High-strength and high-ductility concrete filled steel tubular column

Abstract

The invention provides a high-strength and high-ductility steel pipe concrete column which comprises a rectangular outer steel pipe and arc-shaped inner steel plates connected to each steel pipe face of the inner side of the rectangular outer steel pipe, the arc-shaped inner steel plates and the steel pipe faces of the inner side of the rectangular outer steel pipe form four closed and non-intersecting cavities, and the portion outside the inner cavities of the rectangular outer steel pipe is a core area. The core area is filled with concrete; the arc-shaped inner steel plate provides constraint on the concrete column core similar to a circular steel pipe, so that concrete in all areas in the outer steel pipe can be well restrained, meanwhile, the arc-shaped inner steel plate provides a supporting effect for the outer steel pipe, local buckling deformation of the rectangular outer steel pipe is effectively delayed, and the service life of the outer steel pipe is prolonged. Therefore, the concrete filled steel tubular column member has high strength and good ductility.

Description

Technical Field

[0001] The invention belongs to the field of building construction, and in particular relates to a high-strength and high-ductility steel tube concrete column. Background Art

[0002] Steel-concrete composite component systems are widely used in modern engineering buildings, among which concrete-filled steel tube columns (CFST) are widely used due to their superior structural performance. They eliminate the need for temporary molds when pouring concrete, thereby shortening the construction period and saving labor costs. The outer steel tube in the concrete-filled steel tube column delays the lateral expansion and damage of the concrete column core, while the concrete column core can effectively prevent the inward buckling of the outer steel tube.

[0003] Circular steel tube concrete and square steel tube concrete are the two most common cross-sectional forms at present. Circular steel tubes can provide good restraint effects for the core of concrete columns, but due to the existence of their external curved surfaces, external ring plates are usually required when connecting beams and columns. In contrast, square steel tubes can be easily connected to components due to their external planes, making square steel tube concrete columns more widely used in structures. However, at the same time, the restraint effect of square steel tubes on the core of concrete columns is not as good as that of circular steel tubes, and they are more prone to local buckling failure. When high-strength steel and high-strength concrete are used, the poor restraint effect of square steel tubes and the local buckling problem will become more prominent, greatly reducing the ductility of the composite column and hindering the application of high-strength square steel tube concrete columns.

[0004] In order to improve the structural performance of square steel tube concrete columns, there are many design methods in existing applications, such as welding stiffening ribs inside steel tubes, using stirrups to constrain the concrete column core, and inserting round steel tubes into square steel tubes. However, these methods cannot solve the problems of local buckling deformation and improving the constraint effect at the same time, and also increase the construction workload and prolong the construction period. Therefore, the development of a new type of high-strength and high-ductility square steel tube concrete column has important engineering practice significance and social and economic value. Summary of the invention

[0005] Based on this, the present invention provides a high-strength and high-ductility steel tube concrete column to overcome various defects of the square steel tube concrete column components in the prior art.

[0006] The invention discloses a high-strength and high-ductility steel tube concrete column, comprising a rectangular outer steel tube and an arc-shaped inner steel plate connected to each steel tube surface inside the rectangular outer steel tube, wherein the arc-shaped inner steel plate and the steel tube surface inside the rectangular outer steel tube form four closed cavities that do not intersect each other, and the area outside the internal cavity of the rectangular outer steel tube is a core area, which is filled with concrete.

[0007] Optionally, the arc-shaped inner steel plate is a semicircular inner steel plate.

[0008] Optionally, the arc-shaped inner steel plate is a semi-elliptical inner steel plate.

[0009] Optionally, the arc surface of the arc-shaped inner steel plate coincides with the interface between the ineffective constraint area and the effective constraint area of ​​the rectangular outer steel tube.

[0010] Optionally, the cavity formed in the rectangular outer steel tube is filled with concrete.

[0011] Optionally, the cavity is filled with concrete of the same strength as the core area.

[0012] Optionally, the cavity and the core area are filled with concrete of different strengths.

[0013] Optionally, the cavity is filled with high-strength concrete and the core area is filled with ordinary-strength concrete.

[0014] Optionally, the rectangular outer steel tube and the arc-shaped inner steel plate are made of high-strength steel.

