JP2011111729A - Joint structure of steel pipe concrete column and steel-framed beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a steel pipe concrete column and a steel-framed beam, which enables fireproof coating to be reduced and reduces man-hours for working. <P>SOLUTION: In this joint structure of a steel pipe concrete column formed by filling the inside of a steel pipe with concrete and a steel-framed beam, ribs are formed on the inner surface of the steel pipe at the unjoined part of the steel pipe concrete column with the steel-framed beam, and no rib is formed on the inner surface of the steel pipe at the joint part of the steel pipe concrete column and the steel-framed beam. The joint part and the steel-framed beam are coated for fireproofness. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a joint structure between a steel pipe concrete column filled with concrete inside a steel pipe and a steel beam.

  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.

  Further, in such a CFT column, there has been proposed one in which a rib is provided on the inner surface of the steel pipe along the length direction (axial direction) of the column to improve the strength (see, for example, Patent Document 1). ).

JP-A-4-52353

As will be described later, 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 order to improve the fireproof performance. However, in this case, there is a problem that the amount of the fireproof coating is increased.
Moreover, in the CFT pillar mentioned above, the rib is provided also in the junction part with a steel beam. This joint is manufactured separately from the other parts of the pillar. Therefore, if a rib is provided at the joint, the number of work steps increases.

  The present invention has been made in view of the problems as described above, and its purpose is to join a steel pipe concrete column and a steel beam that can reduce the fireproof coating and reduce the number of work steps. To provide a structure.

In order to achieve such an object, the joining structure of a steel pipe concrete column and a steel beam according to the present invention is a joining structure of a steel pipe concrete column filled with concrete in a steel pipe and a steel beam, The non-joint portion of the steel beam has a rib on the inner surface of the steel pipe, the joint portion of the steel pipe concrete column and the steel beam has no rib on the inner surface of the steel pipe, and the joint portion and The steel beam is fire-resistant coated.
According to such a joint structure between a steel pipe concrete column and a steel beam, the fireproof coating can be reduced, and the number of work steps can be reduced.

In this joining structure of a steel pipe concrete column and a steel beam, the rib is preferably provided along the axial direction of the steel pipe concrete column.
According to such a joint structure between a steel pipe concrete column and a steel beam, the proof stress can be improved and the concrete can be efficiently filled.

In this structure, the steel pipe concrete column and the steel beam may be joined, and the rib may be unjoined from the joint.
According to such a joint structure between a steel pipe concrete column and a steel beam, it is possible to further reduce the work man-hours.

It is desirable that the steel pipe concrete column and the steel beam have a joint structure in which a heat conductive material is mixed in the concrete. Moreover, it is desirable that the heat conducting material is silicon carbide.
According to such a joint structure between a steel pipe concrete column and a steel beam, the fire resistance performance of the steel pipe concrete column can be improved.

  According to the present invention, the fireproof coating can be reduced, and the number of work steps can be reduced.

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 of this embodiment, and a big beam. It is a plane sectional view of the pillar part of this embodiment. It is a perspective view of the joint part of this embodiment. It is explanatory drawing of an example of the manufacturing method of a pillar part. It is explanatory drawing of another manufacturing method of a pillar part.

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. Therefore, in this embodiment, the fire resistance performance of the CFT pillar is improved to reduce the fire resistance coating.

<< this embodiment >>
FIG. 3 is an explanatory diagram of a joint structure between the CFT pillar and the large beam according to the present 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 of the CFT column 10 other than the joint portion 12 is referred to as a column portion 11 (corresponding to a non-joined portion). Further, as shown in the figure, a fireproof coating 30 is applied to the girder 20 and the joint 12.

FIG. 4 is a plan sectional view of the column portion 11 of the CFT columns 10 of the present 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 protrudes from the inner surface of the steel pipe 110. The rib 112 is provided along the length direction of the steel pipe 110 (that is, the axial direction of the CFT column 10). The steel pipe 110 is filled with concrete 200. In the present embodiment, silicon carbide having high thermal conductivity is mixed in the concrete 200.

