Construction method for supporting beam and pulling column

Abstract

The invention relates to a construction method for supporting beams and pulling columns, and relates to the technical field of supporting beams and pulling columns. The method comprises the steps that S1, a demolition area is selected, wherein the number of columns in the area needing to be demolited is determined on the basis of column positions and peripheral structure conditions in an originally-designed building body 1; s2, the whole structure is dismantled; S21, temporary supporting is conducted, specifically, a door type steel support is installed on the periphery of a column needing to be dismantled, a closed stress ring is formed, and a hydraulic synchronous jacking system is arranged on the top of the column; and S22, peripheral column pre-reinforcement is conducted, specifically, a section expanding method is adopted for peripheral columns, a peripheral supporting column structure of a construction position is reinforced, and according to the design requirement, original columns and peripheral structures are completely dismantled in sequence in the construction sequence. Instead, the root area of the original column is converted into a rigid node of the beam, so that the original four-column load can be transferred to a peripheral column group.

Description

Technical Field

[0001] The present application relates to the technical field of supporting beams and pulling out columns, and in particular to a construction method for supporting beams and pulling out columns. Background Art

[0002] The joist column removal is a general term for the joist column removal, joist wall removal and joist column removal. It is a comprehensive technology for removing, replacing, lengthening columns or removing walls without or with minimal removal of the superstructure. It includes related structural reinforcement technology, superstructure lifting technology and column breaking technology. It is mainly used for the renovation of old houses and old factories that require changes in floor plan and increase in usable space due to changes in usage functions and production process updates. It is also often used for the renovation of comprehensive buildings with additional halls. In the prior art, the related technology of beam-lifting and column-lifting can refer to the Chinese patent with publication number CN110259184A, which discloses a column-lifting construction method based on a beam-lifting and column-lifting combined support jacking system, including that before the column is pulled out, a column-lifting method is set with an embracing column support above and below the beam-lifting height position, as a support for the later steel support and jack steel support system, a steel support composed of 4 round steel pipes is set and a jack jacking force is applied to unload and remove the upper load of the column; after jacking and unloading, the column section between the embracing column support is first removed; after the beam is constructed, the jack can be unloaded, the steel support system can be removed, and finally the frame column is completely pulled out. This method has the characteristics of convenient construction, less consumables and labor, low noise pollution, high safety performance, etc. The steel support system can be repeatedly recycled, while improving construction efficiency and construction quality, reducing costs, which is conducive to the survival of enterprises in competition. It is suitable for the construction of beam-lifting and column-lifting of reinforced concrete structures in construction projects after the use of new beams to pull out the lower part of the beam.

[0003] The inventor discovered the following problems in the prior art during the implementation of this application: The existing technology has great safety hazards during the construction process, especially in the process of local reinforcement and column displacement, which is prone to structural instability or uneven load distribution. In addition, the long construction period and high cost are also the main defects of the existing technology, especially in large-scale construction projects, these problems are more prominent, and when the building is supported by beams and columns, it is often necessary to remove all the columns in an area during construction due to the structural factors of the original design. However, due to the problem of its own building space, it is impossible to construct new columns around it. Therefore, it is often a second choice to reduce the removal of columns to maintain the basic stability of the building after construction. Summary of the invention

[0004] The purpose of this application is to provide a construction method for supporting beams and pulling out columns.

