A building layer lengthening column joint reinforcing device and a construction method thereof

Abstract

This invention discloses a reinforcement device and construction method for column joints in building additions, belonging to the field of building structure reinforcement and renovation technology. It includes an upper steel clamp assembly, a lower steel clamp assembly, vertical high-strength tie bolts, and horizontal high-strength tie bolts. The upper steel clamp assembly is entirely wrapped around the bottom of the newly added column, with high-strength non-shrink grout injected between them. The lower steel clamp assembly is entirely wrapped around the top of the original structural column and the ends of the surrounding roof beams, with high-strength non-shrink grout injected between them. The lower steel clamp assembly has recessed grooves corresponding to the ends of each roof beam, with horizontal high-strength tie bolts penetrating the roof beams through steel plates on both sides of the recessed grooves. The vertical high-strength tie bolts penetrate the upper steel clamp assembly, the floor slab, and the lower steel clamp assembly, locking and fixing them to form a continuous closed steel constraint system spanning the floor slab. This invention solves the problems of traditional reinforcement systems, such as avoiding the floor slab, disconnection of upper and lower constraints, inability of the newly added column and the original structure to cooperate in bearing loads, weak shear resistance at the beam ends, and severe damage to the original structure.

Description

Technical Field

[0001] This invention belongs to the field of reinforcement and renovation technology of existing building concrete structures, specifically relating to a reinforcement device for building extension column joints and its construction method. Background Technology

[0002] With the increasing demand for renovation and expansion of existing concrete frame buildings such as data centers and industrial plants, equipment platforms, mezzanines, or new columns are often added to the roof. The increased vertical loads are concentrated on the roof beam-column joints, which can easily lead to insufficient bearing capacity at the top of the original columns and the ends of the beams, and failure to meet the seismic performance of the joints. Therefore, it is necessary to strengthen and reinforce the beam-column joints.

[0003] Currently, the mainstream reinforcement methods are divided into three categories: external concrete encapsulation to increase the cross-section, external steel encapsulation, and steel hoop reinforcement, all of which have obvious shortcomings. External concrete encapsulation to increase the cross-section requires large-area chiseling of floor slabs and rebar installation in beams and columns, causing significant damage to the original structure. The process is complex, the curing period is long, and the added self-weight will increase the load on the original structure. External steel encapsulation only wraps the original columns or beams individually, and the reinforced components are independent of each other. During construction, the steel hoop needs to be disconnected at the floor slab location to avoid the floor slab, which cannot form continuous constraint through the floor slab. The new columns, floor slabs, and original beams and columns cannot work together to bear the load, the force transmission path at the nodes is broken, and the overall stiffness improvement is limited. The existing steel sleeve reinforcement still follows the approach of avoiding the floor slab. The upper and lower sections of the steel sleeve are independent and do not adapt to the needs of adding new columns for building additions. The floor slab only serves as a construction obstacle and does not participate in the joint stress. The beam ends are simply wrapped with steel plates, lacking reliable shear resistance structure. Under seismic action, the beam ends are prone to shear failure. The stiffness of the steel sleeve segment overlap is weak, the grouting is uneven, and the working effect of the new and old structures is poor.

[0004] In summary, existing technologies cannot simultaneously address the multiple requirements of extending new columns, reinforcing existing beams and columns, coordinating floor slab stress, minimizing construction damage, and improving the seismic performance of joints. They suffer from poor reinforcement reliability, low construction efficiency, and significant damage during retrofitting. Therefore, there is an urgent need to develop a building addition column joint reinforcement device that can clamp the floor slab, achieve integrated wrapping of columns, beams, and slabs, and also function as a column extension device. This device should optimize the force transmission path and improve the overall integrity and seismic bearing capacity of the joint while minimizing damage to the original structure. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a reinforcement device and construction method for column joints in building additions, addressing the shortcomings of existing technologies. This invention solves the problems of traditional reinforcement systems, such as avoiding floor slabs, disconnection of upper and lower constraints, inability of new columns to cooperate with the original structure in bearing load, weak shear resistance at beam ends, and severe damage to the original structure. It achieves integrated clamping and constraint of new columns, original structural columns, roof beams, and floor slabs, forming a continuous closed force-bearing system that spans the floor slabs. It has the dual functions of column extension and joint reinforcement, significantly improving the integrity, shear bearing capacity, and seismic ductility of beam-column joints. The construction is convenient and causes minimal damage to the original building.

