JP6966874B2 - Reinforcement method of beam-column joint and reinforcement structure of beam-column joint - Google Patents

Description

The present invention relates to a technique for reinforcing a beam-column joint, and more particularly to a method and a structure suitable for seismic isolation of an existing building or reinforcement of a beam-column joint at the time of seismic retrofitting.

When performing renovation work for the purpose of seismic isolation or earthquake resistance of existing buildings, steel plate jacketing or concrete reinforcement is usually performed in order to increase the strength and rigidity of the existing skeleton. For example, Patent Document 1 discloses a technique relating to a construction method for seismic isolation of an existing building, and Patent Document 2 discloses a technique relating to seismic retrofitting of an existing building.

As a specific example, in Patent Document 1, when the seismic isolation device is installed on the pillar of the seismic isolation floor, the upper part (column-beam joint) of the pillar of the seismic isolation floor excluding the part where the seismic isolation device is installed is described. , It is shown that the lower part is reinforced with concrete. Further, in Patent Document 1, a support jig for temporarily supporting a part of a column is installed in order to install a seismic isolation device after the column including the column-beam joint is reinforced with concrete. It is shown to do.

Further, Patent Document 2 discloses a technique for ensuring the fixation of the beam main bar of the additional striking portion when the additional striking reinforcement with concrete is performed on the existing beam. Specifically, a through hole is formed in the horizontal direction with respect to a part of the skeleton (other existing beams) arranged orthogonally to the extension direction of the beam to be reinforced, and the beam main bar is provided in this through hole. Let it be inserted. Then, the beam main bar is penetrated through the perforated through hole and fixed.

Japanese Unexamined Patent Publication No. 2004-124579 Japanese Unexamined Patent Publication No. 2006-125022

In recent years, repair work for seismic isolation and seismic isolation as described above has been actively carried out. However, the technique disclosed in Patent Document 1 mainly indicates the installation and process of a jig for installing a seismic isolation device, and is a technique for preferably performing additional concrete casting at a beam-column joint. There is no specific disclosure of. Further, according to the technique disclosed in Patent Document 2, it is considered that the fixing of the beam main bar can be ensured. However, in order to implement the technique, it is necessary to form through holes in the existing skeleton as many as the number of beam main bars, which requires a great deal of labor. In addition, it is considered difficult to apply in the case of a building where the skeleton (beam) intersecting with the beam to be reinforced with concrete is not orthogonal. In addition, it is also considered difficult to carry out additional striking work on all the beams that intersect around the pillar.

Therefore, it is an object of the present invention to provide a method for reinforcing a beam-column joint that can be constructed and a reinforcing structure regardless of the arrangement form of a plurality of beams arranged around the column.

The method for reinforcing a beam-column joint according to the present invention for achieving the above object is a method for reinforcing a beam-column joint in an existing building, and the beam is provided for each of a plurality of beams arranged around the column. An opening step of forming a hole that penetrates the through hole in the horizontal direction, a reinforcing member arranging step of inserting a reinforcing member through each of the through holes, and an insertion through the through hole formed in the adjacent beam. The reinforcing member connecting step of connecting the reinforcing members in the longitudinal direction to form the reinforcing member in an annular shape, joining the beam main bar of the additional striking portion to the reinforcing member, and arranging the shear reinforcing bar for the beam main bar. It is characterized by having a reinforcing bar arranging step and a placing step of filling concrete around the beam including the additional striking portion.

Further, in the method for reinforcing a column-beam joint having the above-mentioned characteristics, in the reinforcing bar arranging step, after an anchor is placed on the beam, the shear reinforcing bar is fixed to the anchor. .. By having such a feature, when fixing the shear reinforcing bar, it is not necessary to form a through hole in the beam, and the labor can be reduced.

