Construction method of demolition and reconstruction of old building structure using permanent and temporary truss support

Abstract

The invention discloses a method for dismantling and reconstructing an old building structure by using a truss support combined with permanent and temporary structures. The main building comprises different buildings arranged in a stepped manner, and the method comprises the following steps: S1, reinforcing the foundation of the main building; S2, reinforcing the ground walls of the main building; S3, dismantling and reinforcing the truss support system of the main building by area and floor; S4, indoor earth excavation; S5, indoor independent foundation construction and earth backfilling; S6, constructing a new steel structure of the main building; wherein, in step S3, dismantling and reinforcing the truss support system of the main building by area and floor, the indoor area load-bearing walls of the main building are dismantled layer by layer and section by section in the order of from top to bottom, from south to north, and first horizontally and then vertically, and the brick-concrete structure walls on the east and west sides are retained as a whole, and as the layers are dismantled layer by layer, the reinforced truss support system is installed layer by layer from top to bottom.

Description

Technical Field

[0001] The invention relates to the technical field of old building structure reconstruction construction, and in particular to a construction method for dismantling and reconstructing an old building structure by using a permanent and temporary combined truss support. 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 dismantling and reinforcing the internal structure. Taking a certain project as an example, the original structural system of the old building is a load-bearing structure of vertical and horizontal walls, each floor is equipped with structural columns and ring beams, the floor (roof) panels are prefabricated circular hole panels, and some are 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 horizontal wall in the middle, 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, posing a major 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, which requires high construction accuracy and is difficult to construct. Summary of the invention

[0003] The purpose of the present invention is to provide a construction method for dismantling and reconstructing an old building structure by supporting a permanent and temporary truss, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides a construction method for demolishing and reconstructing an old building structure using a permanent and temporary truss support, wherein the old building structure 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 different building bodies arranged in a stepped manner. The construction method for demolishing and reconstructing the old building structure includes the following steps:

[0005] S1. Strengthen the foundation of the main building;

[0006] S2. Strengthen the ground walls of the main building;

[0007] S3: Dismantle and reinforce the truss support system of the main building in different areas and floors;

[0008] S4, indoor earth excavation;

[0009] S5. Indoor independent foundation construction and earth backfilling;

[0010] S6. Construction of new steel structure of main building;

[0011] Among them, in step S3, the main building is dismantled and reinforced in sections and floors by area. The load-bearing walls of the indoor area of ​​the main building are dismantled layer by layer and section by section in the order from top to bottom, from south to north, and first horizontally and then vertically. The brick-concrete structure walls on the east and west sides are retained as a whole. As the walls are dismantled layer by layer, the reinforced truss support system is installed layer by layer from top to bottom.

[0012] In a preferred embodiment, in step S1, the foundation of the main building is reinforced, including: S11, symmetrical excavation and support of earth on both sides of the interior and exterior of the main building; S12, after the excavation of earth in all areas is completed, the strip foundation of the retained exterior wall on the east and west sides of the underground is expanded and reinforced, the retained transverse wall part and the retained exterior wall form a T-shaped wall, the wall is statically cut on one side of the retained transverse wall part, and new steel columns are constructed; S13, earth backfilling.

[0013] In a preferred embodiment, in step S2, the ground wall of the main building is reinforced, including: S21, reinforcing the longitudinal walls of the main building above the outdoor ground layer by layer from bottom to top, and simultaneously installing the angle steel reinforcement of the roof panel corresponding to the position of the newly added steel column on the top layer, and shaving holes in the floor slabs of each layer; S22, cutting the horizontal walls vertically at the installation positions of the newly added steel columns on each floor of different buildings and installing reinforcement structures, wherein a group of reinforcement structures is installed immediately after each horizontal wall cutting is completed; S23, installing new steel columns and steel beams at the ends of the retained horizontal walls, so that some of the new steel columns and steel beams can be used as temporary supports during the demolition process. When the new steel columns are installed, the reinforcement structures are temporarily removed at the corresponding positions of the new steel columns, but the reinforcement structures of adjacent axes shall not be removed at the same time. After the construction of the new steel columns is completed, the reinforcement structures are immediately restored.