[0006] The technical solution adopted by this invention to solve its technical problem is: a reinforcement device for the joint of a building extension column, comprising an upper steel sleeve assembly, a lower steel sleeve assembly, vertical high-strength tie bolts, and horizontal high-strength tie bolts; the upper steel sleeve assembly is entirely wrapped around the bottom of the newly added column, and a grouting gap is reserved between the inner wall of the upper steel sleeve assembly and the outer wall of the newly added column, and high-strength non-shrink grout is injected to achieve overall bonding and force transmission between the upper steel sleeve assembly and the newly added column; the lower steel sleeve assembly is entirely wrapped around the top of the original structural column and the ends of the surrounding roof beams, and a grouting gap is reserved between the inner wall of the lower steel sleeve assembly and the outer walls of the original structural column and the surrounding roof beams. High-strength, non-shrink grout is injected; the lower steel clamp assembly has notches corresponding to the ends of each roof beam, and transverse high-strength tie bolts are inserted through the steel plates on both sides of the notches, which constrain the concrete at the ends of the roof beams, greatly improving the shear bearing capacity at the ends of the roof beams; the upper steel clamp assembly is arranged on the upper surface of the floor slab, and the lower steel clamp assembly is arranged on the lower surface of the floor slab, with the floor slab sandwiched between the upper and lower steel clamp assemblies; the vertical high-strength tie bolts pass through the upper steel clamp assembly, the floor slab, and the lower steel clamp assembly and are locked in place, forming a continuous closed steel constraint system spanning the floor slab.

[0007] Furthermore, the upper steel clamp assembly includes a rectangular annular steel plate I, four upper vertical steel plates, and twelve stiffening plates; the internal net dimension of the rectangular annular steel plate I is larger than the outer contour dimension of the new column section; the upper horizontal plate of the rectangular annular steel plate I is broken on the right side and the lower horizontal plate is broken on the left side, forming an assembly opening, which facilitates direct wrapping and fitting onto the outside of the new column on site; each end of the upper and lower horizontal plates of the rectangular annular steel plate I has a circular through hole I for vertical high-strength tie bolts to pass through; the four upper vertical steel plates are vertically welded to the four sides of the inner side of the rectangular annular steel plate I; before assembly, the two upper vertical steel plates at the unbroken corner of the rectangular annular steel plate I are welded together on their sides, and the two upper vertical steel plates at the broken corner of the rectangular annular steel plate I are not welded on their sides; three stiffening plates are welded at equal intervals between each upper vertical steel plate and the rectangular annular steel plate I as a stiffening structure to improve the overall bending and lateral stiffness of the upper steel clamp and prevent the steel plate from buckling and deforming under stress.

[0008] Furthermore, the thickness of the rectangular annular steel plate I is 10mm to 20mm; the thickness of the upper vertical steel plate is 8mm to 16mm; and the thickness of the stiffening plate is 6mm to 12mm.

