A long-span integral reinforcing device and method for the lower flange of a composite steel beam

Abstract

The application belongs to the technical field of building engineering, and proposes a long-span integral reinforcing device and method for the lower flange of a combined steel beam. Steel beam hoop plates are arranged on two adjacent steel columns. Each steel beam hoop plate is connected with a flange upper cover plate. At least two flange upper cover plates are independently arranged on the lower flange. A lower cover plate is arranged on each flange upper cover plate to realize non-destructive clamping of the flange. Connecting rods are arranged between the adjacent two flange upper cover plates at the end of the lower flange. Steel strands are arranged between all the flange upper cover plates independently arranged on the lower flange. All the flange upper cover plates are connected through the connecting rods and the steel strands. A continuous constraint system is formed between the multiple reinforcing areas. The device is suitable for the integral reinforcement of long-span steel beams. In the central bending moment area of the steel beam, the connecting rods and the steel strands are arranged between the two steel columns and axial prestress is applied. The central deflection can be reduced, the end pressure can be shared, and the stability and bearing capacity of the negative bending moment area of the beam end are improved.

Description

Technical Field

[0001] This invention belongs to the field of building engineering technology, and in particular relates to a long-span integral reinforcement device and method for the lower flange of a composite steel beam. Background Technology

[0002] To improve the compressive stability of the lower flange of steel beams, welded corner braces or welded stiffeners are often used for reinforcement. However, welding is a complex process, especially difficult to implement in pre-formed structures or in space-constrained environments. Welding can easily introduce residual stress, affecting the fatigue life of steel components and hindering later maintenance and functional adjustments. In particular, for steel beams with long lengths and significant extension of the negative bending moment region, extensive deployment of welded reinforcement components can lead to higher structural risks and construction costs.

[0003] While traditional rigid reinforcement members can improve the overall bending resistance of beams, they neglect the compressive stability of the lower flange of the steel beam, cannot constrain the angle change between the lower flange and the web, and cannot prevent the deformation development between them. Moreover, the overall reinforcement effect along the length of the steel beam is poor, especially when the steel beam is long. The reinforcement effect is mainly concentrated at the local action position of the rigid reinforcement member and cannot reduce the mid-span deflection. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a long-span integral reinforcement device and method for the lower flange of a composite steel beam. All flange upper cover plates are connected via connecting rods and steel strands, forming a continuous constraint system between multiple reinforcement areas. This method is suitable for the overall reinforcement of long-span steel beams. In the positive bending moment zone at mid-span of the steel beam, connecting rods and steel strands are arranged between two steel columns and axial prestress is applied. This reduces mid-span deflection and shares end pressure, improving the stability and load-bearing capacity of the negative bending moment zone at the beam ends. Furthermore, limiting blocks are installed between the lower flange and the web, effectively constraining the angle change between them, reducing deformation development, and further enhancing the reinforcement effect.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a long-span integral reinforcement device for the lower flange of a composite steel beam, employing the following technical solution:

[0006] A long-span integral reinforcement device for the lower flange of a composite steel beam includes a steel beam hoop plate set on two adjacent steel columns, a flange upper cover plate connected to the steel beam hoop plate, at least two flange upper cover plates independently set on the lower flange, and a detachable lower cover plate set on each flange upper cover plate.

[0007] A connecting rod is provided between two adjacent flange cover plates at the end of the lower flange, and steel strands are provided between all flange cover plates independently provided on the lower flange; a limit block is provided on each flange cover plate, and the end of the limit block away from the flange cover plate contacts the web plate.

[0008] Furthermore, the steel beam hoop plate comprises two symmetrically arranged parts, each part having a hoop plate connecting block at one end, and the hoop plate connecting block having a connecting hole; each part of the steel beam hoop plate has a flange cover plate at the end away from the hoop plate connecting block.

