JP7666972B2 - 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 (RCST structure) between a column of a concrete-filled steel pipe structure (CFT structure), in which reinforcing bars and concrete are filled inside the steel pipe, and a beam of a steel frame structure (S structure) has been known for some time (see Patent Document 1 below).

An external diaphragm type is also known in which an external diaphragm is welded to the outer periphery of the column and then welded to the flange of the beam, thereby increasing the rigidity of the joint.

During construction, the concrete for the floor is poured after pouring the concrete inside the steel pipes of the columns on the lower floor. If the strength of the concrete used for the columns and beams is different, care must be taken to prevent the concrete in the columns from mixing with the concrete for the floor. For this reason, after pouring concrete inside the steel pipes of the columns on the lower floor, the joining rebars are surrounded by a cylindrical member at floor height (box punching) before pouring the concrete for the floor. In this way, the concrete for the floor is prevented from getting inside the columns. Next, the steel pipes of the columns on the upper floor are installed and concrete is poured inside the steel pipes, after which additional concrete for the floor is poured around the columns at floor height to repair the floor.

JP 2010-261270 A

However, with the above construction method, the concrete for the floor height portion of the pillars is poured after the concrete for the pillars on the upper floors has been poured. As a result, if it rains before the concrete for the floor height portion of the pillars is poured, the rain will flow around the pillars, which are surrounded by cylindrical members, and into the floor below, which will lead to an extension of the construction period for interior work on the lower floors, and there is a problem that the construction period will be prolonged.

Therefore, the present invention was made in consideration of the above circumstances, and provides a joint structure between a column and a beam that is easy to construct and can ensure rigidity and strength.

In order to achieve the above object, the present invention employs the following means.
In other words, the column-to-beam joint structure of the present invention is a joint structure between a column of concrete-filled steel pipe construction in which concrete is filled inside the steel pipe and a beam of steel frame construction, and comprises an upper diaphragm member that is arranged at the joint between the column and the beam, provided at the lower part of the steel pipe of the column , protruding outward from the steel pipe, and having an upper flange of the beam joined to its outer periphery, and an outer steel pipe that protrudes upward from the upper diaphragm member and forms a ring in a planar view, and the outer diameter of the outer steel pipe is larger than the outer diameter of the steel pipe of the column.

In the joint structure between the column and the beam configured in this way, the outer steel pipe, which is annular in plan view, protrudes upward from the upper diaphragm member, and the outer diameter of the outer steel pipe is larger than the outer diameter of the steel pipe of the column. With this configuration, the outer steel pipe replaces the conventional box-punched tubular member, and the possibility of the concrete for the column of the lower floor being mixed with the concrete for the floor slab is reduced. Therefore, the concrete for the floor slab can be poured without the box-punching to install the tubular member around the column, which makes the construction easy.
In addition, by providing an outer steel pipe on the outside of the steel pipe of the column, the rigidity and strength of the joint between the column and the beam can be increased.

In addition, in the column-beam joint structure of the present invention, the outer diameter of the outer steel pipe may be smaller than the outer diameter of the upper diaphragm member.

In a column-beam joint structure configured in this way, the outer diameter of the outer steel pipe is smaller than the outer diameter of the upper diaphragm member. Therefore, the outer steel pipe can be attached to the upper surface of the upper diaphragm member.

In addition, in the column-beam joint structure according to the present invention, the outer steel pipe may be annular in plan view.

In a column-beam joint structure constructed in this way, the outer steel pipe is annular in plan view. This allows the rigidity and strength to be increased evenly around the circumference of the joint.

The column-beam joint structure of the present invention is easy to construct and ensures rigidity and strength.

1A and 1B are a horizontal cross-sectional view and a vertical cross-sectional view, respectively, showing a joint structure between a column and a beam according to one embodiment of the present invention. 1 is a perspective view showing a schematic view of a main part of a joint structure between a pillar and a beam according to one embodiment of the present invention; FIG. 1 shows an analytical model, (a) shows Comparative Example 1, (b) shows Comparative Example 2, (c) shows Comparative Example 3, and (d) shows an embodiment. 13 is a graph showing the analysis results.

