JPH0649949A - Concrete structure enclosed in steel pipe - Google Patents

Abstract

PURPOSE:To provide a concrete structure enclosed in a steel pipe, which has high resistance resulting and a smaller sectional area. CONSTITUTION:A plurality of slits 1a,... extending to the peripheral direction of a steel pipe 1 are provided in the steel pipe 1 filled with concrete. The plurality of slits 1a,... extending to the periphery are arranged zigzag and the ends of the upper and lower slits are lapped in the peripheral direction to be extensible in the axial direction of the steel pipe 1. In this way, the steel pipe 1 does not bring about its partial buckling even when the compressive force in the axial direction exceeds a specified value and generates a confined effect and hence, increase of compressive resistance can be sufficiently expected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filled steel pipe concrete structure used for, for example, columns and piles of a building structure.

[0002]

2. Description of the Related Art Conventionally, as this type of filled steel pipe concrete structure, there is known a concrete structure in which a steel pipe also serving as a formwork is vertically installed and concrete is placed therein.
Since the filled steel pipe concrete structure is simply filled with concrete in the steel pipe, the steel pipe and the concrete are in a bonded state, and they mechanically behave integrally.

[0003]

However, in the above-mentioned conventional filled steel pipe concrete structure, the steel pipe and the concrete are in an adhered state and integrated. Therefore, when an axial compressive force acts on this filled steel pipe concrete structure, the steel pipe behaves as a unit with the concrete. Therefore, when the filled steel pipe concrete exceeds its predetermined compressive strength, the strain rate of the steel pipe and the concrete becomes extremely large. Then, the steel pipe causes local buckling or becomes plastic under the Mises yield condition. In addition, the concrete exceeds the compressive strength and reaches the descending area. Therefore, in the filled steel tube concrete structure, it is not possible to sufficiently expect that the compressive strength of concrete will increase due to the confined effect brought by the steel tube,
There is no choice but to use a pillar with a larger cross-sectional area than necessary. The present invention has been made in view of the above circumstances, and it is possible to sufficiently expect an increase in compression strength brought about by a filled steel tube concrete structure, and to reduce the cross-sectional area of the column as compared with the conventional one. It is intended to provide a structure.

[0004]

The present invention is a filled steel pipe concrete structure in which concrete is filled in a steel pipe, wherein the steel pipe is provided with a plurality of slits extending in the circumferential direction of the steel pipe. I am trying. In this invention,
When arranging multiple slits in a zigzag pattern so that the ends of the upper and lower slits wrap in the circumferential direction, and when reinforcing bars are reinforced in the concrete filled in the steel pipe or prestressing force is introduced. The member proof stress can be increased.

[0005]

According to the present invention, the above structure allows the steel pipe to freely expand and contract in the axial direction. Therefore, when the compressive force in the axial direction acts on the filled steel pipe concrete structure, the concrete is compressed, and when it exceeds a predetermined compressive strength, the concrete causes a large axial strain and the lateral strain starts to increase sharply. In addition, the steel pipe produces almost no axial strain and exhibits the confined effect of resisting lateral strain of concrete. That is, the axial force is received only by the concrete cross section, and the steel pipe receives the ring tension from the concrete as a reaction that gives the concrete a confined effect.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. FIG. 1 and FIG. 2 are views showing a first embodiment of the present invention, showing a filled steel pipe concrete structure.
3 and 4 are diagrams showing a second embodiment of the present invention,
5 and 6 are diagrams showing a third embodiment of the present invention.
7 to 9 are views showing a fourth embodiment of the present invention.