Further, another means in the method for reinforcing the beam-column joint according to the present invention for achieving the above object is a method for reinforcing the beam-column joint in an existing building, and each of a plurality of beams arranged around the column is used. On the other hand, an opening step of forming a through hole penetrating the floor slab along both side surfaces of the beam, a reinforcing member arranging step of arranging a reinforcing member around the column, and forming the reinforcing member in an annular shape. Includes a reinforcing member connecting step, a reinforcing bar arranging step of joining the beam main bar of the additional striking portion to the reinforcing member, and arranging the shear reinforcing bar for the beam main bar through the through hole, and the additional striking portion. It is characterized by having a casting step of filling concrete around the beam. Even if such a method is adopted, the same effect as the above method can be obtained.

Further, in the method for reinforcing a beam-column joint having the above-mentioned characteristics, the reinforcing member is a member having an L-shaped or T-shaped cross-sectional shape, and the column is used as a base point on the inner peripheral side and the outer peripheral side. Arrange so that it has a horizontal plane. By having such a feature, it is possible to give strength to the reinforcing member and to join the beam main bar to the horizontal plane.

Further, the reinforcing structure of the beam-column joint for achieving the above object is a reinforcing structure of the beam-column joint of the existing building, and the annular reinforcing member arranged on the outer peripheral side of the column and the annular reinforcing member are provided. A beam main bar arranged along the extending direction of the beam as a base point, a shear reinforcing bar arranged intersecting the beam main bar, a concrete layer covering the beam, the beam main bar, and the shear reinforcing bar. It is characterized by having.

Further, in the reinforcing structure of the beam-column joint having the above-mentioned characteristics, the annular reinforcing member is arranged so as to horizontally penetrate a plurality of the beams arranged around the column. By having such a feature, it becomes possible to arrange a reinforcing member in a layer having a beam and adopt a reinforcing structure.

Further, in the reinforcing structure of the column-beam joint having the above-mentioned characteristics, an anchor for fixing the shear reinforcing bar is placed in the beam. By having such a feature, when fixing the shear reinforcing bar, it is not necessary to form a through hole in the beam, and the labor can be reduced.

Further, in the reinforcing structure of the column-beam joint having the above-mentioned characteristics, the shear reinforcing bars are arranged so as to penetrate the floor slab along both side surfaces of the beam. By having such a feature, it becomes possible to arrange a reinforcing member on the upper floor of the floor having the beam to be reinforced and adopt the reinforcing structure.

Further, in the reinforcing structure of the column-beam joint having the above-mentioned characteristics, the reinforcing member has an L-shaped or T-shaped cross-sectional shape. By having such a feature, it becomes possible to use a general-purpose steel material as a reinforcing member and to join the beam main bar to the horizontal plane or the vertical plane thereof. Flare welding is generally used as the joining means, but if a hole is provided in the vertical surface and fastened by a bolt-nut method, the welding length can be shortened and the reinforcing member can be made smaller. In addition, when there is a vertical surface, the bearing area can be increased and the rigidity of the ring can be increased compared to flat steel (flat bar). Therefore, the reinforcing member having an L-shaped or T-shaped cross-sectional shape is effective in transmitting the stress from the reinforcing bar to the column while maintaining the overall shape of the ring.

According to the method of reinforcing the beam-column joint having the above-mentioned characteristics and the reinforcing structure, the beam-column joint can be reinforced regardless of the arrangement form of a plurality of beams arranged around the column. can.

It is a flow chart about the reinforcement method of the column-beam joint part which concerns on embodiment. It is a top view which shows the example of the skeleton to which the reinforcement method of a beam-column joint and the reinforcement structure are applied. It is a top view which shows the state which the through hole was formed in each of the plurality of beams constituting the skeleton. It is a top view which shows the state which the reinforcing member is inserted through the through hole formed in each of a plurality of beams. It is a top view which shows the state which formed the annular body by connecting the reinforcing member inserted through a through hole in the longitudinal direction. It is a top view which shows the state which arranged the beam main bar with the reinforcing member which made into an annular body as a base point. It is a figure which shows the joint state of the beam main bar with respect to the reinforcing member of an L-shaped cross section. It is a figure which shows the joint state of the beam main bar with respect to the reinforcing member of the cross section T-shaped. It is a top view which shows the state which arranged the shear reinforcing bar (star wrap) around the beam main bar, and also arranged the column main bar and a shear reinforcing bar (hoop). It is sectional drawing which shows the state of a beam after reinforcement. It is sectional drawing for demonstrating an example using an anchor regarding the arrangement of a shear reinforcing bar with respect to a beam main bar. It is a top view which shows the state of a skeleton after reinforcement of a beam-column joint. It is a front view for demonstrating an example of the case of performing seismic isolation repair to the skeleton after reinforcing a column-beam joint. It is a top view for demonstrating the deformation example which made the shape of a column and the arrangement form of a beam different. It is a front view which shows the structural example in the case of arranging the reinforcing member on the upper floor of the floor which has a beam to be reinforced.

