Method for demolishing and reconstructing existing buildings by using existing walls to form an I-shaped support structure

Abstract

The present invention discloses a method for demolishing and reconstructing an existing building by using existing walls to form an I-shaped supporting structure. The main building comprises a first building, a second building and a third building which are arranged in a stepped manner. The method comprises the following steps: S1, reinforcing the ground walls of the main building and constructing new steel columns at the ends of the reserved transverse walls; S2, synchronously demolishing the indoor walls of the first building, the second building and the third building layer by layer from top to bottom, leaving two transverse walls in the middle of the first building, the second building and the third building respectively as supporting transverse walls, and making the supporting transverse walls in each building form an I-shaped supporting structure with the outer longitudinal walls on the east and west sides; S3, constructing a new foundation; S4, constructing a new steel structure of the main building outside the supporting transverse wall area; S5, demolishing the supporting transverse walls, and constructing the remaining new steel structures of the main building.

Description

Technical Field

[0001] The invention relates to the technical field of existing building reconstruction construction, and in particular to a method for dismantling and reconstructing an existing building by utilizing existing walls to form an I-shaped supporting structure. Background Art

[0002] In actual projects, there are often a large number of old building structure demolition and reconstruction projects, many of which require retaining the original building's external dimensions and part of the structure, while the internal structure is demolished and reinforced. Taking a certain project as an example, the original structural system of the old building is a load-bearing masonry structure with vertical and horizontal walls. Each floor is equipped with structural columns and ring beams. The floor (roof) panels are prefabricated circular hole panels and partially cast-in-place panels. The demolition and reconstruction requires retaining the T-shaped brick-concrete structure walls on the east and west sides, demolishing the middle part of the horizontal wall, using a new steel structure inside, and making a mixed structure with the original retained structure, and changing the internal use function. The demolition of the internal walls makes the original structure incomplete, which poses a great safety hazard. During the construction process, the retained structure needs to be reinforced, and there are strict requirements for the demolition sequence and construction plan. At the same time, it is also necessary to construct the new structure for the reinforced structure, with high construction accuracy requirements and great construction difficulty. If all the above-ground parts are demolished before the new construction, it is necessary to design a new plan and drawings, which will lead to problems such as the inability to complete the construction drawing review, thereby affecting the construction progress. Summary of the invention

[0003] The object of the present invention is to provide a method for demolishing and reconstructing an existing building by using existing walls to form an I-shaped support structure, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above-mentioned object, the present invention provides a method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure. The existing building includes a main building, the main building structure system is a longitudinal and transverse wall load-bearing structure, the foundation form is a strip foundation, and the main building includes a first building body, a second building body and a third building body arranged in a stepped manner. The method for demolishing and reconstructing an existing building includes the following steps:

[0005] S1. Strengthen the ground walls of the main building and construct additional steel columns at the ends of the retained transverse walls;

[0006] S2. The interior walls of the first, second and third buildings are demolished layer by layer from top to bottom. Two horizontal walls are left in the middle of the first, second and third buildings respectively to serve as supporting horizontal walls, and the supporting horizontal walls in each building form an I-shaped supporting structure with the outer longitudinal walls on the east and west sides;

[0007] S3, new foundation construction;

[0008] S4. Construction of new steel structure of the main building outside the supporting cross wall area;

[0009] S5. Remove the supporting cross walls and construct the remaining steel structure of the main building.

[0010] In a preferred embodiment, in step S1, reinforcing the ground wall of the main building and constructing new steel columns at the ends of the retained transverse walls include the following steps:

[0011] S11. Strengthen the exterior longitudinal walls of the main building above the outdoor ground floor layer by layer from bottom to top, install the angle steel reinforcement of the roof panels corresponding to the newly added steel columns on the top floor, and shave and chisel holes in the floor slabs of each floor;

[0012] S12, partially cutting the horizontal wall along the vertical direction at the newly added steel column installation positions on each floor of the first building, the second building, and the third building, and installing a reinforcement structure, wherein a set of reinforcement structures is immediately installed after each partial cutting of the horizontal wall is completed;

[0013] S23. After the local cutting is completed, install new steel columns at the ends of the retained transverse walls close to the outer longitudinal walls. When installing the new steel columns, temporarily remove the reinforcement structures at the corresponding positions of the new steel columns. However, the reinforcement structures of the adjacent axes shall not be removed at the same time. After the construction of the new steel columns is completed, immediately restore the reinforcement structures.

