JP4100245B2 - Column structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a column structure used for a structure including a reinforced concrete column and a reinforced concrete beam in which a steel pipe covers the upper surface of a floor slab to the lower end of an upper floor beam.
[0002]
[Prior art]
A concrete-filled steel pipe column in which concrete is filled in a steel pipe is known to have excellent deformation performance as compared with a normal reinforced concrete column. For concrete-filled steel tubular columns, if reinforced concrete is used for the beam, the normal reinforced concrete construction procedure can be applied to the beam as it is, and costs can be reduced compared to the case of using steel beams. it can.
In such a joint portion between a concrete-filled steel pipe column and a beam, both end portions of the column main bars penetrating the column beam joint portion in the vertical direction are inserted into the steel pipe of the column and fixed (see Patent Document 1). .)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-229495 (page 2-3, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the above structure, there is a problem that the resistance to the tensile force is small because the central part of the inner height of the column is unreasonable. Furthermore, when the fireproof coating is omitted, there is also a problem that the load supporting function at the time of fire is greatly reduced.
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a column structure that is excellent in yield strength and deformation performance, has good workability, and is inexpensive.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the column structure according to the present invention is a column structure used for a structure including a reinforced concrete column and a reinforced concrete beam covered with a steel pipe from the upper surface of the floor slab to the lower end of the upper floor beam. The column main reinforcement in the column has a discontinuous portion that penetrates the joint portion of the column beam up and down and becomes a non- barbed portion at the center of the floor, and the vertical direction of the discontinuous portion The height is arranged so as not to overlap with the height in the vertical direction of the discontinuous portion of the adjacent column main reinforcement.
Here, the discontinuous part means that the first column main reinforcement that extends up and down through the upper floor column beam joint and the lower column beam joint up and down. Since the second column main reinforcement that penetrates and extends to the center of the floor does not form a joint, it is the unreasonable portion that occurs between the lower end of the first column main reinforcement and the upper end of the second column main reinforcement. It is. The floor height is the height from the floor surface of a certain floor to the floor surface of the directly upper floor, and the height in the vertical direction is the height from the floor surface.
According to the present invention, the same mechanism as that of the lap joint is formed by making the vertical heights of the discontinuous portions of the column main bars the same for all the column main bars, but by making the height difference. That is, by providing a difference in height between the discontinuous portions of the column main bars, tensile stress can be transmitted between the adjacent column main bars through the concrete between the column main bars. Further, in the present invention, since the column main bars are not joined, there is no problem in construction even if the main bar length and the main bar arrangement are deviated to some extent.
Moreover, in the column structure which concerns on this invention, you may have a protruding part like a rib in the inner surface of the said steel pipe.
According to the present invention, the adhesion between the concrete and the steel pipe is increased by providing the inner surface of the steel pipe with a rib. In addition, the stress acting on the column main reinforcement that penetrates the upper floor column beam joints up and down to the center of the floor height is applied to the lower beam column joints via ribbed steel pipes. Since it is transmitted to the column main bars penetrating up and down and extending to the center part of the floor height, even when a tensile force acts, it is not necessary to join the column main bars.
Alternatively, in the column structure according to the present invention, instead of the ribbed steel pipe, a plate-like body such as a flat plate or a rod-like body such as a reinforcing bar may protrude from the inner surface of the steel pipe by a fixing means such as welding.
In the column structure according to the present invention, the steel pipe may be in contact with the beam via an elastic body such as rubber provided at the upper and lower ends of the steel pipe.
According to the present invention, by providing an elastic body such as rubber at the upper and lower ends of the steel pipe, the steel pipe does not come into contact with the beam, so that the concrete of the beam can be prevented from being crushed by the support pressure of the steel pipe. Furthermore, in this invention, since a steel pipe resists a shearing force but does not bear an axial force, a steel pipe with a thin wall thickness of about 6 to 9 mm can be used. Thereby, the weight of the steel pipe is reduced, transportation and lifting are facilitated, and cost reduction is achieved.
Moreover, in the column structure according to the present invention, the hoops at both ends in the axial direction of the column may be arranged denser than the hoops at the center in the axial direction of the column.
At the upper and lower ends of the steel pipe, the effect of restraining the concrete by the steel pipe is small, and the hoop bars are densely arranged at the upper and lower ends of the column as compared with the central portion of the column.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1: shows 1st embodiment of the column structure which concerns on this invention, (a) is a sectional elevation, (b) is an aa arrow directional view, (c) is a bb arrow. FIG. 4D is a cross-sectional view of the lower end portion of the steel pipe. In FIG. 1A, the beam reinforcement and the hoop reinforcement of the upper and lower floor columns are omitted.
