A longitudinal expansion joint structure suitable for old bridge widening

Abstract

The utility model provides a kind of longitudinal expansion joint structure suitable for old bridge wide, old bridge box girder roof and new bridge box girder roof flush setting and being equipped with wide joint between two, the side of old bridge box girder roof close to wide joint is equipped with steel framework and the steel framework is connected with old bridge reinforcement framework in old bridge box girder roof, the side of new bridge box girder roof close to wide joint is equipped with steel framework and the steel framework is connected with new bridge reinforcement framework in new bridge box girder roof, two steel frameworks are equipped with elastomer and corrugated sheet;The steel framework on the old bridge box girder roof and the asphalt surface layer on the old bridge box girder roof between and the steel framework on the new bridge box girder roof and the asphalt surface layer on the new bridge box girder roof between are all equipped with cast-in-place concrete layer.The longitudinal expansion joint structure of the utility model, corrugated sheet can be deformed together with elastomer, can be well buffered, absorb the vibration generated by vehicle driving, improve the comfort of vehicle driving.

Description

Technical Field

[0001] This utility model relates to the field of bridge engineering technology, specifically to a longitudinal expansion joint structure suitable for widening old bridges. Background Technology

[0002] The rise in economic levels has led to frequent population and goods flows, resulting in a sharp increase in transportation demand. Existing lines are unable to meet this growing demand, making the reconstruction and expansion of highways and municipal roads an inevitable trend. Bridges, as a significant component of modern roads, have seen widening designs become a key focus as highway and municipal road reconstruction and expansion continue. Reinforced concrete box girders are a commonly used structural form in bridge engineering, widely applied in urban overpasses and interchanges.

[0003] When widening existing and new reinforced concrete box girder bridges, conventional expansion joints are rigid while the asphalt pavement on both sides is flexible. This type of connection results in poor driving comfort. Therefore, a longitudinal expansion joint structure suitable for widening existing bridges is needed, where both the expansion joint itself and the asphalt pavement on both sides are flexible, thereby improving driving comfort. Utility Model Content

[0004] The purpose of this utility model is to provide a longitudinal expansion joint structure suitable for widening old bridges, aiming to solve the problem of existing rigid expansion joints affecting driving comfort when connected to flexible asphalt pavement layers. The specific technical solution is as follows:

[0005] A longitudinal expansion joint structure suitable for widening old bridges is provided, wherein the top plates of the old bridge box girder and the new bridge box girder are flush and a widening joint is provided between them. The top plate of the old bridge box girder is provided with a steel frame on the side near the widening joint and the steel frame is connected to the old bridge steel reinforcement frame in the top plate of the old bridge box girder. The top plate of the new bridge box girder is provided with a steel frame on the side near the widening joint and the steel frame is connected to the new bridge steel reinforcement frame in the top plate of the new bridge box girder. An elastic body and a corrugated plate are provided between the two steel frames.

[0006] A cast-in-place concrete layer is provided between the steel frame on the top slab of the old bridge box girder and the asphalt surface layer on the top slab of the old bridge box girder, and between the steel frame on the top slab of the new bridge box girder and the asphalt surface layer on the top slab of the new bridge box girder.

[0007] Preferably, the steel frame includes a flange plate and a web plate, the web plate is disposed on the flange plate and the two form a T-shaped structure, the side of the flange plate with the web plate is fitted with the elastomer, and the web plate extends into the interior of the elastomer.

[0008] Preferably, two steel frames are connected to both sides of the corrugated plate, and the corrugated plate is disposed inside the elastic body or at the bottom of the elastic body.

[0009] Preferably, a portion of the old bridge steel reinforcement skeleton is located in the top slab of the old bridge box girder, and another portion is located in the cast-in-place concrete layer on the top slab of the old bridge box girder, and this portion is connected to the steel skeleton on the top slab of the old bridge box girder.

