CN101775844A - Connecting joint of ring beam of steel core concrete column used for topdown construction method foundation pit engineering - Google Patents

Abstract

The invention belongs to a steel pipe concrete column ring beam connection node used for foundation pit engineering of reverse method for fixing underground structures of buildings. The underground structural beam (3) and the concrete-filled steel tube column (2) are connected by a reinforced concrete ring beam (1), and there is a column end (4) formed in the reverse construction directly below the column end (4). The cross-sectional size and reinforcement of the column end (4) The same as the permanent frame column after the implementation of the reverse method, the contact between the column end (4) and the steel pipe concrete column (2) is connected with the end connection peg (12), and the end connection peg (12) is welded On the outer wall of the steel pipe of the concrete-filled steel pipe column (2), it is arranged at intervals along the outer circumference of the steel pipe wall of the concrete-filled steel pipe column (2). As an optimization, ring bars (6) or pegs (5) can also be arranged at the connection between the steel pipe column and the ring beam. Adopting this joint can not only completely avoid the crossing problem of steel bars at the beam-to-column joints of CFST columns, but also solve the problem of shear bearing capacity of concrete ring beams and CFST columns.

Description

A Connecting Node of Concrete Steel Tube Column and Ring Beam Used in Foundation Pit Engineering of Upside-Down Method

technical field

The invention belongs to the beam-column node structure of the underground structure of a fixed building, and in particular relates to a foundation pit project using a steel pipe concrete column in the reverse method.

Background technique

The reverse method of foundation pit engineering is a construction method that combines the main structure and the supporting structure in an all-round way. Generally, the underground diaphragm wall or other temporary enclosure walls are constructed along the exterior wall of the basement of the building, and at the same time, the permanent walls inside the building are constructed. The position of the frame column shall be constructed with intermediate support piles and columns, as a support for bearing the self-weight and construction load of the superstructure before the bottom plate is sealed during construction; then construct the beam-slab structure of the main structure, as the horizontal support of the underground diaphragm wall or other enclosure walls, and then Excavate the earth and pour the underground structural beams and slabs layer by layer until the base plate is sealed. After the reverse construction is completed, the columns are covered with reinforced concrete to form a permanent frame column; at the same time, since the floor structure of the ground floor has been completed, The construction of the upper structure creates conditions, so the construction of the above-ground structure can be carried out layer by layer upward at the same time; in this way, the construction is carried out simultaneously on the ground and below the ground until the project is completed.

Due to the advantages of strictly controlling the deformation of the foundation pit, saving the cost of the foundation pit enclosure structure, and speeding up the construction period, the reverse method has been widely used and promoted in foundation engineering of high-rise buildings, subway stations, civil air defense, and municipal engineering in recent years. It has achieved good economic and social benefits, and has accumulated relatively mature design and construction experience. At the same time, it has become more and more perfect in theory, and has been included in national, industry and local standards. One of the 10 new technologies in the industry.

For high-rise and super-high-rise structures with large superstructure loads, it is often necessary to use concrete-filled steel tube columns as vertical supports for the superstructure. Concrete-filled steel pipe columns make full use of the interaction between steel pipes and core concrete, and have the mechanical properties of high strength, good plasticity, fatigue resistance and impact resistance. The combination of the two materials is in line with the development direction of improving the strength of building materials. With the maturity and perfection of the column shaft theory, the application of concrete filled steel tube structures in factory construction is increasing, especially in high-rise buildings. The CFST column-beam joints of the upper structure can be divided into column penetration and beam penetration. In column penetration, there are internal reinforcement ring type, external reinforcement ring type, ring beam type, steel bar penetration type, double beam type, etc., while in beam penetration there are Beam through-type, beam flange through-type, partition through-type, beam web through-type and other forms. However, there is a problem that the research on concrete-filled steel pipe column joints is not yet mature and perfect, and there is no report on the research on underground beam-column joints of steel-filled steel tube concrete columns in reverse engineering of foundation pits.

