JP7487018B2 - Pillar and beam joint structure - Google Patents

Description

The present invention relates to a joint structure between a pillar and a beam.

A joint structure between a concrete-filled steel pipe (CFT) column, in which reinforcing bars and concrete are filled inside the steel pipe, and a steel-framed (S) beam has been known.

Patent document 1 proposes a beam penetration type of joint in which a recess (cutout portion) is provided on the side of the column, and the end of the beam is inserted into the recess to reach the inside of the column.

Patent document 2 proposes an external diaphragm type in which an external diaphragm is welded to the outer surface of the column, and then the external diaphragm is welded to the flange of the beam to join the column and beam.

By using a circular external diaphragm that forms a circular ring in plan view, it is possible to plan a more efficient structure that fits in with exterior walls, etc., and to simplify the connection details of the diagonal beams, compared to using a rectangular external diaphragm that forms a rectangular ring in plan view.

The upper and lower columns are joined by main reinforcement bars (connecting rebars) placed inside the steel pipes and filled with concrete, and the edges of the upper and lower steel pipes are cut.

JP 2016-142062 A JP 2017-160754 A

However, circular external diaphragms have problems in that they are more likely to deform inward and outward from the plate surface when resisting tensile forces from beams than rectangular external diaphragms, and columns can slip out of beam-column joints, where the stress state is complex, leading to a decrease in the rigidity of the frame.

The present invention was made in consideration of the above circumstances, and provides a joint structure between columns and beams that can increase the rigidity of the structure.

In order to achieve the above object, the present invention employs the following means.
That is, the joint structure between a column and a beam according to the present invention is a joint structure between a concrete-filled steel pipe column having a cylindrical steel pipe extending in the vertical direction, main reinforcement arranged inside the steel pipe and extending in the vertical direction, and a concrete portion filled inside the steel pipe, and a beam made of H-shaped steel, the joint structure comprising: an upper diaphragm and a lower diaphragm that are provided on the outer surface of the steel pipe and have a circular outer shape in a plan view, and are joined to the upper and lower flanges of the beam; and a plurality of cotters that protrude inward from the inner surface of the steel pipe, and the column is provided with: At least two of the beams are arranged orthogonally, a line connecting the center of the steel pipe and the extension direction of the beam in a plan view is a first virtual line, and a line extending from the center of the steel pipe to the middle of the two orthogonal first virtual lines in a plan view is a second virtual line, the cotters are arranged on the second virtual line , the cotters are arranged at four locations equally spaced circumferentially and in three rows above and below, and the cotters are provided at a height position directly below the upper diaphragm, a height position directly above the lower diaphragm, and an intermediate position between them.

In the column-beam joint structure constructed in this way, multiple cotters are provided that protrude inward from the inner surface of the steel pipe. The cotters are fixed to the concrete, improving the adhesion between the steel pipe and the concrete, thereby increasing the rigidity of the frame.
In addition, a beam is joined to the steel pipe on a first imaginary line, and a cotter is provided on a second imaginary line between the first imaginary lines that cross at right angles, thereby improving the anchorage of the steel pipe to the concrete portion near the second imaginary line (the portion not joined to the beam), thereby reinforcing the rigidity in the column axial direction.

The column-beam joint structure according to the present invention is a joint structure between a concrete-filled steel pipe column and an H-shaped steel beam, the joint structure having a steel pipe extending vertically and formed into a cylindrical shape, main reinforcement arranged inside the steel pipe and extending vertically, and concrete filled inside the steel pipe, and is characterized by having upper and lower diaphragms that are provided on the outer surface of the steel pipe and have a circular outer shape in a plan view and are joined to the upper and lower flanges of the beam, and stiffening parts provided on at least one of the upper and lower parts of the upper and lower diaphragms.

In a column-beam joint structure configured in this way, the stiffening parts provided on at least one of the upper and lower parts of the upper and lower diaphragms reinforce the tensile rigidity in the beam tension direction, thereby increasing the rigidity of the frame.

In addition, in the column-beam joint structure of the present invention, the stiffening portion may be arranged on a line connecting the center of the steel pipe and the extension direction of the beam.

