JP7510322B2 - Self-repairing structure for beam-column joints - Google Patents

Description

This disclosure relates to a self-repairing structure for a joint between a concrete column and a beam.

As shown in Figure 8, a column-beam joint 1 in a reinforced concrete building is the part where a reinforced concrete column 2 and a reinforced concrete beam 3 intersect. Previously, as shown in Figure 8 (B), designs were based on the assumption that no cracks would occur within the column-beam joint 1 during an earthquake, but bending cracks 4 would occur in the beam 3, resulting in beam bending yield failure, as shown in Figure 8 (B). However, in recent years, it has been pointed out that when the column-beam strength ratio (the ratio of bending moments at the node positions when the critical sections of the column 2 and beam 3 reach their ultimate bending strength) is small, as shown in Figure 8 (A), a diagonal crack 5 will occur from the corner within the column-beam joint 1, causing joint yield failure in which the beam main reinforcement and column main reinforcement will yield in tension within the column-beam joint 1.

One method of repairing damage such as cracks caused by this type of joint yield failure is to inject organic resin into the cracks from the side of the column-beam joint. Patent Document 1 also describes attaching a continuous fiber sheet to the side of the column-beam joint.

JP 2016-075145 A

However, beams are often attached to a single beam-column joint in a cross shape when viewed from above. In these cases, the sides of the beam-column joint are not exposed, and the repair method described above cannot be used.

In view of these problems, the present invention aims to provide a self-repairing structure for column-beam joints that can also be applied to column-beam joints where beams are attached in a cross shape when viewed from above.

A self-repairing structure (10, 20, 30, 40, 50) for a column-beam joint (1) according to an embodiment of the present invention includes a concrete column (2), a concrete beam (3) joined to the column (2), and repair tools (11, 21, 31) fixed to each of the corners defined by the side of the column (2) and the upper and lower surfaces of the beam (3) connected to the side, each of the repair tools (11, 21, 31) including a sheet (12, 22) fixed to the side of the column (2) and the upper or lower surface of the beam (3), and a repair material (13, 32) having fluidity held in the sheet (12, 22). The repair material (13, 32) may be configured to be held in a sealed state, to come out of the sealed state in the event of an earthquake of a predetermined magnitude or greater, and to harden in a predetermined time.

With this configuration, the column-beam joint can be repaired using a repair tool attached to the corner defined by the side of the column and the top and bottom surfaces of the beam, making it possible to repair even column-beam joints where the beam is attached in a cross shape when viewed from above.

In one embodiment of the present invention, the self-repairing structure (20, 30, 40, 50) of the column-beam joint (1) is characterized in that, in the above configuration, the sheet (22) includes an inner layer (23) and an outer layer (24) that does not allow the repair material (13, 32) to pass through, and holds the repair material (13, 32) on the inside of the outer layer (24). Here, with regard to the terms "inside" and "outside", the side approaching the column or beam is the "inside" side, and the side away from the column or beam is the "outside" side.

With this configuration, the repair material cannot penetrate the outer layer, making it easier for it to penetrate into cracks in the column-beam joints without leaking to the outside.

In one embodiment of the present invention, the self-repairing structure (20, 30, 40, 50) of the column-beam joint (1) is characterized in that, in the above configuration, the inner layer (23) is made of a material that breaks in the event of an earthquake of a predetermined magnitude or greater, the outer layer (24) is made of a material that is more elastic than the inner layer (23), and the repair material (13, 32) is disposed inside the inner layer (23) or between the inner layer (23) and the outer layer (24).

With this configuration, the repair material is protected by the inner layer, so it can be held stably.

In one embodiment of the present invention, the self-repair structure (30, 40, 50) of the column-beam joint (1) is characterized in that, in any of the above configurations, the repair material (32) includes a first component (33) and a second component (34) that are held separately from each other in the sheet (22). The first component and the second component are preferably water and an inorganic material, or a base agent and a hardener for the base agent.