[0009] Furthermore, the lower steel clamp assembly includes a rectangular annular steel plate II, four lower vertical steel plates, and four notches; the thickness, internal net dimensions, assembly and disassembly structure, and opening form of the rectangular annular steel plate II are completely consistent with those of the rectangular annular steel plate I; the four lower vertical steel plates are vertically welded to the four inner sides of the rectangular annular steel plate II. Before assembly, the sides of the two lower vertical steel plates located at the undisassembled corners of the rectangular annular steel plate II are welded together, while the sides of the two lower vertical steel plates located at the disassembled corners of the rectangular annular steel plate II are not welded; the upper half of each of the four lower vertical steel plates... An integral notch is provided, the top of which is flush with the top surface of the lower vertical steel plate. The net internal size of the notch is slightly larger than the cross-sectional size of the roof beam, allowing the end of the original structural beam to be inserted into the notch for containment and restraint. An avoidance groove is provided in the overlapping area of ​​the rectangular annular steel plate II and the lower vertical steel plate corresponding to the notch to ensure the integrity of the beam. Two sets of transverse circular holes are provided on the steel plates on both sides of a single notch, and a transverse high-strength tie bolt is inserted through each set of transverse circular holes. The transverse high-strength tie bolt penetrates the concrete at the end of the roof beam, forming a two-way shear restraint at the beam end.

[0010] Furthermore, the thickness of the rectangular annular steel plate II is 10mm to 20mm; the thickness of the lower vertical steel plate is 8mm to 16mm.

[0011] Furthermore, the grouting gaps between the upper steel sleeve assembly and the newly added column, the lower steel sleeve assembly and the original structural column, and the outer wall of the surrounding roof beams are uniformly controlled to be 20mm to 50mm. If the gap is too small, the grouting material cannot fill the gap, and if it is too large, it will easily cause local instability of the steel sleeve.

[0012] Furthermore, all steel components are welded using full welding, with a weld height of not less than 6mm.

[0013] The present invention also provides a construction method for the above-mentioned building addition and extension column joint reinforcement device, comprising the following steps: S1: All steel components are prefabricated in the factory and anti-corrosion treatment is completed; after arrival on site, the loose layer on the surface of the original beams and columns is cleaned and polished smooth. S2: Make circular holes in the floor slab corresponding to the positions of the vertical bolt holes of the upper and lower steel sleeve components; S3: The new column is formed by casting and molding. After the new column has reached the design strength, the upper steel sleeve assembly is separated along the assembly opening and wrapped around the bottom of the new column from the left and right sides. All assembly gaps of the upper steel sleeve are fully welded and sealed. S4: Separate the lower steel sleeve assembly along the assembly opening, wrap it around the top of the original structural column from the left and right sides, so that all the ends of the roof beams around the perimeter are embedded in the corresponding recessed grooves, install the horizontal high-strength tie bolts through the ends of each beam and tighten them initially; fully weld and seal all splicing positions of the lower steel sleeve assembly. S5: Align the vertical bolt holes of the upper and lower steel sleeve components, insert all the vertical high-strength tie bolts, and tighten them evenly in stages to make the upper and lower steel sleeve components clamp the middle floor slab, so that the floor slab participates in the overall force constraint. S6: Seal the grouting gaps on the sides and bottom of the lower steel sleeve assembly, install grouting nozzles and venting nozzles, and inject high-strength non-shrink grout into the gaps between the upper steel sleeve assembly, the lower steel sleeve assembly and the concrete component. After the grout has cured to the design strength, the reinforcement construction is completed.

[0014] Furthermore, all steel components undergo shot blasting to remove rust at grade Sa2.5, followed by two coats of epoxy anti-rust primer with a dry film thickness ≥60μm. In humid environments, an additional topcoat can be applied for corrosion protection, enhancing the durability of outdoor roofing.

[0015] Furthermore, the high-strength non-shrink grout has a compressive strength of ≥60MPa after 28 days of standard curing, and possesses micro-expansion and non-shrinkage properties, ensuring a tight bond between the steel sleeve and the concrete and seamless force transmission.

[0016] Compared with existing traditional technologies such as external steel cladding, increased cross-section, and separate steel hoop reinforcement, this invention has the following advantages: 1. Integrated continuous closed constraint, floor slab co-force: The floor slab is clamped by upper and lower steel sleeve components and locked by vertical high-strength tie bolts to form an overall closed steel constraint spanning the floor slab, abandoning the traditional design idea of ​​reinforcing and avoiding the floor slab; the floor slab is incorporated into the force-bearing system as an intermediate force-transmitting component, the overall stiffness of the node is greatly improved, the force transmission path is continuous and complete, and the force dispersion defects caused by floor slab partitions are eliminated.

