CN211079874U

CN211079874U - Prestressed concrete beam

Info

Publication number: CN211079874U
Application number: CN201921870038.9U
Authority: CN
Inventors: 刘其伟; 罗文林; 王成明
Original assignee: Nanjing Brgtec Engineering Technology Ltd
Current assignee: Nanjing Brgtec Engineering Technology Ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-07-24
Anticipated expiration: 2029-11-01

Abstract

The utility model relates to a prestressed structure technical field discloses a prestressed concrete roof beam. The prestressed concrete beam comprises a prestressed tendon, a protective device and an anticorrosive material, wherein the prestressed tendon comprises a prestressed failure section and a prestressed effective section; the protective device comprises a protective sleeve and a spiral stirrup, the protective sleeve is sleeved on the prestress failure section, and the spiral stirrup is sleeved on the protective sleeve and a part of prestress effective section; the anticorrosive material is filled in the protective sleeve. The utility model discloses a protective casing keeps apart prestressing force inefficacy section and concrete to realize the function that prestressing force became invalid, protective casing can also act as ordinary reinforcing bar simultaneously, and play its anti effect of splitting, locate prestressing force effective segment through the spiral stirrup cover on, stride across prestressing force inefficacy section and prestressing force effective segment, strengthen the between-section crack resistance of concrete stress sudden change.

Description

Prestressed concrete beam

Technical Field

The utility model relates to a prestressed structure technical field especially relates to a prestressed concrete roof beam.

Background

In the long-term use process, transverse and oblique cracks gradually appear at the end part of the prestressed concrete hollow slab beam and the lower surface of the beam bottom, and the cracks are just positioned in the prestressed effective area and the failure area transition section of the prestressed rib. After the concrete protective layer in the cracking area is stripped, the corrosion of part of the prestressed tendons and the concrete spalling are discovered, and the corrosion of the prestressed tendons to the fracture is discovered more seriously. The reason is that the prestress failure measures of the prestress rib adopting the method of sleeving a PVC pipe on the prestress failure section at the end part of the beam have the following defects:

(1) after the prestressed tendons are tensioned, when the prestressed tendons are tensioned, stress concentration exists in the prestressed tendons in the bottom plate at the transition sections of the end prestressed effective area and the failure area, and the prestressed tendons in the prestressed failure area are isolated from the concrete by the outer sleeve PVC pipe, so that the concrete reinforcement ratio in the prestressed failure area is insufficient, and the concrete is pulled to crack;

(2) the waterproof measure of the PVC pipe sleeved outside the prestressed tendon at the prestressed failure section has defects, so that accumulated water on the bridge deck enters the PVC pipe, the prestressed tendon in the PVC pipe is corroded by the accumulated water for a long time, and finally the prestressed tendon is corroded and broken, and the concrete protective layer is cracked and damaged;

(3) the prestressed concrete hollow slab beam has two types of prestressed tendons penetrating through the end prestressed failure area, one type is artificially forced prestressed failure prestressed tendons, the other type is prestressed tendons which must keep effective prestress, after the prestressed tendons are corroded and broken due to the defects of PVC pipes and the concrete protective layer is cracked, the concrete which must keep the surface of the prestressed tendons with effective prestress is damaged and forced to crack and peel, the effectiveness of the prestress is hard to guarantee, meanwhile, the concrete in the area has cracks in large area, the durability of the prestressed tendons is reduced, finally, the two types of prestressed tendons tend to be corroded and broken, the bearing capacity of the beam body fails, and the safety of the structure is threatened.

For prestressed concrete hollow slab beams with such defects, dismantling and reconstruction are required. The method is not only a waste of resources, but also needs to interrupt traffic, and has high cost and long construction period. Particularly, if the bridge spans special structures such as railways and military facilities, the bridge is more difficult to dismantle and rebuild, higher in cost and longer in construction period.

