Joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab and construction method thereof

Abstract

A joint between the top of a concrete-filled steel tubular column and a sandwich concrete composite slab and a construction method. The joint includes a concrete-filled steel tubular column, a sandwich concrete composite slab and a connecting steel plate. When using the connection method of combining a steel plate and a stud, it also includes a supporting angle steel, a pre-embedded bolt, a pre-welded screw rod and a stud. When using the connection method of combining a flange plate and high-strength bolts, it also includes a flange plate and high-strength bolts. The method is as follows: When using the connection method of combining a steel plate and a stud, fabricate the concrete-filled steel tubular column, the sandwich concrete composite slab and the supporting angle steel, install the concrete-filled steel tubular column in place, install the supporting angle steel, tighten the nuts of the pre-embedded bolt and the pre-welded screw rod, hoist the sandwich concrete composite slab in place, and pour concrete into the reserved holes for the studs. When using the connection method of combining a flange plate and high-strength bolts, install the concrete-filled steel tubular column in place, hoist the sandwich concrete composite slab in place, install the high-strength bolts and tighten the nuts, and pour concrete into the reserved holes for the bolts.

Description

Technical Field

[0001] The present invention belongs to the technical field of construction engineering, and particularly relates to a joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab and a construction method therefor. Background Art

[0002] A column-slab structure is a building structure with a load-bearing system composed of columns and floor slabs. It is a special case of a frame structure, generally mainly made of reinforced concrete materials. Since there is no beam under the indoor floor slab of the slab-column structure, it is convenient for the layout of mechanical and electrical pipelines, can reduce the storey height of the building, and has the advantages of smooth and simple space and flexible plane layout. The slab-column structure is suitable for multi-storey factories, warehouses, and the halls of public buildings, and can also be used for office buildings and residences, etc.

[0003] At present, the construction technology of the slab-column structure is mainly on-site wet operation. The in-situ construction not only causes serious environmental pollution, noise pollution and other problems, but also most of the operations are carried out manually on the construction site, resulting in low labor efficiency and long construction period. With the development of the economy, the in-situ construction means can no longer meet people's requirements for the quality of life and housing quality. The prefabricated structure has changed the consumption of resources and the impact on the environment of the traditional building method, and has outstanding advantages in construction, quality and other aspects. The prefabricated structure is produced through standardized production in the factory, which greatly reduces the on-site in-situ operation and significantly improves the labor productivity. The error of the prefabricated building reaches the millimeter level, and the components are produced in the factory, and the quality is greatly improved. In the building structure, the commonly used concrete columns and concrete slabs, steel columns and concrete slab structures require the columns to have good seismic performance, good ductility, strong bearing capacity, fast construction and other characteristics. Therefore, it is very necessary to research and develop a reasonable column-slab connection technology.

[0004] A concrete-filled steel tube column is a column structure formed by pouring concrete into a steel tube. Compared with the ordinary concrete column structure, it has the advantages of good seismic performance, light self-weight, good plasticity, fatigue resistance and impact resistance, and the steel tube provides a formwork for the concrete, which can effectively solve the problem of a large amount of formwork consumables.

[0005] A sandwich concrete composite slab is a new type of composite slab formed by connecting two steel plates and the concrete inside through shear connectors, and has the advantages of high bearing capacity, large stiffness, good ductility and fatigue resistance.

[0006] Therefore, for the slab-column structure of a concrete-filled steel tube column and a sandwich concrete composite slab, the respective structural characteristics can be fully utilized, thereby improving the lateral force resistance stiffness and seismic performance of the slab-column structure. However, the key lies in how to connect the top of the concrete-filled steel tube column and the sandwich concrete composite slab specifically. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab and a construction method thereof, which can ensure the stable connection between the top of the concrete-filled steel tube column and the sandwich concrete composite slab, while taking into account the construction efficiency and economic benefits, avoiding the problems of heavy and low-strength concrete floors and high costs of steel structures, reducing the structural self-weight, and improving the integrity, stability and seismic resistance of the slab-column structure.

