CN103821079A - Combined box girder sea-crossing bridge and construction method thereof - Google Patents

Abstract

A composite box girder cross-sea bridge and a construction method thereof. The cross-sea bridge includes bridge piers and composite box girders supported by bridge piers. The composite box girder is surrounded by a high-strength concrete roof, an ultra-high-performance concrete bottom plate and a pair of ultra-high-performance concrete webs. The external prestressed steel beam has simple structure and good durability. The construction method includes the following steps: S1: construction of pile foundations, caps and piers, and prefabrication of channel beams; S2: pouring high-strength concrete roof to form a one-span composite box girder, tensioning the internal and external prestressed steel in the composite box girder S3: Hoist the composite box girder as a whole on the temporary support; S4: Install the permanent support, and cast the wet joints of adjacent spans; S5: Remove the temporary The internal prestressed steel tendons are stretched at the joints to form a multi-span continuous beam structure; S7: Complete the bridge deck pavement and ancillary facilities construction, the process is simple, and the construction is convenient and fast.

Description

A composite box girder cross-sea bridge and its construction method

technical field

The invention relates to bridge technology, in particular to a combined box girder cross-sea bridge and a construction method thereof.

Background technique

Nowadays, most of the non-navigation holes of cross-sea bridges adopt prestressed concrete box girder, steel-concrete composite beam and steel box girder scheme. For example, the approach bridge of the Hangzhou Bay Bridge adopts a 70m prestressed concrete continuous beam scheme, the approach bridge in the tidal flat area adopts a 50m prestressed concrete continuous beam scheme; A 70m prestressed concrete continuous girder scheme is adopted; a 120m steel truss laminated continuous girder bridge and an 85m continuous steel-concrete composite girder scheme are adopted for the non-navigable opening of the Hong Kong-Zhuhai-Macao Bridge. However, there are many problems in these schemes.

Prestressed concrete box girder bridge is the most widely used bridge structure at present. However, the long-term engineering practice and application status reflect that there are many disadvantages of prestressed concrete box girder bridges. First of all, the internal force generated by the dead load on the control section accounts for more than 80% of the total internal force. The larger the span, the greater the proportion, and it may even reach about 90%. This greatly restricts the spanning capacity of the bridge. Due to the limitation of hoisting capacity at sea, the hoisting tonnage should not be too large, so the span of prestressed concrete box girder bridges is generally not too large. The problems brought about by this are: the number of foundations increases, which in turn leads to a series of problems such as large impact on water flow, many times of beam erection, and long construction period of beam erection; at the same time, due to the low tensile strength of conventional concrete, in order to increase the span as much as possible diameter, long-span bridges usually increase the cross-section rigidity by increasing the cross-sectional size and plate thickness to meet the structural force requirements, which not only increases the self-weight and project cost of the box girder, but also increases the difficulty of construction; in addition, the concrete Due to the complexity of the force and some reasons in the structural treatment and construction of the web, most of the oblique cracks will appear. Such oblique cracks will not only reduce the rigidity and strength of the bridge structure, but also accelerate the corrosion of steel bars. Reinforcement will cause the expansion of the volume, which will cause the concrete to crack, especially in the weak alkaline environment of the ocean, which will further damage the mechanical performance of the concrete, reduce the durability of the material and the bearing capacity of the structure, and affect the beauty of the bridge and service life.

If the sea-crossing bridge adopts a steel structure or a steel-concrete composite structure, its span can indeed be greatly increased compared with the prestressed concrete continuous girder bridge, but seawater is weakly alkaline and has strong corrosion on steel and concrete structures As a result, the durability of steel in the marine environment is poor, and the later maintenance costs are high. Moreover, the cost of bridges with steel structures is high. If the non-navigation holes of the sea-crossing bridge adopt steel structure bridges, the economy will be poor.

At present, some long-span box girder bridges use high-performance lightweight aggregate concrete in the middle of the main span (such as the Stolma Bridge in Norway with a main span of 301m) and steel box girders in the middle of the main span (such as the 330m main span bridge). Chongqing Shibanpo Yangtze River Bridge double-track bridge) and other methods to improve its spanning capacity, and methods such as web vertical prestressed tendons to reduce the risk of box girder cracking. Although these methods have certain effects, the design and construction process of these schemes are relatively complicated At the same time, the problem of box girder cracking has not been fundamentally solved.

