JP7460168B2 - reinforced concrete column - Google Patents

Description

The present invention relates to reinforced concrete columns, and more particularly to reinforced concrete columns having shear reinforcement.

Square column members used in reinforced concrete columns are required to have sufficient strength and toughness. When the shear stress applied to a column member increases, the shear reinforcing bars (peripheral reinforcement) placed along the outer periphery of the column member alone do not have enough bearing capacity. The lack of durability has been compensated for (for example, see Patent Document 1). This core muscle is known to be effective in contributing not only to yield strength but also to toughness. That is, the core reinforcement in a rectangular column member is expected to have two types of effects: ensuring strength and toughness.

As buildings become increasingly taller, square column components will need to be able to withstand high axial forces. As high axial forces (axial compressive stress in the column cross section) are required, it becomes necessary to ensure not only shear strength but also deformation performance, which requires more shear reinforcement and a higher shear reinforcement ratio PW.

Figure 8 shows the cross section of a conventional rectangular columnar member. As the column axial force increases, the stress in the direction perpendicular to the column axial force (shear stress direction, directions A and B in Figure 8) increases, as in the rectangular columnar member 101 shown in Figure 8. This causes the column side cross section to be pushed out to the side, i.e., the column side bulges, as shown by the two-dot chain line in Figure 8.

To suppress this phenomenon, two rectangular, mutually perpendicular, straight core bars 103a, 103b (hereinafter sometimes collectively referred to as straight core bars 103) have traditionally been placed inside the peripheral bars 102, with the straight core bars 103 being configured to bear the shear strength. The straight core bars 103 suppress bulging, while at the same time resisting the deformation (distortion) that would cause this bulging, delaying destruction from the bulge. This effect is known as the toughness effect of the core bars.

If the axial force increases further, the elongation of the linear core bars 103 increases, and when the shear strength reaches its limit, it causes the component to break. It is believed that suppressing the elongation of the linear core bars 103 can further improve the toughness of the rectangular column members 101 when high axial forces are generated, and it is hoped that this will lead to further developments in improving the earthquake resistance of rectangular column members 101 used in high-rise buildings.

Therefore, as the required column axial force (high axial force) and shear stress increase, conventionally, in order to resist in the applied direction, many linear core reinforcements 103 are inserted as shown in FIG. was. However, although it is possible to resist shear strength by inserting a large number of linear core reinforcements 103, there is a limit to toughness performance. In other words, since the elongation (strain) of the core muscle increases with applied force, it was necessary to take its limits into consideration.

JP 2006-249860 A

The object of the present invention is to provide a reinforced concrete column with shear reinforcement that can maintain the ductility performance while retaining the shear strength of the column member, even during a major earthquake, for example.

The above-mentioned problem is solved by the reinforced concrete column of the present invention, which comprises a reinforced concrete column having a square cross section, which is arranged along the periphery of the reinforced concrete column and surrounds a plurality of column main reinforcements, a first central reinforcement arranged inside the periphery reinforcement and formed in a circle, and a second central reinforcement formed in the same shape as the first central reinforcement, wherein the diameter of the circle of the first central reinforcement is the same as the length of one side of the periphery reinforcement, the first central reinforcement is arranged above the periphery reinforcement and the first central reinforcement and the periphery reinforcement are in contact with each other at four points , and the second central reinforcement is arranged below the periphery reinforcement and the second central reinforcement and the periphery reinforcement are in contact with each other at four points .
Furthermore, the above-mentioned problem is solved by the reinforced concrete column of the present invention, which is a reinforced concrete column having a square cross section, comprising: a rectangular peripheral reinforcement arranged along the periphery of the reinforced concrete column and surrounding a plurality of column main reinforcements; a first central reinforcement arranged inside the peripheral reinforcement and formed in a circle; and a second central reinforcement formed in the same shape as the first central reinforcement, wherein the diameter of the circle of the first central reinforcement is the same as the length of one side of the peripheral reinforcement, the first central reinforcement and the peripheral reinforcement are in contact with each other at four points, the peripheral reinforcement and the first central reinforcement are arranged in groups on the axis of the reinforced concrete column, and in each group, the peripheral reinforcement and the first central reinforcement are arranged integrally, and the second central reinforcement is arranged between adjacent groups at a predetermined distance from the peripheral reinforcement.

