CN103938533B - The construction method of Simply supported non-uniform structure - Google Patents

Abstract

The invention discloses a construction method for a simply supported variable continuous structure. A bridge pier is poured, and an inverted T-shaped cover beam is poured on the top of the bridge pier; a support is installed on the wing plate of the inverted T-shaped cover beam; The hoisting of the box girder is placed on the support; above the inverted T-shaped cover beam, the beam end top plate of the small box girder resting on the same inverted T-shaped cover beam is bound and connected to the reinforcement cage, and the negative moment is set at the same time The corrugated steel beams are threaded through the beams; concrete is poured above the inverted T-shaped cover beam, the negative moment steel beams are stretched and grouted, so that the steel cages form the cast-in-place concrete connection parts of the reinforced concrete structure, and the entire simply supported substation is completed. Connections of continuous structures. The invention has the advantages of reliable structure and good durability of common simply supported variable continuous structure, and can also improve the bridge landscape, greatly reduce the structural height from the bridge deck to the bottom of the girder, save the clearance under the bridge, and simplify the construction steps , a simple-supported variable-continuous structure with shortened construction period and its construction method.

Description

Construction method of simply supported variable continuous structure

technical field

The invention relates to the technical field of bridge structure and construction, in particular to a construction method of a simply supported variable continuous structure.

Background technique

The simply supported beam structure system with continuous bridge deck is often at a disadvantage in the competition with the continuous beam structure system due to the disadvantages of easy cracking of the bridge deck. At the same time, due to the complex and cumbersome construction of cast-in-place concrete continuous beams, people have always hoped to combine the batch prefabrication of simply supported beams with the superior performance of continuous beams, and to speed up the construction of continuous beams by means of mass prefabrication of beams or slabs. The cumbersome formwork process is omitted, resulting in the "simply supported first and then continuous" construction method of prefabricating the entire span beam and slab, erecting it in place, pouring concrete at the end and stretching the prestress to make it continuous. The system is called "simply supported first and then continuous structural system". At present, the simple-supported-to-continuous structure accounts for a large proportion of the porous medium-span bridges in the bridges of high-grade highways (especially expressways).

Combining the two structural systems of continuous bridge deck and simply supported variable continuous structure, the comparison of the advantages and disadvantages of the schemes is shown in the following table:

It can be seen from the above table that the simply supported variable continuous structure system is slightly inferior to the bridge deck continuous scheme in terms of construction speed and project cost, and is superior to bridge decks in terms of structural stiffness, durability, bridge landscape, and engineering applications. Continuity program. The bridge on the expressway is a road section with many heavy vehicles, which has higher requirements on the reliability and durability of the structure. To sum up, the simply supported variable continuous small box girder is a better structural solution.

The construction process of the common simply supported variable continuous structure is generally simple supported first and then continuous bridge construction. The specific process is as follows:

① The prefabrication of the main girder adopts factory production. When the concrete strength of the girder and slab reaches 100% of the design strength, the prestressed steel strands in the positive bending moment area are stretched, and the tunnel grouting is performed after the stretching is completed.

②Before the steel strands in the negative bending moment area are stretched, set up temporary supports, and install the beams and slabs on the temporary supports hole by hole to make it a simply supported state, and install the permanent supports in place at the same time.

③ Connect the steel bars in the joint section, set the joint steel bundle bellows and pass the steel strands in the bellows, and pour concrete when the daily temperature is ≤ 15°C. When the strength of the concrete reaches 100% of the design strength, the strands in the negative bending moment area are stretched and grouted.

④Remove the temporary support to complete the transition from simple support to continuous system.

The simply supported variable continuous structure formed according to the above process has the following advantages:

①It has the advantages of high rigidity, small deformation, less expansion joints, comfortable driving, and good structural durability.

②The prestressed steel tendons of simply supported beams are stretched in the factory, while the layout and tension of prestressed steel tendons in the negative moment area are all carried out on the main beam. Only hoisting equipment is needed to lift the main beam, which reduces construction equipment and It can avoid obstacles on the ground caused by tensioning the prestressed steel strands.