[0008] To achieve the above object, the present invention adopts the following technical solutions: A joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab, which adopts a connection method of cooperating steel plates and stud bolts, includes a concrete-filled steel tube column, a sandwich concrete composite slab, a supporting angle steel, a connecting steel plate, embedded bolts, pre-welded screw rods and stud bolts; the connecting steel plate is horizontally welded and fixedly installed on the top of the concrete-filled steel tube column; the supporting angle steel is located between the connecting steel plate and the sandwich concrete composite slab, and the vertical limb of the supporting angle steel is fixedly connected to the concrete-filled steel tube column through the embedded bolts, and the horizontal limb of the supporting angle steel is fixedly connected to the connecting steel plate through the pre-welded screw rods; the number of the stud bolts is several, and several stud bolts are evenly distributed on the upper surface of the connecting steel plate, the stud bolts are vertically arranged, and the bottom end of the stud bolt is welded and fixedly connected to the upper surface of the connecting steel plate; a number of stud bolt reserved holes are formed in the sandwich concrete composite slab, and the number of the stud bolt reserved holes is the same as that of the stud bolts and the positions correspond one by one; post-cast concrete is poured in the stud bolt reserved holes.

[0009] The construction method of the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab includes the following steps:

[0010] Step 1: Fabricate the concrete-filled steel tube column, the sandwich concrete composite slab and the supporting angle steel;

[0011] ① When fabricating the concrete-filled steel tube column, first select the column body steel tube according to the design requirements, then process a specified number of reserved bolt holes at the set position on the top of the column body steel tube, then install the embedded bolts in each reserved bolt hole, and the screw rod of the embedded bolt protrudes from the column body steel tube, and then pour concrete into the column body steel tube until the concrete solidifies and forms the column body concrete; then select the connecting steel plate according to the design requirements, weld a specified number of pre-welded screw rods at the set position on the lower surface of the connecting steel plate, weld a specified number of stud bolts at the set position on the upper surface of the connecting steel plate, and then weld and fix the connecting steel plate welded with the pre-welded screw rods and the stud bolts to the top of the column body steel tube;

[0012] ② When fabricating the sandwich concrete composite slab, first select two steel plates according to the design requirements, and process a specified number of stud bolt reserved holes at the set positions on the two steel plates, then weld the embedded parts for enhancing the bonding effect with the concrete on the inner surfaces of the two steel plates, then complete the formwork support, and arrange the forming die for the stud bolt reserved holes in the formwork, and finally pour concrete into the formwork until the concrete solidifies and forms.

[0013] ③ When fabricating the supporting angle steel, first select the angle steel as the supporting angle steel according to the design dimensions, and then process a specified number of reserved bolt holes at the set positions on the horizontal and vertical limbs of the supporting angle steel.

[0014] Step 2: Install and position the fabricated concrete-filled steel tube column at the designated position.

[0015] Step 3: Deliver the fabricated supporting angle steel to the designated position at the top of the concrete-filled steel tube column, ensure that the pre-welded screw on the lower surface of the connecting steel plate accurately passes through the reserved bolt hole on the horizontal limb of the supporting angle steel, and at the same time ensure that the embedded bolt on the concrete-filled steel tube column accurately passes through the reserved bolt hole on the vertical limb of the supporting angle steel.

[0016] Step 4: Install and tighten the nuts on the pre-welded screws, and at the same time install and tighten the nuts on the embedded bolts until the supporting angle steel is fixed on the concrete-filled steel tube column.

[0017] Step 5: Hoist and lift the fabricated sandwich concrete composite slab above the top of the concrete-filled steel tube column, align the stud reserved holes on the sandwich concrete composite slab with the studs on the upper surface of the connecting steel plate, and then control the descent of the sandwich concrete composite slab until the sandwich concrete composite slab accurately lands on the upper surface of the connecting steel plate, and at the same time the studs enter the stud reserved holes.