In such reinforced concrete columns, by providing circular core reinforcement that contacts the outer reinforcement at four points, when a high axial force is applied, the resistance to shear stress is reduced in the centrifugal direction even when used in combination with circular core reinforcement. comes to act on the stress of Therefore, the tensile stress of the circular core reinforcement acts to tighten the cylindrical part of the concrete (the inner part of the circular core reinforcement) as a reaction force to the stress acting in the centrifugal direction. This action suppresses the bulge on the sides of the column due to the generation of high axial force. By making the core reinforcement circular, it is possible to suppress the bulge on the sides with fewer parts compared to conventional straight core reinforcement, making it possible to maintain toughness while maintaining shear strength. becomes.
In addition, by arranging a second core reinforcement that has the same shape as the core reinforcement, that is, the same circular shape, it is possible to prevent the occurrence of damage to the circular or elliptical portions of the concrete when high axial force is applied. The restraint force that tightens the inner part of the child muscle increases, and the resistance and restraint performance can be further improved.
Further, by assembling the outer reinforcing bars and the core reinforcing bars, the workability of the column member in a factory or on site is improved. Note that the core muscle may be arranged independently of the outer circumferential muscle.

In this case, the outer perimeter reinforcement and the first core reinforcement are preferably welded or tied at the four contact points. By welding or bundling the outer perimeter reinforcement and the first core reinforcement, the outer perimeter reinforcement and the first core reinforcement can be moved together, and can be easily installed during construction. In addition, the shear reinforcement integrated by welding the outer perimeter reinforcement and the first core reinforcement improves the shear strength.

At this time, the peripheral reinforcement , the first core reinforcement , and the second core reinforcement are preferably formed from high-strength reinforcing bars having a yield point of 590 to 1275 N/mm ² .
By forming the outer circumferential reinforcing bars , the first core reinforcing bars , and the second core reinforcing bars from high-strength reinforcing bars, it is possible to improve the shear strength without increasing the cross section of the column member.

At this time, the outer circumferential reinforcement and the core reinforcement are closed-type reinforcing bars, and a plurality of the outer peripheral reinforcement and the core reinforcement are provided in pairs, and in each set, the outer peripheral reinforcement and the core reinforcement are provided in plurality. It is preferable that the fibers are arranged integrally with the muscles.
By using the outer reinforcing bars and the core reinforcing bars as closed reinforcing bars, and combining them into sets, the workability of the column member in a factory or on-site is improved. Note that the core muscle may be arranged independently of the outer circumferential muscle.

The reinforced concrete column of the present invention makes it possible to provide a reinforced concrete column having shear reinforcement that can maintain the ductility performance while maintaining the shear strength of the column member.

1 is a perspective view of a reinforced concrete column according to an embodiment of the present invention, with a part of the concrete cut away. FIG. FIG. 2 is an elevational view taken along arrow II in FIG. 1 , showing the arrangement of reinforcement in a reinforced concrete column. 3 is a cross-sectional view of the reinforced concrete column taken along line III-III in FIG. 2. It is an explanatory view showing a peripheral reinforcement and a circular core reinforcement used in a reinforced concrete column. FIG. 2 is an explanatory diagram showing the stress that acts when a high axial force is applied to a reinforced concrete column. FIG. 1 is an explanatory diagram showing the effect of tightening concrete by circular core bars. 6A is an enlarged view showing part C in FIG. 6A. FIG. FIG. 11 is an elevational view showing a modified example of reinforcement of a reinforced concrete column. It is an elevation view showing a modification of reinforcement of a reinforced concrete column. FIG. 1 is a cross-sectional view of a conventional reinforced concrete column, illustrating a state where a high axial force is applied. FIG. 4 is a cross-sectional view showing the reinforcement of a reinforced concrete column according to a second embodiment of the present invention. FIG. 10 is an elevational view taken along the arrow X in FIG. 9 , showing the reinforcement of a reinforced concrete column according to a second embodiment. 10 is an elevational view seen from arrow view XI in FIG. 9. FIG.

<<First embodiment>>
A reinforced concrete column 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Note that the members and arrangements described below do not limit the present invention, and various modifications can be made within the scope of the present invention.

In this specification, the terms indicating directions are defined according to the arrows shown in Figure 1. Specifically, in the following explanation, the "front-rear direction" refers to the thickness direction of the reinforced concrete column 1, which is the X direction in Figure 1. Additionally, the "width direction" refers to the horizontal direction of the reinforced concrete column 1, which is the Y direction in Figure 1. Additionally, the "up-down direction" and "vertical direction" refer to the Z direction in Figure 1, which is the height direction of the reinforced concrete column 1. In addition, in this specification, the expression "○ mm to △ mm" means more than ○ mm and less than △ mm.