③Prefabricated beams can use standard components for factory unified production and management, which is beneficial to technical operations, saves construction time, shortens the construction period, and improves economic benefits.

The currently applied small box girder simply supported variable continuous structure system has obvious advantages in terms of structural rigidity, durability, and engineering application, but there are also problems such as excessive cover beam height and relatively long construction period. The conventional simply supported variable continuous structure still has the following deficiencies:

① It is necessary to design a large cover beam. If a rectangular cover beam is used, the calculated cover beam height will be about 3.8m. In order to meet the clearance under the bridge, the scheme requires the bridge deck elevation to be raised by about 2m; moreover, the cover beam is bulky and oppressive. Strong sense, poor landscape effect.

② Generally, the system conversion of the support is required, and the construction is relatively troublesome.

③ The workload of steel bar binding and concrete pouring of the beam is relatively large, which will cause the extension of the construction period.

4. There is also another kind of uncapped beam on the top of the pier, the prefabricated small box girder is first supported on the temporary support, and the method of removing the support after the beam (under the support) is poured. However, this construction method has high requirements for the stability of the support, and the construction and removal of the temporary support is labor-intensive and material-intensive. The construction will also seriously affect the traffic.

Therefore, for the current simply supported variable continuous structure and its construction method, it is necessary to carry out research and improvement for further optimization. Those skilled in the art have been devoting themselves to the development of a simply supported variable continuous structure and its construction method, which can overcome the above-mentioned shortcomings, not only have the advantages of common simple supported variable continuous structures such as reliable structure and good durability, but also improve the bridge landscape, The height of the structure from the bridge deck to the bottom of the cap beam is greatly reduced, the clearance under the bridge is saved, the construction steps are simplified, and the construction period is shortened.

Contents of the invention

In view of the deficiencies of the above-mentioned prior art, the present invention proposes a simple-supported variable continuous structure that has the advantages of reliable structure and good durability, and can also improve the bridge landscape and greatly reduce the structural height from the bridge deck to the bottom of the girder. , save the clearance under the bridge, simplify the construction steps, shorten the construction period of the simply supported variable continuous structure and its construction method.

To achieve the above object, the present invention provides a simple-supported variable-continuous structure, comprising: a bridge pier, a small box girder and a support, and the small box girder rests on the adjacent bridge piers through the support. Wherein, the simply supported variable continuous structure of the present invention also includes: an inverted T-shaped cover beam and a connection part of cast-in-situ concrete; the inverted T-shaped cover beam is arranged on the top of the pier in an inverted T shape, and the inverted T-shaped cover beam It includes wing plates and webs connected perpendicularly to each other, the wing plate of the inverted T-shaped cover beam is connected to the top of the pier, the support is arranged on the wing plate of the inverted T-shaped cover beam, and the small box The beam rests on the wing plate of the inverted T-shaped cover beam through the support; the cast-in-place concrete connection part is arranged above the web, and the two small box girders arranged on the same pier Butt joint through the cast-in-place concrete connection part.

Preferably, the top plate of the beam end of the small box girder exposes part of the internal steel bars of the beam, and the internal steel bars of the beam are connected to the connection part of the cast-in-place concrete through the integral molding of the binding steel bars and the cast-in-place concrete.

Preferably, a steel bundle bellows with negative bending moment is passed between the small box girder and the cast-in-situ concrete connection part.

Preferably, the gap between the web and the cast-in-situ concrete connection part is 50-150 mm, and the gap between the web and the small box girders on both sides is 50-150 mm.

Preferably, the upper surface of the small box girder is laid with a reinforced concrete pavement layer, a waterproof layer and an asphalt concrete pavement layer sequentially from bottom to top.

