JP3772247B2 - Seismic reinforcement method for bending of existing large beams - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of seismic reinforcement for a bending of an existing large beam in a column beam joint of a reinforced concrete structure (hereinafter referred to as RC structure) or a steel reinforced concrete structure (hereinafter referred to as SRC structure). The present invention relates to a seismic reinforcement method for bending existing large beams that belongs to the technical field and is further devised so as to be dry and have as few on-site construction steps as possible.
[0002]
[Prior art]
Conventionally, in order to reinforce the existing large beam when the horizontal strength of the existing building is further increased, or when the existing large beam of the existing building is damaged by the earthquake, That is, it is necessary to increase the bending strength at the column beam joint. As a general reinforcement method, as shown in FIG. 9, an additional beam main bar c is arranged on the lower surface of the existing large beam b, and a post-installed anchor d such as a chemical anchor is placed in the cross section of the existing column a. Embed in and settle. On the other hand, an additional stirrup e is arranged on the outer periphery of the main beam c for expansion and the existing large beam b, a formwork not shown in the figure is assembled, and the increased concrete f is placed, thereby constructing the existing large beam b. Reinforcement is performed.
[0003]
[Problems to be solved by the present invention]
In the case of the conventional example shown in FIG. 9, since the post-installed anchor d is embedded in the cross section of 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. Further, since the work of placing the increased-strength concrete f is indispensable, it is difficult to say that the efficiency is economically and in terms of construction period, and it has been hardly carried out. In addition, there is a problem that the post-installed anchor d has poor durability.
[0004]
Accordingly, an object of the present invention is to efficiently use existing reinforcing plates or the like at the column beam joints of existing RC buildings in order to reinforce the horizontal strength of existing RC structures or SRC structures. The method of increasing the bending strength of the girder is to provide a method for reinforcing the existing girder reasonably and effectively afterwards while maintaining the soundness of the frame without damaging the existing columns.
[0005]
A further object of the present invention is an existing large beam that is excellent in terms of usability and design of the building after reinforcement, is dry, and can be carried out with as few on-site construction processes as possible, economically and in terms of construction period. It is to provide a method of seismic reinforcement against bending of steel.
[0006]
[Means for Solving the Problems]
As a means for solving the problems of the prior art, the seismic reinforcement method for bending of an existing large beam according to the invention of claim 1 is for bending of an existing large beam in a column beam joint of a reinforced concrete structure or a steel reinforced concrete structure. A method of seismic reinforcement,
Attaching a plate-shaped upper outer diaphragm 7 divided into a plurality of shapes in a shape that surrounds the existing pillar 1 on the upper surface of the floor slab 11 and that follows the planar shape of the existing large beam 2;
A column cover plate 8 having a notch 8 ′ corresponding to the cross-sectional shape of the existing large beam 2 on the outer periphery of the existing column 1 in the column beam joint on the lower surface side of the floor slab 11 is divided into a plurality of columns. Attaching process;
A step of attaching a beam reinforcing plate 9 having an inverted L-shaped cross section to the side surface of the existing large beam 2, comprising a flange 9 a that contacts the lower surface of the floor slab 11 and a web 9 b that contacts the side surface of the existing large beam 2;
A plate-like lower outer diaphragm 10 is attached to the outer periphery of the existing column 1 at the lower surface level position of the existing beam 2 so as to surround the column cover plate 8 and follow the planar shape of the existing beam 2 and divided into a plurality of flat plates. Process,
A step of integrally joining the contact portions of the column cover plate 8, the beam reinforcing plate 9, and the lower outer diaphragm 10, respectively;
The step of crimping the flange portion 9a of the beam reinforcing plate 9 closely attached to the lower surface of the floor slab 11 and the upper outer diaphragm 7 with a plurality of bolts 12 penetrating the floor slab 11 and nuts 13 screwed into the bolts. When,
And a step of crimping the web 9b of the beam reinforcing plate 9 to the side surface of the existing large beam 2 by a plurality of anchors 14 driven into the existing large beam 2 .
[0008]
Earthquake-proof reinforcement method for existing girders bending according to the invention of claim 2, the beam reinforcement plate 9 and the lower outer diaphragm 10 set forth in claim 1, and providing a haunch 15 under the beam.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments and examples of the present invention will be described below with reference to the drawings.
