JPH0353418B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" This invention relates to the structure of a filled steel pipe concrete column used as a column of a building structure.

``Prior Art'' Conventionally, a typical filled steel pipe concrete column has a structure in which a simple right cylindrical steel pipe that also serves as a formwork is erected vertically, and concrete is simply poured inside the steel pipe. This structure consists of steel pipe columns filled with concrete, so the steel pipes and concrete are an integral structure as a whole. In addition, conventionally, as the structure of the joint part where a beam is joined to such a filled steel pipe concrete column, there is a structure on the outside of the joint between the filled steel pipe concrete column and the beam, which is made by pouring concrete inside the steel pipe. A stiffener ring is attached as an auxiliary member to provide rigidity.
A structure in which a beam is joined to this stiffener ring is known.

"Problems to be Solved by the Invention" However, in the structure of the conventional filled steel pipe concrete column, the steel pipe and concrete are integrated, and the beam is simply welded to the outer peripheral surface of the steel pipe. Therefore, the shear force acting on the beam is transmitted to the steel pipe as an axial force through the welded part between the beam and the steel pipe, and a part of this axial force is further transferred to the concrete as an axial force through the bonding surface between the steel pipe and concrete. It was beginning to be transmitted.

In this way, in conventional filled steel pipe concrete columns, the force transmission path from the beam to the column twists and turns, and moreover, the force is transmitted to the concrete inside the steel pipe via the bonding surface between the steel pipe and the concrete. . That is, the transmitted axial force is temporarily applied only to the steel pipe, and the steel pipe receives both axial stress and circumferential stress (ring tension) from the concrete. Therefore, the above-mentioned conventional filled steel pipe concrete columns tend to be in a plastic state under the Mises yield condition, and for this reason, the confining effect that should originally be brought about by steel pipes (the steel pipe is not able to absorb the axial force from the concrete filled inside it) (the effect of tightening the concrete against the force that it receives and tries to expand in the radial direction) can no longer be expected to sufficiently improve the compressive strength of the concrete, resulting in columns with a larger cross-sectional area than necessary. Another drawback was that the wall thickness of the steel pipe had to be increased.

In order to eliminate such conventional drawbacks, the applicant of the present invention first installed a
We are proposing a column-beam joint structure with fixed stiffeners in the shape of a planar cross.

As shown in FIGS. 6 and 7, this joint structure consists of a stiffener 4 which is constructed by assembling steel plates in a cross shape on the inside of the steel pipe 1 at the portion where the steel pipe 1 and the beams 2, 2 are connected. , each end of which is welded to the inner wall of the steel pipe 1, and is embedded in concrete 3 filled in the steel pipe 1. In this joint structure, the axial force transmitted from the beam 2 to the steel pipe 1 is extremely reduced by transmitting the shear force acting on the beam 2 directly to the concrete 3 as an axial force via the stiffener 4. This has an excellent effect in that when a ring tension is generated in the steel pipe 1 due to transverse strain in the concrete 3, a margin is created in the tolerance of the steel pipe 1 with respect to this ring tension.

The applicant of the present invention further conducted intensive research on the above-mentioned joint structure, and discovered points that should be improved in the above-mentioned joint structure.

That is, when constructing an architectural structure using the joint parts shown in FIGS. 6 and 7, the beam 2
Filled steel pipe concrete is constructed by pouring concrete inside the steel pipe 1 that has been joined.
The concrete is poured according to a procedure in which a tremie pipe is inserted into the inner bottom of the steel pipe 1 from the upper end opening of the steel pipe 1, and concrete is sequentially poured from the lower side inside the steel pipe. However, when inserting this tremie pipe, in the joint structure with the above configuration, since the cross-shaped stiffeners 4 are provided inside the steel pipe 1, it is necessary to insert concrete in a well-balanced manner within each area partitioned by the stiffeners 4. This makes it difficult to fill it sufficiently. Therefore, in order to place concrete in a well-balanced manner to every corner of each area, it is necessary to place four tremie pipes inside the steel pipes passing through each area around the stiffener 4 and filling them with concrete. arise. However, in this case, there are problems in terms of workability and economy because as many as four tremie tubes are used. In addition, in consideration of this point, for example, if concrete is poured in two diagonally located areas using two tremie pipes, the remaining two areas may not be filled with concrete in a well-balanced manner. will occur.