[0014] In a preferred embodiment, in step S2, the indoor walls of the first building, the second building and the third building are synchronously demolished layer by layer from top to bottom, including the following steps:

[0015] S21. Divide the first building, the second building and the third building into regions. The first building has three floors, the second building has four floors, and the third building has five floors. The first building is evenly divided from south to north into axes 1 to 6, the second building is evenly divided from south to north into axes 7 to 12, and the third building is evenly divided from south to north into axes 13 to 18;

[0016] S22. According to the construction drawings and mechanical calculations, it is determined that two transverse walls are left in the middle of the first building, the second building and the third building respectively. Among them, the transverse walls of the 3rd and 4th axes of the first building are not to be demolished, the two transverse walls of the 9th and 10th axes of the second building are not to be demolished, and the two transverse walls of the 15th and 16th axes of the third building are not to be demolished, and the structure between the two transverse walls is retained and not to be demolished;

[0017] S23. From top to bottom, the interior walls of the first, second and third buildings are dismantled manually and layer by layer simultaneously, and vertical transportation is carried out by crane.

[0018] In a preferred embodiment, step S2 further includes:

[0019] S24. After the inner wall of the top floor of the first building is removed, a single steel beam is arranged on the outer side of the top floor of the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns;

[0020] S25. After the inner wall on the top floor of the second building is removed, a single steel beam is set on the side of the top floor of the second building close to the first building. After the inner wall on the second floor of the second building is removed, a single steel beam is set on the side of the second floor of the second building close to the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns;

[0021] S26. After the inner wall of the top floor of the third building is demolished, a single steel beam is set on the north and south sides of the top floor of the third building respectively. After the inner wall of the third floor of the third building is demolished, a single steel beam is set on the north and south sides of the third floor of the third building respectively, and the two ends of the steel beam are hinged to the newly added steel columns respectively.

[0022] In a preferred embodiment, in step S3, the new foundation construction includes the following steps:

[0023] The center line of the main building along the east-west direction is divided into the first-stage excavation area and the second-stage excavation area. The indoor and outdoor areas of the first-stage excavation area are excavated simultaneously, and the brick wall foundation is enlarged and reinforced, and the steel structure is newly added with an independent foundation. 100mm thick concrete is poured from the elevation above -3.5 meters to the outdoor ground elevation, and C30 commercial concrete is poured below the elevation of -3.5 meters;

[0024] The indoor soil in the first phase excavation area is temporarily piled up in the second phase excavation area after excavation, and the outdoor soil is temporarily piled up nearby. After the first phase of construction is completed, the soil is backfilled;

[0025] After backfilling to the specified elevation, the second phase of excavation area will be excavated simultaneously indoors and outdoors, and the brick wall foundation cross-section will be expanded and reinforced, and a new independent foundation for the steel structure will be constructed. 100mm thick concrete will be poured from the -3.5m elevation to the outdoor ground elevation, and C30 commercial concrete will be poured below the -3.5m elevation.

[0026] In a preferred embodiment, the installation position of new steel columns on each floor of the first building, the second building and the third building is the two supporting horizontal walls except the first building, the second building and the third building. When constructing the new steel columns, first cut the wall below the ground beam at the installation position of the new steel columns, without cutting the ground beam, and make a vertical cut on the horizontal wall below the ground beam at the installation position of the steel columns. Manually transport the new steel columns from the adjacent windows, place them obliquely into the incisions, and install and fix them. After the installation is completed, the new steel columns are vertically set in the incisions. The tops of the new steel columns are 200 mm away from the lowest point of the ground beams, and the bottoms of the new steel columns are fixedly connected to the ground beams of the original structure through mechanical anchors.

[0027] In a preferred embodiment, the original walls of each floor are cut by a rope saw. The rope saw is installed on the roof. The diamond rope is turned by the steering wheel, extending from the floor opening to the first floor, and then back to the roof. After installation, the horizontal wall is cut. The cutting of each part is formed at one time from the first floor to the top floor. After each cutting is completed, the corresponding wall is shaved and removed, and a reinforcement structure is installed. After cutting, the part close to the retained horizontal wall forms a T-shaped wall with the outer longitudinal wall.

[0028] In a preferred embodiment, in step S4, construction of a new steel structure of the main building is carried out outside the supporting cross wall area, including: constructing the indoor steel beam-column system layer by layer from the first floor upwards, and fixing it with the newly constructed steel columns to form an overall steel frame structure.

