A construction method for widening, splicing and reconstruction of a large-span concrete bridge

Abstract

The present invention discloses a construction method for widening and splicing reconstruction of a large-span concrete bridge, comprising the following steps: building a first bridge and a second bridge on both sides of the original old bridge; demolishing the old bridge; rebuilding a third bridge adjacent to the first bridge and a fourth bridge adjacent to the second bridge at the site of the old bridge; closing the outermost lanes of the first bridge and the third bridge and the adjacent sides of the second bridge and the fourth bridge; forming mutually connected skeleton steel structures at the flanges of the adjacent sides of the first bridge and the third bridge and the adjacent sides of the second bridge and the fourth bridge; pouring high-strength concrete at the skeleton steel structure to form a splicing seam connecting the two bridges, and forming a new one-way left-width bridge and a one-way right-width bridge after splicing. The present invention adopts a widening and reconstruction method of double-sided widening + transverse splicing widening to avoid the drawbacks of existing single-sided widening and double-sided widening, and makes the force of the splicing widened post-casting belt within a reasonable range, thereby reducing the cost of later maintenance and repair.

Description

Technical Field

[0001] The invention belongs to the technical field of widening existing bridges, and specifically relates to a construction method for widening, splicing and reconstructing a large-span concrete bridge. Background Art

[0002] With the development of society, the navigation level of rivers will change. Due to the improvement of the navigation level of rivers, a large number of existing bridges do not meet the new navigation standards of rivers and need to be demolished and rebuilt. At the same time, due to the age of existing bridges, the number of lanes is generally small, which is difficult to meet the needs of modern transportation and needs to be widened and renovated.

[0003] During the process of demolition, reconstruction, widening and reconstruction of existing bridges, it is generally required to maintain normal traffic operation of the road section. The current common practices are: 1. Single-side widening and reconstruction; 2. Double-side widening and reconstruction. The construction method of single-side widening and reconstruction is: 1. Build a new bridge on one side of the existing bridge that meets the new navigation standards and new traffic volume requirements; 2. After the new bridge is built, the old bridge is demolished to complete the construction. The construction method of double-side widening and reconstruction is: 1. Build two new bridges on both sides of the existing bridge that meet the new navigation standards and temporary traffic relief needs; 2. After the new bridge is built, the old bridge is demolished; 3. Rebuild the bridge at the site of the old bridge, and together with the first step of building a new bridge, it forms a bridge that meets the new traffic volume requirements.

[0004] Both of these widening and transformation methods have certain advantages and disadvantages:

[0005] 1. Single-sided widening and reconstruction has no intersection between the old and new bridges, and the construction is simple and convenient. However, the overall line shape of the road after completion will deviate greatly from the overall line shape of the road of the existing bridge, which will lead to major changes in the road engineering of the bridge connection section. In cities, it generally involves a large amount of demolition and there is a certain degree of implementation difficulty.

[0006] 2. The overall line shape of the road after the double-sided widening and reconstruction is consistent with the overall line shape of the road of the existing bridge, and the amount of demolition is less than that of the single-sided widening. However, it is implemented in two steps. After completion, there are multiple bridges in the horizontal direction between the new bridge in the first stage and the rebuilt bridge in the second stage, and there are isolation in the same direction, which cannot meet the needs of vehicle interweaving conversion. If the new bridge and the rebuilt bridge are spliced ​​horizontally, the needs of vehicle interweaving conversion can be met.

[0007] At present, the solution of widening existing bridges by transverse widening is relatively mature for small and medium span bridges, such as precast concrete T-beams and small box girder bridges.

[0008] However, there are no relevant engineering cases for the transverse widening of large-span prestressed concrete continuous box girder bridges (main span ≥ 150m) at home and abroad, and there is no relevant research at all. The transverse widening of large-span prestressed concrete continuous box girder bridges (main span ≥ 150m) is different from that of small-span bridges. The transverse widening has the following problems:

[0009] 1. Influence of concrete shrinkage and creep

[0010] Due to the age difference between the new bridge and the old bridge, even if the segmental prefabricated cantilever assembly is used, it can only reduce the deformation caused by concrete shrinkage, but cannot reduce the influence of concrete creep. Therefore, the deformation of the new and old beam bridges is not synchronized. After the post-casting strip is used to widen and connect the whole, there must be tensile stress in the post-casting strip. This tensile stress will have an adverse effect on the post-casting strip. If it exceeds the material strength of the post-casting strip, it will tear the post-casting strip and produce visible cracks.

