JPH0941676A - Shear strength improvement type existing RC column reinforcement method - Google Patents

Abstract

(57) An object of the present invention is to improve the bending rigidity at the center of an existing RC column, while improving the shear strength at the ends of the column, that is, near the upper slab and the lower slab. (EN) Provided is a shear strength improving type existing RC column reinforcing method capable of improving earthquake resistance with high efficiency. SOLUTION: The center part of the existing RC column 9 fixed between the upper slab 10 and the lower slab 11 is provided with a new reinforcing RC body 1.
And the upper and lower ends near the upper floor slab 10 and the lower floor slab 11 are surrounded by the reinforcing strip steel plate 2 for reinforcement. Due to the above, shortening of the column can be prevented, and shear strength can be improved. Further, by enclosing the outer circumference of the reinforcing strip steel plate 2 with ordinary concrete 8, it is possible to improve the fire resistance and the overall rigidity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to strength reinforcement of reinforced concrete columns according to the old design standard, and more particularly to a shear strength improving type existing RC column reinforcement method suitable for reinforcing shear strength.

[0002]

2. Description of the Related Art An existing concrete structure (hereinafter referred to as RC structure) was considerably damaged by the Tokachi-oki Earthquake of 1968. Since then, as a result of re-examination of seismic design of RC structures and re-examination of seismic resistance of existing RC buildings, it has been found that the force assumed in the design may be several times higher. It was Therefore, the Architectural Institute of Japan revised the RC structural calculation criteria in 1969. Since some existing reinforced concrete columns (called existing RC columns) do not satisfy this revised standard, reinforcement of existing RC columns is obligatory, and various reinforcement methods or structures have been adopted.

4 and 5 show a general outline structure of a conventional RC column 9 in the past. The RC pillar 9 is composed of a concrete pillar 13 which is fixedly arranged between the upper slab 10 and the lower slab 11 and surrounded by a reinforcing bar 12. The outer circumference of the reinforcing bar 12 is covered with concrete 14 to provide fire resistance.
The reinforcing bar 12 is reinforced by a band bar 15 wound around the reinforcing bar 12. In the above structure, the RC column 9 receives bending stress, and a large shearing force acts particularly on the portions near the upper slab 10 and the lower slab 11.

FIG. 6 shows one of the prior art of the reinforcing structure. This reinforced structure consists of surrounding the existing RC columns 9 with new RC columns 16.

7 and 8 show another conventional reinforcing structure. The outer circumference of the existing RC column 9 is surrounded by the reinforcing iron plate 18 via the grout mortar 17. The reinforcing iron plate 18 is arranged over almost the entire range of the column length of the existing RC column 9. The reinforcing iron plate 18 is surrounded by finishing lath mortar 19 and is fireproof coated.

In FIGS. 9 and 10, the L-shaped steel 20 is applied to the corners of the existing RC column 9, and the L-shaped steels 20 and 20 are joined together to form a strip steel 21.
Are connected by The L-shaped steel 20 and the strip steel 21 are erected over substantially the entire column length. Also, these are fireproof coated with mortar 22.

[0007]

Each of the above-mentioned prior arts has a reinforcing function, but has the following problems. That is, in the case of a RC column having a double structure, the bending rigidity increases, but the ratio in the thickness direction to the column length becomes large, resulting in a short column structure, the deformability decreases, and the seismic strength partially decreases. There is a point. In addition, the reinforcing iron plate 18 and the L-shaped steel 20
In addition, the one containing the steel strip 21 has a problem that the toughness is improved, but the structure becomes heavy and the cost becomes high, and the fireproof coating is required, and the equipment cost and the construction cost become large.

The present invention solves the above-mentioned problems, and it is possible to improve the seismic resistance, the shear strength at both ends is high, and the weight increase is relatively small. The purpose is to provide a reinforcing method.

[0009]

In order to achieve the above-mentioned object, the present invention is a reinforced concrete column reinforcement structure having upper and lower ends fixed, wherein a portion separated from the upper and lower ends by an appropriate interval and the interval. The present invention is characterized by a shear strength improving type existing RC column reinforcing method in which reinforcing members formed by different types of reinforcing methods are arranged inside and inside, and the outer periphery of an existing reinforced concrete column is reinforced. Further, more specifically, a reinforcing reinforced concrete body surrounding an existing reinforced concrete column is fixedly attached to a portion distant from the upper and lower ends by an appropriate interval, and the existing reinforced concrete column is wound within the interval, A reinforcing strip steel plate to be tightened and fixed to is disposed, and is surrounded by concrete, wherein the outer surface of the concrete is formed substantially flush with the outer surface of the reinforcing concrete. To do.

The upper and lower ends of the existing RC column except for a predetermined interval are surrounded by the RC column to form a double RC column. On the other hand, the existing RC column is wound and secured by band steel at the above-mentioned interval. Due to the above reinforcement structure, the bending strength of the middle part of the column is large and the seismic strength is improved. On the other hand, since the vicinity of the upper and lower ends where a large shearing force acts is reinforced by the strip steel,
The shear rigidity is improved, and the strength is sufficient to withstand the shearing force applied to the upper and lower ends. On the other hand, the bending strength can be improved by surrounding the portion wound with the strip steel with ordinary concrete.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for reinforcing an existing RC column according to the present invention will be described in detail with reference to the drawings.
1 is a front view thereof, and FIGS. 2 and 3 are A- of FIG.
It is the sectional view on the A line and the sectional view on the BB line. The reinforcing structure of the present invention surrounds the middle part of the existing RC column 9 to form a double RC column.
1) and a reinforcing strip steel plate 2 provided at the upper and lower ends.