[0014] In a preferred embodiment, in step S3, the main building is dismantled and reinforced by the truss support system in different areas and floors. The load-bearing walls of the indoor area of ​​the main building are dismantled layer by layer and section by section in the order of top-down, south-to-north, first horizontal and then vertical components, and the brick-concrete structure walls on the east and west sides are retained as a whole. As the walls are dismantled layer by layer, the reinforced truss support system is installed layer by layer from top to bottom, including: S31, different buildings of the main building are divided into regions, wherein the main building includes a first building, a second building and a third building connected in sequence from south to north. 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; S32. Determine the demolition sequence and reinforcement truss installation sequence of different floors of different buildings according to the construction drawings; S33. Gradually demolish the walls from south to north and simultaneously install the reinforcement truss support system.

[0015] In a preferred embodiment, step S32, determining the demolition sequence of different floors of different buildings and the installation sequence of reinforcement trusses according to the construction drawings, includes:

[0016] S321, demolition of the 1st to 6th axis of the top floor of the first building and the 1st to 3rd axis of the second top floor;

[0017] S322, construction of the first reinforcement truss on the top floor of the first building;

[0018] S323, partial demolition of the original structure of the first floor and second floor of the first building;

[0019] S324, demolition of the 6th to 10th axis area on the top floor and the second top floor of the second building;

[0020] S325, construction of the second reinforcement truss on the top floor of the first building and the first reinforcement truss on the top floor of the second building;

[0021] S326: demolition of the remaining area of ​​the first building, the first floor of the second building, and part of the original structure of the second floor;

[0022] S327, construction of the first reinforcement truss at the third floor of the second building;

[0023] S328, demolition of the top and second top floors of the northern half of the second building, and the top and second top floors of the third building;

[0024] S329, construction of the second reinforcement truss on the top floor of the second building and the first reinforcement truss on the fourth floor of the third building;

[0025] S330, the remaining area of ​​the second building, and the original structures from the first to the third floors of the southern half of the third building were demolished;

[0026] S331, the original structure of the top floor and the second top floor of the northern half of the third building were demolished;

[0027] S332, installation of the second reinforcement truss at the fourth floor of the third building;

[0028] S333, the remaining original structure of the third building was demolished;

[0029] S334. The second reinforcement truss on the third floor of the third building was installed, the wall was demolished, and a reinforcement truss support system was formed.

[0030] In a preferred embodiment, the reinforcement truss of the first building is a single-layer chord truss, and two single-layer chord trusses are symmetrically arranged on the north and south sides of the top floor of the first building, and the single-layer chord truss includes two groups of first chords, second chords and multiple temporary supporting round bars arranged parallel to the cross wall, wherein the first chord is located at both ends of the second chord, and the outer ends of the first chord are respectively fixedly connected to the newly added steel columns, and the ends of the temporary supporting round bars located on the outside are fixedly connected to the newly added steel columns.

[0031] In a preferred embodiment, the reinforcement trusses of the second building and the third building are both three-layer chord trusses, and two three-layer chord trusses are respectively arranged on the north and south sides of the second building / third building, and the three-layer chord trusses include a first-layer chord frame, a second-layer chord truss, a third-layer chord truss, a vertical connecting chord and a plurality of temporary supporting round rods, wherein the first-layer chord frame, the second-layer chord truss, the two ends of the third-layer chord truss and the ends of the temporary supporting round rods located on the outside are fixedly connected to the newly added steel columns.

[0032] In a preferred embodiment, when new steel columns are constructed, the original walls of each floor are cut by a rope saw. The rope saw is installed on the roof, and the diamond rope is turned by a steering wheel. It extends from the floor opening to the first floor and then back to the roof. After it is installed in place, the brick wall is cut. The cutting of each part is completed at one time from the first floor to the top floor. After each cutting is completed, the corresponding wall is shaved and demolished, and a reinforcement structure is installed.

