JP5532852B2 - Steel pipe concrete pillar - Google Patents

Description

  The present invention relates to a steel pipe concrete column in which concrete is filled in a steel pipe.

In recent years, steel pipe concrete columns (hereinafter also referred to as CFT columns) have been used as structural materials for structures. This CFT column is formed by filling concrete inside the steel pipe. Since the inner concrete and the outer steel pipe are bound to each other, the strength of the steel pipe is strong and the concrete is strong in compressive force. The advantage of is synergistically utilized. As a result, the structure has characteristics such as high bending strength and less local buckling.
However, the CFT pillar may collapse during a fire as will be described later. For this reason, it is preferable to apply a fireproof coating to the CFT column in the same manner as a normal steel column in order to improve the fireproof performance, but in this case, the amount of the fireproof coating is increased.
Therefore, a CFT column has been proposed in which a reinforcing bar is reinforced by a reinforcing bar when the steel pipe on the outer periphery of the column loses the proof stress by arranging a reinforcing bar inside the steel pipe (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 5-280096

  In the above-mentioned CFT column, it is necessary to reinforce the steel pipe inside the steel pipe after manufacturing the steel pipe at the steel production factory, and insert the reinforcing bar into the steel pipe and secure the cover thickness. The operations such as connecting the main muscles were complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a steel pipe concrete column that can reduce fireproof coating and can be easily manufactured. .

In order to achieve such an object, the steel pipe concrete column of the present invention is a steel pipe concrete column filled with concrete inside the steel pipe, and is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and other than the plurality of locations. Then, a reinforcing body that is not in contact with the steel pipe is provided inside the steel pipe, and the reinforcing body is a steel rib formed along the axial direction of the steel pipe concrete column .

In such a steel pipe concrete column, it is desirable that a joint portion of the steel pipe concrete column with the steel beam does not have the reinforcing body and is provided with a fireproof coating.
According to such a steel pipe concrete column, it is possible to reduce the work man-hour at the time of manufacturing the column.

In this steel pipe concrete column, the joining portion has a diaphragm in which a through hole for filling the concrete is formed, the steel pipe is joined to the diaphragm, and the reinforcing body is not joined to the diaphragm. Also good.
According to such a steel pipe concrete column, it is possible to make the production easier.

Also, a steel pipe concrete column filled with concrete inside the steel pipe, which is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and a reinforcing body that is not in contact with the steel pipe at other locations than the plurality of locations is provided with the steel pipe. Of the steel pipe concrete column, the joint portion with the steel beam is not provided with the reinforcing body and is provided with a fireproof coating, and the joint portion is a through hole for filling the concrete. The steel pipe is joined to the diaphragm, the reinforcing body is non-joined to the diaphragm, and the joining portion among the plurality of places where the steel pipe and the reinforcing body are joined. The fireproof coating is applied to the steel pipe from the nearest location to the joint.

Also, a steel pipe concrete column filled with concrete inside the steel pipe, which is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and a reinforcing body that is not in contact with the steel pipe at other locations than the plurality of locations is provided with the steel pipe. Of the steel pipe concrete column, the joint portion with the steel beam is not provided with the reinforcing body and is provided with a fireproof coating, and the joint portion is a through hole for filling the concrete. The reinforcing body is joined to the diaphragm.

  According to the present invention, the fireproof coating can be reduced, and the production can be easily performed.

It is a plane sectional view of the CFT pillar of a reference example. FIG. 2A to FIG. 2C are conceptual diagrams for explaining thermal degradation during fire of the CFT pillar of the reference example. It is explanatory drawing of the junction structure of the CFT pillar and girder of a 1st embodiment. It is a plane sectional view of the pillar part of the CFT pillar of a 1st embodiment. It is a perspective view of a joint part. 6A to 6C are explanatory views of the CFT pillar manufacturing method according to the first embodiment. It is explanatory drawing of the junction structure of the CFT pillar of 2nd Embodiment, and a big beam. 8A to 8E are explanatory views of the CFT pillar manufacturing method according to the second embodiment. 9A to 9D are explanatory views of a modified example of the CFT pillar manufacturing method according to the second embodiment. It is explanatory drawing of the relationship between a column site joining location and moment force. It is another explanatory drawing of the relationship between a column site joining location and moment force.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a reference example will be described before describing this embodiment.