Therefore, for newly-built prestressed concrete hollow slab bridges, reasonable and effective measures must be taken to improve the durability of prestressed tendons and the crack resistance of concrete at a prestressed failure section, and the urgent problem to be solved at present is formed.

SUMMERY OF THE UTILITY MODEL

Based on the above problem, an object of the utility model is to provide a prestressed concrete roof beam can improve the durability of prestressing force inefficacy section prestressing tendons, the anti crack performance of concrete.

In order to achieve the purpose, the utility model adopts the following technical proposal:

a prestressed concrete girder comprising:

the prestressed tendon comprises a prestressed failure section and a prestressed effective section;

the protective device comprises a protective sleeve and a spiral stirrup, the protective sleeve is sleeved on the prestress failure section, and the spiral stirrup is sleeved on the protective sleeve and part of the prestress effective section;

and the anticorrosive material is filled in the protective sleeve.

As the utility model discloses a preferred scheme of prestressed concrete roof beam, the both ends of protective casing are provided with spacing end cap, spacing end cap with protective casing forms and seals the cavity, be used for with prestressing force inefficacy section is kept apart with the concrete.

As the utility model discloses a preferred scheme of prestressed concrete roof beam, spacing end cap with the connection can be dismantled to the protective casing.

As the utility model discloses a prestressed concrete roof beam's preferred scheme, the cross-section of protective casing includes ring shape, oval ring shape or polygon.

As the utility model discloses a preferred scheme of prestressed concrete roof beam, the length of lag tube with the design length of prestressing force inefficacy section is the same.

As the preferred scheme of the prestressed concrete beam of the utility model, the spiral stirrup on the prestressed effective section is sleeved with the spiral stirrup with the length of 50cm-100 cm.

As the utility model discloses a preferred scheme of prestressed concrete roof beam, anticorrosive material includes cement base grouting material, grout or polyurethane foam.

The utility model has the advantages that:

the prestressed concrete beam provided by the utility model completely wraps the prestressed failure section in the protective sleeve, and in the subsequent concrete pouring process, the protective sleeve isolates the prestressed failure section from the concrete so as to realize the function of prestressed failure, and meanwhile, the protective sleeve can also serve as a common reinforcing steel bar and play the anti-cracking function of the common reinforcing steel bar; the spiral stirrup is sleeved on the prestress effective section, the part is open, the wrapping effect of the concrete poured subsequently on the prestress effective section is not influenced, the spiral stirrup and the protective sleeve are connected into a whole, the spiral stirrup spans the prestress failure section and the prestress effective section, and the crack resistance of the concrete stress mutation section is enhanced; and completely wrapping the prestressed failure section in the anticorrosive material to fulfill the aim of corrosion prevention of the prestressed tendon. The utility model provides a prestressed concrete roof beam, need not to change existing prestressing force hollow slab girder structure size, do not change the hollow slab girder appearance, do not change the clearance under the bridge, do not change bridge structures atress system, do not change, do not disturb existing prestressing force hollow slab girder construction process and flow, thoroughly solve hollow slab girder prestressing force inefficacy section and effective segment junctional zone concrete reinforcement rate not enough, the problem of anti-crack inefficacy, thoroughly solve hollow slab girder prestressing force inefficacy section prestressing force muscle corrosion cracked durability problem, thoroughly improved prestressing force hollow slab girder durability and life effectively, very big economic benefits has.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

Fig. 1 is a schematic view of a prestressed tendon arranged on a hollow slab beam according to an embodiment of the present invention;

fig. 2 is a schematic structural view of a tendon according to an embodiment of the present invention;

fig. 3 is a schematic structural view of a tendon and a protector according to an embodiment of the present invention;

fig. 4 is a schematic structural view of a prestressed tendon, a protective device and a limiting plug according to an embodiment of the present invention;

fig. 5 is a schematic structural view of a prestressed concrete girder according to an embodiment of the present invention;

fig. 6 is a flowchart of a method for prefabricating a prestressed concrete beam according to an embodiment of the present invention.