The reinforced concrete column 1 is a column used in high-rise buildings such as condominiums and office buildings, and has increased strength and toughness by arranging reinforcing bars in a virtual cylindrical shape on a concrete column.
The reinforced concrete column 1 of the first embodiment is a column member of concrete 4 having a rectangular cross section, as shown in FIGS. 1 to 3. The reinforced concrete column 1 includes a plurality of column main reinforcements 11 arranged along its outer periphery and extending in the axial direction (Z direction) of the column, and a plurality of peripheral reinforcements 2 and circular core reinforcements 3 surrounding them. ing.

Of the multiple column main bars 11, column main bar 11a is a reinforcing bar arranged at the corner of the reinforced concrete column 1, and column main bar 11b is a reinforcing bar arranged near the corner. Column main bar 11c is a reinforcing bar arranged inside the circular core bar 3 near the center of the four sides. Column main bars 11a to 11c may be collectively referred to as column main bars 11.

A reinforced concrete column 1 is provided with an outer circumferential reinforcement 2 and a circular core reinforcement 3 as shear reinforcing bars. The outer circumferential reinforcement 2 is a shear reinforcing reinforcement arranged along the outer periphery of the reinforced concrete column 1 and formed into a rectangular shape in plan view. Further, the circular core reinforcement 3 is a shear reinforcing reinforcement that is arranged to overlap the outer peripheral reinforcement 2 and is circular in plan view.

2 to 4, the length L of one side (hoop side length) of the peripheral reinforcing bars 2 and the diameter R of the circular core reinforcing bars 3 (circular hoop) are formed to be the same size. The peripheral reinforcing bars 2 and the circular core reinforcing bars 3 are in contact with each other at four contact points 5. More specifically, the circular core reinforcing bars 3 are arranged so that the peripheral reinforcing bars 2, the centers of each side of the peripheral reinforcing bars 2, the front-rear ends of the circular core reinforcing bars 3, and both ends of the circular core reinforcing bars 3 in the width direction are in contact with each other.
As shown in Fig. 1, the circular core bars 3 are in contact with the peripheral reinforcements 2, and as shown in Fig. 2, the circular core bars 3 are placed on the peripheral reinforcements 2 when viewed from the side. As shown in Fig. 4, the peripheral reinforcements 2 and the circular core bars 3 are arc-welded at four contact points (contact points 5). The peripheral reinforcements 2 and the circular core bars 3 may be tied together at the contact points 5 using a tie wire. As will be described later, the peripheral reinforcements 2 may be placed between two circular core bars 3 to form a set of shear reinforcements. The circular core bars 3 may also be placed independently of the peripheral reinforcements 2. In other words, the circular core bars 3 do not have to be placed directly on the peripheral reinforcements 2, and may be placed between the peripheral reinforcements 2 that are placed above and below at a predetermined interval P.

The outer circumferential reinforcement 2 and the circular core reinforcement 3 are closed type reinforcing bars, and by welding or bundling them at the four contact points 5, one peripheral reinforcement 2 (square hoop) and one circular core reinforcement 3 (circular hoops) can be arranged integrally as a set. In other words, each set consists of a total of two shear reinforcing bars, and as shown in FIGS. 1 and 2, the outer circumferential reinforcement 2 and circular core reinforcement 3 of each set are at approximately the same height within the reinforced concrete column 1. Reinforcement is placed in the center.

The rectangular peripheral reinforcements 2 are arranged so as to surround a plurality of column main reinforcements 11 arranged along the outer periphery of the reinforced concrete column 1, as shown in FIGS. 1 to 3. Further, the circular core reinforcements 3 surround the column main reinforcements 11c arranged at the center of the sides, excluding the column main reinforcements 11a at the corners and the column main reinforcements 11b near the corners, among the plurality of column main reinforcements 11. will be placed in
In addition, among the column main reinforcements 11, some of the column main reinforcements 11c on the four sides surrounded by the circular core reinforcements 3 are the column main reinforcements 11a arranged at the corner and near the corner, as shown in FIG. It is arranged closer to the inside of the reinforced concrete column 1 than 11b. Thereby, when the circular core reinforcement 3 is arranged, the circular core reinforcement 3 does not interfere with the column main reinforcement 11c.
Furthermore, high-strength reinforcing bars, such as MK785, having a yield point of 590 to 1275 N/mm ² may be used for the outer circumferential reinforcement 2 or the circular core reinforcement 3. High-strength reinforcing bars may be used for both the peripheral reinforcement 2 and the circular core reinforcement 3.