The present invention also proposes a construction method for a simply supported variable continuous structure, comprising: pouring a bridge pier, and pouring an inverted T-shaped cover beam on the top of the bridge pier; a support is installed on the wing plate of the inverted T-shaped cover beam Place the small box girder hoisting device on the support; above the inverted T-shaped cover beam, carry out the binding connection of the reinforcement cage to the beam end top plate of the small box girder placed on the same inverted T-shaped cover beam, and set Concrete is poured on the inverted T-shaped cover beam, the negative moment steel beam is stretched and grouted, so that the steel cage forms the cast-in-situ concrete connection part of the reinforced concrete structure, and the whole Connections of simply supported variable continuous structures.

Preferably, the small box girder is prefabricated in a factory to complete the tensioning and grouting of the mid-span positive bending moment steel strands. When pouring the small box girder roof, reserve Partially exposed steel bars in the beam; when binding the steel cage, bind the steel bar with the steel bar in the beam, and then post-cast together when the cast-in-place concrete connection is poured.

Preferably, a reinforced concrete pavement layer, a waterproof layer and an asphalt concrete pavement layer are successively laid on the upper surface of the small box girder from bottom to top.

The beneficial effects of simply supported variable continuous structure and construction method thereof of the present invention are as follows:

1. The structure of the present invention is reliable and durable, and the cover beam adopted by the simply supported variable continuous structure is an inverted T-shaped cover beam, which greatly reduces the structural height from the bridge deck to the bottom of the cover beam, saves the clearance under the bridge, and improves the bridge landscape, and adopt the construction method of the present invention, the construction period is short, the construction steps are simple and effective, and the labor intensity is small.

2. The top plate of the small box girder girder of the present invention exposes part of the steel bars in the beam, and realizes the integration of cast-in-place reinforced concrete with the cast-in-place concrete connection part. The structure is simple and reliable, and the workload of steel cage binding and concrete pouring is small, which shortens the construction cycle. It only needs to carry out reinforcement binding and concrete pouring on the top plate of the small box girder girder on the same pier to meet the design requirements, so the workload is small and the construction period is short.

3. The present invention does not require support conversion after the system conversion, which simplifies the construction steps.

4. In the present invention, a negative moment steel bundle bellows is pierced between the small box girder and the cast-in-situ concrete connection part, which further improves the reliability of the present invention.

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of drawings

FIG. 1 is a schematic structural diagram of the simply supported variable continuous structure of this embodiment.

FIG. 2 is a partial enlarged view of A in FIG. 1 .

Fig. 3 is a construction evolution diagram of the simply supported variable continuous structure construction method in this embodiment.

detailed description

As shown in Fig. 1 and Fig. 2, this embodiment provides a simply supported variable continuous structure, including: pier 1, small box girder 4 and support 3, small box girder 4 rests on the adjacent all through support 3 on the bridge piers. Among them, the simply supported variable continuous structure of this embodiment also includes: an inverted T-shaped cover beam 2 and a cast-in-place concrete connection part 5; Including the wing plate 21 and the web plate 22 which are vertically connected to each other, the wing plate 21 of the inverted T-shaped cover beam 2 is connected to the top of the pier 1, and the support 3 is arranged on the wing plate 21 of the inverted T-shaped cover beam 2 (that is, as shown in Fig. 2 shown on the side facing upwards of the two wings of the inverted T-shaped cover beam 2), the small box girder 4 rests on the wing plate 21 of the inverted T-shaped cover beam 2 through the support 3; the cast-in-place concrete connection part 5 is arranged on the web 22, two small box girders 4 arranged on the same pier 1 are butted through the cast-in-place concrete connection part 5.

Specifically, the partial enlarged view at A is shown in FIG. 2 . The top plate of the beam end of the small box girder 4 exposes part of the steel bars 41 in the beam, and the steel bars 41 in the beam are connected to the cast-in-place concrete connection part 5 through the integrated molding of the binding steel bars and the cast-in-place concrete. Between the small box girder 4 and the cast-in-place concrete connection part 5, there is a negative moment steel beam corrugated pipe 6, and the negative moment steel beam corrugated pipe 6 runs through the cast-in-place concrete connection part 5. Inside the roof of beam 4. In addition, as shown in Figure 2, a gap of 100mm is reserved between the web 22 and the cast-in-place concrete connection 5 (that is, when the cast-in-place concrete connection 5 is poured, it spans above the web and is in contact with the web) At the same time, a gap of 100mm is also reserved between the web 22 and the small box girders on both sides. Of course, in other specific embodiments, the specific size of the reserved gap may also be other sizes such as 50 mm or 150 mm.