[0009] Furthermore, stiffening ribs are provided on the steel beam ring plate; the stiffening ribs are reinforcing plates, and multiple parallel reinforcing plates are provided in the middle of the steel beam ring plate. The reinforcing plates have a triangular structure, with the area of ​​one end closer to the flange cover plate being larger than that of the other end.

[0010] Furthermore, a connecting cover plate is provided at the end of the flange cover plate away from the web plate, and the connecting cover plate is provided with an elongated hole; a side plate is vertically provided at the end of the connecting cover plate away from the flange cover plate, and the side plate is provided with bolt connection holes.

[0011] Furthermore, a lower cover plate is detachably provided on the upper flange cover plate; a lower cover plate connecting block is provided at one end of the lower cover plate; a side plate is also vertically provided at the other end of the lower cover plate, and one end of the side plate of the lower cover plate is inserted into the elongated hole; the side plate of the lower cover plate and the side plate of the upper flange cover plate are connected by bolt connection holes and connecting bolts; both the upper flange cover plate and the lower cover plate are provided with connection holes and are connected by bolts.

[0012] Furthermore, the upper flange cover plate is provided with a lug plate, and the two ends of the lug plate are provided with connecting holes. A connecting rod is provided between two adjacent upper flange cover plates at the lower flange end through the connecting holes.

[0013] Furthermore, a prestressed anchor hole is provided in the middle of the ear plate, and steel strands are provided between all the flange cover plates independently set on the lower flange.

[0014] Furthermore, prestressing clamps are provided at both ends of the steel strand; the prestressing clamps are configured as conical structures, and the prestressing anchor holes are configured as conical structures adapted to the prestressing clamps.

[0015] Furthermore, the limiting block is disposed on the upper cover plate of the flange; the limiting block includes a side plate and a vertical plate connected to the side plate.

[0016] To achieve the above objectives, in a second aspect, the present invention also provides a long-span integral reinforcement method for the lower flange of a composite steel beam, employing the following technical solution:

[0017] A method for long-span integral reinforcement of the lower flange of a composite steel beam, using the long-span integral reinforcement device for the lower flange of a composite steel beam as described in the first aspect, includes: setting steel beam hoop plates on two adjacent steel columns, each steel beam hoop plate being connected to a flange upper cover plate; setting at least two additional flange upper cover plates independently on the lower flange, each flange upper cover plate being provided with a lower cover plate to achieve non-destructive clamping of the flange; setting a connecting rod between two adjacent flange upper cover plates at the end of the lower flange; setting steel strands between all flange upper cover plates independently set on the lower flange; and connecting all flange upper cover plates through the connecting rods and steel strands.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. This invention involves setting steel beam ring plates on two adjacent steel columns, with each steel beam ring plate connected to a flange top cover plate. At least two additional flange top cover plates are independently set on the lower flange, with a lower cover plate on each flange top cover plate, achieving non-destructive clamping of the flanges. A connecting rod is set between two adjacent flange top cover plates at the end of the lower flange, and steel strands are set between all flange top cover plates independently set on the lower flange. All flange top cover plates are connected by connecting rods and steel strands, forming a continuous constraint system between multiple reinforcement areas. This is suitable for the overall reinforcement of long-span steel beams. In the positive bending moment zone at the mid-span of the steel beam, connecting rods and steel strands are arranged between the two steel columns and axial prestress is applied, which can reduce mid-span deflection and share end pressure, improving the stability and bearing capacity of the negative bending moment zone at the beam end. Furthermore, a limiting block is set between the lower flange and the web, which can effectively constrain the angle change between the two, reduce deformation development, and further improve the reinforcement effect.

[0020] 2. This invention incorporates a limiting block between the lower flange and the web, effectively constraining the angular change between them, reducing deformation development, and further enhancing the reinforcement effect. Multiple reinforcement units, consisting of the upper and lower flange cover plates, are connected by connecting rods to form a continuous constraint system, suitable for the overall reinforcement of long-span steel beams. In the positive bending moment zone at mid-span of the steel beam, steel strands are arranged between the two devices and axial prestress is applied, which reduces mid-span deflection and shares end pressure, improving the stability and load-bearing capacity of the negative bending moment zone at the beam ends.

