A construction method for column support replacement and reinforcement using prestressing

Abstract

This application relates to the technical field of building construction, and in particular to a construction method for column replacement and reinforcement using prestressing. Firstly, the method includes the following steps: roughening the surface of the original concrete main beam; adding prestressing tendons; setting a horizontal work line; adding shear reinforcement and tie bars; anchoring reinforcement; calibrating the positioning points; obtaining a prestressed composite beam; roughening the outer wall of the original concrete column; increasing the cross-sectional area of ​​the original concrete column; obtaining a composite column; and removing the central reinforced concrete column. Secondly, the prestressed composite beam is applied in this prestressed column replacement and reinforcement construction method. This method enables structural modification of the original building structure while ensuring the building's safety.

Description

Technical Field

[0001] This application relates to the technical field of building construction, and in particular to a construction method for column underpinning and reinforcement using prestressing. Background Technology

[0002] Buildings and structures are characterized by their large size, high construction and demolition costs, and high resource consumption. Many buildings and structures were designed and built in earlier times. Due to the limitations of the economic conditions, usage requirements, and level of understanding at the time, the structures of these buildings and structures generally have problems such as dense column grids, small spans, and insufficient flexibility in use. In order to adapt to the new functional requirements of large spaces without rebuilding, these structures will need to be modified by demolishing some of the columns.

[0003] In existing technologies, when modifying a building structure by removing columns, the original concrete columns in the middle of the building are often demolished, or the original concrete columns in the middle are demolished and then a new column structure is reconstructed on one side, while the original concrete columns at the corners of the building are retained.

[0004] In application, a temporary support structure is set up around the column to be demolished, such as a temporary support column or jack structure. The original concrete column is demolished and its upper load is transferred to the temporary support structure. Then, space is made to construct the connection between the new structure and the part of the original building structure that has not been demolished. The temporary support structure is then demolished and its upper load is transferred to the newly constructed new structure.

[0005] In reality, in this method of modifying the original building structure by adding a new structure and removing columns, during the multiple load transfer processes—from the upper load of the column to be removed to the temporary support structure, and then from the temporary support structure to the added structure—the remaining portion of the original building structure adjacent to the added structure will inevitably experience accumulated vertical deformation. If this accumulated vertical deformation exceeds a certain limit, it often leads to cracking of the remaining portion of the original building structure above the added structure, thereby affecting the functionality and safety of the remaining portion of the original building structure above the added structure. Summary of the Invention

[0006] In order to modify the original building structure while ensuring the building's safety, this application provides a construction method for column support and reinforcement using prestressing.

[0007] Firstly, this application provides a construction method for column support reinforcement using prestressing, employing the following technical solution:

[0008] A construction method for column underpinning and reinforcement using prestressing includes the following construction steps:

[0009] S1: Roughen the surface of the original concrete main beam;

[0010] S2: Add prestressing tendons along the length of the original concrete main beam. The prestressing tendons are set in a curve and the ends of the prestressing tendons pass through the original concrete column that is close to them.

[0011] S3: Set a horizontal working line, with the ends of the prestressing tendons placed above the horizontal working line and the middle of the prestressing tendons placed below the horizontal working line.

[0012] S4: Add shear bars and tie bars around the original concrete main beam and reinforce the connection points of adjacent steel structures.

[0013] S5: Anchorages are added to the external ends of the original concrete main beam for reinforcement;

[0014] S6: The prestressing and positioning of prestressed steel strands, sheared steel bars, tie bars, and anchorages are calibrated to ensure that the newly added stirrups inside the prestressed composite beam are installed with a reserved installation distance from the column to be dismantled.

[0015] S7: Re-form the exterior of the original concrete main beam, fill it with grout, and cure it to obtain a prestressed composite beam;

[0016] S8: Remove roughening of the original concrete column outer wall;

[0017] S9: Increase the cross-sectional area along the height of the original concrete column;

[0018] S10: A composite column is obtained by re-forming, grouting, and curing the exterior of the original concrete column;

[0019] S11: After the performance of the prestressed composite beams and columns has been inspected and found to be qualified, the central reinforced concrete columns are removed.