The effect of the circular core bar 3 used in the reinforced concrete column 1 will be explained below.
When designing a reinforced concrete building, the first consideration is to ensure shear strength in order to strengthen each structural member. In the case of column members, the shear strength is borne by shear reinforcing bars surrounding the outer periphery of the column cross section.

As the scale of a building increases, the shear stress acting on the column members also increases, and the shear strength of the shear reinforcement bars surrounding the periphery alone is insufficient. When the shear strength is insufficient, conventionally, as shown in Figure 8, a combination of elongated linear core bars 103a on one side and elongated linear core bars 103b on the other side is placed around the center of the cross section to add shear strength.
When the scale of a building becomes even larger, such as a high-rise building, high axial forces are generated in the column members. When a compressive axial force (vertical direction) is applied to a column member, the column member shrinks in the vertical direction (the direction of the applied force) and expands in the direction perpendicular to the applied force. The ratio of the vertical strain generated in the column member to the strain generated in the vertical direction is expressed as the Poisson's ratio.

As shown in Figure 8, when a high axial force is applied to a rectangular column member 101, which is a conventional reinforced concrete column, the force causes the column to bulge in the direction indicated by arrow D, causing the sides of the rectangular column member 101 to bulge outward (see the two-dot chain line in Figure 8). For example, when the Poisson's ratio is 0.2, a force of 0.2 times the high axial force is applied as the force causing the column to bulge outward. The peripheral reinforcement 102 arranged on the outside of the rectangular column member 101 resists the force causing the column to bulge outward. If a linear core reinforcement 103 is arranged in the center, the linear core reinforcement 103 will resist and suppress the phenomenon of the sides of the rectangular column member 101 bulging outward.

Conventionally, resistance to shear strength was achieved by inserting the linear core reinforcement 103 in this way. Stronger shear stress can be resisted by inserting more linear core reinforcements 103. However, although it can withstand shear stress when inserted in large numbers, there is a limit to its toughness. That is, since the elongation (strain) of the linear core muscle 103 increases with applied force, it was necessary to take its limits into consideration.

As shown in Fig. 4, the shear reinforcing bars used in the reinforced concrete column 1 are circular with a circumferential bar 2 that matches the outer circumference of the rectangular column and a diameter R that is the same as the length L of the side of the rectangular circumferential bar 2. It is constituted by a circular core muscle 3 formed.

By making the shear reinforcing bars circular like the circular core reinforcements 3, the concrete 4 within the circular core reinforcements 3 is tightened when a high axial force is applied. At this time, the force in the direction perpendicular to the high axial force (the force in the direction of arrow E that tends to expand shown in FIG. 5) is transformed into a circular centrifugal force. Since the stress acting in the centrifugal direction is circular, it is converted into a tensile stress in the axial direction of the circular core muscle 3 (arrow G shown in FIGS. 4A and 4B). Then, the same force F as the centrifugal force acts in the direction of the center of the circle as a reaction.
In other words, the applied force that causes the concrete 4 to expand due to the high axial force due to the circular core reinforcement 3 is the axial tensile stress of the circular core reinforcement 3, as shown by the dashed line H shown in FIGS. 4A and 4B. and begin to resist. The circular core muscle 3 acts in the same way as the so-called "wooden barrel wappa" action.

In the case of the conventional straight core bars 103a, 103b shown in FIG. 8, the effect of the straight core bars 103a, 103b on toughness is exerted only when strain is generated in the axial direction (longitudinal direction) of each bar.
On the other hand, the circular core bars 3 used in the reinforced concrete column 1 are also effective in the direction perpendicular to the load direction, so that one circular core bar 3 is effective as shear reinforcement in both the load direction and the direction perpendicular to it. In other words, by making the core bar circular, one circular core bar 3 exerts its effect as shear reinforcement in the X direction (front-back direction) and Y direction (left-right direction, width direction) in Fig. 3. Therefore, compared to the conventional linear core bars 103, which exert their effect only after strain is generated in the linear direction, the circular core bars 3 bulge outward only slightly.

