Connection between concrete-filled steel pipe column and steel beam

Abstract

To provide a junction between a concrete-filled steel pipe column and a steel beam capable of, in the column-beam junction of a CFT structure, freely controlling the performance of the CFT columns and the thickness-to-width ratio of the column steel pipe.SOLUTION: A junction between a concrete-filled steel pipe column and a steel beam 2 according to the present invention includes: a concrete-filled steel pipe column, where concrete is poured into an interior of a steel pipe column 1; upper and lower flanges 2a and 2c; and a web 2b. In the junction where the steel beam 2 connects to the steel pipe column 1, a diaphragm 3 is placed at a position where the upper and lower flanges 2a and 2c of the steel beam 2 are connected to the concrete-filled steel pipe column, and multiple rod-shaped protrusions are provided on an inner surface of the steel pipe column 1. By providing the rod-shaped protrusions on the inner surface of the steel pipe column 1, a vertical force from steel beam 2 can be transmitted to the steel pipe column 1, thereby, integrity between the steel pipe column 1 and the concrete core is improved. Furthermore, performance of a CFT column is improved while the apparent thickness-to-width ratio of the steel pipe in the column decreases.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a column-beam joint in a concrete-filled steel pipe structure (hereinafter referred to as a CFT structure), particularly to the structure of the joint when a diaphragm is provided at the joint between a concrete-filled steel pipe column and a steel beam. [Background technology]

[0002] One of the factors that determines the performance of CFT columns is the width-thickness ratio (b / t) of the steel column pipe. The smaller the width-thickness ratio of the steel column pipe, the higher the performance of the CFT column, but the thicker the pipe, which tends to increase costs. In particular, for CFT columns with rectangular cross sections, the thickness of the steel pipe must be designed to achieve the specified width-thickness ratio using one of the following methods.

[0003] For example, when manufacturing steel column pipes as a welded four-sided box made by welding four steel plates, the long and short sides can be different thicknesses as long as the width-thickness ratio is above a certain level. However, if the long and short sides are different thicknesses, costs tend to increase compared to when the long and short sides are the same thickness. In addition, since welded four-sided boxes require a large amount of welding, they are more expensive than press-formed square steel pipes.

[0004] In addition, when manufacturing steel columns using press-formed rectangular steel pipes, the thickness of the long and short sides is the same, so the thickness of the steel pipe must be designed so that the long side has a predetermined width-thickness ratio. In this case, the steel pipe tends to be excessively thick on the short side, making rational design difficult.

[0005] In CFT structures, in the case of through diaphragms or internal diaphragms, the vertical force from the beam can be transmitted to both the column steel pipe and the column concrete via the diaphragm, but in the case of external diaphragms, the vertical force from the beam can only be transmitted to the column steel pipe, so it is necessary to consider a method of transmitting the vertical force from the beam by providing protrusions on the inner surface of the column steel pipe.

[0006] Patent Documents 1 and 2, for example, describe inventions relating to CFT structures in which protrusions are provided on the inner surface of steel column pipes.

[0007] Patent document 1 describes a joint structure for a steel pipe concrete member, in which a plurality of studs are implanted at intervals on the inner surface of the steel pipe column member where the upper and lower flanges of the steel beam abut, and the steel pipe column member is filled with concrete to bury the studs.

[0008] Patent Document 2 describes a construction structure for a panel zone where a steel pipe column, with concrete and mortar filled in the steel pipe, intersects with a beam, in which studs are provided inside the steel pipe of the steel pipe column in a manner that corresponds to each beam. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 05-321355 [Patent Document 2] Japanese Patent Application Publication No. 01-318631 Summary of the Invention [Problem to be solved by the invention]

[0010] The invention described in Patent Document 1 has multiple studs installed on the inner surface of the steel pipe column member where the upper and lower flanges of the steel beam meet, but if there are too many studs, they can become intertwined and make it difficult to fill with concrete.The invention described in Patent Document 2 has studs installed only within the column-beam joint, and not in the column, so it does not contribute to improving the performance of the column.