[0018] Step 6: Pour concrete into the stud reserved holes until the concrete cures and forms the post-cast concrete, then the assembly is completed.

[0019] A joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab, which adopts a connection method combining a flange plate and high-strength bolts, includes a concrete-filled steel tube column, a sandwich concrete composite slab, a connecting steel plate, a flange plate and high-strength bolts; the connecting steel plate is horizontally welded and fixed on the top of the concrete-filled steel tube column; the flange plate is horizontally welded and fixed on the lower surface of the sandwich concrete composite slab; the sandwich concrete composite slab, the flange plate, the connecting steel plate and the concrete-filled steel tube column are distributed in sequence from top to bottom, bolt reserved holes are provided between the sandwich concrete composite slab, the flange plate and the connecting steel plate, high-strength bolts are inserted into the bolt reserved holes, and the sandwich concrete composite slab, the flange plate and the connecting steel plate are fixedly connected together through the high-strength bolts; post-cast concrete is poured into the bolt reserved holes.

[0020] The construction method of the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab includes the following steps:

[0021] Step 1: Fabricate the concrete-filled steel tube column and the sandwich concrete composite slab.

[0022] ①. When fabricating a concrete-filled steel tube column, first select the steel tube for the column body according to the design requirements, and then pour concrete into the interior of the column body steel tube until the concrete solidifies and forms the column body concrete. Then select the connecting steel plate according to the design requirements, process a specified number of bolt reserved holes at the set positions on the connecting steel plate, and then weld and fix the connecting steel plate to the top of the column body steel tube.

[0023] ②. When fabricating a sandwich concrete composite slab, first select two steel plates according to the design requirements, and process a specified number of bolt reserved holes at the set positions on the two steel plates. Then weld embedded parts for enhancing the bonding effect with the concrete on the inner surfaces of the two steel plates. Then select the flange plate according to the design dimensions, process a specified number of bolt reserved holes at the set positions on the flange plate, and then stack the flange plate on the lower surface of the bottom steel plate to ensure that the bolt reserved holes between the two are aligned. Then weld the flange plate to the bottom steel plate. After that, complete the formwork support, and arrange bolt reserved hole forming molds in the formwork. Finally, pour concrete into the formwork until the concrete solidifies and forms.

[0024] Step two: Install and position the fabricated concrete-filled steel tube column at the specified position.

[0025] Step three: Hoist and lift the fabricated sandwich concrete composite slab above the top of the concrete-filled steel tube column, align the bolt reserved holes on the sandwich concrete composite slab with the bolt reserved holes on the connecting steel plate, and then control the sandwich concrete composite slab to descend until it accurately lands on the upper surface of the connecting steel plate.

[0026] Step four: Install high-strength bolts in each bolt reserved hole and tighten the nuts.

[0027] Step five: Pour concrete into the bolt reserved holes until the concrete solidifies and forms the post-cast concrete, then the assembly is completed.

[0028] Advantages of the present invention:

[0029] For the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab and the construction method of the present invention, while ensuring the stable connection between the top of the concrete-filled steel tube column and the sandwich concrete composite slab, it can take into account the construction efficiency and economic benefits, avoid the problems of heavy and low-strength concrete floors and high costs of steel structures, reduce the structural self-weight, and improve the integrity, stability and seismic resistance of the slab-column structure. Description of the drawings

[0030] Figure 1 It is a structural schematic diagram of a joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab (adopting a connection method of cooperation between a steel plate and a stud) of the present invention.