A joint structure between a pillar and a beam according to one 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 one embodiment of the present invention, in which (a) is a horizontal cross-sectional view and (b) is a vertical cross-sectional view.
As shown in Fig. 1, the column-beam joint structure 100 of this embodiment is a structure of a joint portion a between a concrete-filled steel pipe (CFT) column 2 and a steel frame (S) beam 1. In this embodiment, four beams 1 are arranged perpendicularly in a plan view to two upper and lower columns 2. 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 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 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 the vertical direction as its axial direction.

The main reinforcement 22 is arranged along the inside of the steel pipe 21. The main reinforcement 22 is arranged at intervals in the circumferential direction. The main reinforcement 22 extends vertically. The concrete portion 23 is filled inside the steel pipe 21. The main reinforcement 22 is fixed to the concrete portion 23. The main reinforcement 22 and the concrete portion 23 are arranged over approximately the entire length of the lower floor column 2, the column-beam joint member 3 described below, and the upper floor column 2.

A column-beam joint member 3 is provided between the upper floor column 2 and the lower floor column 2. Four beams 1 are joined to the column-beam joint members 3 on all four sides.

The column-beam joint member 3 has a cover plate 31, an upper diaphragm member 32, a lower diaphragm member 33, and an outer steel pipe 34. Hereinafter, the upper diaphragm member 32 and the lower diaphragm member 33 may be referred to as diaphragm members 30.

The cover plate 31 is formed in a cylindrical shape with the vertical direction as its axial direction. The diameter of the cover plate 31 is approximately the same as the diameter of the steel pipe 21 of the column 2. The cover plate 31 is arranged coaxially with the steel pipe 21 of the column 2. The cover plate 31 extends over the entire vertical length of the joint a. The height of the cover plate 31 is lower than the height of the beam 1 by the height of the upper diaphragm member 32 and the lower diaphragm member 33.

The diaphragm member 30 has the function of transmitting load from the beam 1 to the column 2. The diaphragm member 30 is provided so as to protrude radially outward (outward) from the steel pipe 21. The diaphragm member 30 is annular in plan view. The outer and inner shapes of the diaphragm member 30 are circular. The diaphragm member 30 is arranged coaxially with the covering plate 31. The diaphragm member 30 is flat. The plate surface of the diaphragm member 30 is along a horizontal plane. The diaphragm member 30 is formed, for example, by processing a steel plate.

The inner peripheral edge 32a of the upper diaphragm member 32 is joined to the upper end of the cover plate 31 and the lower end of the steel pipe 21 of the column 2 on the upper floor. The upper diaphragm member 32 is positioned at approximately the same height as the upper flange 11 of the beam 1. The outer peripheral edge 32b of the upper diaphragm member 32 is joined to the upper flange 11.

The inner peripheral edge 33a of the lower diaphragm member 33 is joined to the lower end of the cover plate 31 and the upper end of the steel pipe 21 of the column 2 of the lower floor. The lower diaphragm member 33 is positioned at approximately the same height as the lower flange 12 of the beam 1. The outer peripheral edge 33b of the lower diaphragm member 33 is joined to the lower flange 12.

The outer steel pipe 34 protrudes upward from the upper surface 32u of the upper diaphragm member 32. As shown in FIG. 2 (in FIG. 2, only the upper flange 11 of the beam 1 configuration is shown), the outer steel pipe 34 is annular in plan view. The height of the outer steel pipe 34 is, for example, approximately 120 mm to 200 mm.

The outer steel pipe 34 is arranged coaxially with the cover plate 31 and the steel pipe 21 of the column 2. The outer steel pipe 34 is arranged outside the steel pipe 21 with a gap between them. The outer diameter of the outer steel pipe 34 is larger than the outer shape of the cover plate 31 and the outer diameter of the steel pipe 21 of the column 2. The outer diameter of the outer steel pipe 34 is smaller than the outer shape of the upper diaphragm member 32.