According to the technological characteristics of the upside-down method itself, the vertical support in the upside-down method project should be constructed from the ground before excavation of the foundation pit, and used as the vertical support of the underground and above-ground structure during the upside-down method construction process. At present, the vertical support adopts the type of steel columns combined with column piles. For the reverse engineering of steel columns using high-rise concrete-filled steel tube columns, due to the large diameter of steel tube concrete columns, it is generally about 800mm to 1000mm. The beam width of the underground structure is relatively small, generally about 500mm to 800mm. At the underground beam-column joint position, there is a problem that the beam reinforcement at the beam-column joint position is cut off by the concrete-filled steel tube column, and the beam reinforcement is difficult to pass through. Although with the implementation of a large number of concrete structure projects with steel pipe concrete columns, various joint connection methods have been developed in the superstructure engineering to solve this problem. For the underground structure reverse method, because the steel pipe concrete columns bear the load of the superstructure, beams cannot be used. The form of penetration must adopt the node of column penetration.

Commonly used column-through-beam-column joints need to weld a reinforcing ring on the surface of the steel tube concrete column, and the beam steel bar is connected to the steel tube concrete column by welding on the reinforcing ring plate. However, the welded reinforcing ring has adverse effects on the construction and stress of the CFST column. If the steel tube concrete column is welded before construction, it is not conducive to the construction of the steel tube concrete column before the excavation of the foundation pit; Welding stress weakens the strength of CFST columns. Concrete-filled steel tube column-beam-column joints connected by conventional reinforced concrete ring beams can avoid the welding problem of the reinforced ring slab, but because the underground structure of the reverse construction method needs to bear a large vertical construction load, the top structure of the basement needs to be used as a construction platform for reverse construction. During the implementation process, excavators, cranes, earth trucks and concrete pump trucks and other large heavy-duty construction machinery work. Conventional steel pipe concrete ring beam joints are used to transmit shear force by pasting and welding ring steel bars on the outer surface of steel pipes in the middle or bottom of the ring beam. How to ensure the shear bearing capacity of concrete ring beams and CFST columns under large reverse construction loads is a problem that needs to be solved by using reinforced concrete ring beam connections.

To sum up, the conventional concrete-filled steel tube column ring-beam connection cannot be directly applied to the underground structure of the reverse construction method, resulting in the connection of the steel bars at the beam-column joints, the inability to adopt the reinforced ring-slab connection, and the shear capacity of the concrete ring beam and the concrete-filled steel tube column Power issues and many other unfavorable factors.

Contents of the invention

In order to overcome the connection problem of steel bars at beam-column node positions in the existing upside-down foundation pit engineering using steel tube concrete columns, the present invention provides a new beam-column node for the upside-down foundation pit engineering using steel tube concrete columns. Adopting this joint can not only completely avoid the crossing problem of steel bars at the beam-to-column joints of CFST columns, but also solve the problem of shear bearing capacity of concrete ring beams and CFST columns.

In order to solve the above technical problems, the technical solution adopted is:

A steel pipe concrete column ring beam connection node for the foundation pit engineering of the reverse method, comprising a steel pipe concrete column constructed before the reverse method is implemented, an underground structural beam and a reinforced concrete ring beam constructed during the process of the reverse method, the underground structural beam It is connected with the concrete-filled steel pipe column through a reinforced concrete ring beam. After the reverse method is completed, the concrete-filled steel pipe column is covered with reinforced concrete to form a permanent frame column. It is characterized in that: the connection between the underground structural beam and the concrete-filled steel pipe column A column end is formed in the construction of the reverse method, and the column end is located at the lower end of the junction of the reinforced concrete ring beam and the steel pipe concrete column. After the practice is completed, the permanent frame column is the same, and the contact between the end of the column and the concrete-filled steel tube column is connected with the end-connection stud, and the end-connection stud is welded on the outer wall of the steel pipe of the concrete-filled steel tube column. The outer circumference of the steel pipe wall of the concrete-filled steel pipe column is arranged at intervals, the top elevation of the reinforced concrete ring beam is the same as the top elevation of the adjacent underground structural beam, and the bottom elevation of the reinforced concrete ring beam is lower than the bottom elevation of the adjacent underground structural beam. Elevation, the top longitudinal steel bars of the underground structural beams are bent downwards and anchored under the top steel bars of the reinforced concrete ring beams, the bottom longitudinal steel bars of the underground structural beams are bent upwards and anchored into the bottom of the reinforced concrete ring beams , located on the bottom reinforcement of the reinforced concrete ring beam.

Based on the above technical features, the concrete-filled steel pipe column is provided with studs within the range of the reinforced concrete ring beam, and the studs are arranged at intervals along the outer perimeter surface of the steel pipe of the concrete-filled steel pipe column. The arrangement of studs is beneficial to improve the shear capacity of reinforced concrete ring beams and steel tube concrete columns.

