JP2023072889A - Steel pipe column structure - Google Patents

Abstract

To provide a technique that can appropriately prevent plastic buckling due to a deformation concentration phenomenon while adopting a reasonable configuration excellent in cost, workability or the like in a steel pipe column structure comprising a steel pipe-made outside column and an inside column inserted into the outside column.SOLUTION: A steel pipe column structure 20 comprises a steel pipe-made outside column 21 and an inside column 22 inserted into the outside column 21. In the outside column 21, both of an upper end 21a and a lower end 21b are fixed to a building skeleton. In the inside column 22, out of an upper end 22a and a lower end 22b, one is fixed to the building skeleton as a fixed portion, and the other is not fixed to the building skeleton as a non-fixed portion and is separated from the outside column 21 by interposing a clearance 30.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a steel pipe column structure including an outer column made of steel pipe and an inner column inserted inside the outer column.

Patent Literature 1 describes a steel pipe column structure in which an inner column that bears the vertical load of the building is surrounded by an outer column that bears the horizontal load of the building. In the steel pipe column structure described in Patent Document 1, when the inner column bends under a vertical load, the outer surface of the inner column comes into contact with the inner surface of the outer column, so that the deflection is restrained to a certain extent or more. , plastic buckling due to vertical load is prevented. Furthermore, the outer pillars have sufficient horizontal stiffness to prevent plastic buckling due to horizontal loads.

Japanese Patent No. 5008610

In the steel pipe column structure described in Patent Document 1, the vertical load of the building is borne by the inner pillars, and the horizontal load of the building is borne by the outer pillars. becomes. In addition, the outer pillars that surround the inner pillars need to restrain the deflection of the inner pillars above a certain level while bearing the horizontal load. This may lead to higher cost and larger size.

In addition, in recent years, studies have been made on the phenomenon of deformation concentration in the lower layers of high-rise buildings. The phenomenon of concentration of deformation in the lower part of a high-rise building is that when the columns that bear the vertical load of a high-rise building become long over several stories in the lower part, all the columns come together as the shaking (sway) progresses due to the horizontal load during a large earthquake. This is a plastic buckling phenomenon in which a deformation mode that bends in an arcuate shape occurs. In addition, the steel pipe column structure described in Patent Document 1 cannot sufficiently prevent plastic buckling due to deformation concentration phenomenon, particularly in the lower layers, of the outer columns that bear the horizontal load during a large earthquake.

In view of this situation, the main object of the present invention is to provide a steel pipe column structure having a steel pipe outer column and an inner column inserted inside the outer column, which is rational and superior in terms of cost and workability. The purpose of the present invention is to provide a technology capable of suitably preventing plastic buckling due to a deformation concentration phenomenon while adopting a conventional structure.

A first characteristic configuration of the present invention is a steel pipe column structure comprising a steel pipe outer column and an inner column inserted inside the outer column,
Both the upper end and the lower end of the outer pillar are fixed to the building frame,
In the inner pillar, one of the upper end portion and the lower end portion is fixed to the building frame as a fixed portion, and the other is not fixed to the building frame as a non-fixed portion, and a gap is interposed with respect to the outer pillar. Let it be spaced apart.

According to this configuration, only the upper end portion or the lower end portion of the inner pillar is fixed to the building frame as the fixed portion, and the other portion is not fixed to the building frame as the non-fixed portion and is attached to the outer pillar. It is spaced apart with a gap between them. Therefore, during normal times other than during a major earthquake, neither the vertical load nor the horizontal load of the building is transmitted to the inner pillars, but is borne by the outer pillars fixed to the foundation and upper floors of the building. . As for the inner pillar, it can be installed easily and inexpensively by simply inserting it into the outer pillar and fixing only one of the upper end and the lower end to the building frame. Influence on structural design can be avoided because it does not bear horizontal load. Furthermore, the outer pillars can be installed easily and inexpensively as general steel pipe pillars that bear both vertical and horizontal loads.
On the other hand, during a major earthquake, when the outer pillar, which bears the vertical load, bends in an arc as the shaking progresses due to the horizontal load, the non-fixed part of the inner pillar contacts the inner surface of the outer pillar, causing the outer pillar to flex. It is possible to suitably prevent plastic buckling due to the deformation concentration phenomenon of the outer column by restraining the deflection above a certain level. Furthermore, since the inner column does not bear the vertical load, it exhibits a large bending rigidity and can appropriately restrain the bending of the outer column.
Therefore, according to the present invention, in a steel pipe column structure having a steel pipe outer column and an inner column inserted inside the outer column, a rational configuration excellent in terms of cost, workability, etc. is adopted. However, it is possible to provide a technology capable of suitably preventing plastic buckling due to deformation concentration phenomenon.

A second characteristic configuration of the present invention is that, in the unfixable portion of the inner column, the inner column is inserted through an opening formed in the inner diaphragm of the outer column, and the edge of the opening and the inner column The gap is formed between the outer surface of the

According to this configuration, when the outer column bends in an arc shape, the outer surface of the non-fixable portion of the inner column comes into contact with the edge of the opening formed in the inner diaphragm of the outer column, thereby suppressing the deformation of the outer column. It is possible to reliably constrain the bending of the outer column above a certain level while suppressing it.

