A construction method for steel tube concrete composite column

Abstract

The invention provides a construction method of steel tube concrete composite column, comprising the following steps: S1, in-depth design, including the following contents, 1) selecting a steel tube extension method, 2) selecting a beam-column connection method, 3) steel tube design, 4) selecting a composite column foot, S2, steel component processing, S3, composite column positioning plate and column foot installation, S4, composite column natural layer steel tube construction, S5, installation of capping steel tube, which solves the existing on-site hole drilling that only relies on design drawings, the steel bar worker cannot accurately judge the position of the steel bar on the steel tube column, easily causes misaligned holes and waste holes, the construction quality cannot be guaranteed, and the compressive and seismic performances are poor. It produces not only clear force transmission, simple structure, good integrity, safety and reliability, but also, in actual operation, this mode of hole drilling construction has a greatly guaranteed hole quality compared with on-site hole drilling, thereby ensuring the construction quality at the source and ensuring the beneficial effect of the accuracy of the hole drilling.

Description

Technical Field

[0001] The invention relates to the technical field of composite column construction, and in particular to a construction method of steel tube concrete composite column. Background Art

[0002] Composite steel tube concrete columns refer to columns composed of the steel tube concrete in the middle of the section and the reinforced concrete outside the steel tube, referred to as composite columns. According to the cross-sectional shape, they can be divided into rectangular and circular cross-sectional steel tube composite columns, with the circular cross-sectional being the most complex. The reason why it is called "composite" is that the steel tube concrete in the core area is actually overlapped with the reinforced concrete outside the steel tube to bear the load. Composite steel tube concrete columns are a construction process that includes multiple processes such as steel structure installation, steel bar binding, formwork support, concrete pouring, and maintenance.

[0003] Since drilling holes has a subtractive effect on the performance of steel tube composite columns, the appropriateness and accuracy of drilling holes are very important. When the beam reinforcement of the beam-column node passes through the steel tube in the construction of steel tube concrete composite column structure, only relying on the on-site drilling of the design drawings, the reinforcement workers cannot accurately judge the position of the reinforcement on the steel tube column, which can easily cause misplaced holes and waste holes, and the construction quality cannot be guaranteed. Therefore, it is very easy to cause misplaced holes. For example, if the drilling position is inaccurate, the drilling area is inaccurate, the drilling quality cannot be guaranteed, and the corresponding section loss rate is exceeded, that is, the section loss rate of no more than 50% specified in the "Technical Code for Reinforced Concrete Composite Column Structure" is exceeded. At the same time, after the on-site drilling construction of the steel tube concrete composite column structure, its compressive performance and seismic performance are poor. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a construction method for steel tube concrete composite columns, which solves the problem in the prior art that the on-site drilling only relies on the design drawings, the reinforcement workers cannot accurately judge the position of the reinforcement on the steel tube column, which easily causes misplaced holes and waste holes, and the construction quality cannot be guaranteed. Therefore, it is very easy to cause misplaced holes, such as inaccurate drilling positions and inaccurate drilling areas, and the drilling quality cannot be guaranteed, exceeding the corresponding section loss rate, that is, exceeding the section loss rate of no more than 50% stipulated in the "Technical Code for Reinforced Concrete Composite Column Structures". At the same time, the steel tube concrete composite column structure has poor compressive and seismic performance after on-site drilling construction.

[0005] According to a technical solution of the present invention, a construction method of a steel tube concrete composite column includes the following steps:

[0006] S1. In-depth design, including the following: 1) Select the steel pipe extension method. Select the appropriate type of steel pipe for extension according to the design drawings, and the reliability should be verified. 2) Select the beam-column connection method. The beam-column connection must be selected according to the structural characteristics of the design drawings and the building layout. The connection includes the connection between steel beams and composite columns and the connection between reinforced concrete beams and composite columns, and the reliability should be verified. 3) Steel pipe design. Select steel pipes with appropriate strength and length. Determine the openings on the steel pipes for passing steel bars according to the relative positions of the pre-installed steel pipes on the floors. 4) Select the column foot of the composite column. According to the different foundation forms, the corresponding reliable and effective column foot forms should be adopted;