[0017] 2. Simultaneously achieves dual functions of adding new column extension and reinforcing the original beam-column joint: the upper steel sleeve component wraps the bottom of the new column to achieve reliable vertical extension, and the lower steel sleeve component wraps the top of the original column and the ends of the surrounding beams to reinforce the original structure. One device solves the problem of insufficient load-bearing capacity of the connection between the new column and the original joint in the roof addition at the same time. It is suitable for the core working conditions of adding platforms and mezzanine floors on the roof of factories and data centers, and has strong application scenario targeting.

[0018] 3. The two-way tension shear structure at the beam end significantly improves seismic performance: The lower steel sleeve assembly is equipped with an integrated notch to wrap around the beam end, and is paired with transverse double-layer high-strength tie bolts that penetrate the beam body, forming a two-way constraint on the beam end concrete. This effectively inhibits the development of shear diagonal cracks at the beam end under seismic loads, greatly improves the shear bearing capacity and ductility of the core area of ​​the node, and meets the renovation needs of high seismic fortification areas.

[0019] 4. Minimal damage to the original structure and high construction efficiency: No need for large-area removal of floor slabs or extensive rebar installation in beams and columns; the steel sleeve assembly adopts an open assembly structure, eliminating the need for large hoisting equipment on site, and the wet operation only involves grouting, resulting in a short curing period. Compared with external concrete reinforcement, the construction period is shortened by more than 50%, and the overall renovation cost is lower.

[0020] 5. High overall rigidity, strong resistance to deformation and bulging: The upper steel sleeve assembly is equipped with multiple equidistant stiffening plates as stiffening ribs. The ring steel plate and the vertical steel plate form a three-dimensional steel frame, which is not easy to bend and deform locally after being stressed. The grouting gap is standardized and controllable. The high-strength micro-expansion grouting material ensures tight bonding between the steel and concrete interface, and the new and old structures work together well.

[0021] 6. Excellent durability and suitable for open-air, damp roof environments: All steel components undergo standardized shot blasting and anti-corrosion primer treatment. The steel component thickness range is reasonable, and the anti-corrosion system is complete. It can be used for a long time in harsh environments such as outdoor roofs and high-humidity industrial plants, reducing the cost of later maintenance.

[0022] This invention is particularly suitable for data centers, industrial plants, roof additions to old frame buildings, the addition of equipment platforms, and the addition of mezzanine floors. It integrates the reinforcement and strengthening of the original concrete beam-column joints with the newly added columns, and can simultaneously achieve multiple functions such as improving the load-bearing capacity of the original structure, reliably extending the new columns, and enhancing the seismic performance of the joints. Attached Figure Description