[0029] In a preferred embodiment, in step S5, the supporting transverse walls are demolished and the construction of the remaining new steel structure of the main building is carried out, including: the two supporting transverse walls of the first building, the second building, and the third building and the structure between the two transverse walls are simultaneously demolished, and the construction of the remaining new steel structure of the main building is carried out according to the drawings, wherein the structure between the two transverse walls includes transverse and longitudinal walls and floor slabs.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the method of the present invention is aimed at the demolition and reconstruction of the main building with different buildings with stepped heights. The demolition and reconstruction requires retaining the T-shaped brick-concrete structure walls on the east and west sides, demolishing the cross wall in the middle part, adopting a new steel structure inside, making a mixed structure with the original retained structure, and changing the internal use function. The present invention leaves the cross walls in the middle of the first building, the second building and the third building respectively without demolition, so that the supporting cross walls in each building and the outer longitudinal walls on the east and west sides form an I-shaped support structure, maximizing the use of the existing walls as temporary support structures, which is very beneficial to the safety of demolition and the investment in temporary measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the method for demolishing and renovating an existing building of the present invention;

[0032] Figure 2 This is a schematic diagram of an I-shaped support structure model of the present invention;

[0033] Figure 3 This is a schematic diagram of the construction of a newly added steel column at the end of the retained transverse wall of the present invention;

[0034] Figure 4 This is a schematic diagram of the construction position of newly added steel columns and newly added steel beams at the end of the retained transverse wall of the present invention;

[0035] Figure 5 It is a schematic diagram of the roof panel reinforcement plane of the present invention;

[0036] Figure 6This is a schematic diagram of the roof panel reinforcement elevation of the present invention;

[0037] Figure 7 It is a schematic diagram of the support cross wall area and axis division of the present invention;

[0038] Figure 8 It is a schematic diagram of the earth excavation area of ​​the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention are described clearly and completely below. The embodiments of the present invention and all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0040] This embodiment takes a demolition and reconstruction project of an old building as an example. The main building structure type is a masonry structure. The original use is dormitory. The main building includes a three-story first building, a four-story second building, and a five-story third building from south to north. The seismic fortification category is Class C. The building height is 17.8 meters, and the foundation form is a strip foundation. The original structural system of the main building is a longitudinal and transverse wall load-bearing structure, the foundation form is a strip foundation, the thickness of the external load-bearing wall is 370mm, the thickness of the internal wall is 240mm, each floor is equipped with structural columns and ring beams, the floor (roof) panel is a prefabricated circular hole plate, and the local cast-in-place plate. The maximum length of the building from north to south is 61.2 meters, the width from east to west is 17.45 meters, the bay is 3.6 meters, the depth is 7.64 meters, the passage width is 1.8 meters, the floor height is 3.2 meters, and the height difference between indoor and outdoor is 0.6 meters. The number of floors remains unchanged after the renovation. The structural system after the reinforcement and renovation is a mixed structure of steel structure + masonry. The building height after the renovation is 18.1 meters. The main functional area has four floors and some parts have five floors. The foundation of the newly erected steel column in the middle is an independent foundation. The main building retains the T-shaped brick walls on the east and west sides, which are reinforced with reinforced concrete surface layers, and a new steel structure is used inside.

[0041] like Figures 1 to 8 As shown, the existing building demolition and reconstruction method of the present invention comprises the following steps:

[0042] Step S1: Reinforce the ground walls of the main building and construct new steel columns at the ends of the retained transverse walls.

[0043] Specifically, in step S1, the reinforcement of the ground wall of the main building and the construction of additional steel columns at the ends of the retained transverse walls include the following steps:

[0044] Step S11, reinforce the outer longitudinal wall 201 above the outdoor ground of the main building layer by layer from bottom to top, and simultaneously install the L80×5 angle steel 501 of the roof panel 502 corresponding to the newly added steel column 301 on the top layer, and fix it with tension bolts 402, and shave and chisel holes in the floor slabs of each layer, and the size of the hole 601 is 700×800mm;

[0045] Step S12: Partially cut the horizontal wall along the vertical direction and install the reinforcement structure at the installation position of the newly added steel column 301 on each floor of the first building 901, the second building 902 and the third building 903, wherein a set of reinforcement structures is installed immediately after each partial cutting of the horizontal wall is completed. The reinforcement structure is double channel steel, and the double channel steels on both sides of the wall are fixed by tension bolts.

[0046] Step S23, after the local cutting is completed, a new steel column 301 is installed at the end of the retained transverse wall 202 close to the outer longitudinal wall 201. When the new steel column is installed, the reinforcement structure at the corresponding position of the new steel column 301 is temporarily removed, but the reinforcement structure of the adjacent axis shall not be removed at the same time. After the construction of the new steel column is completed, the reinforcement structure is immediately restored.