[0011] 2. Impact of uneven foundation settlement

[0012] For the spliced ​​bridge, the foundation settlement of the box girder of the newly built bridge has been basically completed, while the foundation settlement of the rebuilt bridge has not yet occurred because it has not been opened to traffic. If the foundation soil of the new box girder is not properly handled, resulting in excessive settlement, it will have an adverse effect on the superstructure of the widened bridge, resulting in a large additional force in the bridge beam, thus affecting the safe use of the structure.

[0013] 3. Influence of theoretical calculation and actual construction errors

[0014] After checking the operation of the long-span concrete continuous rigid frame bridges (main span ≥ 150m) that have been opened to traffic, it is found that this type of long-span bridge generally has a mid-span deflection that exceeds the theoretical calculated value. For example, the South China Bridge, a 110+190+110m prestressed concrete continuous rigid frame, was built in 1998. During the inspection in 2004, it was found that the mid-span deflection was 43mm, and there were through cracks in the web. It was strengthened by increasing external prestress, sticking steel plates on the inner side of the web, and paving UHPC ultra-high performance concrete on the top plate of the box girder to allow normal traffic; another example is the auxiliary navigation channel bridge of the Humen Bridge, a 150+270+150m prestressed concrete continuous rigid frame, built in 1999. During the inspection in 2004, it was found that the mid-span deflection of the left main span was 225mm, and it was strengthened by increasing external prestress. If the mid-span deflection is too large during actual operation, it will have an adverse effect on the widened post-cast strip and the main bridge, causing the post-cast strip to be easily damaged during operation, and the reinforcement design and construction of the post-cast strip itself are relatively difficult.

[0015] In summary, the transverse widening of large-span prestressed concrete continuous box girder bridges (main span ≥ 150m) will be affected by concrete shrinkage creep, uneven foundation settlement, construction errors, etc., resulting in large tensile stress in the widened post-cast strip, which puts the post-cast strip and the main bridge in an unfavorable stress state.

[0016] As shown in the previously disclosed patent CN110258289B, corrugated steel plates are used at the joints to improve the additional stress caused by uneven foundation settlement and concrete shrinkage creep in the splicing section, shorten the construction period and save costs; however, the corrugated steel plates are exposed to the outside and are easily corroded, which affects the service life and connection strength, and the corrugated steel plates and steel bars need to be welded and fixed one by one, which is a large and complicated welding workload, and the welding points are also easily corroded, which affects the connection reliability. Summary of the invention

[0017] The purpose of the present invention is to overcome the existing technical defects and provide a construction method for widening and splicing a large-span concrete bridge. The widening and reconstruction method of double-sided widening + transverse splicing is adopted to avoid the disadvantages of existing single-sided widening and double-sided widening, and the stress of the widened post-casting strip is within a reasonable range, thereby reducing the cost of subsequent maintenance.

[0018] In order to solve the above technical problems, the present invention provides another construction method for widening, splicing and reconstruction of a large-span concrete bridge, comprising the following steps:

[0019] S1. Build a first bridge and a second bridge on both sides of the original old bridge;

[0020] S2, demolish the old bridge;

[0021] S3. Reconstruct a third bridge and a fourth bridge at the site of the old bridge, with the third bridge adjacent to the first bridge and the fourth bridge adjacent to the second bridge;

[0022] S4: Close the outermost lanes on the sides adjacent to the first and third bridges, and close the outermost lanes on the sides adjacent to the second and fourth bridges;

[0023] S5. A skeleton steel structure is formed at the flanges on the adjacent sides of the first bridge and the third bridge and at the flanges on the adjacent sides of the second bridge and the fourth bridge, and the adjacent skeleton steel structures are connected and fixed by a prefabricated plate with corrugated steel embedded inside, and the prefabricated plate is located at the bottom of the skeleton steel structure;

[0024] S6. pouring high-strength concrete at the skeleton steel structure to form joints connecting the two bridges between the first bridge and the third bridge and between the second bridge and the fourth bridge, and the high-strength concrete and prefabricated panels cover the skeleton steel structure from top to bottom;

[0025] S7. Remove the closures on each bridge, so that the first bridge and the third bridge are connected to form a new one-way left bridge, and the second bridge and the fourth bridge are connected to form a new one-way right bridge.

[0026] Furthermore, in step S3, the flanges between the first bridge and the third bridge are 50 cm apart, and the flanges between the second bridge and the fourth bridge are 50 cm apart.