[0021] 3. The prestressed anchor holes of this invention adopt a tapered design, which facilitates coordinated work with anchorages and improves anchoring reliability and stress efficiency. The entire device adopts a modular design, adaptable to steel beams with different cross-sectional dimensions and different stress requirements. It can be flexibly arranged in various node scenarios, with a compact structure, small footprint, and simple and quick installation and disassembly, significantly improving construction efficiency and reducing the impact on indoor space and the original structural function. Attached Figure Description

[0022] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0023] Figure 1 This is a schematic diagram of the front structure of the device according to Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram showing the detailed structure of one side of the device according to Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the upper cover plate in Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of the lower cover plate structure of Embodiment 1 of the present invention;

[0027] Figure 5 This is a schematic diagram of the overall structure of the device according to Embodiment 1 of the present invention;

[0028] Figure 6 This is a schematic diagram of the rear structure of the device according to Embodiment 1 of the present invention;

[0029] Figure 7 This is a schematic diagram of the bottom structure of the device according to Embodiment 1 of the present invention;

[0030] Figure 8 This is a schematic diagram showing the connection between the upper cover plate and the limiting plate in Embodiment 1 of the present invention;

[0031] Figure 9 This is a schematic diagram of the steel strand and prestressed anchorage in Embodiment 1 of the present invention;

[0032] Among them, 1. Steel beam hoop plate; 2. Stiffening rib; 3. Flange upper cover plate; 4. Prestressed anchor hole; 5. Side plate; 6. Connecting upper cover plate; 7. Connecting bolt; 8. Lower cover plate; 9. Connecting hole; 10. Long hole; 11. Hoop plate connecting block; 12. Lower cover plate connecting block; 13. Limiting block; 14. Connecting rod; 15. Steel strand; 16. Prestressed clamp; 17. Steel column; 18. Lower flange; 19. Web plate. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0035] Composite steel beam: A structural member that effectively combines steel beams and concrete slabs to jointly bear loads, giving full play to the tensile strength of steel and the compressive strength of concrete.

[0036] Example 1:

[0037] In modern construction engineering, composite steel structures are widely used in multi-story and high-rise buildings. Their structural components typically include steel beams with floor slabs and highly restrained steel columns. During actual stress loading, the end regions of the steel beams are often under negative bending moment. At this time, the upper flange is under tensile stress, while the lower flange is under compression and plays a crucial role in controlling overall stability. Although the upper flange of the steel beam is usually effectively laterally restrained by floor slabs, composite slabs, or concrete slabs, significantly improving its compressive stability, the lower flange of the steel beam, lacking effective connection structures, is prone to overall flexural-torsional instability under negative bending moment.

[0038] To improve the compressive stability of the lower flange of steel beams, welded corner braces or welded stiffeners are often used for reinforcement. However, welding is a complex process, especially difficult to implement in pre-formed structures or in space-constrained environments. Welding can easily introduce residual stress, affecting the fatigue life of steel components and hindering later maintenance and functional adjustments. In particular, for steel beams with long lengths and significant extension of the negative bending moment region, extensive deployment of welded reinforcement components can lead to higher structural risks and construction costs.

[0039] As described in the background section, traditional rigid reinforcement members neglect the compressive stability of the lower flange of the steel beam, cannot constrain the angle change between the lower flange and the web, and cannot prevent the deformation development between the two; moreover, the overall reinforcement effect in the length direction of the steel beam is poor, especially when the steel beam is long, the reinforcement effect is mainly concentrated at the local action position of the rigid reinforcement member, and cannot reduce the mid-span deflection.