  In the present embodiment, the rib 112 having a high thermal diffusivity (that is, having a high thermal conductivity) is protruded from the inner surface of the steel pipe 110. Therefore, in the event of a fire, the heat on the outer periphery of the steel pipe 110 is transmitted through the rib 112 to It is transmitted to the concrete 200 having a large heat capacity. Moreover, since the silicon carbide with high heat conductivity is mixed in the concrete 200, the heat from the steel pipe 110 (and the rib 112) can be further transmitted to the inner side. Thereby, compared with the case of a reference example, the temperature difference in the outer peripheral part of a pillar and an inside becomes small, and the raise of the temperature of the steel pipe 110 is suppressed. Therefore, at the time of a fire, the steel pipe 110 can be prevented from buckling locally as shown in FIG. 2B, and the fire resistance performance is improved.

  As described above, in this embodiment, by providing the rib 112 on the inner surface of the steel pipe 110 of the column part 11, the fire resistance performance of the column part 11 is improved as compared with the case of the reference example. Is not necessary. Therefore, since the pillar part 11 can be made into a fireproof coating, the fireproof coating can be reduced.

  In addition, in this embodiment, although the pillar part 11 is made into non-fireproof coating, you may make it make the fireproof coating to the pillar part 11 thinner than another part (large beam 20 or joint part 12). Even in this case, the fireproof coating can be reduced.

The joint portion 12 includes a steel pipe 120 and a diaphragm 122.
FIG. 5 is a perspective view of the joint portion 12 of the present embodiment.
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, and no rib is provided on the inner surface of the steel pipe 120. 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. In addition, since the steel pipe 120 of the joint part 12 does not have a rib as described above, the joint part 12 is worse in fire resistance than the column part 11. Therefore, as shown in FIG. 3, the spout 12 is provided with a fireproof coating 30.

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.

  As described above, in the CFT column 10 of the present embodiment, the rib 112 is provided on the inner surface of the steel pipe 110 of the column portion 11 of the CFT column 10 and the rib is not provided on the inner surface of the steel tube 120 of the joint portion 12. The joint portion 12 and the girder 20 are provided with a fireproof coating 30, whereas the column portion 11 has a fireproof coating.

<About production method>
6A to 6D are explanatory diagrams of an example of a manufacturing method of the column portion 11.
First, as shown in FIG. 6A, the rib 112 is welded in advance along the longitudinal direction of the flat steel plate 110 ′. Then, the steel plate 110 ′ is bent as shown in FIG. 6B, and the ends of the steel plate 110 ′ are welded as shown in FIG. 6C. Thereby, the column part 11 is formed.

7A and 7B are explanatory diagrams of another manufacturing method of the column portion 11. FIG.
First, as shown in FIG. 7A, ribs 112 are previously welded to a steel plate 110a, a steel plate 110b, a steel plate 110c, and a steel plate 110d corresponding to each side of the steel pipe 110, respectively. And as shown to FIG. 7B, the steel plate 110a, the steel plate 110b, the steel plate 110c, and the steel plate 110d are each welded.
In addition, manufacture of the column part 11 as mentioned above is performed in a factory. And the pillar part 11 is joined with the joint part 12 by welding in a factory.

  The joint 12 is manufactured separately from the pillar 11 in the factory. First, the steel pipe 120 is formed from a flat steel plate in the same manner as the column part 11, and the diaphragm 122 is welded to the steel pipe 120 to form the joint part 12.

  If ribs are provided on the inner surface of the steel pipe 120 of the joint portion 12 in the same manner as the column portion 11, the number of work steps for manufacturing the joint portion 12 increases. On the other hand, in this embodiment, since the rib 12 is not provided in the joint part 12, it is possible to reduce the work man-hour concerning manufacture of the CFT pillar 10. FIG.

  Thus, the column part 11 and the joint part 12 are manufactured separately in a factory, and are joined by welding in a factory. Specifically, the diaphragm 122 of the joint portion 12 and the end portion of the steel pipe 110 of the column portion 11 are joined by welding. In the present embodiment, each rib 112 of the pillar portion 11 is not joined to the diaphragm 122, but the end portion of each rib 112 and the diaphragm 122 may be joined. In addition, since the location of welding will be reduced if each rib 112 and the diaphragm 122 are made non-joining like this embodiment, work man-hours can be reduced more.

