JP3622100B2 - How to reinforce existing beams - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of retrofitting an existing beam in a column beam joint portion of a reinforced concrete structure (hereinafter referred to as RC structure) or a steel-framed reinforced concrete structure (hereinafter referred to as SRC structure).
[0002]
[Prior art]
Conventionally, when further strengthening the horizontal strength of an existing building, or when reinforcing an existing beam when an existing beam of an existing building is damaged by an earthquake, It is necessary to increase the bending strength at the beam-column joint. As a general reinforcing method, as shown in FIG. 6, an additional beam main bar c is arranged on the lower surface of the existing beam b, and a post-installed anchor d such as a chemical anchor is arranged. Anchor d is embedded in the cross section of existing pillar a and fixed. On the other hand, an additional stirrup e is arranged on the outer periphery of the extension beam main reinforcement c and the existing beam b, an unillustrated formwork is assembled, and the increased concrete f is placed, thereby placing the existing beam b. We are reinforcing.
[0003]
JP-A-61-277732, JP-A-4-350228, and JP-A-7-48876 disclose an annular reinforcing plate attached to a new steel pipe column in order to increase the horizontal strength of the building. Has been.
[0004]
[Problems to be solved by the invention]
In the case of the conventional example shown in FIG. 6, since the post-construction anchor d is embedded in the existing column a, the existing column a may be damaged, and the dynamic performance of the column may be deteriorated. Moreover, many reinforcing bars (not shown) are densely arranged in the cross section of the existing column a, and the post-construction anchor d cannot be embedded well. In addition, there is a problem that the post-installed anchor d has poor durability.
[0005]
Further, the annular reinforcing plate described in JP-A-61-277732 and two other publications is a reinforcing material attached to a newly installed steel pipe column, and is not attached to an existing column by post-installation. In addition, since the columns to which these reinforcing plates are attached are all limited to steel pipe columns, they are not applicable to RC columns.
[0006]
Accordingly, an object of the present invention is to efficiently use the ring plate at the beam-column joint of the existing RC building or the like in order to enhance the horizontal strength of the existing RC structure or SRC structure. It also provides a method of reinforcing the existing beams after the maintenance while maintaining the soundness of the frame without damaging the existing columns.
[0007]
[Means for Solving the Problems]
As a means for solving the problems of the prior art, the reinforcing method of the existing beam according to the invention of claim 1 is a method of reinforcing the existing beam 2 in the column beam joint portion of the RC structure or the SRC structure, An annular ring plate 5 is arranged on the outer periphery of the existing pillar 1 at the level position of the lower surface 2a of the existing beam 2, and the outer peripheral end 5a of the ring plate 5 protrudes horizontally from the ring plate in the direction of the existing beam. The extension plate 6 is provided, the filler 3 is filled in the gap 3 between the inner peripheral end 5b of the ring plate 5 and the existing pillar 1, and the extension plate 6 is installed with the post-installed anchor 7 or the adhesive. It is characterized by being tightly reinforced to the lower surface 2a of the beam 2.
[0008]
The reinforcing method of the existing beam according to the invention described in claim 2 is that after the annular ring plate 5 is disposed on the outer periphery of the existing column 1 at the level position of the lower surface 2a of the existing beam 2, the inner periphery of the ring plate 5 is Filling the gap 3 between the end 5b and the existing pillar 1 with the filler 4, and arranging the extension beam main reinforcement 8 on the lower surface 2a of the existing beam 2, and the end of the extension beam reinforcement 8 is After joining the outer peripheral end 5a of the ring plate 5 and arranging the additional stirrup 9 on the outer periphery of the extension beam main reinforcement 8 and the existing beam 2, the formwork is assembled, and the extension beam main reinforcement 8 and It is characterized in that reinforcing concrete 10 is placed on the stirrup 9 for reinforcement.
[0009]
The inventions of 請 Motomeko 3, wherein in the reinforcing method of existing beam according to claim 1 or 2,
A vertical plate 12 formed in an angle shape or the like is provided in the gap 3 between the ring plate 5 and the existing pillar 1 in the vertical direction along the outer periphery of the existing pillar 1.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The method of reinforcing an existing beam according to the invention of claim 1 is to increase the horizontal strength of the existing beam 2 in the RC building or SRC building, or to increase the horizontal strength of the existing beam 2 damaged by an earthquake or the like. In the case of recovery, it is preferably carried out when the existing beam 2 is retrofitted later using the ring plate 5 and the extension plate 6, the reinforcing bars 8 and 9, etc. at the column beam joint. However, when the beam span is short (not shown), a reinforcing material such as the extended plate 6 is used over the entire length of the existing beam 2.