Based on the above technical features, the steel tube concrete column is provided with ring bars within the range of the reinforced concrete ring beam, and the ring bars are arranged at intervals around the steel tube surface of the steel tube concrete column. The function of the ring reinforcement is to improve the shear capacity of the reinforced concrete ring beam and the concrete-filled steel tube column. The ring reinforcement can be used together with the studs in the range of the above-mentioned reinforced concrete ring beam, or it can be used alone.

The above method has successfully solved the problem of crossing steel bars at the underground beam-column joints in the concrete-filled steel tube column reverse engineering. At the same time, through the application of measures such as column ends, ring bars and studs, it has also solved the problem of conventional reinforced concrete ring beams and steel tube concrete columns. The problem of low shear capacity.

Description of drawings

Below in conjunction with accompanying drawing and embodiment and applied construction method, the present invention will be further described.

Fig. 1 is a three-dimensional view of the concrete-filled steel tube column-beam-column joint in the reverse construction method of the present invention.

Fig. 2 is a longitudinal sectional view of the concrete-filled steel tube column-beam-column joint in the reverse construction method of the present invention.

Fig. 3 is a cross-sectional view of the concrete-filled steel tube column-beam-column joint in the upside-down construction of the present invention.

Detailed ways

As shown in Figures 1, 2 and 3, 1 is a reinforced concrete ring beam, 2 is a steel pipe concrete column, 3 is an underground structural beam constructed during the implementation of the reverse method, 4 is the end of the column constructed during the implementation of the reverse method, and 5 6 is the ring bar, 8 is the longitudinal steel bar at the top of the underground structural beam, 9 is the longitudinal steel bar at the bottom of the underground structural beam, 10 is the top steel bar of the reinforced concrete ring beam, 11 12 is the bottom steel bar of the reinforced concrete ring beam, and 12 is the stud connecting the end of the column and the joint of the steel tube concrete column. The invention can be applied to the mid-span beam-slab joint of the basement, and can also be applied to the steel pipe concrete column-beam-column joint with different beam heights on both sides or with beams on one side.

In order to avoid the problem that the top longitudinal steel bar 8 and the bottom longitudinal steel bar 9 of the underground structural beam cannot pass through the connection position between the concrete-filled steel tube column and the underground structural beam, the steel-filled steel tube concrete column adopts a method different from that of conventional reinforced concrete column-beam-column joints using reinforced ring plates. The reinforced concrete ring beam 1 is used to connect the underground structural beam 3 and the steel pipe concrete column 2, the elevation of the top of the reinforced concrete ring beam 1 is equal to the elevation of the adjacent underground structural beam 3, and the longitudinal steel bars 8 at the top of the underground structural beam 3 are bent downward and anchored There are 10 steel bars on the top of the reinforced concrete ring beam; the elevation of the bottom of the reinforced concrete ring beam 1 is lower than the bottom elevation of the adjacent underground structural beam 3, and the longitudinal steel bars 9 at the bottom of the underground structural beam 3 are bent upwards, anchored into the bottom of the reinforced concrete ring beam 1, and located in the ring Beam bottom reinforcing bar 11 on. The anchorage length is determined according to the structural requirements of the existing reinforced concrete technical specifications.

In order to solve the shear bearing capacity of the CFST column and the RC ring beam, the following measures were taken:

First, the column end 4 is added. This end is formed in the construction of the reverse method. The cross-sectional size and reinforcement are the same as the permanent frame column. After the reverse method is completed, it will be a part of the permanent frame column. The columns are connected by the end connection pegs 12 arranged on the outer wall of the steel pipe concrete column 2, and the setting of the end connection pegs 12 can increase the vertical shear bearing capacity of the nodes.

Second, the stud 5 is welded at the connection between the steel pipe of the steel pipe concrete column 2 and the reinforced concrete ring beam 1. In the reverse engineering, the steel pipe concrete column should be constructed from the ground before excavation of the foundation pit, as a construction process of the reverse method The vertical support of the above-ground structure in the middle ground. The stud 5 can be completed by welding in the factory before the construction of the steel tube concrete column, which can avoid the adverse effect of welding stress on the force of the steel tube concrete column during the reverse excavation stage.