[0047] Furthermore, the installation positions of the newly added steel columns on each floor of the first building 901, the second building 902 and the third building 903 are the two supporting horizontal walls 203 except the first building, the second building and the third building. When constructing the newly added steel columns, first cut the wall below the ground beam 302 at the installation position of the newly added steel columns 301, without cutting off the ground beam 302, and make a vertical cut on the horizontal wall at the installation position of the steel columns below the ground beam 302. Manually transport the newly added steel columns 301 from the nearby windows, place them obliquely into the incisions, and install and fix them. After the installation is completed, the newly added steel columns 301 are vertically set in the incisions. The top of the newly added steel columns is 200 mm away from the lowest point of the ground beam 302, and the bottom of the newly added steel columns is fixedly connected to the ground beams of the original structure by mechanical anchors.

[0048] The original walls of each floor are cut by a rope saw. The rope saw is installed on the roof. The diamond rope is turned by the steering wheel, extending from the floor opening to the first floor, and then back to the roof. After installation, the horizontal wall is cut. The cutting of each part is formed at one time from the first floor to the top floor. After each cutting is completed, the corresponding wall is shaved and removed, and a reinforcement structure is installed. After cutting, a T-shaped wall is formed close to the retained horizontal wall 202 and the outer longitudinal wall 201.

[0049] The demolition of the floor slabs is as follows: before demolition, the structural floor slabs of the original main building structure are registered, and different demolition sequences are adopted for different floor slabs; the prefabricated slabs are demolished first, and then the cast-in-place slabs.

[0050] Step S2, synchronously dismantle the interior walls of the first building 901, the second building 902 and the third building 903 layer by layer from top to bottom, wherein two supporting transverse walls 203 are respectively left in the middle of the first building, the second building and the third building, so that the supporting transverse walls 203 in each building and the outer longitudinal walls on the east and west sides form an I-shaped supporting structure. Specifically, the steps include:

[0051] Step S21, dividing the first building 901, the second building 902 and the third building 903 into regions, the first building 901 has three floors, the second building 902 has four floors, the third building 903 has five floors, the first building 901 is evenly divided into axes 1 to 6 from south to north, the second building 902 is evenly divided into axes 7 to 12 from south to north, and the third building 903 is evenly divided into axes 13 to 18 from south to north;

[0052] Step S22: According to the construction drawings and mechanical calculations, it is determined that two transverse walls are left in the middle of the first building, the second building, and the third building as supporting transverse walls 203, wherein the transverse walls of the 3rd and 4th axes of the first building are not removed, the two transverse walls of the 9th and 10th axes of the second building are not removed, the two transverse walls of the 15th and 16th axes of the third building are not removed, and the structure between the two transverse walls is retained and not removed;

[0053] Step S23: From top to bottom, manually dismantle the interior walls of the first building, the second building and the third building layer by layer, and use a crane for vertical transportation.

[0054] Step S24: after the inner wall of the top floor of the first building is removed, a single steel beam is arranged on the outer side of the top floor of the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns;

[0055] Step S25: after the inner wall of the top floor of the second building is removed, a single steel beam is arranged on the side of the top floor of the second building close to the first building; after the inner wall of the second floor of the second building is removed, a single steel beam is arranged on the side of the second floor of the second building close to the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns;

[0056] Step S26: After the inner wall of the top floor of the third building is demolished, a single steel beam is set on the north and south sides of the top floor of the third building respectively; after the inner wall of the third floor of the third building is demolished, a single steel beam is set on the north and south sides of the third floor of the third building respectively, and both ends of the steel beam are hinged to the newly added steel columns respectively.

[0057] Step S3: New foundation construction, including the following steps:

[0058] The center line of the main building along the east-west direction is divided into the first-stage excavation area 801 and the second-stage excavation area 802. The indoor and outdoor areas of the first-stage excavation area are excavated simultaneously, and the brick wall foundation is enlarged and reinforced, and the steel structure is newly added with an independent foundation. 100mm thick concrete 204 is poured from the elevation above -3.5 meters to the outdoor ground elevation, and C30 commercial concrete is poured below the elevation of -3.5 meters;

[0059] The indoor soil in the first phase excavation area is temporarily piled up in the second phase excavation area after excavation, and the outdoor soil is temporarily piled up nearby. After the first phase of construction is completed, the soil is backfilled;

[0060] After backfilling to the specified elevation, the second phase of excavation area will be excavated simultaneously indoors and outdoors, and the brick wall foundation cross-section will be expanded and reinforced, and a new independent foundation for the steel structure will be constructed. 100mm thick concrete will be poured from the -3.5m elevation to the outdoor ground elevation, and C30 commercial concrete will be poured below the -3.5m elevation.