[0011]
A basic embodiment of the ring plate 5 is shown in FIGS. Any of the ring plates 5 is formed in an annular body by a steel plate. 2A and 2B show an example of a ring plate 5 having an outer shape formed in a circular shape, and FIGS. 3A and 3B show an example of a ring plate 5 ′ having an outer shape formed in a substantially square shape (exactly an octagon). Each central portion is formed in a through hole 5 c having a shape that matches the cross-sectional shape of the existing pillar 1. 2A and 3A are examples of a through-hole portion 5c formed in a square shape when the existing column 1 is a prismatic column, and FIGS. 2B and 3B are a through-hole portion formed in a circular shape when the existing column 1 is a cylinder. An example of 5c is shown. The size of the through hole 5c is set to be slightly larger than the cross-sectional area of the existing pillar 1. For example, in the case of the square-shaped through hole portion 5c shown in FIG. 2A (or FIG. 3A), as shown in FIG. 1B, the outer periphery of the square existing pillar 1 inserted inside and the center through-hole portion 5c. The gap 3 is formed in such a size that it can be formed between it and the peripheral end 5b. An extended plate 6 protruding horizontally from the ring plate 5 in the direction of the existing beams 2 is joined to the outer peripheral end 5a of the ring plate 5 by welding. 2 and 3 show an example in which the four extension plates 6 are arranged in a cross shape, but the number and arrangement are not limited thereto. The ring plate 5 is usually divided into two halves (not shown).
[0012]
Below, the reinforcement method of the existing beam which uses the said ring plate 5 is demonstrated. The ring plate 5 having the halved shape is wound around the outer periphery of the existing pillar 1 on the work floor and integrally fixed by welding. Further, a desired extending plate 6 is welded and joined to the outer peripheral end 5 a of the ring plate 5. Thereafter, the ring plate 5 having the extension plate 6 is lifted and moved to the lower surface of the existing beam 2 at the column beam joint. That is, as shown in FIG. 1A, the ring plate 5 is disposed with the gap 3 provided on the outer periphery of the existing column 1 at the lower surface level position of the existing beam 2, and then, as shown in FIG. 3 is filled with a filler 4. As the filler 4, non-shrinkable high-strength mortar, epoxy resin, or the like that is not fluid is suitable. And in the state which fixed this ring plate 5 to the existing pillar 1, the extension plate 6 embeds the post-construction anchor 7 in the direction of the existing beam 2 from below, or adhesion | attachment of the epoxy resin etc. which abbreviate | omitted illustration Tighten to the lower surface 2a of the existing beam 2 using an agent. Accordingly, the ring plate 5 bears a part of the bending moment in the direction in which the tensile force acts on the lower surface 2a of the existing beam 2, and the bending strength can be increased. Further, the increase or decrease of the required bending strength can be adjusted by the size and thickness of the ring plate 5.
[0013]
In addition, the ring plate 5 is moved to the lower surface of the existing beam 2 and the filler 3 is filled in the gap 3 without previously performing the joining operation of the extending plate 6 to the ring plate 5 in a factory or work floor shape. It may be done later.
Next, a method for reinforcing an existing beam according to the invention described in claim 2 will be described. This reinforcing method is also carried out to reinforce the existing beam 2 later using the ring plate 5 at the column beam joint in the RC building or SRC building, as in the first aspect of the invention. . However, it differs from the invention of claim 1 in that instead of the extension plate 6, an additional beam main reinforcement 8, stirrup 9, and additional concrete 10 are used (FIG. 4).
