An aerial at-grade reinforcement structure for new and old bridges and its construction method

Abstract

This invention relates to a reinforcement structure for the intersection of a new and an old bridge in the air and its construction method, comprising: an extended corbel located below the side flange of the old bridge at the intersection of the new and old bridges, with its root connected to the newly constructed bridge; a new support platform placed below the central flange of the old bridge corresponding to the intersection of the new and old bridges, with its bottom being a pier; and a deformation buffer layer, which is respectively disposed between the extended corbel and the side flange of the old bridge, and between the new support platform and the central flange of the old bridge. This invention can solve the problem of insufficient flange bearing capacity of the old bridge when a new bridge intersects the old bridge perpendicularly in the air, and can avoid defects such as voids and incomplete compaction between the new support platform and the existing flange, ensuring the structural integrity of the new support platform and the existing flange, and reserving deformation space between the new support platform and the existing flange.

Description

Technical Field

[0001] This invention relates to a building structure and its construction method, particularly a bridge building structure and its construction method, specifically a bridge at-grade crossing reinforcement structure for new and old bridges and its construction method. Background Technology

[0002] With the rapid development of high-grade highways and urban viaducts in my country, bridge construction has made breakthrough progress. This has led to numerous situations where newly built viaducts need to intersect with existing viaducts at ground level, such as new bridges intersecting perpendicularly with old ones. In these cases, the intersection of the new and old bridges alters the original vehicle load-bearing method of the old bridge, easily causing problems such as the deflection at the cantilever ends of the old bridge deck exceeding the specified limits and inconsistencies in deformation between the new and newly constructed sections.

[0003] Currently, conventional methods for reinforcing old bridges mainly involve bonding steel plates and carbon fiber fabric to the bottom and flanges of the box girders. Specifically:

[0004] 1) The old bridge's box girder bottom slab was reinforced with longitudinally bonded steel plates and secured with chemical anchors in the mid-span area to enhance its mid-span bending capacity. Longitudinally bonded steel plates and bolted steel strips were also used to fix the web within a certain range on both sides of the bridge abutment centerline and pier centerline to enhance its shear capacity. The reinforcing steel plates were made of Q235 or Q345 hot-rolled flat steel strips, directly bonded with adhesive, and fixed to the box girder with chemical anchors.

[0005] 2) Reinforcement of the old bridge flange plates with carbon fiber cloth, spaced along the longitudinal direction of the old bridge. The cloth is directly glued to the underside of the old bridge flanges and secured with long pressure strips. The pressure strips are also made of carbon fiber cloth and are spaced along the transverse direction of the old bridge.

[0006] The aforementioned conventional methods of reinforcing old bridges, such as bonding steel plates and carbon fiber cloth, can fully utilize the existing bridge's load-bearing capacity and leverage the strength and stiffness of the steel plates and carbon fiber cloth to further enhance its ultimate load-bearing capacity. However, when a new bridge intersects an old bridge perpendicularly, creating a non-parallel connection, new traffic patterns are formed. This significantly impacts the load-bearing capacity of the old bridge structure due to varying vehicle loads. Consequently, the bending and shear capacity of the bridge deck flanges after conventional reinforcement may still be insufficient to meet the needs of safe passage. Therefore, new structures and construction methods need to be designed for at-grade intersections of new and old bridges to better meet market demands. Summary of the Invention

[0007] The purpose of this invention is to address the problems encountered when new and old bridges intersect at elevated levels by providing a reinforcement structure and construction method for such intersections. This method utilizes extended corbels and new support platforms to reinforce the flanges of the old bridge, providing sufficient load-bearing capacity. Furthermore, by setting up a deformation buffer layer, it effectively eliminates problems such as voids, incomplete compaction, and inconsistent deformation between the extended corbels / new support platforms and the bottom of the existing old bridge flanges, thereby improving the quality of the new and old bridge intersections at elevated levels.

[0008] The technical solution of this invention is:

[0009] An aerial at-grade reinforcement structure for new and old bridges includes:

[0010] The extended corbel is located below the side flange of the old bridge at the intersection of the old and new bridges, and its root is connected to the newly built bridge.

[0011] The newly added support platform is placed below the center flange of the old bridge at the intersection of the old and new bridges, and its bottom is the bridge pier;

[0012] Deformation buffer layer; the deformation buffer layer is respectively disposed between the extended corbel and the side flange of the old bridge, and between the newly added support platform and the center flange of the old bridge; the deformation buffer layer includes multiple spaced rubber strips; foam boards are provided between adjacent rubber strips.

