A steel pipe concrete column and composite column connecting joint and construction method

Abstract

The application relates to a kind of steel pipe concrete column and composite column connecting joint and construction method, the joint includes steel pipe concrete column steel pipe extending to beam top, composite column internal steel pipe extending to steel pipe concrete, stiffened plate connecting internal and external steel pipes, annular column base bottom plate with grout hole, joint area composite column internal steel pipe wall tack-welded short steel bar, composite column longitudinal reinforcement, steel sleeve.The joint makes full use of the shear strength of stiffened plate, the bonding strengthening effect of joint area composite column internal steel pipe wall welded short steel bar, the local pressure bearing capacity of composite column internal steel pipe end column base bottom plate, realizes the force transition of composite column internal steel pipe to steel pipe concrete column, the uniform separation formed by stiffened plate and the grout hole are beneficial to the pumping, flowing and pouring of concrete;Reserved steel sleeve facilitates the connection of column longitudinal reinforcement on construction site, reduces the amount of site welding.A number of measures ensure the strong node effect, effectively solve the node connection problem of high-rise or super high-rise building vertical support column transition.

Description

Technical Field

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

[0002] Concrete-filled steel tube columns are steel-concrete composite components with high bearing capacity and excellent seismic performance. They fully utilize the material properties of steel and concrete and are often used as external frame columns in high-rise and super-high-rise buildings. According to force calculations, the cross-section and material strength of concrete-filled steel tube columns generally decrease with increasing building height, or composite concrete-filled steel tube columns or reinforced concrete columns are used in the upper part of the building to save costs. Furthermore, the vertical support columns of high-rise buildings are usually critical components. To avoid sudden changes in their ductility, a transition from concrete-filled steel tube columns to composite concrete-filled steel tube columns to reinforced concrete columns is required as the load on them changes. Therefore, a reasonable, reliable, and easy-to-construct transition connection node from concrete-filled steel tube columns to composite concrete-filled steel tube columns is required to achieve efficient connection of the upper and lower structural support columns.

[0003] The current standards and regulations do not provide construction methods for the connection nodes of steel tube concrete columns and composite columns. There are few mature construction schemes for this type of nodes. In recent years, some patents have involved the transition problem of columns with different cross-sections at the nodes. CN119332829B discloses a splicing node of steel tube concrete composite columns and reinforced concrete columns. The longitudinal reinforcement of the reinforced concrete column is inserted into the space formed by the steel tube and the corrugated steel plate for pouring high-ductility concrete through a straight anchor to form a force transmission transition. The longitudinal reinforcement and the corrugated steel plate need to be welded or closed. Different types of concrete are poured in different spaces in the node area. The restraint and anchoring performance of the corrugated steel plate with a relatively small thickness on the concrete outside the steel tube in the node area needs to be studied. The amount of on-site welding is large, the process is complicated, the force transmission performance is not clear, and it does not involve the transition between steel tube concrete columns and composite columns; CN113216417B discloses A connection node for transitioning from a rectangular steel tube concrete column to a steel-concrete column utilizes a transition section located above the node area formed by upper and lower column foot plates, stiffening plates and outer column walls to achieve transitions between different column cross-sections. Grouting holes are provided in the upper and lower column foot plates of the transition section to divide the section into several casting spaces. The upper column longitudinal reinforcement is welded to the longitudinal reinforcement connection plate, and the upper column steel section, the longitudinal reinforcement connection plate and the stiffening plate therebetween are welded to the upper column foot plate. There are multiple force transmission pathways, a large amount of steel used, and a large amount of on-site welding. Furthermore, the node does not involve the transition between the steel tube concrete column and the composite column. The transition section located above the node area is often restricted by the building function or the fire protection method of the steel tube concrete column.