[0023] Figure 1 This is a completed installation diagram of the building extension column joint reinforcement device of the present invention; Figure 2 This is a schematic diagram of the overall structure of the building extension column node reinforcement device of the present invention; Figure 3 This is a schematic diagram of the steel sleeve assembly structure of the building extension column node reinforcement device of the present invention; Figure 4 This is a schematic diagram of the lower steel sleeve assembly structure of the building addition extension column node reinforcement device of the present invention; Figure 5 This is a schematic diagram of the vertical cross-sectional structure of the node in this invention; Explanation of the reference numerals in the figure: 100. Upper steel sleeve assembly; 110. Rectangular annular steel plate I; 111. Circular through hole I; 120. Upper vertical steel plate; 130. Rib plate; 200. Lower steel sleeve assembly; 210. Rectangular annular steel plate II; 211. Circular through hole II; 220. Lower vertical steel plate; 230. Notch groove; 231. Horizontal circular hole. 3. Vertical high-strength tie bolts; 4. High-strength transverse tie bolts. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Please see Figures 1 to 5 This embodiment provides a reinforcement device for the joint of a building extension column, including an upper steel sleeve assembly 100, a lower steel sleeve assembly 200, vertical high-strength tie bolts 3, and horizontal high-strength tie bolts 4. The upper steel sleeve assembly 100 is entirely wrapped around the bottom of the newly added column. A grouting gap is reserved between the inner wall of the upper steel sleeve assembly 100 and the outer wall of the newly added column, and high-strength non-shrink grout is injected to achieve overall bonding and force transfer between the upper steel sleeve assembly 100 and the newly added column. The lower steel sleeve assembly 200 is entirely wrapped around the top of the original structural column and the ends of the surrounding roof beams. A grouting gap is reserved between the inner wall of the lower steel sleeve assembly 200 and the outer walls of the original structural column and the surrounding roof beams, and high-strength non-shrink grout is injected. The lower steel clamp assembly 200 is provided with a notch 230 at the end of each roof beam. A transverse high-strength tie bolt 4 is inserted through both sides of the notch 230, which constrains the concrete at the end of the roof beam, thereby significantly improving the shear bearing capacity at the end of the roof beam. The upper steel clamp assembly 100 is arranged on the upper surface of the floor slab, and the lower steel clamp assembly 200 is arranged on the lower surface of the floor slab. The floor slab is sandwiched between the upper steel clamp assembly 100 and the lower steel clamp assembly 200. The vertical high-strength tie bolt 3 vertically penetrates the upper steel clamp assembly 100, the floor slab, and the lower steel clamp assembly 200 and is locked and fixed, forming a continuous closed steel constraint system spanning the floor slab.

[0026] In this embodiment, the upper steel sleeve assembly 100 includes a rectangular annular steel plate I110, four upper vertical steel plates 120, and twelve reinforcing plates 130; the rectangular annular steel plate I110 is 14mm thick, and its internal net size is larger than the outer contour size of the new column section; the upper horizontal plate of the rectangular annular steel plate I110 is broken on the right side, and the lower horizontal plate is broken on the left side, forming an assembly opening, which facilitates direct wrapping and sleeve application to the outside of the new column on site; each end of the upper and lower horizontal plates of the rectangular annular steel plate I110 has a circular through hole I111 for vertical high-strength tie bolts to pass through; the four upper... The vertical steel plate 120 is 10mm thick and is vertically welded to the four sides of the inner side of the rectangular annular steel plate I110. Before assembly, the two upper vertical steel plates 120 located at the corners of the rectangular annular steel plate I110 that are not broken are welded to each other, while the two upper vertical steel plates 120 located at the corners of the rectangular annular steel plate I110 that are broken are not welded to each other. Three stiffening plates 130 with a thickness of 10mm are welded at equal intervals between each upper vertical steel plate 120 and the inner wall of the rectangular annular steel plate I110 as a stiffening structure to improve the overall bending and lateral stiffness of the upper steel sleeve assembly 100 and prevent the steel plate from bulging and deforming under stress.

[0027] In this embodiment, the lower steel clamp assembly 200 includes a rectangular annular steel plate II 210, four lower vertical steel plates 220, and four notches 230. The thickness, internal net dimensions, assembly and disassembly structure, and opening form of the rectangular annular steel plate II 210 are completely consistent with those of the rectangular annular steel plate I 110. The four lower vertical steel plates 220 are 10mm thick and are vertically welded to the four inner sides of the rectangular annular steel plate II 210. Before assembly, the sides of the two lower vertical steel plates 220 located at the undisassembled corners of the rectangular annular steel plate II 210 are welded together, while the sides of the two lower vertical steel plates 220 located at the disassembled corners of the rectangular annular steel plate II 210 are not welded. The four lower vertical steel plates 220... Each part of the upper section is integrally provided with a notch 230. The top of the notch 230 is flush with the top surface of the lower vertical steel plate 220. The net internal size of the notch 230 is slightly larger than the cross-sectional size of the roof beam, so that the end of the original roof beam can be inserted into the notch 230 for enclosure and restraint. The rectangular ring steel plate II 210 and the lower vertical steel plate 200 have avoidance slots in the overlapping area of ​​the notch 230 to ensure the integrity of the beam. Two sets of transverse circular holes 231 are opened on the steel plates on both sides of a single notch 230. A transverse high-strength tie bolt 4 is inserted through each set of transverse circular holes 231. The transverse high-strength tie bolt 4 penetrates the concrete at the end of the roof beam to form a two-way shear restraint at the beam end.