[0013] Furthermore, the newly added support platform is rectangular and is set along the direction of the old bridge.

[0014] Furthermore, the rubber strips are arranged in parallel at equal intervals.

[0015] Furthermore, the rubber strip is arranged laterally along the old bridge and the extended corbel.

[0016] Furthermore, a thin layer of foam is provided at the bottom of the rubber strip.

[0017] Furthermore, the thickness of the foam board is comparable to that of the rubber strip after the foam layer has been applied.

[0018] Furthermore, a W-shaped expansion joint is provided between the side flange of the old bridge and the new bridge.

[0019] A construction method for reinforcing an elevated intersection of old and new bridges includes the following steps:

[0020] 1) Construct pile foundations below the center flange of the old bridge at the center line location, and construct pile-column piers above the pile foundations;

[0021] 2) Erect full-span scaffolding at the locations of the newly added support platform and extended corbels, and lay the bottom formwork flush with the lower surface of the newly added support platform and extended corbel structure;

[0022] 3) Arrange and attach strip rubber strips longitudinally and laterally below the center flange of the old bridge corresponding to the new support platform and the side flange of the old bridge corresponding to the extended corbel; attach a thin layer of foam below the strip rubber strips; attach foam boards in the area between the strip rubber strips;

[0023] 4) The pedestrian walkway at the intersection of the old and new bridges in the air was removed; multiple pouring holes with a diameter of 10cm were opened on the center flange of the old bridge above the new support platform and on the side flange of the old bridge above the extended corbel, penetrating the old bridge deck and avoiding the original main reinforcement and prestressed steel strands in the old bridge.

[0024] 5) After the reinforcement of the new support platform and the extended corbel is completed and the side formwork is reinforced, the pump pipe is used to penetrate into the interior through the pouring hole to pour self-compacting concrete; the pouring of concrete for the new support platform and the extended corbel is stopped after it reaches the top of the pouring hole.

[0025] 6) After the concrete has been cured for 28 days, core samples were taken from the pouring holes for inspection. Core samples were taken to the bottom of the side flange and the center flange of the old bridge. After the core samples were taken for inspection, rubber sheets were placed at the bottom of the pouring holes and the holes were filled with self-compacting concrete to level the surface of the old bridge.

[0026] 7) A W-shaped expansion joint shall be installed between the side flange of the old bridge at the intersection of the new bridge and the level bridge.

[0027] Furthermore, in step 3), the spacing between the strip rubber strips is 20cm.

[0028] The beneficial effects of this invention are:

[0029] This invention strengthens the flange plates of an old bridge by adding extended corbels and new support platforms, significantly improving the bending and shear strength of the old bridge flange deck, fully meeting the load-bearing requirements of new traffic patterns. Simultaneously, it effectively solves problems such as voids, incomplete compaction, and inconsistent deformation between the extended corbels / new support platforms and the bottom of the existing old bridge flange. It not only effectively connects the existing old bridge flange plates, deformation buffer layer, and new abutment to form a complete load-bearing system, ensuring dense and seamless filling of the existing flange bottom, but also features simple and quick on-site construction, improving the construction quality of the elevated intersection of the old and new bridges. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the cross-section of the aerial reinforcement structure of the old and new bridges.

[0031] Figure 2 This is a schematic diagram of the longitudinal section of the aerial cross-section reinforcement structure of the old and new bridges.

[0032] Figure 3 This is a schematic diagram of the aerial reinforcement structure for the old and new bridges.

[0033] Figure 4 This is a detailed drawing of the reinforcement of the centerline flange of the old bridge.

[0034] Figure 5 yes Figure 4 Sectional view of AA.

[0035] Figure 6 yes Figure 4 BB section view.

[0036] Figure 7 This is a detailed drawing of the flange reinforcement at the junction of the old and new bridges.

[0037] Figure 8 yes Figure 7 CC section view.

[0038] Figure 9 yes Figure 7 DD section view.

[0039] Among them, 1-Old bridge side flange; 2-Pedestrian walkway slab; 3-Deformation buffer layer; 4-New support platform; 5-Bridge pier; 6-Pile foundation; 7-New bridge; 8-Outward corbel; 9-W-type expansion joint; 10-Pouring hole; 11-Old bridge center flange; 31-Strip rubber strip; 32-Foam board; 33-Foam thin layer. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] The following description of the embodiments is merely for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0042] This invention provides a reinforcement structure for the intersection of new and old bridges in the air and its construction method. It can solve the problem of insufficient bearing capacity of the flange of the old bridge when the new bridge intersects the old bridge perpendicularly in the air. It can also avoid the occurrence of voids and incomplete pouring between the new support platform and the existing flange, ensure the structural integrity of the new support platform and the existing flange, and reserve deformation space between the new support platform and the existing flange.