[0004] In summary, the existing technology does not solve the connection node problem of transitioning from steel tube concrete columns to composite columns. Summary of the Invention

[0005] In response to the problems existing in the prior art, the purpose of the present invention is to provide a connection node and construction method for steel tube concrete columns and composite columns, which can form a strong node with the advantages of clear force transmission, high bearing capacity, excellent seismic performance, steel saving, and high degree of construction standardization, and effectively solve the node connection problem of the transition of vertical support columns in high-rise or super-high-rise buildings.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A connection node between a steel tube concrete column and a composite column, comprising a composite column internal steel tube, composite column longitudinal reinforcement, a steel tube concrete column, a first steel sleeve, a stiffening plate, and short steel bars;

[0008] The steel tube of the concrete-filled steel tube column extends vertically from bottom to top to the top surface of the beam, and the steel tube inside the composite column extends vertically from top to bottom into the concrete-filled steel tube column;

[0009] The steel tubes of the concrete-filled steel tube columns and the internal steel tubes of the composite columns are connected in the node area through multiple stiffening plates for force transmission, and the multiple stiffening plates are evenly spaced;

[0010] The end of the steel pipe inside the composite column is provided with an annular column base plate, and the annular column base plate is provided with a grouting hole;

[0011] Short steel bars are welded on both sides of the outer wall of the steel tube inside the composite column in the node area;

[0012] The first steel sleeve is welded to the inner side of the top of the steel tube concrete column, and the longitudinal reinforcement of the composite column is connected to the first steel sleeve.

[0013] Furthermore, a certain length of longitudinal reinforcement of the composite column is reserved and the requirement that the percentage of the steel bar lap joint area is not less than 50% is met.

[0014] Furthermore, the composite column longitudinal reinforcement includes a factory reserved section of the composite column longitudinal reinforcement and an on-site section of the composite column longitudinal reinforcement. The factory reserved section of the composite column longitudinal reinforcement is connected to the first steel sleeve, and a second steel sleeve is reserved at its end. The on-site section of the composite column longitudinal reinforcement is connected to the second steel sleeve.

[0015] Furthermore, the length of the short steel bar is not less than 5 times the diameter of the short steel bar, and the width of the annular column base plate is not less than 6 times the thickness of the steel pipe inside the composite column.

[0016] Furthermore, the steel tube concrete column steel tube and the internal steel tube of the composite column are respectively provided with notches at corresponding tube wall positions in the node area, and the stiffening plates are embedded in the notches and installed in place.

[0017] Furthermore, a groove is formed at the notch of the pipe wall, and after the stiffening plate is embedded in the notch, a first-level full penetration welding is performed at the groove.

[0018] Furthermore, the number and size of the stiffening plates are determined according to calculation requirements, and the stiffening plates are evenly arranged along the walls of the steel tube concrete columns and the internal steel tubes of the composite columns, with horizontal spacing between 100mm and 200mm.

[0019] The construction method of the connection node between the steel tube concrete column and the composite column includes the following steps:

[0020] S1: Determine the height of the steel tube protruding from the beam surface inside the composite column and the height of the steel tube concrete column protruding from the bottom of the beam;

[0021] S2: Process the steel tube concrete column steel pipe and the internal steel pipe of the composite column in the steel structure factory, and determine the number and size of the stiffening plates through calculation;

[0022] S3: Embed the stiffening plate into the steel pipe inside the composite column and use first-level full penetration welding;

[0023] S4: Double-sided welding of short steel bars on the inner steel pipe wall of the composite column in the node area;

[0024] S5: A grouting hole is reserved on the annular column base plate, and the end of the steel pipe inside the composite column and the annular column base plate are welded with a first-level full penetration welding method;

[0025] S6: The composite column internal steel pipe with a stiffening plate, an annular column foot plate, and short steel bars formed in the above steps are integrally embedded in the steel pipe of the steel tube concrete column and welded using a first-level full penetration method, so that the steel pipe of the steel tube concrete column extends vertically from bottom to top to the top surface of the beam, and the internal steel pipe of the composite column extends vertically from top to bottom into the steel tube concrete column, and the steel pipe of the steel tube concrete column and the internal steel pipe of the composite column are connected in the node area by a stiffening plate for force transmission, a first steel sleeve is welded to the inner wall of the top of the steel pipe of the steel tube concrete column, and the longitudinal reinforcement of the composite column is connected to the first steel sleeve;

[0026] S7: The processed node skeleton is transported to the site and hoisted and spliced. Concrete is poured through the uniform separation formed between the stiffening plates and / or the slurry holes, and then cured to obtain the connection node of the steel tube concrete column and the composite column.