[0010] A portion of the steel reinforcement skeleton of the new bridge is located in the top slab of the new bridge box girder, and another portion is located in the cast-in-place concrete layer on the top slab of the new bridge box girder, and this portion is connected to the steel skeleton on the top slab of the new bridge box girder.

[0011] Preferably, the old bridge steel reinforcement cage includes old bridge steel cage units and cast-in-place longitudinal reinforcement. A portion of the old bridge steel cage unit is located in the top slab of the old bridge box girder, and another portion is located in the cast-in-place concrete layer and is connected to the steel cage through this portion. Multiple old bridge steel cage units are spaced apart along the longitudinal direction of the bridge and are connected in series through cast-in-place longitudinal reinforcement in the cast-in-place concrete layer.

[0012] Preferably, the old bridge steel frame unit includes guardrail embedded steel bars and cast-in-place layer transverse steel bars; the guardrail embedded steel bars are U-shaped and are set in the top plate of the old bridge box girder, one end of the guardrail embedded steel bars is located below the elastic body and flush with the upper surface of the top plate of the old bridge box girder, and the other end extends into the cast-in-place concrete layer; the cast-in-place layer transverse steel bars are set in the cast-in-place concrete layer, one end of which is connected to the end of the guardrail embedded steel bars located in the cast-in-place concrete layer, and the other end is connected to the steel frame, and the cast-in-place layer longitudinal steel bars are connected to the cast-in-place layer transverse steel bars.

[0013] Preferably, the old bridge steel frame unit further includes vertical rebars. The lower part of the vertical rebars is set in the top plate of the old bridge box girder and the lower end is connected to the pre-embedded steel bars of the guardrail. The upper part is set in the cast-in-place concrete layer and connected to the transverse steel bars of the cast-in-place layer. The upper part of the vertical rebars is also connected to the steel frame through anchor plates.

[0014] Preferably, the new bridge steel reinforcement cage includes new bridge steel frame units and new bridge top plate longitudinal reinforcement. The new bridge steel frame units are located in the new bridge box girder top plate, with a portion located in the cast-in-place concrete layer and connected to the steel frame through this portion. Multiple new bridge steel frame units are spaced apart along the longitudinal direction of the bridge and are connected in series with each new bridge steel frame unit through the new bridge top plate longitudinal reinforcement in the new bridge box girder top plate.

[0015] Preferably, the new bridge steel frame unit includes box girder facade stirrups, embedded vertical reinforcement bars, and new bridge top slab transverse reinforcement bars; both the box girder facade stirrups and the new bridge top slab transverse reinforcement bars are located in the new bridge box girder top slab, the box girder facade stirrups are located below the new bridge top slab transverse reinforcement bars, and the end of the box girder facade stirrups near the splice joint is bent and connected to the end of the new bridge top slab transverse reinforcement bars, the new bridge top slab transverse reinforcement bars are connected to the new bridge top slab longitudinal reinforcement bars; the lower part of the embedded vertical reinforcement bars is located in the new bridge box girder top slab and is connected to the box girder facade stirrups and the new bridge top slab transverse reinforcement bars in sequence, and the upper part is located in the cast-in-place concrete layer and is connected to the steel frame through anchor plates.

[0016] Preferably, the lower end of the pre-embedded vertical steel bar is bent and connected to the stirrups on the facade of the box girder.

[0017] The application of the technical solution of this utility model has the following beneficial effects:

[0018] The longitudinal expansion joint structure of this utility model only requires cutting off a portion of the asphalt surface layer near the joint of the old bridge to complete the construction of the longitudinal expansion joint, reducing the damage to the old bridge and improving the construction efficiency of the longitudinal expansion joint structure. At the same time, the steel frames on both sides are connected to the steel reinforcement frames of the new bridge and the old bridge respectively. After the construction of the elastic body and the cast-in-place concrete layer, the new and old bridge bodies form an integral structure. Both the elastic body and the asphalt surface layer are flexible, which greatly improves the driving comfort.