[0027] Furthermore, in step S4, the outermost lanes between adjacent bridges are closed by means of enclosure plates.

[0028] Furthermore, in step S5, the skeleton steel structure includes a steel plate extending along the length of the bridge and located at the lower end of the flange, one end of the steel plate is embedded in the bridge, the other ends of the steel plates on the two adjacent bridges are respectively extended toward each other and correspond to each other on the left and right, and the steel plates on the two adjacent bridges are connected and fixed by prefabricated plates to form a closed bottom surface when pouring concrete, the two ends of the prefabricated plates are respectively fixed to the bottom surfaces of the steel plates on the two bridges by bolts, and a gap is formed between the steel plates on the two adjacent bridges, and the middle protrusion of the prefabricated plate is provided with a trapezoidal bending portion placed at the gap.

[0029] Furthermore, the skeleton steel structure also includes a plurality of steel bars spaced along the length of the bridge and located at the upper end of the flange, one end of the steel bars is embedded in the bridge, and the other ends of the steel bars on two adjacent bridges are respectively extended toward each other and spaced alternately front and back.

[0030] Furthermore, one end of the steel bar extending out of the bridge is in a downward right angle shape, and the lower end of the steel bar abuts against the surface of the steel plate on the opposite flange.

[0031] Furthermore, the corrugated steel is made of weathering steel, and the surface of the corrugated steel is provided with an anti-corrosion coating.

[0032] Furthermore, in step S5, when prefabricated panels are used to connect adjacent skeleton reinforcement structures, a lifting device spanning the two bridges is first set up in a closed area on the two bridges, and then the prefabricated panels are lifted from bottom to top through the gap between the two bridges by the lifting device, so as to lift the prefabricated panels to the bottom of the skeleton reinforcement structure and fix them by bolts.

[0033] Furthermore, in step S6, the poured high-strength concrete is ultra-high performance concrete UHPC or ultra-strong and tough fiber concrete ECC.

[0034] Furthermore, after step S7, the following steps are also included:

[0035] S8. Build pedestrian paths and / or non-motorized vehicle lanes at the outermost lanes of one-way left bridges and one-way right bridges.

[0036] The present invention has the following beneficial effects:

[0037] 1. The bridge construction method of double-side widening + horizontal widening can make full use of the reserved space on both sides of the site, the center line of the road does not change relative to the original road, the road line is straight and smooth, and the scope of land acquisition and demolition can be minimized. After completion, the appearance of the bridge deck is two bridges, the bridge deck landscape effect is good, and there is no isolation in the same direction, which can facilitate traffic conversion; the new bridge (the first bridge and the second bridge) and the rebuilt bridge (the third bridge and the fourth bridge) use the same structural section form, and the new bridge (the first bridge and the second bridge) and the rebuilt bridge (the third bridge and the fourth bridge) are all new bridges, there is no difference between the old bridge and the new bridge, and the deflection difference caused by the different stiffness of the new and old bridges can be reduced, and the influence of concrete shrinkage creep at the joint when the new and old bridges are spliced ​​and the influence of uneven foundation settlement can be reduced.

[0038] 2. Use skeleton steel structure + precast panels with embedded corrugated steel as the pouring formwork. First, the corrugated steel inside the precast panel can enhance the deformation capacity of the joint to adapt to the different displacements and deformations of the two bridges. In addition, the corrugated steel is prefabricated inside the precast panel. First, it can avoid the problem of corrugated steel being corroded when it is outside. Second, it reduces the welding process and can be directly fixed with bolts, which is convenient for construction operations. The precast panel is located at the bottom of the skeleton steel structure. First, it can be used as the bottom closed formwork for pouring concrete, without the need to design scaffolding to form a pouring formwork. Second, the precast panel and the poured concrete jointly cover the skeleton steel structure to avoid corrosion of the skeleton steel structure and improve the structural life of the joint. The poured concrete uses UHPC ultra-high performance concrete or ultra-tough fiber concrete ECC, which has excellent tensile / compressive strength, toughness and durability. Studies have shown that the interface bonding performance between it and ordinary concrete is also excellent, which is suitable for splicing joints. The corrugated steel is made of weathering steel, and an anti-corrosion coating is applied on the surface during prefabrication.