[0007] S2. Processing of steel components, including the following: 1) Production of steel pipes and accessories, production of steel pipes in accordance with the dimensions required by the design and detailed drawings, including reserved grooves at the joints of steel pipes, welding of cylindrical head bolts on the outside of steel pipes, popping out the reference axis on the steel pipes for positioning the constructed steel pipe superimposed columns, and opening holes in the reserved positions for the longitudinal reinforcement of the upper beams of the steel pipes, production of steel component accessories in accordance with the dimensions required by the design and detailed drawings, including positioning plates, lining pipes, and reinforced ribs; 2) Pre-assembly of steel components, assembly of various steel components including positioning plates, column bases, natural steel pipe sections, and capping steel pipe sections in the processing plant;

[0008] S3. Installation of the composite column positioning plate and column foot. According to the design and detailed drawing requirements, multiple screws for fixing the positioning plate are fixed and tied on the corresponding steel mesh. Two layers of nuts are threaded on the screws. The lower layer of nuts are welded to the screws after leveling the positioning plate. The column foot is hoisted. The bottom plate of the column foot corresponds to the positioning plate. The screw passes through the bottom plate. After leveling the bottom plate of the column foot with the upper layer of nuts, the double nuts are tightened on the screws and welded to the screws.

[0009] S4. Construction of natural layer steel pipes for composite columns includes the following: 1) Hoisting of extended steel pipes, cleaning of the concrete at the mouth of the installed steel pipes, hoisting of the extended steel pipes to the operating surface, fixing of the tower crane steel cable to the top of the extended steel pipes, vertical hoisting to the air above the installed steel pipes, slowly placing them on the installed steel pipes, and roughly aligning them. The operator hangs a magnetic plumb bob on the top of the extended steel pipes to control the vertical deviation of the extended steel pipes, and uses a crowbar to make fine adjustments until they are fully aligned. The hooks are not removed during this process. 2) Installation of ear plates, spot welding them to the installed and extended steel pipes respectively, and then spot welding at the seams of the installed and extended steel pipes for preliminary fixation, and then removing the hooks. 3) Steel pipe welding: After installing the ear plates, use manual arc welding to weld the installed and extended steel pipes, and the welds are equal-strength groove butt joints. Welding seams, remove the ear plates after welding, 4) Tie column reinforcement, tie column longitudinal reinforcement and stirrups according to the requirements of the drawings, 5) Support column formwork, install the composite column formwork according to the special formwork construction plan, 6) Pour concrete in the steel pipe, the concrete in the pipe should be dropped from a high position without vibration, and the pipe should be closed after pouring, 7) Build concrete outside the steel pipe, and fine stone concrete should be used for the concrete outside the pipe, 8) Through the beam reinforcement, after the beam formwork construction is completed, the steel bars should be passed through the steel pipe according to the hole position, and then the steel bars should be connected, 9) Pour concrete at the beam-column joint, the strength grade of the beam-column joint is higher than that of the beam-slab concrete, and the joint is blocked with wire mesh. The concrete in the steel pipe in the core area should be poured first, and then the concrete outside the steel pipe in the core area should be poured, and finally the other beams and slabs should be poured;

[0010] S5. Install the capping steel pipe, install the prefabricated capping steel pipe, and insert the core column steel bars into the reserved holes for the longitudinal bars, and then pour the concrete in the steel pipe.

[0011] The technical principle of the present invention is: on the basis of the design drawings, the factors that may affect the opening of the holes on the construction site are predicted and taken into account in the in-depth design. The more factors considered and the more in line with the on-site construction conditions, the better the success rate of the pre-opening can be controlled, so that it not only meets the design requirements but also paves the way for the next construction process. Through the in-depth design of the steel pipe extension method, the beam-column connection method, the steel pipe design, the steel pipe opening and the selection of the composite column foot, the steel tube concrete composite column obtained by the construction method according to this construction method not only has clear force transmission, simple structure, good integrity, safety and reliability, but also has a computer simulation of the site with the in-depth design. , calculate a solution that is more suitable for the site, and the cross-section opening loss rate can be guaranteed in the design stage. Pre-opening holes on the steel pipe can predict the penetration points of the steel bars on the steel pipe in advance. The corresponding opening dimensions have been designed before the holes are opened. There are corresponding design drawings as a basis for opening holes. It is easier to operate in an off-site environment, and there are professionals to perform on-site layout and cutting. In actual operation, this mode of opening construction has greatly guaranteed the quality of the holes compared to on-site opening, thereby ensuring the construction quality at the source, ensuring the accuracy of the opening, saving materials, simplifying the complex, and making the construction of steel tube concrete composite columns more convenient.