[0011] The purpose of the present invention is to provide a joint between a concrete-filled steel pipe column and a steel beam in which the performance of the CFT column and the width-thickness ratio of the column steel pipe can be freely controlled by providing studs in the column steel pipe at the column-beam joint of a CFT structure. [Means for solving the problem]

[0012] The joint between a concrete-filled steel pipe column and a steel beam according to the present invention is characterized in that, at the joint between a concrete-filled steel pipe column in which concrete is filled inside the column steel pipe and a steel beam consisting of upper and lower flanges and a web and joined to the column steel pipe, a diaphragm is provided at the position where the upper flange and lower flange of the steel beam are connected to the concrete-filled steel pipe column, and a plurality of rod-shaped protrusions are provided on the inner surface of the column steel pipe.

[0013] Generally, the lower floors of a building require a larger thickness for their steel columns because they support more. On the other hand, the upper floors require fewer supports, so the thickness of the steel columns on those floors can be smaller. The applicant has devised a method to improve the width-thickness ratio by providing rod-shaped protrusions on the inner surface of the steel columns, thereby reducing the thickness of the steel columns on the lower floors compared to conventional methods.

[0014] In this invention, by providing rod-shaped protrusions on the inner surface of the steel column pipe, the vertical force from the beam can be transmitted to the steel column pipe, improving the integrity of the steel column pipe and the column concrete. In addition, the width-thickness ratio of the steel column pipe appears to be smaller, improving the performance of the CFT column.

[0015] The cross-sectional shapes of the steel column pipes covered are circular, oval, square, and rectangular. The rod-shaped protrusions placed on each surface may be one or more. The diaphragm may be a through diaphragm, an inner diaphragm, or an outer diaphragm.

[0016] In addition, in the joint between a concrete-filled steel pipe column and a steel beam of the present invention, the cross section of the steel pipe column and the shape of the diaphragm are preferably rectangular. The cross section of the steel pipe column in the present invention is not particularly limited and may be circular, oval, square, rectangular, or other shapes. However, when the steel pipe column has a rectangular cross section, the performance of the CFT column and the width-thickness ratio of the steel pipe column can be freely controlled by the arrangement of the rod-shaped protrusions, so the thickness of the steel pipe on the long and short sides can be made the same, preventing costs from increasing.

[0017] In the joint between a concrete-filled steel pipe column and a steel beam of the present invention, when the cross section of the steel pipe column and the shape of the diaphragm are rectangular, the rod-shaped protrusions are preferably provided on the long sides of the rectangular cross section of the steel pipe column and the diaphragm. The rod-shaped protrusions may be arranged horizontally on all four sides, or only on the long sides. By arranging the rod-shaped protrusions only on the long sides, the thickness of the steel pipe on the long and short sides can be made the same, thereby suppressing cost increases.

[0018] At the joint between a concrete-filled steel pipe column, in which concrete is filled inside the column steel pipe, and a steel beam consisting of upper and lower flanges and webs and joined to the column steel pipe, a thicker-walled joint steel pipe than the upper and lower column steel pipes is interposed in the section where the end of the steel beam is joined to the concrete-filled steel pipe column, and multiple rod-shaped protrusions are provided on the inner surface of the column steel pipe.

[0019] By inserting a thicker steel pipe between the concrete-filled steel pipe column and the steel beam at the section where the end of the beam is joined, a diaphragm is no longer necessary. By providing rod-shaped protrusions on the inner surface of the steel pipe, the vertical force from the beam can be transmitted to the steel pipe, improving the integrity of the steel pipe and the concrete in the column. Furthermore, the apparent width-thickness ratio of the steel pipe is reduced, improving the performance of the CFT column.

