Web tension groove combined steel form structure and construction method

Abstract

The present application relates to the technical field of bridge construction, and more particularly to a kind of web tension groove combined steel mould structure and construction method.The device is mainly composed of tension groove steel mould, comb slot, flat metal bellows, reserved hole, web tension hole, anchorage device, anchor pad and the like.The main function is to solve the current pouring box girder web tension groove construction and the existing inconvenience and quality defect problem during later tensioning.Compared with the traditional method, the construction method and steel mould device do not need to remove the concrete around the tension groove to the leakage of muscle, avoid damaging the structure of tension groove, can ensure the welding length of reinforcing steel, save labor time and cost, improve efficiency and reinforcement quality.At the same time, it solves the complex construction of reinforcing steel, bellows, steel strand and other structures at the tension groove, ensures the web tension operation space, and avoids the conflict problem between each structure at the slot.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a combined steel formwork structure for web tensioning channels and its construction method. Background Technology

[0002] Prestressing tensioning of box girders is a key process in bridge construction, which directly determines the service life of the bridge. Currently, the tensioning end of the web of cast-in-place box girders is usually constructed by reserving tensioning slots. The local stress at the tensioning end is very large. In order to ensure the tensioning quality of the web of cast-in-place box girders, tensioning slots need to be set at its end. The existing construction method has the following defects: (1) In order to ensure the tensioning operation space, the transverse ordinary steel bars of the top plate of the box girder and the longitudinal steel bars and stirrups of the web need to be cut off at the tensioning slot, and the tensioning is carried out after the tensioning is completed. For reinforcement welding, it is necessary to remove the concrete around the tensioning slot to expose enough reinforcing steel bars. This damages the structure of the tensioning slot and wastes manpower, causing great inconvenience to the construction. (2) In addition, for designs with transverse prestressed tensioning systems, flat metal corrugated pipes need to be pre-embedded at certain intervals. At this time, the transversely arranged corrugated pipes often avoid or omit the tensioning slot. When they collide with ordinary steel bars, the position of the prestressed steel strand pipes is prioritized. If the construction is not carried out according to the design drawings, it will affect the tensioning effect and quality in the later stage. (3) Traditional wooden formwork is prone to deformation during the pouring process, reducing the number of turnovers and affecting the structure of the tensioning slot. It is also prone to leakage of grout during pouring, resulting in difficulty in demolding. After use, it is scrapped and cannot be recycled, causing waste. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a combined steel formwork structure and construction method for web tensioning groove, which can improve the quality of reinforcement welding after the steel bars are cut off at the tensioning groove opening and the quality of transverse tensioning of the top plate, and is easy to disassemble and reassemble and can be reused.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A combined steel mold structure for web tensioning grooves, located at the opening of the tensioning groove, includes a tensioning groove steel mold 1 with a triangular prism-shaped box structure. The tensioning groove steel mold 1 is composed of a bottom plate, a left side plate, a right side plate, and a front plate. Both the left and right side plates have equally spaced comb-shaped grooves 2, through which reinforcing bars 9 pass. Both the left and right side plates have reserved holes 4 in the middle, and flat metal corrugated pipes 3 are pre-embedded in the reserved holes 4. Transverse steel strands pass through the flat metal corrugated pipes 3. The front plate has a web tensioning hole 5 in the middle, through which longitudinal steel strands pass. An anchor 6 is provided on the web tensioning hole 5.

[0006] Furthermore, the base plate, left side plate, right side plate, and front plate are all made of steel.

[0007] Furthermore, the top of the tensioning groove steel mold 1 is higher than the top elevation of the box girder concrete.

[0008] Furthermore, a circular metal corrugated pipe is pre-embedded in the web tensioning hole 5.

[0009] Furthermore, an anchor plate 7 is provided between the web tensioning hole 5 and the anchor 6.

[0010] Furthermore, the anchor plate 7 has grouting holes on its edge.

[0011] Furthermore, the base plate, left side plate, right side plate, and front plate are all coated with a release agent.