As a further specific implementation of this embodiment, the upper surface of the small box girder 4 is successively laid with a reinforced concrete pavement layer, a waterproof layer and an asphalt concrete pavement layer from bottom to top. Of course, in other specific embodiments, the construction of other auxiliary facilities can also be carried out on the small box girder 4 according to the construction design needs, such as the construction of expansion joints or other construction bridge auxiliary facilities, which is a general prior art in the art. Those skilled in the art can easily construct the structure, and details will not be repeated here.

As shown in Fig. 3, the construction evolution diagram of the simply supported variable continuous structure construction method in this embodiment. The construction method of the simply supported variable continuous structure of the present embodiment is as follows:

Step 1: pouring a bridge pier 1, and pouring an inverted T-shaped cap beam 2 on top of the bridge pier.

Step 2: A support 3 is installed on the wing plate 21 of the inverted T-shaped cover beam 2; the small box girder 4 is hoisted and placed on the support 3.

Step 3: On the top of the inverted T-shaped cover beam 2, the beam end top plate 42 of the small box girder 4 resting on the same inverted T-shaped cover beam is bound and connected to the reinforcement cage, and the negative moment steel beam bellows 6 is set at the same time And wear bundles.

Step 4: Concrete is poured on the top of the inverted T-shaped cover beam 2, and the negative moment steel tendons are stretched and grouted, so that the steel cage forms the cast-in-place concrete connection part 5 of the reinforced concrete structure, and completes the construction of the entire simply supported variable continuous structure connect.

Specifically, the small box girder 4 used in the simply supported variable continuous structure construction method of this embodiment is prefabricated in factory production, and it has completed the tensioning and grouting of the positive bending moment steel tendons at the mid-span, and when pouring the top plate of the small box girder, Reserve part of the exposed beam inner steel bar 41 at the beam end top plate 42 of the small box girder 4; when performing the binding of the steel cage, tie the steel bar cage with the beam inner steel bar 41, and then connect the cast-in-place concrete Part 5 is poured together when concrete is poured. In addition, a reinforced concrete pavement layer, a waterproof layer and an asphalt concrete pavement layer are successively laid on the upper surface of the small box girder 4 from bottom to top after the pouring of the cast-in-place concrete connection portion 5 is completed.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (3)

1. A construction method of simply supported variable continuous structure, characterized in that: pouring bridge piers, and pouring an inverted T-shaped cap beam on top of said bridge piers; A support is installed on the wing plate of the inverted T-shaped cover beam; Place the hoisting of the small box girder on the support; On the top of the inverted T-shaped cover beam, the beam end top plate of the small box girder resting on the same inverted T-shaped cover beam is bound and connected to the steel cage, and the negative moment steel beam bellows is set and threaded; Concrete is poured on the top of the inverted T-shaped cover beam, and the negative moment steel tendons are stretched and grouted, so that the steel cage forms the cast-in-place concrete connection part of the reinforced concrete structure, and completes the connection of the entire simply supported variable continuous structure. 2. The construction method of simply supported variable continuous structure as claimed in claim 1, characterized in that: the small box girder is prefabricated by factory production, the tensioning and grouting of the mid-span positive bending moment steel tendons are completed, and the small box girder is poured. For the box girder roof, reserve part of the exposed beam inner reinforcement at the beam end roof of the small box girder; when binding the reinforcement cage, bind the reinforcement cage with the beam inner reinforcement, Then wait for the cast-in-place concrete connection to be poured together when the concrete is poured. 3. The construction method of simply supported variable continuous structure as claimed in claim 1, characterized in that: the upper surface of the small box girder is successively laid with reinforced concrete pavement, waterproof layer and bituminous concrete from bottom to top pavement layer.