[0020] Furthermore, in the joint between a concrete-filled steel pipe column and a steel beam of the present invention, the cross sections of the column steel pipe and the joint steel pipe are preferably rectangular. The cross-sectional shapes of the column steel pipe and the joint steel pipe in the present invention are not particularly limited and may be circular, oval, square, rectangular, or the like. However, when the column steel pipe has a rectangular cross section, the performance of the CFT column and the width-thickness ratio of the column steel pipe can be freely controlled by the arrangement of the rod-shaped protrusions, so the thickness of the steel pipe on the long and short sides can be made the same, preventing costs from increasing.

[0021] In the joint between a concrete-filled steel pipe column and a steel beam of the present invention, when the cross section of the steel pipe column and the cross section of the joint steel pipe are rectangular, the rod-shaped protrusions are preferably provided on the long sides of the rectangular cross sections of the column steel pipe and the joint steel pipe. The rod-shaped protrusions may be arranged horizontally on all four sides, or only on the long sides. By arranging the rod-shaped protrusions only on the long sides, the thickness of the steel pipe on the long and short sides can be made the same, thereby suppressing cost increases.

[0022] In the joint between the concrete-filled steel pipe column and the steel beam of the present invention, the rod-shaped protrusions may be provided on the inner surface of the steel pipe column at the base of the upper floor and at the head of the lower floor. The rod-shaped protrusions may be vertically arranged in a dispersed manner over the entire steel pipe column, or may be concentrated at the base of the steel pipe column at the base of the upper floor.

[0023] The rod-shaped protrusions may also be provided on the inner surface of the steel pipe column at the position of the column head of the lower floor. The rod-shaped protrusions provided on the steel pipe column may be concentrated not only at the column base of the upper floor but also at the column head of the lower floor. Alternatively, the rod-shaped protrusions may be provided over the entire steel pipe column, with more protrusions at the column head of the upper floor and the column base of the lower floor.

[0024] In the joint between the concrete-filled steel pipe column and the steel beam of the present invention, the rod-shaped protrusion is preferably a stud or a steel rod with a thread. The rod-shaped protrusion used in the present invention is a rod-shaped protrusion that can be attached to the steel pipe column and has sufficient strength and durability, and headed studs, threaded studs, full threads, half threads, etc. can be used.

[0025] In the joint between a concrete-filled steel pipe column and a steel beam of the present invention, if the rod-shaped projection is a steel rod having a thread, it may be attached to a threaded hole provided in the steel pipe. If the rod-shaped projection is a stud, it may be attached to the steel pipe by welding, for example, but if it is a threaded steel rod, instead of welding, it may be attached by pre-forming a threaded hole in the steel pipe, passing the threaded steel rod from the outside to the inside of the steel pipe, and tightening the screw to secure it.

[0026] Furthermore, when the rod-shaped projection is a steel rod having a threaded portion, it may be attached to a nut provided on the inner or outer surface of a drilled hole provided in the steel column. Alternatively, a drilled hole without a thread instead of a tapped hole may be provided in the steel column, and a nut or the like may be provided on the inner or outer surface of the drilled hole, and a steel rod having a threaded portion may be attached and fixed. [Effects of the Invention]

[0027] Since the present invention is a joint between a concrete-filled steel pipe column and a steel beam as described above, it has the following effects. (1) By providing studs on the inner surface of the CFT column, the integrity of the column steel pipe and the column concrete is improved, the width-thickness ratio of the column steel pipe appears to be smaller, and the performance of the CFT column is improved. (2) In rectangular cross-section CFT columns, the performance of the CFT column and the width-thickness ratio of the column steel pipe can be freely controlled by arranging the studs, so the thickness of the steel pipe on the long and short sides can be made the same, which helps prevent costs from increasing. (3) By providing studs on the inner surface of the CFT column, the studs become inner protrusions, and vertical forces from the beams and steel pipe columns can be transmitted to the column concrete. [Brief explanation of the drawings]

