Construction method for building cable-stayed bridge cross beam section through existing bridge

Abstract

The invention relates to a construction method for building a cable-stayed bridge cross beam section by using an existing bridge, which comprises the following steps of: S1, building a full framing on the existing bridge, and sequentially finishing the pouring of a No.0 cross beam section and the installation of a pair of cable-stayed bridge main towers on the full framing; s2, pouring, steel beam tensioning and maintenance and stay cable tensioning of first to tenth cross beam sections on the two sides of a cable-stayed bridge main tower are sequentially completed on the full framing; and S3, after midspan closure section pouring, steel beam tensioning and maintenance are sequentially completed on the existing bridge, the full framing and the existing bridge are sequentially dismantled, and the cable-stayed bridge cross beam is obtained. The method has the advantages that the existing bridge is fully utilized to build the cable-stayed bridge cross beam, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and in particular to a construction method for building the crossbeam segments of a cable-stayed bridge by using an existing bridge. Background Art

[0002] In the regulation project of inland waterway, the cross-channel bridges must meet the requirements of the clearance scale of the waterway planning (including the navigable net width and height), and any bridge that does not meet these standards must be rebuilt. At present, many inland bridges adopt a multi-span structure and set piers in the river channel, which will hinder the navigability of the inland waterway. To solve this problem, the common strategy is to demolish the original multi-span bridge and build a new single-span bridge on the original site. However, this reconstruction method often requires changing the road alignment. Especially for railway bridges and rail transit bridges that are difficult to realign, have too high reconstruction costs or unacceptable social impacts, reconstruction cannot be carried out. This directly hinders the implementation of the waterway according to the planned grade and may affect the overall efficiency of the inland waterway network.

[0003] The traditional construction techniques for the main girders of cross-channel cable-stayed bridges include the cantilever casting method and the cantilever assembly method. The cantilever casting method has the following problems: ① The construction period is long, the concrete curing time is long and is greatly affected by the climate, resulting in a slow overall construction progress; ② It is difficult to guarantee the construction accuracy, the deformation of the hanging basket is difficult to control, and the shrinkage and creep of the concrete may cause large deformations of the main girder; ③ The construction risk is high, and the high-altitude operation increases the risk that the concrete quality is difficult to guarantee. The cantilever assembly method also faces challenges: ① The prefabrication and transportation of components require high precision, and the transportation and hoisting of segments are difficult; ② Connection and waterproofing problems, the reliability of the connection parts of the segments is in doubt, and the waterproof treatment at the assembly is complex; ③ The construction control is difficult, and the requirements for the linear control of the main girder and the closure accuracy are extremely high.

[0004] During the above-mentioned engineering reconstruction process, it is necessary to wait until the original bridge is completely demolished before starting the construction of the new bridge. During the construction of the new bridge, it is also necessary to pre-build a construction trestle in advance and install the components of the new bridge on the trestle. This construction method not only makes the old bridge unable to provide any auxiliary function for the construction of the new bridge, but also does not conform to the construction concept of green environmental protection and economic saving. At the same time, it will also affect the navigation of the waterway and reduce the construction efficiency. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a construction method for building the crossbeam segments of a cable-stayed bridge by using an existing bridge in view of the above deficiencies in the prior art, which has the advantages of making full use of the existing bridge to build the crossbeam of the cable-stayed bridge and improving the construction efficiency.

[0006] The above invention object of the present invention is achieved through the following technical solutions: A construction method for building the crossbeam segments of a cable-stayed bridge by using an existing bridge includes the following steps. S1 Erect a full hall formwork support on the existing bridge, and successively complete the casting of the 0# crossbeam segment and the installation of a pair of cable-stayed bridge main towers on the full hall formwork support; S2 Successively complete the casting, steel strand tensioning and curing of the 1-10# crossbeam segments on both sides of the cable-stayed bridge main tower on the full hall formwork support, and the cable-stayed cable tensioning; S3 After successively completing the casting, steel strand tensioning and curing of the mid-span closure segment on the existing bridge, remove the full hall formwork support and the existing bridge successively to obtain the cable-stayed bridge crossbeam.