[0033] In a preferred embodiment, newly added steel columns and steel beams are installed at the ends of the retained cross walls, including: the underground part of the newly added steel column connected to the retained cross wall is one section, the first building body on the ground is one section, the second building body is two sections, the first to third floors of the third building are one section, and the fourth to fifth floors are one section. The newly added steel beams are installed in one section, and the newly added steel columns and steel beams are installed using a truck crane.

[0034] In a preferred embodiment, in step S6, the construction of the new steel structure of the main building includes: when constructing the new steel structure of the main building, only the temporary supporting round bars in the reinforced truss support system are removed, based on retaining the newly installed steel columns and steel beams at the ends of the cross walls and the reinforced truss support system after the temporary supporting round bars are removed, the indoor steel beam and column system is constructed layer by layer from the first floor upwards to form an overall steel frame structure.

[0035] 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 arranged in a stepped manner, and adopts a combination of permanent and temporary methods. Some steel columns and steel beams of the newly built structure are used as temporary supports during the demolition process, and are installed first, and the truss support system is newly reinforced, which saves steel and construction period, and achieves better economic benefits. The present invention demolishes the load-bearing walls of the indoor area of ​​the main building layer by layer and section by section in the order of top-down, from south to north, first horizontal and then vertical components by demolishing the main building by area and floor, and the brick-concrete structure walls on the east and west sides are retained as a whole, and the reinforced truss support system is installed layer by layer from top to bottom as the layers are demolished layer by layer. When the new steel structure of the main building is constructed in the later stage, the installed reinforced truss support system can be used to construct the indoor steel beam and column system, which saves steel and construction period, and ensures overall stability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1It is a flow chart of the construction method for dismantling and renovating an old building structure of the present invention;

[0037] Figure 2 It is a schematic diagram of the outer longitudinal wall reinforcement of the present invention;

[0038] 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;

[0039] Figure 4 It is a schematic diagram of the vertical and horizontal wall connection reinforcement section of the present invention;

[0040] Figure 5 It is a schematic diagram of the roof panel reinforcement plane of the present invention;

[0041] Figure 6 This is a schematic diagram of the roof panel reinforcement elevation of the present invention;

[0042] Figure 7 It is a schematic diagram of a floor panel opening of the present invention;

[0043] Figure 8 A schematic diagram of the construction of newly added steel columns and steel beams at the end of the retained transverse wall of the present invention;

[0044] Fig. 9 It is a schematic diagram of the wall demolition area and axis division of the present invention;

[0045] FIG. 10A to FIG. 10N It is a schematic diagram of the construction process of dismantling and reinforcing the truss support system of the main building by area and floor according to the present invention;

[0046] Fig.11 It is a plan view of the reinforcement truss of the present invention after construction is completed;

[0047] Fig.12 for Fig.11 Schematic diagram of the AA section;

[0048] Fig.13 for Fig.11 Schematic diagram of the middle BB section;

[0049] Fig.14 for Fig.11 Schematic diagram of the middle CC section;

[0050] Fig.15 for Fig.11 Schematic diagram of the EE section.

[0051] Description of main reference numerals:

[0052] 201. Strip foundation of original structure; 202. Foundation wall of original structure; 203. Concrete pouring; 204. Wall reinforcement; 205. Reinforced reinforcement; 301. Newly added steel column; 302. Ground beam of original structure; 303. Horizontal wall; 401. Double channel steel; 402. Tension bolts; 501. Angle steel; 502. Roof panel; 601. Opening; 701. Steel beam; 901. First building; 902. Second building; 903. Third building; 91. Single-layer chord truss; 911. First chord; 912. Second chord; 913. Temporary supporting round rod; 92. Three-layer chord truss; 921. First-layer chord frame; 922. Second-layer chord truss; 923. Third-layer chord truss; 924. Vertical connecting chord; 925. Outer contour of masonry reinforcement wall. DETAILED DESCRIPTION

[0053] 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.

[0054] Embodiment 1:

[0055] 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 walls on the east and west sides, which are reinforced with reinforced concrete surface layers, and a new steel structure is used inside.