[0012] Furthermore, the gaps in the comb-shaped groove 2 are filled with foam adhesive.

[0013] Furthermore, the gaps between the reserved hole 4 and the web tensioning hole 5 are sealed with foam adhesive.

[0014] A construction method for a web tensioning groove combined steel formwork, based on the web tensioning groove combined steel formwork structure described above, is characterized by comprising the following steps:

[0015] S1. Operation preparation: Lay out the size and position of the tensioning groove at the top plate and web of the box girder according to the preset location, and make the tensioning groove steel mold according to the laid-out size, and open the comb-shaped groove according to the spacing of the reinforcing bars.

[0016] S2. After applying release agent to the assembled tensioning groove steel mold, install it at the tensioning groove opening and adjust the height so that the top of the steel mold is higher than the preset top elevation H of the box girder concrete.

[0017] S3, install the anchor plate and anchorage of the web tensioning hole in sequence, and the transverse flat metal corrugated pipe and steel bar;

[0018] S4, cut off the corrugated pipe inside the tensioning groove, leave a pre-set length of joint on both sides, and cut the steel bar inside the tensioning groove in the middle and bend it vertically upward at about 135°.

[0019] S5, place the jack into the tensioning slot, first tension the longitudinal steel strand bundles at the web, the longitudinal prestressed steel strands are steel strands with a tensile strength of fpk=Φs15.2, after the web tensioning is completed, grouting and anchoring are carried out in time, and then curing is performed;

[0020] S6. After the anchor is sealed, restore the corrugated pipe at the cut-off point and seal the joint tightly. Then install the transverse prestressed steel strands of the top plate. The transverse prestressed steel strands also use steel strands with a tensile strength of fpk=Φs15.2.

[0021] S7, restore the steel bars inside the tensioning groove to the horizontal lap position, and reinforce the lap joint with full welding on one side, with a weld length L≥10d, where d is the diameter of the steel bar;

[0022] After the steel mesh inside the tensioning channel is welded and reinforced, the tensioning channel concrete is poured and compacted using a manual immersion vibrator.

[0023] Compared with the prior art, the present invention has the following main advantages:

[0024] 1. This application eliminates the need to chisel away the concrete around the tensioning channel to expose the reinforcing bars, thus avoiding damage to the structure of the tensioning channel, ensuring the welding length of the reinforcing bars, saving labor time and costs, and improving efficiency and reinforcement quality.

[0025] 2. By threading steel strands through the transverse corrugated pipe section later, sufficient space is ensured for web tensioning, while not affecting subsequent transverse tensioning, grouting, and anchoring processes.

[0026] 3. By reserving sufficient steel bar welding length and corrugated pipe joint length, there is no need to chisel away the concrete around the tensioning slot, thus avoiding damage to the appearance and structure of the tensioning slot and saving labor time and costs.

[0027] 4. Compared with wooden formwork, the combined steel formwork of this application improves the overall performance and stability, the groove is not easily deformed during the pouring of the box girder top slab, and the appearance quality after demolding is good.

[0028] 5. The combined steel mold and comb-shaped groove of this application facilitate convenient installation and dismantling before and after construction, without affecting the construction of each process, and is conducive to material turnover and recycling.

[0029] 6. During the box girder casting process, foam adhesive was used to seal the comb-shaped grooves and corrugated pipe joints on the steel plate to prevent grout leakage, ensure the tensioning groove structure and facilitate demolding, and further improve the construction technology level of the tensioning groove. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the tensioning groove steel mold in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the installation of the grooved steel bars in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the groove reinforcement welding in an embodiment of the present invention.

[0033] In the figure: 1. Tensioning groove steel mold; 2. Comb-shaped groove; 3. Flat metal corrugated pipe; 4. Reserved hole; 5. Web tensioning hole; 6. Anchor; 7. Anchor plate; 8. Steel strand; 9. Reinforcing bar. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0036] I. A composite steel mold structure for web tensioning grooves

[0037] like Figures 1-3 As shown, according to an embodiment of the present invention, a web tensioning groove combined steel mold structure is provided at the tensioning groove opening position, including a tensioning groove steel mold 1 with a triangular prism box structure.