Hereinafter, the method for reinforcing the beam-column joint portion of the present invention and the embodiment relating to the reinforcing structure of the beam-column joint portion will be described in detail with reference to the drawings.
The application of the method for reinforcing the beam-column joint according to the present embodiment will be described by exemplifying a flow chart shown in FIG. 1 and a progress configuration diagram shown in FIGS. 2 to 12. FIG. 2 is an example of a skeleton 10 to which a method for reinforcing a beam-column joint according to an embodiment (hereinafter, simply referred to as a reinforcement method) is applied, and is a state of the column 12 and a beam 14 connected around the column 12. Is shown in a plan view. In the skeleton 10 shown in FIG. 2, a plurality of (five in the example shown in FIG. 2) beams 14 are radially connected around the columnar column 12. The arrangement interval of each beam 14 (arrangement angle of the beam 14) is irregular, and a portion where the angle formed between the adjacent beams 14 is an acute angle and a portion where the angle is an obtuse angle coexist. It is difficult to apply the conventional reinforcing method to the skeleton 10 having such a column-beam joint.

In the method for reinforcing a beam-column joint according to the embodiment, first, a through hole 16 is formed for each beam 14. As shown in FIG. 3, the through hole 16 is formed horizontally along a direction orthogonal to the extending direction of the beam 14. The distance L from the pillar 12 to the through hole 16 may be any distance as long as it is possible to install a tool for drilling the beam 14 and work, and the specific value is not limited. However, it is desirable to approximate the distance L from the column 12 in the through hole 16 formed in each of the plurality of beams 14. Further, the diameter of the through hole 16 may be a diameter through which the reinforcing member 18, which will be described in detail later, can be inserted. The through hole 16 is formed in the beam 14 so as not to damage the steel frame or the like (not shown) constituting the beam 14. Here, at the time of drilling the beam 14, it is preferable to support the points indicated by the broken line circles in FIG. 3 with a jack or the like (not shown) in preparation for a cross-sectional defect of the beam 14. For the sake of explanation, it is described that the through hole 16 is formed horizontally along the direction orthogonal to the extending direction of the beam 14. However, the term "horizontal" as used herein is not strict and includes an error in the drilling operation (opening step: step 10).

Next, as shown in FIG. 4, the reinforcing member 18 is inserted through the through hole 16 provided in each beam 14 (reinforcing member arranging step: step 20). After the reinforcing member 18 is inserted into the through hole 16, as shown in FIG. 5, the reinforcing members 18 arranged adjacent to each other are connected in the longitudinal direction to form the reinforcing member 18 in an annular shape. The reinforcing member 18 may be connected by means such as welding, and if there is a gap between the reinforcing member 18 through which the through hole 16 is inserted and the reinforcing member 18 arranged adjacent to the reinforcing member 18, the reinforcing members 18 are connected to each other. The connecting member 18a may be separately arranged in the above (reinforcing member connecting step: step 30).

Here, the reinforcing member 18 (including the connecting member 18a) constitutes a so-called L-shaped cross section having a vertical surface 18b and a horizontal plane 18c as shown in FIG. 7 in the installed state. Similarly, as a form having the vertical plane 18b and the horizontal plane 18c, a so-called T-shaped cross section as shown in FIG. 8 may be formed.