[0027] Furthermore, the composite column longitudinal reinforcement includes a factory reserved section of the composite column longitudinal reinforcement and an on-site section of the composite column longitudinal reinforcement. The factory reserved section of the composite column longitudinal reinforcement is connected to the first steel sleeve, and the percentage of the steel bar lap joint area is not less than 50%. A second steel sleeve is reserved at the end of the factory reserved section of the composite column longitudinal reinforcement, and the on-site section of the composite column longitudinal reinforcement is connected to the second steel sleeve.

[0028] Furthermore, the insertion length L of the internal steel pipe of the composite column into the steel tube concrete column is determined by the following formula and shall not be less than the diameter of the internal steel pipe of the composite column:

[0029] ;

[0030] Where, is the design value of the tensile and compressive strength of the steel pipe inside the composite column, is the cross-sectional area of ​​the steel pipe inside the composite column, n is the number of stiffeners, the height of the stiffener is equal to the insertion length L, the spacing between the stiffeners is controlled at 100mm-200mm, and t is the thickness of the stiffener. is the design value of shear strength of the stiffener.

[0031] In general, the present invention has the following advantages:

[0032] 1) Clear force transmission and safe and reliable calculations: This connection between the CFST column and the composite column fully utilizes the shear strength of the stiffening plate, the bonding reinforcement effect of the short steel bars welded to the steel tube wall of the composite column in the node area, and the local compressive bearing capacity of the annular column footing plate at the end of the steel tube inside the composite column to achieve the force transition from the steel tube inside the composite column to the CFST column. The number and size of the stiffening plates are determined through calculation. The longitudinal reinforcement of the composite column is directly connected to the CFST column steel tube through the first and second steel sleeves, ensuring the transmission of internal forces and a clear and controllable force transmission path. These measures can ensure the bearing capacity, seismic performance, and integrity of the node, achieving a strong node.

[0033] 2) Reasonable structure and easy construction: The uniform separation between multiple stiffening plates and the slurry holes in the annular column base plate facilitate the pumping, flow and pouring of concrete; the reserved first and second steel sleeves facilitate the connection of the longitudinal reinforcement of the composite columns on the construction site, reduce the amount of on-site welding, and improve the degree of standardization.

[0034] 3) Economical: The transition from concrete-filled steel tubular columns to composite columns significantly reduces steel usage. Nodes are standardized and fabricated in a steel structure factory, reducing complex on-site processes. While maintaining structural performance, this significantly reduces material and construction costs, resulting in significant economic benefits.

[0035] 4) High degree of standardized processing: The nodes are processed as a whole in the steel structure factory, combined with on-site hoisting measures to reduce on-site welding workload; the slot embedded connection is conducive to the installation of the stiffening plate, and multiple equal strength welding ensures the quality of the node.

[0036] This node effectively solves the node connection problem of the transition of vertical support columns in high-rise or super-high-rise buildings, and has broad prospects in the development and application of steel-concrete composite structure systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the connection node between the steel tube concrete column and the composite column of the present invention.

[0038] Figure 2 for Figure 1 AA section view in.

[0039] Figure 3for Figure 1 BB cross-section diagram in.

[0040] Figure 4 for Figure 1 CC cross-section diagram in .

[0041] Figure 5 Schematic diagram of the first partial three-dimensional structure of the node of the present invention.

[0042] Figure 6 Schematic diagram of the second partial three-dimensional structure of the node of the present invention.

[0043] Figure 7 Schematic diagram of the overall three-dimensional structure of the node of the present invention.

[0044] In the picture:

[0045] 1 is the composite column, 2 is the steel tube concrete column, 3 is the beam, 4 is the internal steel tube of the composite column, 5 is the composite column longitudinal reinforcement, 5a is the factory reserved section of the composite column longitudinal reinforcement, 5b is the on-site section of the composite column longitudinal reinforcement, 6 is the stiffening plate, 7 is the short steel bar, 8 is the annular column base plate, 9 is the steel tube concrete column steel tube, 10 is the notch, 11a is the first steel sleeve, and 11b is the second steel sleeve. DETAILED DESCRIPTION