Furthermore, for example, if a high-strength rebar with a tensile strength of 925 N/ ^mm2 is used for the circular core bar 3, the circular shape can be maintained up to the maximum tensile strength. As long as the circular core bar 3 does not rupture in tension, the distortion in the centrifugal direction (arrow E in Fig. 5) of the concrete part surrounded by the circular core bar 3 does not become large. In other words, the circular core bar 3 also suppresses the bulging phenomenon of the column side parts more efficiently than the conventional straight core bar 103.

In addition, as the axial force increases, the bulging of the column edges due to the high axial force also occurs in the direction perpendicular to the applied force. In other words, if we explain it in terms of Poisson's ratio, the application of axial force causes a bulge along the entire circumference in the direction perpendicular to the applied force. Therefore, the circular core bar 3 can resist forces applied perpendicular to the horizontal force during an earthquake.

In addition, by forming the core bars in a circular shape as described above, one circular core bar 3 (circular hoop) has the effect of suppressing bulging in both the X and Y directions. In the case of the conventional linear core bar 103, it was necessary to insert linear core bars 103a and 103b arranged in mutually perpendicular directions in order to resist stress in the perpendicular direction. Therefore, when comparing the length of the material used as the core bar (length of rebar), the total length of the circular core bar 3 is shorter than that of the linear core bars 103a and 103b, and the amount of rebar can be reduced by about 40%. Therefore, forming the core bar in a circular shape can reduce costs.
In other words, in the reinforced concrete column 1 shown in Figures 1 to 3, compared to the case where the conventional straight core bar 103 shown in Figure 8 is used, if the column dimensions are the same, the same effect of shear reinforcement can be obtained with a smaller amount of steel bar.
In addition, unlike the conventional method, the reinforcing bar arrangement does not require the linear core bars 103 to be placed one by one, which makes the construction easier and shortens the assembly time for the columns.

(Modification)
The basic set of shear reinforcement bars is a combination of one peripheral reinforcement bar 2 (square hoop) and one circular core reinforcement bar 3 (circular hoop) as shown in Figures 1 to 3, but if the required stress becomes even greater, the number of peripheral reinforcement bars 2 and circular core reinforcement bars 3 included in one set may be increased.

For example, as in the modification shown in FIG. 7A, a second circular core muscle 3b (second core muscle) formed in the same shape as the first circular core muscle 3a is connected to the outer circumferential core muscle 2. It may be placed below. In this way, by combining one outer circumferential reinforcement 2 and two circular core reinforcements 3a and 3b and configuring the three as one, it is possible to further improve the yield strength and restraining force performance. . Note that the interval (pitch P) between the sets of shear reinforcing bars is generally set to about 100 mm, for example.
Further, as in the modification shown in FIG. 7B, the outer circumferential reinforcement 2 and the first circular core reinforcement 3a are arranged at a predetermined interval (pitch P) as a set of shear reinforcing reinforcement, and apart from that, the second The circular core reinforcement 3b may be arranged between sets of shear reinforcing reinforcement arranged above and below. That is, the second circular core reinforcement 3b is arranged between the two outer peripheral reinforcements 2 arranged above and below. When the pitch P is 100 mm, the distance between the outer circumferential reinforcement 2 and the second circular core reinforcement 3b is approximately 50 mm. By arranging the second circular core reinforcement 3b in this way, the reinforcing bars are arranged in a more virtual cylindrical manner, and the toughness can be further improved.

As mentioned above, the effect of the circular core bars 3 is that when a high axial force is applied, they act like the "wrap of a wooden barrel", thereby suppressing concrete distortion in the axial compressive stress area surrounded by the circular core bars 3, and maintaining the circular shape. This has the opposite effect of suppressing the expansion of the circular cross-sectional area, acting to tighten it. Therefore, compared to conventional straight core bars, the amount of expansion of the circular core bars 3 is minimal.

<<Second embodiment>>
Next, a reinforced concrete column 201 according to a second embodiment of the present invention will be described with reference to Figs.
The reinforced concrete column 1 of the first embodiment has a square cross section, and uses a circular core bar 3 formed in a circular shape to match the cross section. However, many reinforced concrete columns actually used have a rectangular cross section. The shape of a rectangular column is permitted to have a rectangular cross section with a long side length D2 up to 1.5 times the short side length D3. Therefore, the reinforced concrete column 201 of the second embodiment uses an elliptical core bar 203 formed in an elliptical shape to match the cross section of a column with a rectangular cross section.