After the reinforcing member 18 is arranged in an annular shape, the through hole 16 formed in the beam 14 is filled with a grout material to close the through hole 16 and fix the reinforcing member 18. After the grout material is hardened, the beam main bar 20 is joined as shown in FIG. The beam main bar 20 is arranged along the extending direction of each beam 14 with the reinforcing member 18 as a base point. As shown in FIGS. 7 and 8, the beam main bar 20 is joined by welding a part of the horizontal plane 18c constituting the reinforcing member 18. The number of beam main bars 20 to be arranged for each beam 14 may be appropriately selected according to the dimensions, strength, and the like of the beam 14 to be additionally striked.

After finishing the joining of the beam main bar 20, a shear reinforcing bar (star wrap) 22 is arranged around the beam main bar 20 as shown in FIG. Here, at least the upper end of the beam 14 of the existing building is embedded in or in close contact with the floor slab 40 such as the ceiling (floor on the upper floor), as shown in the cross-sectional form in FIG. Therefore, the shear reinforcing bar 22 arranged so as to cover the beam main bar 20 is arranged after drilling a through hole in the beam 14.

However, when a through hole for arranging all of the plurality of shear reinforcing bars 22 to be arranged is formed in the beam 14, the strength of the beam 14 may decrease or the through hole may not be formed due to an internal steel frame (not shown). In such a case, as shown in FIG. 11, an anchor 24 is driven into the side surface of the beam 14, and the anchor 24 ensures the strength of the bonded state between the existing beam 14 and the additional casting portion (additional concrete 30). You can do it. In such a configuration, the shear reinforcing bars 22 are arranged so as to surround the main bars 20 arranged on both sides of the beam 14. Then, the tip of the anchor 24 is positioned within the range of the shear reinforcing bar 22 surrounding the main bar 20. Then, if necessary, a retaining member 24a may be provided at the tip of the anchor 24.

Further, when the shear reinforcing bars 22 are arranged in this way, the shear reinforcing bars 22a connecting the two are also between the shear reinforcing bars 22 arranged on both sides of the beam 14, and the main bars orthogonal to the shear reinforcing bars 22a. It may be configured to arrange 20a. This is because it is possible to connect the shear reinforcing bars 22 arranged apart from each other on both sides of the beam 14 to form an integrated additional striking portion (reinforcing bar arrangement). Step: Step 40).

In this reinforcing bar arranging step, the column main bar 26 and the shear reinforcing bar (hoop) 28 for reinforcing the column 12 are provided before, after, or at the same time as the placement of the shear reinforcing bar 22 in the additional striking portion of the beam 14. Deploy.

After completing the reinforcing bar placement process, formwork (not shown) is placed around the main bars (beam main bar 20, column main bar 26) and shear reinforcing bars 22 and 28, and concrete (concrete for additional casting 30) is filled. Perform the casting work. After the filled concrete for additional casting 30 is hardened, the reinforcement of the column-beam joint in the skeleton 10 is completed by removing the formwork (casting step: step 50).

[Reinforcement structure]
The skeleton 10 in which the column-beam joint is reinforced in this way has the following structural features. That is, as shown in FIG. 12, it has a reinforcing member 18, a beam main bar 20, a shear reinforcing bar 22, a column main bar 26, a shear reinforcing bar 28, and concrete 30 for additional casting. The reinforcing member 18 is an annular structure composed of a steel material having an L-shaped or T-shaped cross section and horizontally penetrating a plurality of beams 14 arranged around the columns 12. The beam main bar 20 is composed of a metal rod, and is arranged along the extending direction of the beam 14 to be reinforced with the reinforcing member 18 as a base point. The shear reinforcing bar 22 is also composed of a metal rod and is arranged so as to cover the periphery of the plurality of beam main bars 20 in a direction orthogonal to the beam main bar 20. A plurality of shear reinforcing bars 22 are arranged along the extending direction of the beam main bar 20.

The column main bar 26 and the shear reinforcing bar 28 are composed of metal rods like the beam main bar 20 and the shear reinforcing bar 22. The column main bar 26 is arranged along the column 12 on the outer periphery of the column 12, and the shear reinforcing bar 28 is arranged in a direction orthogonal to the column main bar 26 so as to cover the plurality of column main bars 26.