[0039] 3. The method of setting up the prefabricated panels by lifting the hoisting device is simple and reliable, which saves the time and money of setting up scaffolding during construction, greatly shortens the construction period, saves costs, and is simple and quick to construct by connecting and fixing with the skeleton steel bars through lifting.

[0040] 4. The skeleton steel structure first uses steel plates extending along the length of the bridge to connect and fix with the prefabricated panels. First, it is convenient to connect with the prefabricated panels, and second, it can increase the structural strength of the connection. If ordinary steel bars are used, the spacing between the steel bars cannot be too small, the number of steel bars is large, and the amount of welding in the later stage is also large. If a whole piece of extended steel plate is used, the steel plate can be thicker, which is equivalent to full of steel bars, so the strength can be increased and the cracking of the widened joint can be prevented; right-angled steel bars are also provided at the upper end of the steel plate. The purpose is to increase the length of the steel bar fixing by extending the length of the steel bar to meet the length requirement of the fixing, thereby reducing the welding process of the steel bars in the two skeleton steel structures. In addition, the right-angled structure can also form a bending tensile force to improve the connection reliability at the joint.

[0041] 5. Considering that there will inevitably be errors in the elevation control when the new and old bridges are completed, if the joint is too narrow, it will be difficult to construct, and if the joint width is too wide, the construction will be complicated. Therefore, the joint width between the two bridges is controlled at about 50cm, which can facilitate construction and the construction process is simple and quick.

[0042] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0044] Figure 1 This is a schematic diagram of a first bridge and a second bridge newly built on both sides of an old bridge in an embodiment;

[0045] Figure 2 This is a schematic diagram of the demolition of the old bridge in the embodiment;

[0046] Figure 3 This is a schematic diagram of the reconstruction of the third bridge and the fourth bridge at the site of the old bridge in the embodiment;

[0047] Figure 4 This is a schematic diagram of using a hoisting device to lift a prefabricated panel in an embodiment;

[0048] Figure 5 It is a forward schematic diagram of the skeleton steel bar structure in the embodiment when it is connected by prefabricated panels;

[0049] Figure 6 It is a top view schematic diagram of the skeleton steel bar structure in the embodiment when it is connected by prefabricated panels;

[0050] Figure 7 A schematic diagram of the right-angle steel bars used in the skeleton steel bar structure in the embodiment;

[0051] Figure 8 It is a schematic diagram of pouring concrete between adjacent bridges to form joints in an embodiment. DETAILED DESCRIPTION

[0052] In order to more fully understand the technical content of the present invention, the present invention will be further introduced and explained in conjunction with the accompanying drawings and specific embodiments below; it should be noted that if there are descriptions such as "first", "second", etc. in the text, they are used to distinguish different components, etc., and do not represent the order of precedence, nor do they limit the "first" and "second" to be different types.

[0053] In the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0055] Example

[0056] In a specific implementation case, the existing bridge meets the Class III navigation standard, the main bridge span is (60+90+60)m, the main bridge adopts prestressed concrete continuous rigid frame, and the existing bridge is a double-span bridge with a total of six lanes in both directions. The reconstructed bridge needs to meet the Class I navigation standard, the main bridge span is (90+150+150+90)m, the double-span bridge has a total of ten lanes in both directions, and the main bridge also adopts prestressed concrete continuous rigid frame.

[0057] Specifically, the construction method for widening, splicing and reconstructing a large-span concrete bridge shown in this embodiment includes the following steps:

[0058] a. Figure 1 As shown, a first bridge 1 and a second bridge 2 are newly built on both sides of the original old bridge. After the two bridges are completed, they are open to traffic to meet the traffic relief requirements during the construction period; in a specific implementation case, the first bridge and the second bridge are both three lanes, thus forming a two-way six-lane structure.

[0059] b. The two-way traffic of the original old bridge is directed to the first bridge 1 and the second bridge 2 respectively, so as to use the first bridge and the second bridge to relieve traffic, while the original old bridge is closed.

[0060] c. Figure 2 As shown, the old bridge was demolished.

[0061] d. Figure 3 As shown, a third bridge 3 and a fourth bridge 4 are rebuilt on the site of the old bridge. The third bridge 3 is adjacent to the first bridge 1, and the fourth bridge 4 is adjacent to the second bridge 2. The third bridge and the fourth bridge are both three-lane bridges, so the four bridges are combined to form a two-way twelve-lane design.

