CN111501517A - Novel external prestressed assembly of prestressed box girder - Google Patents
Novel external prestressed assembly of prestressed box girder Download PDFInfo
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- CN111501517A CN111501517A CN202010288060.3A CN202010288060A CN111501517A CN 111501517 A CN111501517 A CN 111501517A CN 202010288060 A CN202010288060 A CN 202010288060A CN 111501517 A CN111501517 A CN 111501517A
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- box girder
- prestressed
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D2/00—Bridges characterised by the cross-section of their bearing spanning structure
- E01D2/04—Bridges characterised by the cross-section of their bearing spanning structure of the box-girder type
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D21/00—Methods or apparatus specially adapted for erecting or assembling bridges
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D2101/00—Material constitution of bridges
- E01D2101/20—Concrete, stone or stone-like material
- E01D2101/24—Concrete
- E01D2101/26—Concrete reinforced
- E01D2101/28—Concrete reinforced prestressed
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- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Bridges Or Land Bridges (AREA)
Abstract
The invention provides a novel external prestressed assembly of a prestressed box girder, which comprises an external cable and an anchoring system, and is characterized in that: the external cable comprises a main casing, a plurality of small casings arranged in the main casing, a plurality of steel strands arranged in the small casings and twisted with each other, cement paste filled between the main casing and the small casings, and grease filled between the small casings and the steel strands. The external prestressed assembly of the prestressed box girder can realize multiple corrosion prevention of the external steel strand and is convenient for later cable replacement, and has good popularization and practical values.
Description
Technical Field
The invention belongs to the technical field of bridge construction, and particularly relates to a novel external prestressed assembly of a prestressed box girder.
Background
With the continuous improvement of bridge construction technology, the application of the external prestressed tendons of the bridge is applied more and more in the construction process of modern bridges. The external prestress structure has the characteristics of flexible arrangement, safety, reliability and convenience in construction and replacement, can greatly and effectively improve the bearing capacity of the bridge, particularly realizes cable adjustment and cable replacement under the condition that the structure can normally work, and has the advantage which is incomparable with other reinforcement modes. However, the external prestressed tendons are not wrapped in concrete, so that the external prestressed tendons are extremely easily influenced by adverse environments, and are particularly sensitive to fire and corrosive chemicals. When the bridge is in an environment with extremely strong corrosivity, the corrosion prevention of the external bundle steel strand is the important factor of the external bundle design, and the service life of the external bundle or the bridge structure can be directly related.
Disclosure of Invention
Aiming at the problems, the invention provides a novel external prestressed assembly of a prestressed box girder, which can realize multiple corrosion prevention of an external steel strand and is convenient for cable replacement in the later period.
The invention is realized by the following technical scheme.
The utility model provides a novel external prestressing force subassembly of prestressing force box girder, includes external cable, anchor system, its characterized in that: the external cable comprises a main casing, a plurality of small casings arranged in the main casing, a plurality of steel strands arranged in the small casings and twisted with each other, cement paste filled between the main casing and the small casings, and grease filled between the small casings and the steel strands.
As a specific technical scheme, the anchoring system comprises a protective cover, an anchor plate pad, a pre-buried pipe, a connecting cylinder, a spiral rib and a clamping piece, wherein the protective cover, the anchor plate pad, the pre-buried pipe and the connecting cylinder are sequentially connected, the spiral rib is arranged on the outer side of the anchor plate, and the clamping piece is arranged in a reserved steel strand penetrating hole of the anchor plate.
As a specific technical scheme, a wax injection hole is reserved in the anchor plate pad, and an exhaust hole is formed in the pre-buried pipe.
As a specific technical scheme, the upper part of the connecting cylinder is provided with an exhaust hole, and the lower part of the connecting cylinder is provided with a grouting hole.
As a specific technical scheme, the protective cover is connected with the anchor plate through bolts.
As a specific technical scheme, a sealing device is arranged between the embedded pipe and the connecting cylinder.
As a specific technical scheme, the main sleeve is fixedly connected with the connecting cylinder through a hoop.
As a specific technical scheme, a sealing tape is arranged at the joint seam of the connecting cylinder and the main sleeve.
As a specific technical scheme, the total sleeve is an HDPE pipe with the diameter of 80-150 mm.
As a specific technical scheme, the small sleeve is a PE pipe.
The invention has the beneficial effects that:
1. the external prestressed cable adopts the unbonded common steel stranded wire, can realize quadruple corrosion resistance, and has low cost investment compared with the unbonded epoxy steel stranded wire and the unbonded galvanized steel stranded wire.