[0028] In this embodiment, the grouting gaps between the upper steel sleeve assembly 100 and the newly added column, the lower steel sleeve assembly 200 and the original structural column, and the outer walls of the surrounding roof beams are all controlled at 35mm. If the gap is too small, the grouting material cannot fill completely; if it is too large, it can easily cause local instability of the steel sleeve. Specifically, C60 high-strength, non-shrink grouting material is used for filling.

[0029] In this embodiment, all steel components are welded using full welding, and the weld height is not less than 6mm.

[0030] In this embodiment, the vertical high-strength tie bolt 3 is an M24, 8.8 grade high-strength bolt, equipped with a high-strength flat washer and a spring washer; the horizontal high-strength tie bolt 4 is an M20, 8.8 grade high-strength bolt, equipped with a high-strength flat washer and a spring washer.

[0031] The construction method of the building addition and extension column joint reinforcement device described in this embodiment includes the following steps: S1: All steel components are prefabricated in the factory and anti-corrosion treatment is completed; after arrival on site, the loose layer on the surface of the original beams and columns is cleaned and polished smooth. S2: Make circular holes in the floor slab corresponding to the positions of the vertical bolt holes of the upper and lower steel sleeve components; S3: The new column is formed by casting and molding. After the new column has reached the design strength, the upper steel sleeve assembly is separated along the assembly opening and wrapped around the bottom of the new column from the left and right sides. All assembly gaps of the upper steel sleeve are fully welded and sealed. S4: Separate the lower steel sleeve assembly along the assembly opening, wrap it around the top of the original structural column from the left and right sides, so that the ends of all the roof beams around the perimeter are embedded in the corresponding recessed grooves, install the horizontal high-strength tie bolts through the ends of each beam and tighten them initially; fully weld and seal all splicing and welding positions of the lower steel sleeve assembly. S5: Align the vertical bolt holes of the upper and lower steel sleeve components, insert all the vertical high-strength tie bolts, and tighten them evenly in stages to make the upper and lower steel sleeve components clamp the middle floor slab, so that the floor slab participates in the overall force constraint. S6: Seal the grouting gaps on the sides and bottom of the lower steel sleeve assembly, install grouting nozzles and venting nozzles, and inject high-strength non-shrink grout into the gaps between the upper and lower steel sleeve assemblies and the concrete components. After the grout has been cured to the required standard, the beam-column joint reinforcement construction is completed.

[0032] All steel components undergo shot blasting to remove rust at grade Sa2.5, and are coated with two coats of epoxy anti-rust primer with a dry film thickness of ≥60μm. In humid environments, a topcoat can be added for corrosion protection to improve the durability of outdoor roofs.

[0033] The high-strength, non-shrink grout has a compressive strength of ≥60MPa after 28 days of standard curing. It has micro-expansion and non-shrinkage properties, ensuring a tight bond between the steel sleeve and the concrete and seamless force transmission.

[0034] This embodiment is applied to the renovation project of new equipment columns on the roof of an industrial plant. After reinforcement, the bearing capacity of the nodes is increased by more than 45%, and the shear bearing capacity of the beam ends is increased by 60%. There is no need to remove a large area of ​​the floor slab. The construction period is shortened by half compared with the traditional external concrete wrapping. The overall seismic performance meets the requirements of the secondary seismic frame renovation code.