[0015] On the other hand, the present invention also provides a construction method of the above steel tube concrete column, comprising:

[0016] Welding the arc-shaped inner steel plate to the steel sheet with the arc-shaped end portion;

[0017] The steel sheet welded with the arc-shaped inner steel plate is welded through the arc-shaped end to form a rectangular outer steel tube, the arc-shaped inner steel plate is located on the inner side of the rectangular outer steel tube, and the arc-shaped inner steel plate and the steel tube surface on the inner side of the rectangular outer steel tube form four closed and non-intersecting cavities, and the area outside the inner cavity of the rectangular outer steel tube is the core area;

[0018] Fill the core area with concrete.

[0019] Optionally, the cavity is filled with concrete.

[0020] The high-strength and high-ductility steel tube concrete column provided by the present invention has the following beneficial effects:

[0021] The arc-shaped inner steel plate and the steel tube surface on the inner side of the rectangular steel tube form a cavity, providing a new cross-sectional form of steel tube concrete column. The arc-shaped inner steel plate acts as a stiffening rib to provide good support for the outer steel tube, reduce the cross-sectional width-to-thickness ratio of the steel tube, and can effectively delay the local buckling deformation of the rectangular outer steel tube; at the same time, the arc-shaped inner steel plate can provide a similar restraint effect on concrete as a round steel tube, making up for the defect of invalid restraint areas in traditional rectangular steel tubes. On the other hand, the arc-shaped inner steel plate, as a form of internal stiffening rib, is embedded between the concrete column cores. In a fire environment, the temperature of the inner steel plate is lower than that of the outer steel tube, and has better fire resistance. When this new type of steel tube concrete column uses high-strength steel and a mixture of concretes of different strengths, it can improve the bearing capacity of the composite column while ensuring that the composite column has good ductility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 The diagram shows the ineffective constraint area and effective constraint area of ​​steel pipes with different cross-sections.

[0024] Figure 2 A three-dimensional diagram of a square steel tube concrete column provided by an embodiment of the present invention;

[0025] Figure 3 A longitudinal cross-sectional view of a square steel tube concrete column provided by an embodiment of the present invention;

[0026] Figure 4 The cross section of the square steel tube concrete column provided in the embodiment of the present invention;

[0027] Figure 5 A cross section of a square steel tube concrete column provided by another embodiment of the present invention;

[0028] Figure 6 A cross section of a rectangular concrete-filled steel tube column provided in another embodiment of the present invention;

[0029] Figure 7 The load-strain curves of concrete-filled steel tube columns under different concrete filling methods;

[0030] Figure 8 A cross section of a rectangular concrete-filled steel tube column provided in another embodiment of the present invention;

[0031] Fig. 9 The present invention provides a schematic diagram of the process of processing the steel tube portion of a square steel tube concrete column according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] According to the calculations and proofs of relevant studies, Figure 1As shown in the figure, there are invalid constraint areas inside the commonly used rectangular steel tubes and polygonal steel tube concrete, while the inside of the circular steel tube concrete is all effective areas. The invalid constraint area is close to the inner side of the steel tube. From the cross-section point of view, the interface between the invalid constraint area and the effective constraint area in the rectangular steel tube concrete column is generated in the form of a quadratic parabola with an initial tangent slope of 45 degrees. The existence of these invalid constraint areas makes the rectangular steel tube and polygonal steel tube have poor constraint effect on the concrete column core. Compared with circular steel tubes, the planes of rectangular and polygonal steel tubes are more prone to local buckling, resulting in failure and damage of composite columns. When high-strength steel and high-strength concrete are used to increase the bearing capacity, the above-mentioned problems of poor constraint effect and local buckling will become more prominent, the brittleness of the composite column will increase, and the ductility performance will be further reduced.

[0034] Based on the defects of the existing design, the present invention provides a steel tube concrete column with a new cross-section, which is explained one by one through the following embodiments.

[0035] like Figure 2 to Figure 4 As shown, taking a square steel tube as an example, the high-strength and high-ductility steel tube concrete column provided by the present invention includes a rectangular outer steel tube 1 and an arc-shaped inner steel plate 2 connected to each steel tube surface on the inner side of the rectangular outer steel tube, the arc-shaped inner steel plate 2 and the steel tube surface on the inner side of the rectangular outer steel tube 1 form four closed and non-intersecting cavities 3, the outside of the cavity 3 in the rectangular outer steel tube 1 is a core area 4, and the cavity 3 and the core area 4 are filled with concrete.