In a column-beam joint structure constructed in this way, the stiffening portion is positioned on a line connecting the center of the steel pipe and the extension direction of the beam, thereby suppressing damage to the upper and lower diaphragms near the yield line that is generally assumed (in guidelines, etc.) when designing the upper and lower diaphragms.

The column-beam joint structure of the present invention can increase the rigidity of the structure.

1A is a horizontal cross-sectional view of a joint structure between a column and a beam in accordance with a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of line AA of FIG. 5A is a horizontal cross-sectional view showing a joint structure between a column and a beam in accordance with a second embodiment of the present invention, and FIG. 5B is a cross-sectional view along line BB of FIG. 5A. 13 shows the results of an analysis confirming the effect of the stiffening portion in the column-beam joint structure relating to the second embodiment of the present invention.

First Embodiment
A joint structure between a column and a beam according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a joint structure between a column and a beam according to a first embodiment of the present invention, where (a) is a horizontal cross-sectional view and (b) is a cross-sectional view taken along line AA of (a).
As shown in Fig. 1, in a column-beam joint structure 100 of this embodiment, a beam 1 of steel frame construction is joined to a column 2 of concrete-filled steel pipe construction. In this embodiment, four beams 1 are disposed perpendicularly to the column 2 in a plan view. The number of beams 1 can be set appropriately.

Each beam 1 is made of H-shaped steel. The beam 1 has an upper flange 11, a lower flange 12, and a web 13.

The upper flange 11 and the lower flange 12 are arranged at a distance from each other in the vertical direction. The upper flange 11 and the lower flange 12 are formed in a plate shape. The plate surfaces of the upper flange 11 and the lower flange 12 are arranged so as to be aligned along a horizontal plane.

The web 13 connects the upper flange 11 and the lower flange 12. The web 13 is formed in a plate shape. The plate surface of the web 13 is arranged along a vertical plane.

The column 2 has a steel pipe 21, multiple main reinforcements 22, and a concrete section 23. The steel pipe 21 is formed into a cylindrical shape with its axis aligned in the vertical direction. The steel pipe 21 has a steel pipe body 21b arranged above and below the beam 1, and a cover plate 21c arranged at a height corresponding to the beam 1. Both the steel pipe body 21b and the cover plate 21c are formed into a cylindrical shape with its axis aligned in the vertical direction. The steel pipe body 21b and the cover plate 21c are joined together in a metal-to-metal manner without welding.

The main reinforcements 22 are arranged along the inside of the steel pipe 21. The main reinforcements 22 are arranged at intervals in the circumferential direction. The main reinforcements 22 extend in the vertical direction. In this embodiment, 24 main reinforcements 22 are arranged, but the number of main reinforcements 22 can be set appropriately. The concrete portion 23 is filled inside the steel pipe 21. The main reinforcements 22 are fixed to the concrete portion 23.

The column-beam joint structure 100 includes an upper diaphragm 31, a lower diaphragm 32, and a number of cotters 33.

The upper diaphragm 31 and the lower diaphragm 32 have the function of transmitting a load from the beam 1 to the column 2. The upper diaphragm 31 and the lower diaphragm 32 are provided so as to protrude radially outward from the outer surface 21a of the steel pipe 21. The upper diaphragm 31 and the lower diaphragm 32 are joined to the steel pipe 21 by welding or the like. In this embodiment, the upper diaphragm 31 and the lower diaphragm 32 are joined between the steel pipe body 21b and the cover plate 21c.

The upper diaphragm 31 is positioned at approximately the same height as the upper flange 11 of the beam 1. The thickness of the upper diaphragm 31 is slightly greater than the thickness of the upper flange 11. The upper diaphragm 31 is joined to the upper flange 11 by welding or the like.

The lower diaphragm 32 is positioned at approximately the same height as the lower flange 12 of the beam 1. The thickness of the lower diaphragm 32 is slightly greater than the thickness of the lower flange 12. The lower diaphragm 32 is joined to the lower flange 12 by welding or the like.

The upper diaphragm 31 and the lower diaphragm 32 are formed in the shape of an annular plate having a predetermined thickness in the vertical direction. As shown in FIG. 1(a), the outer peripheral surfaces 30a of the upper diaphragm 31 and the lower diaphragm 32 are substantially circular. The portions 30b of the outer peripheral surfaces of the upper diaphragm 31 and the lower diaphragm 32 that are joined to the upper flange 11 and the lower flange 12 are linear in shape corresponding to the end faces of the upper flange 11 and the lower flange 12.