In addition, in the case of the above-mentioned shiiguchi structure, it is necessary to weld the stiffeners at the cross-shaped intersections and further weld each end to the inner wall of the steel pipe, which increases the number of welding points and takes time and effort. I had a problem.

The present invention has been made to solve the above-mentioned problems, and it is possible to enhance the confining effect brought about by the steel pipe, thereby reducing the cross-sectional area of the column, etc., and furthermore, it is possible to insert the tremie pipe into the center of the steel pipe and balance it. The purpose of the present invention is to provide a structure of a filled steel pipe concrete column that allows concrete to be placed well, enables the use of large-diameter tremie pipes, enables efficient filling of concrete, and facilitates welding. .

"Means for Solving the Problems" The present invention provides a structure for a filled steel pipe concrete column constructed by filling a steel pipe with concrete, in which the inner side of the steel pipe is located at a joint portion where the steel pipe and the beam are connected. An inner flange-type bearing pressure plate continuous along the inner periphery of the steel pipe and having an air vent hole is provided with its outer periphery fixed to the inner wall of the steel pipe and included in the concrete; The tremie pipe is unbonded to the concrete filled in the steel pipe at the interface to eliminate adhesion between the steel pipe and the concrete. In addition to allowing the use of large-diameter tremie pipes, the welding area can only be welded to the outer periphery.Furthermore, the air vent holes prevent air bubbles from remaining on the underside of the pressure plate, allowing the pressure plate to Transmits the shear force of the beam directly to the concrete as axial force.

At this time, the concrete part and the steel pipe part of the column are made to behave as separate bodies, and by having most of the shearing force transmitted to the concrete part be borne only by the concrete, the confining effect brought about by the steel pipe can be enhanced. I can do it.

Embodiment FIGS. 1 and 2 show an embodiment of a filled steel pipe concrete column according to the present invention, and show the joint portion thereof. The filled steel pipe concrete column according to this embodiment is applied to a building as shown in FIG. 4, for example. In FIG. 4, reference numeral 26 indicates a filled steel pipe concrete column (hereinafter abbreviated as column), 27 indicates a beam at each stage, and 28 indicates a joint.

As shown in FIGS. 1 and 2, the joint section 28 includes a steel pipe 10 that also serves as a formwork, a beam 27 fixed to the steel pipe 10, and a ring-shaped bearing plate provided inside the steel pipe 10. 11, 11, and concrete 12 which is filled inside the steel pipe 10 and includes the bearing plates 11, 11. Note that the bearing pressure plate 11
may be a polygonal flange type as will be explained later based on FIG.

The steel pipe 10 consists of a joined steel pipe 10a that is slightly longer than the back of the beam 27, and a connecting steel pipe 10b that has a length corresponding to the step height and is joined to the joined steel pipe 10a. Further, the steel pipe 10 and the concrete 12 are brought into an unbonded state (non-adhesive state) by interposing a separating material at the interface thereof.

The beam 27 has upper and lower flanges 27a, 27a.
and a web 27b, and the joined steel pipe 10a
It is welded to the outer peripheral surface and supported horizontally.

The bearing plate 11 is ring-shaped and has an outer diameter equal to the inner diameter of the joined steel pipe 10a, and is welded to the inner peripheral surface of the joined steel pipe 10a with each outer peripheral part at the same height as the flange 27a of the beam 27, It is fixed horizontally within the jointed steel pipe 10a. A plurality of air vent holes 11a are formed in the outer peripheral portion of the pressure-bearing plate 11 at required intervals in the circumferential direction of the pressure-bearing plate 11.