[0043] See Figure 1 , Figure 2 , Figure 3 As shown, the first aspect of the present invention provides an aerial level crossing reinforcement structure for new and old bridges, including a newly added support platform and an extended corbel, etc.

[0044] The newly added support platform 4 is a rectangular structure located below the central flange 11 of the old bridge at the intersection of the old and new bridges, and is arranged longitudinally along the old bridge. A deformation buffer layer 3 is also provided between the central flange 11 of the old bridge and the newly added support platform 4 to fill the gap between the central flange 11 of the old bridge and the newly added support platform 4, which can prevent the old bridge from cracking or being damaged due to a hard connection between the central flange 11 of the old bridge and the newly added support platform 4.

[0045] The newly added support platform 4 is a cast-in-place reinforced concrete solid slab, with a pier 5 at its base. The pile-column pier 5 is supported by pile foundations 6. The newly added support platform 4 and the pile-column pier 5, as well as the pile-column pier 5 and the pile foundation 6, are all connected by steel bars.

[0046] The extended corbel 8 is located below the side flange 1 of the old bridge at the intersection of the old and new bridges. Its root is rigidly connected to the new bridge, providing support for the side flange of the old bridge. A deformation buffer layer 3 is also provided between the side flange 1 of the old bridge and the extended corbel 8 to fill the gap between them, preventing damage to the old bridge caused by the rigid connection between the side flange 1 and the extended corbel 8.

[0047] To facilitate the at-grade intersection of the old and new bridges, the pedestrian walkway slab 2 of the old bridge needs to be removed, and a W-shaped expansion joint 9 needs to be installed between the side flange 1 of the old bridge and the intersection point of the new bridge 7.

[0048] Both the newly added support platform 4 and the extended corbel 8 are constructed using self-compacting concrete. To facilitate pouring, multiple pouring holes 10 are provided on the side flange 1 and the center flange 11 of the old bridge. These pouring holes 10 penetrate the old bridge deck but avoid the existing main reinforcement and prestressed steel strands within the old bridge, allowing the self-compacting concrete to be poured through these holes into the molds of the new support platform and extended corbel, ensuring complete pouring. Preferably, the diameter of the pouring hole 10 is approximately 10 cm.

[0049] See Figures 4-9 As shown, the deformation buffer layer 3 is located between the newly added support platform 4 and the center flange 11 of the old bridge, and between the extended corbel 8 and the side flange 1 of the old bridge. This deformation buffer layer 3 consists of strip rubber strips 31, foam boards 32, and thin foam layers 33. The strip rubber strips 31 are made of neoprene rubber, 20cm wide and 4cm thick, and are spaced 20cm apart longitudinally along the old bridge. The transverse bonding of the strip rubber strips prevents compaction between the concrete of the newly added support platform 4 and the center flange 11 of the old bridge, and between the concrete of the extended corbel 8 and the side flange 1 of the old bridge, ensuring deformation buffer space. Simultaneously, because the deformation values ​​of the long sides of the side flanges and extended corbels of the old bridge are relatively large, the strip rubber strips are arranged transversely along the old bridge and extended corbels to fully utilize the deformation capacity of the deformation buffer layer, and the spacing between adjacent rubber strips provides space for future deformation.

[0050] The foam board 32 fills the area between adjacent strip rubber strips 31. The foam board 32 is 20cm wide and 4cm thick, which prevents the concrete pouring for the new support platform and extended corbels from affecting the deformation buffer layer due to the filling of the gaps between the strip rubber strips, and ensures the flatness of the top of the new support platform and extended corbels. Furthermore, the foam board is lightweight and has a large deformation capacity, which not only significantly reduces the additional load but also fully meets the deformation requirements of the rubber strips.

[0051] The foam thin layer 33 is about 2mm thick and is pasted below the strip rubber strip 31. The thickness of the strip rubber strip with the foam thin layer pasted on it is equivalent to the thickness of the foam board. This can prevent the concrete of the newly added support platform and the extended bracket from sticking to the strip rubber strip during the pouring, thus avoiding the impact on the deformation capacity.

[0052] Furthermore, the width and spacing of the strip rubber strips need to be determined through structural analysis and modeling calculations based on the stress state of the old bridge flange under the new traffic conditions, so as to meet the old bridge flange support requirements and the deformation difference between the shrinkage and creep of the old and new concrete.

