CN101769042A - Matched prefabricated concrete hollow slab beam structure - Google Patents

Abstract

The invention discloses a matching prefabricated concrete hollow plate beam structure, which comprises a top plate, a web plate and a bottom plate surrounded by a plate beam structure, a hollow cavity is arranged inside the plate beam structure, and the top plate, the web plate and the bottom plate are poured with concrete As a result, shear keys are arranged on the outer surface of the web in a prefabricated manner. Therefore, the present invention adopts shear keys instead of hinge joint design, which avoids the disadvantages that the reinforcement is difficult to vibrate and compact in the narrow space of hinge joints. It also overcomes the contradiction that the stiffness of the hinge joint is smaller than that of the prestressed concrete hollow slab girder in the traditional hinge joint design, and prestresses the longitudinal and transverse bridge directions of the hollow slab beam to prevent longitudinal cracks in the bottom plate. The prevention and treatment of hinge joint disease solves the problem that there is no prevention and treatment of floor longitudinal crack disease at present.

Description

Matching precast concrete hollow slab beam structure

technical field

The invention relates to a matching prefabricated concrete hollow slab beam structure, which belongs to the field of civil engineering bridge superstructure.

Background technique

At present, there are mainly three types of damage in the upper structure of prestressed concrete hollow slab girder bridges: transverse cracks in the bottom slab, longitudinal cracks in the bottom slab, and hinge joints. For cracks and hinged joints, the deep damage mechanism is still unclear, and there has been no substantial breakthrough in prevention and control measures.

The longitudinal cracks of the bottom plate generally appear along the direction of the prestressed tendons or ordinary stressed steel bars, and once they appear, most of their lengths are greater than 1/3l, where l is the span of the beam. The current research shows that the longitudinal cracks in the bottom plate mainly have the following causes: premature tensioning of prestressed tendons, Poisson effect and radial force effect of prestressed tendons, too thin bottom plate of prestressed hollow slab beams and prestressed concrete The temperature difference between the inside and outside of the hollow slab beam. In addition, the causes of longitudinal cracks in the bottom plate are still at the qualitative analysis level, and in-depth microscopic analysis is still to be studied, and no effective prevention and control measures for longitudinal cracks in the bottom plate have been proposed.

Hinge joint disease has always been a stubborn disease of prestressed concrete hollow slab beams. As early as the 1960s, the bridge superstructure was assembled with multiple prefabricated prestressed concrete hollow slab girders. Due to the space effect, the connection between the prestressed concrete hollow slab girders was usually followed by the Soviet bridge scholar Ulitz. Therefore, in the preliminary design, the prestressed concrete hollow slab girder adopts a small hinge joint design, and the small hinge joint connection method only transmits shear force and does not transmit other internal forces. In addition, this The small hinge joints mainly have the following problems: (1) The structure is unreasonable. Compared with the overall stiffness of the hollow slab, the overall stiffness of the small hinge joints is far from that of the hollow slab, and cannot withstand the deformation and stress requirements under repeated loads; (2) The construction Difficulties The construction space for small hinge joints is very limited, which increases the difficulty of construction and cannot guarantee the compactness of the hinge joint concrete. If the side walls of the hollow slab beams are not roughened and reinforced, the small hinge joints will be damaged sooner or later matter. The design of small hinged joints has been popular for nearly 30 years. After the 1990s, it was gradually abandoned and replaced by large hinged joints. Various forms of design reinforcement for large hinged joints also emerged. On the one hand, it improved the lower flange of hollow slab girders. On the other hand, the compression flange of the hinged joint is also reinforced with steel plates or ∏-shaped reinforcement. Large hinge joints have the advantages of good integrity, high torsional rigidity, and good transverse integrity, but the appearance of large hinge joints does not mean the elimination of hinge joint defects. The phenomenon of slab stress is still common in hollow slab girder bridges. Studies have shown that the bridges with prestressed concrete hollow slab girders connected as a whole by wet joint hinges, under the action of vehicle loads, the tensile stress generated in the transverse bridge direction reaches 1.16MPa, and this stress range often acts on the hinge joints. The hinge joint is generally the joint surface of new and old concrete, and the cohesive force is relatively weak. Under repeated loads, it is easy to crack. In addition, although the upper flange of the hinge joint is under pressure, the bridge deck pavement is prone to wrapping and peeling off. and other diseases, and once the bridge deck pavement is damaged, the rainwater on the bridge deck will easily enter the pavement layer, and it is also prone to damage under the repeated action of freeze-thaw cycles and vehicle loads, which is another reason for hinge joint damage.

From the above analysis, it can be seen that the current research has not proposed effective prevention and control measures for the two diseases of floor longitudinal cracks and hinge joints, and traditional prestressed concrete hollow slab beams cannot solve these problems. Therefore, it is urgent to study a new prestressed concrete hollow slab structure, and then propose comprehensive prevention and control measures for these diseases.

