JPH1025909A - Reinforcing structure of existing building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sufficient earthquake resistance by a method wherein a carbon fibre reinforcing material is wound around the upper and lower end parts of a column to repair the named parts, an after-placed reinforced concrete-made wall is integrally built through a beam and an anchor beam between the column and the beam, and the column is built without being integrally built. SOLUTION: A carbon fibre reinforcing material 13 is wound around the upper and lower end parts of a PC-made column 10 to effect reinforcement and an after- placed RC-made wall 12 is integrally built through a beam 11 and an anchor bar 14 but built without being built integrally with the column 10. Since the wall 12 is not built integrally with the column 10, a transmission content of a shearing force by the truss effect of a frame comprising the column 10 and the beam 11 is decreased. Transmission of a shearing force by an arch effect is main and though a shearing force from an arch is locally increased at the upper and lower end parts of the column 10, since the upper and lower end parts are increased in rigidity through winding of the upper and lower end parts with a reinforcing material 13, a high out-of-plane stress is exerted on the column 10 due to an earthquake force, shear fracture is effectively suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing structure for an existing building, which is suitable for use in performing seismic retrofitting of various existing concrete buildings.

[0002]

2. Description of the Related Art Conventionally, reinforced concrete (hereinafter referred to as R
Abbreviated as C. ) Construction and steel reinforced concrete (hereinafter, SRC
Abbreviated. ) When seismic retrofitting is performed on an existing concrete building such as a structure, usually, as shown in FIG.
A construction method of constructing an earthquake-resistant wall 3 made of post-cast concrete between a column 1 and a beam 2 is adopted. At this time, the columns 1 and the beams 2 of the earthquake-resistant wall 3 are provided in order to increase the rigidity of the structure where the earthquake-resistant wall 3 is added and to secure the earthquake resistance.
Anchor bars 4 are buried in the four circumferences facing each other, so that the earthquake-resistant wall 3 is integrated with the existing frame including the columns 1 and the beams 2.

[0003]

On the other hand, due to the recent increase in awareness of earthquake resistance, this type of RC construction and SR
There is a growing demand for existing buildings such as C-structures to be reinforced in anticipation of the occurrence of a larger earthquake than before. However, when the conventional RC structure shown in FIG. 3 is applied to the seismic reinforcement for such a large earthquake, when the large earthquake occurs, the frame is greatly deformed and shears to the shear wall 3. Cracks may occur, and as a result, an excessive tensile force and shear force may act on the anchor streaks 4 and come off. And especially Pillar 1
When the anchor bar 4 provided on the side surface of the slab comes off, as shown in FIG. 4, the surrounding concrete 1a is also cut off in a cone shape. As a result, the column 1 has a cross-sectional defect, and its axial proof stress is remarkably reduced. As a result, not only the desired earthquake resistance due to the original earthquake-resistant wall 3 cannot be exhibited, but also the column 1 may be sheared and the vertical load holding capacity may be lost.

In order to prevent the anchor bar 4 from slipping out, it is conceivable that the anchor bar 4 has a sufficient anchoring length. However, the anchor bar 4 is fixed to the existing RC column 1. Drilling a correspondingly deep hole is extremely difficult and impractical in construction. Also, in general, existing RC buildings are premised on that each member such as RC columns 1 is elastic even during an earthquake, and is designed to be earthquake-resistant mainly based on strength against in-plane stress. On the other hand, in the case of an assumed large earthquake, the seismic force does not always act only in the extending direction of each member, and the out-of-plane stress in the direction perpendicular to the extending direction of each member such as the column 1 is not limited. Must also be considered so as not to cause shear failure. Therefore, from this viewpoint, in the existing RC buildings, there are few that can be said to have sufficient shear reinforcement bars such as columns.
Even when a large out-of-plane stress acts on the column 1, the column 1 may be sheared and may lose the above-described vertical load holding ability.

The present invention has been made in order to effectively solve the problems of the above-mentioned conventional existing building reinforcement structure, and can be sufficiently applied to an existing concrete building which is expected to have insufficient strength against a large earthquake. It is an object of the present invention to provide a reinforcement structure for an existing building that can provide excellent seismic resistance and is easy to construct.