2. The invention separates the anchoring end from the free end. The anchoring end is short in length, wax injection is adopted for corrosion prevention, the free end of the body cable is long, and cement slurry injection is adopted for corrosion prevention; the most economical anti-corrosion measures are adopted for different parts, and the purpose of replacing a single steel strand can be realized.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a cross-sectional view of an extra-corporeal cable according to the present invention;
FIG. 3 is a schematic illustration of the present invention after installation;
FIG. 4 is a schematic view of a combination of a small sleeve, a steel strand and grease in an outer cable;
the meanings of the marks in the above figures are as follows:
1-external cable, 101-total casing, 102-small casing, 103-steel strand, 104-cement paste, 105-grease;
2-anchoring system, 201-protective cover, 202-anchor plate, 203-anchor plate pad, 204-pre-buried pipe, 205-connecting cylinder, 2051-vent hole, 2052-grouting hole, 206 spiral rib, 207-clip, 208-sealing device;
3-hoop holding;
4-sealing tape;
5-oily wax;
6-cement slurry;
7-a steering gear.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Examples
A novel external prestressed assembly of a prestressed box girder, please refer to fig. 1 to 4, comprising an external cable 1 and an anchoring system 2; the external cable 1 comprises a main casing 101, a plurality of small casings 102 arranged in the main casing 101, a plurality of steel strands 103 arranged in the small casings 102 and twisted with each other, cement slurry 104 filled between the main casing 101 and the small casings 102, and grease 105 filled between the small casings 102 and the steel strands 103; in the structure, grease 105, small casing pipes 102, cement slurry 104 and a main casing pipe 101 form a quadruple anti-corrosion structure for the steel strand 103; the steel strand 103, the grease 105 and the small sleeve 102 form an unbonded prestressed steel strand.
Further, in a preferred embodiment, referring to fig. 1 and fig. 3, the anchoring system 2 includes a protective cover 201, an anchor plate 202, an anchor plate pad 203, an embedded pipe 204, a connecting cylinder 205, a spiral rib 206 disposed outside the anchor plate 203, and a clamping piece 207 disposed in a hole through which a steel strand passes, which are reserved in the anchor plate 202; wherein, the anchor plate 202 is reserved with steel strand through holes, and the number of the holes is consistent with the number of the designed steel bundles; the clamping piece 207 is used for anchoring the steel strand in the steel strand tensioning process; the pre-buried pipe 204 is pre-buried in the concrete at the anchoring end of the box girder and forms a transition section channel with the connecting cylinder 205.
Further, in a preferred embodiment, referring to fig. 1 and fig. 3, a wax injection hole 2031 is reserved in the anchor plate pad 203 for wax injection and corrosion prevention at the anchoring end after tensioning is completed; the pre-buried pipe 204 is provided with an exhaust hole 2051 for exhausting in the wax injection process of the anchoring section.
Further, in a preferred embodiment, referring to fig. 1 and 3, the connecting cylinder 205 is provided with an exhaust hole 2051 at the upper part thereof for exhausting air in the anchoring section wax injection process; the lower part of the connecting cylinder 205 is provided with a grouting hole 2052 for injecting cement slurry after tensioning is finished.
Further, in a preferred embodiment, referring to fig. 1 and 3, the protective cover 201 is bolted to the anchor plate 202.
Further, in a preferred embodiment, referring to fig. 3, the external prestressed assembly for prestressed box girders according to the present invention further includes a deflector 7 and a damper; the steering gear 7 is in a cluster type, is embedded in concrete connected with the box body and is used for steering in an external cluster mode; the shock absorber is used for reducing the vibration of the free end of the external cable in the later bridge operation process.
Further, in a preferred embodiment, referring to fig. 1 and 3, a sealing device 208 is arranged between the embedded pipe 204 and the connecting cylinder 205 for isolating the wax injection corrosion prevention at the anchoring end and the grouting corrosion prevention at the free end.
Further, in a preferred embodiment, referring to fig. 1 and 3, the general casing 101 is connected and fixed with the connecting cylinder 205 through the hoop 3.
Further, in a preferred embodiment, referring to fig. 1 and 3, a sealing tape 4 is disposed at the joint seam of the connecting cylinder 205 and the overall sleeve 101.
Further, in a preferred embodiment, the overall casing 101 is an HDPE pipe having a diameter of 80 to 150 mm.
Further, in a preferred embodiment, the small sleeve 102 is a PE tube.
