 6, and prestressing tendon 7.

[0032] Tensioning rod 1: Used to tension the pre-tensioned anchor cable device. Tensioning rod 1 can also be replaced with other equivalent connecting components for tensioning, such as high-strength steel bars, threaded steel bars, prestressed cables and other high-strength steel materials that can be reused for tensioning operations. Anchor connector 2 and anchor cup 3 are used as anchor connection components to connect compression sleeve 4 and tension rod 1. Because compression sleeve 4 will solidify with concrete before unloading, a combination kit is adopted to correct the stress concentration and difficulty in disassembly caused by the influence of misalignment due to construction errors. Extrusion connecting sleeve 4 and prestressing tendon 7: By extrusion, internal stress is generated between the metals of extrusion connecting sleeve 4 and prestressing tendon 7. The prestressing tendon 7 is anchored to extrusion connecting sleeve 4 by gripping. Threads or pin slots are provided on its outer surface for connection. The relative positions of anchor plate 5 and anchoring connector 2 on extrusion connecting sleeve 4 can be adjusted. Anchor plate 5 and spiral reinforcement 6: Anchor plate 5 is used to quickly establish the prestressed end face force transmission state and expand the concentrated load force transmission area. Spiral reinforcement 6 is used to constrain the core concrete of local bearing and improve the bearing capacity of the concrete under the anchor. The two are fixedly connected to form the anchor force transmission component in the local disturbance zone. The component can be adjusted in position on the extrusion connecting sleeve 4 to ensure the position of the prestressed end.

[0033] The connection relationship of the above structural components is as follows: the extrusion connecting sleeve 4 is extruded and formed at the end of the prestressing tendon 7, and the two ends of the extrusion connecting sleeve 4 are respectively connected to the anchoring connecting head 2 and the anchor plate 5, which can move relative to its axial direction; one end of the anchor cup 3 is detachably connected to the tension rod 1, and the other end of the anchor cup 3 is provided with an anchoring hole, and the anchoring connecting head 2 is provided in the anchoring hole; a spiral reinforcement 6 is provided on the other side of the anchor plate 5 opposite to the anchor cup 3, and the prestressing tendon 7 passes through the spiral reinforcement 6.

[0034] The principle of this embodiment is: The structure of this embodiment is mainly applicable to the construction of prestressed pretensioning method. Since both ends are anchored when the cable-bearing unit is made, the relative positions of the extrusion connecting sleeve 4 and the prestressing tendon 7 are determined. Therefore, the elongation value generated by the tensioning of the cable must be calculated and considered during cable making to control the anchor plate 5 to be in the expected position after tensioning. During cable making and construction, manufacturing and construction errors are inevitable. Therefore, after tensioning, the extrusion connecting sleeve 4 usually deviates from the expected position. The adjustable property of the anchor plate 5 at the extrusion connecting sleeve 4 can be used to adjust the anchor plate 5 to the expected position before pouring. When the concrete reaches the strength and the tool end is unloaded and tensioned, the bonding effect of the anchor plate 5, the spiral reinforcement 6 and the prestressing tendon 7 jointly bears and transmits the tensile stress stored in the prestressing tendon 7, producing the expected prestressing stress effect.

[0035] During unloading and anchoring, due to the unidirectional limiting between the anchor cup 3 and the anchoring connector 2, the anchoring connection component, the extrusion connector sleeve 4, and the anchoring connection component are not in complete rigid contact. They can be separated by gently tapping after unloading, thereby reducing or eliminating angular errors caused by construction. The tools and fixtures are easy to disassemble, the stress concentration of the anchoring connection component is small, and it can be reused multiple times. When the concrete component 16 is cured to the point where it can be unloaded and tensioned, in order to save steel consumption, the prestressing tendons are not cut, the anchoring method that relies solely on the self-bonding of prestress and concrete is not used, and all steel components not embedded in the concrete component are not cut. Therefore, unloading is required at both ends, and reusable steel components other than the extrusion connector sleeve 4, the anchor plate 5, and the spiral reinforcement 6 are disassembled. This is a usage that does not exist in the conventional pre-tensioning method.