[0056] like Figures 1 to 15 As shown, the construction method for dismantling and renovating an old building structure using a permanent and temporary truss support of the present invention comprises the following steps:

[0057] Step S1: Strengthen the foundation of the main building. Step S1 specifically includes:

[0058] Step S11, symmetrical excavation and support of earthwork on both sides of the main building indoors and outdoors: synchronous excavation of indoor and outdoor, with a height difference of 600mm between indoors and outdoors. According to the requirements of the drawings, excavation is carried out to a depth of -4.6m, so the actual outdoor excavation depth is 4.0m. The space outside the outer wall is relatively open, so mechanical excavation is used. The foundation is expanded outward by 300mm, and the slope is 1:1.15: the space inside the outer wall is limited, so manual excavation is used, and the foundation is expanded outward by 300mm, and the slope is 1:1.

[0059] Step S12: After the excavation of all areas is completed, the original structural strip foundation 201 of the retained outer longitudinal walls and the transverse walls of the first, second and third buildings on the east and west sides of the underground is enlarged and reinforced, and new steel columns are constructed on one side of each retained transverse wall. 100-thick C40 fine stone concrete is poured 203 from the elevation of -3.5 meters (for indoor transverse walls, the elevations are -3.3 and -3.4) to the outdoor ground elevation, and C30 commercial concrete is poured below the elevation of -3.5 meters (for indoor transverse walls, the elevations are -3.3 and -3.4). The total length of the newly added steel column 301 in this embodiment is 3.5 meters (each weighs 0.34 tons), and it is installed from the top of the concrete foundation of the original structure at an elevation of -4.1 to 200 mm below the lowest point of the original structure ground beam 302, that is, -4.1 meters to -0.8 meters. A special tool (wall saw) is used to cut the horizontal wall 303 vertically, and then the newly added steel column is manually transported from the adjacent window to the location, and placed obliquely into the incision, and finally the installation and fixation are completed. Figure 3 shown.

[0060] Step S13: After all the above work is completed, the earthwork is compacted and backfilled in layers.

[0061] Step S2: reinforcing the ground wall of the main building, specifically comprising:

[0062] Step S21, reinforce the vertical wall 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.

[0063] Step S22, cutting the horizontal wall along the vertical direction at the installation position of the newly added steel columns on each floor of different buildings and installing the reinforcement structure, the reinforcement structure is double channel steel 401, and the double channel steel 401 on both sides of the wall is fixed by tension bolts 402.

[0064] Step S23: Install a new steel column 301 at the end of the retained transverse wall, and set a steel beam 701 (such as Figure 8As shown by the arrow in the middle, some of the newly added steel columns 301 and steel beams 701 will be used as temporary supports during the demolition process and do not need to be demolished later. When the newly added steel column 301 is installed, the reinforcement structure at the corresponding position of the newly added steel column will be temporarily removed, but the reinforcement structure of the adjacent axis shall not be removed at the same time. After the construction of the newly added steel column is completed, the reinforcement structure will be restored immediately.

[0065] Furthermore, when constructing the newly added steel column 301, first cut the wall below the ground beam 302 where the newly added steel column is installed, and do not cut the ground beam. The ground beam supports the upper structure wall to meet the force requirements. Perform vertical cutting of the horizontal wall where the steel column is installed below the ground beam 302, manually transport the newly added steel column from the adjacent window to the location, place it obliquely in the cutout, and install and fix it. After the installation is completed, the newly added steel column 301 is vertically set in the cutout, the top of the newly added steel column 301 is 200mm away from the lowest point of the ground beam 302, and the bottom of the newly added steel column 301 is fixedly connected to the original structure ground beam through a mechanical anchor bolt. The newly added steel column 301 is installed in sections, the underground part is one section, the first floor of the above-ground part is one section, the second floor is two sections, the first to third floors of the third floor are one section, and the fourth to fifth floors are one section. The steel beam 701 is installed in each section as one, and the newly added steel column and steel beam are installed by a truck crane.

[0066] The cutting method is: 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 hole to the first floor, and then back to the roof. After installation, the brick 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 demolished, and reinforced double-channel steel is installed.

[0067] 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.

