Hybrid bridge deck structure for oversized span cable-stayed bridge engineering and construction method thereof

Abstract

A cable-stayed bridge comprises a midspan area, near-tower areas and side span areas, the midspan area is arranged in the middle of the cable-stayed bridge, the near-tower areas are located on the left side and the right side of the midspan area, and the side span areas are located on the left side and the right side of the near-tower areas. The midspan area adopts a steel-ultra-high performance concrete combined bridge deck slab, the near-tower area adopts an ultra-high performance concrete bridge deck slab, and the side span area adopts a common concrete bridge deck slab; the midspan area and the near-tower area are connected through a first variable-thickness ultrahigh concrete combination section, and the near-tower area and the side span area are connected through a second variable-thickness concrete combination section. The structure not only well adapts to and meets the stress requirement, but also is convenient to construct and lower in later maintenance cost, and has obvious engineering technical economic advantages.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering bridges, and in particular to a hybrid bridge deck structure of a super-long span cable-stayed bridge and a construction method thereof. Background Art

[0002] Large-span cable-stayed bridges play a vital role in basic transportation. Moreover, with the advancement of bridge technology, considering various influencing factors such as navigation and flood control on large rivers, cable-stayed bridges with a span of more than one kilometer have become the focus of bridge construction and technological breakthroughs.

[0003] As the span of cable-stayed bridges increases, the main beam of cable-stayed bridges with a span of more than a kilometer becomes heavier, the tower becomes taller, and the cable becomes longer, which is significantly different from conventional span cable-stayed bridges. In particular, the increase in the main beam's deadweight causes the bridge structure to be subjected to not only huge forces, but also a significant increase in the amount of work required for the tower, tower foundation, and cable, resulting in a sharp drop in the economic efficiency of the project. Therefore, most of the main spans of cable-stayed bridges with a span of more than a kilometer that have been built around the world currently use steel box beams with lighter deadweight. Compared with composite beams and concrete main beams, steel box beams are lighter and stronger, but they also have the disadvantage of low local stiffness of steel bridge decks, which leads to the following technical difficulties: 1) The axial force of the main beam near the bridge tower is huge. To meet the strength and stability requirements of the steel structure, it is necessary not only to increase the plate thickness to resist the axial force, but also to set up a large number of stiffening structures to prevent the components from being compressed and unstable; 2) Due to the thickness of the steel box beam plate and the setting of a large number of components such as stiffening ribs within the bridge tower range, the amount of steel used in the main beam is greatly increased, and the economic efficiency of the project is reduced; 3) Steel box beams usually have two major problems: fatigue cracking of the steel bridge deck and easy damage to the pavement. Therefore, after a certain number of years of service, the bridge needs to be overhauled or renovated, resulting in high subsequent maintenance costs. Summary of the invention

[0004] The present invention proposes a hybrid bridge deck structure and a construction method thereof for a super-large span cable-stayed bridge project, which can well adapt to and meet the force requirements, is convenient to construct, has low subsequent maintenance costs, and has obvious engineering technical and economic advantages.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A hybrid bridge deck structure for a super-large span cable-stayed bridge project, the cable-stayed bridge comprising a mid-span area, a near-tower area and a side span area, the mid-span area being arranged in the middle of the cable-stayed bridge, the side span areas being arranged on the left and right sides of the mid-span area, and the near-tower area being arranged between the mid-span area and the side span area, the near-tower area, the side tower area and the bridge tower being connected by cable-stayed cables to form a single triangular tower bridge structure, wherein the mid-span area adopts a steel-ultra-high performance concrete composite bridge deck, the near-tower area adopts an ultra-high performance concrete bridge deck, and the side span area adopts an ordinary concrete bridge deck; the mid-span area and the near-tower area are connected by a first variable-thickness ultra-high concrete joint section, and the near-tower area and the side span area are connected by a second variable-thickness concrete joint section.

[0007] The pylon divides the cable-stayed bridge into the near-pylon area and the side-pylon area. The length of the mid-span area is 20% of the total length of the center lines of two adjacent pylon bridges of the cable-stayed bridge. The maximum span of the center lines of two adjacent pylon bridges is not less than 800 m, and the side-span is not more than 400 m.

[0008] The steel-ultra-high performance concrete composite bridge deck is laminated from a steel bridge deck structure and an ultra-high performance concrete layer from bottom to top, and the two are connected by stud connectors. The steel bridge deck structure is an orthotropic steel plate.

