CN211472128U - Continuity combination beam - Google Patents

Abstract

The utility model belongs to the technical field of bridge engineering, in particular to a continuous composite beam construction method. The problems of high internal stress of bridges in the prior art, cracks are easily generated, and service life is low, the technical solution is: including several prefabricated bridge pieces, the several prefabricated bridge pieces are connected in sequence, and the prefabricated bridge pieces are provided with prestressed bridge pieces. The prestressed tendons extend out of the cross-section of the prefabricated bridge pieces by 35-45 cm, and the prestressed tendons are connected with the prestressed tendons of the adjacent prefabricated bridge pieces in a one-to-one correspondence. The utility model divides the prestress of a span beam into a plurality of segments, the joints are not affected by the prestress, the probability of cracks is greatly reduced, and the cracks will not develop to the adjacent prefabricated bridge pieces. increased lifespan. The utility model is suitable for the construction of bridges with high requirements on traffic or construction period.

Description

A continuous composite beam

technical field

The utility model belongs to the technical field of bridge engineering, in particular to a continuous composite beam.

Background technique

Continuous beams are beams with three or more supports in construction, construction, aviation, and pipeline projects. With the rapid construction of expressways and high-speed railways, many long-span continuous girder bridges have appeared. The commonly used construction methods are hanging baskets, scaffolding, etc. The construction process is complicated and requires comprehensive pouring construction on site. A long time often becomes the limit of the entire project progress.

The domestic bridge construction is all concrete reinforced prestressed bridges, and most of the construction techniques such as hanging basket construction and full house scaffolding are used in the construction. This kind of construction technology is a common bridge construction now, which can ensure the stability of the bridge structure, and there are few cases of cracks after the construction is completed. Therefore, this construction technology should be used in China now. However, this construction technique also has many drawbacks. Such as: the construction time is very long, the frequency of machine use is too high, the service life is short, and the workload of the construction personnel is heavy.

The prefabrication assembly method is to put a large amount of concrete pouring process in the beam prefabrication field for industrial production, assemble at the project site to achieve the required prestress and internal structure, and perform a small amount of concrete pouring to realize the entire continuous beam. The main project of the entire continuous beam can be carried out in the prefabrication field, reducing the amount of on-site engineering, and can control the precision of the variable section to a higher level, which can not only improve the quality, but also greatly reduce the construction time, speed up the construction progress, and save money. A lot of engineering costs.

However, most of the existing continuous beam prefabricated assembly construction is to apply prestressing between the prefabricated bridge pieces and the already assembled bridge during assembly. The entire span of the beam is prestressed. This construction method will generate huge stress inside the bridge as a whole. Excessive stress will easily cause many cracks in the bridge deck, and the cracks will go from one segment to the adjacent segment. development, resulting in a reduction in the service life of the bridge.

Utility model content

Aiming at the problems in the prior art that the internal stress of the bridge is large, cracks are easily generated, and the service life is low, the utility model provides a continuous composite beam, the purpose of which is to divide the internal stress of the bridge into a plurality of segments, and each segment The stress is not connected, preventing the development of cracks and prolonging the service life of the bridge.

The technical scheme adopted by the utility model is as follows:

A continuous composite beam, comprising several prefabricated bridge pieces, the several prefabricated bridge pieces are connected in sequence, the prefabricated bridge pieces are provided with prestressed tendons, the prestressed tendons extend out of the cross section of the prefabricated bridge pieces by 35-35 mm. 45cm, the prestressed tendons are connected with the prestressed tendons of the adjacent prefabricated bridge pieces in one-to-one correspondence, the prestressed tendons are provided with transverse reinforcing bars, and the outer sides of the prestressed tendons and the transverse reinforcing bars are poured with concrete connecting parts. The section size of the concrete connection is the same as that of the prefabricated bridge piece.

In the prior art, the prefabricated assembling method generally involves prefabricating bridge pieces, but no prestressing is applied during prefabrication, and prestressed rib channels are reserved in the prefabricated bridge pieces. Enter the reserved channel for tensioning, and process the joints to complete the assembly of a section of prefabricated bridge pieces. Repeat the above operations to complete the installation of a span beam. This method will cause continuous prestressing in a span beam, and the joints of the prefabricated bridge pieces will become weak spots, which are easy to be fractured. Bridge piece development.