[0006]

According to a first aspect of the present invention, there is provided a reinforcing structure for an existing building, wherein a carbon fiber reinforcing material is wound around at least upper and lower ends of RC columns of the existing building. And a post-rack between the column and the beam
It is characterized in that the C-shaped wall is constructed integrally with the beam via an anchor bar and without being integrated with the column. Here, the invention according to claim 2 is characterized in that a steel plate member is provided in place of the carbon fiber reinforcing material to reinforce the portion of the column, and the invention according to claim 3 is provided. The present invention is characterized in that a tension material is inserted into at least the upper and lower portions of the post-cast RC wall according to claim 1 or 2 and the column to introduce prestress.

In the invention according to any one of claims 1 to 3, a post-cast RC wall is provided between the RC column and the beam.
Since the beam and the beam are integrated via anchor bars and are not integrated with the column, even if the frame consisting of the column and beam is greatly deformed due to a large earthquake, There is no danger that the anchor streak provided on the side surface of the column will slip out and cause a cross-sectional defect in the column. In addition, at the time of construction, since it is not necessary to bury the anchor bar on the pillar side, the reinforcement work becomes extremely easy. By the way, as described above, in ordinary existing concrete buildings, the amount of shear reinforcement is not sufficient for a large earthquake as originally assumed, If the RC wall is not integrated with the column, the column may be insufficiently proof and shear fracture may occur.

In this respect, in the present invention, the rigidity is enhanced by winding a carbon fiber reinforcing material having excellent reinforcing strength on at least the upper and lower ends of columns of an existing building which is locally subjected to a large shear force during a large earthquake. Thus, since shear reinforcement is performed at the portion, even when a large out-of-plane stress is applied to the column due to seismic force, it is possible to effectively prevent the column from being sheared and fractured. From such a viewpoint, it is desirable that the range around which the carbon fiber reinforcing material is wound is at least 1.5 times or more the diameter of the pillar. Further, in particular, as in the invention according to claim 2, a steel plate member may be provided instead of the carbon fiber reinforcing material to reinforce the portion, and furthermore, as in the invention according to claim 3, If a prestress is introduced by inserting a tension material into at least the upper and lower portions of the post-cast RC wall and the upper and lower portions of the post, the top and bottom of the RC post, as well as the column head and column base of the post, are introduced. The rigidity of the portion can be greatly increased, which is more preferable.

[0009]

FIG. 1 shows an embodiment of a reinforcing structure for an existing building according to the present invention.
Are RC columns and beams in an existing RC laminated structure building. And this pillar 10 and beam 11
Seismic reinforcement is applied to predetermined positions of the frame made of. This aseismic reinforcement is performed by arranging an earthquake-resistant wall (wall of a post-cast RC structure) 12 constructed by placing cast concrete in the frame, and carbon fibers wound around upper and lower ends of the column 10, respectively. It is roughly constituted by the reinforcing member 13. Here, the earthquake-resistant wall 12 is integrated with the beam 11 by embedding a large number of anchor bars 14... Between the beam 11 when the post-cast concrete is cast. Between the earthquake-resistant wall 12 and the pillar 10,
It has a non-integrated structure with no anchor muscle interposed.
The carbon fiber reinforcing material 13 wound around the upper and lower ends of the column 10 has a length of 1.5 times or more of the column 10 from the upper or lower end of the column 10 toward the center. It is wound over. Further, a tension member 15 made of a PC steel wire or a PC steel rod is provided at the upper and lower ends of the above-mentioned earthquake-resistant wall 12 and the upper and lower ends of the column 10 around which the carbon fiber reinforcing material 13 is wound.
Is inserted and prestress is introduced.

According to the reinforcing structure of an existing building having the above-described structure, a post-cast RC-made earthquake-resistant wall 12 is integrated between the column 10 and the beam 11, and the beam 11 is integrated with the above-mentioned beam 11 via the anchor bars 14. 3 and 4 are constructed without being integrated with the column 10, so that even if a large earthquake occurs and the frame formed of the column 10 and the beam 11 is greatly deformed, the conventional structure shown in FIGS. Unlike the reinforcing structure of the above, there is no possibility that the anchor streak provided on the side surface of the column will slip out and cause a cross-sectional defect in the column. In addition, at the time of construction, there is no need to bury anchor bars on the side of the pillar 10, so that the reinforcement work becomes extremely easy.