In the figure:

1-prestressed tendons; 2-a guard device; 3-anticorrosive material; 4-limiting plugs; 5-concrete;

11-a prestressed failure section; 12-a pre-stressed active section;

21-protective sleeve; 22-helical stirrup.

Detailed Description

In order to make the technical problems, technical solutions and technical effects achieved by the present invention more clear, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings, and obviously, the described embodiments are only some embodiments, not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to 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", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The present embodiment provides a prestressed concrete girder, which includes a tendon 1, a protector 2, and an anticorrosive material 3, as shown in fig. 1 to 5.

Specifically, the prestressed tendon 1 comprises a prestressed failure section 11 and a prestressed effective section 12; the protection device 2 comprises a protection sleeve 21 and a spiral stirrup 22, the protection sleeve 21 is sleeved on the prestress failure section 11, and the spiral stirrup 22 is sleeved on the protection sleeve 21 and a part of the prestress effective section 12; the anticorrosive material 3 is filled in the protective sleeve 21.

The prestress failure section 11 is completely wrapped in the protective sleeve 21, and in the subsequent concrete 5 pouring process, the protective sleeve 21 isolates the prestress failure section 11 from the concrete 5 so as to realize the prestress failure function, and meanwhile, the protective sleeve 21 can also serve as a common reinforcing steel bar and play a role in cracking resistance; the spiral stirrup 22 is sleeved on the prestress effective section 12, the part is open, the bond wrapping effect of the concrete 5 poured subsequently on the prestress effective section 12 is not influenced, the spiral stirrup is connected with the protective sleeve 21 into a whole, the spiral stirrup spans the prestress failure section 11 and the prestress effective section 12, and the crack resistance of the stress mutation section of the concrete 5 is enhanced; and completely wrapping the prestress failure section 11 in the anticorrosive material 3 to realize the purpose of corrosion prevention of the prestressed tendon 1.

Optionally, two ends of the protective casing 21 are provided with limiting plugs 4, and the limiting plugs 4 and the protective casing 21 form a closed chamber for isolating the prestressed failure section 11 from the concrete 5. The limiting plug 4 and the protective sleeve 21 form a closed cavity, so that the concrete 5 poured subsequently cannot enter the closed cavity, the prestress failure section 11 is isolated from the concrete 5, and the function of prestress failure is realized. Meanwhile, the prestress failure section 11 can be limited and fixed in the center of the closed cavity, so that the outer surface of the prestress failure section 11 can be uniformly wrapped in the closed cavity after the anticorrosive material 3 is injected into the closed cavity in the follow-up process, and the anticorrosive performance of the prestress failure section 11 is enhanced.

In order to facilitate later maintenance and repair, the limiting plug 4 is optionally detachably connected with the protective sleeve 21. In order to adapt to different application scenarios, the cross section of the protective casing 21 may optionally comprise a circular ring shape, an elliptical ring shape, or a polygonal shape. In this embodiment, the length of the protective sleeve 21 is the same as the design length of the prestressed failure section 11. The length of the spiral stirrup 22 sleeved on the prestress effective section 12 is 50cm-100 cm. The anticorrosive material 3 comprises cement-based grouting material, cement paste or polyurethane foam material. The material of the protective sleeve 21 may be a metal material or a non-metal material. The material of the helical stirrup 22 may be a metal material, and the outer surface thereof is specially configured (including but not limited to, notches, threads, shear keys, etc.) to enhance the adhesion between the helical stirrup 22 and the concrete 5.