With this configuration, by separating and storing the repair material into two components, it is possible to prevent the quality of the repair material from deteriorating until an earthquake of a specified magnitude or greater occurs.

In one embodiment of the present invention, the self-repairing structure (50) of the column-beam joint (1) in any of the above configurations further includes a plate (51) attached to the side of the column (2) and the upper or lower surface of the beam (3) so as to cover the repair tool (11, 21, 31) at each of the corners, and the plate (51) includes a vertical portion (52) attached along the side of the column (2) and a horizontal portion (53) attached to the upper or lower surface of the beam (3) and having a length shorter than the vertical length of the vertical portion (52) in the extension direction of the beam (3).

With this configuration, the vertical portion is longer than the horizontal portion, so the bending strength of the column is greater than the bending strength of the beam, and the column-beam strength ratio is greater, which makes it more likely that beam yield failure will occur rather than joint yield failure, and damage within the column-beam joint is suppressed.

The present invention provides a self-repairing structure for column-beam joints that can also be applied to column-beam joints where beams are attached in a cross shape when viewed from above.

FIG. 1 is a vertical cross-sectional view showing a self-repairing structure of a column-beam joint according to a first embodiment; Illustrative diagram of joint yield failure FIG. 1 is an explanatory diagram showing a self-repair structure of a column-beam joint according to the first embodiment during an earthquake. FIG. 11 is a longitudinal cross-sectional view showing a self-repairing structure for a column-beam joint according to a second embodiment. FIG. 13 is a longitudinal sectional view showing a self-repairing structure for a column-beam joint according to the third embodiment FIG. 13 is a longitudinal sectional view showing a self-repairing structure of a column-beam joint according to a fourth embodiment. FIG. 13 is a longitudinal sectional view showing a self-repairing structure of a column-beam joint according to the fifth embodiment. Schematic diagram showing the type of failure of a beam-column joint during an earthquake (A: joint yield failure, B: beam bending yield failure)

Embodiments of the present invention will be described below with reference to the drawings. Note that reinforcing bars are omitted in the drawings showing concrete cross sections.

Figure 1 shows a self-repairing structure 10 according to the first embodiment at a column-beam joint 1. The column-beam joint 1 is an intersection between a column 2 made of reinforced concrete and a beam 3 made of reinforced concrete. The column 2 has a rectangular cross section, and the beam 3 has a rectangular cross section perpendicular to its extension direction. The beam 3 also extends in a direction perpendicular to the paper surface of Figure 1 and intersects in a cross shape in a plan view. Note that the beam 3 may extend in one, two (e.g., two directions that form an angle of 90° or 180° in a plan view) or three (e.g., T-shaped in a plan view) directions from the side of the column-beam joint 1, the beam 3 may intersect at an angle other than 90°, and the cross-sectional outline of the column 2 and the beam 3 may be a shape other than a rectangle.

The self-repairing structure 10 comprises a column 2, a beam 3 joined to the column 2, and a repair tool 11 fixed to the corners defined by the side of the column 2 and the upper and lower surfaces of the beam 3 connected to the side. Although not shown, the repair tool 11 is also provided at each of the corners defined by the side of the column 2 and the upper and lower surfaces of the beam 3 extending in a direction perpendicular to the paper surface of the figure. The repair tool 11 comprises a sheet 12 fixed to the corners and a repair material 13 having fluidity held by the sheet 12.

The sheet 12 is fixed to the side of the column 2 and the upper or lower surface of the beam 3 at the corners, forming an L-shape when viewed from the side. The sheet 12 is fixed to the column 2 and beam 3 by, for example, gluing.