[0040] To solve at least one of the above problems, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 9 As shown, this embodiment provides a long-span integral reinforcement device for the lower flange of a combined steel beam, including a steel beam hoop plate 1, stiffening ribs 2, flange upper cover plate 3, prestressed anchor holes 4, side upright plates 5, connecting upper cover plate 6, connecting bolts 7, lower cover plate 8, connecting holes 9, elongated holes 10, hoop plate connecting block 11, lower cover plate connecting block 12, limiting block 13, connecting rod 14, steel strand 15, and prestressed clamps 16.

[0041] like Figure 1 As shown, a steel beam hoop plate 1 is provided on each of two adjacent steel columns 17. The steel beam hoop plate 1 is configured as a rectangular structure adapted to the steel column 17.

[0042] like Figure 1 and Figure 3 As shown, the steel beam hoop plate 1 includes two symmetrically arranged parts. Each part has a hoop plate connecting block 11 at one end. The hoop plate connecting block 11 has a connecting hole, which can be used to connect one end of the two parts of the steel beam hoop plate 1 through bolts and connecting holes. Each part of the steel beam hoop plate 1 has a flange cover plate 3 at the end away from the hoop plate connecting block 11.

[0043] The steel beam hoop plate 1 comprises two symmetrically arranged parts, which are detachably connected by the hoop plate connecting block 11, thus enabling flexible clamping of the steel column 17.

[0044] The steel beam hoop plate 1 is provided with stiffening ribs 2; specifically, the stiffening ribs 2 are reinforcing plates, and multiple parallel reinforcing plates are provided in the middle position of the steel beam hoop plate 1. The reinforcing plates have a triangular structure, with the end near the flange cover plate 3 having a larger area than the other end. The triangular structure of the reinforcing plates, with the end near the flange cover plate 3 having a larger area than the other end, can improve the reinforcement stability in the middle position.

[0045] Optionally, the height and distribution of the stiffening ribs 2 are arranged according to the stress requirements of the steel beam, which can prevent the lower flange 18 from twisting or buckling instability outside the plane.

[0046] like Figure 3 As shown, a connecting upper cover plate 6 is provided at the end of the flange upper cover plate 3 away from the web plate 19, and an elongated hole 10 is provided on the connecting upper cover plate 6; a side plate 5 is vertically provided at the end of the connecting upper cover plate 6 away from the flange upper cover plate 3, and a bolt connection hole is provided on the side plate 5.

[0047] like Figure 4 and Figure 5 As shown, a lower cover plate 8 is detachably mounted on the upper flange cover plate 3. The upper flange cover plate 3 and the lower cover plate 8 are detachably fitted to clamp the lower flange 18 of the steel beam. Pre-drilled mounting holes are provided on the upper flange cover plate 3 and the lower cover plate 8 for quick assembly, forming a closed constraint system for the steel beam flange in the negative bending moment zone. A lower cover plate connecting block 12 is provided at one end of the lower cover plate 8 for connecting two lower cover plates 8. A side upright plate 5 is also vertically mounted at the other end of the lower cover plate 8. One end of the upper side upright plate 5 of the lower cover plate 8 is inserted into the elongated hole 10, improving connection stability. The upper side upright plate 5 of the lower cover plate 8 is connected to the upper side upright plate 5 of the upper flange cover plate 3 via bolt connection holes and connecting bolts 7. Both the upper flange cover plate 3 and the lower cover plate 8 have connection holes for bolt connection.

[0048] Optionally, to address the issue of the lower flange 18 in the negative bending moment zone at the end of the steel beam being prone to instability under compression, the upper flange 3 and the lower flange 8 are used to clamp the lower flange 18 without damage. Structural adhesive is used to enhance the bonding performance between the upper flange 3 and the lower flange 18 contact surface. This achieves stable clamping and improves anti-slip performance without damaging the original steel beam structure, facilitating non-destructive reinforcement and modification of the steel beam components after the building structure is completed.