The outer steel pipe 34 is formed, for example, by processing a steel plate. The outer steel pipe 34 is joined to the upper surface 32u of the upper diaphragm member 32 by welding or the like.

As shown in FIG. 1(b), a concrete section 35 filled with concrete is provided in the space outside the steel pipe 21 of the upper floor column 2 and inside the outer steel pipe 34. Note that the concrete section 35 does not necessarily have to be provided.

A floor slab 41 is formed on the upper side of the beam 1. The floor slab 41 contains concrete and is formed in a flat plate shape. The plate surface of the floor slab 41 is along the horizontal plane. The floor slab 41 is formed on the outside of the outer steel pipe 34 of the column-beam connection member 3. The height of the floor slab 41 is lower than the height of the outer steel pipe 34.

Next, a method for constructing the above-mentioned column-to-beam joint structure 100 will be described.
First, the column-beam joint member 3 is installed on the upper side of the steel pipe 21 of the column 2 of the lower floor. The main reinforcement 22 of the column 2 is inserted into the column-beam joint member 3.

Next, concrete is poured inside the steel pipes 21 of the columns 2 on the lower floor and inside the cover plates 31 of the column-beam connection members 3.

Next, the upper flange 11 of the beam 1 is joined to the upper diaphragm member 32 of the column-beam connection member 3, the lower flange 12 of the beam 1 is joined to the lower diaphragm member 33, and the web 13 of the beam 1 is joined to the cover plate 31, thereby joining the column-beam connection member 3 and the beam 1.

Next, the concrete for the floor slab is poured.
Conventionally, in order to prevent the concrete of the floor slab from mixing with the concrete of the column 2, a box cut is performed to surround the main reinforcement 22 of the column 2 of the upper floor with a cylindrical member, and the concrete of the floor slab is poured outside the cylindrical member. In this embodiment, the height of the outer steel pipe 34 of the column-beam joint member 3 is higher than the height of the floor slab 41 to be constructed. Therefore, the outer steel pipe 34 serves as a substitute for the cylindrical member for the box cut, and the floor slab 41 is constructed by pouring concrete outside the outer steel pipe 34.

Next, the steel pipe 21 of the column 2 on the upper floor is installed on the upper side of the column-beam joint member 3. Main reinforcement 22 is placed inside the steel pipe 21. The column-beam joint member 3 is also installed on the upper side of the steel pipe 21 of the column 2 on the upper floor, and construction is carried out in the same manner as above, and concrete is poured inside the steel pipe 21 of the upper column 2.

Next, an analysis of the above-mentioned column-beam joint structure 100 will be described.
The analysis model is shown in Figure 3. The joint to be examined had a beam flange (upper flange 11) with a width of 300 mm and a plate thickness (vertical thickness) of 28 mm. The plate thickness (vertical thickness) of the circular outer diaphragm (upper diaphragm member 32) was 45 mm. The thickness tc of the cover plate (cover plate 31) and the outer steel pipe (outer steel pipe 34) was 6 mm. The circular outer diaphragm, beam flange, cover plate, and outer steel pipe were modeled using shell elements. Considering symmetry, a 1/4 model was used, and MD. Nastran (SOL106) was used for the analysis. The nonlinear characteristics of each element were analyzed as perfect elastic-plasticity using the F value (325 N/mm ² ) of the steel material as the yield point, and the stiffness was calculated using the Young's modulus of the steel material. The contact and separation between the circular outer diaphragm and the concrete were expressed using GAP elements.