After adopting this technical solution, only prestress is applied to each prefabricated bridge piece, and there is no prestress at the joints between the prefabricated bridge pieces. Under the influence of prestress, the probability of cracks is greatly reduced, and the cracks will not develop to the adjacent prefabricated bridge pieces, and the service life of the bridge will be increased. Moreover, this solution greatly shortens the construction time of the bridge, improves the engineering efficiency, and reduces the adverse impact of the construction project on the traffic.

Preferably, the upper part of the prefabricated bridge piece is provided with two layers of prestressed tendons, wherein the prestressed tendons of the lower layer are arranged in an arc shape and are bent upward.

After adopting this technical scheme, the force of the arc-shaped steel bar connection is relatively uniform in the thickness direction and the horizontal direction, the arc-shaped steel connection mode has less influence on the prefabricated bridge pieces on both sides, and the prefabricated bridge pieces are less prone to cracks.

Preferably, the upper transverse reinforcement is connected by welding, and the lower transverse reinforcement is connected by binding.

After adopting this technical solution, the welding construction personnel in the upper part can directly operate on the bridge deck, and the binding construction personnel in the lower part can operate on the cavity of the box girder and the formwork, which is convenient for construction.

Preferably, the cross section of the prefabricated bridge sheet is provided with an adhesive, and the thickness of the adhesive is 0.5 mm to 1 mm.

If the adhesive is applied too thickly, the volatilization speed of the solvent will be too slow, and the strength will increase slowly. At this time, the adhesive only plays the role of filling, and the adhesive force is not strong. area is reduced. After adopting this technical solution, the moisture in the binder is more easily volatilized, the strength of the binder increases faster, and the situation of lack of glue is avoided at the same time. The binder can make the connection between the newly poured concrete and the prefabricated bridge piece more closely, avoid the joint between the binder and the concrete becoming the weak point of the bridge force, cause stress concentration, and avoid cracks in the joint between the binder and the concrete. , to increase the stability and bearing capacity of the bridge.

Preferably, the spacing between the prestressed tendons is 35-45 cm.

After adopting the technical scheme, it is ensured that the prefabricated bridge piece has sufficient prestress inside, and the construction personnel can have operating space for the welding tools during welding construction, which is convenient for construction.

Preferably, the prestressed rib is connected to the prestressed rib of the adjacent prefabricated bridge piece by welding, and the welding overlap length is not less than 10 times the diameter of the prestressed rib.

After adopting this technical solution, it is ensured that the lap strength of the lap joints between the prestressed tendons meets the requirements of the specification, and the bending resistance, shear resistance and bearing capacity of the bridge are guaranteed to meet the requirements.

The construction method of the continuous composite beam of the present invention comprises the following steps:

Step [1]: Make prefabricated bridge pieces;

Step [2]: Build the supports, the distance between the supports is greater than the width of the pier and the span of the bridge;

Step [3]: the two sides of the bridge pier are respectively provided with beams, and the beams are installed on the brackets;

Step [4]: Install lifting equipment on the beam, and the number of lifting equipment is the same as the number of prefabricated bridge pieces in the span;

Step [5]: Hoist the prefabricated bridge pieces, first hoist the prefabricated bridge pieces on the piers, and then hoist the prefabricated bridge pieces in the middle of the span at the same time;

Step [6]: Connect the reinforcing bars at the joints of adjacent prefabricated bridge pieces;

Step [7]: Concrete is poured on the joints of the prefabricated bridge pieces.

The prefabricated bridge piece in the step [1] is prestressed by the pretensioning method, and 35cm-45cm of prestressed tendons are reserved on both sides.

In step [2], before the support is built, excavate the place where the support is to be built, and then pour concrete as the support foundation. The foundation of the support is more stable, preventing quality accidents or safety accidents caused by the settlement of the support foundation during the construction process.

The lifting equipment in step [4] is a gantry crane, and the gantry crane is slidingly connected with the beam. The gantry crane can move to facilitate the movement and positioning of the prefabricated bridge pieces during the hoisting process.