[0012] Compared with the prior art, the present invention has the following beneficial effects: through in-depth design of steel pipe extension methods, beam-column connection methods, steel pipe design, steel pipe openings and the selection of composite column foot, computer simulation of the site with in-depth design is performed to calculate a solution that is more suitable for the site, and the cross-sectional opening loss rate can be guaranteed in the design stage, which solves the existing on-site opening that only relies on design drawings. The steel bar workers cannot accurately judge the position of the steel bars on the steel pipe column, which easily causes misplaced holes and waste holes, and the construction quality cannot be guaranteed. Therefore, it is very easy to cause misplaced holes, such as inaccurate opening positions, inaccurate opening areas, and opening quality cannot be guaranteed. , exceeding the corresponding section loss rate, that is, exceeding the section loss rate of no more than 50% stipulated in the "Technical Code for Reinforced Concrete Composite Column Structure". At the same time, the technical problem of poor compressive and seismic performance of the steel tube concrete composite column structure after on-site hole construction has produced not only clear force transmission, simple structure, good integrity, safety and reliability, but also, in actual operation, this mode of hole construction has greatly guaranteed the quality of the holes compared with on-site hole drilling, thereby ensuring the construction quality at the source, ensuring the accuracy of the hole drilling, saving materials, simplifying the complex, and making the construction of steel tube concrete composite columns more convenient. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further described below in conjunction with embodiments.

[0014] A technical solution embodiment of the present invention provides a construction method for steel tube concrete composite columns, comprising the following steps:

[0015] S1. Deepening design, including the following: 1) Select the steel pipe extension method. According to the design drawings, select the appropriate type of steel pipe for extension, and it should be verified for reliability. The steel pipe extension should extend about 900-1100mm above the floor level to facilitate welding by welders. In actual operation, it is possible to make full use of the raw material size to reduce the scrap rate. At the same time, it is advisable to consider staggering the position of the column longitudinal reinforcement joint to determine the steel pipe extension position, thereby determining the pipe mouth elevation; 2) Select the beam-column connection method. The beam-column connection must be selected according to the structural characteristics of the design drawings and the building layout. It includes the connection between steel beams and composite columns and reinforced concrete beams. It is connected with the composite column and reliability calculation should be carried out. The connection between the steel beam and the composite column can be realized by welding the connecting web of the steel structure according to the practice of steel structure; 3) Steel pipe design: select steel pipes with appropriate strength and length. The length of the steel pipe is determined by the pipe mouth elevation of the constructed steel pipe and the elevation of the protruding floor of the pre-constructed steel pipe. The pipe mouth elevation of the constructed steel pipe is the same. Due to the different ways of connecting the steel pipes, the designed length of the steel pipe will also be different. The openings on the steel pipe for passing the steel bars are determined according to the relative positions of the pre-constructed steel pipes on the floors; 4) Selection of the base of the composite column: adopt corresponding reliable and effective base forms according to different foundation forms.

[0016] S2. Processing of steel components, including the following: 1) Fabrication of steel pipes and accessories, manufacturing steel pipes in accordance with the dimensions required by the design and detailed drawings, including reserving grooves at steel pipe joints, welding cylindrical head bolts on the outside of steel pipes, popping out reference axes on steel pipes for positioning the constructed steel pipe composite columns, and opening holes in the reserved positions for the longitudinal reinforcement of the steel pipe upper beams. Manufacturing of steel component accessories, including positioning plates, lining pipes, and reinforced ribs, in accordance with the dimensions required by the design and detailed drawings; 2) Pre-assembly of steel components, assembling various steel components in the processing plant, including positioning plates, column bases, natural steel pipe sections, and capping steel pipe sections.

[0017] S3. Installation of the positioning plate and column foot of the composite column. According to the design and detailed drawing requirements, multiple screws for fixing the positioning plate are fixed and tied on the corresponding steel mesh. Two layers of nuts are threaded on the screws. The lower layer of nuts are welded to the screws after leveling the positioning plate. The column foot is hoisted. The bottom plate of the column foot corresponds to the positioning plate. The screw passes through the bottom plate. After leveling the bottom plate of the column foot with the upper layer of nuts, the double nuts are tightened on the screws and welded to the screws. After pouring the foundation slab, the gap between the column foot and the foundation slab should be grouted for the second time. It is advisable to use high-efficiency non-shrinkage grouting material for pressure grouting. C40 non-shrinkage fine stone concrete or mortar can also be used. After reaching the strength, the external concrete pouring of the composite column can be carried out.