[0036] In this preferred embodiment, the cup mouth at one end of the anchor cup 3 is provided with an internal thread, and the end of the tension rod 1 is provided with an external thread that matches the internal thread of the anchor cup 3. The anchoring connector 2 is a tapered connector, and the anchoring hole is a tapered anchoring hole, with the tapered connector disposed within the tapered anchoring hole. This solution uses threaded connections for both disassembly and axial movement adjustment, resulting in a simple and unified structure. Example 2

[0037] Traditional pre-tensioning connection methods use an integral connecting sleeve with a wedge-type anchor at one end. During tensioning, the wedge-type anchor deflects from the wedge, preventing misalignment at the threaded connection. Furthermore, after unwinding and releasing the prestressing tendon, the end of the connecting sleeve connected to the prestressing tendon becomes a free end, allowing for twisting separation between the tension rod and the connecting sleeve. However, if the anchor head is embedded in the concrete as a load-bearing component, the prestressing tendon and anchor head are not cut off, and both sides of the connecting sleeve are rigidly threaded connections. Figure 5 As shown, if the tension rod, connecting sleeve, and extrusion anchor head are out of axis due to construction errors, they cannot be separated by twisting the thread.

[0038] This embodiment, based on Embodiment 1, addresses the issues of stress concentration and difficulty in disassembly of components caused by the influence of misalignment due to construction errors. The assembly kit can employ two different structural forms.

[0039] One way is as follows Figure 3 Anchor joint 2 is a spherical connector, and the anchor hole is a spherical surface anchor hole. The spherical connector is set inside the spherical surface anchor hole. By using spherical contact, the angular error introduced during construction is adaptively deflected during tensioning, reducing the deflection error at the rigid connection.

[0040] Another way is as follows Figure 4 Anchor connector 2 is a tapered connector, and the anchor hole is a tapered anchor hole. The tapered connector is set inside the tapered anchor hole. Using tapered surface contact, the angular error introduced during construction is adaptively aligned during tensioning. The connection between the tapered connector and tension rod 1 has a larger gap and a higher safety factor for introducing engineering deflection error angle. The tapered structure adapts to the coaxiality of the anchor cup 3 and anchor connector 2 during tensioning. After unloading, gently tap to remove the tapered surface contact and then twist the thread for easy separation. Example 3

[0041] This embodiment provides a pre-tensioned anchor cable device employing the pre-tensioned anchor cable structure 17 of Embodiments 1 and 2, specifically as follows: Figure 6 As shown, it also includes a load-bearing bracket 8. Tension rods I101 and II102 at both ends of the prestressed tendon 7 pass through the fixed end and tensioning end of the load-bearing bracket 8, respectively. An anchor release device 9 and load-bearing nut I10 are sequentially provided at the end of tension rod I101 that passes through the fixed end. Limiting nuts 11 and load-bearing nuts II12 are respectively provided on tension rods II102 located on the inner and outer sides of the tensioning end. A tensioning platform 13 is also provided on the outer side of the tensioning end. Tension rods II102 pass through the tensioning platform 13 and are provided with tensioning nuts 14. A jack 15 is provided between the tensioning platform 13 and the fixed end.

[0042] The specific construction method of the pre-tensioned anchor cable device in this embodiment is as follows: S1: Construct a load-bearing support 8, which can be horizontal or vertical depending on the characteristics of the prestressed components, and is used to support the prestressed tendons 7 for tensioning. Install and connect the pre-tensioned anchor cable structure 17. Install load-bearing nuts I10, II12, tensioning nuts 14, limit nuts 11 and anchor release devices 9 such as wedge anchor release, electrofusion anchor release, sandbox anchor release, etc. on both sides of the load-bearing support 8 for temporary anchoring after tensioning and unloading the tension force.

[0043] S2: Tension the pre-tensioned anchor cable device using the load-bearing bracket 8 and jack 15. At this time, the limiting nut 11 should leave space and not contact the load-bearing bracket 8. After tensioning to the control stress, adjust the anchor plate 5 and spiral reinforcement 6 to the expected position; lock the tensioning end load-bearing nut II12.

[0044] S3: Pour concrete component 16 and cure it to meet design requirements.