[0009] The orthotropic steel plate adopts an orthotropic panel structure with open ribs or closed ribs.

[0010] The ultra-high performance concrete composite bridge deck is an equal-thickness plate or a waffle plate structure.

[0011] The first variable-thickness ultra-high concrete joint section adopts a steel stiffening rib plate-variable-thickness ultra-high performance concrete composite bridge deck structure, including a folded steel plate and a T-shaped stiffening plate. The ultra-high performance concrete bridge deck in the near-pylon area reduces in thickness at the first variable-thickness ultra-high concrete joint section and gradually changes into the thickness of the ultra-high performance concrete layer in the mid-span area. The folded steel plate serves as the bottom formwork of the variable-thickness ultra-high performance concrete bridge deck and fits the bottom of the ultra-high performance concrete bridge deck. A T-shaped stiffening plate is arranged at the bottom of the folded steel plate, and the T-shaped stiffening plate is connected to the steel bridge deck structure.

[0012] The second variable-thickness concrete joint section is composed of a mixture of ultra-high performance concrete and ordinary concrete, and its thickness gradually changes from the side-span area thickness to the near-pylon area thickness.

[0013] PBL shear keys embedded in the ultra-high performance concrete bridge deck are arranged on the upper surface of the folded steel plate. The PBL shear keys are formed by transverse bridge deck steel bars passing through the open-hole plate.

[0014] A construction method of a hybrid bridge deck structure as described above includes the following steps:

[0015] S1. Divide the cable-stayed bridge into the main span area, the near-pylon area and the side-span area, and assemble the ordinary concrete bridge deck by segment prefabrication and splicing technology. After assembly, it serves as the side-span area of the cable-stayed bridge.

[0016] S2. Cast the second variable-thickness concrete joint section in situ from the support at the bridge position from the side-span area to the mid-span area side, and form it by mixing and pouring ultra-high performance concrete and ordinary concrete.

[0017] S3. Prefabricate the ultra-high performance concrete bridge deck in the factory by plate units. The plate units are assembled with the steel box through the in-factory wet joint to form a composite beam segment. When the composite beam segments are spliced on-site, the adjacent precast ultra-high performance concrete bridge decks are connected through the cast-in-place wet joint. This composite beam segment is used as the near-tower area and is cast and connected to the side away from the side span of the second variable-thickness concrete joint segment;

[0018] S4. The first variable-thickness ultra-high concrete joint segment is prefabricated as an integral segment in the factory, and then it is cast and connected to the side away from the side span of the S3 side tower area;

[0019] S5. Cast the ultra-high performance concrete layer in the steel-ultra-high performance concrete composite bridge deck between the first variable-thickness ultra-high concrete joint segments on both the left and right sides in S4 at one time. -

[0020] In the present invention, by adopting a steel-ultra-high performance concrete composite bridge deck in the mid-span area, an ultra-high performance concrete bridge deck in the near-tower area, and a normal concrete bridge deck in the side span area, the layout of the spans is flexible, which is beneficial to avoiding the construction of poor geological conditions and deep water foundations, greatly enhancing the applicability to construction conditions and its aesthetic feeling in terms of landscape; effectively solving the technical disadvantages and deficiencies that the steel bridge deck of the cable-stayed bridge with a span of more than one thousand meters is prone to fatigue cracking due to its low local stiffness and the insufficient compressive stability of the steel beam structure in the near-tower area, with low construction cost and maintenance cost, and some structures are prefabricated as integral segments in the factory, which is beneficial to accelerating the construction progress and ensuring the construction quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the cable-stayed bridge in the present invention;

[0022] Figure 2 It is a schematic diagram of the hybrid bridge deck structure in the present invention;

[0023] Figure 3 It is a schematic diagram of the second variable-thickness connection segment;

[0024] Figure 4 It is a schematic diagram of the first variable-thickness connection segment;

[0025] Figure 5 It is a schematic diagram of the structure of the folded steel plate;

[0026] Figure 6 It is a detailed drawing of the bridge deck connection component between the mid-span area and the near-tower area. DETAILED DESCRIPTION OF THE INVENTION

[0027] As Figures 1-5As shown in the figure, a hybrid bridge deck structure for an extra-long-span cable-stayed bridge project is characterized in that the cable-stayed bridge includes a mid-span area 1, a near-tower area 2, and a side-span area 3. The mid-span area 1 is arranged in the middle of the cable-stayed bridge. The near-tower areas 2 are located on the left and right sides of the mid-span area 1. The side-span areas 3 are located on the left and right sides of the near-tower areas 2. Among them, the mid-span area 1 adopts a steel-ultra-high performance concrete composite bridge deck 11, the near-tower areas 2 adopt ultra-high performance concrete bridge decks 21, and the side-span areas 3 adopt ordinary concrete bridge decks 31. The mid-span area 1 is connected to the near-tower areas 2 through a first variable-thickness concrete joint section 4, and the near-tower areas 2 are connected to the side-span areas 3 through a second variable-thickness concrete joint section 5.