[0018] S4. Construction of natural layer steel pipes for composite columns includes the following contents: 1) Hoisting of extended steel pipes, cleaning the concrete at the mouth of the installed steel pipes, hoisting the extended steel pipes to the operating surface, fixing the tower crane steel cable on the top of the extended steel pipes, hoisting vertically to the air above the installed steel pipes, slowly placing them on the installed steel pipes, and roughly aligning them. The operator hangs a magnetic line plumb on the top of the extended steel pipes to control the vertical deviation of the extended steel pipes, and uses a crowbar to make fine adjustments until they are fully aligned. The hooks are not removed during this period; 2) Installing ear plates, spot welding them to the installed and extended steel pipes respectively, and then spot welding the pipe seams of the installed and extended steel pipes for preliminary fixation, and then removing the hooks; 3) Steel pipe welding, after installing the ear plates, use manual arc welding to weld the installed and extended steel pipes, and the welds are equal-strength groove butt welds. After welding, remove the ear plates; 4) Binding column reinforcement, according to the requirements of the drawings, bind the column longitudinal reinforcement and stirrups, and the thickness of the column longitudinal reinforcement protective layer should not be less than 30mm. After the binding is completed, the water and electricity pipes can be installed; 5) Support the column formwork and install the composite column formwork according to the special formwork construction plan; 6) Pour the concrete inside the steel pipe. The concrete inside the pipe should be cast from a high position without vibration. Before pouring, a layer of cement mortar with a thickness of 100 to 200 mm and the same grade of concrete should be poured. The pouring elevation should be controlled during pouring and should not be higher than 150 mm below the bottom elevation of the opening. After pouring, the pipe should be closed; 7) Concrete outside the steel pipe should be constructed. Fine stone concrete should be used for the concrete outside the pipe. When pouring concrete outside, the pouring elevation should be controlled. High, should not be less than 150mm below the bottom elevation of the pre-opening hole. Since the steel bars outside the tube are dense, the vibration time should be increased to enhance the density of the concrete; 8) After the beam formwork is completed, the steel bars should be passed through the steel tube according to the hole position, and then the steel bars should be connected. In this process, additional stirrups should be inserted and tied at the beam-column nodes; 9) Casting concrete at the beam-column nodes. The strength grade of the beam-column nodes is higher than that of the beam-slab concrete. The nodes are blocked with wire mesh. The concrete inside the steel tube in the core area should be poured first, and then the concrete outside the steel tube in the core area should be poured, and finally the other beams and slabs should be poured.

[0019] S5. Install the capping steel pipe, install the prefabricated capping steel pipe, and insert the core column steel bars into the reserved holes for the longitudinal bars, and then pour the concrete in the steel pipe.

[0020] On the basis of the design drawings, the factors that may affect the opening at the construction site are predicted and taken into account in the in-depth design. The more factors considered and the more they fit the on-site construction conditions, the better the success rate of the pre-opening can be controlled, so that it not only meets the design requirements, but also paves the way for the next construction process. Through the in-depth design of the steel pipe extension method, the beam-column connection method, the steel pipe design, the steel pipe opening and the selection of the composite column foot, the steel tube concrete composite column obtained by the construction method is not only clear in force transmission, simple in structure, good in integrity, safe and reliable, but also, with the in-depth design, the on-site computer simulation is carried out to calculate the ratio It is a solution that is more suitable for the site, and the cross-section opening loss rate can be guaranteed in the design stage. Pre-opening holes on the steel pipe can predict the penetration points of the steel bars on the steel pipe in advance. The corresponding opening dimensions have been designed before the holes are opened. There are corresponding design drawings as a basis for opening holes. It is easier to operate in an off-site environment, and there are professionals to perform on-site layout and cutting. In actual operation, this mode of opening construction has a great guarantee for the quality of holes compared to on-site opening, thereby ensuring the construction quality at the source, ensuring the accuracy of the opening, saving materials, simplifying the complex, and making the construction of steel tube concrete composite columns more convenient.