≪Reference example≫
FIG. 1 is a plan sectional view of a steel pipe concrete (CFT) column of a reference example.
As shown in FIG. 1, the CFT column of the reference example is formed by filling a concrete pipe 200 inside a steel pipe 100 having a square cross section. In other words, the outer surface of the CFT pillar concrete 200 is covered with the steel pipe 100. The concrete 200 has a smaller thermal diffusivity than the steel pipe 100.

  Moreover, FIG. 2A-FIG. 2C are the conceptual diagrams for demonstrating the thermal deterioration at the time of the fire of the CFT pillar of a reference example.

Normally (at room temperature), as shown in FIG. 2A, the CFT column supports the load by integrating the steel pipe 100 and the concrete 200 as a composite structure.
When a fire occurs (initial stage at the time of fire), the temperature of the steel pipe 100 on the outer periphery of the CFT column rises. On the other hand, since the concrete 200 in the CFT column has a low thermal diffusivity, the temperature hardly rises on the center side of the CFT column. As a result, as shown in FIG. 2B, the amount of expansion deformation of the steel pipe 100 with respect to the axial direction (arrow direction) of the CFT column becomes larger than the amount of expansion deformation of the concrete 200, and the steel pipe 100 bears a load.

When the fire continues (mid-fire period), the load on the steel pipe 100 is increased, and the steel pipe 100 deteriorates due to heat (thermal deterioration). As shown in FIG. Bending occurs. When local buckling occurs in this way, the load cannot be supported by the steel pipe 100, and the concrete 200 supports the entire load.
When the fire continues (at the end of the fire), the concrete 200 also thermally deteriorates as the temperature rises, and eventually the concrete 200 cannot support the load and the CFT column collapses.

  Thus, even the CFT pillar may collapse during a fire. Therefore, it is preferable to apply a fireproof coating to the CFT column in the same manner as a normal steel column. In this case, however, a large amount of fireproof coating is required.

  In addition, when a steel pipe on the outer periphery of a column loses its proof strength by placing a reinforcing bar inside the steel pipe, a CFT column has been proposed in which the proof strength is reinforced by the reinforcing bar. There is a problem that the work of arranging the reinforcing bars is necessary, and the work of inserting the reinforcing bars into the steel pipe, ensuring the cover thickness, and connecting the main bars is complicated.

  Therefore, in this embodiment, the fireproof performance of the CFT pillar is improved to reduce the fireproof coating, and the pillar is easily manufactured.

<< First Embodiment >>
FIG. 3 is an explanatory diagram of a joint structure between the CFT pillar and the large beam according to the first embodiment.
As shown in the figure, the CFT column 10 of this embodiment is joined to a large beam 20 (corresponding to a steel beam) at a joint 12 (corresponding to a joint). In the following description, a portion other than the joint portion 12 in the CFT column 10 is referred to as a column portion 11. Further, as shown in the figure, a fireproof coating 30 is applied to the ends of the large beam 20, the joint portion 12, and the column portion 11.

FIG. 4 is a plan sectional view of the column portion 11 of the CFT column 10 of the first embodiment.
The column part 11 of this embodiment has a steel pipe 110 and a rib 112. The steel pipe 110 has a square cross section similar to the steel pipe 100 of the reference example. The rib 112 is made of steel, and is provided inside the steel pipe 110 along the length direction of the steel pipe 110 (that is, the axial direction of the CFT column 10). As shown in FIG. 3, the rib 112 is joined to the steel pipe 110 at the end in the length direction of the column portion 11 (near the joint portion 12). In addition, the rib 112 is not in contact with the steel pipe 110 except for this joint location.
The steel pipe 110 is filled with concrete 200.

The joint 12 has a steel pipe 120 and a diaphragm 122.
FIG. 5 is a perspective view of the joint portion 12.

