Bridge expansion joint beam interior preset unit and installation method thereof

Abstract

The application belongs to the technical field of bridge engineering, and particularly relates to a bridge expansion joint beam body internal preset unit and a mounting method thereof. The unit is arranged at the end of a bridge main body to which an expansion joint is mounted. The bridge main body is internally provided with main steel bars. The upper surface of the bridge main body is sequentially provided with a waterproof concrete layer and an asphalt layer from bottom to top. A first box body is pre-buried in the bridge main body, and the top end of the first box body is flush with the top end of the bridge main body. The upper surface of the first box body is provided with a positioning rod extending upward. The first box body is pre-buried in the bridge main body, and a steel bar cage and connecting bolts are arranged in the first box body. The factory prefabrication of an expansion joint anchoring interface is realized. The welding quality of the steel bar cage and the connecting steel bars can be detected in the factory, so that the problem of uneven welding quality on site is avoided, and the installation precision and reliability are improved.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering, specifically relating to a pre-installed unit inside the beam of a bridge expansion joint and its installation method. Background Technology

[0002] Bridge expansion joints are an important component of bridge structures, used to accommodate expansion and contraction caused by factors such as temperature changes, concrete shrinkage and creep, and vehicle loads. Currently, the installation of bridge expansion joints mainly relies on the pre-embedded steel bar method. This involves pre-embedding loose steel bars as anchor bars during the pouring of the bridge main structure. After the main structure is completed, the concrete at the expansion joint location is removed to expose the pre-embedded steel bars, and then the expansion joint is welded and fixed to the steel bars on site.

[0003] However, the embedded reinforcing bars are prone to displacement and tilting during concrete pouring and vibration, leading to misalignment of the holes when installing the expansion joints later. Furthermore, the bond between the embedded reinforcing bars and concrete relies solely on smooth surface friction, resulting in insufficient grip and easy loosening and pull-out under repeated loads. Simultaneously, the welding quality between the anchor bars and the embedded reinforcing bars depends heavily on the skill of on-site workers, resulting in inconsistent quality. Different models of expansion joints require different embedded parts, leading to poor versatility and complex inventory management. In addition, after the main bridge construction is completed, the installation location of the expansion joints is covered by a waterproof concrete layer and asphalt layer. Later, finding the excavation location requires experience, which can easily damage the main bridge structure. Moreover, the embedded reinforcing bars are exposed to the construction site environment, making them susceptible to contamination from concrete slurry and oil. After removing the concrete, manual cleaning, rust removal, and straightening are required, a tedious process that leaves hard-to-reach areas difficult to clean thoroughly.

[0004] Therefore, it is necessary to design a pre-installed unit that is accurately positioned, reliably anchored, and easy to identify for the rapid installation of bridge expansion joints. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a prefabricated unit inside the beam of a bridge expansion joint and its installation method, which enables factory prefabrication of the anchorage interface of the expansion joint, avoids the problem of uncontrollable on-site welding quality, protects the connection interface from construction pollution, and facilitates rapid identification of the installation position in the later stage, thereby improving installation efficiency.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] A pre-installed unit inside the beam of a bridge expansion joint is provided at the end of the bridge body where the expansion joint is installed. The bridge body is provided with main steel bars inside, and the upper surface of the bridge body is provided with a waterproof concrete layer and an asphalt layer from bottom to top. The feature is that a first box is pre-embedded inside the bridge body, and the top of the first box is flush with the top of the bridge body. The upper surface of the first box is provided with an upwardly extending positioning rod.

[0008] A detachable second box is provided above the first box. The second box is embedded inside the waterproof concrete layer, and the top of the second box is flush with the top of the waterproof concrete layer. The second box is positioned and connected to the first box by means of a positioning rod.

[0009] The asphalt layer is located on the waterproof concrete layer and the second box, and covers the waterproof concrete layer and the second box.

[0010] Furthermore, a display block is provided on the upper surface of the second housing, and the top surface of the display block is flush with the top surface of the asphalt layer.

[0011] Furthermore, a steel cage is fixedly connected inside the first box, and connecting bolts are provided on the steel cage. A detachable sealing plate is provided at the top of the first box.

[0012] Furthermore, the second housing is provided with a top plate, on which multiple through holes are formed.