[0014]
That is, as in the first aspect of the present invention, first, after the gap 3 is provided on the outer periphery of the existing column 1 at the lower surface level position of the existing beam 2 and the annular ring plate 5 is disposed, the filler is put into the gap 3. 4 is filled. Then, as shown in FIGS. 4A and 4B, an extension beam main reinforcement 8 is arranged on the lower surface 2a of the existing beam 2, and the end of the extension beam reinforcement 8 is connected to the outer peripheral end 5a of the ring plate 5. Join by welding. After the extension stirrup 9 is arranged on the outer periphery of the extension beam main reinforcement 8 and the existing beam 2, the formwork is assembled, and the additional concrete 10 is applied to the extension beam main reinforcement 8 and the stirrup 9 portion. The existing beam 2 can be efficiently reinforced by installing and removing the mold.
[0016]
Further, when the planar shape is square and formed as small as possible as in the ring plate 5 ′ shown in FIG. 5B (FIG. 3A), local destruction may occur in the existing pillar 1 with the support pressure of the plate. There is. In such a case, as shown in FIGS. 5A and 5B, the vertical plate 12 formed in an angle shape is inserted into the gap 3 between the inner peripheral end 5 b of the ring plate 5 and the existing square pillar 1. By providing the four vertical corners of the existing pillar 1 in the vertical direction, local destruction can be prevented (claim 3 ). In addition, the shape of the vertical plate 12 is not limited to the angle shape in the illustrated example, and can be applied to the outer periphery of the circular existing pillar 1 by being formed in a curved shape or the like. Further, the embodiment in which the vertical plate 12 can be used is not limited to the type using the extended plate 6 shown in FIG. 5 (see claim 1), but is a concrete-strike type (not shown). It is also applicable to
[0017]
[Effects of the invention]
According to the method of reinforcing an existing beam by a type using an extension plate in the ring plate of the invention of claim 1 and an additional type of concrete using the ring plate of the invention of claim 2, an existing RC building or the like At the beam-to-column joint, the bending strength of the existing beam ends will be increased later to increase the horizontal strength of the existing building, and the seismic reinforcement will be achieved efficiently. Moreover, since it is a form which does not embed any post-construction anchor in the existing pillar, the soundness of a housing is also maintained permanently without damaging the existing pillar.
[Brief description of the drawings]
FIGS. 1A and 1B are a longitudinal sectional view and a bottom view showing a reinforcing state of an existing beam by a ring plate having an extending plate, respectively.
FIGS. 2A and 2B are plan views of a ring plate having an extending plate. FIGS.
FIGS. 3A and 3B are plan views of different ring plates. FIGS.
4A and 4B are cross-sectional views of an embodiment using a ring plate.
FIGS. 5A and 5B are a longitudinal sectional view and a transverse sectional view showing how to implement a vertical plate, respectively.
FIG. 6 is a cross-sectional view showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Existing pillar 2 Existing beam 3 Gap 4 Filler 5 Ring plate 6 Extension plate 7 Anchor 8 Beam main reinforcement 9 Expansion stirrup 10 Additional concrete
1 2 Vertical plate

Claims (3)

A method of reinforcing an existing beam in a column beam joint of a reinforced concrete structure or a steel reinforced concrete structure,
An annular ring plate is disposed on the outer periphery of the existing column at the lower surface level position of the existing beam, and an extending plate that protrudes horizontally from the ring plate in the direction of the existing beam is provided at the outer peripheral end of the ring plate,
Filling the gap between the inner peripheral edge of the ring plate and the existing pillar with a filler,
A method for reinforcing an existing beam, characterized in that a post-installed anchor or an adhesive is used to tie and extend an extended plate to the lower surface of the existing beam. A method of reinforcing an existing beam in a column beam joint of a reinforced concrete structure or a steel reinforced concrete structure,
After disposing an annular ring plate on the outer periphery of the existing column at the lower surface level position of the existing beam, filling a gap between the inner peripheral end of the ring plate and the existing column with a filler,
And then Haisuji beams main reinforcement for added to the lower surface of the existing beam, joining the end of the add-beam main reinforcement of this outer peripheral end portion of the ring plate,
After the expansion beam stirrup and the stirrup for expansion are arranged on the outer circumference of the existing beam, the formwork is assembled, and the additional beam concrete is placed on the expansion beam main reinforcement and stirrup part to reinforce. A method of reinforcing an existing beam, characterized by: The method of reinforcing an existing beam according to claim 1 or 2, wherein a vertical plate formed in an angle shape or the like is provided in a gap between the ring plate and the existing column in a vertical direction along the outer periphery of the existing column. .

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