A secondary tensioning reaction frame

Abstract

The utility model provides a kind of for secondary tension counterforce frame.The used secondary tension counterforce frame includes frame body and backing plate, the frame body includes two interval arrangement's side plate and the panel connected in one end of two side plate, the side plate is connected with backing plate in one end away from panel, the area of backing plate is greater than the cross-sectional area of side plate, and tension hole is set on the panel.The utility model increases the contact area with the surface of concrete by backing plate, can scatter the reaction force of jack to the position far away from the core area of tension slot, effectively avoids the weak area of concrete at slot, effectively avoids the phenomenon such as cracking and crushing of concrete surface, ensures the construction quality and structure safety of prestress, greatly saves the maintenance cost of bridge later period.

Description

Technical Field

[0001] This utility model relates to the field of bridge construction technology, and in particular to a reaction frame for secondary tensioning. Background Technology

[0002] Post-tensioning of prestressed bridge components utilizes tools such as jacks, tool anchors, tool clamps, and limiting plates. Prestressing tendons (multiple steel strands forming a bundle) are embedded in the concrete, and anchor plates are present on the concrete surface through which the prestressing tendons pass. During construction, the front end of the jack is placed against the limiting plate, and the rear end of the jack clamps the prestressing tendons using tool anchors and tool clamps. The jack applies tension to the prestressing, while simultaneously transferring the reaction force to the concrete through the limiting plate and anchor plates. After tensioning, during release, the prestressing tendons inevitably retract (the retraction value is approximately the depth of the limiting plate groove, typically 6mm) when the working clamps retract to the working anchor. For longer prestressing tendons, the retraction is small and can be compensated for by overtensioning. However, for shorter prestressing tendons (4-6 meters in length), the retraction is approximately 6mm, resulting in a prestress loss of 20-30%, which will affect the construction quality and structural safety. Therefore, secondary tensioning is necessary to replenish the prestress.

[0003] Because the retraction of the prestressing tendons during the first tensioning is unavoidable, the second tensioning typically employs a low-retraction working anchor, nut, tension rod, and tensioning bucket. The tensioning bucket has internal threads at both ends, and the low-retraction working anchor has threads on its outer surface. First, the nut is connected to the low-retraction working anchor wire via the threads. Then, the tensioning bucket is connected to the low-retraction working anchor wire. Finally, one end of the tension rod is connected to the threaded end of the tensioning bucket, and the other end of the tension rod passes through a jack and is then connected and secured to the tension rod via the tensioning working anchor. The low-retraction working anchor is tensioned using the jack. After tensioning to the control stress, the jack cylinder lifts, detaching the lower end of the low-retraction working anchor from the anchor plate. While holding the load, the nut of the working anchor is rotated towards the anchor plate to eliminate the gap between the low-retraction working anchor and the anchor plate. Then, the jack is depressurized, releasing the tension. The low-retraction working anchor is locked in place, thus eliminating the stress loss caused by anchor retraction during the first tensioning release. This completes the second tensioning process.

[0004] During the secondary tensioning process, the concrete surface around the tensioning slot of the prestressing tendon is usually not on a single plane. If the concrete surface is curved or folded, the jack cannot be stably applied to the concrete surface. Moreover, the concrete surface around the tensioning slot is relatively thin, and if the jack is directly stressed on it, cracking and crushing will occur. Utility Model Content

[0005] The purpose of this invention is to provide a secondary tensioning reaction frame that is suitable for secondary tensioning of concrete surfaces around uneven tensioning slots.

[0006] The technical solution of this utility model is: a secondary tensioning reaction frame, including a frame body and a pad plate. The frame body includes two spaced-apart side plates and a panel connected to one end of the two side plates. The end of the side plate away from the panel plate is connected to the pad plate. The area of ​​the pad plate is larger than the cross-sectional area of ​​the side plate. Tensioning holes are provided on the panel plate.

[0007] Preferably, a reinforcing plate is connected between the side plate and the front panel, and multiple reinforcing plates are spaced apart.

[0008] Preferably, the reinforcing plate includes a first stiffener and a second stiffener, the projection of the first stiffener on the panel forms a length L1, the projection of the second stiffener on the panel forms a length L2, L1>L2, and the second stiffener is disposed close to the tensioning hole.