[0013] Furthermore, the second housing is equipped with a displacement device inside. The displacement device is connected to the top plate by means of positioning bolts and positioning nuts, and the displacement device has a connection hole that matches the connecting bolts.

[0014] Furthermore, the second housing has positioning holes that are compatible with the positioning rod.

[0015] Furthermore, the displacement device is equipped with a fixing bolt, and the fixing bolt abuts against the lower surface of the top plate. The displacement device is connected to the bridge expansion joint by means of the fixing bolt and the fixing nut.

[0016] Furthermore, the steel cage inside the first box is fixedly connected to the connecting steel bars inside the main body of the bridge.

[0017] Furthermore, this includes the following steps:

[0018] S1. When constructing the main body of the bridge, the first box is pre-embedded in the main body of the bridge, so that the steel cage is connected with the connecting steel bars, and the concrete of the main body of the bridge is poured, so that the top of the first box is flush with the upper surface of the main body of the bridge.

[0019] S2. Remove the top plate above the first box to expose the steel cage and connecting bolts. Install the second box above the first box. A displacement device is hoisted under the top plate of the second box. Insert the positioning rod into the reserved position of the first box and make the positioning rod pass into the positioning hole on the side of the second box. Connect and fix the second box to the first box. At the same time, the connecting bolt passes through the connecting hole.

[0020] S3. Insert washers onto the connecting bolts to cover the gap between the connecting bolts and the connecting holes. Tighten the nuts that fit the connecting bolts onto the connecting bolts to connect and fix the steel cage to the displacement device. Fill the interior of the first and second boxes with sand or small stones through the through holes on the top plate as support. Then cover the top plate with the sealing plate of the second box to seal the through holes.

[0021] S4. Lay a waterproof concrete layer on the main body of the bridge and the upper part of the second box girder, so that the waterproof concrete layer is flush with the top surface of the top plate of the second box girder, and level the waterproof concrete layer.

[0022] S5. After the concrete has solidified, lay an asphalt layer to cover the waterproof concrete layer and the second box. Place a display block as a pad on the sealing plate of the second box. The top surface of the display block is flush with the top surface of the asphalt layer and exposed on the surface of the asphalt layer.

[0023] S6. When installing the bridge expansion joint in the later stage, according to the position of the display block, remove the waterproof concrete layer and asphalt layer of that part, open the sealing plate, and clean the sand or small stones inside the two boxes through the through hole to expose the steel cage and displacement device. After adjusting the angle of the displacement device, remove the side plates of the first box and the second box near the beam end and the side plates at both ends on the left and right.

[0024] S7. Finally, angle irons are placed at the beam ends and welded to the steel cage and connecting steel bars. The water guide plate of the expansion joint is installed on the angle irons. The angle irons are closed at the beam ends to form a pouring pit. Then, concrete is poured into the pouring pit so that the concrete is flush with the lower end of the fixing bolt. After the concrete has solidified, the bridge expansion joint is connected and fixed to the displacement device with the fixing bolts and fixing nuts.

[0025] Furthermore, in step S2, the top plate of the second housing is equipped with a displacement device by means of positioning bolts. Multiple sets of positioning bolts are arranged at intervals along the length of the displacement device. Fixing bolts are also provided on both sides of the positioning bolts. The fixing bolts are threadedly and adjustablely connected to the displacement device. The overhanging end of the fixing bolt abuts against the top plate of the second housing to adjust the angle of the displacement device relative to the top plate.

[0026] The beneficial effects of this invention are:

[0027] The invention employs a method of pre-embedding a first box within the main body of the bridge, and installing a steel cage and connecting bolts inside the first box. This enables the factory prefabrication of the anchorage interface of the expansion joint. The welding quality of the steel cage and connecting steel bars can be tested in the factory, avoiding the problem of inconsistent welding quality on site and improving installation accuracy and reliability.

[0028] With the help of the positioning rod and positioning hole, the second box can be quickly and accurately installed on top of the first box. The second box protects the steel cage and connecting bolts, avoiding contamination and damage to the connection interface by concrete, asphalt and other debris during subsequent construction. After the second box is removed, a clean and complete connection interface can be exposed without the need for tedious operations such as cleaning and straightening, which greatly improves construction efficiency.