[0035] This invention uses separate upper and lower steel sleeves to wrap the bottom of the new column and the original beam-column joint, respectively, with the floor slab as the intermediate force transmission medium. A continuous, closed constraint system spanning the floor slab is formed by locking and clamping with vertical high-strength tie bolts. The lower steel sleeve assembly, equipped with a notch and horizontal high-strength tie bolts, forms a bidirectional shear constraint on the beam end. High-strength, non-shrink grout is injected between the upper and lower steel sleeve assemblies and the concrete components to achieve tight bonding and force transmission between the steel and concrete. A reinforced annular steel plate enhances the overall rigidity of the steel sleeve, eliminating the force transmission disruption defects caused by traditional reinforcement methods that avoid the floor slab. This allows the new column, the original column, the roof beam, and the floor slab to form a unified and collaborative force-bearing whole, achieving reliable vertical extension of the new column and strengthening the bearing capacity and seismic ductility of the core area of ​​the beam-column joint. Simultaneously, it achieves low-damage, high-efficiency prefabricated reinforcement construction.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A reinforcement device for extending column joints in building additions, characterized in that: The system includes an upper steel clamp assembly, a lower steel clamp assembly, vertical high-strength tie bolts, and horizontal high-strength tie bolts. The upper steel clamp assembly is integrally wrapped around the bottom of the newly added column, with a pre-reserved grouting gap between the inner wall of the upper steel clamp assembly and the outer wall of the newly added column, which is then filled with high-strength non-shrink grout. The lower steel clamp assembly is integrally wrapped around the top of the original structural column and the ends of the surrounding roof beams, with a pre-reserved grouting gap between the inner wall of the lower steel clamp assembly and the outer walls of the original structural column and the surrounding roof beams, which is then filled with high-strength non-shrink grout. The lower steel clamp assembly has a notch at the end of each roof beam, and high-strength horizontal tie bolts are inserted through the steel plates on both sides of the notch to penetrate the ends of the roof beams. The upper steel clamp assembly is arranged on the upper surface of the floor slab, and the lower steel clamp assembly is arranged on the lower surface of the floor slab. The floor slab is sandwiched between the upper and lower steel clamp assemblies. The vertical high-strength tie bolts penetrate the upper steel clamp assembly, the floor slab, and the lower steel clamp assembly and are locked in place to form a continuous closed steel constraint system spanning the floor slab.

2. The reinforcement device for extending column joints in building additions according to claim 1, characterized in that: The upper steel clamp assembly includes a rectangular annular steel plate I, four upper vertical steel plates, and twelve stiffening plates. The internal net dimension of the rectangular annular steel plate I is larger than the outer contour dimension of the newly added column section. The upper horizontal plate of the rectangular annular steel plate I is broken on the right side, and the lower horizontal plate is broken on the left side, forming an assembly opening. A circular through hole I is opened at each end of the upper and lower horizontal plates of the rectangular annular steel plate I for vertical high-strength tie bolts to pass through. The four upper vertical steel plates are vertically welded to the four sides of the inner side of the rectangular annular steel plate I. Before assembly, the two upper vertical steel plates at the unbroken corner of the rectangular annular steel plate I are welded to each other on the sides, and the two upper vertical steel plates at the broken corner of the rectangular annular steel plate I are not welded on the sides. Three stiffening plates are welded at equal intervals between each upper vertical steel plate and the rectangular annular steel plate I as a stiffening structure.

3. The reinforcement device for extending column joints in building additions according to claim 2, characterized in that: The thickness of the rectangular annular steel plate I is 10mm to 20mm; the thickness of the upper vertical steel plate is 8mm to 16mm; and the thickness of the stiffening plate is 6mm to 12mm.

