JP2021191920A - Joint structure between column and beam - Google Patents

Abstract

To provide a joint structure between a column and a beam capable of improving workability of a joint part between the column and the beam and securing rigidity of the joint part between the column and the beam.SOLUTION: In the joint structure of a column 2 made of a concrete-filled steel pipe filled with concrete 23 inside a steel pipe 21 and a beam 3 made of a steel frame, a diaphragm member 4 provided in a joint part between the column 2 and the beam 3 and joined to the beam 3 is provided, the diaphragm member 4 has an annular diaphragm part 43 with a plan view shape that projects outward from the outer peripheral surface of a joint steel pipe 46 (steel pipe) and to which flanges 31 and 32 of the beam 3 are joined at an outer peripheral edge part 432, and a flange part 44 positioned inside the joint steel pipe 46 (steel pipe) and installed on an inner peripheral edge part 431 of the diaphragm part 43.SELECTED DRAWING: Figure 1

Description

The present invention relates to a joint structure of columns and beams.

Conventionally, in the RCST structure that combines columns of CFT structure (concrete-filled steel pipe structure) and beams of S structure (steel-framed beams), the beam penetration is a form of joining the columns so that the beams penetrate the columns. A type and an outer diaphragm type in which a beam is joined to a diaphragm joined to the outside of a column are assumed (see, for example, Patent Documents 1 and 2).
In the beam penetration type, the flange of the portion of the beam that penetrates the column can be utilized when installing a guide for managing the required anchoring length of the column joint rebar.
In the outer diaphragm format, a circular diaphragm having a circular plan view or a rectangular diaphragm having a rectangular view is adopted. The circular diaphragm fits better with the outer wall than the rectangular diaphragm, and can realize a lean frame plan. Further, the circular diaphragm can simplify the detail of the joint portion between the column and the beam when the beam is an oblique beam.

Japanese Unexamined Patent Publication No. 2020-2628 Japanese Unexamined Patent Publication No. 2006-2351

In the outer diaphragm type, when installing a guide for managing the required fixing length of the joint reinforcing bar of the column, the flange of the beam cannot be used as in the beam penetration type, and the workability is poor. There is.
Further, as compared with the rectangular diaphragm, the circular diaphragm is more likely to be deformed in the inward direction and the outward direction of the plate surface when resisting the tensile force from the beam, and it is necessary to secure the rigidity.

The present invention has been made in view of the above-mentioned problems, and it is possible to improve the workability of the joint portion between the column and the beam and to secure the rigidity of the joint portion between the column and the beam. It is intended to provide a joint structure between a beam and a beam.

In order to achieve the above object, the joint structure of a pillar and a beam according to the present invention is a joint structure of a concrete-filled steel pipe pillar and a steel-framed beam in which concrete is filled inside the steel pipe. It has a diaphragm member provided at a joint portion with and to which the beam is joined, and the diaphragm member projects outward from the outer peripheral surface of the steel pipe, and the flange of the beam is joined to the outer peripheral edge portion in a plan view. It is characterized by having a diaphragm portion having an annular shape and a flange portion located inside the steel pipe and erected on an inner peripheral edge portion of the diaphragm portion.

In the present invention, in the diaphragm member, a flange portion is erected inside an annular diaphragm portion to which a beam projects outward from the outer peripheral surface of the steel pipe and is joined. Therefore, the flange portion can prevent the diaphragm portion from being deformed in the plate surface inward direction and the plate surface outward direction when resisting the tensile force from the beam. As a result, the rigidity of the joint portion between the column and the beam can be ensured regardless of the shape of the diaphragm portion (circular shape, rectangular shape, etc.).
In addition, at the time of construction, when installing a guide for managing the required fixing length of the joint reinforcing bar of the column, the flange portion located inside the steel pipe can be used, so that the joint between the column and the beam can be used. Workability can be improved.

Further, in the joint structure of the column and the beam according to the present invention, the flange portion may have a cross shape in a plan view.
With such a configuration, the rigidity of the diaphragm member can be improved, and the rigidity of the joint portion between the column and the beam can be ensured. Further, since the place where the guide for managing the required fixing length of the joint reinforcing bar of the column can be installed is in a cross shape inside the steel pipe, the guide can be installed according to the position of the reinforcing bar.