[0053] The reinforcement structure of the present invention can effectively connect the existing old bridge flange plate, deformation buffer layer 3, newly added support platform 4 and outward bracket 8 to form a complete force system, which can ensure that the bottom of the old bridge side flange 1 and the old bridge center flange 11 is filled densely and without dead corners, and the on-site construction process is simple and quick.

[0054] See Figures 1-9 As shown, the second aspect of this application provides a construction method for reinforcing an overhead intersection of old and new bridges, the method comprising the following steps:

[0055] At the location of the old bridge's centerline, below the center flange of the old bridge, pile foundation 6 was constructed. Conventional impact drilling was used to form the holes, and the pile position, pile diameter, and elevation were strictly controlled.

[0056] Before the construction of the pile-column pier 5, the loose concrete at the top of the pile foundation 6 is roughened and leveled, and loose gravel, laitance and other impurities are removed. Low-strain and high-strain dynamic tests are then conducted.

[0057] Pier 5 is connected to pile foundation 6 by steel bars. The outer formwork of pier 5 is made of customized semi-circular bamboo plywood, which is fixed with binding straps. Diagonal steel pipe supports are set around the perimeter to reinforce the outer formwork.

[0058] A full-span fastener-type scaffolding is erected at the locations of the newly added support platform 4 and the extended corbel 8. A bottom formwork is laid on top of the scaffolding, which is flush with the lower surface of the newly added support platform 4 and the extended corbel 8.

[0059] Use an angle grinder to smooth the concrete base surface at the bottom of the side flanges and center flange of the old bridge, removing surface laitance, oil stains, and other impurities until the new concrete structure is completely exposed. Use an air compressor to blow away the dust until it is no longer sticky to the touch. Lay out and mark the outline of the reinforcement bonding positions for the lower part of the side flange 1 and center flange 11 of the old bridge.

[0060] Newly added support platform 4 and extended corbel 8 are fitted with horizontal strips of rubber 31 along the side flanges and center flange of the old bridge, with one strip every 20cm along the longitudinal direction of the old bridge. The strips of rubber 31 are made of neoprene rubber and were pre-made by the manufacturer.

[0061] Before using the adhesive for bonding the deformation buffer layer 3, a quality inspection must be conducted. Only adhesives that pass the inspection can be used. Prepare the adhesive according to the product instructions, stirring in the same direction to avoid air bubbles. Prevent water from entering the container during stirring.

[0062] Apply the adhesive tightly and evenly with a scraper to the concrete bonding surfaces of the side flanges and center flanges of the old bridge, which have undergone surface cleaning, ensuring it is fully saturated. The adhesive application section should be triangular, with a thickness of 3-5 mm in the center and thinner application on the sides. Align the strip rubber 31 with the pre-marked bonding surface of the old bridge and quickly press it to ensure a tight bond between the strip rubber 31 and the bonding surface, squeezing out any excess adhesive.

[0063] Fill the 20cm interval between adjacent rubber strips 31 with foam board 32, with a thickness of not less than 4cm. The installation method is the same as for the rubber strips 31.

[0064] After the foam board 32 in the spacer area of ​​the strip rubber strip 31 is pasted, a thin foam layer 33 with a thickness of 2mm is pasted below the strip rubber strip 31.

[0065] After the deformation buffer layer 3 is completed, a crusher, electric hammer, and manual labor are used to remove the old bridge pedestrian walkway slab 2 at the aerial intersection of the old and new bridges. A drilling machine is used to drill multiple 10cm diameter holes through the old bridge deck on the side and center flanges of the new supporting platform 4 and the extended corbel 8. The drilling is perpendicular to the concrete surface of the old bridge deck. Drilling should begin slowly, and then proceed at full speed once the drill bit is stable. Vibration during drilling should be minimized to prevent edge breakage.

[0066] Before drilling, a rebar detector must be used to measure the position of the existing rebars and steel strands in the side flanges and center flanges of the old bridge to ensure that drilling will not damage the main reinforcement and the steel strands of the bridge deck.

[0067] Operators were positioned at the top of the full-span scaffolding to carry out the reinforcement binding of the new support platform 4 and the extended corbel 8, as well as the side formwork reinforcement. Before concrete pouring, the formwork support and reinforcement were inspected. The concrete pump pipe extended into the pouring hole 10 to pour self-compacting concrete. The concrete pouring of the new support platform 4 and the extended corbel 8 was stopped after reaching the top of the pouring hole 10.