[0019] The longitudinal expansion joint structure of this utility model has a corrugated plate connected between the steel frames on both sides. The corrugated plate can deform together with the elastic body, which can effectively buffer and absorb the vibration generated by vehicle driving and improve the comfort of vehicle driving.

[0020] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the figures. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the structure of the old bridge after it has been widened in this utility model;

[0023] Figure 2 It is the first type of longitudinal expansion joint structure in Figure 1 Cross-sectional view at point A in the middle;

[0024] Figure 3 It is the second type of longitudinal expansion joint structure inFigure 1 Cross-sectional view at point A in the middle;

[0025] Among them, 1. Top slab of old bridge box girder, 2. Top slab of new bridge box girder, 3. Steel frame, 4. Elastomer, 5. Corrugated plate, 6. Anchor plate, 7. Cast-in-place concrete layer, 8. Asphalt surface layer, 9. Reinforcing steel frame of old bridge, 9.1. Embedded reinforcing steel of guardrail, 9.2. Vertical rebar, 9.3. Longitudinal reinforcing steel of old bridge top slab, 9.4. Transverse reinforcing steel of cast-in-place layer, 9.5. Longitudinal reinforcing steel of cast-in-place layer, 10. Reinforcing steel frame of new bridge, 10.1. Stirrups on the facade of box girder, 10.2. Embedded vertical reinforcing steel, 10.3. Transverse reinforcing steel of new bridge top slab, 10.4. Longitudinal reinforcing steel of new bridge top slab, 11. Wide joint. Detailed Implementation

[0026] To facilitate understanding of this invention, a more comprehensive description is provided below, along with preferred embodiments. However, this invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0028] Example 1:

[0029] See Figure 1 and Figure 2 This embodiment provides a longitudinal expansion joint structure suitable for widening old bridges. The top plate 1 of the old bridge box girder and the top plate 2 of the new bridge box girder are set flush and a widening joint 11 (i.e., gap) is provided between them. The top plate 1 of the old bridge box girder is provided with a steel frame 3 on the side near the widening joint 11 and the steel frame 3 is connected to the old bridge steel reinforcement frame 9 in the top plate 1 of the old bridge box girder. The top plate 2 of the new bridge box girder is provided with a steel frame 3 on the side near the widening joint 11 and the steel frame 3 is connected to the new bridge steel reinforcement frame 10 in the top plate 2 of the new bridge box girder. An elastic body 4 and a corrugated plate 5 are provided between the two steel frames 3. The elastic body 4 and the corrugated plate 5 are located above the widening joint 11 and the length of the elastic body and the corrugated plate is the same as the length of the widening joint.

[0030] A cast-in-place concrete layer 7 is provided between the steel frame on the top plate 1 of the old bridge box girder and the asphalt surface layer 8 on the top plate 1 of the old bridge box girder, and between the steel frame on the top plate 2 of the new bridge box girder and the asphalt surface layer 8 on the top plate 2 of the new bridge box girder.

[0031] Specifically, the steel frame 3 includes a flange plate and a web plate. The web plate is disposed on the flange plate, and the two form a T-shaped structure. The side of the flange plate with the web plate is fitted with the elastomer 4, and the web plate extends into the interior of the elastomer 4. Furthermore, the web plate, flange plate, and elastomer are preferably bonded together.

[0032] Preferably, the material of the elastomer 4 includes, but is not limited to, one or a combination of two or more of the following: thermosetting modified epoxy resin, thermosetting polyurethane resin, thermosetting modified silicone resin, thermosetting modified acrylic resin, thermoplastic elastomers (including styrene-based, olefin-based, diene-based, vinyl chloride-based, and polyurethane-based), and vulcanized rubber. The use of flexible materials in the elastomer can significantly reduce vibrations from vehicle traffic, and the appearance and color of the elastomer can be consistent with the asphalt surface layer 8, ensuring color uniformity. Furthermore, the elastomer 4 can be cast on-site or prefabricated.