The reinforced concrete column 201 of the second embodiment is a column component made of concrete 204 with a rectangular cross section, as shown in FIG. 9. The reinforced concrete column 201 has a number of main column reinforcements 211 arranged along its outer periphery and extending in the axial direction (Z direction) of the column, and a number of outer periphery reinforcements 2 and elliptical core reinforcements 203 surrounding them.

Of the multiple column main bars 211, column main bar 211a is a reinforcing bar arranged at the corner of the reinforced concrete column 201, and column main bar 211b is a reinforcing bar arranged near the corner. Column main bar 211c is a reinforcing bar arranged inside the elliptical core bar 203 near the center of the four sides. Hereinafter, unless there is a particular need to distinguish between them, column main bars 211a to 211c may be collectively referred to as column main bars 211.

The reinforced concrete column 201 is provided with an outer circumferential reinforcement 202 and an elliptical core reinforcement 203 as shear reinforcing bars. The outer circumferential reinforcement 202 is a shear reinforcing reinforcement placed along the outer periphery of the reinforced concrete column 201 and formed to have a rectangular shape in plan view. Further, the elliptical core reinforcement 203 is a shear reinforcing reinforcement arranged to overlap the outer peripheral reinforcement 202 and formed to have an elliptical shape in plan view.

As shown in Fig. 9, the length L2 of the long side of the peripheral streaks 202 and the length R2 of the major axis of the elliptical core streaks 203 are the same. Also, the length L3 of the short side of the peripheral streaks 202 and the length R3 of the minor axis of the elliptical core streaks 203 are the same. As a result, the peripheral streaks 202 and the elliptical core streaks 203 are in contact with each other at four contact points 205.
More specifically, the elliptical core stud 203 is positioned so that the center of the long side and the center of the short side of the peripheral stud 202 contact both front-to-rear end portions and width-wise end portions of the elliptical core stud 203.

In addition, the elliptical core 203 is circumscribed relative to the peripheral reinforcement 202 as shown in FIG. 9, and as shown in FIG. 10 and FIG. 11, when viewed from the side, the elliptical core 203 is positioned above the peripheral reinforcement 202.

As with the reinforced concrete column 1 of the first embodiment, the periphery reinforcement 202 and the elliptical core reinforcement 203 are arc welded at the four contact points (contact points 205). The periphery reinforcement 202 and the elliptical core reinforcement 203 may be tied together at the contact points 205 using a tie wire. The periphery reinforcement 202 may be placed between two elliptical core reinforcements 203 placed above and below to form a set of shear reinforcement. The elliptical core reinforcement 203 may also be placed independently of the periphery reinforcement 202. In other words, the elliptical core reinforcement 203 does not have to be placed directly on top of the periphery reinforcement 202, and the elliptical core reinforcement 203 may be placed between the periphery reinforcements 202 placed above and below at a predetermined interval P.

The outer circumferential reinforcement 202 and the elliptical core reinforcement 203 are closed reinforcing bars, and by welding or bundling at the four contact points 205, one outer peripheral reinforcement 202 (square hoop) and one elliptical core reinforcement 203 are formed. (elliptical hoop) are arranged as an integral set. That is, each set is composed of a total of two shear reinforcing bars, and as shown in FIGS. Reinforced at height.

The rectangular outer circumferential reinforcing bars 202 are arranged so as to surround a plurality of column main reinforcing bars 211 arranged along the outer periphery of the reinforced concrete column 201, as shown in FIG. In addition, the elliptical core reinforcement 203 surrounds the column main reinforcement 211c arranged at the center of the side among the plurality of column main reinforcements 211, excluding the column main reinforcement 211a at the corner and the column main reinforcement 211b near the corner. It is arranged like this.

9, the column main reinforcement 211c is disposed closer to the inside of the reinforced concrete column 201 than the column main reinforcement 211a, 211b disposed at the corner and near the corner, so that when the elliptical core reinforcement 203 is disposed, the elliptical core reinforcement 203 does not interfere with the column main reinforcement 211c.
As in the reinforced concrete column 1 of the first embodiment, a high-strength reinforcing bar having a yield point of 590 to 1275 N/ ^mm2 , such as MK785, may be used for the peripheral reinforcing bars 202 or the elliptical core reinforcing bars 203. High-strength reinforcing bars may be used for both the peripheral reinforcing bars 202 and the elliptical core reinforcing bars 203.