[0046] The present invention proposes a connection node between a steel tube concrete column and a composite column. This node fully utilizes the shear strength of the stiffening plate 6, the bonding reinforcement effect of the short steel bars 7 welded to the wall of the composite column's internal steel tube 4 in the node area, and the local compressive bearing capacity of the annular column footing plate 8 at the end of the composite column's internal steel tube 4 to achieve force transfer from the internal steel tube 4 of the composite column to the steel tube concrete column 2. The number and size of the stiffening plates 6 are determined by calculation. The node is completely processed in the factory. The embedded connection of the notch 10 facilitates the installation of the stiffening plates 6. Multiple equal strength welds ensure the quality of the node. The uniform separation formed by the stiffening plate 6 and the grouting holes of the annular column footing plate 8 facilitate the pumping, flow, and pouring of concrete. The reserved first and second steel sleeves 11a and 11b facilitate the connection of the longitudinal reinforcement of the composite column at the construction site, reducing the amount of on-site welding. Through calculation, construction, and processing measures, a strong node effect is ensured. It has the advantages of clear force transmission, high bearing capacity, excellent seismic performance, and a high degree of construction standardization. It effectively solves the node connection problem of the transition of vertical support columns in high-rise or super-high-rise buildings.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings.

[0048] like Figure 1-Figure 7 As shown, a connection node between a steel tube concrete column and a composite column, the composite column 1 includes a composite column internal steel tube 4 and a composite column longitudinal reinforcement 5, and the steel tube concrete column 2 includes a steel tube concrete column steel tube 9.

[0049] Specifically, the steel tube concrete column steel pipe 9 extends vertically from bottom to top to the height of the top surface of the beam 3, and the internal steel pipe 4 of the composite column extends from top to bottom into the steel tube concrete column 2. The extension length L is calculated and determined by the following formula and is not less than the diameter of the internal steel pipe 4 of the composite column:

[0050] ;

[0051] Where, is the design value of the tensile and compressive strength of the steel pipe 4 inside the composite column, is the cross-sectional area of ​​the steel pipe 4 inside the composite column, n is the number of stiffening plates 6, the height of the stiffening plates 6 is equal to the insertion length L, the spacing between the stiffening plates 6 is controlled at 100mm-200mm, t is the thickness of the stiffening plates 6, is the design value of shear strength of stiffener 6.

[0052] Specifically, an annular column foot plate 8 is provided at the end of the composite column internal steel tube 4. Most of the internal force applied to the composite column internal steel tube 4 is transmitted to the steel tube concrete column steel tube 9 through the stiffening plate 6. The addition of the annular column foot plate 8 at the bottom of the steel tube concrete column can increase the contact area with the concrete inside the tube to prevent local pressure damage.

[0053] Specifically, the composite column longitudinal reinforcement 5 consists of a factory-prepared section 5a and an on-site section 5b. The factory-prepared section 5a connects to a first steel sleeve 11a welded to the top inner side of the steel tube 9 of the concrete-filled steel tubular column. A second steel sleeve 11b is reserved at the end of the factory-prepared section 5a, facilitating direct connection with the on-site section 5b after on-site installation of the integral joint, eliminating welding workload. The factory-prepared section 5a extends from the beam to a length that is essentially the same as the internal steel tube 4 of the composite column (approximately 1 meter), and must meet the requirement that the reinforcement lap joint area percentage be no less than 50%.

[0054] Specifically, short steel bars 7 are welded on both sides of the outer wall of the steel pipe 4 inside the composite column in the node area of ​​the composite column 1, and the length of the short steel bars 7 is not less than 5 times its diameter.

[0055] Specifically, the steel tube concrete column steel pipe 9 is connected to the internal steel pipe 4 of the composite column through a stiffening plate 6. The pipe walls of the steel tube concrete column steel pipe 9 and the internal steel pipe 4 of the composite column are provided with a notch 10 and a bevel in the node area. The stiffening plate 6 is embedded in the notch 10 and adopts a first-level full penetration welding.

[0056] Specifically, a grouting hole is provided in the center of the annular column base plate 8 to facilitate the passage of the pouring conduit and the flow and vibration of concrete. During pouring, the conduit passes through the grouting hole inside the composite column internal steel pipe 4 and is gradually lifted from bottom to top, with concrete flowing and vibrating simultaneously. The width of the annular column base plate 8 is no less than 6 times the thickness of the composite column internal steel pipe 4.