[0020] By adopting the above-mentioned technical solution, the surface of the original concrete main beam is roughened, and then prestressed tendons, sheared steel bars, tie bars, and anchorages are added. Finally, grouting is used to fill the entire original floor slab, achieving the effect of reconstructing the original floor slab. This application reconstructs a prestressed composite beam. By applying pre-tension, compressive stress is generated in the compression area of ​​the beam, enhancing the load-bearing capacity of the original floor slab and increasing the beam's bending stiffness and shear strength. Secondly, it can effectively reduce beam cracking and deformation, thereby controlling beam deformation, improving the overall stability and stiffness of the beam, reducing stress concentration when the beam is under load, and thus reducing structural stress and deformation caused by temperature or external force changes, alleviating concrete cracking and corrosion rates, and helping to extend service life. Furthermore, by increasing the tension of the original floor slab, the self-weight of the beam is reduced, which helps to lower the requirements for supports and foundations.

[0021] This application reconstructs a composite column, which further enhances the structural stiffness of the original concrete column, ensuring the structural stability of the column. The addition of additional reinforcement can improve the connection density and tightness of the column, thereby enhancing the durability of the structure.

[0022] Compared with the temporary support structure of existing technology, by reconstructing prestressed composite beams and columns and then removing the reinforced concrete columns in the middle of the building, the prestressed composite beams and columns can be integrated with the original structure of the building, improving structural stability, avoiding repeated disassembly by construction workers, shortening the construction period, saving construction costs, and reducing the possibility of collapse caused by assembly errors between the original structure and the temporary support structure. This achieves the goal of structural modification of the original building structure while ensuring the safety of building use.

[0023] Preferably, the original concrete main beam is extended to one side of the horizontal work line. In the S4 construction step, prestressed corrugated pipes are perforated around the bottom of the original concrete main beam. Multiple original concrete secondary beams are set on the original concrete main beam. Then, beam armholes are added to the bottom of the original concrete secondary beams so that the width of the beam armholes is consistent with the width of the original concrete secondary beams.

[0024] By adopting the above technical solution, this application can fix the prestressed steel strands by adding a beam armhole at the bottom of the original concrete secondary beam. Compared with the prior art, the setting of the beam armhole can increase the protective layer thickness of the prestressed steel strands, thereby enhancing the installation stability of the prestressed steel strands.

[0025] Preferably, in the construction step S5, the anchor includes a fixed end and a tensioning end. After the anchor is installed and the prestressed tendons are tensioned, concrete is poured around the original floor slab near the anchor.

[0026] By adopting the above technical solution, the anchor is divided into a fixed end and a tensioning end, which can provide stable support and tension transmission during construction. The fixed end is located at a fixed position on the structure and is used to fix one end of the component, enabling it to withstand external loads and remain stable. The tensioning end is used to apply tension, stretching the component to the prestressed state required by the design. In prestressed concrete structures, applying prestress by tensioning prestressed steel strands can improve the structure's load-bearing capacity and crack resistance.

[0027] Preferably, in the construction step S5, there are at least two anchorages at one end of the original floor slab, the two anchorages are symmetrically arranged along the centerline of the beam, and the anchorages are assembled with the end of the prestressed corrugated pipe.

[0028] By adopting the above technical solution, the anchors are symmetrically distributed in an even number at the ends of the original floor slab, which allows the prestressed corrugated pipes to be firmly anchored in the concrete structure. Furthermore, the prestressed corrugated pipes are more evenly distributed on the outside of the original floor slab, providing better load-bearing capacity for the original floor slab, thereby reducing structural deformation and enhancing the durability of the structure.

[0029] Preferably, in the construction step S9, the additional reinforcement includes a first vertical reinforcement, a second vertical reinforcement, a third vertical reinforcement, and a fourth vertical reinforcement. The first vertical reinforcement serves as the base, and the second, third, and fourth vertical reinforcements are simultaneously assembled with the first vertical reinforcement. The outline width of the second, third, and fourth vertical reinforcements gradually decreases.

[0030] By adopting the above technical solution, the first, second, third, and fourth vertical bars are all used to increase the outer contour of the original concrete column section, which can increase the cross-sectional area of ​​the original concrete column, thereby increasing the load-bearing capacity and seismic performance of the composite column, helping to reduce the displacement of the composite column, reduce the deflection and deformation of the column, and keep the composite column in a stable state.

[0031] Preferably, in the construction step S9, a first column armhole is formed between the first vertical bar and its adjacent outer edge, and a second column armhole is formed between the fourth vertical bar and its adjacent outer edge, ensuring that the width of the first column armhole is smaller than the width of the second column armhole.

[0032] By adopting the above technical solution, firstly, the original floor slab will transfer the upper load to the column, while the second column axle with a larger width can bear more load, so that the load can be smoothly transferred to the composite column; secondly, it enhances the structural strength and rigidity of the composite column, which helps to resist bending.