Seismic reinforcement method for the existing girders bending of, and if the more to further increase the lateral strength of the existing girders 2 in the RC Building or SRC Buildings, when to restore the horizontal strength of the existing girders 2, which was damaged by an earthquake, etc. Moreover, as shown in FIG.1 and FIG.2, it implements suitably as a method of reinforcing the existing large beam 2 of a column beam joint part later using the reinforcement plate 3, PC steel rod 4, etc. later. The reinforcing plate 3 is a horizontal corner formed by the existing column 1 and the existing large beam 2 of the column beam joint when the U-shaped cross-section member (see FIG. 2) composed of the flange 3a and the web 3b is viewed in plan. It is manufactured in an L shape (see FIG. 1) that can be in close contact with the part. Reference numeral 3 ′ in FIG. 1 is a recessed portion that is aligned with the corner of the existing pillar 1. The height H of the reinforcing plate 3 is substantially the same as the height of the existing large beam 2 with which the reinforcing plate 3 is brought into contact (see FIG. 2). The reinforcing plate 3 is usually manufactured as a welded assembly of a shaped steel material or a cast steel product.
[0010]
Below, the earthquake-proof reinforcement method with respect to the bending of the existing large beam 2 using the said reinforcement plate 3, PC steel rod 4, etc. is demonstrated.
First, the reinforcing plates 3 are brought into close contact with four horizontal corner portions formed by the existing columns 1 and the existing large beams 2 of the column beam joint. The reinforcing plate 3 has its web 3 b in close contact with the side surface of the existing pillar 1 and the side surface of the existing large beam 2, and the upper flange 3 a in close contact with the lower surface of the floor slab 11. The lower flange 3 a substantially coincides with the lower surface level position of the existing large beam 2. Next, a plurality of (four in this embodiment) PC steel rods 4 are passed through the holes provided in advance at predetermined positions of the web 3b of the reinforcing plate 3 in a direction perpendicular to the axis of the existing large beam 2. As a method therefor, a method is generally used in which a hole is drilled by a core boring method in the vicinity of the column beam joint (the end of the existing beam 2) and a PC steel rod is passed. A nut 5 is screwed into both ends of the PC steel bar 4, and the web 3b of the reinforcing plate 3 is pressed against the side surface of the existing large beam 2 by tightening firmly to a predetermined torque. In the present embodiment, a portion closer to the center side than the end portion of the existing large beam 2 is driven into the existing large beam 2 by pushing a plurality of anchors 6 into the existing large beam 2 except for the portion pressed by the PC steel rod 4 in the reinforcing plate 3. The web 3b of the plate 3 is crimped to the side surface of the existing large beam 2 to complete the seismic reinforcement method for bending the existing large beam 2. As the anchor 6, a hole-in anchor or a chemical anchor is preferably employed.
[0011]
In short, the existing large beam 2 is brought into close contact with the four corners of the column beam joint portion, and the adjacent reinforcing plate 3 is pressed between the existing large beam 2 so that the existing column 1 and the existing large beam 2 are bonded. As a result, the reinforcing effect is exerted. That is, since the reinforcing plate 3 bears a part of the bending moment loaded on the existing large beam 2, the bending strength of the existing large beam 2 is increased. Of course, it is implemented as a reinforcing method that does not damage the existing pillar 1 at all. In addition, the necessary increase in bending strength can be adjusted by the size and thickness of the flange 3a and the web 3b constituting the reinforcing plate 3. In the illustrated example, the number of the PC steel bars 4 is four for one existing girder 2, but two may be sufficient depending on the required bending strength of the existing girder 2. In some cases, 5 or more are required.
[0012]
Next, the earthquake-proof reinforcement method with respect to the bending of the existing large beam which concerns on invention of Claim 1 is demonstrated.