[0009] Preferably, a gap δ1 is formed between the first stiffeners connecting the two side plates, and a gap δ2 is formed between the second stiffeners connecting the two side plates, where δ2 > the diameter of the tensioning hole.

[0010] Preferably, the reinforcing plate is triangular.

[0011] Preferably, the two side plates are provided with lifting lugs on the side that is far apart from each other, and the lifting lugs are provided with lifting holes.

[0012] Preferably, the side plate is provided with at least one transport hole for passing through the reinforcing bar.

[0013] Compared with related technologies, the beneficial effects of this utility model are as follows:

[0014] I. This utility model is designed with an integrated panel and side plate, and also has a pad plate that can support on the concrete surface. Tensioning holes are set on the panel. When the jack is applied to the reaction frame of this utility model, the pad plate increases the contact area with the concrete surface, which can disperse the reaction force of the jack to a position far away from the core area of ​​the tensioning slot, effectively avoiding the weak area of ​​the concrete at the slot, effectively preventing cracking and crushing of the concrete surface, ensuring the construction quality and structural safety of prestressing, and greatly saving the later maintenance costs of the bridge.

[0015] Second, the pad of this utility model, with an area larger than the side plate, can fit closely to the concrete surface, better dispersing the reaction force of the jack. If the concrete surface is too curved or has too many folds, the shape of the bottom of the side plate is cut on-site to match the concrete surface. Because the cut surface is rough, it is ground and then pads of different thicknesses are welded on-site to prevent stress concentration caused by the rough and uneven cut surface from damaging the concrete. This can achieve the purpose of adjusting or eliminating the mismatch between the side plate and the concrete surface, avoiding the impact on prestressing tension, and effectively solving the problem that the jack cannot directly act on the concrete surface in this scenario.

[0016] Third, this utility model is equipped with lifting lugs and transport holes on the side plate, which can be used to transport the components by hoisting or inserting steel bars, so that they can be better placed at the slot and improve the accuracy of the installation of the reaction frame, tension rod and jack. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the secondary tensioning reaction frame provided by this utility model;

[0018] Figure 2 For along Figure 1 A-direction diagram in the diagram;

[0019] Figure 3 For along Figure 2 A schematic diagram of direction B in the diagram.

[0020] In the attached diagram: 1. Frame; 11. Panel; 111. Tensioning hole; 12. Side plate; 121. Transport hole; 13. Reinforcing plate; 131. First stiffening plate; 132. Second stiffening plate; 2. Pad plate; 3. Lifting lug; 31. Lifting hole. Detailed Implementation

[0021] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0022] like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment provides a secondary tensioning reaction frame including a frame body 1, a pad plate 2, and lifting lugs 3. The frame body 1 includes two spaced-apart side plates 12 and a panel 11 connected to one end of the two side plates 12. The end of the side plate 12 away from the panel 11 is connected to the pad plate 2, the area of ​​the pad plate 2 is larger than the cross-sectional area of ​​the side plate 12, and the panel 11 has tensioning holes 111.

[0023] A reinforcing plate 13 is connected between the side plate 12 and the front panel 11, and multiple reinforcing plates 13 are spaced apart. The reinforcing plate 13 is triangular.

[0024] like Figure 2 As shown, the reinforcing plate 13 includes a first stiffener 131 and a second stiffener 132. The projection of the first stiffener 131 onto the panel 11 forms a length L1, and the projection of the second stiffener 132 onto the panel 11 forms a length L2, where L1 > L2. The second stiffener 132 is positioned close to the tension hole 111.

[0025] A gap δ1 is formed between the first stiffening plates 131 connected to the two side plates 12, and a gap δ2 is formed between the second stiffening plates 132 connected to the two side plates 12, where δ2 is greater than the diameter of the tensioning hole 111.

[0026] Lifting lugs 3 are provided on the side of the two side plates 12 that are far apart from each other, and lifting lugs 3 are provided with lifting holes 31. Each side plate 12 is provided with at least one handling hole 121 for passing through reinforcing bars.