[0005] The present application provides a construction method for supporting beams and pulling out columns, which adopts the following technical solution: A construction method for supporting beams and pulling out columns comprises the following steps: S1. Demolition area selection: Determine the number of columns in the area to be demolished based on the column positions in the original design building and the surrounding structural conditions; S2. Overall structural demolition: According to design requirements, the original columns and surrounding structures are completely demolished in sequence according to the construction sequence; S21, temporary support: install portal steel supports around the columns to be removed to form a closed stress ring, and set up a hydraulic synchronous jacking system on the top; S22, Pre-reinforcement of peripheral columns: The peripheral columns are reinforced by enlarging the section and strengthening the peripheral support column structure; S3. Treatment of pre-rooting of columns: According to the construction design, the original designed columns are removed in sequence, and the column roots retained after the construction of the original designed columns are used as reserved points to extend and reinforce the surrounding columns; S31. Demolition in stages: According to the construction design, demolition shall be carried out column by column in the order of diagonal lines of the construction surface. After each demolition, the deformation degree of the surrounding area of ​​the construction shall be monitored for 48 hours; S32, root section treatment: roughen the reserved column roots, expose the column reinforcement and weld the extension reinforcement, and drill holes to implant shear bolts; S4, Wrapping reinforcement construction: The root area of ​​the original column is converted into a rigid node of the beam; only the root of the original column is retained in the wrapping area, and the upper column is completely removed to form a column-free space. The load is transferred to the adjacent structure through the wrapping area; S41, steel cage binding: vertical main reinforcement, welded with the original column reinforcement 7, and connected with the annular stirrups with the vertical main reinforcement; S42, Formwork support: Use standard steel formwork, apply release agent on the inside, add water stop strips at the joints, and install grouting holes and vent holes; S42, concrete pouring: C60 self-compacting micro-expansive concrete is used for pouring, and it is poured in sections from the bottom to the top, and the inserted vibrator and the vibrator attached to the formwork are used for joint vibrating; S5. Load transfer and system conversion: During the construction process, load transfer is carried out in stages according to the construction progress, and the supporting structure is removed; S51, Gradual unloading: Use hydraulic jacks to unload in 4 stages, with an interval of 6 hours between each stage, and simultaneously monitor the strain and deflection of the wrapping area; S52, support removal: after the construction is completed, remove the circumferential support and keep the four corner supports until the concrete strength reaches 100%, start cutting the temporary support and use a grinding wheel saw to cut it off section by section; S6. Inspection and acceptance: Carry out crack inspection in the package area, detection of settlement difference of surrounding columns and use ultrasonic detection to detect the density of concrete in the package area; In step S1: Use a 3D scanner to build a BIM model, and mark the positions of the four columns and the adjacent reinforcement structures. Use the BIM model to determine the scope of the package area, and verify the bearing capacity of the surrounding columns. The bearing capacity of the surrounding columns is calculated by the following formula: Stability factor, f c : Axial compressive strength of concrete, A c : Concrete cross-sectional area, f y ′ : Compressive strength of steel bars, A ′ s : Compression steel area Accept the bearing capacity of the surrounding columns. When the bearing capacity does not meet the construction standards, carbon limit cloth will be used for reinforcement.

[0006] By adopting the above technical solution, the original four-column load can be transferred to the surrounding column group by wrapping the original column roots and connecting them into an integral beam system. Only a few columns in the construction area are demolished, and columns are added at other new positions. The surrounding structure of the demolished columns is structurally reinforced. The final approach of the project is to demolish all the structures in this area, together with the displaced columns, and rebuild the new reinforced area in this area as a whole. Therefore, during the construction process, after the columns of the construction itself are demolished, the columns are no longer rebuilt elsewhere. Instead, the root area of ​​the original column is converted into a rigid node of the beam. Only the root of the original column is retained in the wrapping area, and the upper column is completely demolished to form a column-free space. The load is transmitted to the adjacent structure through the wrapping area, rather than relying on the vertical support of the original column position, so as to realize the demolition of the columns at the construction site and reduce the stress change problem at the corresponding nodes when the columns are demolished.

[0007] In step S2: according to the design requirements, the original columns and surrounding structures are completely dismantled in sequence along the construction sequence, and portal steel supports are installed around the columns to be dismantled to form a closed load ring, and a hydraulic synchronous jacking system is set on the top with an accuracy of ±1mm, which is pre-loaded to 150% of the design load; the peripheral columns are subjected to the expanded section method, the surface is roughened and reinforced, and C40 concrete is cast in a formwork with a thickness of ≥100mm to reinforce the peripheral support column structure of the construction site.