The repair material 13 is held in the sheet 12 in a sealed state by a thin film. The thin film breaks in the event of an earthquake of a predetermined scale or greater. The repair material 13 may be sealed by a sheet 12 having a sealing effect and whose surface on the column 2 and beam 3 side breaks in the event of an earthquake of a predetermined scale or greater, instead of a thin film. The repair material 13 has fluidity and hardens in a predetermined time after being released from a sealed state. For example, the repair material 13 is a dry solidification type that hardens when the water or solvent in the repair material 13 evaporates, or a chemical reaction type that hardens by chemically reacting with moisture in the air, the sheet, or the column-beam joint 1. The repair material 13 is, for example, a liquid adhesive. The repair material 13 may be held inside the sheet 12, or may be held on the surface of the sheet 12 on the column 2 and beam 3 side. When the repair material 13 is held inside the sheet 12, the sheet 12 is made of a material that allows the repair material 13 to move toward the cracks that have occurred in the column-beam joint 1 during an earthquake of a predetermined scale or greater, such as a woven fabric, nonwoven fabric, sponge-like resin, or resin that breaks during an earthquake of a predetermined scale or greater. When a resin that breaks during an earthquake of a predetermined scale or greater is used as the sheet 12, it is preferable to make the corners of the L-shape more likely to break, such as by providing a thin-walled portion at the corners. In addition, when the repair material 13 is held on the surface of the sheet 12 facing the column 2 and beam 3, the sheet 12 is preferably made of a material that is impermeable to the repair material 13 and is difficult to break during an earthquake, such as a polyethylene terephthalate sheet, but it may also be made of a material that allows the repair material 13 to penetrate and seep out when it is released from a sealed state, such as a woven fabric, nonwoven fabric, sponge-like resin, etc.

Figure 2 is an explanatory diagram that shows the shaking of the column 2 and the beam 3 when joint yield failure occurs during an earthquake. As shown in Figure 2 (A), during an earthquake of a certain magnitude or more, cracks occur along the diagonal of the column-beam joint 1, which is rectangular in vertical cross section, and the column 2 and the beam 3 rotate. In the illustrated state, the triangular parts extending from the upper and lower columns 2 move counterclockwise, and the triangular parts extending from the left and right beams 3 move clockwise. Next, as shown in Figure 2 (B), the triangular parts extending from the upper and lower columns 2 move clockwise, and the triangular parts extending from the left and right beams 3 move counterclockwise. As shown in Figure 2 (C), the triangular parts extending from the upper and lower columns 2 move counterclockwise again, and the triangular parts extending from the left and right beams 3 move clockwise. By repeating this rotational movement, a crack 5 develops along the diagonal as shown in Figure 2 (D).

Figure 3 is an explanatory diagram showing the joint yield failure during an earthquake in the self-repairing structure 10 according to the first embodiment. The movement of the triangular parts divided along the diagonal line in the column-beam joint 1 is the same as that shown in Figure 2. In the event of an earthquake of a certain scale or greater, the thin film sealing the repair material 13 breaks, allowing the repair material 13 to move. As shown in Figure 3 (A), when the triangular parts extending from the upper and lower columns 2 move counterclockwise and the triangular parts extending from the left and right beams 3 move clockwise, the crack gaps at the upper right and lower left corners of the column-beam joint 1 and the central gap along the diagonal line from the upper left to the lower right are widened. At this time, the repair material 13 held by the upper right and lower left sheets 12 penetrates into the crack gaps at the upper right and lower left corners of the column-beam joint 1.

Next, as shown in FIG. 3(B), when the triangular parts extending from the upper and lower columns 2 move clockwise and the triangular parts extending from the left and right beams 3 move counterclockwise, the crack gaps at the upper left and lower right corners of the column-beam joint 1 widen and the cracks in the center part along the diagonal line from the upper left to the lower right narrow, while the crack gaps at the upper right and lower left corners narrow and the crack gaps in the center part along the diagonal line from the upper right to the lower left widen. At this time, the repair material 13 held in the upper left and lower right sheets 12 and corners penetrates into the crack gaps at the upper left and lower right corners of the column-beam joint 1. Also, a part of the repair material 13 that penetrated from the upper right and lower left corners is pushed out toward the center part of the diagonal line, and another part is pushed out toward the upper right and lower left sheets 12. The repair material 13 pushed out toward the sheet 12 is held between the corners and the sheet 12 and/or inside the sheet 12.