Comparative example 1 shown in Figure 3(a) is a conventional circular outer diaphragm type. Comparative example 2 shown in Figure 3(b) shows a case where a cover plate (φ=900) is welded to a circular outer diaphragm. Comparative example 3 shown in Figure 3(c) shows a case where a cover plate (φ=900) and a steel pipe of the same shape as the cover plate, φ'=900 mm (φ'/φ=1.0), are welded to a circular outer diaphragm. The example shown in Figure 3(d) shows a case where a cover plate (φ=900) and an outer steel pipe, φ'=1080 mm (φ'/φ=1.2), are welded to a circular outer diaphragm.

From the analysis results shown in Figure 4, it can be seen that the rigidity is increased when there is a cover plate, a steel pipe with φ' = 900 mm, and an outer steel pipe (Example, Comparative Examples 2 and 3). When comparing the case where there is only a cover plate (Comparative Example 2) with the case where there is a steel pipe with φ' = 900 mm (Comparative Example 3) and the case where there is an outer steel pipe (Example), it can be seen that in Comparative Example 3, the rigidity is increased due to the influence of the steel pipe with φ' = 900 mm, and in the Example, the rigidity is increased due to the influence of the outer steel pipe. It can also be seen that there is a stiffening effect when φ'/φ is in the range of 1.0 to 1.2.

In the column-beam joint structure 100 configured in this manner, the outer steel pipe 34, which is annular in plan view, protrudes upward from the upper diaphragm member 32, and the outer diameter of the outer steel pipe 34 is larger than the outer diameter of the steel pipe 21 of the column 2. With this configuration, the outer steel pipe 34 takes the place of a conventional box-punched tubular member, reducing the possibility of the concrete for the column 2 on the lower floor and the concrete for the floor slab 41 mixing. Therefore, the concrete for the floor slab 41 can be poured without the need to punch out a box to install a tubular member around the column 2, which improves workability.

In addition, by providing an outer steel pipe 34 on the outside of the steel pipe 21 of the column 2, the rigidity and strength of the joint a can be increased.

The outer diameter of the outer steel pipe 34 is smaller than the outer diameter of the upper diaphragm member 32. Therefore, the outer steel pipe 34 can be provided on the upper surface 32u of the upper diaphragm member 32.

The outer steel pipe 34 is annular in plan view. This allows the rigidity and strength to be increased evenly around the periphery of the joint a.

In addition, if the outer steel pipe is to have the same diameter as the steel pipe 21 of the column 2, the steel pipe 21 must be joined to the upper side of the outer steel pipe with a metal-to-metal joint, which can lead to misalignment and makes precision control difficult. In this embodiment, the outer steel pipe 34, which is larger in outer diameter than the steel pipe 21 of the column 2, is attached to the joint a, which can eliminate the effect of misalignment between the steel pipe 21 and the outer steel pipe 34, allowing for precise construction.

In addition, the outer steel pipe 34 is not connected to the steel pipe 21 of the column 2 and is independent of the steel pipe 21, so the outer steel pipe 34 is not affected by the deformation of the steel pipe 21, allowing for precise construction.

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.

For example, in the embodiment shown above, the outer steel pipe 34 is formed in a circular ring shape when viewed from above, but the present invention is not limited to this. The outer steel pipe may be formed in a rectangular ring shape when viewed from above.

1 Beam 2 Column 21 Steel pipe 34 Outer steel pipe 100 Joint structure a Joint part

Claims (3)

A joint structure between a column of a concrete-filled steel pipe structure, in which concrete is filled inside the steel pipe, and a beam of a steel frame structure,
An upper diaphragm member is disposed at a joint between the column and the beam, provided at a lower part of the steel pipe of the column , protruding outward from the steel pipe, and having an outer peripheral edge to which an upper flange of the beam is joined;
an outer steel pipe projecting upward from the upper diaphragm member and having an annular shape in a plan view;
A column-beam joint structure, in which the outer diameter of the outer steel pipe is larger than the outer diameter of the steel pipe of the column. The column-beam joint structure according to claim 1, in which the outer diameter of the outer steel pipe is smaller than the outer diameter of the upper diaphragm member. The column-beam joint structure according to claim 1 or 2, in which the outer steel pipe is annular in plan view.

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