The installation and construction method of the invention is as follows:
1) HDPE pipe welding and installation
Welding: and welding the HDPE pipes by using a hot-melt tool. Before welding the HDPE pipes, the pipes are placed in a clamping device and clamped, and the welded end faces of the two pipes are flattened by a parallel motor-driven rotary cutter under the action of pressure. And the two end faces meet the requirement of flatness when contacting with each other.
Installation: before the HDPE pipe is installed, sundries in the steering gear are cleaned, and then the HDPE pipe penetrates through the steering gear.
2) Unbonded prestressed steel strand pulling bundle
Blanking of the unbonded prestressed steel strand: and (4) carrying out steel strand blanking according to a design drawing, wherein the blanking length of the steel strand is the stretching working length of two ends. And cutting the steel strand by using a grinding wheel cutting machine.
Unbonded prestressed steel strand pulling bundle
a) Numbering the steel strands which are fed well, and straightening one by one to prevent winding;
b) binding the straightened steel strand once every 1m by adopting a thin iron wire;
c) cleaning the pipeline by using a beam penetrating machine before penetrating the beam to ensure that the pipeline is smooth and has no water or other impurities;
d) the steel strands are matched by a strand pulling machine;
e) one end of the prestressed tendon is tied up by an adhesive tape during the tendon penetration, so that the tendon penetration is convenient, and the pipeline is prevented from being scratched during the tendon penetration.
f) When the steel strand is pulled back and forth, the steel strand cannot be twisted, and the steel strand is ensured to be straight.
g) After the steel strand is threaded, the working length of the steel strand at two ends is not less than the designed value.
3) Tensioning equipment installation and steel strand tensioning
a) Tensioning device installation
The installation sequence of the tensioning equipment from inside to outside is as follows: anchor backing plate, work anchor, work clamping piece, limiting plate, jack, instrument anchor, instrument clamping piece. After the penetration is finished, the anchor backing plate is cleaned, and the working anchor is installed in the anchor backing plate groove, so that the working anchor and the anchor backing plate are kept vertically and tightly attached together. The clamping piece is pushed into a taper hole of the working anchor along the steel strand until the clamping piece is pushed by hands until the clamping piece is not moved, and then the clamping piece is tamped by a steel pipe. The clip fits flush. The jack is installed and connected with the oil pump, and the tool anchor clamping piece are installed.
b) Stretching of steel strand
The steel strand is stretched symmetrically at two ends simultaneously. And (3) starting external bundle tensioning construction after the single box girder of the main bridge is completely folded, wherein the tensioning sequence of the steel strands is that the steel strands are tensioned and elongated first and then tensioned to form short bundles, and two ends of the steel strands are symmetrically tensioned. The prestress tensioning is carried out in two stages, the first stage is pretensioning, and the tensioning force is 10% of the designed prestress; and grouting the pipeline after the pre-tensioning is finished, and performing the second-stage prestress tensioning after the cement paste reaches the designed strength. The second stage of tensioning is carried out in three stages: 15%, 30% and 100%, and keeping the load for 5 minutes after each stage of tensioning is finished, and making tensioning records. The stretching process adopts dual standard control of mainly stretching force and secondarily stretching amount, and the deviation between the actual stretching amount and the theoretical stretching amount is not more than +/-6 percent in the stretching process. And when the tension is stretched to the design value, the load is kept for 5 minutes, and the actual elongation value is within the allowable deviation range, so that oil is slowly returned, anchored and jacked.
4) Grouting and mounting protective cover
a) Temporary tool installation protective cover
And after tensioning is finished, cutting redundant steel strands outside the anchor plate by using a portable abrasive wheel cutting machine, and controlling the reserved length according to a design drawing. And (3) coating a layer of grease foam on the inner wall of the tool protective cover, installing a temporary protective cover, taking down after wax injection and solidification, and installing a permanent protective cover.
b) Grouting
And blowing impurities in the holes by using an air compressor, and putting water and additives and then cement into the slurry mixer according to the sequence of putting the water and the additives. The grouting sequence is from bottom to top. And starting a grouting pump, when the slurry output by the grouting pump reaches the required consistency, grouting, and keeping the grouting pump continuously working in the grouting process.
c) Permanent protective cover for installation
And after the pore canal is grouted and reaches the strength, performing second-stage tensioning, performing anticorrosion treatment on the prestressed anchor head after tensioning is finished, smearing grease on the steel strand again for anticorrosion, injecting wax, and installing a permanent protective cover.
d) Oil-impregnated wax
The oily wax is injected in two parts. One part is used for anchoring the system anchor backing plate to the sealing plate, and the other part is used in the protective cover. And constructing the oily wax by adopting a hot melting wax injection machine.