[0028] Preferably, the pylon divides the triangular pylon bridge into a near-tower area 2 and a side-tower area 3. The length of the mid-span area 1 is 20% of the total length of the mid-lines of two adjacent pylon bridges of the cable-stayed bridge. The maximum span between the mid-lines of two adjacent pylon bridges is not less than 800m, and the side-span is not more than 400m.

[0029] Preferably, the steel-ultra-high performance concrete composite bridge deck 11 in the mid-span area 1 is composed of a steel bridge deck structure 12 and an ultra-high performance concrete layer 13 laminated from bottom to top. The ultra-high performance concrete layer 13 has a large stiffness, so that the steel bridge deck structure 12 and the paving layer (steel bridge deck structure 12) are thinner than the traditional steel bridge deck. The steel bridge deck structure 12 adopts an orthotropic steel bridge deck. The ultra-high performance concrete layer 13 and the steel bridge deck structure 12 are connected by stud connectors 14.

[0030] Preferably, the ultra-high performance concrete bridge deck 21 in the near-tower area 2 is an equal-thickness reinforced concrete slab, which is precast in plate units in the factory and assembled with a steel box into a composite beam segment through a wet joint in the factory. When the composite beam segments are spliced on site, adjacent precast ultra-high performance concrete bridge decks 21 are connected through a cast-in-place wet joint.

[0031] Preferably, the first variable-thickness concrete joint section 4 between the main span area 1 and the near-tower area 2 adopts a steel stiffening rib-variable-thickness ultra-high performance concrete composite bridge deck structure, which gradually changes the thickness of the ultra-high performance concrete bridge deck 21 in the near-tower area 2 to the thickness of the ultra-high performance concrete layer 13 in the steel-ultra-high performance concrete composite bridge deck 11 in the mid-span area 1 through a variable-thickness reinforced ultra-high performance concrete slab structure.

[0032] Preferably, the steel stiffening rib-variable-thickness ultra-high performance concrete composite bridge deck structure includes a folded steel plate 41 and a T-shaped stiffening plate 42. The folded steel plate 41 serves as the bottom formwork of the variable-thickness ultra-high performance concrete bridge deck 21 and fits the bottom of the ultra-high performance concrete bridge deck 21. The T-shaped stiffening plate 42 is arranged at the bottom of the folded steel plate 41 and is connected to the steel bridge deck structure 12. The T-shaped stiffening 42 is arranged at the bottom of the folded steel plate 41 to play a stiffening role.

[0033] Preferably, PBL shear keys are arranged on the upper surface of the folded steel plate 41 and embedded in the ultra-high performance concrete bridge deck 21 to enhance the mechanical performance of the first variable-thickness concrete joint section 4. The shear keys are formed by the deck transverse reinforcement 16 passing through the perforated plate 15 with openings.

[0034] Preferably, the second variable-thickness concrete joint section 5 is composed of a mixture of ultra-high performance concrete and normal concrete, and it gradually changes the thickness of the normal concrete bridge deck 31 in the side span area 3 to the thickness of the ultra-high performance concrete bridge deck 21 in the near-tower area 2.

[0035] This hybrid bridge deck solution is applicable to cable-stayed bridge systems with a main span ≥ 800m and a side span ≤ 400m, and is particularly applicable to specific combinations with a main span exceeding 1000m and a side span / main span ratio in the range of 0.25 - 0.4, where the main span is the major span between the centerlines of two adjacent tower bridges; taking the bridge type parameters of the embodiment as an example:

[0036] In this embodiment, the total length of the bridge is 1914m, the main span between the two towers is 1160m, the side span is 350m, among which the mid-span area is 304m, the two near-tower areas on both sides are 401m, and the boundary line between the near-tower area and the side span area is 27m away from the centerline of the bridge tower. The steel bridge deck structure 12 has a thickness of 14mm, and the ultra-high performance concrete layer 13 has a thickness of 60mm.