[0049] Optionally, the upper flange cover plate 3 extends outward to form the connecting upper cover plate 6. The upper flange cover plate 3 and the extension section of the lower cover plate 8 are connected by high-strength bolts and a certain preload is applied. Through friction and compression, the lower flange 18 is rigidly clamped in the plane, thereby effectively improving the steel beam's resistance to local instability in the negative bending moment section, strengthening the constraint on the lower flange 18, and preventing the lower flange 18 from becoming unstable in the plane.

[0050] The lower cover plate 8 extends with a side plate 5 as an insert plate, and is positioned by inserting it into the elongated hole 10. The end of the insert plate is bolted to the side plate 5 on the upper cover plate 3 of the flange, and lower cover plate connecting blocks 12 are set on both sides of the beam to form multi-point pressure constraint. This structural design forms a complete transverse force ring, making the connection between the upper cover plate 3 of the flange and the lower cover plate 8 and the steel beam component more stable and reliable.

[0051] like Figure 2 and Figure 3 As shown, the upper flange cover plate 3 is provided with a lug plate, and the two ends of the lug plate are provided with connecting holes 9. A connecting rod 14 is provided between two adjacent upper flange cover plates 3 at the end of the lower flange 18 through the connecting holes 9 and nuts, etc.

[0052] The upper flange cover plate 3 and the lower flange cover plate 8 are connected by connecting rods 14 through connecting holes 9. The entire lower flange 18 is systematically reinforced by a multi-point closed constraint system arranged in the negative bending moment section. The connecting holes 9 adopt a symmetrical double-hole structure to improve the connection stiffness and stability.

[0053] like Figure 8 and Figure 9 As shown, at least two flange upper cover plates 3 are independently provided on the lower flange 18, and a detachable lower cover plate 8 is provided on each flange upper cover plate 3; a prestressed anchor hole 4 is provided in the middle of the ear plate, and steel strands 15 are provided between all flange upper cover plates 3 independently provided on the lower flange 18; a connecting rod 14 and steel strands 15 are arranged between the two steel columns 17 and axial prestress is applied, which can reduce the mid-span deflection and share the end pressure, thereby improving the stability and bearing capacity of the negative bending moment zone at the beam end.

[0054] like Figure 9As shown, prestressed clamps 16 are provided at both ends of the steel strand 15; the prestressed clamps 16 are installed on the steel strand 15 by clamping, interference fit, or welding. The prestressed clamps 16 are configured with a conical structure, and the prestressed anchor holes 4 are configured with a conical structure adapted to the prestressed clamps 16 to ensure connection stability.

[0055] Optionally, between two devices symmetrically arranged on both sides of the positive bending moment zone of the steel beam, the prestressed anchor hole 4 is connected to the steel strand 15 to apply axial prestress, forming a downward deflection resistance to the middle section of the steel beam; wherein the prestressed anchor hole 4 adopts an inverted frustum structure design to improve the clamping performance and anchoring efficiency of the anchoring system and enhance the overall stress effect. The inverted frustum shape of the prestressed anchor hole 4 facilitates clamping with the prestressed clamp 16.

[0056] like Figure 1 As shown, the limiting block 13 is disposed on the flange cover plate 3 and can be connected by bolts; the limiting block 13 has a side plate and a vertical plate connected to the side plate, and the vertical plate is in contact with the web plate 19.

[0057] Optionally, the limiting block 13 is connected to the connecting hole 9 via the connecting rod 14 and the nut. The upper part is supported on both sides of the web plate 19 by the enlarged flat end plate. By limiting the angle between the lower flange 18 and the web plate 19 on both sides, the deformation between the two is limited, thereby improving the stability of the lower flange 18.

[0058] This embodiment enables a prefabricated reinforcement device that allows for non-destructive clamping of the lower flange of steel beams, can be connected and combined, and has the function of applying prestress. It can not only meet the stability requirements of the lower flange in the negative bending moment zone at the end of the steel beam, but also improve the overall bearing capacity of the positive bending moment zone in the middle of the steel beam. It has important engineering significance for improving the reliability, durability and convenience of later maintenance of building steel structures.