Further, in the joint structure between the column and the beam according to the present invention, the beam is joined to the diaphragm portion from all sides, and the flange portion is joined to the beam at the outer peripheral edge portion of the diaphragm portion 4 It may be connected to the inner peripheral edge portion of the diaphragm portion at four positions facing each other.
With such a configuration, the rigidity of the diaphragm member can be efficiently improved, and the rigidity of the joint portion between the column and the beam can be ensured.

According to the present invention, the workability of the joint portion between the column and the beam can be improved, and the rigidity of the joint portion between the column and the beam can be ensured.

It is a horizontal cross-sectional view which shows the joint structure of a column and a beam by embodiment of this invention, and is the cross-sectional view taken along line AA of FIG. It is a vertical cross-sectional view which shows the joint structure of a column and a beam by embodiment of this invention, and is the BB line sectional view of FIG. It is a perspective view of the diaphragm member to which the flange of a beam is joined. It is a figure which shows the analysis model using the conventional annular diaphragm part. It is a figure which shows the analysis model using the diaphragm member of this embodiment. It is a figure which shows the other analysis model using the diaphragm member of this embodiment. It is a graph which shows the analysis result (relationship between deformation and load).

Hereinafter, the joint structure between the column and the beam according to the embodiment of the present invention will be described with reference to FIGS. 1 to 7.
As shown in FIGS. 1 and 2, the joint structure 1 of the column and the beam according to the present embodiment is a joint portion between the column 2 of the concrete-filled steel pipe structure (CFT structure) and the beam 3 of the steel frame structure (S structure). It is the structure of the column-beam joint portion 11).
The column 2 has a steel pipe 21 extending in the vertical direction, a reinforcing bar 22 extending in the vertical direction inside the steel pipe 21, and a concrete 23 filled in the steel pipe 21. In FIGS. 1 and 2, the hatching of the concrete 23 is omitted.
The beam 3 is a steel beam made of H-shaped steel and has a lower flange 31, an upper flange 32, and a web 33.
In the present embodiment, a column-beam joining member 45 is provided between the column 2 on the upper floor and the column 2 on the lower floor, and the four beams 3 are joined to the column-beam joining member 45 from all sides. Assuming that the horizontal directions orthogonal to each other are the X direction and the Y direction, the two beams 3 extend in the X direction and the other two beams 3 extend in the Y direction.

The beam-column joint member 45 has a joint steel pipe 46, an upper diaphragm member 41, and a lower diaphragm member 42. Hereinafter, the upper diaphragm member 41 and the lower diaphragm member 42 may be referred to as a diaphragm member 4.
The joint steel pipe 46 is formed of a steel pipe having the same diameter as the steel pipe 21 of the column 2. The joint steel pipe 46 is coaxially arranged in a direction in which the axis extends in the vertical direction. The joint steel pipe 46 extends substantially over the vertical direction of the beam-column joint 11.

As shown in FIGS. 3 and 3, the diaphragm member 4 is a member obtained by processing a steel plate and is formed in a flat plate shape. The diaphragm member 4 is arranged so that the plate surface is a horizontal plane. The diaphragm member 4 has a diaphragm portion 43 and a flange portion 44. In the present embodiment, the diaphragm portion 43 and the flange portion 44 are integrally formed by processing one steel plate.
The diaphragm portion 43 is formed in an annular shape having a substantially circular outer shape. The diaphragm portion 43 is provided so as to project from the entire outer circumference of the joint portion steel pipe 46.
In the diaphragm portion 43 of the lower diaphragm member 42, the inner peripheral edge portion 431 is joined to the lower end portion of the joint portion steel pipe 46. In the diaphragm portion 43 of the upper diaphragm member 41, the inner peripheral edge portion 431 is joined to the upper end portion of the joint portion steel pipe 46.