[0031] Figure 2 For Figure 1Cross-sectional view A-A;

[0032] Figure 3 is Figure 1 Cross-sectional view B-B;

[0033] Figure 4 Structural schematic diagram of the sandwich concrete composite slab of the present invention (adopting the connection method of combining steel plates and stud bolts);

[0034] Figure 5 is Figure 4 Cross-sectional view C-C;

[0035] Figure 6 Structural schematic diagram of the joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab of the present invention (adopting the connection method of combining a flange plate and high-strength bolts);

[0036] Figure 7 is Figure 6 Cross-sectional view D-D;

[0037] Figure 8 is Figure 6 Cross-sectional view E-E;

[0038] Figure 9 is Figure 6 Cross-sectional view F-F (the steel tube of the column body adopts a square steel tube);

[0039] Figure 10 is Figure 6 Cross-sectional view F-F (the steel tube of the column body adopts a circular steel tube);

[0040] Figure 11 Structural schematic diagram of a sandwich concrete composite slab (adopting the connection method of combining a flange plate and high-strength bolts);

[0041] Figure 12 is Figure 12 Cross-sectional view G-G;

[0042] In the figure, 1 - concrete-filled steel tube column, 2 - stud bolt, 3 - steel tube of the column body, 4 - embedded bolt, 5 - post-cast concrete, 6 - sandwich concrete composite slab, 7 - connecting steel plate, 8 - supporting angle steel, 9 - pre-welded screw rod, 10 - reserved hole for stud bolt, 11 - concrete of the column body, 12 - high-strength bolt, 13 - flange plate, 14 - reserved hole for bolt. Specific implementation mode

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] As Figures 1 to 5As shown in the figure, a joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab adopts a connection method combining steel plates and stud bolts, and includes a concrete-filled steel tube column 1, a sandwich concrete composite slab 6, a supporting angle steel 8, a connecting steel plate 7, embedded bolts 4, pre-welded screw rods 9 and stud bolts 2; the connecting steel plate 7 is horizontally welded and fixedly installed at the top of the concrete-filled steel tube column 1; the supporting angle steel 8 is located between the connecting steel plate 7 and the sandwich concrete composite slab 6, and the vertical limb of the supporting angle steel 8 is fixedly connected to the concrete-filled steel tube column 1 through the embedded bolts 4, and the horizontal limb of the supporting angle steel 8 is fixedly connected to the connecting steel plate 7 through the pre-welded screw rods 9; the number of the stud bolts 2 is several, and several stud bolts 2 are evenly distributed on the upper surface of the connecting steel plate 7, the stud bolts 2 are vertically arranged, and the bottom end of the stud bolt 2 is welded and fixedly connected to the upper surface of the connecting steel plate 7; a number of stud bolt reserved holes 10 are formed in the sandwich concrete composite slab 6, and the number of the stud bolt reserved holes 10 is the same as that of the stud bolts 2 and the positions correspond one by one; post-cast concrete 5 is poured in the stud bolt reserved holes 10.

[0045] The construction method of the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab includes the following steps:

[0046] Step 1: Fabricate the concrete-filled steel tube column 1, the sandwich concrete composite slab 6 and the supporting angle steel 8;

[0047] ① When fabricating the concrete-filled steel tube column 1, first select the column steel tube 3 according to the design requirements, then process a specified number of reserved bolt holes at the set position at the top of the column steel tube 3, then install the embedded bolts 4 in each reserved bolt hole, and the screw rods of the embedded bolts 4 protrude from the column steel tube 3, and then pour concrete into the column steel tube 3 until the concrete solidifies and forms the column body concrete 11; then select the connecting steel plate 7 according to the design requirements, weld a specified number of pre-welded screw rods 9 at the set position on the lower surface of the connecting steel plate 7, weld a specified number of stud bolts 2 at the set position on the upper surface of the connecting steel plate 7, and then weld and fix the connecting steel plate 7 welded with the pre-welded screw rods 9 and the stud bolts 2 to the top of the column steel tube 3.

[0048] ② When fabricating the sandwich concrete composite slab 2, first select two steel plates according to the design requirements, and process a specified number of stud bolt reserved holes 10 at the set positions on the two steel plates, then weld embedded parts for enhancing the bonding effect with the concrete on the inner surfaces of the two steel plates, then complete formwork support, and arrange a forming mold for the stud bolt reserved holes 10 in the formwork, and finally pour concrete in the formwork until the concrete solidifies and forms.