[0027] In this embodiment, the panel 11 is 50cm long, 40cm wide, and 4cm thick. The side panel 12 is 54cm long, 8cm wide, and 1cm thick. The lifting lug 3 is a steel plate, 5cm long, 5cm wide, and 1cm thick. The panel 11, side panel 12, and pad 2 are manually arc-welded on-site. The tensioning hole 111 has a diameter of 12cm. The transport hole 121 has a diameter of 3cm. The lifting hole 31 has a diameter of 3cm.

[0028] The triangular reinforcing plate 13 has a base of 11cm, a height of 15cm, and a thickness of 2cm. The reinforcing plate 13 serves a reinforcing function. The reinforcing plate 13 is manually arc-welded on-site. δ1=10cm ensures sufficient space for workers to operate the nut tightening tool. The reinforcing plates 13 on the two side plates 12 are symmetrically arranged. The reinforcing plates 13 on a single side plate 12 are equidistantly arranged.

[0029] In use, the worker inserts a reinforcing bar into the transport hole 121 and uses the reinforcing bar to transport the reaction frame to the tensioning position. Then, the hook of the hand-operated hoist is passed through the lifting hole 31 and hooked onto the lifting lug 3. The hand-operated hoist is used to lift the reaction frame to the secondary tensioning slot. The low-retraction working anchor, nut, tensioning rod, and tensioning bucket are then connected in the existing manner. The end of the tensioning rod furthest from the low-retraction working anchor is then passed through the tensioning hole 111 and connected to the jack. The pad 2 on the reaction frame is pressed tightly against the concrete surface surrounding the tensioning slot, and the jack is pressed tightly against the upper surface of the panel 11. The jack is activated to perform secondary tensioning on the low-retraction working anchor. After completion, the nut is tightened using a tool, tilting it towards the anchor plate side (the side furthest from the jack) to eliminate the gap between the low-retraction working anchor and the anchor plate. At this point, the low-retraction working anchor is locked in place, completing the secondary tensioning.

[0030] This invention disperses the reaction force of the jack to a position far from the core area of ​​the tensioning slot, effectively avoiding the weak areas around the slot. The stress is also dispersed onto the concrete surface around the slot through the reaction frame, preventing the jack from acting directly on the area around the slot, which could cause concrete cracking or crushing. This ensures the construction quality and structural safety of the prestressed concrete and greatly saves on the later maintenance costs of the bridge.

[0031] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A reaction frame for secondary tensioning, comprising a frame body (1), characterized in that, It also includes a pad (2). The frame (1) includes two spaced side plates (12) and a panel (11) connected to one end of the two side plates (12). The side plate (12) is connected to the pad (2) at the end away from the panel (11). The area of ​​the pad (2) is larger than the cross-sectional area of ​​the side plate (12). Tensioning holes (111) are provided on the panel (11).

2. The reaction frame for secondary tensioning according to claim 1, characterized in that, A reinforcing plate (13) is connected between the side plate (12) and the front panel (11), and multiple reinforcing plates (13) are arranged at intervals.

3. The reaction frame for secondary tensioning according to claim 2, characterized in that, The reinforcing plate (13) includes a first stiffener (131) and a second stiffener (132). The projection of the first stiffener (131) on the panel (11) forms a length L1, and the projection of the second stiffener (132) on the panel (11) forms a length L2, where L1 > L2. The second stiffener (132) is located near the tensioning hole (111).

4. The reaction frame for secondary tensioning according to claim 3, characterized in that, A gap δ1 is formed between the first stiffening plate (131) connected to the two side plates (12), and a gap δ2 is formed between the second stiffening plate (132) connected to the two side plates (12), where δ2 > the diameter of the tensioning hole (111).

5. The reaction frame for secondary tensioning according to claim 2, characterized in that, The reinforcing plate (13) is triangular.

6. The reaction frame for secondary tensioning according to claim 1, characterized in that, The two side plates (12) are provided with lifting lugs (3) on the side that is far apart from each other, and the lifting lugs (3) are provided with lifting holes (31).

7. The reaction frame for secondary tensioning according to claim 1, characterized in that, The side plate (12) is provided with at least one transport hole (121) for passing through reinforcing bars.

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