[0033] Preferably, two steel frames 3 are connected to both sides of the corrugated plate 5. In this embodiment, the corrugated plate 5 is disposed at the bottom of the elastic body 4, and the two ends of the corrugated plate are respectively connected to two flange plates. Figure 2 As shown. The material of the corrugated plate 5 includes, but is not limited to, galvanized steel plate, cold-rolled steel plate, stainless steel plate, aluminum alloy plate, or rigid plastic. The deformation of the corrugated plate can buffer and absorb vibrations, ensuring the comfort of the vehicle when driving at the expansion joint.

[0034] like Figure 2 As shown, a portion of the old bridge steel reinforcement skeleton 9 is located in the top slab 1 of the old bridge box girder, and another portion is located in the cast-in-place concrete layer 7 on the top slab 1 of the old bridge box girder, and this portion is connected to the steel skeleton 3 on the top slab 1 of the old bridge box girder.

[0035] Specifically, the old bridge steel reinforcement frame 9 includes old bridge steel frame units and cast-in-place longitudinal reinforcement 9.5. Part of the old bridge steel frame unit is located in the top plate 1 of the old bridge box girder, and another part is located in the cast-in-place concrete layer 7 and is connected to the steel frame 3 through this part. Multiple old bridge steel frame units are arranged at intervals along the longitudinal direction of the bridge and are connected in series through the cast-in-place longitudinal reinforcement 9.5 located in the cast-in-place concrete layer 7.

[0036] Furthermore, the old bridge steel frame unit includes guardrail embedded steel bars 9.1 and cast-in-place layer transverse steel bars 9.4; the guardrail embedded steel bars 9.1 are U-shaped structures and are set in the top plate 1 of the old bridge box girder. One end of the guardrail embedded steel bars 9.1 is located below the elastic body 4 and flush with the upper surface of the top plate 1 of the old bridge box girder, and the other end extends into the cast-in-place concrete layer 7; the cast-in-place layer transverse steel bars 9.4 are set in the cast-in-place concrete layer 7, one end of which is connected to the end of the guardrail embedded steel bars 9.1 located in the cast-in-place concrete layer 7, and the other end of which is connected to the steel frame 3, specifically to the side of the flange plate away from the web plate; the cast-in-place layer longitudinal steel bars 9.5 are connected to the cast-in-place layer transverse steel bars 9.4.

[0037] Furthermore, the old bridge steel frame unit also includes vertical reinforcement bars 9.2. The lower part of the vertical reinforcement bars 9.2 is set in the top plate 1 of the old bridge box girder and the lower end is connected to the guardrail embedded reinforcement bars 9.1. The upper part is set in the cast-in-place concrete layer 7 and connected to the transverse reinforcement bars 9.4 of the cast-in-place layer. The upper part of the vertical reinforcement bars 9.2 is also connected to the side of the flange plate away from the web plate in the steel frame 3 through the anchor plate 6.

[0038] Furthermore, the old bridge steel frame unit also includes longitudinal steel bars 9.3 of the old bridge top slab. Multiple longitudinal steel bars 9.3 of the old bridge top slab are arranged at intervals along the transverse direction of the bridge. Some of the longitudinal steel bars 9.3 of the old bridge top slab can be connected with the guardrail embedded steel bars 9.1 and the vertical anchor bars 9.2. Of course, it can also be set so that the longitudinal steel bars 9.3 of the old bridge top slab are not connected with the guardrail embedded steel bars 9.1 and the vertical anchor bars 9.2. This depends on the arrangement of the longitudinal steel bars 9.3 of the old bridge top slab, the guardrail embedded steel bars 9.1, and the vertical anchor bars 9.2.

[0039] like Figure 2 As shown, a portion of the steel reinforcement cage 10 of the new bridge is located in the top slab 2 of the new bridge box girder, and another portion is located in the cast-in-place concrete layer 7 on the top slab 2 of the new bridge box girder, and this portion is connected to the steel cage 3 on the top slab 2 of the new bridge box girder.