[0049] ③ When fabricating the supporting angle steel 8, first select a right-angle steel as the supporting angle steel 8 according to the design dimensions, and then process a specified number of reserved bolt holes at the set positions on the horizontal limb and the vertical limb of the supporting angle steel 8.

[0050] Step 2: Install and position the fabricated concrete-filled steel tube column 1 at the designated location;

[0051] Step 3: Deliver the fabricated supporting angle steel 8 to the designated position at the top of the concrete-filled steel tube column 1, ensuring that the pre-welded screw 9 on the lower surface of the connecting steel plate 7 accurately passes through the reserved bolt holes on the horizontal limb of the supporting angle steel 8, and at the same time ensuring that the embedded bolt 4 on the concrete-filled steel tube column 1 accurately passes through the reserved bolt holes on the vertical limb of the supporting angle steel 8;

[0052] Step 4: Install and tighten nuts on the pre-welded screw 9, and at the same time install and tighten nuts on the embedded bolt 4 until the supporting angle steel 8 is fixed on the concrete-filled steel tube column 1;

[0053] Step 5: Hoist and lift the fabricated sandwich concrete composite slab 2 above the top of the concrete-filled steel tube column 1, align the stud reserved holes 10 on the sandwich concrete composite slab 2 with the studs 2 on the upper surface of the connecting steel plate 7, and then control the descent of the sandwich concrete composite slab 2 until the sandwich concrete composite slab 2 accurately lands on the upper surface of the connecting steel plate 7, and at the same time the studs 2 enter the stud reserved holes 10;

[0054] Step 6: Pour concrete into the stud reserved holes 10 until the concrete cures and forms the post-cast concrete 5, then the assembly is completed.

[0055] As Figures 6 to 12 shown, a joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab, adopting a connection method of flange plate and high-strength bolts, includes a concrete-filled steel tube column 1, a sandwich concrete composite slab 6, a connecting steel plate 7, a flange plate 13 and high-strength bolts 12; the connecting steel plate 7 is horizontally welded and fixed on the top of the concrete-filled steel tube column 1; the flange plate 13 is horizontally welded and fixed on the lower surface of the sandwich concrete composite slab 6; the sandwich concrete composite slab 6, the flange plate 13, the connecting steel plate 7 and the concrete-filled steel tube column 1 are distributed in sequence from top to bottom, bolt reserved holes 14 are provided between the sandwich concrete composite slab 6, the flange plate 13 and the connecting steel plate 7, high-strength bolts 12 are inserted into the bolt reserved holes 14, and the sandwich concrete composite slab 6, the flange plate 13 and the connecting steel plate 7 are fixedly connected together through the high-strength bolts 12; post-cast concrete 5 is poured into the bolt reserved holes 14.

[0056] The construction method of the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab includes the following steps:

[0057] Step 1: Fabricate the concrete-filled steel tube column 1 and the sandwich concrete composite slab 6;

[0058] ①. When fabricating the concrete-filled steel tube column 1, first select the column steel tube 3 according to the design requirements, and then pour concrete into the interior of the column steel tube 3 until the concrete solidifies and forms the column body concrete 11. Then select the connecting steel plate 7 according to the design requirements, process a specified number of bolt reserved holes 14 at the set positions on the connecting steel plate 7, and then weld and fix the connecting steel plate 7 to the top of the column steel tube 3.

[0059] ②. When fabricating the sandwich concrete composite slab 2, first select two steel plates according to the design requirements, and process a specified number of bolt reserved holes 14 at the set positions on the two steel plates. Then weld the embedded parts for enhancing the bonding effect with the concrete on the inner surfaces of the two steel plates. Then select the flange plate 13 according to the design dimensions, process a specified number of bolt reserved holes 14 at the set positions on the flange plate 13, and then stack the flange plate 13 on the lower surface of the bottom steel plate to ensure that the bolt reserved holes 14 between the two are aligned, and then weld the flange plate 13 to the bottom steel plate. Then complete the formwork support, and arrange the forming die for the bolt reserved holes 14 in the formwork. Finally, pour concrete into the formwork until the concrete solidifies and forms.