Between steps [6] and [7], adhesive is applied to the sections of the prefabricated bridge pieces, and before the adhesive is applied, the loose concrete at the sections of the prefabricated bridge pieces is removed, impurities are removed, and the prefabricated bridge piece sections are concrete drying. Make the bond between the adhesive and the concrete stronger, increase the bearing capacity and stability of the structure, and avoid the occurrence of cracks.

The thickness of the binder is controlled between 0.5mm and 1mm, and the bonding strength between the binder and the concrete is greater than that of the concrete. It can prevent the bond between the binder and the concrete from becoming the weak point of the bridge, resulting in stress concentration, and can avoid cracks from occurring at the bond between the binder and the concrete, and increase the stability and bearing capacity of the bridge.

After the adhesive is applied on the section of the prefabricated bridge sheet, a pressure of 0.2 Mpa is applied to the adhesive for 2 hours. After adopting the technical solution, the bonding agent and the concrete surface are more closely combined, and the bonding strength is higher.

Before the adhesive is not solidified, a compressive stress is maintained at the joint, and the compressive stress is not less than 0.3Mpa.

After adopting the technical scheme, it can ensure that there is a certain prestress at the joints of the prefabricated bridge pieces, so that the bearing capacity of the bridge is higher.

To sum up, due to the adoption of the above-mentioned technical solutions, the beneficial effects of the present utility model are:

1. The construction time of the bridge is greatly shortened, the engineering efficiency is improved, and the adverse impact of the construction project on the traffic is reduced. Compared with the existing integral prestress distribution, this segmented prestress distribution can reduce the bridge's impact. Cracks, fewer cracks are created at the joints, and the service life of the bridge is increased.

2. The upper part of the prefabricated bridge piece is provided with two layers of prestressed tendons, of which the prestressed tendons of the lower layer are set to be arc-shaped and curved upward. The connection method has less influence on the prefabricated bridge pieces on both sides, and the prefabricated bridge pieces are less prone to cracks.

3. The upper transverse steel bars are connected by welding, and the lower transverse steel bars are connected by binding. The welding construction personnel in the upper part can directly operate on the bridge deck, and the binding construction personnel in the lower part can operate on the box girder cavity and template, which is convenient for construction. .

4. The cross-section of the prefabricated bridge piece is provided with a binder, and the thickness is 0.5mm to 1mm. The strength of the binder increases faster, and at the same time, it avoids the lack of glue. The adhesive can make the connection between the newly poured concrete and the prefabricated bridge sheet more closely, avoid the bond between the adhesive and the concrete becoming the weak point of the bridge force, causing stress concentration, and avoiding cracks in the bonding of the adhesive and the concrete. , to increase the stability and bearing capacity of the bridge.

5. The spacing between the prestressed tendons is 35-45cm, which ensures that the prefabricated bridge pieces have sufficient prestressing, and the construction personnel can operate the welding tools during welding construction, which is convenient for construction.

6. The lap length is not less than 10 times the diameter of the prestressed tendons, to ensure that the lap strength of the lap joints between the prestressed tendons meets the requirements of the specification, and the bending resistance, shear resistance and bearing capacity of the bridge meet the requirements.

Description of drawings

The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

Fig. 1 is the bridge structure schematic diagram of Embodiment 1;

Figure 2 is a schematic diagram of the structure of the prefabricated bridge piece of No. 1;

Figure 3 is a schematic diagram of the structure of the prefabricated bridge piece of No. 2;

Fig. 4 is the structural schematic diagram of No. ③ prefabricated bridge piece;

Figure 5 is a schematic diagram of the structure of the bracket and the gantry crane;

Figure 6 is a diagram of the arrangement of reinforcement at the joint.

Among them, prefabricated bridge pieces No. 1-①, prefabricated bridge pieces No. 2-②, prefabricated bridge pieces No. 3-③, 4-bridge pier, 5-support, 6-auxiliary support, 7-beam, 8-gantry crane, 9-bridge face, 10-prestressed tendons, 11-arc bars, 12-transverse bars.

Detailed ways

All features disclosed in this specification, or all disclosed steps in a method or process, may be combined in any way except mutually exclusive features and/or steps.

The present utility model will be described in detail below with reference to FIGS. 1 to 6 .