[0036] The arc-shaped inner steel plate can provide constraints similar to those of a round steel tube, and has a good constraint effect on the concrete filled in the cavity, turning the invalid constraint area in the original rectangular steel tube concrete column into an effective constraint area; at the same time, the core area is the effective constraint area in the original rectangular steel tube concrete column, so the concrete in all the filling areas in the cross section of this new steel tube concrete column is in a good constraint state. On the other hand, the arc-shaped inner steel plate can also be regarded as the internal longitudinal stiffening rib of the outer steel tube, providing support for the outer steel tube, reducing its cross-sectional width-to-thickness ratio, and effectively delaying the local buckling deformation of the outer steel tube. In a fire environment, the arc-shaped inner steel plate embedded in the concrete heats up slowly due to protection, which improves the fire resistance of the composite column. The outer steel tube and the arc-shaped inner steel plate of the new steel tube concrete column are made of high-strength steel, and the cavity and the core area are filled with high-strength concrete and ordinary strength concrete respectively. While increasing the bearing capacity of the composite column, it can improve its deformation capacity and ductility, and realize the design of high-strength and high-ductility steel tube concrete columns.

[0037] by Figure 4 For example, the arc inner steel plate can be a semicircular steel plate, and in possible designs it can also be as follows Figure 5 As for the semi-elliptical steel plate shown, it can be understood by those skilled in the art that the diameter or the major and minor axes of the arc-shaped inner steel plate can be adjusted according to the width-to-thickness ratio of the outer steel tube to obtain a better overall restraint effect and anti-local buckling effect.

[0038] In a possible design, the arc edge design of the arc inner steel plate can also coincide with the interface between the invalid constraint area and the effective constraint area in the traditional rectangular steel tube, such as Figure 1 (a) and Figure 1 (b), that is, from the cross-sectional form, the projected edge of the arc-shaped inner steel plate coincides with the interface between the two areas. This design makes the original ineffective constraint area in the rectangular steel tube subject to constraints similar to those of the circular steel tube, and the concrete column core on the entire cross-section is effectively constrained, which has better compressive performance than the traditional rectangular steel tube concrete column.

[0039] In possible designs, for rectangular steel tube concrete columns with unequal long and short sides, the curved inner steel plate can be partially semicircular and partially semi-elliptical, such as Figure 6 As shown, all inner steel plates may also use the same arc shape, and the present invention does not further limit this.

[0040] Those skilled in the art should understand that the rectangular steel tube referred to in the present invention is not limited to square steel tubes, but also includes steel tubes with rectangular cross-sections. According to the technical concept of the present invention, in further designs, such designs can also be applied to other polygonal steel tubes, such as pentagons, hexagons, octagons, etc. As long as the arc-shaped inner steel plate and the steel tube surface on the inner side of the polygon form a closed and non-intersecting cavity, they all fall within the scope of the present invention. Similarly, when applied to other polygonal steel tubes, the design of the arc-shaped inner steel plate can be semicircular or semi-elliptical, or it can be the interface that overlaps the invalid constraint area and the effective constraint area of ​​the polygon, such as Figure 1 (c) and Figure 1 (d).

[0041] The concrete filled in the core area of ​​the rectangular outer steel tube and the concrete filled in the cavity can be of the same strength or different strengths. For example, the cavity is filled with ultra-high strength concrete (such as C90 / 105) and the core area is filled with ordinary strength concrete (such as C50 / 60). The mixing of concretes of different strengths can overcome the problem of poor ductility caused by the brittleness of ultra-high strength concrete, and can also improve the load capacity of steel tube concrete columns. Figure 7 The load-strain curves of steel tube concrete columns with different column cores are shown. The load capacity of traditional steel tube concrete columns filled only with ordinary strength concrete is poor, and the load capacity of traditional steel tube concrete columns filled only with ultra-high strength concrete decreases significantly after brittle failure. The new steel tube concrete column provided in the embodiment of the present invention has a separated cavity and core area, which can realize the mixed use of concrete of different strengths. In this case, the new steel tube concrete column has good load capacity and ductility at the same time, and the combined column has better toughness.

[0042] In a possible design, the cavity may not be filled with concrete to reduce the overall weight of the component. The hollow cavity can be used to lay wires or drainage pipes, or it can be partially filled with concrete. Figure 8 shown.