Thirdly, the ring bars 6 are welded at the connection between the steel pipe of the steel pipe concrete column 2 and the reinforced concrete ring beam, and are arranged at intervals around the steel pipes. The ring bars 6 can also be welded in the factory before the construction of the steel pipe concrete column. In the excavation stage, the welding stress has an adverse effect on the stress of the CFST column.

The above-mentioned anti-shear measures can be used simultaneously or separately.

The specific construction method is as follows: first, the studs 5 and the ring bars 6 are welded on the outer wall of the steel pipe concrete column 2 in the factory, and then the vertical support concrete steel pipe column is formed from the ground on the construction site, and the foundation pit is excavated to the ground After the bottom elevation of structural beam 3 and the concrete-filled steel tube columns are exposed, the formwork construction of reinforced concrete ring beam 1, underground structural beam 3 and column end 4 of the concrete-filled steel tube beam-column joints is carried out, and then the reinforced concrete ring beam 1 and underground structure are bound The beam 3 and the steel bar at the end 4 of the pre-cast section column, the longitudinal steel bar 8 at the top of the underground structural beam is bent downward and anchored into the reinforced concrete ring beam 1, and the longitudinal steel bar 9 at the bottom of the underground structural beam is bent upward and anchored into the reinforced concrete ring beam 1 . Finally, the ring beam 1, the underground structural beam 3, and the concrete of the structural column end 4 are integrally poured to form a complete inverted basement structure. After the top-down construction is completed, the outer side of the concrete-filled steel tube column 2 is covered with reinforced concrete to form a permanent frame column.

The present invention can adjust the height of the reinforced concrete ring beam for different underground structure beam heights on both sides, or when there are beams on only one side of the basement side-span structure. into the reinforced concrete ring beam.

The above is a detailed introduction to a solution provided by the embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the embodiment of the present invention, there will be changes in the specific implementation manner and application scope. To sum up, the contents of this specification should not be construed as limiting the present invention, and any changes made according to the design concept of the present invention are within the scope of protection of the present invention.

Claims (3)

1. steel core concrete column ring beam connected node that is used for base pit engineering of topdown construction method, comprise the steel core concrete column (2) of constructing before contrary sequence method is implemented, underground structure beam (3) of constructing in the contrary sequence method implementation process and reinforced concrete circle beam (1), described underground structure beam (3) is connected by described reinforced concrete circle beam (1) with described steel core concrete column (2), after contrary sequence method is implemented to finish at described steel core concrete column (2) encased steel reinforced concrete, form permanent frame column, it is characterized in that: described underground structure beam (3) and described steel core concrete column (2) junction are provided with and form styletable head (4) in the reverse construction, described styletable head (4) is positioned at the positive lower end of described reinforced concrete circle beam (1) and described steel core concrete column (2) intersection, permanent frame column after the cross-sectional sizes of described styletable head (4) and arrangement of reinforcement and described contrary sequence method are implemented to finish is identical, the steel pipe contact position of described styletable head (4) and described steel core concrete column (2) is connected peg (12) with the termination and connects, described termination connects peg (12) and is welded on the outer wall of steel pipe of described steel core concrete column (2), arrange at interval along described steel core concrete column (2) steel pipe walls outer perimeter, the top mark of described reinforced concrete circle beam (1) is high identical with the top mark height that is adjacent to down structural beams, the end absolute altitude of described reinforced concrete circle beam (1) is lower than the end absolute altitude that is adjacent to down structural beams, the top longitudinal reinforcement (8) of described underground structure beam (3) is bending downwards, anchor under the described reinforced concrete circle beam top rebars (10), the bottom longitudinal reinforcement (9) of described underground structure beam (3) is bending upwards, anchor into described reinforced concrete circle beam (1) bottom, be positioned on the described reinforced concrete circle beam bottom reinforcement bars (11).

2. a kind of steel core concrete column ring beam connected node that is used for base pit engineering of topdown construction method according to claim 1, it is characterized in that described steel core concrete column (2) is provided with peg (5) in described reinforced concrete circle beam (1) scope, described peg (5) is arranged along the steel pipe outer perimeter spaced surface of described steel core concrete column (2).

3. a kind of steel core concrete column ring beam connected node that is used for base pit engineering of topdown construction method according to claim 1 and 2, it is characterized in that described steel core concrete column (2) is provided with ring muscle (6) in described reinforced concrete circle beam (1) scope, described ring muscle (6) is arranged at interval around the steel tube surface of described steel core concrete column (2).

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