[0040] Specifically, the new bridge steel reinforcement frame 10 includes new bridge steel frame units and new bridge top plate longitudinal reinforcement 10.4. The new bridge steel frame units are located in the new bridge box girder top plate 2, with a portion located in the cast-in-place concrete layer 7 and connected to the steel frame 3 through this portion. Multiple new bridge steel frame units are spaced apart along the longitudinal direction of the bridge and are connected in series by the new bridge top plate longitudinal reinforcement 10.4 located in the new bridge box girder top plate 2. The number of new bridge top plate longitudinal reinforcement 10.4 is multiple and they are spaced apart along the transverse direction of the bridge.

[0041] Furthermore, the new bridge steel frame unit includes box girder facade stirrups 10.1, embedded vertical reinforcement bars 10.2, and new bridge top slab transverse reinforcement bars 10.3. The box girder facade stirrups 10.1 and the new bridge top slab transverse reinforcement bars 10.3 are both located in the new bridge box girder top slab 2. The box girder facade stirrups 10.1 are located below the new bridge top slab transverse reinforcement bars 10.3, and the end of the box girder facade stirrups 10.1 near the splice joint 11 is bent and connected to the end of the new bridge top slab transverse reinforcement bars 10.3. The new bridge top slab transverse reinforcement bars 10.3 are connected to the new bridge top slab longitudinal reinforcement bars 10.4. The lower part of the embedded vertical reinforcement bars 10.2 is located in the new bridge box girder top slab 2 and is connected to the box girder facade stirrups 10.1 and the new bridge top slab transverse reinforcement bars 10.3 in sequence. The upper part is located in the cast-in-place concrete layer 7 and is connected to the side of the flange plate away from the web plate in the steel frame 3 through the anchor plate 6. Furthermore, the lower end of the pre-embedded vertical steel bar 10.2 is bent and connected to the stirrup 10.1 on the facade of the box girder.

[0042] It should be noted that the above description only illustrates one arrangement of the new bridge steel reinforcement cage 10 and the old bridge steel reinforcement cage 9. In some embodiments, the new bridge steel reinforcement cage 10 and the old bridge steel reinforcement cage 9 may adopt other arrangements. Those skilled in the art can flexibly adjust the structural form of the new bridge steel reinforcement cage 10 and the old bridge steel reinforcement cage 9 according to the actual site conditions and design requirements. In this embodiment, the preferred connection method between steel bars is welding or lap splicing, and the preferred connection method between steel bars and steel plates (such as flange plates, web plates, and anchor plates) is welding.

[0043] Preferably, the upper surface of the steel frame shall not exceed the design height of the road surface, and the upper surfaces of the asphalt surface layer 8, the elastomer 4 and the cast-in-place concrete layer 7 shall be flush to ensure the smoothness of the road surface; the cast-in-place concrete layer 7 shall be C50 steel fiber concrete poured on site.

[0044] The construction process for the longitudinal expansion joint structure in this embodiment is as follows:

[0045] Determine the width of the joint between the old and new bridges, determine the location of the new bridge's pile foundations based on the joint width, and complete the construction of the new bridge's substructure.

[0046] Remove the crash barrier on the side of the old bridge closest to the new bridge, insert vertical reinforcing bars 9.2 on the side of the old bridge box girder top slab 1 near the splice joint, and cast the box girder body of the new bridge in place; when casting the box girder body of the new bridge, the box girder vertical stirrups 10.1, the pre-embedded vertical reinforcing bars 10.2, the transverse reinforcing bars 10.3 and the longitudinal reinforcing bars 10.4 of the new bridge top slab must be installed in the beam body as required;

[0047] The old bridge will be grouted, which means removing the asphalt surface layer 8 within the range of the elastomer and cast-in-place concrete layer. The grooving width and depth should be controlled to meet the design requirements.

[0048] Install the transverse reinforcement 9.4 and longitudinal reinforcement 9.5 of the cast-in-place layer, as well as the steel frame 3 and anchor plate 6 on the new and old bridges. Then pour the cast-in-place concrete layer 7, and finally pour the elastic body and cure it as required.