[0008] In step S3: the originally designed columns are dismantled in sequence, and the column roots retained after the construction of the originally designed columns are used as reserved points to extend to and reinforce the surrounding columns; according to the construction design, the columns are dismantled one by one in the order of the diagonal line of the construction surface, the first column is dismantled, and the second column is dismantled after each column, forming a dismantling layout of 1, 3, 2, and 4, and the roots of the dismantled columns are retained by 300mm to reserve construction positions for subsequent construction of the wrapped area, and each time the columns are dismantled, the construction is suspended for 48 hours to monitor the degree of deformation around the construction site, and the retained column roots are roughened with a concave-convex difference of ≥6mm, and the column reinforcement is exposed and welded to extend the reinforcement, and shear bolts are drilled and implanted.

[0009] By adopting the above technical solution, when dismantling the original main body, a diamond wire saw is used to separate it in stages, and the cutting height of the column is controlled. Only the column structure is dismantled, but 300mm of the root is retained as the junction between the new and old structures. The cutting line is located 500mm above the bottom elevation of the beam to ensure that the wrapped area does not encroach on the usable space. After dismantling the column, the column reinforcement of the original column is exposed, and long reinforcement is welded based on the column reinforcement, where the diameter of the long reinforcement is 25mm.

[0010] In step S4: the root area of ​​the original column is converted into a rigid node of the beam, and the upper column is completely removed to form a column-free space; the load is transferred to the adjacent structure through the wrapping area, and only the root of the original column is retained in the wrapping area, and the steel cage is tied with the root of the original column.

[0011] In step S4: after the steel cage is tied, a standard steel formwork is used for construction, and the steel cage is wrapped. A release agent is applied to the inner side of the standard steel formwork, a water stop is affixed to the joints, grouting holes are installed at intervals of 1.5m and exhaust holes are installed at intervals of 1m on the top, and C60 self-compacting micro-expansive concrete is used for pouring. It is poured in sections from the bottom to the top, and each section is 2m long. The inserted vibrator and the vibrator attached to the outside of the formwork are vibrated together.

[0012] In S5: according to the construction progress, the load transfer is carried out in stages, and the supporting structure is removed, and the hydraulic jack is used for unloading in 4 stages. The hydraulic jack releases 25% of the load-bearing capacity every 6 hours, and the fiber grating sensor is used to synchronously monitor the strain and deflection of the wrapped area with the total station. After the construction is completed, the annular support is removed, and the four corner supports are retained until the concrete strength reaches 100%. The temporary support is cut and cut off in sections using a grinding wheel saw.

[0013] In step S6, cracks in the encapsulated area are detected using a crack width gauge, settlement differences of surrounding columns are monitored using an electronic level, and density of concrete in the encapsulated area is detected using ultrasound.