[0038] The tensioning groove steel mold 1 is composed of a base plate, a left side plate, a right side plate, and a front plate. The left side plate and the right side plate are both provided with equally spaced comb-shaped grooves 2. The comb-shaped grooves 2 are threaded with reinforcing bars 9. The left side plate and the right side plate are both provided with reserved holes 4 in the middle. The reserved holes 4 are pre-embedded with flat metal corrugated pipes 3. The flat metal corrugated pipes 3 are threaded with transverse steel strands. The front plate is provided with a web tensioning hole 5 in the middle. The web tensioning hole 5 is threaded with longitudinal steel strands. An anchor 6 is provided on the web tensioning hole 5.

[0039] Furthermore, the base plate, left side plate, right side plate, and front plate are all made of steel.

[0040] Furthermore, the top of the tensioning groove steel mold 1 is higher than the top elevation of the box girder concrete.

[0041] Furthermore, a circular metal corrugated pipe is pre-embedded in the web tensioning hole 5.

[0042] Furthermore, an anchor plate 7 is provided between the web tensioning hole 5 and the anchor 6.

[0043] Furthermore, the anchor plate 7 has grouting holes on its edge.

[0044] Furthermore, the base plate, left side plate, right side plate, and front plate are all coated with a release agent.

[0045] Furthermore, the gaps in the comb-shaped groove 2 are filled with foam adhesive.

[0046] Furthermore, the gaps between the reserved hole 4 and the web tensioning hole 5 are sealed with foam adhesive.

[0047] Specifically:

[0048] Tensioning channel steel mold 1: The tensioning channel is mainly composed of four steel plates assembled into a triangular prism box structure, namely the bottom plate, left and right side plates, and web plate, which improves the overall performance and stability. The top plate of the box girder is not easily deformed during the concrete pouring process, and the appearance quality after demolding is better.

[0049] Comb-shaped groove 2: Located on the side plate of the tensioning channel steel formwork, it is opened at equal intervals according to the spacing of the reinforcing bars in the design drawings. The left and right side plates are provided with comb-shaped grooves to facilitate the installation of reinforcing bars and the disassembly of the formwork.

[0050] 3. Flat metal corrugated pipe: For box girder top slabs with transverse prestressed tensioning system design, flat metal corrugated pipes need to be pre-embedded at certain intervals to facilitate the smooth progress of subsequent steel strand bundle installation, tensioning and anchoring work.

[0051] Reserved hole 4: Located on the side plate steel mold, the hole is opened on the side plate of the steel mold according to the design position of the prestressed tensioning tendon, so that the steel strand can pass through laterally, and a certain length of joint is reserved inside the slot for later restoration of the corrugated pipe at the slot.

[0052] Web tensioning hole 5: Located at the tensioning part of the web steel strand bundle, a pre-embedded circular metal corrugated pipe is used to facilitate longitudinal tensioning of the web.

[0053] Anchor 6: It can play the role of anchoring and is a permanent anchoring device. In tension groove concrete structures, it can transfer the tensile force to the interior and is also known as a prestressed anchor.

[0054] Anchor plate 7: The upper part has grouting holes. Its strength must meet the compressive stress requirements during prestressing tensioning construction, so as to transmit pressure and distribute the force evenly.

[0055] II. A construction method for a combined steel formwork for web tensioning grooves

[0056] Based on the same inventive concept, this application also provides a construction method for a web tensioning groove combined steel formwork, which, based on the web tensioning groove combined steel formwork structure described above, includes the following steps:

[0057] S1. Operation preparation: Lay out the size and position of the tensioning groove at the top plate and web of the box girder according to the design location, and make a steel mold according to the layout size. The spacing of the comb-shaped groove is cut according to the spacing of the reinforcing bars.