5) Shock absorber mounting
The external prestress system vibration absorber is mainly used for fixing an external beam and reducing the vibration of the external beam of the body under the action of dynamic load. The shock absorber is connected with the bridge body into a whole through the embedded bolt. And the fastening of the external beam is realized by screwing the nut.
Claims (10)
1. The utility model provides a novel external prestressing force subassembly of prestressing force box girder, includes external cable (1), anchor system (2), its characterized in that:
the external cable (1) comprises a main casing (101), a plurality of small casings (102) arranged in the main casing (101), a plurality of steel strands (103) arranged in the small casings (102) and twisted with each other, cement paste (104) filled between the main casing (101) and the small casings (102), and grease (105) filled between the small casings (102) and the steel strands (103).
2. The novel external prestressed assembly of prestressed box girder according to claim 1, wherein said anchoring system (2) comprises a protective cover (201), an anchor plate (202), an anchor plate pad (203), a pre-embedded pipe (204), a connecting cylinder (205) connected in sequence, a spiral rib (206) disposed on the outer side of the anchor plate (203), and a clamping piece (207) disposed in the hole through which the steel strand passes reserved in the anchor plate (202).
3. The novel prestressed box girder external prestressing assembly of claim 2, wherein a wax injection hole (2031) is reserved in the anchor pad (203), and the embedded pipe (204) is provided with an exhaust hole (2051).
4. The novel prestressed box girder external prestressing assembly according to claim 2, wherein the connecting cylinder (205) is provided with an exhaust hole (2051) at the upper part and a grouting hole (2052) at the lower part.
5. A novel prestressed box girder external prestressing assembly according to claim 2, wherein said protecting cover (201) is bolted to the anchor plate (202).
6. A novel prestressed box girder external prestressing assembly according to claim 2, wherein a sealing device (208) is provided between the embedded pipe (204) and the connecting cylinder (205).
7. The novel external prestressed assembly of prestressed box girder according to claim 2, wherein said main casing (101) is fixedly connected to said connecting tube (205) by means of anchor ear (3).
8. A novel prestressed box girder external prestressing assembly according to claim 2, wherein the joint of the connecting cylinder (205) and the main bushing (101) is provided with a sealing tape (4).
9. A novel prestressed box girder external prestressing assembly according to claim 1, wherein said overall pipe (101) is a HDPE pipe with a diameter of 80-150 mm.
10. A novel prestressed box girder external prestressing assembly according to any one of claims 1 to 9, wherein said small sleeve (102) is a PE pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010288060.3A CN111501517A (en) | 2020-04-13 | 2020-04-13 | Novel external prestressed assembly of prestressed box girder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010288060.3A CN111501517A (en) | 2020-04-13 | 2020-04-13 | Novel external prestressed assembly of prestressed box girder |
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| CN111501517A true CN111501517A (en) | 2020-08-07 |
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| CN202010288060.3A Pending CN111501517A (en) | 2020-04-13 | 2020-04-13 | Novel external prestressed assembly of prestressed box girder |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113931084A (en) * | 2021-10-08 | 2022-01-14 | 新疆交通建设集团股份有限公司 | Construction method for external prestress of steel-concrete composite beam |
| CN114855617A (en) * | 2022-04-18 | 2022-08-05 | 中交二公局东萌工程有限公司 | External prestress construction method for newly-built variable-cross-section continuous beam bridge |
| CN114855629A (en) * | 2022-05-23 | 2022-08-05 | 中建八局西北建设有限公司 | Grouting construction method for pore canal without exhaust hole of prestressed bridge |
-
2020
- 2020-04-13 CN CN202010288060.3A patent/CN111501517A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113931084A (en) * | 2021-10-08 | 2022-01-14 | 新疆交通建设集团股份有限公司 | Construction method for external prestress of steel-concrete composite beam |
| CN114855617A (en) * | 2022-04-18 | 2022-08-05 | 中交二公局东萌工程有限公司 | External prestress construction method for newly-built variable-cross-section continuous beam bridge |
| CN114855629A (en) * | 2022-05-23 | 2022-08-05 | 中建八局西北建设有限公司 | Grouting construction method for pore canal without exhaust hole of prestressed bridge |
| CN114855629B (en) * | 2022-05-23 | 2024-03-15 | 中建八局西北建设有限公司 | Grouting construction method for pore canal without vent hole of prestressed bridge |
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