In addition, some scholars in China have also proposed a bridge type called prestressed ultra-high performance concrete continuous box girder bridge. There are many problems. First of all, because the thickness of the plate is too thin, too many internal cables cannot be arranged in this bridge type, so there are many external prestressed cables. Since the external cables are exposed to the air, the durability is poor, which brings maintenance problems and later cable replacement problems. The cost is relatively high; and because the whole bridge uses ultra-high performance concrete, and all the slabs are thin-slab structures, the self-weight of the whole bridge is greatly reduced compared with ordinary concrete box girder bridges. The stress amplitude of the main girder is too large, and the fatigue problem caused by it is worthy of further study, which is not good for the long-term stress of the main girder; since the main girder adopts a thin-plate structure, the bending and torsional rigidity of its section is small, so it must be set Many diaphragms are used to resist the torsion and distortion of the main girder, which will also bring about the difficulty of external prestressing arrangement and steering; The problem of local stress exceeding the limit is also worthy of attention.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, to provide a combined box girder cross-sea bridge with simple structure, good durability, suitable for large spans, and broad application prospects, as well as simple technological process, convenient construction, A fast and rapid construction method for a combined box girder cross-sea bridge.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A composite box girder cross-sea bridge, comprising a bridge pier and a composite box girder supported by the bridge pier, the composite box girder is surrounded by a high-strength concrete roof, an ultra-high-performance concrete bottom plate and a pair of ultra-high-performance concrete webs, the combination Inside the box girder, there are external prestressed steel beams and internal prestressed steel beams arranged along the longitudinal direction of the bridge.

As a further improvement of the above technical solution:

The ultra-high-performance concrete bottom plate and a pair of ultra-high-performance concrete webs are integrally prefabricated into a channel beam structure.

The top of the ultra-high-performance concrete web is provided with slots for connecting with the high-strength concrete roof, and there are multiple slots arranged longitudinally along the bridge.

The span of the sea-crossing bridge is 90m-120m.

The sea-crossing bridge is simply supported variable continuous bridge type.

The thickness of the ultra-high-performance concrete bottom plate is 15-20cm, the thickness of the ultra-high-performance concrete web is 16-22cm, the thickness of the high-strength concrete roof is 26-30cm, and 1 Road partition.

A construction method for a combined box girder cross-sea bridge as described above, comprising the following steps:

S1: On-site construction of pile foundations, caps and piers, and at the same time prefabrication of ultra-high-performance concrete webs and ultra-high-performance concrete bottom slabs into channel beams in the prefabrication yard;

S2: Pour a high-strength concrete roof on the channel beam to form a one-span composite box girder, or connect the prefabricated high-strength concrete roof to the channel beam through wet joints to form a one-span composite box girder, and simultaneously tension the composite box girder External and internal prestressed steel beams;

S3: Install temporary supports on the pier, and hoist the combined box girder to the temporary supports as a whole;

S4: Install permanent support, cast-in-place adjacent span wet joints;

S5: After the concrete strength of the adjacent wet joint reaches 90%, the temporary support is removed to complete the system transformation;

S6: Stretch the internal prestressed steel tendons at the wet joints of adjacent spans to form a multi-span continuous beam structure;

S7: Complete the bridge deck pavement and ancillary facilities construction.

As a further improvement of the above technical solution:

When the channel beam is prefabricated, a structure with slots is poured on the top surface of the ultra-high performance concrete web, and a plurality of slots are arranged along the longitudinal direction of the bridge.

The ultra-high-performance concrete bottom plate and the ultra-high-performance concrete web are made of ultra-high-performance concrete with a bending tensile strength of 20MPa-40MPa and a compressive strength of 200MPa-300MPa.

The ultra-high-performance concrete base plate and ultra-high-performance concrete web are poured from active powder concrete, ultra-high-performance fiber-reinforced concrete, grouted fiber concrete, densely reinforced composite materials or engineering cementitious composite materials.