[0058] S2. After applying release agent to the assembled steel mold, install it at the tensioning slot and adjust its height so that the top of the steel mold is slightly higher than the designed top elevation H of the box girder concrete to prevent concrete from flowing into the slot during the concrete pouring process.

[0059] S3, install the anchor plate and anchorage of the web tensioning hole in sequence, the transverse flat metal corrugated pipe and the steel bar, but pay attention to the requirement that the lap length of the steel bar must meet the requirements when reinforcing welding;

[0060] S4, cut off the corrugated pipe inside the tensioning groove, leave a certain length of joint a on both sides, cut the steel bar inside the tensioning groove in the middle, and bend it vertically upward about 135° to ensure the tensioning operation space;

[0061] S5, using the intelligent tensioning method: The jacks are placed in the tensioning groove, and the longitudinal steel strands in the web are tensioned first. The prestressed steel strands are high-strength, low-relaxation steel strands with a tensile strength standard value of fpk = Φs15.2. After the web tensioning is completed, grouting and anchoring are carried out promptly, followed by curing.

[0062] S6. After the anchor is sealed, restore the corrugated pipe at the cut-off point and seal the joint tightly to prevent concrete slurry from entering and affecting the later tensioning. Then install the transverse prestressed steel strands of the top plate, with the same specifications and models as above.

[0063] S7, restore the steel bars inside the tensioning groove to the horizontal lap position, and reinforce the lap joint with full welding on one side, with the weld length satisfying L≥10d (d is the diameter of the steel bar);

[0064] After the steel mesh inside the tensioning channel is welded and reinforced, the tensioning channel concrete is poured and compacted with a manual immersion vibrator. When used again, the steel mold can be reassembled.

[0065] Specific implementation plan:

[0066] First, based on the groove size and the design drawings of the reserved reinforcing bars and corrugated pipes in the groove, make a steel mold for the web tensioning groove, reserve the corrugated pipe holes and the comb-shaped joint through which the reinforcing bars pass, and brush a release agent on the surface of the steel mold before use.

[0067] Then, during the concrete pouring process of the box girder, foam adhesive is used to fill the gaps in the comb-shaped grooves of the steel mold to prevent grout leakage.

[0068] Furthermore, when the transverse corrugated pipe and reinforcing bars pass through the tensioning slot, they are installed in sequence according to the design spacing and position. The corrugated pipe is cut off at the tensioning slot, and the steel strands are then threaded through. The corrugated pipe at the cut-off point is restored, and foam glue is used to seal the joint to ensure smooth grouting and anchoring later.

[0069] Furthermore, since the transverse prestressing of the box girder top slab is tensioned last, the subsequent threading of steel strands ensures sufficient space for web tensioning without affecting the smooth tensioning in the later stages.

[0070] Furthermore, when the reinforcing bars pass through the tensioning slot, the transverse ordinary reinforcing bars are first cut off, and the ends of the reinforcing bars passing through the comb-shaped slot are bent upwards by about 135° to ensure tensioning operation space. At the same time, it is important to ensure that the welding of the reinforcing bar ends meets the requirement that the single-sided weld length L is not less than 10d. Compared with the traditional method of cutting off the entire length of the reinforcing bars in the tensioning slot, this can reduce one weld, save time, and improve efficiency and quality.

[0071] Furthermore, after tensioning, the combined steel mold of the tensioning slot is removed in sequence, and the bent ends of the reinforcing bars on both sides of the tensioning slot are straightened and welded to ensure the quality of the reinforcing bars at the tensioning slot. Finally, concrete is poured and vibrated to compact it, and curing is carried out. If reuse is required, it can be reassembled.

[0072] In summary:

[0073] 1. This application eliminates the need to chisel away the concrete around the tensioning channel to expose the reinforcing bars, thus avoiding damage to the structure of the tensioning channel, ensuring the welding length of the reinforcing bars, saving labor time and costs, and improving efficiency and reinforcement quality.

[0074] 2. This application can solve the complex construction problem caused by the construction of steel bars, corrugated pipes, steel strands, etc. at the tensioning groove, and avoid the conflict between various components at the groove opening while ensuring the operating space for web tensioning.