The cotter 33 is provided so as to protrude radially inward from the inner surface 21d of the cover plate 21c of the steel pipe 21. The cotter 33 is made of a metal material such as a steel plate piece. The cotter 33 is joined to the inner surface 21d of the cover plate 21c by welding or the like.

In this embodiment, the cotters 33 are arranged at four locations on the inner surface 21d of the cover plate 21c at equal intervals in the circumferential direction, and in three vertical rows. The cotters 33 suppress the vertical displacement of the concrete portion 23. The number and arrangement of the cotters 33 can be set as appropriate.

In plan view, the line connecting the center O of the steel pipe 21 and the extension direction of the beam 1 is the first virtual line L1. In plan view, the line intersecting the center O of the steel pipe 21 at right angles and extending to the middle (center) of two adjacent first virtual lines L1 is the second virtual line L2. The cotter 33 is positioned on the second virtual line L2.

As shown in FIG. 1(b), the cotter 33 is provided at the upper end 21u (at a height position directly below the upper diaphragm 31), the lower end 21w (at a height position directly above the lower diaphragm 32), and the center in the vertical direction of the blocking plate 21c. The cotter 33 may be disposed below the upper end 21u of the blocking plate 21c with a gap therebetween, or above the lower end 21w of the blocking plate 21c with a gap therebetween.

The cotter 33 has a rectangular shape in a vertical cross section passing through the center O of the steel pipe 21 and the cotter 33. As shown in FIG. 1(a), the cotter 33 has a substantially rectangular shape in a horizontal cross section, with the surface that is joined to the inner surface 21d of the cover plate 21c having a shape (curved surface) corresponding to the inner surface 21d of the cover plate 21c. Because the horizontal cross section of the cotter 33 is substantially rectangular, it is possible to obtain a slip prevention reaction force for the concrete portion 23 more efficiently than, for example, a cotter with a circular cross section. It is preferable that the cotter 33 be slightly tapered to avoid stress concentration.

In the column-beam joint structure 100 configured in this manner, multiple cotters 33 are provided that protrude inward from the inner surface 21d of the steel pipe 21. The cotters 33 are fixed to the concrete portion 23, improving the adhesion between the steel pipe 21 and the concrete portion 23, thereby increasing the rigidity of the frame.

In addition, the beam 1 is joined to the first imaginary line L1 of the steel pipe 21, and the cotter 33 is provided on the second imaginary line L2 between the orthogonal first imaginary lines L1. This improves the fixation of the steel pipe 21 to the concrete portion 23 near the second imaginary line L2 (the portion not joined to the beam 1), and reinforces the rigidity in the column axis direction.

Second Embodiment
Next, a joint structure between a column and a beam according to a second embodiment will be described mainly with reference to Fig. 2 and Fig. 3. Note that components having the same functions as those in the above-mentioned embodiment will be denoted by the same reference numerals and will not be described.

FIG. 2 shows a joint structure between a column and a beam according to a second embodiment of the present invention, where (a) is a horizontal cross-sectional view and (b) is a cross-sectional view taken along line BB of (a).
As shown in FIG. 2, the column-beam joint structure 100A of this embodiment includes an upper diaphragm 31, a lower diaphragm 32, and a plurality of upper stiffening portions 34 and lower stiffening portions 35.

The upper stiffening part 34 is provided on the upper surfaces (upper parts) of the upper diaphragm 31 and the lower diaphragm 32. The lower stiffening part 35 is provided on the lower surfaces (lower parts) of the upper diaphragm 31 and the lower diaphragm 32. The upper stiffening part 34 and the lower stiffening part 35 are plate-like members having a predetermined thickness in the vertical direction. The upper stiffening part 34 and the lower stiffening part 35 are made of a metal material such as a steel plate.

The upper stiffening portion 34 and the lower stiffening portion 35 are provided at four locations spaced apart in the circumferential direction. In this embodiment, they are arranged on the first virtual line L1. The width of the upper stiffening portion 34 and the lower stiffening portion 35 is greater than the width of the upper flange 11 and the lower flange 12 of the beam 1.