Compared with the prior art, the present invention has the advantages of:

The combined box girder cross-sea bridge of the present invention adopts a combined box girder surrounded by a high-strength concrete roof, an ultra-high-performance concrete bottom plate and a pair of ultra-high-performance concrete webs, an ultra-high-performance concrete bottom plate and a pair of ultra-high-performance concrete webs The slab can ensure that the combined box girder has sufficient strength and low thickness requirements, and can significantly reduce the self-weight of the combined box girder, thereby effectively improving the spanning capacity of the combined box girder and enhancing its seismic performance; due to the light weight of the combined box girder, the span Therefore, the number of piers can be significantly reduced, the project cost can be reduced, and the impact on ocean currents can be reduced; due to the high density of ultra-high performance concrete, its durability indicators such as corrosion resistance are greatly improved compared with ordinary concrete, and can be easily It is well adapted to the weak alkaline environment of the ocean, and has excellent overall durability; the ultra-high-performance concrete floor and ultra-high-performance concrete web can resist the tensile stress that may occur in long-span bridges, greatly improving the durability of offshore bridge structures and reducing box load. The cracking risk of the beam makes the present invention have sufficient protection in preventing box girder cracking; the composite box girder cross-sea bridge of the present invention is simple in structure, light in weight, easy to construct, can effectively reduce the cracking risk of concrete box girder, and is durable It has good performance and is suitable for the construction of long-span bridges, especially the non-navigation holes of sea-crossing bridges, and has broad application prospects.

In the construction method of the combined box girder cross-sea bridge of the present invention, the ultra-high-performance concrete web and the ultra-high-performance concrete bottom plate are prefabricated into channel beams in the prefabrication field, and the high-strength concrete roof can be cast-in-situ or prefabricated, thereby greatly shortening the bridge The construction time is simple, the technological process is simple, and the demand for construction equipment is low, which ensures the construction feasibility of the present invention; and the construction is simple, fast and rapid, which is of great significance for ensuring the construction period and improving construction efficiency.

Description of drawings

Fig. 1 is a schematic structural view of the composite box girder cross-sea bridge of the present invention.

Fig. 2 is an enlarged cross-sectional view of A-A in Fig. 1 .

FIG. 3 is an enlarged cross-sectional view taken along line B-B of FIG. 1 .

Fig. 4 is an enlarged cross-sectional view taken along line C-C of Fig. 3 .

Fig. 5 is a schematic flow chart of the construction method of the composite box girder cross-sea bridge of the present invention.

Fig. 6 is a schematic structural view of the construction method of the composite box girder cross-sea bridge of the present invention when it proceeds to step S3.

Fig. 7 is a structural schematic view of the construction method of the composite box girder cross-sea bridge of the present invention when it is carried out to step S4.

Fig. 8 is a schematic structural view of the construction method of the composite box girder cross-sea bridge of the present invention when it is carried out to step S6.

Fig. 9 is a schematic diagram of the structure of the construction method of the composite box girder cross-sea bridge of the present invention when step S7 is carried out.

Each label in the figure means:

1. Bridge pier; 2. Composite box girder; 21. High-strength concrete roof; 22. Ultra-high performance concrete bottom plate; 23. Ultra-high performance concrete web; 231. Card slot; 24. External prestressed steel beam; 25. Transverse 26. Internal prestressed steel tendon; 3. Pile foundation; 4. Cap; 5. Adjacent span wet joints.

Detailed ways

Fig. 1 to Fig. 4 have shown a kind of composite box girder cross-sea bridge embodiment of the present invention, and this cross-sea bridge comprises pier 1 and the composite box girder 2 supported by pier 1, and the bottom of pier 1 is made of cap 4 and pile foundation 3 supports, the composite box girder 2 is surrounded by a high-strength concrete top slab 21, an ultra-high performance concrete bottom slab 22 and a pair of ultra-high performance concrete webs 23, inside the composite box girder 2 there are external prestressed steel beams 24 and internal Prestressed steel tendon 26. The combined box girder cross-sea bridge of the present invention adopts a combined box girder 2 surrounded by a high-strength concrete top plate 21, an ultra-high performance concrete bottom plate 22 and a pair of ultra-high performance concrete webs 23, an ultra-high performance concrete bottom plate 22 and a pair of The ultra-high-performance concrete web 23 can ensure that the combined box girder 2 has sufficient strength and low thickness requirements, and can significantly reduce the self-weight of the combined box girder 2, thereby effectively improving the spanning capacity of the combined box girder 2 and enhancing its seismic performance; Due to the light weight and large span of the combined box girder 2, the number of piers 1 can be significantly reduced, the project cost can be reduced, and the impact on ocean currents can be reduced; due to the high density of ultra-high performance concrete, its durability indicators such as corrosion resistance Compared with ordinary concrete, they are greatly improved, can well adapt to the weakly alkaline environment of the ocean, and have excellent overall durability; Stress greatly improves the durability of the bridge structure at sea, reduces the risk of cracking of the box girder, so that the present invention has sufficient protection in preventing cracking of the box girder; the composite box girder cross-sea bridge of the present invention is simple in structure, light in weight, and easy to construct , It can effectively reduce the cracking risk of concrete box girders, and has good durability. It can be applied to long-span bridges, especially the construction of non-navigable holes in cross-sea bridges, and has broad application prospects.