[0014] In summary, the present application includes at least one of the following beneficial technical effects: 1. By wrapping the original column roots and connecting them into an integral beam system, the loads of the original four columns can be transferred to the surrounding column groups. After only a few columns in the construction area are removed, columns are added at other new locations, and the surrounding structures of the removed columns are reinforced. The final approach in the project is to completely remove the structure in this area, together with the displaced columns, and re-build the support for the newly built reinforcement area in this area. Therefore, during the construction process, after the columns of the construction itself are removed, the columns are no longer rebuilt elsewhere, but the root area of ​​the original columns is converted into a rigid node of the beam. Only the roots of the original columns are retained in the wrapping area, and the upper columns are completely removed to form a column-free space. The load is transferred to the adjacent structure through the wrapping area, rather than relying on the vertical support of the original column position, so as to realize the removal of the columns at the construction site and reduce the stress change problem at the corresponding nodes when the columns are removed; 2. When dismantling the original main body, a diamond wire saw is used to separate the main body in stages. Compared with the method of directly using a diamond wire saw to cut the main body, the stress change that occurs instantly during the cutting process can be greatly reduced. The cutting height of the original column is controlled through staged cutting. During each cutting process, the cut column is supported by the jack at the bottom, and the changes in the building during the cutting are monitored. After the monitoring is completed, the cut column is moved downward by the jack and dismantled or detached. Through the staged construction method, the cut column can be supported by the jack on the original column at the same time of cutting, so that the stress change of the original column can be maintained to a great extent, and emergency repair time can be provided for subsequent construction problems, such as excessive stress changes or wall cracks, so as to ensure the construction progress and construction safety. Therefore, it is much more convenient to construct than directly using a diamond wire saw to cut the column. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the construction process flow chart of this application; Figure 2 This is a schematic diagram of the structure of the main building before construction of the embodiment of the present application; Figure 3 This is a schematic diagram of the structure of the construction area after construction of the embodiment of the present application; Figure 4 is a front view structural schematic diagram of the column dismantled in the embodiment of the present application; Figure 5 This is a schematic diagram of the structure of the connection between the column and the long ribs in the embodiment of the present application; Figure 6 is a front view structural diagram of an embodiment of the present application in which column reinforcement is exposed; Explanation of the reference numerals in the accompanying drawings: 1. Main building; 2. Construction area; 3. Portal steel support; 4. Hydraulic synchronous jacking system; 5. Support column; 6. Column root; 7. Column reinforcement; 8. Long reinforcement; 9. Shear bolts; 10. Shaped steel formwork; 11. Vertical main reinforcement; 12. Stirrups; 13. Hydraulic jack. DETAILED DESCRIPTION

[0016] The following is combined with Figure 1 - Attachment Figure 6 , further details of this application are given.

[0017] Embodiment: A construction method for supporting beams and pulling out columns, comprising the following steps: S1. Demolition area selection: Determine the number of columns in the area to be demolished based on the column positions in the original design building main body 1 and the surrounding structural conditions; S2. Overall structural demolition: According to design requirements, the original columns and surrounding structures are completely demolished in sequence according to the construction sequence; S21, temporary support: install a portal steel support 3 around the column to be removed to form a closed stress ring, and set a hydraulic synchronous jacking system 4 on the top; S22, pre-reinforcement of peripheral columns: the peripheral columns are reinforced by enlarging the section method, and the peripheral support columns 5 are reinforced; S3, treatment of the pre-rooting part of the column removal: according to the construction design, the original designed columns are removed in sequence, and the column roots 6 retained after the construction of the original designed columns are used as reserved points to extend and reinforce the surrounding columns; S31. Demolition in stages: According to the construction design, demolition shall be carried out column by column in the order of diagonal lines of the construction surface. After each demolition, the deformation degree of the surrounding area of ​​the construction shall be monitored for 48 hours; S32, root section processing: roughen the reserved column root 6, expose the column reinforcement 7 and weld the extension reinforcement 8, and drill holes to implant the shear bolts 9; S4, Wrapping reinforcement construction: The root area of ​​the original column is converted into a rigid node of the beam; only the 6 roots of the original column are retained in the wrapping area, and the upper column is completely removed to form a column-free space. The load is transferred to the adjacent structure through the wrapping area; S41, steel cage binding: vertical main reinforcement 11, and welded with the original column reinforcement 7, and connected with the annular stirrup 12 by the vertical main reinforcement 11; S42, formwork support: use the standard steel formwork 10, apply the release agent on the inside, add the water stop strip at the joint, install the grouting hole and the exhaust hole; S42, concrete pouring: C60 self-compacting micro-expansive concrete is used for pouring, and it is poured in sections from the bottom to the top, and the inserted vibrator and the vibrator attached to the formwork are used for joint vibrating; S5. Load transfer and system conversion: During the construction process, load transfer is carried out in stages according to the construction progress, and the supporting structure is removed; S51, staged unloading: use hydraulic jacks to unload in 4 stages, with an interval of 6 hours between each stage, and simultaneously monitor the strain and deflection of the wrapping area; S52, support removal: after the construction is completed, remove the circumferential support and keep the four corner supports until the concrete strength reaches 100%, start cutting the temporary support and use a grinding wheel saw to cut it off section by section; S6. Inspection and acceptance: Carry out crack inspection in the package area, detection of settlement difference of surrounding columns and use ultrasonic detection to detect the density of concrete in the package area; In step S1: Use a 3D scanner to build a BIM model, and mark the positions of the four columns and the adjacent reinforcement structures. Use the BIM model to determine the scope of the package area, and verify the bearing capacity of the surrounding columns. The bearing capacity of the surrounding columns is calculated by the following formula: Stability factor, f c : Axial compressive strength of concrete, A c : Concrete cross-sectional area, f y ′ : Compressive strength of steel bars, A ′ s : area of ​​compressed steel bars; Accept the bearing capacity of the surrounding columns. When the bearing capacity does not meet the construction standards, carbon limit cloth will be used for reinforcement.