Next, an analysis of the above-mentioned column-beam joint structure 100A will be described.
The effects of the upper stiffening portion 34 and the lower stiffening portion 35 were confirmed.
The upper flange 11 and the lower flange 12 have a width of 300 mm and a plate thickness of 28 mm. The upper diaphragm 31 and the lower diaphragm 32 have a plate thickness of 45 mm. Stiffening parts are provided on both the top and bottom of the upper diaphragm 31 and the lower diaphragm 32 or on either the top or bottom. In Example 1, the plate thickness of the stiffening parts is 3 mm (1.06 times), in Example 2, the plate thickness of the stiffening parts is 6 mm (1.13 times), in Example 3, the plate thickness of the stiffening parts is 9 mm (1.2 times), and in Example 4, the plate thickness of the stiffening parts is 45 mm (2 times). The steel pipe (covering plate) to which the diaphragm is attached is not taken into consideration. In addition, the plate thickness of the stiffening parts means the total thickness of the top and bottom when both the top and bottom are provided.

As shown in Figure 3, the thicker the stiffening part is, the higher the initial rigidity is, and the smaller the deformation at the yield strength level (2,750 kN) is.

In the column-beam joint structure 100A configured in this manner, the tensile rigidity in the beam tension direction is reinforced by the upper stiffening portion 34 and the lower stiffening portion 35 provided on the upper and lower parts of the upper diaphragm 31 and the lower diaphragm 32, respectively, thereby increasing the rigidity of the frame.

In addition, by arranging the upper stiffening portion 34 and the lower stiffening portion 35 on the first imaginary line L connecting the center O of the steel pipe 21 and the extension direction of the beam 1, damage to the upper diaphragm 31 and the lower diaphragm 32 near the yield line that is generally assumed (by guidelines, etc.) when designing the upper diaphragm 31 and the lower diaphragm 32 is suppressed.

The assembly procedures and the shapes and combinations of the components shown in the above-mentioned embodiments are merely examples, and may be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

In the embodiment shown above, the upper stiffening portion 34 is provided on the upper portion of the upper diaphragm 31 and the lower diaphragm 32, and the lower stiffening portion 35 is provided on the lower portion of the upper diaphragm 31 and the lower diaphragm 32, but the present invention is not limited to this. It is sufficient that the stiffening portion is provided on at least one of the upper portion and the lower portion of the upper diaphragm 31 and the lower diaphragm 32.

Reference Signs List 1 Beam 2 Column 11 Upper flange 12 Lower flange 21 Steel pipe 21a Outer surface 21d Inner surface 22 Main reinforcement 23 Concrete portion 31 Upper diaphragm 32 Lower diaphragm 33 Cotter 34 Upper stiffening portion (stiffening portion)
35 Lower stiffening part (stiffening part)
100 Column and beam joint structure L1 First virtual line L2 Second virtual line O Center

Claims (3)

A joint structure between a column of a concrete-filled steel pipe structure having a steel pipe extending vertically and formed into a cylindrical shape, a main bar disposed inside the steel pipe and extending vertically, and a concrete portion filled inside the steel pipe, and an H-shaped steel beam,
An upper diaphragm and a lower diaphragm are provided on the outer surface of the steel pipe, have a circular outer shape in a plan view, and are joined to the upper and lower flanges of the beam;
A plurality of cotters protruding inward from the inner surface of the steel pipe,
At least two of the beams are disposed perpendicular to the column;
In a plan view, a line connecting the center of the steel pipe and the extension direction of the beam is defined as a first virtual line,
In a plan view, a line extending from the center of the steel pipe to the middle of the two first virtual lines perpendicular to each other is defined as a second virtual line,
The cotter is disposed on the second imaginary line ,
The cotters are arranged at four locations at equal intervals in the circumferential direction and in three rows, one above the other.
A column-beam joint structure, characterized in that the cotters are provided at a height position directly below the upper diaphragm, a height position directly above the lower diaphragm, and an intermediate position between them. The joint structure for connecting a pillar and a beam according to claim 1 , wherein the cotter is formed in a generally rectangular shape when viewed from above. The joint structure between a column and a beam according to claim 2 , wherein the cotter is tapered in a plan view.

Images