First, referring to FIGS. 1 and 2, reference numeral A indicates a column (hereinafter, abbreviated as column) of a filled steel pipe concrete structure. This pillar A is made up of a steel tube 1 as a frame, a diaphragm 2 made of paper sheets attached to its inner surface, concrete 3 filled therein, and a cylindrical shape formed at its end. And the space portion 4 of

Here, the steel pipe 1 is formed with linear slits 1a, 1a ... Which extend in the circumferential direction. The slits 1a, 1a ... Are arranged in a staggered pattern, and the ends of the upper and lower slits 1a, 1a ... Wrap in the circumferential direction by a dimension l, and the slits 1a, 1a. Are continuous in the circumferential direction. The slits 1a, 1a ... Are linear slits formed by extending the notches extending in the circumferential direction of the steel pipe 1 by pulling the steel pipe 1 in the direction of arrow p to extend the steel pipe 1. The diaphragm 2 made of paper sheets is for preventing the concrete 3 filled during construction from leaking from the slits 1a, 1a. Further, the cylindrical space 4 formed at the end of the steel pipe 1 is for grouting concrete or mortar into the steel pipe 1 when the steel pipe 1 is connected to another steel pipe.

In order to manufacture the column A, first, the steel pipe 1 having a plurality of linear notches 1a, 1a ... next,
The diaphragm 2 is attached to the inner surface of the steel pipe 1 to which elongation has been given.
Concrete 3 is filled into the steel pipe 1 to which the diaphragm 2 is attached. At this time, a space portion 4 for grout when connecting another steel pipe is formed at the end of the steel pipe 1.

In the pillar A thus manufactured, the steel pipe 1 is stretched in the axial direction (direction of arrow p) in advance,
Even if a great amount of strain is generated in the concrete 3 due to an axial compressive force acting on the pillar A, the steel pipe 1 only shrinks freely following it, and buckling does not occur. Therefore, the steel pipe 1 can be expected to have a confined effect on the concrete 3 with almost no axial force, and as a reaction thereof, receives only the ring tension. That is, the pillar A receives the axial force by the concrete 3 which is strong against compression, and the ring tension by the steel pipe which is strong against tension. As a result, steel pipe 1
The concrete and the concrete 3 make use of the characteristics of the steel pipe 1 which is strong against tension and the concrete 3 which is strong against compression. The steel pipe 1 gives the concrete 3 a confined effect, and the concrete 3 gives the steel pipe 1 a ring tension. .

Therefore, the column A will surely ensure a much higher compression strength than the conventional one due to the synergistic effect of the steel pipe 1 and the concrete 3, and the cross-sectional area can be made several times smaller. It will be possible.

Next, FIGS. 3 and 4 will be described. 3 and 4, the same components as those shown in FIGS. 1 and 2 are designated by the same reference numerals. In FIGS. 3 and 4, reference symbol B is a column (hereinafter abbreviated as column) of a filled steel pipe concrete structure in which reinforced concrete is contained, and reference symbol 5 is a reinforcing rod. The reinforcing bars 5, 5 ... Are arranged inside the steel pipe 1 along the circumferential direction before the concrete 3 is filled into the steel pipe 1. Concrete 3 is filled into the steel pipe 1 in which the reinforcing bars 5, 5 ... Therefore, the pillar B can have a higher member proof stress than the pillar A.

Further, FIGS. 5 and 6 will be described. 5 and 6, the same elements as those shown in FIGS. 3 and 4 are designated by the same reference numerals. 5 and 6, symbol C is a column of a filled steel pipe concrete structure (hereinafter abbreviated as column) in which prestressed concrete is contained, and symbol 6 is a sheath pipe.

In order to manufacture the pillar C, before the concrete 3 is filled in the steel pipe 1, the reinforcing pipes 5, 5, ... Simultaneously with the sheath pipes 6, 6 ,. The steel pipe 1 in which the sheath pipes 5, 5 ... And the sheath pipes 6, 6 are installed is filled with concrete 3. Next, a PC steel material (not shown) is passed through the sheath tubes 6, 6 ... Embedded in concrete. A prestressing force in the axial direction is introduced into the column C by applying tension to the PC steel material passed through after the concrete 3 has hardened.