[0033] Preferably, in the construction step S9, when adding the first stirrup, the first stirrup is anchored into the original concrete main beam when it encounters it, or it is bent in the opposite direction of the original concrete column when it encounters the original floor slab, and then anchored into the prestressed composite beam.

[0034] By adopting the above technical solutions, in the first case, it can be ensured that the first stirrup has good connection stability with the original concrete main beam, thereby enhancing the overall structural stability and load-bearing capacity; in the second case, it can be ensured that the first stirrup has good connection stability with the original floor slab, while maintaining the stable state between the composite column and the prestressed composite beam, making the connection between the two more solid and reliable.

[0035] Preferably, in the construction step S9, shear reinforcement is added in both the first column axle and the second column axle, and the shear reinforcement in the second column axle is densified to form a shear reinforcement densified zone.

[0036] By adopting the above technical solution, the shear reinforcement has good shear resistance and shear bearing capacity. Adding shear reinforcement in both the first and second column axles can enhance the bond between it and the concrete, forming a strong tensile support system in this area to withstand the shear force in the concrete and prevent the concrete in the first and second column axles from being destroyed by shear force, thereby achieving the purpose of enhancing the shear resistance of the composite column.

[0037] Secondly, the prestressed composite beam provided in this application is applied in a construction method for column support reinforcement using prestressing, and adopts the following technical solution:

[0038] The prestressed composite beam is used in a construction method for column support and reinforcement using prestressing. It includes prestressed tendons, a first pouring layer, prestressed tendons bundled together to obtain prestressed steel strands, prestressed steel strands placed inside prestressed corrugated pipes, so that the prestressed tendons are arranged in a curve along the length of the original floor slab, and the first pouring layer completely covers the outer surface of the original floor slab equipped with prestressed tendons.

[0039] By adopting the above technical solution, this application reconstructs a prestressed composite beam. By applying a pre-tension force, compressive stress is generated in the compression area of ​​the beam, which enhances the load-bearing capacity of the original floor slab and the bending stiffness and shear strength of the beam. When the reinforced concrete column in the middle of the building is removed, the prestressed composite beam has sufficient capacity to disperse the force in that part, ensuring the safety of the building.

[0040] Preferably, it also includes anchorages and a second pouring layer. The anchorages are disposed outside the prestressed tendons that pass through the composite column, and the anchorages are reinforced to the original transfer beam through the second pouring layer.

[0041] By adopting the above technical solution, the combined action of the anchor and the second pouring layer can provide a more robust connection, which can firmly anchor the prestressing tendons in the concrete structure, thereby increasing the connection strength between the prestressing tendons and the composite column and reducing the loosening or detachment between the prestressing tendons and the concrete.

[0042] In summary, this application includes at least one of the following beneficial technical effects:

[0043] 1. This application reconstructs a prestressed composite beam. By applying pre-tension, compressive stress is generated in the compression area of ​​the beam, which enhances the load-bearing capacity of the original floor slab and strengthens the beam's bending stiffness and shear strength. Secondly, it can effectively reduce beam cracking and deformation, thereby controlling beam deformation and improving the overall stability and stiffness of the beam. Furthermore, by increasing the tension of the original floor slab, it reduces the beam's self-weight, which helps to lower the requirements for supports and foundations.

[0044] 2. This application reconstructs a composite column, which further enhances the structural rigidity of the original concrete column, ensuring the structural stability of the column. The addition of additional reinforcement can improve the connection density and tightness of the column, thereby enhancing the durability of the structure.

[0045] 3. Compared with the temporary support structure of the existing technology, by reconstructing the prestressed composite beams and columns and then removing the reinforced concrete columns in the middle of the building, the prestressed composite beams and columns can be integrated with the original structure of the building, which improves the structural stability, avoids repeated disassembly by construction workers, shortens the construction period, saves construction costs, and can reduce the collapse caused by assembly errors between the original structure and the temporary support structure. It achieves the goal of structural modification of the original building structure while ensuring the safety of building use. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0047] Figure 2 This is a schematic diagram of the prestressed composite beam in the embodiments of this application.

[0048] Figure 3 This is a cross-sectional schematic diagram of the middle part of the prestressed composite beam in the embodiment of this application.

[0049] Figure 4 This is a schematic cross-sectional view of the end of the prestressed composite beam in an embodiment of this application.