As shown in FIG. 1 (a), a column structure 21 according to the present invention includes a reinforced concrete column 1 covered with a steel pipe 4 from the upper surface of a floor slab to the lower end of an upper floor beam 2, and a reinforced concrete beam 2. It is used for structures. In the column 1, a plurality of column main bars 5 are arranged at predetermined intervals along the inner peripheral surface of the steel pipe 4, and these pass through the column beam joint portion up and down. It extends to the high center. The lower end of the column main reinforcement 5 that penetrates the joint part of the upper-level column beam and the upper end of the column reinforcement 5 that penetrates the connection part of the lower-level column beam are not joined and have an unstriped portion. ing. Furthermore, consideration is given so that the vertical height of the unreasonable portion does not overlap between adjacent column main bars 5.
The column main reinforcing bars 5 are constrained by hoop bars 6 arranged at predetermined intervals in the column axis direction. As shown in FIG. 1C, the hoop muscle 6 at the center in the column axis direction is perpendicular to the first hoop muscle 6a surrounding the column main muscle 5 and the first hoop muscle 6a in the horizontal plane. 5 and a second hoop line 6b surrounding a part of the line. On the other hand, as shown in FIG. 1B, the hoop muscles 6 at both ends in the column axis direction include, in addition to the configuration of the hoop muscle 6 at the center in the column axis direction, a third hoop muscle 6c that surrounds all the column main muscles 5. It is composed of And as for the space | interval of these hoop muscles 6, the column axial direction both ends are narrow compared with the column axial direction center part. This is because the hoop bars 6 are arranged more densely at the upper and lower ends of the column 1 than at the center of the column 1 because the restraining effect of the concrete 3 by the steel tube 4 is small at the upper and lower ends of the steel tube 4.
As shown in FIGS. 1C and 1D, the steel pipe 4 is a square steel pipe having a thickness of about 9 mm. There is a gap of about 5 mm between the steel pipe 4 and the reinforced concrete beam 2, and a rubber 7 is attached between them. The rubber 7 used here is a urethane-based or styrene-based synthetic rubber that is excellent in durability and hardly affected by creep or the like.
Next, the effect | action by the structure of this embodiment is demonstrated.
The vertical heights of the discontinuous portions of the column main reinforcement 5 are not made the same for all the column main reinforcements 5 but by making the height difference, the adjacent columns via the concrete 3 between the column main reinforcements 5 are used. A tensile stress is transmitted between the main bars 5 and a mechanism similar to that of the lap joint is formed. In addition, the bending moment of a column at the time of an earthquake is generally an antisymmetrical shape that is large at the top of the column and the column base and small at the center. Therefore, also in this invention, the discontinuous part of the column main reinforcement 5 is arrange | positioned in the center part of floor height.
By providing the rubber 7 at the upper and lower ends of the steel pipe 4, the steel pipe 4 does not come into contact with the beam 2, thereby preventing the concrete 3 of the beam 2 from being crushed by the support pressure of the steel pipe 4.
In the column structure 21 according to the present embodiment, by making a vertical difference in the height in the vertical direction of the discontinuous portion of the column main reinforcement 5, there is no danger cross section due to no stripes at any height of the column 1, and there is no fireproof coating. However, the load support function in the event of a fire can be maintained. Moreover, in this invention, since the column main reinforcement 5 is not joined, even if the length and arrangement | positioning of the column main reinforcement 5 have shifted | deviated to some extent, it will not produce trouble on construction. Furthermore, since the steel pipe 4 having a thin wall thickness can be used, the weight of the steel pipe 4 is reduced, transportation and lifting are facilitated, and cost reduction is achieved.
[0007]
Further, in the column structure 21 according to the present invention, the column main reinforcement 5 extending vertically to the center of the upper level column beam and the column beam of the lower level up and down the column beam 21 on the upper floor. The number of main bars and / or the main bar diameter may be changed with the column main bars 5 extending through to the center of the floor height.
According to the present invention, when the cross-sectional force acting on the column 1 changes greatly between the upper part and the lower part of the column 1, the number of main bars and / or the main bar diameter is changed with the discontinuous portion of the column main bar 5 as a boundary. Therefore, a rational design is possible.
[0008]
Further, in the column structure 21 according to the present invention, the column main reinforcement 5 extending vertically to the center of the upper level column beam and the column beam of the lower level up and down the column beam 21 on the upper floor. The column main reinforcement 5 that penetrates through to the center of the floor height may be partly joined using joining means such as pressure welding, welding, or a mechanical joint.