  After that, the concrete 200 is filled into the column part 11 and the joint part 12. The concrete 200 is filled into the pillar portion 11 and the joint portion 12 through the through hole 12a of the joint portion 12. In addition, since the rib 112 of the pillar part 11 is formed in the axial direction of the CFT pillar 10, the concrete 200 can be efficiently filled. Thereby, the CFT pillar 10 is formed. Further, the large beam 20 is joined to the joint portion 12, and the fireproof coating 30 is applied to the joint portion 12 and the large beam 20.

  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. Thereby, the heat of the steel pipe 110 of the column part 11 can be transmitted to the concrete 200 with a large heat capacity, and the temperature difference between the inside and the outside of the column part 11 can be reduced. Therefore, the thermal expansion of the steel pipe 110 can be suppressed, and the fire resistance performance of the column portion 11 of the CFT column 10 can be improved. Thereby, it is not necessary to apply fireproof coating to the column part 11, and the fireproof coating can be reduced.

  Further, by providing the rib 112 on the inner surface of the steel pipe 110, a stiffening effect against local buckling of the steel pipe 110 can be expected, and as a result, the steel pipe 110 is thermally expanded and bears most of the axial force. The effect of delaying the occurrence time of local buckling that occurs in a state (a condition in which buckling is likely to occur under high axial stress), and the effect of improving the residual yield strength (stable yield strength) after buckling can be expected. Thereby, fireproof time can be lengthened and fireproof performance can be improved.

  Also, the rib 112 itself arranged in the axial direction of the column is welded to the inner surface of the steel pipe 110 (the temperature is likely to rise), but it is possible to bear the axial stress. This can contribute to an increase in the force supportable time, that is, an improvement in the fireproof time (fireproof performance).

  Further, no rib is provided on the inner surface of the steel pipe 120 of the joint portion 12. Thereby, the work man-hour of manufacture of the CFT pillar 10 can be reduced.

  In this embodiment, silicon carbide is mixed in the concrete 200. Thereby, the thermal conductivity of the concrete 200 can be improved and the fire resistance can be further improved.

  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 this embodiment, the CFT pillar 10 has a square cross section, but may have a round shape. In the present 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, fire resistance can be improved more by forming many ribs 112. In the present embodiment, the FB material (flat bar material) rib 112 is provided inside the steel pipe 110. However, the present invention is not limited to this, and for example, a CT material or an angle material (L material) may be used.

  In this embodiment, silicon carbide is mixed in the concrete 200 as a heat conductive material, but another heat conductive material (for example, carbon particles) may be mixed.

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

Claims (5)

A steel pipe concrete column filled with concrete in a steel pipe and a joint structure of a steel beam,
Of the steel pipe concrete columns, there is a rib on the inner surface of the steel pipe in the non-joined portion with the steel beam, and there is no rib on the inner surface of the steel pipe in the joined portion between the steel pipe concrete column and the steel beam, and The joint and the steel beam are fireproof coated,
A joint structure between a steel pipe concrete column and a steel beam. It is a joining structure of a steel pipe concrete column and a steel beam according to claim 1,
The said rib is provided along the axial direction of the said steel pipe concrete pillar, The joining structure of the steel pipe concrete pillar and steel beam characterized by the above-mentioned. It is a joining structure of a steel pipe concrete column and a steel beam according to claim 1 or claim 2,
The said rib is non-joining with the said junction part, The joining structure of the steel pipe concrete pillar and steel beam characterized by the above-mentioned. A joint structure between a steel pipe concrete column and a steel beam according to any one of claims 1 to 3,
A joining structure of a steel pipe concrete column and a steel beam, wherein the concrete is mixed with a heat conductive material. A steel pipe concrete column and a steel beam joint structure according to claim 4,
The joint structure of a steel pipe concrete column and a steel beam, wherein the heat conductive material is silicon carbide.

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