[0062] Among them, the flanges between the first bridge 1 and the third bridge 3 are 50 cm apart, and the flanges between the second bridge 2 and the fourth bridge 4 are 50 cm apart; considering that there will inevitably be errors in elevation control when the new and old bridges are completed, it will be difficult to construct if the joint is too narrow, and the construction will be complicated if the joint width is too wide, so the joint width between the two bridges is controlled at about 50 cm, which can facilitate construction and the construction process is simple and quick.

[0063] e, such as Figure 3 As shown, the outermost lanes on the adjacent sides of the first bridge 1 and the third bridge 3 and the outermost lanes on the adjacent sides of the second bridge 2 and the fourth bridge 4 are closed by the enclosure plate 5, so that the joint construction is carried out in the closed lanes, while the unclosed lanes of the four bridges are open to traffic as usual, and the non-enclosed lanes of the third bridge and the fourth bridge are open to traffic as usual. In this way, there are four lanes for traffic in each direction, and one lane is added to the three lanes of a single bridge, thereby reducing the traffic impact caused by the enclosure construction.

[0064] f. Skeleton steel structures are formed at the flanges on the adjacent sides of the first bridge 1 and the third bridge 3, and at the flanges on the adjacent sides of the second bridge 2 and the fourth bridge 4. That is, when the four bridges are built, skeleton steel structures for later casting of splicing seams are formed at the flanges of the four bridges respectively, and adjacent skeleton steel structures are connected and fixed by prefabricated plates 9 with corrugated steel 7 embedded inside.

[0065] Among the above, Figure 4 As shown, when the precast plate 9 with the corrugated steel 7 embedded inside is used to connect the adjacent skeleton reinforcement structure, the lifting device 20 spanning the two bridges is first set up in the closed area on the two bridges, and then the precast plate 9 is lifted from bottom to top after passing through the gap between the two bridges by the lifting device 20, so as to lift the precast plate 9 to the bottom of the skeleton reinforcement structure and connect and fix it by bolts 10; the setting method of lifting the precast plate by the lifting device is simple and reliable, which saves time and money for setting up scaffolding during construction, greatly shortens the construction period, saves costs, and is connected and fixed with the skeleton reinforcement by lifting, so the construction is simple and fast.

[0066] In this embodiment, if Figure 5 and Figure 6 As shown, the skeleton steel structure includes a steel plate 8 extending along the length of the bridge and located at the lower end of the flange, one end of the steel plate 8 is embedded in the bridge, and the other ends of the steel plates 8 on the two adjacent bridges are respectively extended toward each other and correspond to each other on the left and right, and the steel plates on the two adjacent bridges are connected and fixed by a precast plate 9, the width of the precast plate 9 is adapted to the flange distance between the two adjacent bridges to form a closed bottom surface when pouring concrete, that is, a concrete precast plate with the same shape as the corrugated steel is first poured around the corrugated steel, so that the corrugated steel is located inside the precast plate, and then the two ends of the precast plate 9 are respectively fixed to the bottom surfaces of the steel plates 8 on the two bridges by bolts 10, and a gap is formed between the steel plates 8 on the two adjacent bridges, and the middle protrusion of the precast plate 9 is provided with a trapezoidal bending portion 91 placed at the gap.

[0067] As a preference, Figures 5 to 7 As shown, the skeleton steel bar structure also includes a plurality of steel bars 6 which are distributed at intervals along the length of the bridge and located at the upper end of the flange. One end of the steel bar 6 is pre-buried in the bridge, and the other ends of the steel bars 6 on the two adjacent bridges are respectively extended toward each other and distributed alternately at intervals front and back. After the steel bars 6 extend out of the bridge, they abut against the flange of the bridge on the opposite side, and one end of the steel bar 6 extending out of the bridge is in a right angle facing downward, and the lower end of the steel bar 6 abuts against the surface of the steel plate 8 on the flange on the opposite side. Firstly, the length of the steel bar is increased to the maximum extent, and secondly, the steel plate 8 is used to provide support for the steel bar on the opposite side, which can avoid the problem of deformation of the steel bar affecting the connection force.

[0068] Preferably, the corrugated steel is made of weathering steel, and the surface of the corrugated steel is provided with an anti-corrosion coating.

[0069] g. Figure 8 As shown, high-strength concrete is poured at the skeleton steel structure to form joints 30 connecting the two bridges between the first bridge 1 and the third bridge 3 and between the second bridge 2 and the fourth bridge 4, and the high-strength concrete and prefabricated panels cover the skeleton steel structure from top to bottom.