[0007] Further, in the S1, the full hall formwork support is a bowl-lock type scaffolding with a wall thickness of Φ48*3.5mm. The spacing of the support erection is 60cm×60cm both longitudinally and transversely, and it is encrypted to 60cm×30cm at the crossbeam. The vertical poles are connected by transverse rods to form a grid shape. The step distance of the horizontal rods is 1.2m. Longitudinal and transverse scissors braces are arranged on the outside of each section of the support to connect each section of the support into a whole, and steel pipes plus bottom supports are used to support on the support foundation to make the whole support form a whole.

[0008] Further, in the S1, the 0# crossbeam segment is cast by the method of layered casting and symmetric casting. The layered thickness is determined according to the vibration capacity of the concrete and the formwork height, and the layered thickness is controlled within 30-50cm.

[0009] Further, in the S1, the height of the cable-stayed bridge main tower above the bridge deck is 52m. The cable-stayed bridge main tower adopts a steel box section with an outer dimension of 2.84×8m at the bottom and 2.94×3m at the top. The cable-stayed bridge main tower is divided into 11 segments, which are processed in segments at the factory. The segments are transported to the bridge site and hoisted and installed by an AC3000-ton crane.

[0010] Further, in the S2, the cable-stayed bridge crossbeam is divided into 1-10# crossbeam segments along the length direction, with a size of 7.0m×43.0m×2.93m and a weight of 120t.

[0011] Further, in the S2, each time a crossbeam segment is cast. After the casting is completed and cured for 10 days, the prestress tensioning of the crossbeam segment is carried out, and then the cable-stayed cables are installed and tensioned. After each segment is completed and the cable-stayed cables participate in the force, the next segment can be cast.

[0012] Further, in the S2, the bearing capacity of the existing bridge is checked by using finite element software to control the bearing capacity of the existing bridge to meet the requirements theoretically, and during the construction, the deflection of the existing bridge is observed to clarify the deviation range between the actual construction state and the theoretical calculated value.

[0013] Still further, in the S2, control the bearing capacity of the existing bridge to meet the ultimate bearing capacity requirements under the construction state specified in the bridge design code.

[0014] Furthermore, in the step S2, the deflection deviation range of the existing bridge is controlled within L / 2000 and below 1 cm, where L is the span.

[0015] Furthermore, in the step S3, formwork is erected on the existing bridge, steel bars, prestressed ducts are installed, concrete is poured and cured, and prestressed steel tendons are tensioned. Finally, the mid-span closure section is built and the system conversion is completed.

[0016] Furthermore, in the step S3, the bottom elevation of the crossbeam of the cable-stayed bridge is 0.8 m from the lowest point of the deck of the existing bridge. After the construction of the crossbeam of the cable-stayed bridge is completed, it is necessary to demolish the hollow slabs of the existing bridge in a limited space. Holes are pre-drilled at the hinge joints at the ends of each hollow slab as channels for later diamond wire saw cutting. After the hinge joints between each hollow slab are cut by the diamond wire saw, a boat is used to enter under the bridge, and the hollow slabs are jacked up by brackets and transported away one by one.

[0017] In summary, the beneficial technical effects of the present invention are as follows: The present invention proposes a technology for constructing the crossbeam of a cable-stayed bridge by using an existing bridge. A full hall scaffold is erected using the existing bridge to construct the crossbeam of the cable-stayed bridge, avoiding the erection of an additional construction platform and improving the construction efficiency. The present invention proposes a technology for demolishing an existing bridge in a small clearance environment. By pre-drilling holes at the ends of the hollow slabs as channels for later diamond wire saw cutting, after cutting the hinge joints between each hollow slab, a boat is used to enter under the bridge, and the hollow slabs are jacked up by brackets and transported away one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the cable-stayed bridge according to Embodiment 1 of the present invention.

[0019] Figure 2 is a schematic connection diagram between the existing bridge, the full hall scaffold and the crossbeam of the cable-stayed bridge according to Embodiment 2 of the present invention.

[0020] Figure 3 is a finite element model diagram of the cable-stayed bridge according to Embodiment 3 of the present invention.

[0021] Figure 4 is a calculation model and result diagram of the load transferred from the cable-stayed bridge to the old bridge during the construction stage according to Embodiment 3 of the present invention.

[0022] Figure 5 is a finite element model diagram of the existing bridge according to Embodiment 3 of the present invention.