[0050] Figure 5 This is a schematic diagram of the installation of the anchor tensioning end in an embodiment of this application.

[0051] Figure 6 This is a schematic diagram of the installation of the anchor fixing end in an embodiment of this application.

[0052] Figure 7 This is a schematic diagram showing the fit between the fixed end of the anchor and the prestressed steel strand in an embodiment of this application.

[0053] Figure 8 This is a schematic diagram of the structure of the combined column in the embodiments of this application.

[0054] Figure 9 yes Figure 8 A cross-sectional view of section 1-1.

[0055] Figure 10 yes Figure 8 Schematic diagram of cross section 2-2.

[0056] Figure 11 This is a partial enlarged view of the bottom end of the combined column in an embodiment of this application.

[0057] Explanation of reference numerals in the attached drawings: 1. Prestressed composite beam; 11. Original floor slab; 12. Original concrete main beam; 121. Roughened surface; 122. Original concrete secondary beam; 13. First pouring layer; 14. Second pouring layer; 2. Newly added stirrups; 3. Composite column; 31. Original concrete column; 32. Additional reinforcement; 321. First vertical reinforcement; 322. Second vertical reinforcement; 323. Third vertical reinforcement; 324. Fourth vertical reinforcement; 325. First stirrup; 326. Second stirrup; 327. Third stirrup; 328. First column axle; 329. Second... Column axle; 3210, shear reinforcement; 33, bottom reinforcement; 34, epoxy mortar; 4, horizontal work line; 51, shear reinforcement; 52, tie bar; 53, concrete beam stirrups; 6, reinforced concrete column; 71, prestressed steel strand; 72, beam axle; 8, anchorage; 81, fixed end; 811, prestressed tendon; 812, spiral reinforcement; 813, anchor plate; 814, extrusion sleeve; 82, tensioning end; 821, wedge anchorage; 822, elastic element; 823, connector; 9, original transfer beam; 10, newly added stirrups. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1-11 This application will be described in further detail.

[0059] In the first aspect, embodiments of this application disclose a construction method for column underpinning and reinforcement using prestressing.

[0060] Reference Figure 1 and Figure 2 A construction method for column underpinning and reinforcement using prestressing includes the following construction steps:

[0061] S1: Roughen the surface of the original concrete main beam 12.

[0062] S2: Add prestressed tendons 811 along the length of the original concrete main beam 12. The prestressed tendons 811 are set in a curve. The ends of the prestressed tendons 811 pass through the original concrete column 31 that is close to them. Bundle multiple prestressed tendons 811 into a bundle to obtain prestressed steel strands 71.

[0063] S3: Set a horizontal working line 4, with the end of the prestressed tendon 811 positioned above the horizontal working line 4 and the middle part of the prestressed tendon 811 positioned below the horizontal working line 4.

[0064] S4: Reference Figure 2 and Figure 3 Shear bars 51 and tie bars 52 are added around the original concrete main beam 12, and the connection points of adjacent steel structures are reinforced.

[0065] The original concrete main beam 12 is extended to one side of the horizontal work line 4. In the construction step S4, prestressed corrugated pipes are perforated around the bottom of the original concrete main beam 12. Multiple original concrete secondary beams 122 are set on the original concrete main beam 12. The multiple original concrete secondary beams 122 are evenly arranged. Then, beam armholes 72 are added to the bottom of the original concrete secondary beams 122, so that the width of the beam armholes 72 is consistent with the width of the original concrete secondary beams 122.

[0066] This application adds a beam armhole 72 to the bottom of the original concrete secondary beam 122, which can be used to fix the prestressed steel strand 71. Compared with the prior art, the setting of the beam armhole 72 can increase the protective layer thickness of the prestressed steel strand 71, thereby enhancing the installation stability of the prestressed steel strand 71.

[0067] Among them, the newly added stirrups 10 are rectangular stirrup structures. Each original concrete main beam 12 is provided with several newly added stirrups 10. The multiple newly added stirrups 10 are evenly arranged along the length of the original concrete main beam 12. Furthermore, the top of the newly added stirrups 10 is embedded in the original concrete main beam 12, so as to further increase the overall shear resistance of the prestressed composite beam 1 and help the main reinforcement and the compression zone concrete to work together.

[0068] A roughened surface 121 is added to the outer wall of the original concrete main beam 12. The roughened surface 121 is used to increase the adhesion of the original concrete main beam 12 and improve its anti-slip properties, so as to ensure the subsequent processing of the enlarged cross section of the original concrete main beam 12.