[0049] During construction, attention should be paid to the cleanliness of the bonding interface when applying materials in the trench, and there should be no standing water during the process. The mixing ratio of each material must be strictly implemented according to regulations. The pouring and curing of materials in the trench should be carried out at a temperature of 5-35℃. Construction in the trench should not be carried out when the temperature exceeds this range or on rainy days, unless there are insulation and rainproof measures.

[0050] In this embodiment, the longitudinal expansion joint structure only requires cutting away a portion of the asphalt surface layer near the joint of the old bridge to complete the construction of the longitudinal expansion joint, reducing the damage to the old bridge and improving the construction efficiency of the longitudinal expansion joint structure. At the same time, the steel frames on both sides are connected to the steel reinforcement frame 10 of the new bridge and the steel reinforcement frame 9 of the old bridge, respectively. After the construction of the elastic body and the cast-in-place concrete layer, the new and old bridge bodies form an integral structure. Both the elastic body and the asphalt surface layer are flexible, which greatly improves the driving comfort.

[0051] In the longitudinal expansion joint structure of this embodiment, corrugated plates are connected between the steel frames on both sides, which can deform together with the elastomer, effectively buffering and absorbing the vibrations generated by vehicle driving and improving the comfort of vehicle driving.

[0052] Example 2:

[0053] like Figure 3 As shown, the longitudinal expansion joint structure for widening the old bridge in this embodiment differs from that in embodiment 1 in that the corrugated plate 5 is disposed inside the elastic body 4, and the two ends of the corrugated plate 5 are respectively connected to the web plates on the two steel frames 3.

[0054] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A longitudinal expansion joint structure suitable for widening old bridges, wherein the top plate (1) of the old bridge box girder and the top plate (2) of the new bridge box girder are flush and a widening joint (11) is provided between them, characterized in that: The old bridge box girder top plate (1) is provided with a steel frame (3) on the side near the splice joint (11), and the steel frame (3) is connected to the old bridge steel reinforcement frame (9) in the old bridge box girder top plate (1). The new bridge box girder top plate (2) is provided with a steel frame (3) on the side near the splice joint (11), and the steel frame (3) is connected to the new bridge steel reinforcement frame (10) in the new bridge box girder top plate (2). An elastic body (4) and a corrugated plate (5) are provided between the two steel frames (3). A cast-in-place concrete layer (7) is provided between the steel frame on the top plate (1) of the old bridge box girder and the asphalt surface layer (8) on the top plate (1) of the old bridge box girder, and between the steel frame on the top plate (2) of the new bridge box girder and the asphalt surface layer (8) on the top plate (2) of the new bridge box girder.

2. The longitudinal expansion joint structure for widening old bridges according to claim 1, characterized in that, The steel frame (3) includes a flange plate and a web plate. The web plate is disposed on the flange plate and the two form a T-shaped structure. The side of the flange plate with the web plate is fitted with the elastomer (4). The web plate extends into the interior of the elastomer (4).

3. The longitudinal expansion joint structure for widening old bridges according to claim 1, characterized in that, Two steel frames (3) are connected to both sides of the corrugated plate (5), and the corrugated plate (5) is disposed inside the elastic body (4) or at the bottom of the elastic body (4).

4. The longitudinal expansion joint structure for widening old bridges according to claim 1, characterized in that, A portion of the old bridge steel reinforcement skeleton (9) is located in the top plate (1) of the old bridge box girder, and another portion is located in the cast-in-place concrete layer (7) on the top plate (1) of the old bridge box girder, and this portion is connected to the steel skeleton (3) on the top plate (1) of the old bridge box girder; A portion of the steel reinforcement skeleton (10) of the new bridge is located in the top plate (2) of the new bridge box girder, and another portion is located in the cast-in-place concrete layer (7) on the top plate (2) of the new bridge box girder, and this portion is connected to the steel skeleton (3) on the top plate (2) of the new bridge box girder.