4. The reinforcement device for extending column joints in building additions according to claim 3, characterized in that: The lower steel sleeve assembly includes a rectangular annular steel plate II, four lower vertical steel plates, and four notches; the thickness, internal net dimensions, assembly and disassembly structure, and opening form of the rectangular annular steel plate II are completely consistent with those of the rectangular annular steel plate I; the four lower vertical steel plates are vertically welded to the four inner sides of the rectangular annular steel plate II. Before assembly, the two lower vertical steel plates located at the undisassembled corners of the rectangular annular steel plate II are welded together on their sides, while the two lower vertical steel plates located at the disassembled corners of the rectangular annular steel plate II are not welded on their sides. Each of the four lower vertical steel plates has an integral notch on its upper half. The top of the notch is flush with the top surface of the lower vertical steel plate, and the net internal dimension of the notch is larger than the cross-sectional dimension of the roof beam. An avoidance groove is opened in the overlapping area of ​​the rectangular annular steel plate II and the lower vertical steel plate corresponding to the notch. Two sets of transverse circular holes are opened in layers on both sides of the steel plate of a single notch. A transverse high-strength tie bolt is inserted through each set of transverse circular holes. The transverse high-strength tie bolt penetrates the concrete at the end of the roof beam to form a two-way shear constraint at the beam end.

5. The reinforcement device for extending column joints in building additions according to claim 4, characterized in that: The thickness of the rectangular annular steel plate II is 10mm to 20mm; the thickness of the lower vertical steel plate is 8mm to 16mm.

6. A reinforcement device for extending column joints in building additions according to claim 1 or 2, characterized in that: The grouting gaps between the upper steel hoop assembly and the newly added column, the lower steel hoop assembly and the original structural column, and the outer walls of the surrounding roof beams are uniformly controlled to be 20mm to 50mm.

7. A reinforcement device for building extension column joints according to claim 1 or 2, characterized in that: All steel components are welded using full welding, with a weld height of not less than 6mm.

8. A construction method for a building addition extension column joint reinforcement device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: All steel components are prefabricated in the factory and anti-corrosion treatment is completed; after arrival on site, the loose layer on the surface of the original beams and columns is cleaned and polished smooth. S2: Make circular holes in the floor slab corresponding to the positions of the vertical bolt holes of the upper and lower steel sleeve components; S3: The new column is formed by casting and molding. After the new column has reached the design strength, the upper steel sleeve assembly is separated along the assembly opening and wrapped around the bottom of the new column from the left and right sides. All assembly gaps of the upper steel sleeve are fully welded and sealed. S4: Separate the lower steel sleeve assembly along the assembly opening, wrap it around the top of the original structural column from the left and right sides, so that all the ends of the roof beams around the perimeter are embedded in the corresponding recessed grooves, install the horizontal high-strength tie bolts through the ends of each beam and tighten them initially; fully weld and seal all splicing positions of the lower steel sleeve assembly. S5: Align the vertical bolt holes of the upper and lower steel sleeve components, insert all the vertical high-strength tie bolts, and tighten them evenly in stages to make the upper and lower steel sleeve components clamp the middle floor slab, so that the floor slab participates in the overall force constraint. S6: Seal the grouting gaps on the sides and bottom of the lower steel sleeve assembly, install grouting nozzles and venting nozzles, and inject high-strength non-shrink grout into the gaps between the upper steel sleeve assembly, the lower steel sleeve assembly and the concrete component. After the grout has cured to the design strength, the reinforcement construction is completed.

9. The construction method of the building addition extension column joint reinforcement device according to claim 8, characterized in that, All steel components are shot blasted to remove rust at grade Sa2.5, and then coated with two coats of epoxy anti-rust primer. The dry film thickness of the primer is ≥60μm. In humid environments, an additional topcoat is applied for corrosion protection.

10. The construction method of the building addition extension column joint reinforcement device according to claim 8 or 9, characterized in that, The high-strength, non-shrink grout has a compressive strength of ≥60MPa after 28 days of standard curing.

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