[0060] Step two: Install and position the fabricated concrete-filled steel tube column 1 at the specified position.

[0061] Step three: Hoist and lift the fabricated sandwich concrete composite slab 2 above the top of the concrete-filled steel tube column 1, align the bolt reserved holes 14 on the sandwich concrete composite slab 2 with the bolt reserved holes 14 on the connecting steel plate 7, and then control the sandwich concrete composite slab 2 to descend until the sandwich concrete composite slab 2 accurately lands on the upper surface of the connecting steel plate 7.

[0062] Step four: Install high-strength bolts 12 in each bolt reserved hole 14 and tighten the nuts.

[0063] Step five: Pour concrete into the bolt reserved holes 14 until the concrete solidifies and forms the post-cast concrete 5, and then the assembly is completed.

[0064] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. Any equivalent implementation or modification without departing from the present invention is included in the patent scope of this case.

Claims

1. A joint between the top of a concrete-filled steel tube column and a sandwich concrete composite slab, characterized in that: It adopts a connection method of combining steel plates and stud bolts, and includes a concrete-filled steel tube column, a sandwich concrete composite slab, a supporting angle steel, a connecting steel plate, embedded bolts, pre-welded screw rods and stud bolts; the connecting steel plate is horizontally welded and fixed on the top of the concrete-filled steel tube column; the supporting angle steel is located between the connecting steel plate and the concrete-filled steel tube column, and the vertical limb of the supporting angle steel is fixedly connected to the concrete-filled steel tube column through the embedded bolts, and the horizontal limb of the supporting angle steel is fixedly connected to the connecting steel plate through the pre-welded screw rods; the number of the stud bolts is several, and several stud bolts are evenly distributed on the upper surface of the connecting steel plate, the stud bolts are vertically arranged, and the bottom end of the stud bolt is welded and fixed to the upper surface of the connecting steel plate; several stud bolt reserved holes are opened on the sandwich concrete composite slab, and the number of the stud bolt reserved holes is the same as that of the stud bolts and the positions correspond one by one; post-cast concrete is poured in the stud bolt reserved holes.

2. The construction method of the joint between the top of the concrete-filled steel tube column and the sandwich concrete composite slab according to claim 1, characterized in that it includes the following steps: Step 1: Fabricate the concrete-filled steel tube column, the sandwich concrete composite slab and the supporting angle steel; ①. When fabricating the concrete-filled steel tube column, first select the column steel tube according to the design requirements, then process a specified number of reserved bolt holes at the set position on the top of the column steel tube, then install the embedded bolts in each reserved bolt hole, and the screw rod of the embedded bolt exposes outside the column steel tube, and then pour concrete into the column steel tube until the concrete solidifies and forms the column body concrete; then select the connecting steel plate according to the design requirements, weld a specified number of pre-welded screw rods at the set position on the lower surface of the connecting steel plate, weld a specified number of stud bolts at the set position on the upper surface of the connecting steel plate, and then weld and fix the connecting steel plate welded with the pre-welded screw rods and stud bolts to the top of the column steel tube; ②. When fabricating the sandwich concrete composite slab, first select two steel plates according to the design requirements, and process a specified number of stud bolt reserved holes at the set positions on the two steel plates, then weld the embedded parts for enhancing the bonding effect with the concrete on the inner surfaces of the two steel plates, then complete the formwork support, and arrange the forming molds for the stud bolt reserved holes in the formwork, and finally pour concrete into the formwork until the concrete solidifies and forms; ③. When fabricating the supporting angle steel, first select the right-angle steel as the supporting angle steel according to the design dimensions, and then process a specified number of reserved bolt holes at the set positions on the horizontal limb and the vertical limb of the supporting angle steel; Step 2: Install and position the fabricated concrete-filled steel tube column at the designated position; Step 3: Send the fabricated supporting angle steel to the designated position at the top of the concrete-filled steel tube column, ensure that the pre-welded screw rods on the lower surface of the connecting steel plate accurately pass through the reserved bolt holes on the horizontal limb of the supporting angle steel, and at the same time ensure that the embedded bolts on the concrete-filled steel tube column accurately pass through the reserved bolt holes on the vertical limb of the supporting angle steel; Step 4: Install and tighten the nuts on the pre-welded screw rods, and at the same time install and tighten the nuts on the embedded bolts until the supporting angle steel is fixed on the concrete-filled steel tube column; Step 5: Hoist the fabricated sandwich concrete composite slab above the top of the concrete-filled steel tubular column, align the stud reserved holes on the sandwich concrete composite slab with the studs on the upper surface of the connecting steel plate, and then control the descent of the sandwich concrete composite slab until it accurately lands on the upper surface of the connecting steel plate, and at the same time, the studs enter the stud reserved holes; Step 6: Pour concrete into the stud reserved holes until the concrete cures and forms post-cast concrete, then the assembly is completed.