[0068] After 28 days of concrete curing, when it reaches 100% strength, core samples were taken from pouring hole 10 for inspection. Core samples were taken to the bottom of the side flange 1 and the center flange 11 of the old bridge. After the core samples were inspected and the strength was confirmed to meet the design requirements, a rubber sheet was placed at the bottom of pouring hole 10, and self-compacting concrete was refilled to level it with the old bridge deck. This prevents damage to the old bridge from the hard connection between the newly added support platform and the overhanging corbel at the location of pouring hole 10 and the old bridge.

[0069] Remove the full-span fastener-type scaffolding at the locations of the newly added support platform 4 and the extended corbel 8.

[0070] A W-shaped expansion joint 9 is installed between the newly constructed bridge 7 and the side flange 1 of the old bridge. This W-shaped expansion joint 9 is a complete product manufactured by the manufacturer, and the flatness and elevation of the concrete within the range of the W-shaped expansion joint 9 and the expansion joint itself are controlled by the asphalt concrete pavement layer of the newly constructed bridge 7. After installation, the joint surface of the W-shaped expansion joint 9 is flat, the longitudinal and transverse slopes meet the design requirements, and it smoothly connects with the asphalt concrete pavement of the newly constructed bridge 7 and the side flange 1 of the old bridge.

[0071] All parts not covered in this invention are the same as or can be implemented using existing technologies.

Claims

1. A new and old bridge overpass air reinforcement structure, characterized in that, The utility model relates to a kind of old bridge and new bridge crossing structure, including: Overhanging bracket, the lower side of the old bridge flange at the position where new and old bridge crossing, its root is connected with newly-built bridge; Newly-added supporting platform, placed in the lower side of the old bridge center flange at the position where new and old bridge crossing, its bottom is bridge pier; Deformation buffer layer; The deformation buffer layer is respectively arranged between the overhanging bracket and the old bridge flange, and between the newly-added supporting platform and the old bridge center flange;The deformation buffer layer includes multiple rubber strips arranged at intervals;Foam board is arranged between adjacent rubber strips; The rubber strips are arranged equidistantly and parallelly;The rubber strips are arranged along the transverse direction of the old bridge and the overhanging bracket;The bottom of the rubber strips is provided with a foam layer.

2. The new and old bridge overpass reinforcing structure according to claim 1, characterized in that, The newly-added supporting platform is a rectangular body, and is arranged along the longitudinal direction of the old bridge.

3. The new and old bridge overpass reinforcing structure according to claim 1, characterized in that, The thickness of the foam board is equivalent to that of the rubber strip with the foam layer.

4. The new and old bridge overpass reinforcing structure according to claim 1, characterized in that, A W-shaped expansion joint is arranged between the old bridge flange and the newly-built bridge.

5. The construction method of the new and old bridge overpass reinforcement structure in the air according to any one of claims 1-4, characterized in that, The utility model includes the following steps: 1) pile foundation is constructed under the old bridge center flange at the position of the old bridge center line, and pile column type bridge pier is constructed on the upper part of the pile foundation; 2) full-frame support is erected at the position of the newly-added supporting platform and the overhanging bracket, and bottom mold is laid to be flush with the lower surface of the newly-added supporting platform and the overhanging bracket structure; 3) strip-shaped rubber strips are arranged along the longitudinal direction of the old bridge and pasted transversely under the old bridge center flange corresponding to the newly-added supporting platform and the old bridge flange corresponding to the overhanging bracket;A foam layer is pasted under the strip-shaped rubber strips;Foam board is pasted between the strip-shaped rubber strips; 4) the footway board at the position where the new and old bridge cross in the air is removed, a plurality of pouring holes are formed on the old bridge center flange above the newly-added supporting platform and the old bridge flange above the overhanging bracket, the hole diameter is 10 cm, the pouring holes penetrate the old bridge deck, and the pouring holes avoid the original main reinforcement and prestressed steel strands in the old bridge; 5) after the reinforcement binding and side mold reinforcement of the newly-added supporting platform and the overhanging bracket are completed, pump pipe is used to pour self-compacting concrete from the pouring holes;The pouring of the self-compacting concrete is stopped after the concrete of the newly-added supporting platform and the overhanging bracket is poured to the top of the pouring holes; 6) after the concrete is cured for 28 days, the pouring holes are cored and inspected;The core is taken to the bottom of the old bridge flange and the old bridge center flange;After the core inspection, rubber sheets are placed at the bottom of the pouring holes, and self-compacting concrete is filled again to level the old bridge deck; 7) a W-shaped expansion joint is arranged between the newly-built bridge and the old bridge flange at the crossing position.

6. The construction method of the new and old bridge overpass reinforcing structure according to claim 5, characterized in that, In step 3), the distance between the strip-shaped rubber strips is 20 cm.

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