[0029] The top surface of the display block is flush with the top surface of the asphalt layer, serving as a location marker when installing bridge expansion joints later. This allows construction workers to accurately identify the excavation location based on the position of the display block, avoiding damage to the main structure of the bridge from blind excavation and achieving rapid and accurate positioning of the expansion joint installation location.

[0030] The sand or small stones filling the first and second box bodies serve as support and filler, preventing the box bodies from deforming due to concrete pressure or vehicle loads during construction. At the same time, the sand or small stones facilitate cleaning during later dismantling, improving construction convenience and achieving a rapid and integrated connection between the expansion joint and the main bridge structure. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the construction completion status of step S1 provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the construction completion status of step S6 provided in an embodiment of the present invention;

[0033] Figure 3 This is a top view of the first box structure provided in an embodiment of the present invention;

[0034] Figure 4 This is a top view of the second housing structure provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the construction completion status of step S7 provided in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the construction completion status of step S8 provided in an embodiment of the present invention.

[0037] In the attached diagram, 1. Bridge main body; 11. Main reinforcing bars; 12. Connecting reinforcing bars; 2. Waterproof concrete layer; 3. Asphalt layer; 4. First box girder; 41. Positioning rod; 42. Reinforcing cage; 43. Connecting bolt; 5. Second box girder; 51. Display block; 52. Positioning bolt; 53. Displacement device; 54. Connecting hole; 55. Fixing bolt; 56. Positioning hole; 6. Fixing nut; 7. Bridge expansion joint. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0039] The present invention is as follows Figure 1 As shown, a pre-installed unit inside the beam of a bridge expansion joint and its installation method are disclosed. The unit is installed at the end of the bridge body 1 where the expansion joint is installed. The bridge body 1 has a main steel bar 11 inside. The upper surface of the bridge body 1 is provided with a waterproof concrete layer 2 and an asphalt layer 3 from bottom to top.

[0040] The bridge body 1 has a first box 4 embedded inside, and the top of the first box 4 is flush with the top of the bridge body 1. The upper surface of the first box 4 is provided with an upwardly extending positioning rod 41.

[0041] like Figure 1 and Figure 2 As shown, a steel cage 42 is fixedly connected inside the first box 4, and a connecting bolt 43 is provided on the steel cage 42. A detachable sealing plate is provided on the top of the first box 4. The steel cage 42 inside the first box 4 is fixedly connected to the connecting steel bar 12 inside the bridge body 1.

[0042] This invention achieves factory prefabrication of the anchorage interface of the expansion joint by pre-embedding a first box 4 inside the main body 1 of the bridge and setting a steel cage 42 and connecting bolts 43 inside the first box 4, thus avoiding the problem of uncontrollable on-site welding quality and improving installation accuracy and reliability.

[0043] A detachable second box 5 is provided above the first box 4. The second box 5 is embedded inside the waterproof concrete layer 2, and the top of the second box 5 is flush with the top of the waterproof concrete layer 2. The second box 5 is positioned and connected to the first box 4 by means of a positioning rod 41.

[0044] like Figure 4 As shown, the second housing 5 has a positioning hole 56 that matches the positioning rod 41. The positioning rod 41 is inserted upward into the positioning hole 56 to achieve a precise positioning connection between the first housing 4 and the second housing 5.

[0045] The present invention enables the second housing 5 to be quickly and accurately installed on top of the first housing 4 by the cooperation of the positioning rod 41 and the positioning hole 56, avoiding the tedious operation of on-site positioning adjustment and improving construction efficiency.

[0046] The upper surface of the second housing 5 is provided with a display block 51, and the top surface of the display block 51 is flush with the top surface of the asphalt layer 3.

[0047] like Figure 2 As shown, the asphalt layer 3 is located on the waterproof concrete layer 2 and the second box 5, and covers the waterproof concrete layer 2 and the second box 5.

[0048] Display block 51 serves as a position marker during the later installation of bridge expansion joint 7, facilitating construction personnel to accurately identify the excavation location based on the position of display block 51, thus avoiding damage to the main structure of the bridge 1 caused by blind excavation.