  The steel pipe 120 has a square cross section similar to the steel pipe 110. However, the steel pipe 120 is shorter in the axial direction of the column than the steel pipe 110. The diaphragm 122 is a steel plate in which a circular through hole 12a for filling the concrete 200 is formed at the center, and is joined to the steel pipe 120 by welding. As shown in FIG. 3, the joint portion 12 is provided with a fireproof coating 30, so that it is not necessary to provide a reinforcing body (rib) inside the steel pipe 120. Thereby, it is possible to reduce the work man-hour of manufacture of the joint part 12.

  The large beam 20 is a steel frame beam having a cross section, for example, and is joined to the joint portion 12 of the CFT column 10 by welding.

  The fire-resistant coating 30 is, for example, calcium silicate board, gypsum board, rock wool, fire-resistant paint, and the like, and is provided in order to improve fire resistance. In the present embodiment, a fireproof coating 30 is applied to the joint portion 12 and the girder 20. Furthermore, in this embodiment, the fireproof coating 30 is also applied to the steel pipe 110 (in the range indicated by H in the figure) from the joining portion of the steel pipe 110 and the rib 112 to the joint portion 12 in the column portion 11. In this embodiment, since the rib 112 and the joint portion 12 (diaphragm 122) are not joined in this embodiment, if the portion of the steel pipe 110 in the range indicated by H in the figure is thermally deteriorated in the event of a fire, the strength of the rib 112 This is because it becomes impossible to reinforce. In the present embodiment, since the fireproof coating 30 is applied to the portion H, the proof stress can be reliably reinforced by the rib 112 in the event of a fire. Usually, in the range of H at the upper end of the beam flange, there is floor slab concrete, which is protected from heat. Therefore, in many cases where there is a floor slab, the fireproof coating 30 is unnecessary. However, if the welded length of the rib 112 and the steel pipe 110 exceeds the floor slab thickness (goes out above the top of the floor slab), adiabatic protection is performed by the fireproof coating 30.

  Thus, in the CFT column 10 of this embodiment, the rib 112 is provided in the inner surface of the steel pipe 110 of the column part 11 among the CFT columns 10, and the rib 112 is an end part in the length direction of the column part 11 ( It is joined to the steel pipe 110 at both ends), and is not in contact with the steel pipe 110 except for the joint location. And the concrete 200 with small heat conductivity is filled inside the steel pipe 110.

  With the above configuration, the proof strength can be reinforced by the rib 112 even if the steel pipe 110 loses the proof strength in the event of a fire. Therefore, since the pillar part 11 (except for the part H in FIG. 3) can be made non-fireproof coating, the fireproof coating can be reduced.

<About production method>
Next, a manufacturing method of the CFT pillar 10 of the first embodiment will be described.
6A to 6C are explanatory views of the CFT pillar manufacturing method according to the first embodiment.

First, as shown in FIG. 6A, after manufacturing the steel pipe 110, ribs 112 having both ends formed in an L shape are inserted into the steel pipe 110.
And as shown to FIG. 6B, the edge part of the rib 112 is joined to the inner peripheral surface of the edge part of the steel pipe 110 length direction by welding (thick line part of a figure). As a result, both ends are joined to the steel pipe 110, and ribs 112 that are not in contact with the steel pipe 110 can be provided inside the steel pipe 110 at other locations.
Thereafter, as shown in FIG. 6C in the factory, the column portion 11 is joined to the diaphragm 122 of the joint portion 12 by welding, and the concrete 200 is filled in the site at the site.

  As described above, in this embodiment, the rib 112 is provided on the inner surface of the steel pipe 110 of the column part 11. The ribs 112 are connected to the steel pipe 110 at both ends in the length direction of the column part 11, and are not in contact with the steel pipe 110 at other locations. In addition, a fireproof coating 30 is applied to the joint portion between the rib 112 and the steel pipe 110. Therefore, since the rib 112 becomes difficult to be influenced by external heat, the proof strength can be reinforced by the rib 112 even if the steel pipe 110 on the outer periphery of the column portion 11 loses the proof strength in the event of a fire. Thereby, since the pillar part 11 can be made into a fireproof coating, it is possible to reduce a fireproof coating.

  Moreover, in this embodiment, the rib 112 can be joined when manufacturing the steel pipe 110 in a factory. Therefore, the CFT column 10 can be easily manufactured as compared with the case where reinforcing bars are arranged in the steel pipe.