[0037] The traditional steel bridge deck uses an orthotropic steel bridge deck with a thickness of 16mm, and at the same time, the thickness of the paving layer on the traditional steel bridge is greater than that of the combined bridge deck in this embodiment. The ultra-high performance concrete layer in this embodiment is converted into steel with the same stiffness, and the total cross-sectional area after superimposing the steel bridge deck is 2.28m 2 , The innovation of this embodiment lies in that the mid-span area uses a steel-ultra-high performance concrete composite bridge deck to transition to the ultra-high performance concrete bridge deck in the near-tower area. Comparing with the steel bridge deck used in the mid-span area of the traditional scheme, the characteristics of the calculated cross-section (the transverse cross-section of the mid-span area 1 bridge) are as shown below. It can be seen that the cross-section stiffness of this embodiment has been significantly improved compared with the steel bridge deck.

[0038] Table 1

[0039]

[0040] Comparing with the steel bridge deck used in the mid-span area of the traditional scheme in this embodiment, the main beam weights are as follows. It can be seen that the steel consumption in this embodiment is relatively reduced. Although the ultra-high performance concrete increases the weight, the total weight in the mid-span area is increased or decreased compared with the traditional scheme.

[0041] Table 2

[0042]

[0043] Steel weight index (t / m2 ) It is calculated by multiplying the steel cross-sectional area and the concrete cross-sectional area in Table 1 by the mid-span length and the density of different materials, and then dividing by the bridge deck area.

[0044] In the mid-span area of this implementation case, compared with the traditional steel box girder scheme, the construction period cost is reduced by about 7.6%. The main reason is the reduction in the amount of steel structure used. The maintenance cost during the operation period is reduced by about 64%, and the life cycle cost is reduced by about 31%. The reason is that the ultra-high performance concrete layer becomes a permanent component after casting and forming, and only the wearing layer needs to be replaced within the design service life of the bridge. The service life of the wearing layer is 10 years, so it needs to be replaced 9 times within the 100-year design service life of the bridge; the asphalt pavement layer on the wearing layer has a service life of 25 years, so it needs to be replaced 3 times within the design service life of the bridge; the service life of the anti-corrosion coating of the steel structure is 20 years, so it needs to be replaced 4 times within the design service life of the bridge. The economic effect is significantly better than the traditional steel box girder scheme.

[0045] This embodiment is calculated by finite element software. Comparing with the steel bridge deck in the mid-span area, the calculation results are as follows. It can be seen that the overall force of this embodiment is slightly different from the traditional scheme, but the local stress is significantly reduced and the mechanical performance is excellent.

[0046] Table 3

[0047]

[0048] Table 4

[0049]

[0050] The construction steps of this embodiment are as follows: 1) For the side span area 3 bridge, a normal concrete or steel-normal concrete composite bridge deck is adopted, and the normal concrete bridge deck is constructed together with the beam body by the segment prefabrication and assembly process.

[0051] 2) The second variable-thickness concrete joint section 5 between the normal concrete bridge deck 31 in the side span area 3 and the ultra-high performance concrete bridge deck 21 in the near-tower area 2 is cast in place by scaffolding at the bridge site and is formed by mixing and pouring ultra-high performance concrete and normal concrete.

[0052] 3) The ultra-high performance concrete bridge deck 21 in the near-tower area 2 is prefabricated in the factory by plate units; the plate units are assembled into composite beam segments through wet joints in the factory with steel boxes; when the composite beam segments are spliced on site, adjacent prefabricated ultra-high performance concrete bridge decks are connected through cast-in-place wet joints.

[0053] 4) The first variable-thickness ultra-high performance concrete 4 between the steel-ultra-high performance concrete composite bridge deck 11 in the mid-span area 1 and the ultra-high performance concrete bridge deck 21 in the near-tower area 2 is prefabricated as an integral segment in the factory.

[0054] 5) The ultra-high performance concrete layer 13 in the steel-ultra-high performance concrete composite bridge deck 11 of the middle cross-region 1 is cast in place at the bridge site at one time.

[0055] Although the specific implementation manners of the present disclosure are described above in conjunction with the accompanying drawings, they are not limitations on the protection scope of the present disclosure. Those skilled in the art should understand that, based on the technical solutions of the present disclosure, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present disclosure.