[0069] Multiple new stirrups 2 are added to the inner side of the new stirrup 10. The multiple new stirrups 2 are distributed at equal intervals along the perimeter of the new stirrup 10, and the new stirrups 2 are reinforced with the new stirrup 10 by welding.

[0070] S5: Anchorage 8 is added to the outside of the end of the original concrete main beam 12 for reinforcement.

[0071] Reference Figure 1 and Figure 6 The prestressed steel strand 71 is inserted into the prestressed corrugated pipe. There are at least two anchors 8 at one end of the original floor slab 11. The two anchors 8 are symmetrically arranged along the center line of the beam. The anchors 8 are assembled with the end of the prestressed corrugated pipe. In this application, after the anchors 8 are added and the prestressed tendons 811 are tensioned, concrete is poured around the original floor slab 11 near the anchors 8.

[0072] Anchors 8 are symmetrically distributed in even numbers at the ends of the original concrete main beam 12, ensuring that the prestressed steel strands 71 ​​are firmly anchored in the concrete structure. (Refer to...) Figure 6 and Figure 7 The anchor 8 includes a fixed end 81 and a tensioning end 82.

[0073] S6: The prestressing and positioning of the prestressed steel strands 71, sheared steel bars 51, tie bars 52, and anchorages 8 are calibrated to ensure that the newly added stirrups 10 inside the prestressed composite beam 1 are installed with a reserved distance from the column to be dismantled.

[0074] S7: Re-formwork, grout filling, and curing are carried out on the outside of the original concrete main beam 12 to obtain the prestressed composite beam 1.

[0075] In the construction process of the prestressed composite beam 1 of this application, the construction steps of the middle part of the beam and the beam ends are similar. The difference between the two lies in the arrangement position of the prestressed steel strands 71 ​​and the degree of bending of the prestressed tendons 811.

[0076] When adding shear reinforcement 51, tie bars 52, and prestressed steel strands 71, the concrete beam stirrups 53 enclose the entire original concrete main beam 12, placing the original concrete main beam 12 in the middle of the concrete beam stirrups 53. In this application, the prestressed tendons 811 are always distributed inside the prestressed corrugated pipe, so that the extension direction of the prestressed tendons 811 is consistent with the prestressed composite beam 1. The prestressed tendons 811 in the middle area of ​​the prestressed composite beam 1 are placed below the horizontal working line 4, and the prestressed tendons 811 in the two end areas of the prestressed composite beam 1 are placed above the horizontal working line 4, so that the prestressed tendons 811 present an overall wavy or S-shaped structure.

[0077] Several tie bars 52 are provided, which are inclined downward from the bottom end of the original concrete main beam 12 to the central axis of the original concrete main beam 12. The top end of the tie bar 52 is inserted into the roughened surface 121, and its bottom end is tied to the newly added web bar 2 that is close to it, so as to fix the three together. One end of the shear bar 51 is connected to the original concrete main beam 12, so that the extension direction of the shear bar 51 is perpendicular to the length direction of the concrete beam stirrup 53, which helps to enhance the bending stiffness and shear strength of the beam.

[0078] In this application, when the distance between the edge of the composite column 3 and the prestressed composite beam 1 is less than or equal to 150 mm, the beam top reinforcement bypasses the column and passes through the vertical beam, while the beam bottom reinforcement bypasses the column edge; when the distance between the edge of the composite column 3 and the prestressed composite beam 1 is greater than 150 mm, at least one rebar each of the beam top reinforcement and the beam bottom reinforcement of the prestressed composite beam 1 has an opening through the column. Furthermore, refer to... Figure 3 and Figure 4 The prestressed steel strands 71 ​​in the middle area of ​​the prestressed composite beam 1 are placed on the bottom left and right sides of the original concrete main beam 12, and the prestressed steel strands 71 ​​at both ends of the prestressed composite beam 1 are placed on the top left and right sides of the original concrete main beam 12. Whether it is a steel bar or a prestressed steel strand 71, it passes through the column through the opening, and its end is fixed to the composite column 3 by the anchor 8, and the anchorage length requirement is met. The perforation position is filled with grout.

[0079] Reference Figure 5 Specifically, when the fixed end 81 of the anchor 8 is assembled with the prestressed corrugated pipe, several prestressed tendons 811 pass through the middle of the prestressed corrugated pipe, and a spiral tendon 812 is added to the end of the prestressed tendon 811. A single-hole anchor plate 813 and a compression sleeve 814 are added to the end of the spiral tendon 812 away from the prestressed corrugated pipe, and the single-hole anchor plate 813 and the compression sleeve 814 on the spiral tendon 812 are completely embedded in the combined column 3, thereby realizing the assembly between the prestressed steel strand 71 and the combined column 3.