[0049] like Figure 4 As shown, the top of the second housing 5 is provided with a top plate 52, and multiple through holes are provided on the top plate 52. The interior of the second housing 5 is provided with a displacement device 53. The displacement device 53 is connected to the top plate 52 by means of positioning bolts 521 and positioning nuts 522. The displacement device 53 is provided with connecting holes 54 that are compatible with connecting bolts 43. The displacement device 53 is provided with fixing bolts 55, and the fixing bolts 55 abut against the lower surface of the top plate 52. The displacement device 53 is connected to the bridge expansion device 7 by means of fixing bolts 55 and fixing nuts 6.

[0050] The present invention achieves the positioning of the displacement device 53 by adjusting the inclination of the displacement device 55 according to the slope of the top of the bridge body 1 and the corresponding rotating fixing bolt 55, while ensuring the flatness when installing the bridge expansion device 7 later.

[0051] A method for installing pre-installed units inside the beam of a bridge expansion joint includes the following steps:

[0052] S1. When the main body of the bridge is constructed, the first box 4 is pre-embedded in the main body of the bridge, so that the steel cage 42 is connected with the connecting steel bar 12, and the concrete of the main body of the bridge is poured, so that the top of the first box 4 is flush with the upper surface of the main body of the bridge.

[0053] like Figure 1 and Figure 2 As shown, after the first box 4 is pre-embedded, it is filled with spacer foam blocks to prevent concrete from entering the first box 4 during the pouring of the bridge main body. After the pouring is completed and the concrete has initially set, the foam blocks are removed, with their tops flush with the top of the bridge main body 1. The reinforcing cage 42 and connecting bolts 43 are located inside the first box 4, awaiting subsequent construction. This step realizes the factory prefabrication of the expansion joint anchorage foundation. The welding quality of the reinforcing cage 42 and the connecting reinforcing bars 12 can be tested in the factory, avoiding the problem of inconsistent welding quality on site.

[0054] S2. Remove the top plate above the first box 4 to expose the steel cage 42 and connecting bolts 43. Install the second box 5 above the first box 4. A displacement device 53 is hoisted under the top plate 52 of the second box 5. Insert the positioning rod 41 into the reserved position of the first box 4 and make the positioning rod 41 pass into the positioning hole 56 on the side of the second box 5 to connect and fix the second box 5 to the first box 4. At the same time, the connecting bolts 43 pass through the connecting hole 54.

[0055] S3. Insert a washer onto the connecting bolt 43 to cover the gap between the connecting bolt 43 and the connecting hole 54. Tighten the nut that fits the connecting bolt 43 onto the connecting bolt 43 to connect and fix the reinforcing cage 42 to the displacement device 53. Fill the interior of the first box 4 and the second box 5 with sand or small stones through the through hole on the top plate 52 as support. Then cover the top plate 52 with the sealing plate of the second box 5 to seal the through hole.

[0056] like Figure 2 and Figure 4 As shown, after the second housing 5 is installed, the positioning rod 41 passes through the positioning hole 56 to achieve precise positioning of the first housing 4 and the second housing 5. At this time, the connecting steel bar 12, connecting bolt 43, strip seat-shaped displacement device 53 and fixing bolt 55 set on the displacement device 53 form effective support for the top plate 52 of the second housing 5, which can prevent the top plate 52 from deforming when the asphalt layer is compacted later, and provide a good foundation for adjusting the angle of the displacement device 53 later. This step protects the steel cage 42 and connecting bolt 43 by using the detachable second housing 5, avoiding contamination and damage to the connection interface by concrete, asphalt and other debris during subsequent construction.

[0057] S4. Lay a waterproof concrete layer 2 on the upper part of the main body 1 and the second box 5 of the bridge, so that the waterproof concrete layer 2 is flush with the top surface of the top plate 52 of the second box 5, and level the waterproof concrete layer 2.

[0058] like Figure 2 As shown, after the waterproof concrete layer 2 is laid, its top surface is flush with the top of the second box 5, and the second box 5 is embedded inside the waterproof concrete layer 2. This step covers and protects the second box 5 with the waterproof concrete layer 2, allowing construction workers to continue normal construction.

[0059] S5. After the concrete has solidified, lay the asphalt layer 3 so that the asphalt layer 3 covers the waterproof concrete layer 2 and the second box 5. Place the display block 51 as a pad on the sealing plate of the second box 5. The top surface of the display block 51 is flush with the top surface of the asphalt layer 3 and exposed on the surface of the asphalt layer 3.