Contents of the invention

The invention aims at the deficiencies of the prior art, and provides a new prestressed concrete hollow slab beam structure to prevent and control the longitudinal cracks of the bottom plate, and solves the problem that there is no effective measure for preventing and controlling the longitudinal cracks of the bottom plate.

For realizing above technical purpose, the present invention will take following technical scheme:

A matching prefabricated concrete hollow plate beam structure, comprising a top plate, a web and a bottom plate surrounding a plate beam structure, a hollow cavity is arranged inside the plate beam structure, and the top plate, web plate and bottom plate are poured with concrete, and the web Shear keys are arranged on the outer surface of the slab.

Further, the plate girder structure is provided with longitudinal prestressing tendons and transverse prestressing tendons.

Further, the positions of the transverse prestressing tendons and the longitudinal prestressing tendons are staggered.

Furthermore, the longitudinal prestressing tendons are formed by the internal bundles embedded longitudinally in the plate girder structure, while the transverse prestressing tendons are formed by the top plate transverse external bundles and the bottom plate lateral external bundles arranged on the upper and lower surfaces of the hollow cavity.

Further, the internal bundle is installed in the positioning base, and the positioning base is longitudinally arranged in the plate beam structure, and the positioning base includes a longitudinal internal bundle anchor pad and an internal bundle anchor provided on the longitudinal internal bundle anchor pad .

Further, a plurality of through holes are opened on the bottom plate.

Further, the diameter of the through hole on the bottom plate is Φ50mm˜Φ150mm.

Further, the distance between two adjacent through holes is 1m-2m.

Further, slots are provided on the outer surface of the top plate.

Further, steel bars are pre-embedded in the roof.

According to the above technical scheme, the following beneficial effects can be achieved:

1. In the hollow slab girder structure of the present invention, the shear keys are arranged on the outer surface of the web by matching prefabrication, and then the upper structure of the bridge can realize the cooperative connection of the hollow slab girder structure through the shear keys. The key replaces the hinged joint design, which avoids the disadvantages of concrete being difficult to vibrate and compact in the narrow space of the hinged joint, and also overcomes the rigidity of the hinged joint compared with that of the prestressed concrete hollow slab beam in the traditional hinged joint design. relatively minor contradictions;

2. The prestress generated by the transverse prestressed tendon offsets the transverse tensile stress generated in the entire bridge bottom plate under the action of the vehicle load, and enhances the overall function of the bridge. This not only ensures that the adjacent two prestressed concrete hollow There is compressive stress at the plate-girder matching interface, and it also ensures that the prestressed concrete hollow slab girder also has prestress in the transverse bridge direction, effectively preventing the occurrence of longitudinal cracks in the prestressed concrete hollow slab girder;

3. Through holes are set on the bottom plate to ensure that the temperature difference between the inside and outside of the prestressed concrete hollow slab beam will not be too large and the flow of air will avoid longitudinal cracks in the beam body caused by temperature stress;

4. Cutting grooves are set on the outer surface of the roof, which increases the bond between the bridge deck pavement and the structural layer, ensures the bonding between the bridge deck pavement and the prestressed concrete hollow slab beam roof, prevents the immersion of rainwater, and avoids The first protective barrier with the hinged seam failed.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Among them, through hole 1 shear key 2 internal beam anchor plate 3 internal beam anchorage 4 top plate 5 web plate 6 bottom plate 7 longitudinal internal beam 8 bottom plate horizontal external beam 9 top plate horizontal external beam 10 steel bar 11 slot 12.

Detailed ways

The accompanying drawings disclose non-restrictive structural schematic diagrams of specific embodiments involved in the present invention, and the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

The matching prefabricated concrete hollow slab girder structure of the present invention includes a top plate 5, a web 6 and a bottom plate 7 surrounding a plate girder structure, a hollow cavity is arranged in the plate girder structure, and the top plate 5, web 6 and bottom plate 7 is formed by pouring concrete, and the outer surface of the web 6 is arranged with a shear key 2 in a prefabricated manner. Therefore, the present invention adopts the shear key 2 instead of the traditional hinge joint design, that is, in the prestressed concrete hollow slab described in the present invention During the beam prefabrication process, the cast hollow slab girder structure is used as the side form of the next prefabricated hollow slab girder structure, and continues to circulate until the entire one-span hollow slab beam structure is cast; Between the slab and girder structures, the original design of large hinge joints is canceled and replaced by shear key 2, which avoids the disadvantages of reinforcement in the narrow space of hinge joints and the difficulty of vibrating and compacting concrete, and also overcomes the traditional design of hinge joints Among them, the stiffness of the hinged joint is less contradictory than that of the prestressed concrete hollow slab beam.