[0018] Among them, by wrapping the original column roots 6 and connecting them into an integral beam system, the load of the original four columns can be transferred to the surrounding column groups. Only a few columns in the construction area 2 are demolished, and columns are added at other new positions to reinforce the surrounding structures of the demolished columns. The final approach of the project is to demolish all the structures in this area, together with the displaced columns, and rebuild the new reinforcement area in this area as a whole. Therefore, during the construction process, after the columns of the construction itself are demolished, the columns are no longer rebuilt elsewhere. Instead, the root area of ​​the original columns is converted into a rigid node of the beam. Only the original column roots 6 are retained in the wrapping area, and the upper columns are completely demolished to form a column-free space. The load is transmitted to the adjacent structure through the wrapping area, rather than relying on the vertical support of the original column position, so as to realize the demolition of the columns at the construction site and reduce the stress change problem at the corresponding nodes when the columns are demolished.

[0019] In step S2: according to the design requirements, the original columns and surrounding structures are completely dismantled in sequence along the construction sequence, and the portal steel supports 3 are installed around the columns to be dismantled to form a closed force ring, and a hydraulic synchronous jacking system 4 is set on the top with an accuracy of ±1mm, which is pre-loaded to 150% of the design load; the peripheral columns are subjected to the enlarged section method, the surface is roughened and reinforced, and C40 concrete is cast with a thickness of ≥100mm to reinforce the support column 5 structure around the construction site. The hydraulic synchronous jacking system 4 is controlled synchronously at multiple points to The construction area 2 of the industrial building can perform millimeter-level displacement fine-tuning to ensure that the load is smoothly transferred to the temporary support or the new structure when the original column is removed, avoiding structural deformation or cracking due to uneven force. In addition, during the construction process, a load-balancing valve and a real-time monitoring sensor are installed during the construction process, and the electronic level in step S5 is used to monitor the construction settlement difference in real time, thereby reducing the risk of overload or decompression during the construction process to ensure construction safety. During the process of supporting beams and pulling out columns, the mechanical locking function of the hydraulic system can keep the load stable for a long time to avoid sudden collapse.