Claims

1. A hybrid bridge deck structure for a super-long span cable-stayed bridge project, the cable-stayed bridge comprising a mid-span area (1), a near-tower area (2) and a side span area (3), the mid-span area (1) being arranged in the middle of the cable-stayed bridge, the side span areas (3) being arranged on the left and right sides of the mid-span area (1), the near-tower area (2) being arranged between the mid-span area (1) and the side span area (3), the near-tower area (2), the side tower area (3) being connected to the bridge tower by a cable-stayed cable to form a single triangular tower bridge structure, characterized in that: in, The mid-span area (1) adopts a steel-ultra-high performance concrete composite bridge deck (11), the near-tower area (2) adopts an ultra-high performance concrete bridge deck (21), and the side span area (3) adopts an ordinary concrete bridge deck (31); the mid-span area (1) and the near-tower area (2) are connected by a first variable-thickness ultra-high concrete joint section (4), and the near-tower area (2) and the side span area (3) are connected by a second variable-thickness concrete joint section (5).

2. The hybrid bridge deck structure for super-large span cable-stayed bridge engineering according to claim 1, characterized in that: The bridge tower divides the triangular tower bridge into a near-tower area (2) and a side-tower area (3). The length of the mid-span area (1) is 20% of the total length of the center line of two adjacent tower bridges of the cable-stayed bridge. The maximum span of the center line of the two adjacent tower bridges is not less than 800m, and the side span is not more than 400m.

3. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 1, characterized in that: The steel-ultra-high performance concrete composite bridge deck (11) is composed of a steel bridge deck structure (12) and an ultra-high performance concrete layer (13) stacked from bottom to top, and the two are connected by a bolt connector (14). The steel bridge deck structure (12) is an orthotropic steel plate.

4. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 3, characterized in that: The orthotropic steel plate adopts an orthotropic panel structure with open ribs or closed ribs.

5. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 1, characterized in that: The ultra-high performance concrete composite bridge deck (21) is a plate of equal thickness or a waffle plate structure.

6. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 1, characterized in that: The first variable thickness ultra-high concrete joint section (4) adopts a steel stiffening rib plate-variable thickness ultra-high performance concrete composite bridge deck structure, including a folded steel plate (41) and a T-shaped stiffening plate (42). The ultra-high performance concrete bridge deck (21) near the tower area (2) has a reduced thickness in the first variable thickness ultra-high concrete joint section (4) and gradually becomes the thickness of the ultra-high performance concrete layer (13) in the mid-span area (1). The folded steel plate (41) serves as a bottom mold of the variable thickness ultra-high performance concrete bridge deck (21) and is adapted to the bottom of the ultra-high performance concrete bridge deck (21). A T-shaped stiffening plate (42) is arranged at the bottom of the folded steel plate (41). The T-shaped stiffening plates (42) extend in the longitudinal direction of the bridge to connect with the steel bridge deck structure (12).

7. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 1, characterized in that: The second variable thickness concrete joint section (5) is composed of a mixture of ultra-high performance concrete and ordinary concrete, and its thickness gradually changes from the thickness of the side span area (3) to the thickness of the near-tower area (2).

8. The hybrid bridge deck structure for a super-long span cable-stayed bridge project according to claim 6, characterized in that: The upper surface of the folded steel plate (41) is provided with a PBL shear key embedded in the ultra-high performance concrete bridge deck (21), and the PBL shear key is formed by the bridge deck transverse steel bars (16) passing through the open perforated plate (15).

9. A construction method for a hybrid bridge deck structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. The cable-stayed bridge is divided into a mid-span area (1), a near-tower area (2) and a side span area (3), and ordinary concrete bridge decks are assembled by means of a segment prefabrication splicing process, and the assembled decks serve as the side span areas (3) of the cable-stayed bridge; S2. The second variable thickness concrete joint section (5) is cast in situ from the side span area (3) to the mid-span area (1) at the bridge location from the bracket, and is cast by mixing ultra-high performance concrete and ordinary concrete; S3. The ultra-high performance concrete bridge deck (21) is prefabricated in a factory in plate units, and the plate units are assembled with steel boxes through wet joints in the factory to form composite beam segments. When the composite beam segments are spliced ​​on site, adjacent prefabricated ultra-high performance concrete bridge decks (21) are connected through cast-in-place wet joints. The composite beam segment serves as the near-tower area (2) and is cast and connected to the second variable thickness concrete joint section (5) away from the side span area (3); S4. The first variable thickness ultra-high concrete joint section (4) is prefabricated in the factory as a whole segment, and then connected to the side tower area (2) away from the side span area (3) by pouring; S5. Casting the ultra-high performance concrete layer in the steel-ultra-high performance concrete composite bridge deck once between the first variable thickness ultra-high concrete joint sections (4) on the left and right sides of S4.

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