[0068] Step S3, dismantle and reinforce the truss support system of the main building in different areas and floors. The main building is dismantled and reinforced in different areas and floors. The load-bearing walls of the indoor area of ​​the main building are dismantled layer by layer and section by section in the order of top-down, south-to-north, first horizontal and then vertical components. The brick-concrete structure walls on the east and west sides are retained as a whole. As the walls are dismantled layer by layer, the reinforced truss support system is installed layer by layer from top to bottom. It specifically includes the following steps:

[0069] Step S31, divide the different buildings of the main building into areas, where the main building includes a first building 901, a second building 902 and a third building 903 which are connected in sequence from south to north, the first building 901 has three floors, the second building 902 has four floors, and the third building 903 has five floors. The first building 901 is divided into axes 1 to 6 from south to north, the second building 902 is divided into axes 7 to 12 from south to north, and the third building 903 is divided into axes 13 to 18 from south to north.

[0070] Step S32: Determine the demolition sequence of different floors of different buildings and the installation sequence of reinforcement trusses according to the construction drawings;

[0071] Step S33: Remove the load-bearing walls of the indoor shadow area of ​​the main building layer by layer and section by section from south to north (such as Fig. 9 As each layer is dismantled, reinforcement trusses are installed layer by layer from top to bottom.

[0072] Specifically, in step S32, according to the construction drawings, the demolition sequence of different floors of different buildings and the installation sequence of reinforcement trusses are determined, including:

[0073] Step S321, demolish the 1st to 6th axis of the top floor of the first building and the 1st to 3rd axis of the second top floor. The top floor and the second top floor of the first building 901 are demolished with large long-arm hydraulic pliers. The walls required to be retained in the drawings are not demolished. The demolition range of the third floor: the elevation of the 1st to 6th axis is above 6.35m, including the 6th axis; the demolition range of the second floor: the elevation of the 1st to 3rd axis is above 3.15m, excluding the 3rd axis. Fig. 10A shown.

[0074] Step S322: Construction of the first reinforcement truss on the top floor of the first building. Fig. 10B shown.

[0075] Step S323: partial demolition of the original structure of the first floor and the second floor of the first building. The original structure of the first floor and the second floor of the first building is demolished using short-arm hydraulic shears (such as Fig. 10C The demolition scope of the second floor is above the elevation of 3.15m from the 3rd to the 5th axis, excluding the 5th axis. The demolition scope of the first floor is above the elevation of -0.6m from the 1st to the 5th axis, excluding the 5th axis.

[0076] Step S324: The top floor and the second top floor of the second building 902 are removed from the 6th to 10th axis area. Fig. 10D Diagonal filled area), the fourth-floor demolition scope: the 6th to 10th axis elevation is above 6.35m, excluding the 10th axis; the third-floor demolition scope: the 6th to 10th axis elevation is above 3.15m, excluding the 10th axis.

[0077] Step S325: Construction of the second truss on the top floor of the first building and the first truss on the top floor of the second building. Fig.10E shown.

[0078] Step S326: The remaining area of ​​the first building, the first floor of the second building, and the partial original structure of the second floor are demolished. Fig.10F Middle oblique line filling area), second floor demolition scope: 5th to 10th axis elevation above 6.35m, excluding 10th axis; first floor demolition scope: 5th to 10th axis elevation above -0.6m, excluding 10th axis.

[0079] Step S327: Construction of the first reinforcement truss at the third floor of the second building. Figure 10G shown.

[0080] Step S328: demolish the top and second top floors of the northern half of the second building, and the top and second top floors of the third building (such as Fig. 10H The middle oblique line filling area), the five-story demolition scope: the 12th-15th axis elevation is above 12.75m, excluding the 15th axis; the four-story demolition scope: the 10th-15th axis elevation is above 9.55m, excluding the 15th axis; the three-story demolition scope: the 10th-12th axis elevation is above 5.35m, including the 11th axis.

[0081] Step S329: Construction of the second truss on the top floor of the second building and the first truss on the fourth floor of the third building. Fig.10I shown.