[0021] According to another embodiment of the present invention, in a steel tube concrete composite column construction method, in step S1 of the in-depth design, the opening rate should be calculated by computer to determine the reasonable number of single-row steel bars in the beam. When the number of beam bars in a single row is ≥5, it is impossible to ensure that the opening loss rate is within 50%. Therefore, after communication with the designer, the number of beam bars in each row at the beam-column node is changed accordingly to control four bars in each row. Ensure that the strength of the steel pipe meets the structural requirements.

[0022] According to another embodiment of the present invention, in a construction method for steel tube concrete composite columns, in the step S1 in-depth design, the steel bars may not penetrate the steel tube column if conditions permit, while meeting the anchoring requirements, so as to reduce the opening rate of the steel tube column. In one case, some longitudinal bars in the eccentric beam may not penetrate the steel tube, and in another case, the steel bars on both sides of the inclined beam are bent at a certain angle to bend the steel tube and anchor it into the concrete column without penetrating the steel tube, so as to reduce the cross-sectional loss, increase the overall strength of the junction between the steel tube and the beam, and ensure the construction quality.

[0023] According to another embodiment of the present invention, a steel tube concrete composite column construction method, in step S1, in the deepening design, beam reinforcements in different directions are stacked on each other at the beam-column node, and the longitudinal reinforcement of the main load-bearing beam is arranged on the outermost side. In the deepening design, it is very important to predetermine the order of reinforcement penetration. Which direction is on the top and which direction is on the bottom directly affects the vertical position of the hole. The general drawing principle: first the cross-sectional direction, then the vertical direction. Control the size and number of the openings in the cross-sectional direction to keep them within 50%, and at the same time increase the vertical length of the openings.

[0024] According to another embodiment of the present invention, a construction method of steel tube concrete composite columns, in the step S1 detailed design, equal diameter steel tubes are extended, equal strength groove butt welds are used, and thicker wall lining plates are set at the steel tube connections as backing for the on-site annular welds. When straight welds are used, the welds should be staggered at the butt joints to increase the strength and bearing capacity of the steel tube connections.

[0025] According to another embodiment of the present invention, a construction method for steel tube concrete composite columns, in the step S1 deepening design, steel pipes of different diameters are extended by using a trumpet tube transition section or a connecting plate with a central hole or an extension connection method of a flange and bolt connection. When a trumpet tube transition section is used, annular partitions should be set at both ends as shear connectors, the wall thickness of the reduced diameter end should not be less than the wall thickness of the connected steel pipe, the slope of the reduced diameter section should not be greater than 1:4, and the reduced diameter section should be set within the height range of the floor structure. When a connecting plate is used, the diameter difference of the connected steel pipes should not be greater than 50mm, a hole should be opened in the center of the connecting plate, and the thickness should not be less than 16mm. When a flange and bolt connection is used, the strength requirements should also be met, and a hole should be opened in the center of the flange to make the concrete in the pipe continuous. Select a suitable steel pipe extension method according to the arrangement of the transverse reinforcement at the steel pipe connection.

[0026] According to another embodiment of the present invention, a construction method for steel tube concrete composite columns, in the step S1 deepening design, when the steel tube does not penetrate at the beam-column node, the core area of ​​the node can be converted into a small-diameter thick-walled steel tube and a steel plate fin for welding connection. The sum of the cross-sectional areas of the core steel tube, fins and steel bars should not be less than 50% of the larger cross-sectional area of ​​the connected steel tube. The number of fins should be 4, and the fins and the core steel tubes should be welded along the entire length with double-sided fillet welds. The core steel tube and fins should extend into the top and bottom skins of the beam by no less than 300 mm, and be inserted into the steel tube installation grooves of the upper and lower floors, and welded to the steel tubes with double-sided fillet welds along the entire length of the connection part, and stiffening ribs can be added if necessary. Two longitudinal bars of each row of beams should be welded to the fins, and other steel bars can pass through the fins to penetrate the core area, and holes can be opened on each fin according to the position of the steel bars.

[0027] According to another embodiment of the present invention, a construction method of a steel tube concrete composite column, in step S1 of the in-depth design, the steel plate used to make the steel tube is Q235 or Q345 grade steel, the diameter of the steel tube shall not be less than 1 / 3 of the length of the short side of the column section, and shall not be less than 200 mm, the wall thickness shall not be less than 6 mm, when Q235 grade steel is used, the ratio of the outer diameter of the steel tube to the wall thickness is 25 to 90, when Q345 grade steel is used, the ratio of the outer diameter of the steel tube to the wall thickness is 25 to 75. Ensure that the steel tube has sufficient bearing capacity.