[0023] Figure 6 is a bending moment envelope diagram of the existing bridge under the ultimate bearing capacity state during the construction process according to Embodiment 3 of the present invention.

[0024] Figure 7It is the shear force envelope diagram under the ultimate bearing capacity state during the construction process of the existing bridge in Embodiment 3 of the present invention. Detailed implementation manners

[0025] In order to make the technical means, creative features, achieved purposes and functions realized by the present invention clearer and easier to understand, the present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0026] Embodiment 1: Refer to Figure 1 , a construction method for building a segment of a cable-stayed bridge crossbeam using an existing bridge disclosed in the present invention, includes the following steps. S1 Build a full hall formwork support on the existing bridge, and successively complete the casting of the 0# crossbeam segment and the installation of a pair of cable-stayed bridge main towers on the full hall formwork support. S2 Successively complete the casting, steel strand tensioning and curing of the 1-10# crossbeam segments on both sides of the cable-stayed bridge main tower on the full hall formwork support, and the cable-stayed cable tensioning. S3 After successively completing the casting, steel strand tensioning and curing of the mid-span closure segment on the existing bridge, remove the full hall formwork support and the existing bridge in sequence to obtain the cable-stayed bridge crossbeam.

[0027] Embodiment 2: Refer to Figure 2 , a construction method for building a segment of a cable-stayed bridge crossbeam using an existing bridge disclosed in the present invention, different from Embodiment 1 in that the specific implementation manner of S1 is The full hall formwork support is a bowl-coupled scaffolding with a wall thickness of Φ48*3.5mm. The spacing of the support erection is 60cm×60cm both longitudinally and transversely, and is encrypted to 60cm×30cm at the crossbeam. The vertical poles are connected by transverse bars to form a grid shape. The step distance of the horizontal bars is 1.2m. Longitudinal and transverse scissors braces are arranged on the outside of each section of the support to connect each section of the support into a whole, and the whole support is formed by using steel pipes plus bottom supports to support on the support foundation. The 0# crossbeam segment is cast in layers and symmetrically. The layer thickness is determined according to the vibration ability of the concrete and the formwork height, and the layer thickness is controlled within 30-50cm. The height of the cable-stayed bridge main tower above the bridge deck is 52m. The cable-stayed bridge main tower adopts a steel box section with an outer dimension of 2.84×8m at the bottom and 2.94×3m at the top. The cable-stayed bridge main tower is divided into 11 segments, which are processed in segments at the factory. The segments are transported to the bridge site and hoisted and installed by an AC3000-ton crane.

[0028] Embodiment 3: A construction method for building a segment of a cable-stayed bridge crossbeam using an existing bridge disclosed in the present invention, different from Embodiment 1 in that the specific implementation manner of S2 is The cross beams of the cable-stayed bridge are divided into cross beam segments numbered 1 to 10 along the length direction, with dimensions of 7.0m × 43.0m × 2.93m and a weight of 120t. One cross beam segment is poured each time. After the pouring is completed and cured for 10 days, prestress tensioning of the cross beam segment is carried out, and then the stay cables are installed and tensioned. After each segment is completed and the stay cables participate in the force, the next segment can be poured.

[0029] The bearing capacity of the existing bridge is checked by using finite element software to control the bearing capacity of the existing bridge to theoretically meet the ultimate bearing capacity requirements under the construction state specified in the bridge design code. During construction, the deflection of the existing bridge is observed to clarify that the deviation range between the actual construction state and the theoretical calculation value is within L / 2000 and less than 1 cm, where L is the span.

[0030] From Figures 3 to 7 It can be seen that during the construction of the cross beams of the cable-stayed bridge, the load transferred to the old bridge can meet the construction requirements, that is, the bending moment and shear force in the ultimate bearing capacity state can meet the construction needs.