[0059] One of the working processes or principles of this embodiment is as follows:

[0060] S1. Select the appropriate flange cover plate 3, place the connecting flange cover plate 3 on the upper part of the lower flange 18, and bond them together with adhesive. At this time, the connecting cover plate 6 is placed in the corresponding position, the steel beam hoop plate 1 surrounds the steel column 17, and the two flange cover plates 3 are connected on the other side by the hoop plate connecting block 11 and bolts.

[0061] S2. Pass one end of the side upright plate 5 on the lower cover plate 8 through the elongated hole 10 and bond it to the lower surface of the lower flange 18 with adhesive. The side upright plate 5 on the lower cover plate 8 is connected to the side upright plate 5 on the upper cover plate 3 of the flange, and the lower cover plate 8 is connected to the connecting upper cover plate 6 with bolts. The two lower cover plates 8 are connected by the lower cover plate connecting block 12 and bolts.

[0062] S3. The limiting block 13 is connected to the connecting hole 9 through the connecting rod 14 and the nut, and the upper part is supported on both sides of the web plate 19 by the flat end plate.

[0063] S4. If necessary, install the upper cover plate 3 and lower cover plate 8 of the flange of the other non-connected steel beam hoop plate 1 according to the above steps, pass the connecting rod 14 through the adjacent connecting holes 9 in sequence, and tighten the bolts.

[0064] S5. If necessary, pass the steel strand 15 through the prestressed anchor hole 4, install the anchor to apply prestress, and lock the prestressed clamp 16.

[0065] This embodiment employs a structure where the lower flange 18 is non-destructively clamped by the upper flange cover plate 3 and the lower flange cover plate 8. Structural adhesive is applied to the clamping surfaces, and high-strength bolts are used to apply preload, forming a friction-compression combined constraint. This avoids residual stress and high-temperature deformation caused by welding, reduces fatigue stress in the steel beam during long-term service, and minimizes the impact on the original component's load-bearing performance without cutting or drilling. Both ends of the device are connected to the steel column 17 via steel beam hoop plates 1, and stiffening ribs 2 are provided to form a closed lateral constraint system, improving the critical stability bearing capacity of the lower flange 18 in the negative bending moment region and preventing local buckling and overall instability.

[0066] Meanwhile, in this embodiment, a limiting block 13 is set between the lower flange 18 and the web 19, which can effectively constrain the angle change between the two, reduce deformation development, and further improve the reinforcement effect. The multiple reinforcement units composed of the upper flange 3 and the lower flange 8 are spliced ​​together by connecting rods 14 to form a continuous constraint system, which is suitable for the overall reinforcement of long-span steel beams. In the positive bending moment zone at the mid-span of the steel beam, steel rods or steel strands 15 are arranged between the two devices and axial prestress is applied, which can reduce the mid-span deflection and share the end pressure, thereby improving the stability and bearing capacity of the negative bending moment zone at the beam end.

[0067] Furthermore, the prestressed anchor hole 4 adopts an inverted frustum (conical) design, which facilitates its coordinated operation with the anchorage, improving anchoring reliability and stress efficiency. The entire device adopts a modular design, adapting to steel beams with different cross-sectional dimensions and different stress requirements. It can be flexibly arranged in various node scenarios, with a compact structure, small footprint, and simple and quick installation and disassembly, significantly improving construction efficiency and reducing the impact on indoor space and the original structural function.

[0068] In summary, compared with existing reinforcement methods, this embodiment not only achieves efficient and non-destructive reinforcement of the lower flange 18, but also has the combined effects of increased load-bearing capacity, deflection control and enhanced stability.