[0028] According to another embodiment of the present invention, a steel tube concrete composite column construction method, in the step S1 in-depth design, more complex reinforced concrete beams and composite columns are connected or the beam longitudinal reinforcement directly penetrates the steel tube. The steel tube hole design principle is based on the design drawings and specifications, as well as other factors that may affect the penetration of the steel bar through the steel tube, including the elevation of the installed steel tube mouth, the actual position of the column longitudinal reinforcement, the wall thickness of the steel tube, and the order of reinforcing bars. It is simulated by AutoCAD software. In the computer simulation process, the size of each steel tube section and the position and size of the hole through which the steel bar penetrates the steel tube are calculated through the steps of reinforcing bars, arranging holes in the cross-sectional direction, drawing elevation control lines, and arranging holes in the vertical direction. A certain amount of redundant space for reinforcing bars needs to be reserved when designing the holes. Finally, it is necessary to check and calculate whether the section opening loss rate exceeds the allowable value specified in the specification. If it exceeds the allowable value range, it should be redesigned or reinforcement measures should be formulated.

[0029] According to another embodiment of the present invention, a construction method for steel tube concrete composite columns, in the step S1 deepening design, the column base of the composite columns is constructed by embedded or end-bearing. The embedded column base is suitable for composite columns with independent column foundations. The column base insertion depth should not be less than 2 times the diameter of the steel pipe. The end-bearing column base is suitable for composite columns with steel pipes extending to the ground of one underground floor. The composite column concrete pouring construction form is determined by the design to adopt different phases of construction or simultaneous construction. Different phases of construction is to first pour the concrete in the tube to form steel tube concrete, which bears part of the vertical load during the construction period, and then pour the concrete outside the steel tube.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A construction method for steel tube concrete composite columns, characterized in that: The following steps are involved: S1. In-depth design, including the following: 1) Select the steel pipe extension method. Select the appropriate type of steel pipe for extension according to the design drawings, and the reliability should be verified. 2) Select the beam-column connection method. The beam-column connection must be selected according to the structural characteristics of the design drawings and the building layout. The appropriate type includes the connection between steel beams and composite columns and the connection between reinforced concrete beams and composite columns, and the reliability should be verified. 3) Steel pipe design. Select steel pipes with appropriate strength and length. Determine the openings for passing steel bars on the steel pipes according to the relative positions of the pre-installed steel pipes on the floors. Use AutoCAD software to simulate and calculate. During the simulation, the size of each steel pipe section and the position and size of the holes through which the steel bars penetrate the steel pipe are calculated through the steps of laying out the reinforcement, arranging holes in the cross-section direction, drawing the elevation control line, and arranging holes in the vertical direction. When designing the holes, a certain amount of spare space for reinforcing bars should be reserved. Finally, a check is performed to calculate whether the section opening loss rate exceeds the allowable value specified in the specification. If it exceeds the allowable value range, the design should be redesigned or reinforcement measures should be formulated. At the same time, the opening rate should be calculated by computer to determine the reasonable number of single-row steel bars in the beam. 4) Selection of the column foot of the composite column: adopt the corresponding reliable and effective column foot form according to the different foundation forms; S2. Processing of steel components, including the following: 1) Fabrication of steel pipes and accessories, manufacturing steel pipes according to the dimensions required by the design and detailed drawings, including reserved grooves at the steel pipe joints, welding cylindrical head bolts on the outside of the steel pipes, popping up the reference axis on the steel pipes for positioning the constructed steel pipe superimposed columns, and opening holes in the reserved positions for the longitudinal reinforcement of the steel pipe upper beams, manufacturing steel component accessories according to the dimensions required by the design and detailed drawings, including positioning plates, lining pipes, and reinforced rib plates; 2) Pre-assembly of steel components, assembling various steel components including positioning plates, column bases, natural steel pipe sections, and capping steel pipe sections in the processing plant; S3. Installation of the composite column positioning plate and column foot. According to the design and detailed drawing requirements, multiple screws for fixing the positioning plate are fixed and tied on the corresponding steel mesh. Two layers of nuts are threaded on the screws. The lower layer of nuts are welded to the screws after leveling the positioning plate. The column foot is hoisted. The bottom plate of the column foot corresponds to the positioning plate. The screw passes through the bottom plate. After leveling the bottom plate of the column foot with the upper layer of nuts, the double nuts are tightened on the screws and welded to the screws. S4. Construction of natural layer steel pipes for composite columns includes the following: 1) Lifting the extended steel pipes, clean the concrete at the mouth of the installed steel pipes, then lift the extended steel pipes to the operating surface, fix the tower crane steel cable on the top of the extended steel pipes, lift them vertically above the installed steel pipes, slowly place them on the installed steel pipes, and roughly align them. The operator hangs a magnetic line plumb on the top of the extended steel pipes to control the vertical deviation of the extended steel pipes, and uses a crowbar to make fine adjustments until they are fully aligned. The hooks are not removed during this process. 2) Install the ear plates, spot weld them to the installed and extended steel pipes respectively, and then spot weld them at the seams of the installed and extended steel pipes for preliminary fixation, and then remove the hooks. 3) Steel pipe welding: After installing the ear plates, use manual arc welding to weld the installed and extended steel pipes. The welds are equal-strength groove butt welds. 4) Tie the column reinforcement. Tie the column longitudinal reinforcement and stirrups according to the requirements of the drawings. 5) Support the column formwork. Install the composite column formwork according to the special formwork construction plan. 6) Pour the concrete inside the steel tube. The concrete inside the tube should be dropped from a high position without vibration. After pouring, the tube should be closed. 7) Pour the concrete outside the steel tube. The concrete outside the tube should be fine stone concrete. 8) Pass the beam reinforcement. After the beam formwork is completed, the steel bars should be passed through the steel tube according to the hole position, and then the steel bars should be connected. 9) Pour the concrete at the beam-column node. The strength grade of the beam-column node is higher than that of the beam-slab concrete. The node is blocked with wire mesh. The concrete inside the steel tube in the core area should be poured first, and then the concrete outside the steel tube in the core area should be poured. Finally, other beams and slabs should be poured. S5. Install the capping steel pipe, install the prefabricated capping steel pipe, and insert the core column steel bars into the reserved holes for the longitudinal bars, and then pour the concrete in the steel pipe.