As described above, the existing RC pillar 9 fixedly arranged between the upper slab 10 and the lower slab 11 is
It consists of concrete columns 13 surrounded by reinforcing bars 12. The outer periphery of the reinforcing bar 12 is covered with a mortar 14 to maintain fire resistance. In addition, the reinforcing bar 12 is wound around the reinforcing bar 12,
To reinforce.

A reinforcing RC body 1 is formed apart from the upper slab 10 and the lower slab 11 by a predetermined distance. The reinforcing RC body 1 is composed of a concrete portion 3 surrounding the existing RC column 9, rebars 4 arranged at the corners and the like, a mortar 5 surrounding the rebar 4, and the like. It should be noted that the reinforcing bar 4 has a stirrup 6
Is wound and fixed. As described above, the middle portion of the existing RC column 9 is surrounded and reinforced by the reinforcing RC body 1.

The reinforcing strip steel plate 2 is provided in the existing RC within the space.
It is arranged so as to surround the pillar 9. As shown in FIG. 1 and FIG. 3, the reinforcing strip steel plate 2 is made of a pair of iron plates having an appropriate thickness having a width dimension corresponding to the spacing, is arranged in contact with the outer circumference of the existing RC column 9, and is an intermediate portion which is integrated with each other. In, the bolt 7 and the plate member 23 are installed and welded and fixed to each other.

As described above, according to the reinforcing structure of the present invention, the portions adjacent to the upper slab 10 and the lower slab 11 are reinforced by the reinforcing strip steel plate 2 and the outer circumference of the existing RC column 9 at a place other than the above-mentioned intervals. Is surrounded by a reinforcing RC body 1 for reinforcement. With the structure described above, the existing RC column 9 can improve the bending rigidity of the middle portion thereof, and can also improve the shear strength in the portions close to the upper slab 10 and the lower slab 11. Therefore, it is possible to sufficiently withstand the shearing force acting on the column and prevent shear failure.

As shown in FIG. 1, ordinary concrete 8 is provided around the reinforcing strip steel plate 2 so as to surround the reinforcing strip steel plate 2. As a result, the reinforcing strip steel plate 2 can be protected and the overall rigidity of that portion can be further improved.

Although the structure of the existing RC column 9 is shown in the above description, this is an example, and another shape and model may be used. In addition, reinforcing bars 4, 12 and stirrup bars 6, 15
Also, the shape, arrangement, number, etc. are not limited to those illustrated.

[0018]

According to the present invention, the following remarkable effects are obtained. 1) In the reinforcing structure of the present invention, since the middle portion of the existing RC column is surrounded by the RC column to form a double RC column, the bending rigidity is improved, and the upper and lower ends are reinforced by the strip steel plate, In particular, the shear strength can be improved. 2) Since the entire structure is not double reinforced with concrete, the short columns are prevented and the changeability is not reduced. 3) Since the place where the steel plate is used is limited to the upper and lower specific parts, the fireproof coating of the steel material is hardly required unlike the prior art. 4) It is possible to change the plate shape of the reinforcing strip steel plate according to the application place, which increases the degree of freedom in setting shear strength.

[Brief description of drawings]

FIG. 1 is a front view showing an overall structure of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a front view of a conventional RC column.

5 is a sectional view taken along line CC of FIG.

FIG. 6 is a front view showing a schematic structure of a conventional double RC column.

FIG. 7 is a front view showing a conventional iron plate type reinforcing structure.

FIG. 8 is a sectional view taken along line DD of FIG. 7;

FIG. 9 is a front view showing a conventional reinforcing structure using an L-shaped steel and a strip steel.

FIG. 10 is a sectional view taken along line EE of FIG. 9;

[Explanation of symbols]

 1 Reinforced Reinforced Concrete Body (Reinforced RC Body) 2 Reinforcement Strip Steel Plate 3 Concrete Part 4 Reinforcing Bar 5 Mortar 6 Belt Reinforcement 7 Bolt 8 Normal Concrete 9 Existing Reinforced Concrete Column (Existing RC Column) 10 Upper Floor Slab 11 Lower Floor Slab 12 Reinforcing Bar 13 Concrete columns 14 Concrete 15 Strips

Claims (3)

[Claims] 1. A reinforcing structure for a reinforced concrete column having upper and lower ends fixed, wherein reinforcing members formed by different kinds of reinforcing methods are arranged in a portion separated from the upper and lower ends by an appropriate interval and in the interval. An existing RC column reinforcing method for improving shear strength, which is characterized in that the outer periphery of an existing reinforced concrete column is reinforced. 2. A reinforcing reinforced concrete body surrounding an existing reinforced concrete column is fixed to a portion distant from the upper and lower ends by an appropriate interval, and the existing reinforced concrete column is wound within the interval and tightened to the concrete column. The method for reinforcing existing RC columns according to claim 1, wherein a reinforcing strip steel plate to be fixed is provided. 3. The shear strength improvement of claim 1, wherein the reinforcing strip steel plate is surrounded by concrete, and the outer surface of the concrete is substantially flush with the outer surface of the reinforcing concrete. Type existing RC column reinforcement method.