3. A joint between the top of a concrete-filled steel tubular column and a sandwich concrete composite slab Characterized in that: It adopts a connection method combining a flange plate and high-strength bolts, and includes a concrete-filled steel tubular column, a sandwich concrete composite slab, a connecting steel plate, a flange plate and high-strength bolts; the connecting steel plate is horizontally welded and fixed on the top of the concrete-filled steel tubular column; the flange plate is horizontally welded and fixed on the lower surface of the sandwich concrete composite slab; the sandwich concrete composite slab, the flange plate, the connecting steel plate and the concrete-filled steel tubular column are distributed in sequence from top to bottom. Bolt reserved holes are provided between the sandwich concrete composite slab, the flange plate and the connecting steel plate, and high-strength bolts are inserted into the bolt reserved holes. The sandwich concrete composite slab, the flange plate and the connecting steel plate are fixedly connected together by high-strength bolts; post-cast concrete is poured into the bolt reserved holes.

4. The construction method of the joint between the top of the concrete-filled steel tubular column and the sandwich concrete composite slab according to claim 3 Characterized in that It includes the following steps: Step 1: Fabricate the concrete-filled steel tubular column and the sandwich concrete composite slab; ①. When fabricating the concrete-filled steel tubular column, first select the column steel pipe according to the design requirements, and then pour concrete into the inner part of the column steel pipe until the concrete cures and forms the column body concrete; then select the connecting steel plate according to the design requirements, process a specified number of bolt reserved holes at the set positions on the connecting steel plate, and then weld and fix the connecting steel plate to the top of the column steel pipe; ②. When fabricating the sandwich concrete composite slab, first select two steel plates according to the design requirements, process a specified number of bolt reserved holes at the set positions on the two steel plates, and then weld embedded parts on the inner surfaces of the two steel plates for enhancing the bonding effect with the concrete; then select the flange plate according to the design dimensions, process a specified number of bolt reserved holes at the set positions on the flange plate, and then stack the flange plate on the lower surface of the bottom steel plate, ensure that the bolt reserved holes between the two are aligned, and then weld the flange plate to the bottom steel plate; then complete the formwork support, and arrange bolt reserved hole forming molds in the formwork, and finally pour concrete into the formwork until the concrete cures and forms; Step 2: Install and position the fabricated concrete-filled steel tubular column at the designated position; Step 3: Hoist the fabricated sandwich concrete composite slab above the top of the concrete-filled steel tubular column, align the bolt reserved holes on the sandwich concrete composite slab with the bolt reserved holes on the connecting steel plate, and then control the descent of the sandwich concrete composite slab until it accurately lands on the upper surface of the connecting steel plate; Step 4: Install high-strength bolts in each bolt reserved hole and tighten the nuts; Step Five: Pour concrete into the bolt reserved holes until the concrete cures and forms post-cast concrete, then the assembly is completed.

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