[0031] Example 4: A construction method for building cross beam segments of a cable-stayed bridge using an existing bridge disclosed in the present invention is different from Example 1 in that the specific implementation of S3 is Erect formwork, install steel bars, prestressed ducts on the existing bridge, pour concrete and cure it, tension the prestressed steel bundles, and finally build the mid-span closure section and complete the system conversion; The lowest elevation of the bottom of the cross beam of the cable-stayed bridge from the bridge deck of the existing bridge is 0.8m. After the construction of the cross beam of the cable-stayed bridge is completed, it is necessary to demolish the full hall formwork and the hollow slabs of the existing bridge in a limited space. The full hall formwork is demolished manually. The existing bridge needs to be pre-drilled at the hinge joints at the ends of each hollow slab beam as a channel for later diamond wire saw cutting. After the hinge joints between each hollow slab are cut by the diamond wire saw, a boat enters under the bridge, the hollow slabs are jacked up by the support, and the hollow slabs are transported away one by one.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A construction method for building a cable-stayed bridge crossbeam segment using an existing bridge, characterized in that: The following steps are included: S1 built a full-bridge support on the existing bridge, and cast the No. 0 beam segment and installed a pair of main towers of the cable-stayed bridge on the full-bridge support; S2 completes the casting of beam segments 1 to 10 on both sides of the main tower of the cable-stayed bridge, tensioning and curing of steel strands, and tensioning of the cable stays in sequence on the full-bridge support; After S3 completed the casting of the mid-span closure section, steel strand tensioning and maintenance on the existing bridge, it dismantled the full-span support and the existing bridge in turn to obtain the cable-stayed bridge beam.

2. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S1, the full-hall support is a bowl-hook type scaffolding with a wall thickness of Φ48*3.5mm. The vertical and horizontal spacing of the support is 60cm×60cm, and the spacing at the crossbeam is increased to 60cm×30cm. The vertical poles are connected by horizontal poles to form a grid. The horizontal pole pitch is 1.2m. Vertical and horizontal scissors braces are arranged on the outside of each section of the support to connect the sections of the support into a whole, and are supported on the support foundation with steel pipes and bottom supports to form the entire support as a whole.

3. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S1, the No. 0 beam segment is cast in layers and symmetrically, and the layer thickness is determined according to the vibration capacity of the concrete and the height of the formwork, and the layer thickness is controlled at 30-50 cm.

4. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S1, the main tower of the cable-stayed bridge above the bridge deck is 52m high. The main tower of the cable-stayed bridge adopts a steel box section with an outer dimension of 2.84×8m at the bottom and 2.94×3m at the top. The main tower of the cable-stayed bridge is divided into 11 segments, which are processed in the factory and transported to the bridge site and hoisted and installed using an AC3000-ton crane.

5. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In the S2, the cable-stayed bridge beam is divided into beam segments No. 1 to No. 10 along the length direction, with dimensions of 7.0m×43.0m×2.93m and a weight of 120t.

6. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S2, one beam segment is cast each time. After casting is completed and cured for 10 days, the beam segment is prestressed and tensioned, and then the inclined cables are installed and tensioned. After each segment is completed and the inclined cables are subjected to stress, the next segment can be cast.

7. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S2, the bearing capacity of the existing bridge is verified by using finite element software to control the bearing capacity of the existing bridge to meet the requirements in theory, and during construction, the deflection of the existing bridge is observed to clarify the deviation range between the actual construction status and the theoretical calculated value.

8. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 7, characterized in that: In S2, the bearing capacity of the existing bridge is controlled to meet the ultimate bearing capacity requirements under construction specified in the bridge design specifications, and the deflection deviation range of the existing bridge is controlled to be L / 2000 and below 1 cm, where L is the span.

9. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S3, formwork is set up on the existing bridge, steel bars and prestressed pipes are installed, concrete is poured and maintained, and prestressed steel strands are tensioned, and finally a mid-span closing section is built and the system conversion is completed.

10. The construction method of using an existing bridge to construct a cable-stayed bridge crossbeam segment according to claim 1, characterized in that: In S3, the distance between the bottom of the cross beam of the cable-stayed bridge and the lowest elevation of the bridge deck of the existing bridge is 0.8m. After the construction of the cross beam of the cable-stayed bridge is completed, the hollow slab of the existing bridge needs to be dismantled in a limited space. A hole is opened in advance at the hinge joint of each hollow slab beam end as a channel for subsequent diamond wire saw cutting. After the diamond wire saw cuts off the hinge joint between each hollow slab, a boat enters under the bridge, and the hollow slab is lifted up by a bracket to be transported away piece by piece.

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