[0028] [Figure 1] 1 shows an embodiment in which a diaphragm is used at the joint between a concrete-filled steel pipe column and a steel beam according to the present invention, where (a) is a longitudinal cross-sectional view and (b) is a plan view. [Figure 2] As another embodiment of the joint between a concrete-filled steel pipe column and a steel beam according to the present invention, the cross section of the column steel pipe and diaphragm is shown to be rectangular, where (a) is a cross section when there are six studs on the same plane, and (b) is a cross section when there are two studs. [Figure 3] FIG. 1 is a longitudinal cross-sectional view showing an embodiment in which a thick-walled joint steel pipe is used at the joint between a concrete-filled steel pipe column and a steel beam according to the present invention. [Figure 4]1A and 1B are explanatory diagrams showing the installation method of rod-shaped protrusions in the present invention, in which (a) shows a stud attached by welding, (b) shows a fully threaded bolt fixed to a screw hole, (c) shows a fully threaded bolt fixed to a nut provided on the outside of a CFT steel column pipe, and (d) shows a fully threaded bolt fixed to a nut provided inside a CFT steel column pipe. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0030] FIG. 1 shows one embodiment of the joint between a concrete-filled steel pipe column and a steel beam 2 according to the present invention, with (a) being a longitudinal cross-sectional view and (b) being a plan view. A flat diaphragm 3 is provided at the position where the upper flange 2a and lower flange 2c of the steel column pipe 1 and the steel beam 2 join. In this embodiment, the cross sections of the steel column pipe 1 and the diaphragm 3 are square. The diaphragm 3 has a concrete pouring hole 3a in the center and air vent holes 3b at the four corners.

[0031] A stud 4 is provided on the inner surface of the steel column pipe 1 above the diaphragm 3 to which the upper flange 2a of the steel beam 2 is connected. Similarly, a stud 4 is also provided below the diaphragm 3 to which the lower flange 2c of the steel beam 2 is connected. In this example, the studs 4 are arranged one on each side of the steel column pipe 1, in four rows in the height direction.

[0032] By providing studs 4 on the inner surface of the steel column pipe 1, the integrity of the steel column pipe 1 and the column concrete is improved. If the studs 4 are provided above and below the diaphragm 3 as shown in Figure 1, by providing the studs 4 near the diaphragm 3, the steel column pipe 1 and steel beam 2 can be connected more firmly.

[0033] In Figure 1, the cross-sectional shapes of the steel column pipe 1 and diaphragm 3 of the CFT column are shown as square, but they may also be circular, elliptical, or rectangular, and the cross-sectional shape is not particularly limited. Furthermore, the number of studs 4 is also not particularly limited.

[0034] Figure 2 shows another embodiment in which the steel column pipe 1 and diaphragm 3 have rectangular cross sections, with (a) showing three diaphragms arranged on the same plane on each long side of the rectangle, and (b) showing one diaphragm arranged on each side. When the cross section of the diaphragm 3 is rectangular, the distance from the concrete pouring hole 3a of the diaphragm 3 to the long side is short, and in some cases the thickness of the long side must be increased. However, by providing studs on the long side, the studs work effectively, making it possible to make the thickness of the long side and short side the same, and also suppressing costs.

[0035] When the cross section of the column steel pipe 1 and the diaphragm 3 is rectangular, the horizontal arrangement of the studs 4 can be either on the long side only or on all four sides. There can be one or more studs on each side.

[0036] Furthermore, Figure 1 shows an example in which the studs 4 are placed near the diaphragm 3, but various patterns can be considered for the placement and number of studs, such as concentrating them at the base of the upper floor column or the head of the lower floor column, distributing them throughout the entire column steel pipe, or placing them throughout the entire column steel pipe as well as at the base of the upper floor column or the head of the lower floor column.

[0037] Fig. 3 shows an embodiment of the present invention in which a thick-walled steel joint pipe 5 is used at the joint between a concrete-filled steel pipe column and a steel beam 2, and multiple studs 4 are provided above and below the steel joint pipe 5. In this example, the studs 4 are arranged in three rows in the height direction, with three studs on each side of the steel column pipe 1.