The third characteristic configuration of the present invention is that the inner pillar is provided from the lower end portion fixed to the base portion as the fixing portion to the upper end portion extending to the upper floor side as the non-fixing portion. be.

According to this configuration, when the outer pillar that bears the vertical load bends in a bow shape as the shaking progresses due to the horizontal load during a major earthquake, the lower end of the inner pillar that is fixed to the foundation part is on the upper floor side. Since the non-fixed portion abuts against the inner surface of the outer pillar, the lower layer of the outer pillar is restrained from bending to a certain extent or more, so that plastic buckling due to the deformation concentration phenomenon in the lower layer of the outer pillar can be preferably prevented. can.

A diagram showing a schematic configuration of the steel pipe column structure of the present embodiment and a normal state A diagram showing the schematic configuration of the steel pipe column structure of this embodiment and the state at the time of a large earthquake. Explanatory drawing of deformation concentration phenomena in the lower part of a high-rise building during a large earthquake

An embodiment of the present invention will be described based on the drawings.
Referring to FIG. 3, the steel pipe column structure 20 of the present embodiment prevents plastic buckling due to deformation concentration phenomenon that occurs particularly in the lower part of a high-rise building 1 having steel pipe columns 2 and steel beams 3, for example. It is adopted as a structure for suitable prevention. In other words, the deformation concentration phenomenon occurs when the columns 2 that bear the vertical load of the high-rise building 1 are elongated over several lower layers, and as the shaking (sway) progresses due to the horizontal load F during a large earthquake, 3, this is a plastic buckling phenomenon in which a deformation mode in which all the columns 2 flex in an arcuate shape is generated.
A detailed configuration of the steel pipe column structure 20 will be described below.

As shown in FIGS. 1 and 2, the steel pipe column structure 20 is a steel frame (for example, H-beam) foundation beam 3B (for example, H-shaped steel) provided on the first floor in the lower part of the building 1 (see FIG. 3). An example of the base portion) and an upper floor beam 3A made of a steel frame (for example, H-beam steel) provided on the floor portion of the second floor, which is the upper floor side. The steel pipe column structure 20 has a double pipe structure including a steel pipe outer column 21 and a steel pipe inner column 22 inserted inside the outer column 21 .

The outer column 21 is made of a steel pipe having a diameter larger than that of the inner column 22, which will be described later.
The lower end portion 21b of the outer pillar 21 is fixed to the building skeleton by being joined to the foundation beam 3B.
The upper end portion 21a of the outer pillar 21 is fixed to the building skeleton by being joined to the upper floor beam 3A on the upper floor side of the foundation beam 3B.
Furthermore, inside the outer pillar 21, an inner diaphragm 25 formed annularly along the inner wall surface is joined to the inner wall surface of the flange joint portion of the beam 3 of each floor.

The inner pillar 22 is made of a steel pipe having a diameter smaller than that of the outer pillar 21. The inner diaphragm 25A on the upper floor beam 3A side and the inner diaphragm 25B on the base beam 3B side have openings 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Aa, 25Ba is inserted inside the outer column 21. As shown in FIG. The inner pillar 22 is provided from a lower end portion 22b fixed to the base beam 3B side to an upper end portion 22a extending to the upper story beam 3A side.

The lower end portion 22b of the inner pillar 22 is fitted into the opening 25Ba of the inner diaphragm 25B on the side of the foundation beam 3B, thereby serving as a fixed portion fixed to the building skeleton. That is, the inner diameter of the opening 25Ba of the inner diaphragm 25B is set to be substantially the same as the outer diameter of the lower end 22b of the inner column 22. As shown in FIG. Furthermore, the lower surface of the inner diaphragm 25B is formed in a cylindrical shape with a bottom into which the lower end of the inner column 22 inserted through the opening 25Ba is inserted, and a receiving portion 35 for supporting the inner column 22 is joined. ing.

The upper end portion 22a of the inner pillar 22 is inserted through the opening 25Aa of the inner diaphragm 25A on the side of the upper floor beam 3A, and a gap 30 is formed between the edge of the opening 25Aa and the outer surface of the inner pillar 22. As a result, it becomes a non-fixed part separated from the outer pillar 21 with a gap 30 interposed therebetween without being fixed to the building skeleton. That is, the inner diameter of the opening 25Aa of the inner diaphragm 25A is set larger than the outer diameter of the upper end 22a of the inner pillar 22 by twice the width of the gap 30. As shown in FIG.