[0060] like Figure 2 As shown, after the asphalt layer 3 is laid, the top surface of the display block 51 is flush with the top surface of the asphalt layer 3. The display block 51 serves as a marker for later construction, facilitating accurate positioning. This step, by aligning the display block 51 with the asphalt layer 3, enables rapid identification of the installation location of the expansion joint, avoiding blind spots during later excavation.

[0061] S6. When installing the bridge expansion joint 7 later, according to the position of the display block 51, remove the waterproof concrete layer 2 and asphalt layer 3 at that location, open the sealing plate, and clean the sand or small stones inside the two boxes through the through hole to expose the steel cage 42 and the displacement device 53. After adjusting the angle of the displacement device 53, remove the side plates of the first box 4 and the second box 5 near the beam end and the side plates at both ends on the left and right sides.

[0062] When adjusting the angle of the displacement device 53, remove the nut of the connecting bolt 43, add a shim between the top plate 52 and the second housing 5, and adjust the top surface of the top plate 52 to be flush with the surface of the asphalt layer by using the shim. At this time, adjust the displacement device 53 to the design depth relative to the surface of the asphalt layer by tightening the positioning bolt 521 through the through hole. Then adjust the extension length of the fixing bolts 55 on both sides so that the displacement device 53 swings under the suspension of the positioning bolt 521, ensuring that the connection surface between the displacement device 53 and the bridge expansion device 7 is within the design angle range. Tighten the nut of the connecting bolt 43 to complete the fixation of the displacement device 53. Then remove the positioning bolt 521, remove the top plate 52, and proceed with subsequent operations.

[0063] like Figure 5 As shown, after the side walls of the second housing 5 and the first housing 4 are removed, the reinforcing cage 42, connecting bolts 43, and displacement device 53 are exposed. This step, by removing the double-housing structure, exposes a clean and complete connection interface, avoiding the tedious operations of cleaning and straightening reinforcing bars in traditional processes, and greatly improving installation efficiency.

[0064] S7. Finally, angle irons are placed at the beam ends and welded to the steel cage 42 and connecting steel bars 12. The water guide plate of the expansion joint is installed on the angle irons. The angle irons are closed close to the beam ends to form a pouring pit. Then, concrete is poured into the pouring pit so that the concrete is flush with the lower end of the fixing bolt 55. After the concrete has solidified, the bridge expansion joint 7 is connected and fixed to the displacement device 53 with the fixing bolt 55 and fixing nut 6.

[0065] like Figure 5 As shown, after the bridge expansion joint 7 is installed, it is fastened to the displacement device 53 by fixing bolts 55 and fixing nuts 6 to achieve reliable anchoring between the expansion joint and the pre-set unit. Finally, the expansion joint and the bridge main body are integrated by concrete pouring and bolt tightening.

Claims

1. A bridge expansion device beam interior preset unit, provided at the end of the bridge main body (1) where the expansion device is installed, the interior of the bridge main body (1) is provided with a main reinforcement (11), and the upper surface of the bridge main body (1) is sequentially provided with a waterproof concrete layer (2) and an asphalt layer (3) from bottom to top, characterized in that, The bridge body (1) has a first box (4) embedded inside, and the top of the first box (4) is flush with the top of the bridge body (1). The upper surface of the first box (4) is provided with an upwardly extending positioning rod (41). A detachable second box (5) is provided above the first box (4). The second box (5) is embedded in the interior of the waterproof concrete layer (2), and the top of the second box (5) is flush with the top of the waterproof concrete layer (2). The second box (5) is positioned and connected to the first box (4) by means of a positioning rod (41). The asphalt layer (3) is located on the waterproof concrete layer (2) and the second box (5) and covers the waterproof concrete layer (2) and the second box (5).

2. The pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The upper surface of the second box (5) is provided with a display block (51), and the top surface of the display block (51) is flush with the top surface of the asphalt layer (3).

3. The pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The first box (4) is fixedly connected to a steel cage (42), the steel cage (42) is provided with connecting bolts (43), and the top of the first box (4) is provided with a detachable sealing plate.

4. The pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The top of the second box (5) is provided with a top plate (52), and the top plate (52) has multiple through holes.

5. A pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The second housing (5) is provided with a displacement device (53). The displacement device (53) is connected to the top plate (52) by means of positioning bolts (521) and positioning nuts (522). The displacement device (53) is provided with a connection hole (54) that is compatible with the connecting bolts (43).