[0038] By providing a thick-walled joint steel pipe 5, a diaphragm is not required, making it easier to fill concrete into the column steel pipe 1. In addition, by providing studs 4 on the inner surface of the column steel pipe 1 above and below the joint steel pipe 5, the integrity of the column steel pipe 1 and the column concrete is improved, making it possible to more firmly connect the column steel pipe 1 and the steel beam 2.

[0039] 4A and 4B are explanatory diagrams showing a method for installing rod-shaped protrusions in accordance with the present invention. (a) shows a stud 4 attached by welding to the inside of a CFT steel pipe column 1. (b) shows a CFT steel pipe column 1 with a threaded hole 8 formed therein, and a fully threaded bolt 7 passing through the threaded hole 8 from the outside of the CFT steel pipe column 1 to secure it in place.

[0040] (c) shows a CFT steel column 1 with a drilled hole 9 without a thread, and a fully threaded bolt 7 is inserted into a nut 10 provided on the outside of the CFT steel column 1 from the outside of the CFT steel column 1 to fix it in place. In (d), an unthreaded drilled hole 9 is provided in the CFT steel column 1, and a fully threaded bolt 7 is passed through from the outside of the CFT steel column 1 and fixed to a nut 10 provided inside the CFT steel column 1.

[0041] FIG. 4 shows an embodiment in which a headed stud 4 and a fully threaded bolt 7 are used as the rod-shaped protrusions in the present invention, but other options, such as a threaded stud or a partially threaded bolt, can also be used as long as they are securely attached to the CFT steel pipe column 1 using means such as welding 6, nuts 10, screw holes 8, or drilled holes 9. [Explanation of symbols]

[0042] 1...CFT column steel pipe 2...Steel beam 2a...Upper flange 2b…Web 2c...Bottom flange 3...Diaphragm 3a...Concrete pouring hole 3b...Air vent hole 4...Stud 5…Joint steel pipe 6...Welded section 7...Fully threaded bolt 8...Screw hole 9...Drilled hole (hole without thread) 10...Nut

Claims

1. A joint between a concrete-filled steel pipe column, in which concrete is filled inside the column steel pipe, and a steel beam consisting of upper and lower flanges and a web and joined to the column steel pipe, characterized in that a diaphragm is provided at the position where the upper flange and lower flange of the steel beam are connected to the concrete-filled steel pipe column, the cross section of the diaphragm is a rectangular cross section composed of short sides and long sides, and a plurality of rod-shaped protrusions are provided only on the inner surface of the column steel pipe on the long side of the rectangular cross section of the diaphragm, and no rod-shaped protrusions are provided on the inner surface of the column steel pipe on the short side of the rectangular cross section of the diaphragm.

2. 2. The joint between a concrete-filled steel pipe column and a steel beam according to claim 1, wherein the cross section of the column steel pipe is rectangular.

3. 3. The joint between a concrete-filled steel pipe column and a steel beam according to claim 2, wherein the rod-shaped protrusion is provided on the long side of the rectangular cross section of the column steel pipe.

4. 2. The joint between a concrete-filled steel pipe column and a steel beam according to claim 1, wherein the rod-shaped protrusions are provided on the inner surface of the column base of the steel pipe on the upper floor and the column head of the steel pipe on the lower floor.

5. 2. The joint between a concrete-filled steel pipe column and a steel beam according to claim 1, wherein the rod-shaped protrusion is a stud or a steel rod having a threaded portion.

6. 6. The joint between a concrete-filled steel pipe column and a steel beam according to claim 5, wherein the rod-shaped protrusion is a steel rod having a threaded portion, and is adapted to be attached to a threaded hole provided in the column steel pipe.

7. 6. The joint between a concrete-filled steel pipe column and a steel beam according to claim 5, wherein the rod-shaped projection is a steel rod having a threaded portion, and is adapted to be attached to a nut provided on the inner or outer surface of the column steel pipe in a drilled hole provided in the column steel pipe.

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