2. A steel tube concrete composite column construction method as claimed in claim 1, characterized in that: In the detailed design of step S1, the steel bars can avoid penetrating the steel pipe column if conditions permit, provided that the anchoring requirements are met, so as to reduce the opening rate of the steel pipe column.

3. A steel tube concrete composite column construction method as claimed in claim 1, characterized in that: In the detailed design of step S1, beam reinforcements in different directions are stacked on top of each other at the beam-column joints, and the longitudinal reinforcements of the main load-bearing beams are arranged on the outermost side.

4. A construction method for steel tube concrete composite columns as claimed in claim 1, characterized in that: In the step S1 in-depth design, equal diameter steel pipes are extended and equal strength groove butt welds are adopted. A thicker lining plate is set at the connection of the steel pipes as the backing of the on-site annular weld. When straight welds are used, the welds should be staggered at the butt joints.

5. The construction method of a steel tube concrete composite column as claimed in claim 1, characterized in that: In the detailed design of step S1, steel pipes of different diameters are connected by using a flared transition section, a connecting plate with a central opening, or a flange and bolt connection.

6. A construction method for steel tube concrete composite columns as claimed in claim 1, characterized in that: In the detailed design of step S1, when the steel pipe does not penetrate at the beam-column node, the core area of ​​the node can be converted into a small-diameter thick-walled steel pipe and a steel plate fin for welding connection.

7. A construction method for steel tube concrete composite columns as claimed in claim 1, characterized in that: In the step S1 in-depth design, the steel plate used to make the steel pipe is Q235 or Q345 grade steel. The diameter of the steel pipe shall not be less than 1 / 3 of the length of the short side of the column section and shall not be less than 200 mm. The wall thickness should not be less than 6 mm. When Q235 grade steel is used, the ratio of the steel pipe outer diameter to the wall thickness is 25 to 90. When Q345 grade steel is used, the ratio of the steel pipe outer diameter to the wall thickness is 25 to 75.

8. The construction method of a steel tube concrete composite column as claimed in claim 1, characterized in that: In the detailed design of step S1, the base of the composite column is constructed by embedded or end-bearing method, and the concrete pouring construction of the composite column is carried out in different phases or at the same time according to the design.