[0020] In step S3: the originally designed columns are dismantled in sequence, and the column roots 6 retained after the construction of the originally designed columns are used as reserved points to extend and reinforce the surrounding columns; according to the construction design, the columns are dismantled one by one in the order of the diagonal line of the construction surface, the first column is dismantled, and the second column is dismantled after each column, forming a dismantling layout of 1, 3, 2, and 4, and the roots of the dismantled columns are retained by 300mm to reserve construction positions for subsequent wrapping area construction, and each time the columns are dismantled, the construction is suspended for 48 hours to monitor the deformation degree around the construction site, and the retained column roots 6 are roughened with a concave-convex difference of ≥6mm, and the column reinforcement 7 is exposed and welded to the long reinforcement 8, and the shear bolts 9 are drilled and implanted. When the original columns are dismantled, they are separated in stages using a diamond wire saw, and compared with the method of directly using a diamond wire saw to complete the cutting of the main body, the stress changes that occur instantly during the cutting process can be greatly reduced. The cutting height of the original column is controlled through staged cutting, and in the process of each cutting, the cut The dropped main body is supported by the jack at the bottom, and the changes in the building during the cutting are monitored. After the monitoring is completed, the jack is raised and lowered to move the cut column downward and remove or detach it. Through the staged construction method, the cut column can be supported by the jack on the original column at the same time as the cutting, so that the stress change of the original column can be maintained to a great extent, and emergency repair time can be provided for subsequent construction problems, such as excessive stress change or wall cracking, so as to ensure the construction progress and construction safety. Therefore, it is much more convenient to construct than directly using a diamond wire saw to cut the column. Only the column structure is removed, but 300mm of the root is retained as the junction area between the new and old structures, and the cutting line is 500mm above the bottom elevation of the beam to ensure that the wrapped area does not occupy the use space, and after the column is removed, the column reinforcement 7 of the original column is exposed, and the long reinforcement 8 is welded based on the column reinforcement 7, wherein the diameter of the long reinforcement 8 is 25mm.

[0021] In step S4: the root area of ​​the original column is converted into a rigid node of the beam, and the upper column is completely removed to form a column-free space; the load is transferred to the adjacent structure wrapping area through the wrapping area, and only the 6 original column roots are retained, and the steel cage is tied with the 6 original column roots.

[0022] In step S4: after the steel cage is tied, the fixed steel formwork 10 is used for construction and the steel cage is wrapped. A release agent is applied to the inner side of the fixed steel formwork, a water stop is added to the joints, grouting holes are installed at intervals of 1.5m and exhaust holes are installed at intervals of 1M on the top, and C60 self-compacting micro-expansive concrete is used for pouring. It is poured in sections from the bottom to the top, and each section is 2m long. The inserted vibrator and the vibrator attached to the outside of the formwork are vibrated together.

[0023] In S5: according to the construction progress, the load is transferred in stages, and the supporting structure is removed. The hydraulic jack 13 is used to unload in 4 stages. Every 6 hours, the hydraulic jack 13 releases 25% of the bearing capacity, and the fiber grating sensor and the total station are used to synchronously monitor the strain and deflection of the wrapped area. The strain must be ≤150με, and the deflection must be ≤L / 400. The fiber grating sensor model is: JH-FBG-C1, and the total station model is: KTS-442R10U. After the construction is completed, the annular support is removed, and the four corner supports are retained until the concrete strength reaches 100%. Start cutting the temporary support and use a grinding wheel saw to cut it off section by section.

[0024] In step S6, a crack width meter is used to detect cracks in the wrapped area. The crack width meter model is: BJLF-2, and the detected crack should be ≤0.1mm. An electronic level is used to detect the settlement difference of the surrounding columns. The electronic level model is: DL-501, and the settlement difference should be ≤2mm. Ultrasonic wave is used to detect the density of concrete in the wrapped area. After the construction is completed, the reinforced wrapped area is inspected for cracks using a crack width meter to confirm whether the construction of the wrapped area meets the construction standards. The electronic level is used to inspect the construction area of ​​the construction building at the beginning of the construction. The entire construction stage is monitored, and data is recorded and compared every 24 hours to obtain the settlement degree of the column during the construction process, thereby facilitating the monitoring of the construction.