Therefore, when the structure receives a seismic force to generate a falling moment and a tensile force acts on the column C, the tensile stress actually generated is a value obtained by subtracting the prestressing force. That is, the column C can be a filled steel pipe concrete structure having a higher member proof strength than the columns A and B.

Finally, FIGS. 7 to 9 will be described. 7 to 9, the same elements as those shown in FIGS. 1 and 2 are designated by the same reference numerals. In these figures, reference numeral D indicates a plurality of portions extending in the circumferential direction only in the substantially central portion between floors (inflection point of moment acting on pillar D when a building experiences a fall moment due to an earthquake etc.) It is a column of a filled steel pipe concrete structure provided with a slit (hereinafter abbreviated as a column). In addition, a separator (an application of grease, oil, etc., or a plastic film, etc.) between the steel pipe 1 and the concrete 3 to make them unbonded.
10 are provided. FIG. 9 is a diagram showing a state in which the pillar D is used as a pillar of an actual building. In this structure, the pillar D has the same action and effect as the pillar A.

In each of the above embodiments, the column of the filled steel pipe concrete structure can be used as the column of the flexible structure because the cross-sectional area thereof can be reduced. Its application range is considered to be a super high-rise building with a heavy and flexible structure, which is completely different from the conventional light and flexible structure. In addition, in order to achieve the structure formation in which the stress in the circumferential direction is generated in the steel pipe with almost no stress in the axial direction, when the slit alone is insufficient, grease or the like is applied to the inner surface of the steel pipe.

[0018]

As described above, according to the present invention, the steel pipe is provided with a plurality of slits extending in the circumferential direction thereof so that the steel pipe can freely shrink in the axial direction when an axial compressive force is exerted. Therefore, even if the concrete is largely distorted in the axial direction by the axial force, the steel pipe is not locally buckled or yielded. Ultimately, the axial force acts on the concrete which is strong against compression, and the steel tube which is strong against tension is made to exert only the ring tension as a reaction which causes the confined effect on the concrete. Therefore, in the conventional filled steel pipe concrete structure, it was not possible to sufficiently expect that the compressive strength of the concrete would increase due to the confined effect, but in the present invention, it becomes possible to expect that sufficiently, and the cross-sectional area of the column Can be made smaller.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a first embodiment of a filled steel pipe concrete structure of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a front sectional view showing a second embodiment of the filled steel pipe concrete structure of the present invention.

FIG. 4 is a sectional view taken along line YY in FIG.

FIG. 5 is a front sectional view showing a third embodiment of the filled steel pipe concrete structure of the present invention.

6 is a sectional view taken along line YY in FIG.

FIG. 7 is a front sectional view showing a fourth embodiment of the filled steel pipe concrete structure of the present invention.

8 is a plan sectional view of FIG.

9 is an explanatory diagram showing a state in which the filled steel pipe concrete structure shown in FIG. 7 is applied to a building.

[Explanation of symbols]

 1 Steel pipe 1a Slit 3 Concrete 5 Reinforcing bar 6 Sheath pipe

Claims (6)

[Claims] 1. A filled steel pipe concrete structure in which concrete is filled in a steel pipe, wherein the steel pipe is provided with a plurality of slits extending in the circumferential direction of the steel pipe. 2. The filled steel pipe according to claim 1, wherein a plurality of slits extending in the circumferential direction of the steel pipe are arranged in a staggered manner, and ends of the upper and lower slits are wrapped in the circumferential direction. Concrete structure. 3. The filled steel pipe concrete structure according to claim 1, characterized in that reinforcing bars are arranged in the concrete filled in the steel pipe. 4. The filled steel pipe concrete structure according to claim 1, wherein a prestressing force is introduced into the concrete. 5. The filled steel pipe concrete structure according to claim 1, wherein a plurality of slits extending in the circumferential direction are provided only in a substantially central portion between the floors. 6. The filled steel pipe concrete structure according to any one of claims 1 to 5, wherein a separator for eliminating adhesion of concrete is formed on the inner surface of the steel pipe.