In the prestressed concrete beam provided by the embodiment, the prestressed failure section 11 is completely wrapped in the protective sleeve 21, and in the subsequent process of pouring the concrete 5, the protective sleeve 21 isolates the prestressed failure section 11 from the concrete 5, so that the function of prestressed failure is realized, and meanwhile, the protective sleeve 21 can also serve as a common steel bar and play a role in cracking resistance; the spiral stirrup 22 is sleeved on the prestress effective section 12, the part is open, the bond wrapping effect of the concrete 5 poured subsequently on the prestress effective section 12 is not influenced, the spiral stirrup is connected with the protective sleeve 21 into a whole, the spiral stirrup spans the prestress failure section 11 and the prestress effective section 12, and the crack resistance of the stress mutation section of the concrete 5 is enhanced; and completely wrapping the prestress failure section 11 in the anticorrosive material 3 to realize the purpose of corrosion prevention of the prestressed tendon 1.

The prestressed concrete beam provided by the embodiment does not need to change the structural size of the existing prestressed hollow slab beam, does not change the appearance of the hollow slab beam, does not change the clearance below the bridge, does not change the stress system of the bridge structure, does not change and does not interfere with the existing construction process and flow of the prestressed hollow slab beam, thoroughly solves the problems of insufficient concrete reinforcement ratio and crack resistance failure of the boundary area of the prestressed failure section and the effective section of the hollow slab beam, thoroughly solves the durability problem of corrosion and fracture of the prestressed rib 1 of the prestressed failure section of the hollow slab beam, thoroughly and effectively improves the durability and service life of the prestressed hollow slab beam, and has great economic benefit.

The embodiment also provides a method for prefabricating the prestressed concrete beam, which is used for preparing the prestressed concrete beam. As shown in fig. 6, the method for prefabricating a prestressed concrete beam includes the steps of:

s1, mounting a protective device 2 on the prestressed tendon 1 needing forced prestressing failure, wherein a protective sleeve 21 of the protective device 2 is used for isolating the prestressing failure section 11 of the prestressed tendon 1 from the concrete 5;

s2, releasing the tension force of the prestressed tendon 1;

s3, filling the anticorrosive material 3 into the protective sleeve 21, and wrapping the prestress failure section 11;

and S4, sealing the end of the cut prestressed failure section 11.

Firstly, a protective device 2 is arranged on a prestressed tendon 1 needing forced prestressing failure, and a protective casing 21 of the protective device 2 isolates a prestressing failure section 11 of the prestressed tendon 1 from concrete 5 so as to realize the function of prestressing failure and also can serve as a common reinforcing steel bar and play a role of cracking resistance; secondly, releasing the tension force of the prestressed tendon 1, and after the prestressed tendon 1 is completely released, keeping the prestressed failure section 11 of the prestressed tendon 1 in an unstressed state and completely not participating in structural stress; then, filling the anticorrosive material 3 into the protective sleeve 21, and wrapping the prestress failure section 11 to realize the purpose of corrosion prevention of the prestress failure section 11; and finally, plugging the end part of the cut prestressed failure section 11, and improving the durability of the prestressed tendon 1 and the crack resistance of the concrete 5.

Optionally, before step S1, the method further includes the following steps: and (3) lofting and blanking the prestressed tendon 1, and determining the length and the position of the prestressed failure section 11. Firstly, lofting and blanking of the prestressed reinforcement 1 are carried out according to a construction drawing of the prestressed concrete hollow slab beam, and the length and the position of a prestressed failure section 11 of the prestressed reinforcement 1 are determined according to data in the construction drawing. Fig. 1 is a cross-sectional view of a typical hollow slab beam, fig. 2 is a top view of a tendon 1, the tendon 1 may be numbered N1, N2, N3 from top to bottom, a broken line in fig. 2 represents a prestressed failure section 11 of the tendon 1 at an end of the hollow slab beam, and a solid line represents a prestressed effective section 12 of the tendon 1. The N2 full length tendons 1 are all prestressed active sections 12 (solid line parts). Each of the N1 and N3 tendons 1 is divided into a prestressed failure section 11 (dotted line section) and a prestressed active section 12 (solid line section). The N1 and N3 tendons 1 are divided into a prestressed failure section 11 and a prestressed effective section 12, but each tendon 1 is a full-length and complete tendon. The design parameters of the prestressed failure section 11 and the prestressed effective section 12 of the N1 and N3 prestressed tendons 1 are determined by specific construction drawings, and the embodiment is only used as an example.