The flange portion 44 is provided inside the diaphragm portion 43, and is arranged inside the joint portion steel pipe 46 in a plan view seen from the vertical direction. The flange portion 44 is formed in a cross shape in which a long flat plate portion 441 whose plan view shape extends in the X direction and a long flat plate portion 442 extending in the Y direction are orthogonal to each other. In the flange portion 44, both end portions 441a of the long flat plate portion 441 extending in the X direction and both end portions 442a of the long flat plate portion 442 extending in the Y direction are connected to the inner peripheral edge portion 431 of the diaphragm portion 43. That is, the flange portion 44 is erected inside the diaphragm portion 43. The upper surface 443 of the flange portion 44 and the upper surface 433 of the diaphragm portion 43 are provided so as to be flush with each other. The lower surface 444 of the flange portion 44 and the lower surface 434 of the diaphragm portion 43 are provided so as to be flush with each other.
In the present embodiment, the width dimension Bdf of the flange portion 44 (width dimension Bdf of the flat plate portions 441 and 442) is set to 1/6 or more and 1/3 or less of the width dimension Bf of the lower flange 31 and the upper flange 32 of the beam 3. Has been done.

As described above, the column-beam joining member 45 is provided between the column 2 on the upper floor and the column 2 on the lower floor. The beam-column joint member 45 is placed on the steel pipe 211 of the column 2 on the lower floor, and the steel pipe 212 of the column 2 on the upper floor is placed on the steel pipe 211.
The upper diaphragm member 41 is arranged at a height at which the upper flange 32 of the beam 3 is provided. The lower diaphragm member 42 is arranged at a height at which the lower flange 31 of the beam 3 is provided. The upper flange 32 is joined to the outer peripheral edge portion 432 of the diaphragm portion 43 of the upper diaphragm member 41. The lower flange 31 is joined to the outer peripheral edge portion 432 of the diaphragm portion 43 of the lower diaphragm member 42.
Inside the joint steel pipe 46, reinforcing bars 22 of columns 2 on the upper and lower floors are continuously provided, and concrete 23 is filled.
The reinforcing bar 22 of the column 2 is inserted into a region inside the diaphragm portion 43 of the diaphragm member 4 so as not to interfere with the flange portion 44.

Next, the action / effect of the joint structure 1 between the column and the beam according to the present embodiment will be described.
In the joint structure 1 of the column and the beam according to the present embodiment, the diaphragm member 4 has a flange portion 44 erected inside the annular diaphragm portion 43 to which the beam 3 is joined so as to project outward from the outer peripheral surface of the steel pipe 21. Has been done. Therefore, the flange portion 44 can prevent the diaphragm portion 43 from being deformed in the plate surface inward direction and the plate surface outward direction when resisting the tensile force from the beam 3. Thereby, the rigidity of the column-beam joint portion 11 can be ensured regardless of the shape (circular shape, rectangular shape, etc.) of the diaphragm portion 43.
Further, at the time of construction, when installing a guide for managing the required fixing length of the reinforcing bar 22 (joint reinforcing bar 221) located in the joint steel pipe 46 of the column 2, the flange located inside the joint steel pipe 46 is installed. Since the portion 44 can be used, the workability of the column-beam joint portion 11 can be improved.

Further, in the joint structure 1 of the column and the beam according to the present embodiment, the flange portion 44 has a cross shape in a plan view.
With such a configuration, the rigidity of the diaphragm member 4 can be improved, and the rigidity of the column-beam joint portion 11 can be ensured. Further, since the place where the guide for managing the required fixing length of the joint reinforcing bar 221 of the column 2 can be installed is in a cross shape inside the joint steel pipe 46, the guide is installed according to the position of the reinforcing bar 22. be able to.

Further, in the joining structure 1 of the column and the beam according to the present embodiment, the beam 3 is joined to the diaphragm portion 43 from all sides, and the beam 3 at the outer peripheral edge portion 432 of the diaphragm portion 43 is joined to the flange portion 44. It is connected to the inner peripheral edge portion 431 of the diaphragm portion 43 at four positions facing each other at the four positions.
With such a configuration, the rigidity of the diaphragm member 4 can be efficiently improved, and the rigidity of the column-beam joint portion 11 can be ensured.