[0080] Reference Figure 6 and Figure 7 More specifically, when the tensioning end 82 of the anchor is assembled with the prestressed corrugated pipe, several prestressed tendons 811 are placed inside the prestressed corrugated pipe, and the ends of the prestressed steel strands 71 ​​are provided with clamp anchors 821 and elastic elements 822. The elastic elements 822 are sleeved on the outer wall of the prestressed corrugated pipe, and the prestressed steel strands 71 ​​are assembled with the clamp anchors 821 through connectors 823, so that the tensioning end 82 of the anchor is fixed to the combined column 3.

[0081] S8: Remove the roughness of the outer wall of the original concrete column 31.

[0082] S9: Increase the cross-sectional area along the height direction of the original concrete column 31.

[0083] Reference Figure 8 In the construction step S9, the additional reinforcement 32 includes a first vertical reinforcement 321, a second vertical reinforcement 322, a third vertical reinforcement 323, a fourth vertical reinforcement 324, a first stirrup 325, a second stirrup 326, and a third stirrup 327. The first vertical reinforcement 321, the second vertical reinforcement 322, the third vertical reinforcement 323, and the fourth vertical reinforcement 324 are all used to increase the outer contour of the original concrete column 31 section. Furthermore, with the first vertical reinforcement 321 as the foundation, the second vertical reinforcement 322, the third vertical reinforcement 323, and the fourth vertical reinforcement 324 are simultaneously assembled with the first vertical reinforcement 321. In this application, the contour width of the second vertical reinforcement 322, the third vertical reinforcement 323, and the fourth vertical reinforcement 324 gradually decreases.

[0084] The first stirrup 325 is distributed between the second vertical bar 322 and its adjacent outer edge. The second stirrup 326 is distributed in the space formed by the second vertical bar 322 and the third vertical bar 323, and in the space formed by the third vertical bar 323 and the fourth vertical bar 324. This application does not limit the number of various steel reinforcement structures of the additional bars 32. The number and spatial layout can be determined according to the actual situation, but it is required that multiple bars of the same type are parallel and equidistantly distributed to ensure that the original concrete column 31 can be uniformly stressed.

[0085] In this application, a first pillar armpit 328 is formed between the first vertical rib 321 and its adjacent outer edge, and a second pillar armpit 329 is formed between the fourth vertical rib 324 and its adjacent outer edge, ensuring that the width of the first pillar armpit 328 is smaller than the width of the second pillar armpit 329.

[0086] Reference Figure 8 and Figure 9 In this application, when the first stirrup 325 is added, it is either anchored into the original concrete main beam 12 when it encounters the original floor slab 11, or bent in the opposite direction of the original concrete column 31 before being anchored into the prestressed composite beam 1 when it encounters the original floor slab 11. The first case can ensure good connection stability between the first stirrup 325 and the original concrete main beam 12, enhancing the overall structural stability and load-bearing capacity. The second case can ensure good connection stability between the first stirrup 325 and the original floor slab 11, while maintaining the stable state between the composite column 3 and the prestressed composite beam 1, making the connection between the two more firm and reliable.

[0087] Reference Figure 9 and Figure 10 Meanwhile, shear reinforcement 3210 is added in both the first column axle 328 and the second column axle 329. The shear reinforcement 3210 in the second column axle 329 is densified to form a shear reinforcement 3210 densified zone. The shear reinforcement 3210 has good shear resistance and shear bearing capacity. By adding shear reinforcement 3210, the bond between it and the concrete can be strengthened, so that the area forms a strong tensile support system to withstand the shear force in the concrete and prevent the concrete at the first column axle 328 and the second column axle 329 from being destroyed by shear force, thereby achieving the purpose of enhancing the shear resistance of the composite column 3.

[0088] S10: After re-forming, grouting, and curing the exterior of the original concrete column 31, a composite column 3 is obtained.

[0089] S11: After the performance of the prestressed composite beam 1 and composite column 3 after processing is qualified, the middle reinforced concrete column 6 is removed.

[0090] S12: After removing the reinforced concrete column 6, expose the bottom reinforcement bars, then add new reinforcing bottom reinforcement bars 33 and weld them to the original bottom reinforcement bars, and finally seal the joint with epoxy mortar 34.