A continuous composite beam includes several prefabricated bridge pieces, the several prefabricated bridge pieces are connected in sequence, the prefabricated bridge pieces are provided with prestressed ribs 10, and the prefabricated rib 10 extends out of the section of the prefabricated bridge pieces 35-45 cm, the prestressed tendons 10 are connected with the prestressed tendons 10 of the adjacent prefabricated bridge pieces in one-to-one correspondence, and transverse reinforcement bars 12 are arranged on the prestressed reinforcement bars 10. A concrete connection part is poured, and the cross-sectional dimension of the concrete connection part is the same as that of the prefabricated bridge piece.

The upper part of the prefabricated bridge piece is provided with two layers of prestressed tendons 10 , wherein the prestressed tendons 10 of the lower layer are arranged in an arc shape and are bent upward.

The upper transverse reinforcement 12 is connected by welding, and the lower transverse reinforcement 12 is connected by binding.

The cross section of the prefabricated bridge sheet is provided with an adhesive, and the thickness of the adhesive is 0.5 mm˜1 mm.

The spacing between the prestressed tendons 10 is 35-45 cm.

The prestressed ribs 10 are connected by welding with the prestressed ribs 10 of the adjacent prefabricated bridge pieces, and the welded lap length is not less than 10 times the diameter of the prestressed ribs 10.

The construction method of the continuous composite beam of the present invention comprises the following steps:

Include the following steps:

Step [1]: Make prefabricated bridge pieces. In this embodiment, a total of three specifications of prefabricated bridge pieces are provided, namely No. 1 prefabricated bridge piece 1, No. 2 prefabricated bridge piece 2 and No. ③ prefabricated bridge piece 3, and the size of the prefabricated bridge piece is set according to the specific conditions of the bridge. The concrete pouring process is set in the beam prefabrication field for industrial production, and the prefabricated bridge pieces are constructed using the pretensioning method. In this embodiment, the diameter of the steel bars of the prefabricated bridge pieces is 20 cm, and 35 cm of prestressed bars 10 are reserved on the left and right sides. Leave 30cm ~ 40cm of prestressed tendons. The prestressed tendons of the bridge deck are provided with two layers, and the prestressed tendons of the lower layer are arranged in an arc shape to form an arc-shaped reinforcement bar 11 .

Step [2]: Build supports 5, and the distance between the supports 5 is greater than the width of the pier 4 and the span of the bridge. Before the support 5 is built, excavate the foundation pit at the place where the support is built. The depth of the foundation pit is determined after calculation according to the bearing capacity of the foundation. The plane size of the foundation pit is slightly larger than that of the support 5, and then concrete is poured in the foundation pit as the foundation of the support 5. . Then start the construction of the bracket 5 on the basis.

Step [3]: Install the beams 7 on the bracket 5 and connect them with fasteners. The beams 7 are parallel to each other and located on both sides of the pier 4 . For bridges with large spans, an auxiliary bracket 6 is erected between the two brackets 5 to support the middle of the beam 7. Before the auxiliary bracket 6 is erected, the foundation also needs to be treated so that the foundation of the auxiliary bracket 6 can meet the bearing capacity. requirements. Both the bracket 5 and the auxiliary bracket 5 are connected by fasteners.

Step [4]: Install the gantry crane 8 on the beam, the beam is provided with a track, and the bottom of the gantry crane 8 is provided with rollers to cooperate with the track. In this embodiment, the gantry crane 8 adopts three sets of combined gantry cranes, the rated load of the gantry crane 8 is 200 tons, and two trolleys are arranged on one set of gantry cranes, wherein the rated lifting capacity of each hoist trolley is 100 tons.

Step [5]: Hoist the prefabricated bridge pieces. First, use two gantry cranes 8 on both sides to hoist the prefabricated bridge piece 1 on the pier 4 respectively. After the prefabricated bridge piece 1 is installed firmly, use three gantry cranes 8 at the same time Hoist the remaining two No. ② prefabricated bridge pieces 2 and one No. ③ prefabricated bridge piece 3, so that No. Lay bulkheads and formwork on scaffolding in preparation for joint construction;