Next, as shown in FIG. 3(C), when the triangular parts extending from the upper and lower columns 2 move counterclockwise and the triangular parts extending from the left and right beams 3 move clockwise, the crack gaps at the upper right and lower left corners of the column-beam joint 1 widen and the cracks in the center part along the diagonal line from the upper right to the lower left narrow, while the crack gaps at the upper left and lower right corners narrow and the crack gaps in the center part along the diagonal line from the upper left to the lower right widen. At this time, the repair material 13 held in the upper right and lower left sheets 12 and corners penetrates into the crack gaps at the upper right and lower left corners of the column-beam joint 1. Also, a part of the repair material 13 that penetrated from the upper left and lower right corners is pushed out toward the center part of the diagonal line, and another part is pushed out toward the upper left and lower right sheets 12. The repair material 13 pushed out toward the sheet 12 is held between the corners and the sheet 12 and/or inside the sheet 12.

The movements of Figure 3 (B) and Figure 3 (C) are repeated alternately, allowing the repair material 13 to reach every corner of the crack. When the earthquake subsides, as shown in Figure 3 (D), the repair material 13 hardens while still being injected into the crack 5, repairing the crack 5.

Because the repair tool 11 is provided at the corner defined by the column 2 and the beam 3, the self-repairing structure 10 can also be applied to a column-beam joint 1 in which the beams 3 extend on all four sides and are attached in a cross shape when viewed from above.

Next, a self-repairing structure 20 according to a second embodiment of the present invention will be described with reference to FIG. 4. In the description, the configurations common to the first embodiment will be omitted and the same reference numerals will be used. The self-repairing structure 10 according to the second embodiment differs from the first embodiment in the structure of the repair tool 21.

The self-repairing structure 20 comprises a column 2, a beam 3, and a repair tool 21 fixed to each of the corners defined by the side of the column 2 and the upper and lower surfaces of the beam 3 connected to the side. FIG. 4 shows the self-repairing structure 20 attached to the side of the column 2 and the upper surface of the beam 3. Repair tools 21 are also provided at other corners not shown. The repair tool 21 comprises a sheet 22 fixed to the corner and a hardenable, fluid repair material 13 held by the sheet 22.

The sheet 22 includes an inner layer 23 that holds the repair material 13 and an outer layer 24 through which the repair material 13 does not permeate. The inner layer 23 abuts against the column 2 and the beam 3, and the outer layer 24 abuts against the surface of the inner layer 23 opposite to the surface abutting against the column 2 and the beam 3. The inner layer 23 is made of a material that allows the repair material 13 to move toward the cracks that have occurred in the column-beam joint 1 during an earthquake of a predetermined scale or more, such as a woven fabric, a nonwoven fabric, a sponge-like resin, or a resin that breaks during an earthquake of a predetermined scale or more. When a resin that breaks during an earthquake of a predetermined scale or more is used as the inner layer 23, it is preferable to make the corners of the L-shape easy to break, for example by providing a thin-walled portion at the corners. The outer layer 24 is made of a material that is difficult to break and has elasticity so that it does not break even during an earthquake of a predetermined scale or more that breaks the thin film that seals the repair material 13. The outer layer 24 is preferably liquid-impermeable. For example, the outer layer 24 is made of a polyethylene terephthalate sheet. It is preferable that the outer layer 24 has a contour that is the same as or larger than that of the inner layer 23 so as to prevent the repair material 13 from leaking.

The repair material 13 is held inside the outer layer 24 of the sheet 22. If the inner layer 23 is made of a permeable material such as a woven fabric, a nonwoven fabric, or a sponge-like resin, the repair material 13 is placed on the surface of the inner layer 23 facing the columns 2 and beams 3, inside the inner layer 23, or between the inner layer 23 and the outer layer 24. If the inner layer 23 is made of a material that does not allow the repair material 13 to pass through until it breaks, such as a resin that breaks in the event of an earthquake of a predetermined magnitude or greater, the repair material 13 is placed inside the inner layer 23, or between the inner layer 23 and the outer layer 24.