In this embodiment, the ultra-high-performance concrete bottom plate 22 and a pair of ultra-high-performance concrete webs 23 are integrally prefabricated into a channel beam structure, which is convenient for construction and can greatly improve construction efficiency. The top of the ultra-high-performance concrete web 23 is provided with a slot 231 for connecting with the high-strength concrete roof 21. There are multiple slots 231 arranged longitudinally along the bridge. Beam 2 becomes a whole to jointly resist external force.

Further, the span of the sea-crossing bridge is 90m to 120m, and the sea-crossing bridge is a simply supported variable continuous bridge type. The thickness of the ultra-high-performance concrete bottom plate 22 is 15-20cm, the thickness of the ultra-high-performance concrete web 23 is 16-22cm, the thickness of the high-strength concrete roof 21 is 26-30cm, and a The transverse diaphragm 25 and the arrangement density of the transverse diaphragm 25 are appropriate, which can reduce the torsional deformation and distortion deformation of the box girder, and will not affect the installation of the prestressed steel tendons. In this embodiment, the thickness of the ultra-high performance concrete bottom plate 22 is 15 cm, the thickness of the ultra-high performance concrete web 23 is 20 cm, the thickness of the high-strength concrete top plate 21 at the center line of the bridge axis is 30 cm, and the composite box girder 2 is set every 15 meters. 1 road diaphragm 25.

Fig. 5 to Fig. 9 have shown a kind of composite box girder cross-sea bridge construction method embodiment of the present invention, below in conjunction with the composite box girder cross-sea bridge in the above-mentioned embodiment the construction method of composite box girder cross-sea bridge of the present invention will be further carried out illustrate.

The construction method of the combined box girder cross-sea bridge of the present embodiment comprises the following steps:

S1: Construction of the pile foundation 3, cap 4 and bridge pier 1 is carried out on site, and at the same time, the ultra-high performance concrete web 23 and the ultra-high performance concrete bottom plate 22 are prefabricated into channel beams in the prefabrication yard;

S2: Pour the high-strength concrete roof 21 on the channel beam to form a one-span composite box girder 2, or connect the prefabricated high-strength concrete roof 21 to the channel beam through wet joints to form a one-span composite box girder 2, and stretch the composite box girder at the same time The externally prestressed steel tendons 24 and the internally prestressed steel tendons 26 in the box girder 2;

S3: install a temporary support on the pier 1, and hoist the combined box girder 2 onto the temporary support as a whole;

S4: Install permanent support, cast-in-place adjacent span wet joints 5;

S5: After the concrete strength of the adjacent wet joint 5 reaches 90%, the temporary support is removed to complete the system transformation;

S6: Stretch prestressed steel tendons in the body at 5 adjacent span wet joints to form a multi-span continuous beam structure;

S7: Complete the bridge deck pavement and ancillary facilities construction.

In the construction method of the combined box girder cross-sea bridge of the present invention, the ultra-high-performance concrete web 23 and the ultra-high-performance concrete bottom plate 22 are prefabricated into channel beams in the prefabrication field, and the high-strength concrete top plate 21 can be cast-in-situ or prefabricated, thereby The time for bridge construction is greatly shortened, the technological process is simple, and the demand for construction equipment is low, which ensures the feasibility of the construction of the present invention; and the construction is simple, fast and rapid, which is of great significance for ensuring the construction period and improving construction efficiency.

In this embodiment, when the channel beam is prefabricated, a structure with slots 231 is poured on the top surface of the ultra-high performance concrete web 23, and there are multiple slots 231 arranged longitudinally along the bridge, so that the ultra-high performance concrete web 23 It has higher connection strength with the high-strength concrete roof 21.