[0075] 3. Compared with wooden formwork, the combined steel formwork of this application improves the overall performance and stability, is easy to install and dismantle before and after construction, does not affect the construction of each process, and is conducive to the turnover and reuse of materials;

[0076] 4. During the box girder casting process, foam adhesive was used to seal the comb-shaped grooves and corrugated pipe joints on the steel plate to prevent grout leakage, ensure the tensioning groove structure and facilitate demolding, and further improve the construction technology level of the tensioning groove.

[0077] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of constructing a web tension slot composite steel form structure, characterized by: The combined steel mold structure for the web tensioning groove is located at the opening of the tensioning groove, including a tensioning groove steel mold (1) with a triangular prism-shaped box structure. The tensioning groove steel mold (1) is composed of a bottom plate, a left side plate, a right side plate, and a front plate. The left side plate and the right side plate are provided with comb-shaped grooves (2) with equal spacing. The comb-shaped grooves (2) are provided with reinforcing bars (9). The left side plate and the right side plate are provided with reserved holes (4) in the middle. The reserved holes (4) are pre-embedded with flat metal corrugated pipes (3). The flat metal corrugated pipes (3) are provided with transverse steel strands. The front plate is provided with a web tensioning hole (5) in the middle. The web tensioning hole (5) is provided with longitudinal steel strands. The web tensioning hole (5) is provided with an anchor (6). The construction method includes the following steps: S1. Operation preparation: Lay out the size and position of the tensioning groove at the top plate and web of the box girder according to the preset location, and make the tensioning groove steel mold according to the laid-out size, and open the comb-shaped groove according to the spacing of the reinforcing bars. S2. After applying release agent to the assembled tensioning groove steel mold, install it at the tensioning groove opening and adjust the height so that the top of the steel mold is higher than the preset top elevation H of the box girder concrete. S3, install the anchor plate and anchorage of the web tensioning hole in sequence, and the transverse flat metal corrugated pipe and steel bar; S4, cut off the corrugated pipe inside the tensioning groove, leave a pre-set length of joint on both sides, and cut the steel bar inside the tensioning groove in the middle and bend it vertically upward at about 135°. S5, place the jack into the tensioning groove, first tension the longitudinal steel strand bundles at the web, the longitudinal prestressed steel strands are steel strands with a tensile strength of fpk=Φs15.2, after the web tensioning is completed, grouting and anchoring are carried out in time, and then curing is performed. S6. After the anchor is sealed, restore the corrugated pipe at the cut-off point and seal the joint tightly. Then install the transverse prestressed steel strands of the top plate. The transverse prestressed steel strands also use steel strands with a tensile strength of fpk=Φs15.

2. S7, restore the steel bars inside the tensioning groove to the horizontal lap position, and reinforce the lap joint with full welding on one side, with a weld length L≥10d, where d is the diameter of the steel bar; After the steel mesh inside the tensioning channel is welded and reinforced, the tensioning channel concrete is poured and compacted using a manual immersion vibrator.

2. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: The base plate, left side plate, right side plate, and front plate are all made of steel.

3. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: The top of the tensioning groove steel mold (1) is higher than the top elevation of the box girder concrete.

4. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: A circular metal corrugated pipe is pre-embedded in the web tensioning hole (5).

5. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: An anchor plate (7) is provided between the web tensioning hole (5) and the anchor (6).

6. The construction method of a web tensioning groove combined steel formwork structure according to claim 5, characterized in that: The anchor plate (7) has grouting holes on its edge.

7. The construction method of a web tension groove combined steel form structure according to claim 2, characterized in that: The base plate, left side plate, right side plate, and front plate are all coated with a release agent.

8. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: The gaps in the comb groove (2) are filled with foam adhesive.

9. The construction method of a web tension groove combined steel form structure according to claim 1, characterized in that: The gaps between the reserved hole (4) and the web tensioning hole (5) are filled with foam sealant.

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