The additional concrete 30 is a concrete layer that covers the above-mentioned beam main bar 20, shear reinforcing bar 22, column main bar 26, and shear reinforcing bar 28, and constitutes the exterior of the column 12 and the beam 14 after reinforcement.

According to the method of reinforcing the beam-column joint having such a configuration and the reinforcing structure, the beam-column joint can be reinforced regardless of the arrangement form of the plurality of beams 14 arranged around the column 12. It will be possible.

[About seismic isolation repair]
When installing the seismic isolation device after reinforcing the beam-column joint as described above, as shown in FIG. 13, a temporary bearing 32 is installed on the column 12, and the temporary bearing 32 is installed. A temporary bearing portion 34 such as a jack is arranged between the beam 14 and the reinforced beam 14 (installation of bearings).

After arranging the temporary bearing portion 34, a part of the pillar 12 is cut in order to secure a space for installing a seismic isolation device (not shown). In addition, it is not decided to perform additional striking on the part of the pillar 12 related to cutting.

In this way, by performing seismic isolation repair after reinforcing the column-beam joint, the strength and rigidity of the columns 12 and beams 14 in the skeleton 10 are improved, and the deformation is concentrated on the seismic isolation device. It is possible to bear the additional stress. In addition, when an earthquake occurs, the skeleton (pillars 12 and beams 14) is less likely to be deformed, the deformation is concentrated on the seismic isolation device, and the building becomes longer in period, resulting in an earthquake to the upper part of the seismic isolation layer. The force will be reduced. Therefore, a sufficient seismic isolation effect can be obtained. In addition, as an effect of improving the proof stress and rigidity of the pillar 12, it is possible to install a support work for receiving the axial force of the pillar 12.

[Modification example]
In the above embodiment, the pillar 12 has a cylindrical shape, and the beams 14 provided around the pillar 12 have a non-uniform arrangement angle. However, the method for reinforcing the beam-column joint and the reinforcing structure according to the present embodiment can be applied to the skeleton 10 having the beams 14 evenly arranged on the prism-shaped columns 12 as shown in FIG. ..

Specifically, the skeleton 10 shown in FIG. 14 includes a pillar (pentagonal pillar) 12 having a pentagonal cross section. The beams 14 are arranged radially with each apex portion of the pentagon as a base point.

When the method (structure) for reinforcing the column-beam joint is applied to the skeleton 10 having such a configuration, the through hole 16 is formed for each beam 14 as in the above embodiment. Then, the reinforcing member 18 is inserted through the through hole formed in the beam 14. Here, in the above embodiment, the reinforcing member 18 is circular in accordance with the outer peripheral shape of the pillar 12. Similarly, in this modification, the form of the reinforcing member 18 may be a circle that fits inside the inscribed circle with respect to the outer shape of the column 12 (a circle that is not exposed to the outside). By forming the reinforcing member 18 in such a form, it is possible to avoid concentration of stress generated at the corners. Further, by matching the outer shape of the column 12 after reinforcement with that before reinforcement, it is possible to suppress the collapse of the overall design and the change in impression due to the reinforcement. In FIG. 14, the outer shape of the additional striking portion in the reinforcing member 18 arrangement portion is indicated by a two-dot chain line.

Further, in each of the above embodiments, the reinforcing member 18 is described so as to be arranged in the layer having the beam 14 to be reinforced. However, as shown in FIG. 15, the method for reinforcing a beam-column joint according to the present invention can be applied even if the reinforcing member 18 is arranged on the upper floor of the floor provided with the beam 14 to be reinforced.

Specifically, first, a through hole 42 is formed in the floor slab 40 on the upper floor (hereinafter, simply referred to as the upper floor) of the beam 14 to be reinforced. The through hole 42 is formed along both side surfaces of the plurality of beams 14 arranged around the pillar 12 (opening step). Next, the reinforcing member 18 is arranged around the pillar 12 on the upper floor. The reinforcing member 18 is arranged so as to cover the circumference of the pillar 12 in an annular shape by using a plurality (at least two) arc-shaped members. In FIG. 15, the reinforcing member 18 shows a side surface (front) form on the right side and a cross-sectional form on the left side with the center line indicated by the alternate long and short dash line as the base point (reinforcing member arrangement step). Next, the reinforcing members 18 arranged so as to cover the pillars 12 are connected to form an annular shape (reinforcing member connecting step).