The analysis shows that under the first-level load of the highway, the connection of two adjacent hollow slab girder structures will have a large tensile stress in the direction of the bridge. Therefore, the shear The prestressed concrete slab girder connected by force key 2 will inevitably open under load. In this way, the overall effect of the prestressed concrete hollow slab beam will be greatly reduced, and the phenomenon of "single-slab stress" will reappear. In view of this situation, the prestressed concrete hollow slab girder prefabricated by the matching method adopts a two-way prestressing design, that is, the slab girder structure is provided with longitudinal prestressing tendons and transverse prestressing tendons, and the longitudinal prestressing tendons are embedded in the slab longitudinally The longitudinal internal bundles 8 in the beam structure are formed, while the transverse prestressed tendons are formed by the top plate lateral external bundles 10 and the bottom plate lateral external bundles 9 arranged on the upper and lower surfaces of the hollow cavity; at the same time, the transverse prestressed tendons and longitudinal prestressed The position of the ribs is wrong. Without increasing the thickness of the bottom plate 7 and fully ensuring the position of the longitudinal prestressing tendons, this increases the difficulty in the arrangement of the transverse prestressing tendons. Therefore, the transverse prestressing tendons adopt no bonding tendons outside the body, and the bottom plate lateral external beam 9 is close to the upper surface of the bottom plate 7, passes through the reserved channel at the junction of the web 6 and the bottom plate 7, and is anchored to the side beam.

In addition, the longitudinal internal bundle 8 is installed in the positioning matrix, which is longitudinally arranged in the plate girder structure, and the positioning base includes the longitudinal internal bundle anchor pad 3 and the internal body bundle arranged on the longitudinal internal bundle anchor pad 3 . Beam anchor 4.

Furthermore, studies have shown that the temperature difference between the inside and outside of the prestressed concrete hollow slab beam structure is an important reason for the longitudinal cracks in the bottom plate 7 and web 6 . Moreover, the stress on the surface of the web 6 and the bottom plate 7 is the most unfavorable under the conditions of temperature gradient and sudden cold wave. Therefore, in order to ensure that the temperature difference between the inside and outside of the prestressed concrete hollow slab beam will not be too large and the flow of air, a plurality of through holes 1 are opened on the bottom plate 7 of the prestressed concrete hollow slab beam structure, and the diameter of the opened through holes 1 is Φ50mm~ Φ150mm, and the distance between two adjacent through holes 1 is 1-2m.

An important cause of hinge joint disease in prestressed concrete hollow slab girder structures is that the deck pavement fails first. The bridge deck pavement is the first protective barrier for the hinge joint, and bears the vehicle load together with the beam body. When the bridge deck pavement is wrapped, stacked, and peeled off, the bridge deck pavement loses its role in sharing vehicle loads, and rainwater will seep into the bonding layer between the bridge deck pavement and the hollow slab girder structure along the cracks, and then penetrate into the bridge deck pavement. In the hinged joints, the hinged joints are caused. In addition, the bonding between the bridge deck pavement and the hollow slab girder structure layer is the joint surface of old and new concrete. The cutting groove 12 on the surface can strengthen the bonding effect between the bridge deck pavement and the hollow plate girder structure.

Claims (10)

1. matched prefabricated concrete hollow slab beam structure, comprise and enclose top board, web and the base plate that is connected into slab and girder, establish hollow cavity in the described slab and girder, and top board, web and base plate adopt concrete pouring to form, it is characterized in that the web external surface is arranged shear connector.

2. matched prefabricated concrete hollow slab beam structure according to claim 1 is characterized in that, slab and girder is provided with longitudinal prestressing muscle and transverse prestress muscle.

3. matched prefabricated concrete hollow slab beam structure according to claim 2 is characterized in that, transverse prestress muscle and longitudinal prestressing muscle are staggeredly located.

4. according to claim 2 or 3 described matched prefabricated concrete hollow slab beam structures, it is characterized in that, the longitudinal prestressing muscle forms by the body internal beam that vertically is embedded in the slab and girder, and then the top board weft element external beam and the base plate weft element external beam on two surfaces form the transverse prestress muscle up and down by being horizontally set at hollow cavity.

5. matched prefabricated concrete hollow slab beam structure according to claim 4, it is characterized in that, the body internal beam is installed in the matrix of location, this location matrix vertically is arranged in the slab and girder, and described location matrix comprises vertical body internal beam anchor plate and is arranged at body internal beam ground tackle on this vertical body internal beam anchor plate.

6. matched prefabricated concrete hollow slab beam structure according to claim 1 and 2 is characterized in that, offers a plurality of through holes on the base plate.

7. matched prefabricated concrete hollow slab beam structure according to claim 6 is characterized in that, the diameter range of the through hole of offering is Φ 50mm～Φ 150mm on the described base plate.

8. matched prefabricated concrete hollow slab beam structure according to claim 7 is characterized in that, the spacing between the adjacent two through hole is 1m～2m.

9. matched prefabricated concrete hollow slab beam structure according to claim 6 is characterized in that the top board external surface is offered grooving.

10. matched prefabricated concrete hollow slab beam structure according to claim 9 is characterized in that, buries reinforcing bar in the top board in advance underground.

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