[0091] This application reconstructs a prestressed composite beam 1. By applying pre-tension, compressive stress is generated in the compression area of ​​the beam, enhancing the load-bearing capacity of the original floor slab 11 and increasing the beam's bending stiffness and shear strength. Secondly, it can effectively reduce beam cracking and deformation, thereby controlling beam deformation, improving the overall stability and stiffness of the beam, reducing stress concentration when the beam is under load, and thus reducing structural stress and deformation caused by temperature or external force changes, alleviating concrete cracking and corrosion, and helping to extend service life. Furthermore, by increasing the tension of the original floor slab 11, the self-weight of the beam is reduced, which helps to lower the requirements for supports and foundations.

[0092] This application reconstructs the composite column 3, further enhancing the structural stiffness of the original concrete column 31 to ensure the structural stability of the column. The addition of additional reinforcement 32 can improve the connection density and tightness of the column, thereby enhancing the durability of the structure.

[0093] Compared with the temporary support structure of the existing technology, by reconstructing the prestressed composite beam 1 and composite column 3 and then removing the reinforced concrete column 6 in the middle of the building, the prestressed composite beam 1 and composite column 3 can be integrated with the original structure of the building, which improves the structural stability, avoids repeated disassembly by construction workers, shortens the construction period, saves construction costs, and can reduce the collapse caused by assembly errors between the original structure and the temporary support structure. It achieves the goal of structural modification of the original building structure while ensuring the safety of building use.

[0094] Secondly, the embodiments of this application disclose prestressed composite beams, which are applied in a construction method for column support reinforcement using prestressing.

[0095] Reference Figure 1 and Figure 2 The prestressed composite beam 1 includes prestressed tendons 811 and a first pouring layer 13. The prestressed tendons 811 are bundled together to obtain prestressed steel strands 71. The prestressed steel strands 71 ​​are placed inside the prestressed corrugated pipe so that the prestressed tendons 811 are arranged in a curve along the length of the original floor slab 11. The first pouring layer 13 completely covers the outer surface of the original floor slab 11 equipped with prestressed tendons 811.

[0096] The prestressed composite beam 1 also includes anchorages 8 and a second pouring layer 14. The anchorages 8 are set outside the prestressed tendons 811 passing through the composite column 3. The anchorages 8 are reinforced with the original transfer beam 9 through the second pouring layer 14, which can provide a more robust connection, increase the connection strength between the prestressed tendons 811 and the composite column 3, and reduce the loosening or falling off between the prestressed tendons 811 and the concrete.

[0097] This application reconstructs a prestressed composite beam 1. By applying a pre-tension force, compressive stress is generated in the compression area of ​​the beam, which enhances the load-bearing capacity of the original floor slab 11, and enhances the bending stiffness and shear strength of the beam. When the reinforced concrete column 6 in the middle of the building is removed, the prestressed composite beam 1 has sufficient capacity to disperse the force in that part, ensuring the safety of the building.