[0069] Example 2:

[0070] This embodiment provides a long-span integral reinforcement method for the lower flange of a composite steel beam, using the long-span integral reinforcement device for the lower flange 18 of the composite steel beam as described in Embodiment 1. The method includes: steel beam hoop plates 1 are installed on two adjacent steel columns 17, each steel beam hoop plate 1 is connected to a flange upper cover plate 3, and at least two additional flange upper cover plates 3 are independently installed on the lower flange 18, each flange upper cover plate 3 is equipped with a lower cover plate 8 to achieve non-destructive clamping of the flange; a connecting rod 14 is installed between two adjacent flange upper cover plates 3 at the end of the lower flange 18, and steel strands 15 are independently installed between all flange upper cover plates 3 on the lower flange 18; all flange upper cover plates 3 are connected by the connecting rod 14 and the steel strands 15.

[0071] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A long-span integral reinforcement device for the lower flange of a composite steel beam, characterized in that, It includes a steel beam hoop plate set on two adjacent steel columns, a flange top cover plate connected to the steel beam hoop plate, at least two flange top cover plates set independently on the lower flange, and a detachable lower cover plate set on each flange top cover plate; A connecting rod is provided between two adjacent flange cover plates at the end of the lower flange, and a steel strand is provided between all flange cover plates independently provided on the lower flange; a limit block is provided on each flange cover plate, and the end of the limit block away from the flange cover plate contacts the web plate. The flange upper cover plate has a connecting upper cover plate at one end away from the web plate, and the connecting upper cover plate has an elongated hole; the connecting upper cover plate has a side plate vertically arranged at the other end away from the flange upper cover plate, and the side plate has bolt connection holes; one end of the lower cover plate has a lower cover plate connecting block for connecting two lower cover plates; lower cover plate connecting blocks are arranged on both sides of the beam to form multi-point pressure constraint; the other end of the lower cover plate also has a side plate vertically arranged, and one end of the side plate of the lower cover plate is inserted into the elongated hole; the side plate of the lower cover plate and the side plate of the flange upper cover plate are connected by bolt connection holes and connecting bolts; both the flange upper cover plate and the lower cover plate have connection holes for bolt connection.

2. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 1, characterized in that, The steel beam hoop plate comprises two symmetrically arranged parts, each part having a hoop plate connecting block at one end, and the hoop plate connecting block having a connecting hole; each part of the steel beam hoop plate has a flange cover plate at the end away from the hoop plate connecting block.

3. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 2, characterized in that, The steel beam hoop plate is provided with stiffening ribs; the stiffening ribs are reinforcing plates, and multiple parallel reinforcing plates are provided in the middle of the steel beam hoop plate. The reinforcing plates have a triangular structure, with the area of ​​one end closer to the flange cover plate being larger than the other end.

4. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 1, characterized in that, The upper flange cover plate is provided with a lug plate, and the two ends of the lug plate are provided with connecting holes. A connecting rod is provided between two adjacent upper flange cover plates at the lower flange end through the connecting holes.

5. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 4, characterized in that, The ear plate is provided with a prestressed anchor hole in the middle, and steel strands are provided between all the flange cover plates that are independently set on the lower flange.

6. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 5, characterized in that, The steel strand is provided with prestressed clamps at both ends; the prestressed clamps are configured as conical structures, and the prestressed anchor holes are configured as conical structures adapted to the prestressed clamps.

7. The long-span integral reinforcement device for the lower flange of a composite steel beam as described in claim 1, characterized in that, The limiting block includes a side plate and a vertical plate connected to the side plate.

8. A method for long-span integral reinforcement of the lower flange of a composite steel beam, characterized in that, The long-span integral reinforcement device for the lower flange of the composite steel beam as described in any one of claims 1-7 includes: steel beam hoop plates installed on two adjacent steel columns, each steel beam hoop plate being connected to a flange upper cover plate; at least two additional flange upper cover plates independently installed on the lower flange, each flange upper cover plate being provided with a lower cover plate to achieve non-destructive clamping of the flange; a connecting rod installed between two adjacent flange upper cover plates at the end of the lower flange; steel strands installed between all flange upper cover plates independently installed on the lower flange; and all flange upper cover plates connected by the connecting rods and steel strands.

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