Subsequent steps are the same as in the above-described embodiment. That is, the beam main bar 20 is arranged along the extending direction of the beam 14 with the reinforcing member 18 as the base point. After that, the shear reinforcing bars 22 are arranged so as to cover the plurality of beam main bars 20 arranged around the beams 14. Here, the shear reinforcing bar 22 is arranged so as to penetrate the through hole 42 formed in the floor slab 40 (reinforcing bar placement step). After that, the additional concrete 30 is placed in the range covering the beam 14, the column 12, the beam main bar 20, the shear reinforcing bar 22, and the like (casting step).

Even when such a method and structure are adopted, the same effect as that of the above embodiment can be obtained. Further, since the reinforcing member 18 can be arranged on the upper floor of the floor having the beam 14 to be reinforced to form the reinforcing structure, the additional striking area of the ceiling portion at the column-beam joint is reduced, and after construction. It is possible to reduce the feeling of oppression of the ceiling portion in.

In the above embodiment, it is described that welding is mainly used for the connection and joining between the members. However, if it is a method that can connect and join members reliably, easily, and inexpensively, the method may be adopted instead of welding.

10 ………… Frame, 12 ………… Pillar, 14 ………… Beam, 16 ………… Through hole, 18 ………… Reinforcing member, 18a ………… Connecting member, 18b ………… Vertical surface, 18c ………… Horizontal plane, 20, 20a ……… Beam main bar, 22, 22a ……… Shear reinforcement (star wrap), 24 ……… Anchor, 24a ……… Retaining member, 26 ……… Column main bar, 28 ……… Shear reinforcement (hoop), 30 ……… Concrete for additional casting, 32 ……… Temporary bearings, 34 ……… Temporary bearings, 40 ……… Floor slabs, 42 ……… Through holes.

Claims (4)

It is a method of reinforcing the beam-column joint of an existing building.
An opening step of forming a through hole that horizontally penetrates the beam for each of the plurality of beams arranged around the column.
A reinforcing member arranging step of inserting a reinforcing member through each of the through holes formed at the end of the beam, and a step of arranging the reinforcing member.
A reinforcing member connecting step of connecting the reinforcing members inserted in the through hole formed in the adjacent beam in the longitudinal direction to form the reinforcing member in an annular shape.
A reinforcing bar arranging step of joining the beam main bar of the additional striking portion to the reinforcing member and arranging a shear reinforcing bar for the beam main bar.
It has a casting step of filling concrete around the beam including the reinforcing member, the beam main bar, and the shear reinforcing bar to form the additional striking portion.
A method for reinforcing a column-beam joint, wherein the reinforcing member constitutes an annular structure that horizontally penetrates a plurality of the beams. The method for reinforcing a beam-column joint according to claim 1, wherein the shear reinforcing bar is inserted through the through hole and arranged in the additional striking portion. The reinforcing member is a member having an L-shaped or T-shaped cross-sectional shape.
The method for reinforcing a beam-column joint according to claim 1 or 2 , wherein the column is arranged so as to have a vertical surface on the inner peripheral side and a horizontal surface on the outer peripheral side with the column as a base point. It is a reinforcing structure of the column-beam joint of an existing building.
An annular reinforcing member placed on the outer peripheral side of the column and
A beam main bar arranged along the extension direction of the beam with the annular reinforcing member as a base point,
Shear reinforcements arranged intersecting the beam main bars and
A concrete layer covering the beam, the beam main bar, and the shear reinforcing bar,
Have a,
The annular reinforcing member is a reinforcing structure for a column-beam joint, characterized in that the annular reinforcing member is arranged so as to horizontally penetrate a plurality of the beams arranged around the column.

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