[0061] Step S4, construct a new steel structure of the main building outside the supporting cross wall area: construct the indoor steel beam-column system from the first floor upwards layer by layer, and fix it with the newly added steel columns that have been constructed to form an overall steel frame structure, and set viscous dampers to enhance the seismic performance of the structure.

[0062] Step S5, demolish the supporting transverse walls and construct the remaining new steel structure of the main building: simultaneously demolish the two supporting transverse walls of the first building, the second building, and the third building and the structure between the two supporting transverse walls, and construct the remaining new steel structure of the main building according to the drawings, wherein the structure between the two supporting transverse walls includes horizontal and vertical walls and floor slabs.

[0063] In a preferred embodiment, the newly added steel columns are installed in sections, with the underground part being one section, the first building body being one section, the second building body being two sections, the first to third floors of the third building being one section, and the fourth to fifth floors being one section. Newly added steel beams 303 are installed between two adjacent newly added steel columns, with one newly added steel beam installed in each section. Both the newly added steel columns and the newly added steel beams are installed using a truck crane.

[0064] The structural system after transformation is:

[0065] 1. Vertical structural system:

[0066] (1) Retain the deadweight of the wall and transfer it to the foundation through the masonry itself;

[0067] (2) Retain the load of the cast-in-place floor slab and transfer it to the foundation through the steel structure;

[0068] (3) The load of the newly built part is transmitted to the foundation through the steel structure.

[0069] 2. Lateral force resisting structural system:

[0070] (1) A double lateral force resistance system is formed by reinforced concrete walls + steel frames;

[0071] (2) When moderate and large earthquakes occur, the damper provides energy dissipation and shock absorption, reducing the seismic response.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure, characterized in that: The existing building includes a main building, the structural system of the main building is a longitudinal and transverse wall load-bearing structure, the foundation form is a strip foundation, and the main building includes a first building body, a second building body and a third building body arranged in a stepped manner. The existing building demolition and reconstruction method includes the following steps: S1. Strengthen the ground walls of the main building and construct additional steel columns at the ends of the retained transverse walls; S2. The interior walls of the first, second and third buildings are demolished layer by layer from top to bottom. Two horizontal walls are left in the middle of the first, second and third buildings respectively to serve as supporting horizontal walls, and the supporting horizontal walls in each building form an I-shaped supporting structure with the outer longitudinal walls on the east and west sides; S3, new foundation construction; S4. Construction of new steel structure of the main building outside the supporting cross wall area; S5. Remove the supporting transverse wall and construct the remaining steel structure of the main building; Among them, in step S1, the reinforcement of the ground wall of the main building and the construction of additional steel columns at the ends of the reserved transverse walls include the following steps: S11. Strengthen the exterior longitudinal walls of the main building above the outdoor ground layer by layer from bottom to top, install the angle steel of the roof panels corresponding to the newly added steel columns on the top floor, and shave and chisel holes in the floor slabs of each floor; S12, partially cutting the horizontal wall along the vertical direction at the newly added steel column installation positions on each floor of the first building, the second building, and the third building, and installing a reinforcement structure, wherein a set of reinforcement structures is immediately installed after each partial cutting of the horizontal wall is completed; S13. After the local cutting is completed, install new steel columns at the ends of the retained transverse walls close to the outer longitudinal walls. When installing the new steel columns, temporarily remove the reinforcement structures at the corresponding positions of the new steel columns. However, the reinforcement structures of the adjacent axes shall not be removed at the same time. After the construction of the new steel columns is completed, immediately restore the reinforcement structures.

2. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 1, characterized in that: In step S2, the indoor walls of the first building, the second building, and the third building are synchronously demolished layer by layer from top to bottom, including the following steps: S21. Divide the first building, the second building and the third building into regions. The first building has three floors, the second building has four floors, and the third building has five floors. The first building is evenly divided into axes 1 to 6 from south to north, the second building is evenly divided into axes 7 to 12 from south to north, and the third building is evenly divided into axes 13 to 18 from south to north; S22. According to the construction drawings and mechanical calculations, it is determined that two transverse walls are left in the middle of the first building, the second building and the third building respectively. Among them, the transverse walls of the 3rd and 4th axes of the first building are not to be demolished, the two transverse walls of the 9th and 10th axes of the second building are not to be demolished, and the two transverse walls of the 15th and 16th axes of the third building are not to be demolished, and the structure between the two transverse walls is retained and not to be demolished; S23. From top to bottom, the interior walls of the first, second and third buildings are dismantled manually and layer by layer simultaneously, and vertical transportation is carried out by crane.

3. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 2, characterized in that: Step S2 also includes: S24. After the inner wall of the top floor of the first building is removed, a single steel beam is arranged on the outer side of the top floor of the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns; S25. After the inner wall on the top floor of the second building is removed, a single steel beam is set on the side of the top floor of the second building close to the first building. After the inner wall on the second floor of the second building is removed, a single steel beam is set on the side of the second floor of the second building close to the first building, and both ends of the steel beam are respectively hinged to the newly added steel columns; S26. After the inner wall of the top floor of the third building is demolished, a single steel beam is set on the north and south sides of the top floor of the third building respectively. After the inner wall of the third floor of the third building is demolished, a single steel beam is set on the north and south sides of the third floor of the third building respectively, and the two ends of the steel beam are hinged to the newly added steel columns respectively.

4. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 3, characterized in that: In step S3, new foundation construction is performed, including the following steps: The center line of the main building along the east-west direction is divided into the first-stage excavation area and the second-stage excavation area. The indoor and outdoor areas of the first-stage excavation area are excavated simultaneously, and the brick wall foundation is enlarged and reinforced, and the steel structure is newly added with an independent foundation. 100mm thick concrete is poured from the elevation above -3.5 meters to the outdoor ground elevation, and C30 commercial concrete is poured below the elevation of -3.5 meters; The indoor soil in the first phase excavation area is temporarily piled up in the second phase excavation area after excavation, and the outdoor soil is temporarily piled up nearby. After the first phase of construction is completed, the soil is backfilled; After backfilling to the specified elevation, the second phase of excavation area will be excavated simultaneously indoors and outdoors, and the brick wall foundation cross-section will be expanded and reinforced, and a new independent foundation for the steel structure will be constructed. 100mm thick concrete will be poured from the -3.5m elevation to the outdoor ground elevation, and C30 commercial concrete will be poured below the -3.5m elevation.

5. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 4, characterized in that: When constructing new steel columns, first cut the wall below the ground beam where the new steel columns will be installed. Do not cut the ground beam, and make vertical cuts on the horizontal wall below the ground beam where the steel columns will be installed. Manually transport the new steel columns from the adjacent windows, place them obliquely into the cuts, and install and fix them. After the installation is completed, the new steel columns are set vertically in the cuts. The top of the new steel columns is 200mm away from the lowest point of the ground beam, and the bottom of the new steel columns is fixedly connected to the ground beam of the original structure through mechanical anchors.

6. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 5, characterized in that: The original walls of each floor above ground are cut by a rope saw. The rope saw is installed on the roof. The diamond rope is turned by the steering wheel, extending from the floor opening to the first floor, and then back to the roof. After installation, the horizontal wall is cut. The cutting of each part is formed at one time from the first floor to the top floor. After each cutting is completed, the corresponding wall is shaved and removed, and the reinforcement structure is installed. After cutting, the part close to the retained horizontal wall forms a T-shaped wall with the outer longitudinal wall.

7. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 6, characterized in that: In step S4, the new steel structure of the main building is constructed outside the supporting cross wall area, including: constructing the indoor steel beam-column system from the first floor upwards layer by layer, and fixing it with the newly constructed steel columns to form an overall steel frame structure.

8. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 7, characterized in that: In step S5, the supporting transverse walls are demolished, and the construction of the remaining new steel structure of the main building is carried out, including: the two supporting transverse walls of the first building, the second building, and the third building and the structure between the two transverse walls are demolished simultaneously, and the construction of the remaining new steel structure of the main building is carried out according to the drawings, wherein the structure between the two transverse walls includes transverse and longitudinal walls and floor slabs.

9. The method for demolishing and reconstructing an existing building using an existing wall to form an I-shaped support structure according to claim 8, characterized in that: The newly added steel columns are installed in sections, with the underground part as one section, the first building of the above-ground part as one section, the second building as two sections, the first to third floors of the third building as one section, and the fourth to fifth floors as one section. New steel beams are installed between two adjacent new steel columns, with one new steel beam installed in each section. The new steel columns and steel beams are installed using truck cranes.

Images