Next, construction work for the pillar 26 having the joint portion 28 will be explained.

As shown in FIG. 4, for example, a steel pipe 10 having a height of several stories is erected at a construction site with beams 27 fixed to the jointed steel pipe 10a at a predetermined position in the height direction. After the steel pipe 10 is erected,
The pillars 26 are constructed by filling them with concrete according to the procedure described below, and later another steel pipe 10 is added on top of the pillars 26 and filling with concrete is repeated.This process is repeated to construct the frame of the high-rise building. is what will be constructed.

In order to construct the column 26 by filling the steel pipe 10 erected as described above with concrete, a tremie pipe is inserted into the steel pipe 1 from the upper end of the steel pipe 10 erected at the construction site.
Insert it into the inner bottom of 0 and start pouring concrete. A separating material for unbonding the concrete to the steel pipe 10 can be provided on the steel pipe 10 in advance. In the work of inserting the tremie pipe, since the tremie pipe can be passed through the inside of the bearing pressure plate 11 and inserted into the center of the inside of the steel pipe 10, concrete can be filled from the center of the inside of the steel pipe 10, and the concrete can be uniformly filled. This enables easy filling work. Moreover, since a tremie pipe with a larger diameter can be used compared to the joint structure having the cross-shaped stiffener 4 shown in FIGS. 6 and 7, concrete can be filled efficiently.

The work of filling the inside of the steel pipe 10 with concrete is performed by gradually pulling up the tremie pipe T while maintaining an appropriate cover thickness so that the tip of the tremie pipe T does not come out of the concrete, as shown in Fig. 3. conduct. At this point, the concrete filled into the steel pipe 10 by the tremie pipe T approaches the bearing plate 11 as shown in FIG. 3, and further begins to surround the bearing plate 11 as shown by the two-dot chain line in FIG. Since the concrete forms a peak at the center of the steel pipe 10 and increases in volume as it swells, the bearing plate 1
There is a risk that there will be a portion on the lower surface of the outer periphery of the concrete that is not sufficiently covered. However, since there is an air vent hole 11a on the outer periphery of the bearing pressure plate 11, the air on the lower surface of the outer periphery of the bearing pressure plate 11 escapes upward through the air vent hole 11a, and then concrete fills this air vent hole 11a. Bearing plate 11
is completely surrounded by concrete. In this way, the presence of the air vent hole 11a allows the bearing plate 11 to be completely contained in the concrete during concrete filling, and the joint portion 28 is free from defects such as air bubbles.
It is possible to construct a column 26 having a .

In the joint section 28 constructed as described above, when a shearing force acts on the beam 27, this shearing force is transmitted from the beam 27 to the bearing plate 10 inside the beam 27 via the steel pipe 10.
1, and is further directly transmitted from the bearing plate 11 to the concrete 12. That is, the shearing force acting on the beam 27 can be made to act on the concrete 12 as an axial force. Moreover, since the concrete 12 is in an unbonded state with respect to the steel pipe 10,
A large axial force is no longer applied to the steel pipe 10 from the beam 27, and therefore, there is an allowance for the ring tension generated in the steel pipe 10 due to transverse strain of the concrete 12. Therefore,
In the case of the column 26 having the joint part 28 having the above-mentioned configuration, the confining effect of the steel pipe 10 is enhanced, resulting in a high compressive pressure resistance, and the cross-sectional area or the wall thickness of the steel pipe can be reduced. become.

Furthermore, since the bearing plate 11 can be fixed to the steel pipe 10 by welding only its outer peripheral portion to the steel pipe 10, there are fewer welding points and the welding work is easier compared to a structure in which a cross-shaped stiffener 4 is provided. .