By adopting the above configuration, the steel pipe column structure 20 can suitably prevent plastic buckling due to the deformation concentration phenomenon while adopting a rational configuration that is excellent in terms of cost and workability. .
1 and 3, normally neither the vertical load nor the horizontal load of the building is transmitted to the inner pillars 22, and the upper floor beams 3A and It is borne by the outer pillars 21 fixed to the foundation beams 3B. Then, the inner pillar 22 is simply inserted into the outer pillar 21 and fixed to the building frame via the inner diaphragm 25B and the outer pillar 21 using only the lower end 22b as a fixing portion. can be installed. Furthermore, unlike the case where braces are provided, the inner pillars 22 do not normally bear vertical or horizontal loads, so they do not affect the structural design such as the floor plan of the building. On the other hand, the outer pillar 21 can be installed easily and inexpensively as a general steel pipe pillar that bears both the vertical load and the horizontal load.

On the other hand, as shown by the solid lines in FIGS. 2 and 3, during a major earthquake, when the outer pillars 21, which bear the vertical load, bend in an arc as the shaking progresses due to the horizontal load F, the inner pillars 22 are damaged. The upper end portion 22a, which is a fixed portion, contacts the inner surface of the outer column 21, more specifically, the edge of the opening 25Aa of the inner diaphragm 25A, thereby restraining the outer column 21 from bending more than a certain amount. As a result, the plastic buckling due to the deformation concentration phenomenon of the outer column 21 is preferably prevented. Furthermore, since the inner pillar 22 does not bear a vertical load, it exhibits a large bending rigidity and can appropriately restrain the bending of the outer pillar 21 .

[Another embodiment]
Another embodiment of the present invention will be described. It should be noted that the configuration of each embodiment described below is not limited to being applied alone, and can be applied in combination with the configurations of other embodiments.

(1) In the above-described embodiment, the lower end portion 22b of the inner pillar 22 is fixed to the building frame as a fixed portion, and the upper end portion 22a of the inner pillar 22 is not fixed to the building frame as a non-fixed portion. In contrast, the lower end 22b of the inner pillar 22 is not fixed to the building frame as a non-fixable portion, and is separated from the outer pillar 21 with the gap 30 interposed. 22 may be configured to be fixed to the building frame by using the upper end portion 22a as a fixing portion.

(2) In the above-described embodiment, the inner pillar 22 is inserted into the opening 25Aa of the inner diaphragm 25A of the outer pillar 21 to form the non-fixed portion (upper end portion 22a) that is not fixed to the building frame. was inserted to form a gap 30 between the edge of the opening 25Aa and the outer surface of the inner pillar 22, but the inner diaphragm 25A was omitted and the inner surface of the outer pillar 21 and the outer surface of the inner pillar 22 were separated. The non-fixed portion may be configured in a form in which a gap is formed between them.

(3) In the above embodiment, the inner pillars 22 are fixed on the side of the foundation beam 3B provided on the floor of the first floor, and are not fixed on the side of the upper beam 3A provided on the floor of the second floor. Although it is configured to extend from the beam 3B side to the upper floor beam 3A side, the installation range of the inner pillar 22 in the pillar 2 may be a range that lengthens the pillar. can be changed as appropriate. For example, the fixed part of the inner pillar 22 may be the beam side of the floor of the second floor or higher, and the non-fixed part of the inner pillar 22 may be the beam side of the floor of the third floor or higher. can be done. Further, the position of the fixed part and the non-fixed part of the inner pillar 22 can be set to the intermediate part between the upper and lower beams instead of the connecting part side of the beam of the pillar 2 .

(4) In the above embodiment, the lower end portion 22b, which is the fixed portion of the inner pillar 22, is fitted into the opening 25Ba of the inner diaphragm 25B on the side of the foundation beam 3B, and the fixed portion of the inner pillar 22 is attached to the building frame. However, for example, the fixed part of the inner pillar 22 is fixed to the building frame by welding the lower end 22b, which is the fixed part of the inner pillar 22, to the opening 25Ba of the inner diaphragm 25B on the side of the foundation beam 3B. The fixing method can be changed as appropriate.

1 Building 3A upper floor beam (upper floor side)
3B foundation beam (foundation)
20 Steel pipe column structure 21 Outer column 21a Upper end 21b Lower end 22 Inner column 22a Upper end 22b Lower end 25 Inner diaphragm 25A Inner diaphragm 25Aa Opening 25B Inner diaphragm 25Ba Opening 30 Gap

Claims (3)

A steel pipe column structure comprising a steel pipe outer column and an inner column inserted inside the outer column,
Both the upper end and the lower end of the outer pillar are fixed to the building frame,
In the inner pillar, one of the upper end portion and the lower end portion is fixed to the building frame as a fixed portion, and the other is not fixed to the building frame as a non-fixed portion, and a gap is interposed with respect to the outer pillar. A steel tube column structure that is spaced apart. In the non-fixed portion of the inner column, the inner column is inserted through an opening formed in the inner diaphragm of the outer column, and the gap is formed between the edge of the opening and the outer surface of the inner column. The steel pipe column structure of claim 1, wherein the steel pipe column structure is formed. 3. The steel pipe column structure according to claim 1 or 2, wherein the inner pillar is provided from a lower end portion fixed to the foundation portion as the fixed portion to an upper end portion extending to the upper floor side as the non-fixed portion. .

Images