Here, in the above-mentioned reinforcing structure, the side opposite to the column 10 of the earthquake-resistant wall 12 is not integrated with the column 10, so that the shear force due to the truss effect between the frame composed of the column 10 and the beam 11. , And the transmission of shear force mainly by the arch effect is mainly performed. As a result, pillar 10
Although the shearing force from the arch locally increases at the upper and lower ends, the carbon fiber reinforcing material 13 having excellent reinforcing strength is wound around the upper and lower ends to increase the rigidity.
For example, even when a large out-of-plane stress is applied to the column 10 due to seismic force, it is possible to effectively prevent the column 10 from shearing and breaking. In addition, the tension members 1 are attached to the upper and lower portions of the post-cast RC frame 12 and the upper and lower portions of the column 10.
5, the prestress is introduced, so that not only the upper and lower ends of the column 10 but also the rigidity of the upper and lower portions of the earthquake-resistant wall 12 can be greatly increased.

As a result, as shown in FIG. 5, the curve (b) of the conventional reinforced structure shown in FIG. 3 is compared with the curve (a) of the existing building without the reinforced structure. Although the rigidity of the frame is increased by the addition of the earthquake-resistant wall 3, the range of the elastic region that is linear is widened, but the amount of deformation up to shearing is reduced, but according to the present embodiment shown in FIG. In the reinforcement structure of the above-mentioned existing building, as shown in the load-deformation curve (c), the range of the elastic region that is linear is further expanded,
The load and deformability from plastic deformation to fracture also increase,
Therefore, existing RC, which is expected to have a shortage of capacity against a large earthquake
Sufficient seismic resistance can be imparted even to a built building.

In the above embodiment, the pillar 10
Although only the case where the carbon fiber reinforcing material 13 is wound around the upper and lower end portions has been described, the present invention is not limited to this. Instead of the carbon fiber reinforcing material 13 as in the other embodiment shown in FIG. A flat steel plate (steel plate member) 16 filled with a mortar 18 may be provided at least on the outer periphery of the upper and lower ends of the pillar 10 to reinforce the portion. Further, the present invention relates to R
It can be applied to the seismic retrofit of various concrete-based existing buildings such as C-building and SRC-building. At this time, depending on the degree of rigidity shortage of the existing RC columns, not only the upper and lower ends of the columns but also the entire length A carbon fiber reinforcing material or a steel plate member may be wound or provided.

[0014]

As described above, according to any one of the first to third aspects of the present invention, even when a large earthquake occurs and the frame including the columns and the beams is greatly deformed, the columns are not sheared. Destruction can be effectively suppressed, so that existing concrete buildings that are expected to have insufficient strength against large earthquakes can be provided with sufficient earthquake resistance, and reinforcement work is extremely easy become. here,
As the reinforcement of the column, a steel plate member may be provided instead of the carbon fiber reinforcing material as in the invention according to claim 2,
Further, as in the invention as set forth in claim 3, if a prestress is introduced by inserting a tension material into at least the upper and lower portions of the post-cast RC wall and the upper and lower portions of the column, the column capital and the column base of the column are provided. In addition, the rigidity of the upper and lower portions of the RC wall can be significantly increased.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a reinforcement structure for an existing building of the present invention.

FIG. 2 is a sectional view of the upper and lower ends of a pillar showing another embodiment of the present invention.

FIG. 3 is a front view showing a conventional existing building reinforcing structure.

4 is a longitudinal sectional view of a main part of the reinforcement structure of FIG. 3 showing a state in which anchor bars come off when a large earthquake occurs.

FIG. 5 is a load-deformation curve showing the effect of the reinforcing structure of FIG.

[Explanation of symbols]

 Reference Signs List 10 RC column 11 RC beam 12 Earthquake-resistant wall (post-cast RC wall) 13 Carbon fiber reinforcement 14 Anchor bar 16 Flat steel plate (steel plate member)

Claims (3)

[Claims] 1. A reinforcing structure for an existing concrete building, wherein a carbon fiber reinforcing material is wound around at least upper and lower ends of columns of the building to reinforce the portion, and the column and the beam are connected to each other. A reinforcing structure for an existing building, wherein a post-reinforced reinforced concrete wall is interposed between the beam and the anchor bar, and is not integrated with the pillar. 2. At least at the upper and lower ends of the pillars of the building,
The reinforcing structure for an existing building according to claim 1, wherein a steel plate member is provided instead of the carbon fiber reinforcing material to reinforce the portion. 3. The reinforcing structure for an existing building according to claim 1, wherein a tension member is inserted into at least the upper and lower portions of the post-cast reinforced concrete wall and the column to introduce prestress. .