5. The longitudinal expansion joint structure for widening old bridges according to claim 4, characterized in that, The old bridge steel reinforcement frame (9) includes old bridge steel frame units and cast-in-place longitudinal reinforcement (9.5). One part of the old bridge steel frame unit is located in the top plate (1) of the old bridge box girder, and the other part is located in the cast-in-place concrete layer (7) and is connected to the steel frame (3) through this part. Multiple old bridge steel frame units are arranged at intervals along the longitudinal direction of the bridge and are connected in series by cast-in-place longitudinal reinforcement (9.5) in the cast-in-place concrete layer (7).

6. The longitudinal expansion joint structure for widening old bridges according to claim 5, characterized in that, The old bridge steel frame unit includes guardrail embedded steel bars (9.1) and cast-in-place layer transverse steel bars (9.4); the guardrail embedded steel bars (9.1) are U-shaped structures and are set in the top plate (1) of the old bridge box girder. One end of the guardrail embedded steel bars (9.1) is located below the elastic body (4) and is flush with the upper surface of the top plate (1) of the old bridge box girder, and the other end extends into the cast-in-place concrete layer (7); the cast-in-place layer transverse steel bars (9.4) are set in the cast-in-place concrete layer (7), one end of which is connected to the end of the guardrail embedded steel bars (9.1) located in the cast-in-place concrete layer (7), and the other end of which is connected to the steel frame (3). The cast-in-place layer longitudinal steel bars (9.5) are connected to the cast-in-place layer transverse steel bars (9.4).

7. The longitudinal expansion joint structure for widening old bridges according to claim 6, characterized in that, The old bridge steel frame unit also includes vertical rebar (9.2). The lower part of the vertical rebar (9.2) is set in the top plate (1) of the old bridge box girder and its lower end is connected to the guardrail embedded rebar (9.1). Its upper part is set in the cast-in-place concrete layer (7) and is connected to the cast-in-place layer transverse rebar (9.4). The upper part of the vertical rebar (9.2) is also connected to the steel frame (3) through the anchor plate (6).

8. The longitudinal expansion joint structure for widening old bridges according to claim 4, characterized in that, The new bridge steel reinforcement frame (10) includes new bridge steel frame units and new bridge top plate longitudinal reinforcement (10.4). The new bridge steel frame units are located in the new bridge box girder top plate (2), and a portion of them are located in the cast-in-place concrete layer (7) and connected to the steel frame (3) through this portion. Multiple new bridge steel frame units are arranged at intervals along the longitudinal direction of the bridge and are connected in series with each new bridge steel frame unit through the new bridge top plate longitudinal reinforcement (10.4) located in the new bridge box girder top plate (2).

9. The longitudinal expansion joint structure for widening old bridges according to claim 8, characterized in that, The new bridge steel frame unit includes box girder facade stirrups (10.1), embedded vertical reinforcement bars (10.2), and new bridge top slab transverse reinforcement bars (10.3); the box girder facade stirrups (10.1) and the new bridge top slab transverse reinforcement bars (10.3) are both located in the new bridge box girder top slab (2), the box girder facade stirrups (10.1) are located below the new bridge top slab transverse reinforcement bars (10.3), and the box girder facade stirrups (10.1) are close to the joint (11). After the end is bent, it is connected to the end of the transverse reinforcement (10.3) of the new bridge top plate. The transverse reinforcement (10.3) of the new bridge top plate is connected to the longitudinal reinforcement (10.4) of the new bridge top plate. The lower part of the pre-embedded vertical reinforcement (10.2) is located in the top plate (2) of the new bridge box girder and is connected to the box girder vertical stirrup (10.1) and the transverse reinforcement (10.3) of the new bridge top plate in sequence. Its upper part is located in the cast-in-place concrete layer (7) and is connected to the steel frame (3) through the anchor plate (6).

10. The longitudinal expansion joint structure for widening old bridges according to claim 9, characterized in that, The lower end of the pre-embedded vertical steel bar (10.2) is bent and connected to the stirrup (10.1) on the facade of the box girder.

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