When an earthquake of a certain magnitude or greater occurs, the thin film breaks and the repair material 13 escapes from the sealed state. Since the repair material 13 cannot penetrate the outer layer 24, it easily penetrates into cracks in the column-beam joint 1 without leaking to the outside.

If the inner layer 23 is made of a material that breaks in the event of an earthquake of a certain magnitude or greater, and the repair material 13 is placed inside the inner layer 23 or between the inner layer 23 and the outer layer 24, the repair material 13 can be held in place more stably.

Next, a self-repairing structure 30 according to the third embodiment will be described with reference to FIG. 5. In the description, the configurations common to the second embodiment will be omitted and the same reference numerals will be used.

The self-repairing structure 30 comprises a column 2, a beam 3, and a repair tool 31 fixed to each of the corners defined by the side of the column 2 and the upper and lower surfaces of the beam 3 connected to the side. FIG. 5 shows the self-repairing structure 30 attached to the side of the column 2 and the upper surface of the beam 3. Repair tools 31 are also provided at other corners not shown. The repair tool 31 comprises a sheet 22 fixed to the corner and a repair material 32 held by the sheet 22. The self-repairing structure 30 according to the third embodiment differs from the second embodiment in that the repair material 32 is held by the sheet 22 in a state where it is separated into two components.

The repair material 32 includes a first component 33 and a second component 34. The first component 33 and the second component 34 are held in the inner layer 23 of the sheet 22 separately from each other. For example, the first component 33 may be water, and the second component 34 may be an inorganic material such as a mixture of cement and fine aggregate, and the two components may be mixed together to form a repair material 32 having fluidity such as mortar. The first component 33 may be a base material having fluidity, and the second component 34 may be a hardener for the base material, and the two components may be mixed together during an earthquake of a predetermined scale or greater to form a repair material 32 that has fluidity and hardens in a predetermined time. The first component 33 having fluidity is contained in a thin film that breaks during an earthquake. The first component 33 having fluidity is arranged in the same position as the repair material 13 of the second embodiment. If the second component 34 has fluidity, it is placed in the same position as the repair material 13 in the second embodiment, and if it does not have fluidity, it is placed in the same position as the first component 33 or further inward than the first component 33.

By separating and storing the repair material 32 into two components, deterioration of the quality of the repair material 32 can be suppressed until an earthquake of a specified magnitude or greater occurs.

Figure 6 shows the self-repairing structure 40 according to the fourth embodiment. In the description, the components common to the third embodiment are given the same reference numerals and the description is omitted. In the self-repairing structure 30 according to the third embodiment, the first component 33 and the second component 34 of the repair material 32 are each collected in one place in each repair tool 31 (see Figure 5), but in the self-repairing structure 40 according to the fourth embodiment, the first component 33 and the second component 34 of the repair material 32 are each held in multiple places in the inner layer 23 of the sheet 22 in each repair tool 31. Therefore, in the event of an earthquake of a certain scale or greater, the first component 33 and the second component 34 tend to mix with each other.

The self-repairing structure 50 according to the fifth embodiment will be described with reference to FIG. 7. In the description, the components common to the first to fourth embodiments will be given the same reference numerals and will not be described again. In addition to the components of the self-repairing structures 10, 20, 30, and 40 according to the first to fourth embodiments, the self-repairing structure 50 further includes a steel plate 51 attached to the side of the column 2 and the upper or lower surface of the beam 3 at each corner so as to cover the repair tool 11, 21, and 31.

The plate 51 is L-shaped in side view and includes a vertical portion 52 attached along the side of the column 2 and a horizontal portion 53 attached to the upper or lower surface of the beam 3 and having a length shorter than the vertical length of the vertical portion 52 in the extension direction of the beam 3. The plate 51 is fixed to the column 2 and the beam 3 by anchor bolts 54, but may also be fixed to the column 2 and the beam 3 by other fixing means such as adhesive.