[0082] Step S330: demolish the remaining area of ​​the second building and the original structure of the first to third floors of the southern half of the third building (such as Fig.10J (the area filled with the middle oblique line): the third-floor demolition scope: the 11th to 15th axis elevation is above 6.35m, excluding the 15th axis; the second-floor demolition scope: the 10th to 15th axis elevation is above 3.15m, excluding the 15th axis; the first-floor demolition scope: the 12th to 15th axis elevation is above -0.6m, excluding the 15th axis.

[0083] Step S331: The original structure of the top floor and the second top floor of the northern half of the third building is removed (such as Figure 10K (the area filled with middle oblique lines): the fifth-floor demolition scope: the 15th-18th axis line elevation is above 12.75m, including the 18th axis line; the fourth-floor demolition scope: the 15th-17th axis line elevation is above 9.55m, including the 17th axis line; the 17th-18th axis line elevation is above 8.55m, including the 18th axis line.

[0084] Step S332: Install the second reinforcement truss at the fourth floor of the third building. Fig.10L shown.

[0085] Step S333: dismantle the remaining original structure of the third building (such as Figure 10M Medium diagonal fill area).

[0086] Step S334: The second reinforcement truss is installed on the third floor of the third building, the wall is removed, and a reinforcement truss support system is formed. Fig.10N As shown in Figure 11.

[0087] Specifically, the reinforcement truss of the first building 901 is a single-layer chord truss 91, and two single-layer chord trusses are symmetrically arranged on the north and south sides of the top floor of the first building, respectively. The single-layer chord truss includes two groups of first chords 911 and second chords 912 arranged parallel to the cross wall, and a plurality of temporary supporting round rods 913, wherein the first chord 911 is located at both ends of the second chord 912, and the outer ends of the first chord 911 are respectively fixedly connected to the newly added steel columns 301, and a temporary supporting round rod 913 is arranged between each group of two parallel first chords 911 and two parallel second chords 912, and the ends of the plurality of temporary supporting round rods on the outer sides of both ends of the second chord 912 are fixedly connected to the newly added steel columns 301.

[0088] Specifically, the reinforcement trusses of the second building 902 and the third building 903 are three-layer chord trusses 92. Two groups of three-layer chord trusses 92 are respectively arranged on the north and south sides of the second building 902 / the third building 903. The three-layer chord trusses 92 include a first-layer chord frame 921, a second-layer chord truss 922, a third-layer chord truss 923, a vertical connection chord 924, and a plurality of temporary support round rods 913. Among them, the first-layer chord frame 921, the second-layer chord truss 922, the ends of the third-layer chord truss 923 and the ends of the plurality of temporary support round rods 913 are fixedly connected to the newly added steel columns 301. Some of the newly added steel columns 301 and steel beams 701 are used as temporary supports during the demolition process and do not need to be demolished later. When the new steel structure of the main building is constructed later, the installed reinforcement truss support system can be used to construct the indoor steel beam and column system.

[0089] Step S4: indoor earth excavation.

[0090] After the demolition of the inner wall, the excavation of the independent foundation of the main building steel structure was carried out. The north and south gable areas were excavated to a depth of -4.6m according to the requirements of the drawings, and the outdoor slope was sloped according to a slope coefficient of 1:0.7. Since there is a 2-meter-deep pipe well indoors, the actual excavation depth indoors is 2.6m, and the slope is sloped according to a slope coefficient of 1:0.5.

[0091] Step S5: Indoor independent foundation construction and earth backfilling.

[0092] Step S6, construction of new steel structure of the main building: using the middle area of ​​each building as a vertical transportation hole, installing new steel columns, steel beams, corrugated steel plates layer by layer from bottom to top, and pouring concrete.

[0093] The newly built steel structure needs to be installed in sections according to the needs of temporary support. The newly added steel columns are divided into many sections. The upper supporting beams and columns are installed first, and the lower new beam-column system is installed after the cross partition wall is removed.

[0094] During the construction of the new steel structure of the main building, only the temporary supporting round rod 913 in the reinforced truss support system was removed. Based on retaining the newly installed steel columns and steel beams at the ends of the transverse walls and the reinforced truss support system after the temporary supporting round rods were removed, the indoor steel beam-column system was constructed layer by layer from the first floor upwards to form an overall steel frame structure, and viscous dampers were installed to enhance the seismic performance of the structure.