By the way, if much of the shearing force from the beam 27 cannot be applied to the steel pipe 10 of the column 26,
When most of the shear force cannot be transmitted to the concrete 12 inside the steel pipe 10, the problem arises as to how to handle the axial force applied to the steel pipe 10. In that case, as shown in FIG. 4, a structure is provided in which a plurality of slits 30 extending in the circumferential direction of the steel pipe 10 are provided near the heightwise central portion 29 of the column 26 to make the steel pipe 10 slightly expandable and contractible. You should adopt. By performing such processing on the pillar 26,
The axial force can be prevented from being transmitted to the steel pipe 10, or even if it is transmitted, it can be absorbed by deformation of the portion of the steel pipe 10 where the slit 30 is formed, and the axial force can be borne by the concrete 12.

Fig. 5 shows an embodiment in which the present invention is applied to a filled steel pipe concrete column using a steel pipe 10' having a square cross section. A bearing plate 11' having a square outer circumferential shape is used. The inner peripheral shape of the bearing pressure plate 11' is formed into an octagonal shape in consideration of the strength of the bearing pressure plate 11'. The other configurations are the same as those of the embodiment described above, and the same effects as those of the embodiment described above can be obtained in this embodiment as well.

"Effects of the Invention" As explained above, the present invention is a filled steel pipe concrete column in which the concrete is unbonded to the steel pipe and a ring-shaped bearing plate is attached to the inside of the steel pipe. When placing concrete inside the steel pipe, it becomes possible to insert a thick tremie pipe into the center of the inside of the steel pipe, making it possible to fill the steel pipe with concrete uniformly and efficiently in a well-balanced manner. The bearing plate is designed to effectively transmit the shearing force acting on the beam to the concrete inside the steel pipe as axial force, and to prevent the axial force from being transmitted to the steel pipe as much as possible, allowing the steel pipe to better demonstrate its confided effect. This has the effect of improving the compressive strength of concrete and reducing the cross-sectional area of the columns. In addition, the air vent hole in the bearing plate bleeds air from the outer periphery of the lower surface of the bearing plate when filling with concrete, so concrete can be filled without creating air bubbles around the bearing plate, creating a joint with stable quality. There is an effect that can be done. Further, since the work of fixing the bearing pressure plate can be completed by welding the outer peripheral portion of the bearing pressure plate to the inner wall of the steel pipe, the work of attaching the bearing pressure plate is also easy.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining one embodiment of the present invention, in which Figure 1 is a vertical cross-sectional view of the joint part, Figure 2 is a cross-sectional view of the joint part, and Figure 3 is a cross-sectional view of the joint part. 4 is a side view showing a frame constructed using the filled steel pipe concrete column of this embodiment, and FIG. 5 is a sectional view showing a steel pipe being filled with concrete. FIG. 6 and 7 are cross-sectional views showing an example, and show the structure of a joint part related to a filled steel pipe concrete column previously proposed by the applicant, and FIG. 6 is a longitudinal sectional view, and FIG. is a cross-sectional view. 10, 10'... Steel pipe, 10a... Joined steel pipe,
10b... Connection steel pipe, 11, 11'... Bearing plate,
11a...Air vent hole, 12...Concrete,
26...Filled steel pipe concrete column (column), 27...
... Liang, 28... Shiguchi section.

Claims (1)

[Claims] 1 A structure of a filled steel pipe concrete column constructed by filling a steel pipe with concrete, where the steel pipe and the beam are connected at the joint part where the steel pipe is connected to the inside of the steel pipe and continues along the inner circumference of the steel pipe. and an inner flange type bearing plate having an air vent hole is provided with its outer peripheral portion fixed to the inner wall of the steel pipe and included in the concrete, and furthermore, the steel pipe and the concrete filled in the steel pipe are different from each other. , a structure of a filled steel pipe concrete column characterized in that the steel pipes and concrete are unbonded to each other at the interface to eliminate adhesion between the steel pipes and concrete.