Because the vertical portion 52 is longer than the horizontal portion 53, the bending strength of the column 2 is greater than that of the beam 3. In other words, the column-beam strength ratio is increased. As a result, beam yield failure is more likely to occur than joint yield failure, and failure of the column-beam joint 1 is suppressed. Note that even if the bending strength of the beam 3 is reduced, the column-beam strength ratio increases, but in this case, the strength of the entire building is reduced. In the self-repairing structure 50 of the fifth embodiment, the bending strength of the beam 3 is not reduced, so a decrease in the strength of the entire building can be prevented. A structure in which the repair tools 11, 21, and 31 are removed from the self-repairing structure 50 of the fifth embodiment can be used as a reinforcement structure that changes the failure mode of the existing column-beam joint 1 from joint yield failure (see FIG. 8(A)) to bending yield failure (FIG. 8(B)).

Although the specific embodiments have been described above, the present invention is not limited to the above embodiments and can be modified in a wide range of ways. The column-beam joint, columns and/or beams may be prestressed concrete. The repair material separated into two components in the third or fourth embodiment may be applied to the first embodiment.

1: Column-beam joint 2: Column 3: Beam 10, 20, 30, 40, 50: Self-repairing structure 11, 21, 31: Repair tool 12, 22: Sheet 13, 32: Repair material 33: First component 34: Second component 51: Plate 52: Vertical portion 53: Horizontal portion

Claims (6)

Concrete pillars and
A concrete beam joined to the column;
a repair tool fixed to each of the corners defined by a side surface of the column and an upper surface and a lower surface of the beam connected to the side surface;
Each of the repair tools includes:
A sheet fixed to the side surface of the column and the upper surface or the lower surface of the beam;
A repair material having flowability and held in a sealed state in the sheet ,
A self-repair structure for a column-beam joint , characterized in that the repair material is configured to escape from the sealed state in the event of an earthquake of a specified magnitude or greater and to harden within a specified period of time. The self-repair structure of a beam-column joint as described in claim 1, characterized in that the sheet includes an inner layer and an outer layer that does not allow the repair material to pass through, and the repair material is held inside the outer layer. The self-repairing structure of a beam-column joint as described in claim 2, characterized in that the inner layer is made of a material that breaks in the event of an earthquake of a predetermined magnitude or greater, the outer layer is made of a material that is more elastic than the inner layer, and the repair material is placed inside the inner layer or between the inner layer and the outer layer. The self-repair structure for a beam-column joint described in any one of claims 1 to 3, characterized in that the repair material includes a first component and a second component that are held separately from each other in the sheet. Concrete pillars and
A concrete beam joined to the column;
a repair tool fixed to each of the corners defined by a side surface of the column and an upper surface and a lower surface of the beam connected to the side surface;
Each of the repair tools includes:
A sheet fixed to the side surface of the column and the upper surface or the lower surface of the beam;
A repair material having flowability and held by the sheet,
the repair material includes a first component and a second component that are held separate from one another in the sheet;
A self-repair structure for a beam-column joint, characterized in that the first component and the second component are water and an inorganic material, or a base agent and a hardener for the base agent. Concrete pillars and
A concrete beam joined to the column;
a repair tool fixed to each of the corners defined by a side surface of the column and an upper surface and a lower surface of the beam connected to the side surface;
Each of the repair tools includes:
A sheet fixed to the side surface of the column and the upper surface or the lower surface of the beam;
A repair material having flowability and held by the sheet,
At each of the corners, a plate is attached to the side of the column and the upper surface or the lower surface of the beam so as to cover the repair tool;
A self-repairing structure for a column-beam joint, characterized in that the plate includes a vertical portion attached along the side of the column, and a horizontal portion attached to the upper or lower surface of the beam and having a length shorter than the up-down length of the vertical portion in the extension direction of the beam.

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