<< Second Embodiment >>
FIG. 7 is an explanatory diagram of a joint structure between the CFT pillar and the large beam according to the second embodiment. In FIG. 7, parts having the same configuration as in FIG.

Also in the CFT column 10 of the second embodiment, a rib 112 is provided in the column portion 11 as in the first embodiment, and this rib 112 is an end portion in the length direction of the column portion 11 and the inner periphery of the steel pipe 110. It is joined to the surface.
However, in the second embodiment, the rib 112 is also joined to the diaphragm 122 of the joint portion 12. Thus, in 2nd Embodiment, since the rib 112 and the diaphragm 122 have joined, even if the steel pipe 110 of the column part 11 is thermally deteriorated completely, proof strength can be reinforced with the rib 112. FIG. For this reason, in 2nd Embodiment, the fireproof coating 30 is given only to the joint part 12 and the big beam 20, and the column part 11 is a fireproof coating. Therefore, in the second embodiment, the fireproof coating can be further reduced.

<About production method>
8A to 8E are explanatory views of the CFT pillar manufacturing method according to the second embodiment.
First, as shown in FIG. 8A, after manufacturing the steel pipe 110, ribs 112 having both ends formed in an L shape are inserted into the steel pipe 110. In the second embodiment, the overall length of the steel pipe 110 and the length of the rib 112 are equal.
And as shown to FIG. 8B, the edge part of the rib 112 is joined to the internal peripheral surface of the both ends of the steel pipe 110 length direction by welding. Thereby, the column part 11 is formed.
Furthermore, in 2nd Embodiment, as shown to FIG. 8C, the diaphragm 122 is joined to the both ends of the pillar part 11 by welding. Then, as shown in FIG. 8D, the rib 112 in the steel pipe 110 and the diaphragm 122 are joined by welding using the through-hole 12a (see FIG. 5) of the diaphragm 122.
Then, in the factory, as shown in FIG. 8E, the diaphragm 112 and the steel pipe 120 are joined together by welding, and the concrete 200 is filled in the interior at the site.

Thus, in 2nd Embodiment, in addition to joining the rib 112 with the steel pipe 110, the rib 112 is joined also to the diaphragm 122 of the joint part 12. FIG. Thereby, the pillar part 11 can be made into a fireproof coating completely, and reduction of a fireproof coating can further be aimed at.
The rib 112 and the diaphragm 122 can be easily joined using the through-hole 12a for filling the concrete of the diaphragm 122.

<< Modification of Second Embodiment >>
9A to 9D are explanatory views of a modified example of the CFT pillar manufacturing method according to the second embodiment.
In this modification, a steel pipe 110A and a steel pipe 110B having a shorter overall length (for example, half the length) than the steel pipe 110 are used as the steel pipe of the column portion 11. Moreover, the rib 112A and the rib 112B of the length corresponding to each full length of the steel pipe 110A and the steel pipe 110B are used.

In this modified example, as shown in FIG. 9A, first, one end of the rib 112 </ b> A is welded to the diaphragm 122. Similarly, one end of the rib 112B is welded to the diaphragm 122.
9B, the rib 112A joined to the diaphragm 122 is inserted into the steel pipe 110A. Similarly, the rib 112B is inserted into the steel pipe 110B.
After the insertion, as shown in FIG. 9C, the diaphragm 122 and the steel pipe 110A are joined by welding. Further, the other end of the rib 112A and the inner peripheral surface of the steel pipe 110A are joined by welding. Similarly, the diaphragm 122 and the steel pipe 110B are joined by welding, and the other end of the rib 112B and the inner peripheral surface of the steel pipe 110B are joined by welding.
Then, as shown in FIG. 9D, the ends of the steel pipe 110A and the steel pipe 110B are joined by welding.

Also in this modified example, the pillar portion 11 can be completely made of a fireproof coating, and the fireproof coating can be reduced.
Moreover, in this modification, since the rib 112A (112B) and the diaphragm 122 are joined in advance, the production of the CFT pillar 10 can be simplified.