[0095] The structural system after transformation is:

[0096] 1. Vertical structural system:

[0097] (1) Retain the deadweight of the wall and transfer it to the foundation through the masonry itself;

[0098] (2) Retain the load of the cast-in-place floor slab and transfer it to the foundation through the steel structure;

[0099] (3) The load of the newly built part is transmitted to the foundation through the steel structure.

[0100] 2. Lateral force resisting structural system:

[0101] (1) A double lateral force resistance system is formed by reinforced concrete walls + steel frames;

[0102] (2) When moderate and large earthquakes occur, the damper provides energy dissipation and shock absorption, reducing the seismic response.

[0103] Although the 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 the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for dismantling and renovating an old building structure using a combination of permanent and temporary trusses, characterized in that: The old building structure 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 different building bodies arranged in a stepped manner. The old building structure demolition and reconstruction construction method includes the following steps: S1. Strengthen the foundation of the main building; S2. Strengthen the ground walls of the main building; S3: Dismantle and reinforce the truss support system of the main building in different areas and floors; S4, indoor earth excavation; S5. Indoor independent foundation construction and earth backfilling; S6. Construction of new steel structure of main building; When constructing new steel columns, first cut the wall below the ground beam where the new steel columns are to be installed, and then construct the new steel columns below the ground beam; Among them, in step S2, the ground wall reinforcement of the main building includes: S21. Strengthen the vertical walls above the outdoor ground of the main building 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; S22, cutting the horizontal wall along the vertical direction at the newly added steel column installation positions on each floor of different buildings and installing the reinforcement structure, wherein a set of reinforcement structures is immediately installed after each horizontal wall cutting is completed; S23. Install new steel columns and steel beams at the ends of the retained transverse walls, so that some of the new steel columns and steel beams can be used as temporary supports during the demolition process. When installing new steel columns, temporarily remove the reinforcement structure at the corresponding position of the new steel columns, but the reinforcement structures of adjacent axes shall not be removed at the same time. After the construction of the new steel columns is completed, immediately restore the reinforcement structure; Among them, in step S3, the main building is demolished and reinforced by area and floor, and the truss support system is constructed in accordance with the order of top-down, south-to-north, first horizontal and then vertical components. The indoor area load-bearing walls of the main building are demolished layer by layer and section by section, and the brick-concrete structure walls on the east and west sides are retained as a whole. As the layers are demolished layer by layer, the reinforced truss support system is installed layer by layer from top to bottom; wherein, the reinforced truss of the first building is a single-layer chord truss, and two single-layer chord trusses are symmetrically arranged on the north and south sides of the top floor of the first building, and the reinforced trusses of the second and third buildings are both three-layer chord trusses, and two three-layer chord trusses are arranged on the north and south sides of the second building / third building respectively; Among them, in step S6, the construction of the new steel structure of the main building includes: when constructing the new steel structure of the main building, only the temporary supporting round bars in the reinforced truss support system are removed, based on retaining the newly installed steel columns and steel beams at the ends of the transverse walls and the reinforced truss support system after the temporary supporting round bars are removed, the indoor steel beam-column system is constructed layer by layer from the first floor upwards to form an overall steel frame structure.

2. The method for dismantling and renovating an old building structure by using a combination of permanent and temporary trusses as claimed in claim 1 is characterized in that: In step S1, the main building foundation is reinforced, including: S11. Symmetrical excavation and support of earthwork on both sides of the interior and exterior of the main building; S12. After the excavation of all areas is completed, the strip foundations of the retained outer walls on the east and west sides of the underground are expanded and reinforced, the retained transverse wall part and the retained outer wall form a T-shaped wall, the wall is statically cut on one side of the retained transverse wall part, and additional steel columns are constructed; S13. Backfilling.