In this embodiment, the ultra-high performance concrete bottom plate 22 and the ultra-high performance concrete web 23 are made of ultra-high performance concrete with a bending tensile strength of 20MPa-40MPa and a compressive strength of 200MPa-300MPa.

In this embodiment, the ultra-high-performance concrete bottom plate 22 and the ultra-high-performance concrete web 23 are poured from reactive powder concrete, ultra-high-performance fiber-reinforced concrete, or grouted fiber concrete, or densely reinforced composite materials or engineering cementitious composite materials. , This embodiment selects active powder concrete.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. A combined box girder cross-sea bridge, comprising a bridge pier (1) and a combined box girder (2) supported by the bridge pier (1), characterized in that: the combined box girder (2) is made of a high-strength concrete roof (21) , an ultra-high performance concrete bottom plate (22) and a pair of ultra-high performance concrete webs (23), the composite box girder (2) is arranged with internal prestressed steel tendons (26) and external prestressed beams (26) along the longitudinal direction of the bridge Steel Beam (24). 2. The combined box girder cross-sea bridge according to claim 1, characterized in that: the ultra-high performance concrete floor (22) and a pair of ultra-high performance concrete webs (23) are integrally prefabricated into a channel beam structure . 3. The combined box girder cross-sea bridge according to claim 1 or 2, characterized in that: the top of the ultra-high performance concrete web (23) is provided with a slot (231) for connecting with the high-strength concrete roof (21) ), there are multiple slots (231) arranged longitudinally along the bridge. 4. The combined box girder sea-crossing bridge according to claim 1 or 2, characterized in that: the span of the sea-crossing bridge is 90m-120m. 5. The combined box girder sea-crossing bridge according to claim 1 or 2, characterized in that: the sea-crossing bridge is a simple-support variable-continuous bridge type. 6. The composite box girder cross-sea bridge according to claim 1 or 2, characterized in that: the thickness of the ultra-high performance concrete floor (22) is 15-20 cm, and the thickness of the ultra-high performance concrete web (23) is 16-22cm, the thickness of the high-strength concrete roof (21) is 26-30cm, and a transverse partition (25) is arranged every 15-20m in the composite box girder (2). 7. A construction method for the combined box girder cross-sea bridge according to any one of claims 1 to 6, characterized in that: comprising the following steps: S1: Construction of pile foundation (3), cap (4) and bridge pier (1) is carried out on site, and ultra-high performance concrete web (23) and ultra-high performance concrete bottom plate (22) are prefabricated in the prefabrication yard at the same time channel beam; S2: Pour the high-strength concrete roof (21) on the channel beam to form a one-span composite box girder (2), or connect the prefabricated high-strength concrete roof (21) to the channel beam through wet joints to form a one-span composite box girder (2), while tensioning the external prestressed steel tendons (24) and the internal prestressed steel tendons (26) in the combined box girder (2); S3: Install temporary supports on the pier (1), and hoist the combined box girder (2) onto the temporary supports as a whole; S4: Install permanent support, cast-in-place adjacent span wet joints (5); S5: After the concrete strength of the adjacent wet joint (5) reaches 90%, the temporary support is removed to complete the system transformation; S6: Stretch the internal prestressed steel beam at the adjacent span wet joints (5) to form a multi-span continuous beam structure; S7: Complete the bridge deck pavement and ancillary facilities construction. 8. The construction method according to claim 7, characterized in that: when the channel beam is prefabricated, a structure with a slot (231) is poured on the top surface of the ultra-high performance concrete web (23), and the There are multiple card slots (231) arranged longitudinally along the bridge. 9. The construction method according to claim 7, characterized in that: the ultra-high performance concrete floor (22) and the ultra-high performance concrete web (23) have a bending tensile strength of 20MPa-40MPa and a compressive strength of 200MPa- Made of 300MPa ultra-high performance concrete. 10. The construction method according to any one of claims 7 to 9, characterized in that: the ultra-high performance concrete floor (22) and the ultra-high performance concrete web (23) are made of active powder concrete, ultra-high performance concrete Fiber-reinforced concrete, grouted fiber concrete, densely reinforced composite materials or engineering cementitious composite materials are poured.

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