Next, the analysis regarding the rigidity of the diaphragm member of the joint structure between the column and the beam according to the present embodiment will be described.
At the joint between the column and the beam to be analyzed, the width dimension Bf (see FIG. 3) of the flanges 31 and 32 of the beam 3 was set to 300 mm, the plate thickness was set to 28 mm, and the plate thickness of the diaphragm member 4 was set to 45 mm. A 1/4 model was used in consideration of symmetry. FIG. 4 shows an analysis model having a conventional diaphragm 104 (without a flange portion), and FIG. 5 shows a width dimension Bdf of the flange portion 44 (see FIG. 3) which is 1/3 of the width dimension Bf of the flanges 31 and 32 of the beam 3. An analysis model of (Bdf / Bf = 1/3) is shown, and FIG. 6 shows that the width dimension Bdf of the flange portion 44 is 1/6 (Bdf / Bf = 1/6) of the width dimension Bf of the flanges 31 and 32 of the beam 3. ) Is shown.
The analysis was performed by MD. Nastran (SOL106) was used. The non-linear characteristics of each element were ^{analyzed with the F value (325 N / mm 2} ) of the steel material as the yield point, and the rigidity was analyzed as complete elasto-plasticity using the Young's modulus of the steel material. The contact and separation between the diaphragm member and concrete are expressed using GAP elements.

From the analysis results shown in FIG. 7, it can be confirmed that the rigidity is remarkably increased when the cross-shaped flange portion 44 is present. It can be seen that when the ratio Bdf / Bf of the width dimension Bdf of the flange portion 44 of the diaphragm member 4 to the width dimension Bf of the flanges 31 and 32 of the beam 3 is 1/6 or more and 1/3 or less, an increase in rigidity can be expected.

Although the embodiment of the joint structure 1 of the column and the beam according to the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately changed without departing from the spirit of the present invention.
For example, in the above embodiment, the shape of the flange portion 44 in a plan view is a cross shape, but it may be a shape other than the cross shape.
Further, in the above embodiment, the diaphragm portion 43 is formed in an annular shape having a substantially circular outer shape, but may be formed in an annular shape having a rectangular or polygonal outer shape.

Further, in the above embodiment, the beam 3 is joined to the diaphragm portion 43 from all sides, and the flange portion 44 faces each of the four positions of the outer peripheral edge portion 432 of the diaphragm portion 43 to which the beam 3 is joined. It is connected to the inner peripheral edge portion 431 of the diaphragm portion 43 at one position. On the other hand, the position where the beam 3 is joined and the position where the flange portion 44 is connected to the diaphragm portion 43 may be appropriately set.

Further, in the above embodiment, the diaphragm member 4 is joined to the axial end portion of the steel pipe 21. On the other hand, in the diaphragm member 4, the diaphragm portion 43 may be joined to the outer peripheral surface of the steel pipe 21, and the flange portion 44 may be joined to the inner peripheral surface of the steel pipe 21.
Further, in the embodiment, the width dimension Bdf of the flange portion 44 is set to 1/6 or more and 1/3 or less of the width dimension Bf of the lower flange 31 and the upper flange 32 of the beam 3. On the other hand, the ratio of the width dimension Bdf of the flange portion 44 to the width dimension Bf of the lower flange 31 and the upper flange 32 of the beam 3 may be other than the above.

1 Joint structure 2 Column 3 Beam 4 Diaphragm member 11 Column-beam joint 21 Steel pipe 23 Concrete 31 Lower flange (flange)
32 Upper flange (flange)
43 Diaphragm part 44 Flange part 45 Column-beam joint member 46 Joined steel pipe (steel pipe)
431 Inner peripheral edge 432 Outer peripheral edge

Claims (3)

In the joint structure of concrete-filled steel pipe columns filled with concrete inside steel pipes and steel beams.
It has a diaphragm member provided at a joint portion between the column and the beam and to which the beam is joined.
The diaphragm member is
A diaphragm portion having an annular shape in a plan view, which protrudes outward from the outer peripheral surface of the steel pipe and the flange of the beam is joined to the outer peripheral edge portion.
A column-beam joint structure characterized by having a flange portion located inside the steel pipe and erected on an inner peripheral edge portion of the diaphragm portion. The joint structure between a column and a beam according to claim 1, wherein the flange portion has a cross shape in a plan view. The beam is joined to the diaphragm portion from all sides.
The claim is characterized in that the flange portion is connected to the inner peripheral edge portion of the diaphragm portion at four positions facing each other at four positions of the outer peripheral edge portion of the diaphragm portion to which the beam is joined. The joint structure between the column and the beam according to 2.

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