Optionally, after step S1 and before step S2, the method further comprises the following steps: and pouring and curing the concrete 5 are completed, and the strength index of the concrete 5 meets the design requirement. After the concrete 5 is poured and the maintenance is finished, and the strength index meets the design requirement, the tensile force of the prestressed tendon 1 is released.

The method for prefabricating the prestressed concrete beam can be used for prefabricating the prestressed concrete hollow slab beam, firstly, a protective device 2 is installed on a prestressed tendon 1 needing forced prestressing failure, and a protective casing 21 of the protective device 2 isolates a prestressing failure section 11 of the prestressed tendon 1 from concrete 5 so as to realize the function of prestressing failure and also can serve as a common steel bar and play a role in cracking resistance of the common steel bar; secondly, releasing the tension force of the prestressed tendon 1, and after the prestressed tendon 1 is completely released, keeping the prestressed failure section 11 of the prestressed tendon 1 in an unstressed state and completely not participating in structural stress; then, filling the anticorrosive material 3 into the protective sleeve 21, and wrapping the prestress failure section 11 to realize the purpose of corrosion prevention of the prestress failure section 11; and finally, plugging the end part of the cut prestressed failure section 11, and improving the durability of the prestressed tendon 1 and the crack resistance of the concrete 5.

The method for prefabricating the prestressed concrete beam provided by the embodiment does not need to change the structural size of the existing prestressed hollow slab beam, does not change the appearance of the hollow slab beam, does not change the clearance below the bridge, does not change the stress system of the bridge structure, and does not change or interfere with the existing construction process and flow of the prestressed hollow slab beam, thereby thoroughly solving the problems of insufficient concrete reinforcement ratio and crack resistance failure in the boundary area between the prestressed failure section and the effective section of the hollow slab beam, thoroughly solving the durability problem of corrosion and fracture of the prestressed rib 1 in the prestressed failure section of the hollow slab beam, thoroughly and effectively improving the durability and service life of the prestressed hollow slab beam, and having great economic benefit.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments illustrated herein, but is capable of various obvious modifications, rearrangements and substitutions without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A prestressed concrete girder, comprising:

the prestressed tendon (1) comprises a prestressed failure section (11) and a prestressed effective section (12);

the protective device (2) comprises a protective sleeve (21) and a spiral stirrup (22), the protective sleeve (21) is sleeved on the prestress failure section (11), and the spiral stirrup (22) is sleeved on the protective sleeve (21) and part of the prestress effective section (12);

and the anticorrosive material (3) is filled in the protective sleeve (21).

2. Prestressed concrete beam according to claim 1, characterized in that said protective casing (21) is provided at both ends with limiting plugs (4), said limiting plugs (4) forming a closed chamber with said protective casing (21) for isolating said prestressed failure section (11) from the concrete (5).

3. Prestressed concrete beam according to claim 2, characterized in that said limiting plugs (4) are removably connected to said protective casing (21).

4. Prestressed concrete beam according to claim 1, characterized in that the section of said protective casing (21) comprises a circular, elliptical or polygonal shape.

5. Prestressed concrete beam according to claim 1, characterized in that the length of said protective casing (21) is the same as the designed length of said prestressed failure section (11).

6. The prestressed concrete girder according to claim 1, wherein the length of the spiral stirrup (22) fitted over the prestressed effective section (12) is 50cm to 100 cm.

7. Prestressed concrete beam according to claim 1, characterized in that said anti-corrosive material (3) comprises a cement-based grouting material, a cement paste or a polyurethane foam.