[0057] The present invention utilizes a "triple synergy" for force transmission: stiffening plates 6 directly transmit shear forces between the composite column's internal steel tubes 4 and the concrete-filled steel tube column's steel tubes 9; annular column footings 8 disperse localized pressure, preventing localized concrete damage; short steel bars 7 enhance the bond between the steel tubes and concrete; and first and second steel sleeves 11a and 11b ensure direct force transmission from the composite column's longitudinal reinforcement 5. This triple synergy ensures a "strong node effect," improving bearing capacity and seismic performance.

[0058] The present invention also provides a construction method for the connection node between the above-mentioned steel tube concrete column and the composite column, the method comprising the following steps:

[0059] S1: Based on the processing and transportation capacity of the steel structure factory and the on-site lifting capacity, determine the height of the 4 steel tubes in the composite column extending out of the 3 sides of the beam (1m is recommended) and the height of the 9 steel tubes in the steel tube concrete column extending out of the 3 bottoms of the beam (0.5m is recommended).

[0060] S2: The CFST column steel tube 9 and the composite column internal steel tube 4 are processed in a steel structure factory. According to the number and size of the stiffening plates 6 determined by calculation, notches 10 are provided on the steel tube walls of the CFST column steel tube 9 and the composite column internal steel tube 4 in the node area and beveled. The ends of the composite column internal steel tube 4 are beveled.

[0061] S3: Insert the stiffening plate 6 into the notch 10 of the steel pipe 4 inside the composite column, and use a first-level full penetration welding at the groove;

[0062] S4: Double-sided welding of short steel bars 7 on the wall of the steel tube 4 inside the composite column in the node area;

[0063] S5: A grouting hole is reserved on the annular column base plate 8, and the end of the steel pipe 4 inside the composite column is welded to the annular column base plate 8 by a first-level full penetration welding method;

[0064] S6: The composite column internal steel pipe 4 with the stiffening plate 6, the annular column foot plate 8, and the short steel bars 7 formed in the above steps are integrally embedded in the notch 10 of the steel tube concrete column steel pipe 9 and welded using a first-level full penetration welding method. A first steel sleeve 11a is welded to the top inner wall of the steel tube concrete column steel pipe 9. The factory-reserved section 5a of the composite column longitudinal reinforcement is connected to the first steel sleeve 11a. A second steel sleeve 11b is reserved at the end of the factory-reserved section 5a of the composite column longitudinal reinforcement to facilitate connection with the on-site section 5b of the composite column longitudinal reinforcement.

[0065] S7: Transport the processed node skeleton to the site and complete the hoisting and splicing, pouring concrete, and curing to obtain the steel tube concrete column and composite column connection node.

[0066] The unique features of the construction process of this invention include "factory standardized processing and on-site rapid assembly":

[0067] The stiffening plate 6, short steel bars 7, annular column base plate 8, first steel sleeve 11a and second steel sleeve 11b are all manufactured in the factory. Only hoisting, splicing and concrete pouring are required on site. The combination of stiffening plate 6 and short steel bars 7 greatly reduces the amount of steel used.

[0068] The embedded stiffening plate 6 in the slot 10 is accurately installed and positioned. The separation design of the slurry hole and the stiffening plate 6 facilitates concrete pouring and ensures that the concrete is poured densely. The first steel sleeve 11a and the second steel sleeve 11b avoid on-site longitudinal reinforcement welding.

[0069] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A connection node between a concrete-filled steel tube column and a composite column, characterized by: It includes the internal steel pipe of the composite column, the longitudinal reinforcement of the composite column, the steel tube concrete column, the first steel sleeve, the stiffening plate and the short steel bars; The steel tube of the concrete-filled steel tube column extends vertically from bottom to top to the top surface of the beam, and the steel tube inside the composite column extends vertically from top to bottom into the concrete-filled steel tube column; The steel tubes of the concrete-filled steel tube columns and the internal steel tubes of the composite columns are connected in the node area through multiple stiffening plates for force transmission, and the multiple stiffening plates are evenly spaced; The end of the steel pipe inside the composite column is provided with an annular column base plate, and the annular column base plate is provided with a grouting hole; Short steel bars are welded on both sides of the outer wall of the steel tube inside the composite column in the node area; The first steel sleeve is welded to the inner side of the top of the steel tube concrete column, and the longitudinal reinforcement of the composite column is connected to the first steel sleeve; The composite column longitudinal reinforcement includes a factory-reserved section for the composite column longitudinal reinforcement and an on-site section for the composite column longitudinal reinforcement. The factory-reserved section for the composite column longitudinal reinforcement is connected to the first steel sleeve, and a second steel sleeve is reserved at its end. The on-site section for the composite column longitudinal reinforcement is connected to the second steel sleeve. The steel tubes of the concrete-filled steel tube columns and the internal steel tubes of the composite columns are respectively provided with notches at the corresponding tube wall positions in the node areas, and the stiffening plates are inserted into the notches and installed in place; The pipe wall is grooved at the slot, and after the stiffening plate is embedded in the slot, a first-level full penetration welding is adopted at the groove.