[0043] In a possible design, the cross-sectional form of the cavity formed by the arc-shaped inner steel plate and the rectangular outer steel tube proposed in the present invention can also be used as a beam component. When used as a beam component, the core area inside the steel tube is filled with ordinary strength concrete, and the upper part of the steel tube is under pressure, so the cavity at the upper part is filled with ultra-high strength concrete. The lower part of the steel tube is under tension, so the cavity at the lower part can remain hollow, such as Figure 8 shown.

[0044] In a possible design, both the rectangular outer steel tube and the curved inner steel plate use high-strength steel to provide better column strength.

[0045] like Fig. 9 As shown, an embodiment of the present invention also provides a construction method of the steel tube concrete column shown in the above embodiments, which is similar to the traditional construction method, and the outer steel tube and the arc-shaped inner steel plate are completed by cold forming and welding processes.

[0046] Specifically, since the arc-shaped inner steel plate needs to be located inside the rectangular outer steel tube, the cold-formed arc-shaped inner steel plate is first welded to a steel sheet with an arc-shaped end, and then the steel sheet welded with the arc-shaped inner steel plate is welded through the arc-shaped end to form a rectangular steel tube. The arc-shaped inner steel plate is located on the inner side of the rectangular steel tube, and the arc-shaped inner steel plate and the steel tube surface on the inner side of the rectangular steel tube form four closed and non-intersecting cavities. The area outside the internal cavity of the rectangular outer steel tube is the core area, and concrete is poured in the cavity area and the core area.

[0047] In order to prevent stress concentration and premature fracture, welding should be avoided at the corners when splicing rectangular external steel pipes.

[0048] In order to simplify the pouring procedure and improve construction efficiency, the cavity can be filled with concrete in the factory first, and then the concrete in other areas of the outer steel pipe can be filled at the construction site.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength and high-ductility steel tube concrete column, characterized in that: It includes a rectangular outer steel pipe and an arc-shaped inner steel plate connected to each steel pipe surface on the inner side of the rectangular outer steel pipe. The arc-shaped inner steel plate and the steel pipe surface on the inner side of the rectangular outer steel pipe form four closed and non-intersecting cavities. The area outside the inner cavity of the rectangular outer steel pipe is a core area, and the core area is filled with concrete.

2. The high-strength and high-ductility steel tube concrete column according to claim 1, characterized in that: The arc-shaped inner steel plate is a semicircular inner steel plate.

3. The high-strength and high-ductility steel tube concrete column according to claim 1, characterized in that: The arc-shaped inner steel plate is a semi-elliptical inner steel plate.

4. The high-strength and high-ductility steel tube concrete column according to claim 1, characterized in that: The arc surface of the arc-shaped inner steel plate coincides with the interface between the ineffective constraint area and the effective constraint area of ​​the rectangular outer steel tube.

5. The high-strength and high-ductility steel tube concrete column according to claim 1, characterized in that: The cavity is filled with concrete.

6. The high-strength and high-ductility steel tube concrete column according to claim 5, characterized in that: The cavity is filled with concrete having the same strength as the core area.

7. The high-strength and high-ductility steel tube concrete column according to claim 5, characterized in that: The cavity and the core area are filled with concrete of different strengths.

8. The high-strength and high-ductility steel tube concrete column according to claim 5 or 7, characterized in that: The cavity is filled with high-strength concrete, and the core area is filled with ordinary-strength concrete.

9. The high-strength and high-ductility steel tube concrete column according to claim 1, characterized in that: The rectangular outer steel pipe and the arc-shaped inner steel plate are made of high-strength steel.

10. A construction method for a high-strength and high-ductility steel tube concrete column as claimed in any one of claims 1 to 9, characterized in that: include: Welding the arc-shaped inner steel plate to the steel sheet with the arc-shaped end portion; The steel sheet welded with the arc-shaped inner steel plate is welded through the arc-shaped end to form a rectangular outer steel tube, the arc-shaped inner steel plate is located on the inner side of the rectangular outer steel tube, and the arc-shaped inner steel plate and the steel tube surface on the inner side of the rectangular outer steel tube form four closed and non-intersecting cavities, and the area outside the inner cavity of the rectangular outer steel tube is the core area; Concrete is poured in the core area.

11. The construction method according to claim 10, characterized in that: The construction method also includes: The cavity is filled with concrete.

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