6. A pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The second housing (5) has a positioning hole (56) that is compatible with the positioning rod (41).

7. A pre-installed unit inside the beam of a bridge expansion joint according to claim 5, characterized in that, The displacement device (53) is provided with a fixing bolt (55), and the fixing bolt (55) abuts against the lower surface of the top plate (52). The displacement device (53) is connected to the bridge expansion device (7) by means of the fixing bolt (55) and the fixing nut (6).

8. A pre-installed unit inside the beam of a bridge expansion joint according to claim 1, characterized in that, The steel cage (42) inside the first box (4) is fixedly connected to the connecting steel bar (12) inside the main body of the bridge (1).

9. A method for installing a pre-installed unit inside the beam of a bridge expansion joint, based on the pre-installed unit inside the beam of a bridge expansion joint according to any one of claims 1-8, characterized in that, Includes the following steps: S1. When the main body of the bridge (1) is being constructed, the first box (4) is pre-embedded in the main body of the bridge (1), so that the steel cage (42) is connected to the connecting steel bar (12), and the concrete of the main body of the bridge (1) is poured, so that the top of the first box (4) is flush with the upper surface of the main body of the bridge (1). S2. Remove the top plate above the first box (4) to expose the steel cage (42) and connecting bolts (43). Install the second box (5) above the first box (4). A displacement device (53) is hoisted under the top plate (52) of the second box (5). Insert the positioning rod (41) into the reserved position of the first box (4) and make the positioning rod (41) pass into the positioning hole (56) on the side of the second box (5). Connect and fix the second box (5) to the first box (4). At the same time, the connecting bolts (43) pass through the connecting hole (54). S3. Insert washers onto the connecting bolts (43) to cover the gap between the connecting bolts (43) and the connecting hole (54). Tighten the nuts that fit the connecting bolts (43) onto the connecting bolts (43) to connect and fix the steel cage (42) and the displacement device (53). Fill the first box (4) and the second box (5) with sand or small stones through the through hole on the top plate (52) as support. Then cover the top plate (52) with the sealing plate of the second box (5) to seal the through hole. S4. Lay a waterproof concrete layer (2) on the upper part of the main body (1) and the second box (5) of the bridge so that the waterproof concrete layer (2) is flush with the top surface of the top plate (52) of the second box (5) and level the waterproof concrete layer (2). S5. After the concrete has solidified, lay an asphalt layer (3) so that the asphalt layer (3) covers the waterproof concrete layer (2) and the second box (5). Place a display block (51) as a pad on the sealing plate of the second box (5). The top surface of the display block (51) is flush with the top surface of the asphalt layer (3) and exposed on the surface of the asphalt layer (3). S6. When installing the bridge expansion joint (7) later, according to the position of the display block (51), remove the waterproof concrete layer (2) and asphalt layer (3) of that part, open the sealing plate, and clean the sand or small stones inside the two boxes through the through hole to expose the steel cage (42) and displacement device (53). After adjusting the angle of the displacement device (53), remove the side plates of the first box (4) and the second box (5) near the beam end and the side plates at both ends of the left and right sides. S7. Finally, angle irons are arranged at the beam ends. The angle irons are welded and fixed to the steel cage (42) and the connecting steel bars (12). The water guide plate of the expansion device is installed on the angle irons. The angle irons are closed close to the beam ends to form a pouring pit. Then, concrete is poured at the position of the pouring pit so that the concrete is flush with the lower end of the fixing bolt (55). After the concrete solidifies, the bridge expansion device (7) is connected and fixed to the displacement device (53) with the fixing bolt (55) and fixing nut (6).

10. The method for installing a pre-installed unit inside the beam of a bridge expansion joint according to claim 9, characterized in that: In step S2, the top plate (52) of the second housing (5) is equipped with a displacement device (53) by means of positioning bolts (521). Multiple sets of positioning bolts (521) are arranged at intervals along the length of the displacement device (53). Fixing bolts (55) are also provided on both sides of the positioning bolts (521). The fixing bolts (55) are threadedly and adjustablely connected to the displacement device (53). The overhanging end of the fixing bolts (55) abuts against the top plate (52) of the second housing (5) to adjust the angle of the displacement device (53) relative to the top plate (52).

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