As shown in FIGS. 3 to 5, this reinforcing method is performed by connecting the upper outer diaphragm 7 and the column cover plate 8, the beam reinforcing plate 9, and the lower outer diaphragm 10 at the column beam joint in the RC building or SRC building. It is suitably implemented as a method of reinforcing the existing large beam 2 later. Each of the components 7, 8, 9, and 10 is manufactured as a processed product of steel plate or a cast steel product. As shown in FIG. 6, the upper outer diaphragm 7 is formed of a flat plate-like member that surrounds the existing pillar 1 and has a shape that follows the planar shape of each existing large beam 2 and is divided into at least a half. The column cover plate 8 has a notch 8 ′ (substantially the same shape and the same size) corresponding to the cross-sectional shape of the existing beam 2 in the upper half. It consists of the cylindrical member which divided | segmented the square cylinder which encloses into 2 equal parts. The beam reinforcing plate 9 is a plate-like member having an inverted L-shaped cross section including a flange 9 a that abuts on the lower surface of the floor slab 11 and a web 9 b that abuts on the side surface of the existing large beam 2. The height H of the beam reinforcing plate 9 is set to be substantially the same as the beam formation of the existing large beam 2 that abuts the plate (see FIG. 4). The lower outer diaphragm 10 is formed of a flat plate member that surrounds the column cover plate 8 and that follows the planar shape of the existing large beam 2 and is divided into at least a half, that is, the upper outer diaphragm. 7 is the same shape. However, the portion of the upper outer diaphragm 7 that follows the planar shape of the existing large beam 2 has a width that can be connected and crimped by a bolt 12 that penetrates the flange 9a of the beam reinforcing plate 9 and the floor slab 11, as will be described later.
[0013]
Below, the seismic reinforcement method with respect to the bending of the existing large beam 2 using the upper outer diaphragm 7, the column cover plate 8, the reinforcing plate 9, the lower outer diaphragm 10, and the like will be described.
First, on the outer periphery of the existing pillar 1, the divided pieces of the half-shaped upper outer diaphragm 7 are attached in such a manner that the divided pieces are sequentially placed on the upper surface of the floor slab 11, and then the contact portions between the divided pieces are made into regular shapes They are joined together by means such as welding. Next, the divided pieces of the half-shaped column cover plate 8 are sequentially attached to the outer periphery of the existing column 1 in the column beam joint on the lower surface side of the floor slab 11, and the abutting portions between the half pieces are attached. They are integrally joined to the regular shape by means such as welding. Next, the beam reinforcing plate 9 is attached to each side surface of the existing large beam 2 in such a manner that the flange 9 a abuts against the lower surface of the floor slab 11 and the web 9 b abuts against the side surface of the existing large beam 2. As a result, the lower end of the web 9b coincides with the lower surface level position of the existing large beam 2 with which the beam reinforcing plate 9 is in contact. The beam reinforcing plate 9 drives the anchor 14 into the existing large beam 2 through a hole provided in the web 9b in advance, and firmly presses the anchor 14 to the existing large beam 2. As the anchor 14, a hole-in anchor, a chemical anchor, or the like is preferably employed.
[0014]
Thereafter, the divided pieces of the lower outer diaphragm 10 are sequentially attached to the outer periphery of the existing pillar 1 at the lower surface level position of the existing large beam 2, and the contact portions between the divided pieces are integrally formed into a regular shape by means such as welding. Join. Further, the contact portions of the column cover plate 8, the beam reinforcing plate 9, and the lower outer diaphragm 10 are also integrally joined by means such as welding. Finally, the flange portion 9a of the beam reinforcing plate 9 closely attached to the lower surface of the floor slab 11 and the upper outer diaphragm 7 are connected by a plurality of bolts 12 penetrating the floor slab 11 and nuts 13 screwed into the bolts. Tighten firmly and crimp. The means for joining the upper outer diaphragm 7 and the lower outer diaphragm 10 can be integrally joined by means such as bolting or riveting, in addition to the welding.
[0015]
In short, by attaching the upper outer diaphragm 7 and the column cover plate 8, the beam reinforcing plate 9, and the lower outer diaphragm 10 integrally using a bolt 12 and an anchor 14 so as to surround the column beam joint, Since the bending stress applied to the existing large beam 2 is transmitted to the upper outer diaphragm 7 and the lower outer diaphragm 10 to be borne, the reinforcing effect is produced accordingly. Of course, a possible no reinforcing method damaging the already Sonbashira all, results in increased bending strength existing girders 2.