[0070] In the above, the poured high-strength concrete is ultra-high performance concrete UHPC or ultra-strong and tough fiber concrete ECC, which has excellent tensile / compressive strength, toughness and durability. Studies have shown that the interface bonding performance between it and ordinary concrete is also very excellent, and it is suitable for splicing joints.

[0071] h. Figure 8 As shown, the closures on each bridge are removed so that the first bridge 1 and the third bridge 3 are connected to form a new one-way left bridge, and the second bridge 2 and the fourth bridge 4 are connected to form a new one-way right bridge.

[0072] i. Build sidewalks and / or non-motorized vehicle lanes at the outermost lanes of the one-way left bridge and the one-way right bridge, so that the four bridges will eventually form a two-way ten-lane double-span bridge cross-section structure.

[0073] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A construction method for widening and splicing a large-span concrete bridge. It is characterized in that The following steps are involved: S1. Build a first bridge and a second bridge on both sides of the original old bridge; S2, demolish the old bridge; S3. Reconstruct a third bridge and a fourth bridge at the site of the old bridge, with the third bridge adjacent to the first bridge and the fourth bridge adjacent to the second bridge; S4: Close the outermost lanes on the sides adjacent to the first and third bridges, and close the outermost lanes on the sides adjacent to the second and fourth bridges; S5. A skeleton steel structure is formed at the flanges on the adjacent sides of the first bridge and the third bridge and at the flanges on the adjacent sides of the second bridge and the fourth bridge, and the adjacent skeleton steel structures are connected and fixed by a prefabricated plate with corrugated steel embedded inside, and the prefabricated plate is located at the bottom of the skeleton steel structure; The skeleton steel structure includes a steel plate extending along the length of the bridge and located at the lower end of the flange, one end of the steel plate is pre-buried in the bridge, the other ends of the steel plates on the two adjacent bridges are respectively extended toward each other and correspond to each other on the left and right, and the steel plates on the two adjacent bridges are connected and fixed by prefabricated plates to form a closed bottom surface when pouring concrete, the two ends of the prefabricated plates are respectively fixed to the bottom surfaces of the steel plates on the two bridges by bolts, and a gap is formed between the steel plates on the two adjacent bridges, and the middle protrusion of the prefabricated plate is provided with a trapezoidal bending portion placed at the gap; The skeleton steel structure also includes a plurality of steel bars distributed at intervals along the length of the bridge and located at the upper end of the flange, one end of the steel bar is pre-buried in the bridge, and the other ends of the steel bars on two adjacent bridges are respectively extended toward each other and are staggered at intervals in front and behind; S6. pouring high-strength concrete at the skeleton steel structure to form joints connecting the two bridges between the first bridge and the third bridge and between the second bridge and the fourth bridge, and the high-strength concrete and the precast panels cover the skeleton steel structure from top to bottom; S7. Remove the closures on each bridge, so that the first bridge and the third bridge are connected to form a new one-way left bridge, and the second bridge and the fourth bridge are connected to form a new one-way right bridge.

2. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that In step S3, the flanges between the first bridge and the third bridge are 50 cm apart, and the flanges between the second bridge and the fourth bridge are 50 cm apart.

3. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that In step S4, the outermost lanes between adjacent bridges are closed by means of enclosure plates.

4. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that One end of the steel bar extending out of the bridge is in a downward right angle shape, and the lower end of the steel bar abuts against the surface of the steel plate on the opposite flange.

5. A construction method for widening, splicing and reconstructing a long-span concrete bridge as described in any one of claims 1 to 4, It is characterized in that The corrugated steel is made of weathering steel, and the surface of the corrugated steel is provided with an anti-corrosion coating.

6. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that In step S5, when using prefabricated panels to connect adjacent skeleton steel structures, first set up a lifting device across the two bridges in a closed area on the two bridges, and then lift the prefabricated panels from bottom to top after passing through the gap between the two bridges through the lifting device, so as to lift the prefabricated panels to the bottom of the skeleton steel structure and fix them by bolts.

7. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that In step S6, the poured high-strength concrete is ultra-high performance concrete UHPC or ultra-strong and tough fiber concrete ECC.

8. The construction method for widening, splicing and reconstruction of a long-span concrete bridge as claimed in claim 1, It is characterized in that After step S7, the following steps are also included: S8. Build pedestrian paths and / or non-motorized vehicle lanes at the outermost lanes of one-way left bridges and one-way right bridges.

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