[0098] The above are all preferred embodiments of this application. These embodiments are merely explanations of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A construction method for column underpinning and reinforcement using prestressing, characterized in that, The construction steps include the following: S1: Roughen the surface of the original concrete main beam (12); S2: Add prestressed tendons (811) along the length of the original concrete main beam (12). The prestressed tendons (811) are set in a curve and the ends of the prestressed tendons (811) pass through the original concrete column (31) that is close to them. S3: Set a horizontal working line (4), with the end of the prestressed tendon (811) placed above the horizontal working line (4) and the middle part of the prestressed tendon (811) placed below the horizontal working line (4); S4: Shear bars (51) and tie bars (52) are added around the original concrete main beam (12), and the connection points of adjacent steel structures are reinforced. S5: Anchorages (8) are added to the outside of the end of the original concrete main beam (12) for reinforcement; S6: The prestress and fixed position of the prestressed steel strands (71), sheared steel bars (51), tie bars (52), and anchorages (8) are calibrated to ensure that the newly added stirrups (10) inside the prestressed composite beam (1) and the column to be dismantled are reserved for installation distance. S7: Re-form the outside of the original concrete main beam (12), fill it with grout, and cure it to obtain a prestressed composite beam (1); S8: Remove the roughness of the outer wall of the original concrete column (31); S9: Increase the cross-sectional area along the height direction of the original concrete column (31); S10: After re-forming, grouting, and curing the exterior of the original concrete column (31), a composite column (3) is obtained; S11: After the performance of the prestressed composite beam (1) and composite column (3) after processing is qualified, the middle reinforced concrete column (6) is removed; In the construction step of S5, the anchor (8) includes a fixed end (81) and a tensioning end (82). After the anchor (8) is added and the prestressed tendon (811) is tensioned, concrete is poured around the original floor slab (11) near the anchor (8). When the fixed end (81) of the anchor (8) is assembled with the prestressed corrugated pipe, several prestressed tendons (811) pass through the middle of the prestressed corrugated pipe. Spiral tendons (812) are added to the ends of the prestressed tendons (811). A single-hole anchor plate (813) and a compression sleeve (814) are added to the end of the spiral tendon (812) away from the prestressed corrugated pipe. The single-hole anchor plate (813) and the compression sleeve (814) on the spiral tendon (812) are completely embedded in the composite column (3) to realize the assembly between the prestressed steel strand (71) and the composite column (3). When the tensioning end (82) of the anchor is assembled with the prestressed corrugated pipe, several prestressed tendons (811) are placed inside the prestressed corrugated pipe. The end of the prestressed steel strand (71) is provided with a wedge anchor (821) and an elastic element (822). The elastic element (822) is sleeved on the outer wall of the prestressed corrugated pipe. The prestressed steel strand (71) is assembled with the wedge anchor (821) through the connector (823) so that the tensioning end (82) of the anchor is fixed to the combined column (3). In the construction step S9, the additional reinforcement (32) includes a first vertical reinforcement (321), a second vertical reinforcement (322), a third vertical reinforcement (323), and a fourth vertical reinforcement (324). The first vertical reinforcement (321) serves as the foundation, and the second vertical reinforcement (322), the third vertical reinforcement (323), and the fourth vertical reinforcement (324) are simultaneously assembled with the first vertical reinforcement (321). The outline width of the second vertical reinforcement (322), the third vertical reinforcement (323), and the fourth vertical reinforcement (324) gradually decreases. In the construction step S9, a first column armhole (328) is formed between the first vertical bar (321) and its adjacent outer edge, and a second column armhole (329) is formed between the fourth vertical bar (324) and its adjacent outer edge, ensuring that the width of the first column armhole (328) is smaller than the width of the second column armhole (329). In the construction step S9, shear reinforcement (3210) is added in both the first column axle (328) and the second column axle (329), and the shear reinforcement (3210) in the second column axle (329) is densified to form a densified shear reinforcement (3210) zone.

2. The construction method for column support reinforcement using prestressing according to claim 1, characterized in that, The original concrete main beam (12) is extended to one side of the horizontal working line (4). In the construction step of S4, the bottom of the original concrete main beam (12) is perforated with prestressed corrugated pipes. Multiple original concrete secondary beams (122) are set on the original concrete main beam (12). Then, beam armholes (72) are added to the bottom of the original concrete secondary beams (122) so that the width of the beam armholes (72) is consistent with the width of the original concrete secondary beams (122).

3. The construction method for column support reinforcement using prestressing according to claim 2, characterized in that, In the construction step S5, there are at least two anchors (8) at one end of the original floor slab (11). The two anchors (8) are symmetrically arranged along the center line of the beam and are assembled with the end of the prestressed corrugated pipe.

4. The construction method for column support reinforcement using prestressing according to claim 1, characterized in that, In the construction step of S9, when the first stirrup (325) is installed, the first stirrup (325) is anchored into the original concrete main beam (12) when it encounters the original floor slab (11), or it is first bent in the opposite direction of the original concrete column (31) and then anchored into the prestressed composite beam (1).

5. A construction method for column support reinforcement using prestressing according to any one of claims 1-4, characterized in that, The prestressed composite beam is applied to a prestressed composite beam, which includes prestressed tendons (811) and a first pouring layer (13). The prestressed tendons (811) are bundled together to obtain prestressed steel strands (71). The prestressed steel strands (71) are placed inside a prestressed corrugated pipe so that the prestressed tendons (811) are arranged in a curve along the length of the original floor slab (11). The first pouring layer (13) completely covers the outer surface of the original floor slab (11) equipped with prestressed tendons (811).

6. A construction method for column support reinforcement using prestressing according to claim 5, characterized in that, It also includes an anchor (8) and a second pouring layer (14). The anchor (8) is located outside the prestressed tendon (811) passing through the composite column (3). The anchor (8) is reinforced with the original transfer beam (9) through the second pouring layer (14).

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