  In each of the above-described embodiments, when the column portion 11 of the CFT column 10 is composed of a plurality of steel pipes and the upper and lower steel pipes are joined at the site, the joint location (hereinafter also referred to as the column site joint location) The ribs in the steel pipe cannot be joined. In such a case, the column site joint cannot transmit the moment force that acts on the frame during a fire.

  FIG.10 and FIG.11 is explanatory drawing of the relationship between a pillar site joining location and moment force. Note that the left side of FIGS. 10 and 11 is a diagram showing the joint structure of the CFT column 10 and the large beam 20, and the right side is a diagram showing the moment force.

  In the case of FIG. 10, the moment force becomes zero at a position close to the lower large beam 20 (for example, a position about 1 meter above the lower large beam 20). In this case, the moment force at the column head is larger than the column base, and the column head requires a larger cross section than the column base, but can resist the force acting in the event of a fire as a frame. In addition, when the column site joint is provided near the center of the floor height as shown in FIG. 11, the moment force of the column base and the column head is substantially the same, and the column base and the column head have the same cross section. Economic design can be done.

  As described above, even when the ribs are not joined at the column site joint location, when the steel pipe on the surface of the pillar portion 11 is thermally deteriorated, the proof stress can be secured by the ribs and the concrete in the steel pipe.

  The above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

  For example, in the above-described embodiment, the CFT pillar 10 has a square cross section, but may have a round shape. In the above-described embodiment, one rib 112 is provided for each side of the CFT pillar 10, but a plurality of ribs 112 may be provided for each side. In addition, proof stress can be improved more by forming many ribs 112. FIG. In the above-described embodiment, the rib 112 of the FB material (flat bar material) is provided inside the steel pipe 110. However, the present invention is not limited to this. For example, a CT material or an angle material (L material) is provided inside the steel pipe 110. May be provided.

  Further, in the above-described embodiment, the pillar portion 11 is configured as a fireproof coating, but the thickness of the fireproof coating 30 may be made thinner than other portions. Even in this case, the fireproof coating can be reduced.

10 CFT pillars, 11 pillars,
12 spout, 12a through hole,
20 beams, 30 fireproof coating,
100, 110, 120 steel pipes,
112 ribs, 122 diaphragms,
200 concrete

Claims (5)

A steel pipe concrete column filled with concrete inside the steel pipe,
The steel pipe is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and a reinforcing body that is not in contact with the steel pipe is provided inside the steel pipe at a location other than the plurality of locations .
The steel pipe concrete column, wherein the reinforcing body is a steel rib formed along the axial direction of the steel pipe concrete column. It is a steel pipe concrete pillar according to claim 1 ,
The steel pipe concrete pillar characterized by not having the reinforcing body at a joint portion of the steel pipe concrete pillar with the steel beam and having a fireproof coating. It is a steel pipe concrete pillar according to claim 2 ,
The joint has a diaphragm in which a through hole for filling the concrete is formed,
The steel pipe concrete column, wherein the steel pipe is joined to the diaphragm, and the reinforcing body is not joined to the diaphragm. A steel pipe concrete column filled with concrete inside the steel pipe,
The steel pipe is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and a reinforcing body that is not in contact with the steel pipe is provided inside the steel pipe at a location other than the plurality of locations.
There is no reinforcing body at the joint portion of the steel pipe concrete column with the steel beam, and a fireproof coating is applied,
The joint has a diaphragm in which a through hole for filling the concrete is formed,
The steel pipe is joined to the diaphragm, and the reinforcing body is non-joined to the diaphragm;
The steel pipe concrete pillar, wherein the fireproof coating is applied to the steel pipe from the place closest to the joint to the joint among the plurality of places where the steel pipe and the reinforcing body are joined. A steel pipe concrete column filled with concrete inside the steel pipe,
The steel pipe is joined to the inner peripheral surface of the steel pipe at a plurality of locations, and a reinforcing body that is not in contact with the steel pipe is provided inside the steel pipe at a location other than the plurality of locations.
There is no reinforcing body at the joint portion of the steel pipe concrete column with the steel beam, and a fireproof coating is applied,
The joint has a diaphragm in which a through hole for filling the concrete is formed,
The steel pipe concrete column, wherein the reinforcing body is joined to the diaphragm.

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