Step [6]: Connect the reinforcing bars at the joints of adjacent prefabricated bridge pieces; in this embodiment, the width of the joints is set to 45cm, and the lap length of the prestressed tendons 10 is 25cm, which is welded by electroslag welding. The prestressed tendons of the bridge deck are set to be double-layered, and the prestressed tendons of the lower layer are bent into arcs (ie, arc-shaped reinforcing bars 11). Lay transverse reinforcement bars 12 on the prestressed reinforcement bars 10 and the arc-shaped reinforcement bars 11 . The joints are welded at the upper part and tied at the lower part, so the welding construction personnel at the upper part can directly carry out the operation on the bridge deck, and the binding construction personnel at the lower part can operate on the cavity of the box girder and the formwork. In order to facilitate the construction, the construction personnel can have space to operate the welding tools during construction. The steel bars at the joints are arranged at an interval of 40 cm, and the steel bars are covered with 40 cm intervals at the cross-section, and two rows of steel bars are arranged in the upper part. The upper part is welded, and the lower part only needs to be tied.

Step [7]: Remove the loose concrete at the cross-section of the prefabricated bridge piece, remove impurities such as oil stains and dust, and then pour concrete at the joints, and use the layered method to pour the concrete.

Between steps [6] and [7], apply adhesive to the section of the prefabricated bridge piece. Remove the loose concrete at the section of the prefabricated bridge piece, remove impurities such as oil stains and dust, and dry the concrete at the section of the prefabricated bridge piece, and then apply adhesive on the section of the prefabricated bridge piece. The adhesive used in this example The invention is a chemical concrete mixture made by mixing epoxy resin and cement, and belongs to the commonly used binder in the prior art. The adhesive is spread evenly, the thickness is controlled between 0.5mm and 1mm, and the bonding strength between the adhesive and the concrete is greater than that of the concrete. In order to stabilize the adhesive on the section of the prefabricated bridge sheet, after applying the adhesive, apply pressure to the adhesive for 2 hours, and the pressure is 0.2Mpa. Before the adhesive has solidified, maintain a minimum temporary compressive stress at the joint, and the compressive stress shall not be less than 0.3Mpa. Then, the formwork is supported at the joint and the concrete is poured, and the layered method is used for concrete pouring.

The utility model applies prestressing to each prefabricated bridge piece by the pretensioning method, and only connects the prestressed tendons of the two prefabricated bridge pieces and pours concrete at the joint between the prefabricated bridge pieces, and there is no prestressing at the joint. stress. In this way, the prestress of a span beam is divided into multiple segments, the joints are not affected by the prestress, the probability of cracks is greatly reduced, and the cracks will not develop to the adjacent prefabricated bridge pieces. The use of bridges increased lifespan. Moreover, compared with the existing hanging basket cantilever pouring construction, this solution greatly shortens the construction time of the bridge, improves the engineering efficiency, and reduces the adverse impact of the construction project on traffic.

The above-mentioned embodiments only represent specific implementations of the present application, and the descriptions thereof are specific and detailed, but should not be construed as limiting the protection scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims (6)

1. A continuous composite beam, characterized by: including the prefabricated bridge piece of several, the prefabricated bridge piece of several connects gradually, be provided with prestressing tendons (10) in the prefabricated bridge piece, prestressing tendons (10) stretch out the cross-section 35 ~ 45cm of prefabricated bridge piece, prestressing tendons (10) are connected with prestressing tendons (10) one-to-one of adjacent prefabricated bridge piece, be provided with transverse reinforcement (12) on prestressing tendons (10), concrete connecting portion have been pour in the outside of prestressing tendons (10) and transverse reinforcement (12), the cross sectional dimension of concrete connecting portion is the same with the cross sectional dimension of prefabricated bridge piece.

2. A continuous composite girder according to claim 1, wherein the upper portion of the precast bridge segment is provided with two layers of tendons (10), wherein the tendons (10) of the lower layer are arranged in an arc shape and bent upward.

3. A continuous composite girder according to claim 1, wherein the upper transverse reinforcement (12) is welded and the lower transverse reinforcement (12) is bound.

4. A continuous composite girder according to claim 1, wherein a cross section of the precast bridge deck is provided with an adhesive having a thickness of 0.5mm to 1 mm.

5. A continuous composite beam as claimed in claim 1, characterised in that the spacing between the tendons (10) is 35-45 cm.

6. A continuous composite girder according to claim 1, wherein said tendons (10) are welded to the tendons (10) of the adjacent precast bridge segments with the welded overlapping length not less than 10 times the diameter of the tendons (10).

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