2. The connection node of the steel tube concrete column and the composite column according to claim 1, characterized in that: A certain length of longitudinal reinforcement is reserved for composite columns and the percentage of the reinforcement lap joint area must be no less than 50%.

3. The connection node between a concrete-filled steel tube column and a composite column according to claim 1, characterized in that: The length of the short steel bar shall not be less than 5 times the diameter of the short steel bar, and the width of the annular column base plate shall not be less than 6 times the thickness of the steel pipe inside the composite column.

4. The connection node between a concrete-filled steel tube column and a composite column according to claim 1, characterized in that: The number and size of stiffening plates are determined according to calculation requirements. The stiffening plates are evenly arranged along the walls of the steel tube concrete columns and the internal steel tubes of the composite columns, with horizontal spacing between 100mm and 200mm.

5. The construction method of the connection node of the steel tube concrete column and the composite column according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Determine the height of the steel tube protruding from the beam surface inside the composite column and the height of the steel tube concrete column protruding from the bottom of the beam; S2: Process the steel tube concrete column steel pipe and the internal steel pipe of the composite column in the steel structure factory, and determine the number and size of the stiffening plates through calculation; S3: Embed the stiffening plate into the steel pipe inside the composite column and use first-level full penetration welding; S4: Double-sided welding of short steel bars on the steel pipe wall of the composite column in the node area; S5: A grouting hole is reserved on the annular column base plate, and the end of the steel pipe inside the composite column and the annular column base plate are welded with a first-level full penetration welding method; S6: The composite column internal steel pipe with a stiffening plate, an annular column foot plate, and short steel bars formed in the above steps are integrally embedded in the steel pipe of the steel tube concrete column and welded using a first-level full penetration method, so that the steel pipe of the steel tube concrete column extends vertically from bottom to top to the top surface of the beam, and the internal steel pipe of the composite column extends vertically from top to bottom into the steel tube concrete column, and the steel pipe of the steel tube concrete column and the internal steel pipe of the composite column are connected in the node area by a stiffening plate for force transmission, a first steel sleeve is welded to the inner wall of the top of the steel pipe of the steel tube concrete column, and the longitudinal reinforcement of the composite column is connected to the first steel sleeve; S7: The processed node skeleton is transported to the site and hoisted and spliced. Concrete is poured through the uniform separation and / or slurry holes formed between the stiffening plates and cured to obtain the connection node of the steel tube concrete column and the composite column.

6. The construction method according to claim 5, characterized in that: The longitudinal reinforcement of the composite column includes the factory reserved section of the composite column longitudinal reinforcement and the on-site section of the composite column longitudinal reinforcement. The factory reserved section of the composite column longitudinal reinforcement is connected to the first steel sleeve, and the percentage of the steel bar lap joint area is not less than 50%. A second steel sleeve is reserved at the end of the factory reserved section of the composite column longitudinal reinforcement, and the on-site section of the composite column longitudinal reinforcement is connected to the second steel sleeve.

7. The construction method according to claim 5, characterized in that: The insertion length L of the internal steel tube of the composite column into the steel tube concrete column is determined by the following formula and shall not be less than the diameter of the internal steel tube of the composite column: ; Where, is the design value of the tensile and compressive strength of the steel pipe inside the composite column, is the cross-sectional area of ​​the steel pipe inside the composite column, n is the number of stiffeners, the height of the stiffener is equal to the insertion length L, the spacing between the stiffeners is controlled between 100mm and 200mm, and t is the thickness of the stiffener. is the design value of shear strength of the stiffener.

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