3. The method for dismantling and renovating an old building structure by using a combination of permanent and temporary truss supports according to claim 1 is characterized in that: In step S3, the main building is dismantled and reinforced by the truss support system in different areas and floors. The load-bearing walls of the indoor area of ​​the main building are dismantled layer by layer and section by section in the order of top to bottom, from south to north, first horizontal and then vertical components. The brick-concrete structure walls on the east and west sides are retained as a whole. As the walls are dismantled layer by layer, the reinforced truss support system is installed layer by layer from top to bottom, including: S31. Divide different buildings of the main building into regions, wherein the main building includes a first building, a second building, and a third building which are sequentially connected from south to north. The first building has three floors, the second building has four floors, and the third building has five floors. The first building is divided into axes 1 to 6 from south to north, the second building is divided into axes 7 to 12 from south to north, and the third building is divided into axes 13 to 18 from south to north. S32. Determine the demolition sequence of different floors of different buildings and the installation sequence of reinforcement trusses according to the construction drawings; S33. Gradually dismantle the walls from south to north and simultaneously install a reinforced truss support system.

4. The method for dismantling and renovating an old building structure by using a combination of permanent and temporary truss supports according to claim 3 is characterized in that: Step S32, determining the demolition sequence of different floors of different buildings and the installation sequence of reinforcement trusses according to the construction drawings, includes: S321, demolition of the 1st to 6th axis of the top floor of the first building and the 1st to 3rd axis of the second top floor; S322, construction of the first reinforcement truss on the top floor of the first building; S323, partial demolition of the original structure of the first floor and second floor of the first building; S324, demolition of the 6th to 10th axis area on the top floor and the second top floor of the second building; S325, construction of the second reinforcement truss on the top floor of the first building and the first reinforcement truss on the top floor of the second building; S326: demolition of the remaining area of ​​the first building, the first floor of the second building, and part of the original structure of the second floor; S327, construction of the first reinforcement truss at the third floor of the second building; S328, demolition of the top and second top floors of the northern half of the second building, and the top and second top floors of the third building; S329, construction of the second reinforcement truss on the top floor of the second building and the first reinforcement truss on the fourth floor of the third building; S330, the remaining area of ​​the second building, and the original structures from the first to the third floors of the southern half of the third building were demolished; S331, the original structure of the top floor and the second top floor of the northern half of the third building were demolished; S332, installation of the second reinforcement truss at the fourth floor of the third building; S333, the remaining original structure of the third building was demolished; S334. The second reinforcement truss on the third floor of the third building was installed, the wall was demolished, and a reinforcement truss support system was formed.

5. The method for dismantling and renovating an old building structure by using a combination of permanent and temporary truss supports according to claim 4 is characterized in that: The single-layer chord truss includes two groups of first chords, second chords and multiple temporary supporting round rods arranged parallel to the cross wall, the first chord is located at both ends of the second chord, the outer ends of the first chord are respectively fixedly connected to the newly added steel columns, and the ends of the temporary supporting round rods located on the outside are fixedly connected to the newly added steel columns; the three-layer chord truss includes a first-layer chord frame, a second-layer chord truss, a third-layer chord truss, a vertical connecting chord and multiple temporary supporting round rods, wherein the first-layer chord frame, the second-layer chord truss, the two ends of the third-layer chord truss and the ends of the temporary supporting round rods located on the outside are fixedly connected to the newly added steel columns.

6. The method for dismantling and renovating an old building structure using a combination of permanent and temporary truss supports according to claim 5 is characterized in that: During the construction of new steel columns, the original walls of each floor are cut with a rope saw. The rope saw is installed on the roof, and 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 brick wall is cut. Each part is cut from the first floor to the top floor at one time. After each cutting is completed, the corresponding wall is removed by shaving and chiseling, and the reinforcement structure is installed.

7. The method for dismantling and renovating an old building structure using a combination of permanent and temporary truss supports according to claim 6 is characterized in that: Install new steel columns and steel beams at the ends of the retained transverse walls, including: The underground part of the newly added steel columns connected to the retained cross walls is one section, the first building on the ground is one section, the second building is two sections, the first to third floors of the third building are one section, and the fourth to fifth floors are one section. The newly added steel beams are installed in each section, and the newly added steel columns and steel beams are installed with truck cranes.

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