[0016]
In the case of the seismic reinforcement method for bending of the existing large beam according to the invention of claim 2 , it is suitably implemented when the beam formation at the column beam joint is different as shown on the right side of FIG. In this case, in order to align the beam formation, a reinforcing plate 9 and a lower outer diaphragm 10 are provided with a haunch 15 below the beam on the smaller beam forming side, and concrete is filled in the hunch cavity on the lower surface of the existing large beam 2. The bending strength of the girder 2 can be increased. Even when the beam formation at the column beam joint is the same, the lower outer diaphragm 10 is lowered to increase the beam formation to further provide a haunch, and the stress center distance of the existing rebar is increased to bend the existing large beam 2. A method of increasing the yield strength can also be implemented.
[0017]
As another embodiment, in the case of a free access floor, the upper outer diaphragm 7 can be installed in an empty space. However, when it is inconvenient for the upper outer diaphragm 7 to be raised on the floor surface, as shown in FIG. 8, the floor concrete is suspended by a recess that allows the upper outer diaphragm 7 to sink to the same level as the floor surface. It is also possible to carry out in a mode in which it is formed to be embedded in the recess.
[0018]
[Effects of the present invention]
According to the seismic reinforcement method for bending of an existing girder according to the present invention, a reinforcing plate or the like is used to maintain the soundness of the column frame without damaging the existing column at all, and to rationalize the existing girder afterwards. Can be effectively reinforced. In addition, it is dry and can be carried out with a small number of on-site construction processes.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a seismic reinforcement state of an existing large beam using a reinforcing plate and a PC steel rod.
FIG. 2 is a longitudinal sectional view showing a seismic strengthening state of an existing large beam using a reinforcing plate and a PC steel bar.
FIG. 3 is a cross-sectional view showing a seismic reinforcement state of an existing large beam by an outer diaphragm or the like.
FIG. 4 is a longitudinal sectional view showing a seismic reinforcement state of an existing large beam by an outer diaphragm or the like.
5 is an exploded perspective view schematically showing each component such as an outer diaphragm shown in FIG. 4. FIG.
FIG. 6 is a plan view showing the shape of the upper outer diaphragm.
FIG. 7 is a longitudinal sectional view showing a second embodiment of the seismic reinforcement method for an existing large beam using an outer diaphragm or the like.
FIG. 8 is a longitudinal sectional view showing a third embodiment of the seismic reinforcement method for an existing large beam using an outer diaphragm or the like.
FIG. 9 is a longitudinal sectional view showing a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Existing pillar 2 Existing large beam 3 Reinforcement plate 3a Flange 3b Web 3 'Recessed part 4 PC steel bar 5 Nut 6 Anchor 7 Upper outer diaphragm 8 Column cover plate 8' Notch 9 Beam reinforcing plate 9a Flange 9b Web 10 Lower lower part Diaphragm 11 Floor slab 12 Bolt 13 Nut 14 Anchor 15 Haunch

Claims (2)

A seismic reinforcement method for bending of existing large beams in the column beam joints of reinforced concrete structures or steel reinforced concrete structures,
A process of attaching a flat plate-like upper outer diaphragm divided into a plurality of shapes in the shape of the existing pillar in a shape that surrounds the existing pillar on the outer periphery of the existing pillar on the upper surface of the floor slab;
Attaching a column cover plate divided into a plurality having a cutout portion corresponding to the cross-sectional shape of the existing large beam on the outer periphery of the existing column in the column beam joint portion on the lower surface side of the floor slab;
A step of attaching a beam reinforcing plate having an inverted L-shaped cross section to a side surface of the existing large beam, comprising a flange contacting the lower surface of the floor slab and a web contacting the side surface of the existing large beam;
A step of attaching a flat lower outer diaphragm divided into a plurality of shapes in a shape that surrounds the column cover plate and follows the planar shape of the existing large beam on the outer periphery of the existing column at the lower surface level position of the existing large beam;
A step of integrally joining the column cover plate, the beam reinforcing plate, and the contact portions of the lower outer diaphragm, respectively;
A step of crimping the flange portion of the beam reinforcing plate closely attached to the lower surface of the floor slab and the upper outer diaphragm with a plurality of bolts that penetrate the floor slab and nuts screwed into the bolt;
A step of pressure-bonding the web of the beam reinforcing plate to a side surface of the existing large beam by a plurality of anchors driven into the existing large beam;
Seismic reinforcement method for bending of existing large beams, each characterized by comprising The method for seismic reinforcement against bending of an existing large beam according to claim 1 , wherein a haunch under the beam is provided on the beam reinforcing plate and the lower outer diaphragm.

Images