The effect of the elliptical core bar 203 used in the reinforced concrete column 201 of the second embodiment is similar to that of the circular core bar 3 of the first embodiment, so its explanation will be omitted. However, to put it simply, by adopting the elliptical core bar 203 for the reinforced concrete column 201 having a rectangular cross-sectional shape, the concrete 204 inside the elliptical core bar 203 is tightened when a high axial force is applied.
That is, the elliptical core bar 203 resists the force applied to the concrete 204, which tends to expand due to high axial force, with the axial tensile stress of the elliptical core bar 203. The elliptical core bar 203 acts in the same way as the so-called "wrap of a wooden barrel."

By making the core muscle elliptical, one elliptical core muscle 203 (elliptical hoop) exhibits the effect of suppressing bulges in both the X and Y directions, similar to the circular core muscle. In the case of the conventional linear core reinforcement 103, in order to resist stress in the orthogonal direction, it was necessary to insert linear core reinforcements 103a and 103b arranged orthogonally to each other. Therefore, when comparing the lengths of the materials used as core reinforcements (lengths of reinforcing bars), the total length of elliptical core reinforcements 203 is shorter than that of linear core reinforcements 103a and 103b; The amount can be reduced by approximately 40%. Therefore, by forming the core reinforcement into an elliptical shape, costs can be reduced.
In other words, in the reinforced concrete column 1 of this embodiment shown in FIGS. 9 to 11, compared to the case where the conventional linear core reinforcement 103 shown in FIG. 8 is used, when the dimensions of the column are the same, the It is possible to obtain the same effect as shear reinforcing bars with a smaller amount of reinforcing bars.
Furthermore, there is no need for a reinforcing worker to arrange the linear core reinforcements 103 one by one as in the past, making construction easier and reducing the time required to assemble the columns.

1, 201 Reinforced concrete column 101 Square column member 2, 102 Peripheral reinforcement 3, 3a Circular core reinforcement (core reinforcement)
203 Elliptical streaks (streaks)
3b Second circular core (core)
103a, 103b Straight core bars 4, 204 Concrete 5, 205 Contact point 11, 211 Column main bars 11a, 211a Column main bars at corners 11b, 211b Column main bars near corners 11c, 211c Column main bars at center of sides

Claims (4)

A reinforced concrete column with a square cross section,
a rectangular peripheral reinforcement arranged along the outer periphery of the reinforced concrete column and surrounding a plurality of column main reinforcements;
a first core muscle arranged inside the outer circumferential muscle and formed in a circular shape;
a second core reinforcement formed in the same shape as the first core reinforcement;
The circular diameter of the first core reinforcement and the length of one side of the peripheral reinforcement are the same, and the first core reinforcement is arranged above the peripheral reinforcement and is different from the first core reinforcement. The above-mentioned peripheral muscles are in contact at four points ,
The reinforced concrete column is characterized in that the second core reinforcement is disposed below the peripheral reinforcement, and the second core reinforcement and the peripheral reinforcement are in contact with each other at four points . A reinforced concrete column with a square cross section,
a rectangular peripheral reinforcement arranged along the outer periphery of the reinforced concrete column and surrounding a plurality of column main reinforcements;
a first core muscle arranged inside the outer circumferential muscle and formed in a circular shape;
a second core reinforcement formed in the same shape as the first core reinforcement;
The circular diameter of the first core reinforcement and the length of one side of the peripheral reinforcement are the same, and the first core reinforcement and the peripheral reinforcement are in contact at four points ,
The outer circumferential reinforcing bars and the first core reinforcing bars are arranged in pairs on the axis of the reinforced concrete column, and in each set, the outer circumferential reinforcing bars and the first core reinforcing bars are integrally formed. It is arranged as follows.
A reinforced concrete column , wherein the second core reinforcing bars are arranged at a predetermined distance from the outer circumferential reinforcing bars between the adjacent sets . 3. A reinforced concrete column as claimed in claim 1 or 2, characterized in that the outer perimeter reinforcement and the first core reinforcement are welded or tied together at four points of contact. The outer reinforcing steel , the first core reinforcing steel, and the second core reinforcing steel are formed from high-strength reinforcing bars having a yield point of 590 to 1275 N/mm ^{2 .} A reinforced concrete column as described in any one of the above.