According to the present invention, it is possible to resist a large tensile axial force by joining the column main reinforcement 5 from the joint portion of the upper-level column beam and a part of the column main reinforcement 5 from the connection portion of the lower-level column beam. can do.
[0009]
Next, a second embodiment of the present invention will be described. In the following drawings, the same components as those in the structure according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.
2A and 2B show a second embodiment of the column structure according to the present invention, in which FIG. 2A is a vertical sectional view, and FIG. 2B is a partially enlarged view of a steel pipe cross section.
As shown in FIG. 2A, in the column structure 22 according to the present invention, in addition to the configuration of the first embodiment, ribs 8 are provided on the inner periphery of the steel pipe 4 with a predetermined interval in the column axis direction. It is what. As shown in FIG.2 (b), the space | interval which arrange | positions the rib 8 to a column axial direction is 40 mm or less, and the height of the rib 8 is 2.5 mm or more.
According to the present invention, the adhesive force between the concrete 3 and the steel pipe 4 is increased by providing the inner surface of the steel pipe 4 with the rib 8. The stress acting on the column main reinforcing bars 5 extending vertically through the upper beam pillar joints and extending to the center of the floor height is connected to the lower beam joints via the steel pipes 4 with ribs 8. Therefore, even when a tensile force is applied, it is not necessary to join the column main bars 5 to each other.
[0010]
Alternatively, instead of the steel pipe with the ribs 8, a plate-like body or a rod-like body may be projected from the inner surface of the steel pipe. FIG. 3A is a partially enlarged view of a cross section of a steel pipe when a flat plate is welded to the inner surface of the steel pipe, and FIG. 3B is a partially enlarged view of a cross section of the steel pipe when welding a reinforcing bar to the inner surface of the steel pipe.
In the case of FIG. 3 (a), a plate 9 having a thickness of 9 mm is made into a ring shape and welded to the inner periphery of the steel pipe 4, or in a piece shape, for example, every 90 degrees with the central axis of the column 1 as the rotation axis, In addition, welding is performed at a predetermined interval in the column axis direction. On the other hand, in the case of FIG. 3 (b), the deformed rebar 10 of D13 is welded along the inner periphery of the steel pipe 4 and at a predetermined interval in the column axis direction.
Compared with the case where the steel pipe 4 having the ribs 8 is used, the cost can be reduced by retrofitting a plate-like body or a rod-like body to the steel pipe 4 by fixing means such as welding.
[0011]
【The invention's effect】
As described above, according to the present invention, an inexpensive column structure having excellent proof stress and deformation performance, good workability, and low cost can be realized.
[Brief description of the drawings]
FIG. 1 is a first embodiment of a column structure according to the present invention.
FIG. 2 is a second embodiment of a column structure according to the present invention.
FIG. 3 is a partially enlarged view of a cross section of a steel pipe in which a flat plate or a reinforcing bar is welded to the inner surface.
[Explanation of symbols]
1. Column 2 ... Beam 3 ... Concrete 4 ... Steel pipe 5 ... Column main bar 6 ... Hoop bar 6a ... First hoop bar 6b ... Second hoop bar 6c ... Third hoop bar 7 ... Rubber 8 ... Rib 9 ... Flat plate 10 ... Deformed bar 21 ... First embodiment of the column structure according to the present invention 22 ... Second embodiment of the column structure according to the present invention

Claims (6)

A column structure used for a structure including a reinforced concrete column and a reinforced concrete beam covered with a steel pipe from the upper surface of the floor slab to the lower end of the upper floor beam,
The column main reinforcing bar in the column has a discontinuous portion that vertically penetrates the joint portion of the column beam and becomes a non- muscle portion at the center of the floor, and the vertical height of the discontinuous portion Is arranged so as not to overlap with the vertical height of the discontinuous portions of the adjacent column main bars. The column structure according to claim 1,
A column structure having a protrusion on the inner surface of the steel pipe. The column structure according to claim 1,
A column structure having ribs on the inner surface of the steel pipe. The column structure according to claim 1,
A column structure characterized by projecting a plate-like body or a rod-like body on the inner surface of the steel pipe. In the pillar structure according to any one of claims 1 to 4,
The column structure, wherein the steel pipe is in contact with the beam through elastic bodies provided at upper and lower ends of the steel pipe. In the pillar structure according to any one of claims 1 to 5,
A column structure characterized in that hoop bars at both ends in the axial direction of the column are densely arranged as compared to hoop bars at an axially central portion of the column.

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