[0025] The implementation principle of the embodiment of the present application is as follows: based on the column positions in the original design building body 1 and the surrounding structural conditions, the number of columns in the area to be demolished is determined; according to the design requirements, the original columns and surrounding structures are completely demolished in sequence along the construction sequence; portal steel supports 3 are installed around the columns to be demolished to form a closed stress ring, and a hydraulic synchronous jacking system 4 is arranged on the top; the section enlargement method is adopted for the surrounding columns to reinforce the structure of the surrounding support columns 5 at the construction position; according to the construction design, the original design columns are demolished in sequence; and the column roots 6 retained after the construction of the original design columns are used as reserved points, which are extended to the surrounding columns and reinforced; according to the construction design, the columns are demolished one by one in the order of the diagonal lines of the construction surface; after each demolition, the deformation degree of the surrounding area of ​​the building construction is monitored for 48 hours; the retained column roots 6 are roughened, the column reinforcement 7 is exposed, and the long reinforcement 8 is welded, and the shear bolts 9 are drilled and implanted to convert the root area of ​​the original column into a rigid node of the beam; only the original column roots 6 are retained in the wrapped area The upper column is completely removed to form a column-free space. The load is transferred to the adjacent structure through the wrapped area. The vertical main reinforcement 11 is welded to the original column reinforcement 7, and the annular stirrups 12 are connected with the vertical main reinforcement 11. The standardized steel formwork 10 is used, and the release agent is applied to the inside. Waterstop is added to the joints, and grouting holes and exhaust holes are installed. C60 self-compacting micro-expansive concrete is used for pouring. It is poured in sections from the bottom to the top. The inserted vibrator is vibrated together with the vibrator attached to the outside of the formwork. During the construction process, the load is transferred in stages according to the construction progress, and the supporting structure is removed. The hydraulic jack 13 is used to unload in 4 levels, with an interval of 6 hours for each level. The strain and deflection of the wrapped area are monitored simultaneously. After the construction is completed, the annular support is removed, and the four corner supports are retained until the concrete strength reaches 100%. The temporary support is cut and removed in sections with a grinding wheel saw. The crack detection of the wrapped area, the settlement difference of the surrounding columns and the use of ultrasound to detect the density of the concrete in the wrapped area are carried out.

[0026] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A construction method for supporting beams and pulling out columns, characterized in that: The following steps are involved: S1. Demolition area selection: Determine the number of columns in the area to be demolished based on the column positions in the original design building and the surrounding structural conditions; S2. Overall structural demolition: According to design requirements, the original columns and surrounding structures are completely demolished in sequence according to the construction sequence; S21, temporary support: install portal steel supports around the columns to be removed to form a closed stress ring, and set up a hydraulic synchronous jacking system on the top; S22, Pre-reinforcement of peripheral columns: The peripheral columns are reinforced by enlarging the section and strengthening the peripheral support column structure; S3. Treatment of pre-rooting of columns: According to the construction design, the original designed columns are removed in sequence, and the column roots retained after the construction of the original designed columns are used as reserved points to extend and reinforce the surrounding columns; S31. Demolition in stages: According to the construction design, demolition shall be carried out column by column in the order of diagonal lines of the construction surface. After each demolition, the deformation degree of the surrounding area of ​​the construction shall be monitored for 48 hours; S32, root section treatment: roughen the reserved column roots, expose the column reinforcement and weld the extension reinforcement, and drill holes to implant shear bolts; S4, Wrapping reinforcement construction: The root area of ​​the original column is converted into a rigid node of the beam; only the root of the original column is retained in the wrapping area, and the upper column is completely removed to form a column-free space. The load is transferred to the adjacent structure through the wrapping area; S41, steel cage binding: vertical main reinforcement, welded with the original column reinforcement 7, and connected with the annular stirrups with the vertical main reinforcement; S42, Formwork support: Use standard steel formwork, apply release agent on the inside, add water stop strips at the joints, and install grouting holes and vent holes; S42, concrete pouring: C60 self-compacting micro-expansive concrete is used for pouring, and it is poured in sections from the bottom to the top, and the inserted vibrator and the vibrator attached to the formwork are used for joint vibrating; S5. Load transfer and system conversion: During the construction process, load transfer is carried out in stages according to the construction progress, and the supporting structure is removed; S51, Gradual unloading: Use hydraulic jacks to unload in 4 stages, with an interval of 6 hours between each stage, and simultaneously monitor the strain and deflection of the wrapping area; S52, support removal: after the construction is completed, remove the circumferential support and keep the four corner supports until the concrete strength reaches 100%, start cutting the temporary support and use a grinding wheel saw to cut it off section by section; S6. Inspection and acceptance: Carry out crack inspection on the wrapped area, detection of settlement difference of surrounding columns and use ultrasonic detection to detect the density of concrete in the wrapped area.

2. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S1: Use a 3D scanner to build a BIM model, and mark the positions of the four columns and the adjacent reinforcement structures. Use the BIM model to determine the scope of the package area, and verify the bearing capacity of the surrounding columns. The bearing capacity of the surrounding columns is calculated by the following formula: Stability factor, f c : Axial compressive strength of concrete, A c : Concrete cross-sectional area, f y ′ : Compressive strength of steel bars, A ′ s : Area of ​​steel bars under compression; Accept the bearing capacity of the surrounding columns. When the bearing capacity does not meet the construction standards, carbon limit cloth will be used for reinforcement.

3. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S2: according to the design requirements, the original columns and surrounding structures are completely dismantled in sequence along the construction sequence, and portal steel supports are installed around the columns to be dismantled to form a closed load ring, and a hydraulic synchronous jacking system is set on the top with an accuracy of ±1mm, which is pre-loaded to 150% of the design load; the peripheral columns are subjected to the expanded section method, the surface is roughened and reinforced, and C40 concrete is cast in a formwork with a thickness of ≥100mm to reinforce the peripheral support column structure of the construction site.

4. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S3: the originally designed columns are dismantled in sequence, and the column roots retained after the construction of the originally designed columns are used as reserved points to extend to and reinforce the surrounding columns; according to the construction design, the columns are dismantled one by one in the order of the diagonal line of the construction surface, the first column is dismantled, and the second column is dismantled after each column, forming a dismantling layout of 1, 3, 2, and 4, and the roots of the dismantled columns are retained by 300mm to reserve construction positions for subsequent construction of the wrapped area, and each time the columns are dismantled, the construction is suspended for 48 hours to monitor the degree of deformation around the construction site, and the retained column roots are roughened with a concave-convex difference of ≥6mm, and the column reinforcement is exposed and welded to extend the reinforcement, and shear bolts are drilled and implanted.

5. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S4: the root area of ​​the original column is converted into a rigid node of the beam, and the upper column is completely removed to form a column-free space; the load is transferred to the adjacent structure through the wrapping area, and only the root of the original column is retained in the wrapping area, and the steel cage is tied with the root of the original column.

6. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S4: after the steel cage is tied, a fixed steel formwork is used for construction, and the steel cage is wrapped. A release agent is applied to the inner side of the fixed steel formwork, a water stop is affixed to the joints, grouting holes are installed at intervals of 1.5m and exhaust holes are installed at intervals of 1M on the top, and C60 self-compacting micro-expansive concrete is used for pouring. It is poured in sections from the bottom to the top, and each section is 2m long. The inserted vibrator and the vibrator attached to the outside of the formwork are vibrated together.

7. A construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In S5: according to the construction progress, the load transfer is carried out in stages, and the supporting structure is removed, and the hydraulic jack is used for unloading in 4 stages. The hydraulic jack releases 25% of the load-bearing capacity every 6 hours, and the fiber grating sensor is used to synchronously monitor the strain and deflection of the wrapped area with the total station. After the construction is completed, the annular support is removed, and the four corner supports are retained until the concrete strength reaches 100%. The temporary support is cut and cut off in sections using a grinding wheel saw.

8. The construction method for supporting beams and pulling out columns according to claim 1, characterized in that: In step S6, cracks in the encapsulated area are detected using a crack width gauge, settlement differences of surrounding columns are monitored using an electronic level, and density of concrete in the encapsulated area is detected using ultrasound.

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