[0045] S4: Tighten the limit nut 11 to ensure that the unloading process does not affect the pre-tensioned anchor cable. When the tensioning end jack 15 tensions the cable to the point where the load-bearing nut II12 can be turned, loosen the load-bearing nut II12 and then unload the tension using the jack 15. At the same time, start the fixed end anchor release device 9 to unload and release the tension simultaneously.

[0046] S5: After the tensioning is completed, all stress is transferred to the pre-tensioned anchor cable device, and the tension rod 1 no longer retains tensile stress. Then, through the special structure of the anchor cable connection, the contact surface between the anchor connector 2 and the anchor cup 3 is first separated, and then the anchor cup 3 and the anchor connector 2 are loosened and disassembled in sequence. The pre-tensioned prestressed concrete member 16 is lifted out or the load-bearing bracket 8 is moved to the next concrete member 16 for fabrication. The above steps are repeated to finally complete the fabrication of the pre-tensioned prestressed concrete beam.

[0047] Although the present invention has been described in detail above with specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A pre-tensioned anchor cable structure, characterized in that, The system includes prestressed tendons (7), extruded connecting sleeves (4), and anchor cups (3). The extruded connecting sleeves (4) are extruded and formed at the ends of the prestressed tendons (7). Anchor connecting heads (2) and anchor plates (5) that can move axially relative to the extruded connecting sleeves (4) are respectively connected to both ends of the extruded connecting sleeves (4). One end of the anchor cup (3) is detachably connected to a tension rod (1), and the other end of the anchor cup (3) is provided with an anchor hole, in which the anchor connecting head (2) is provided. A spiral reinforcement (6) is provided on the other side of the anchor plate (5) opposite to the anchor cup (3). The reinforcing bar (7) is inserted into the spiral bar (6); the anchoring connector (2) is a conical connector or a spherical connector, and the anchoring hole is a conical anchoring hole or a spherical anchoring hole that is compatible with the anchoring connector; the outer surface of the extrusion connector (4) is provided with an external thread, and the middle part of the anchoring connector (2) and the anchor plate (5) is provided with an internal thread hole that is compatible with the external thread of the extrusion connector (4); the cup mouth at one end of the anchor cup (3) is provided with an internal thread, and the end of the tension rod (1) is provided with an external thread that is compatible with the internal thread of the anchor cup (3).

2. A pre-tensioned anchor cable device, employing the pre-tensioned anchor cable structure (17) as described in claim 1, characterized in that, It also includes a support bracket (8), and tension rods I (101) and II (102) at both ends of the prestressed tendon (7) pass through the fixed end and tensioning end of the support bracket (8) respectively. The end of tension rod I (101) that passes through the fixed end is provided with a release anchor device (9) and a load-bearing nut I (10) in sequence. Limit nuts (11) and load-bearing nuts II (12) are respectively provided on tension rods II (102) located on the inner and outer sides of the tensioning end. A tensioning platform (13) is also provided on the outer side of the tensioning end. The tension rod II (102) passes through the tensioning platform (13) and is provided with a tensioning nut (14). A jack (15) is provided between the tensioning platform (13) and the fixed end.

3. A construction method for a pre-tensioned anchor cable device, which employs the pre-tensioned anchor cable device as described in claim 2, characterized in that, Includes the following steps: S1: Build a load-bearing bracket (8), install and connect the pre-tensioned anchor cable structure (17), and install load-bearing nut I (10), load-bearing nut II (12), tension nut (14), limit nut (11) and anchor release device (9) on both sides of the load-bearing bracket (8). S2: Use the load-bearing bracket (8) and jack (15) to tension the pre-tensioned anchor cable device. After tensioning to the control stress, adjust the anchor plate (5) and spiral reinforcement (6) to the preset position and lock the load-bearing nut II (12) at the tensioning end. S3: Pour concrete components (16) and cure them to meet design requirements; S4: Tighten the limit nut (11), and when the tensioning end jack (15) tensions the load-bearing nut II (12) to the point where it can be turned, loosen the load-bearing nut II (12), and unload the tension by the jack (15); at the same time, start the fixed end anchor release device (9) to unload the tension. S5: After the tensioning is completed, first separate the contact surfaces of the anchoring connector (2) and the anchor cup (3), and then loosen and disassemble the anchor cup (3) and the anchoring connector (2) in sequence to complete the fabrication of the pre-tensioned prestressed concrete member (16).

Images