JP2003328566A - Concrete block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete block capable of inexpensively and effectively reinforcing an existing column against an earthquake by enhancing shear rigidity without excessively increasing flexural rigidity of the existing column. <P>SOLUTION: In the concrete block, arced direction both ends of an arced face of a top face 14 facing a bottom face 11 comprising a plane of a parallelogram form side faces 13a and 13b comprise planes. A plurality of grooves 15 are formed along an arc of the arced face of the top face 14, the grooves form upper and lower edges of the parallelogram as seen from above, and they are extended in parallel with upper and lower side faces 12a and 12b. A distance between an upper end of a left edge and a leg of a perpendicular line extended down from an upper end of a right edge of the parallelogram is smaller than one-fourth of a pitch of the grooves 15 for a pitch equivalent to one of gaps formed in four corners of the existing column. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete block used for reinforcing existing columns in a reinforced concrete structure against earthquakes and the like.

[0002]

2. Description of the Related Art Conventionally, as this type of concrete block, for example, one shown in FIG. 8 has been known (Japanese Patent Publication No. 53-16214). As shown in FIG. 8 (B), this concrete block has a bottom surface 51a consisting of a rectangular flat surface and an upper surface 51b consisting of a quarter arc surface of a circle having the bottom surface as a chord and centering on the axis of the existing column. And two side surfaces 51c consisting of a crescent-shaped plane adjacent to the top and bottom of the bottom surface.
It is a PC board 51 composed of.

As shown in FIG. 8 (A), the reinforcement of the existing pillar is as follows.
The PC plate 51 is adhered to the four peripheral surfaces of an existing column 52 made of reinforced concrete having a square cross section over substantially the entire length with cement paste or the like, and a PC steel wire 53 is spirally formed around the PC plate 51 while applying a constant tension force. After being wound and integrated, a surface finish 54 is applied to the entire circumference of the existing column 52 covered with the PC plate 51.

[0004]

It is stated that the above-mentioned method of reinforcing existing columns is to prevent the shear failure of the existing columns 51 due to the repeated load applied by an earthquake by effectively restraining the core concrete. However, in the above-described conventional method of reinforcing an existing column, the four peripheral surfaces of the existing column 52 are covered with the PC plate 51 of an integral body over substantially the entire length, and the periphery thereof is covered with P.
Since it is fastened with the C steel wire 53, the bending rigidity of the reinforcing column becomes too large, and the deformability and energy absorbing capacity of the reinforcing column decrease, resulting in the problem that the earthquake resistance of the reinforcing column is not improved.

Further, since the PC steel wire 53 is wound around the PC plate 51 while applying a constant tension force, the PC steel wire 53 is directed in a tangential direction which constantly changes as the circular cross section of the reinforcing column is wound. There is also a problem that a device such as a hydraulic cylinder is indispensable because it is necessary to pull the lever, which cannot be done manually. Further, since the surface of the PC plate 51 is flat, the wound PC steel wire 53 may be displaced, the reinforcement may be incomplete, or the mortar 4 should be applied to the entire circumference to prevent the deviation. However, there is a problem that the construction is troublesome and expensive.

[0006] Therefore, an object of the present invention is to easily and inexpensively perform seismic proofing of existing columns by devising a concrete block having a size and shape capable of increasing shear strength while suppressing an increase in bending rigidity of reinforced columns. It is to provide a concrete block that can be reinforced.

[0007]

In order to achieve the above object, a concrete block according to the invention of claim 1 has a bottom surface composed of parallelogrammic planes, four side surfaces composed of planes adjacent to the bottom surface, and It is characterized in that it has an upper surface facing the bottom surface and having an arc surface continuing to the side surface.

Unlike the PC board described in the conventional example of FIG. 8 (B), the concrete block has a circular arc direction (left-right direction) of an arc surface of an upper surface facing a bottom surface formed of a parallelogram plane.
Both ends are flat side surfaces. Therefore, when this concrete block is attached to each peripheral surface of an existing column having a regular polygonal cross section with, for example, cement paste, a gap is formed between the side surfaces facing each other at each corner of the regular polygon. Further, by shortening the length of the side surface in the plan view of the concrete block, preferably shorter than the length of one side of the existing pillar, if you stack a plurality of concrete blocks to cover the entire length of each peripheral surface of the existing pillar, A circular gap is created in the stacking area. Then, a steel wire is wound around the outer peripheral surface of this concrete block. For existing columns reinforced with concrete blocks all around, the above-mentioned gap changes when an earthquake load is applied, so the shear strength is increased without increasing the bending rigidity against the earthquake load compared to the conventional example, The ability to absorb seismic energy can be increased. That is, according to the concrete block and the steel wire, it is possible to firmly reinforce the existing column against repeated horizontal loads due to an earthquake. In addition, in the conventional example of FIG. 8 (B), when the existing columns are pasted around the entire circumference as shown in FIG. 8 (A), adjacent concrete blocks are in contact with each other without a gap, and the contact point is the existing one due to the earthquake. Although there is a possibility that the pillar will be chipped off due to deformation, the concrete block of the present invention does not have such a possibility.

A concrete block according to claim 2 is
A feature is that a plurality of parallel grooves are formed on the upper surface of the concrete block.

The concrete block has a plurality of grooves formed along an arc forming an arc surface, and these grooves extend parallel to the upper and lower sides of a parallelogram in a plan view, for example. Therefore, concrete blocks are sequentially spirally formed on each peripheral surface of the existing pillar having a regular polygonal cross section so that, for example, if one of these grooves goes through the gaps at the corners of the existing pillar in the circumferential direction and goes around once, the groove advances by one pitch. If pasted, a steel wire that has been processed into a spiral shape with a diameter slightly smaller than the diameter of the spiral groove in advance can be easily wound around the groove with a small force, for example, even manually, and the wound steel wire is ,
Unlike the conventional example, the concrete block does not slip even if the surface is not coated with mortar, and the concrete block is firmly integrated with the existing column to greatly improve the shear strength of the existing column. Therefore, according to the concrete block of the above-described embodiment, it is possible to increase the shear resistance against repeated horizontal load due to an earthquake and firmly reinforce the existing column, and it is possible to significantly reduce the labor and cost required for reinforcement. .

A concrete block according to claim 3 is
The plurality of grooves form part of a spiral.

[0012] In the concrete block, grooves provided in parallel with each other on an arcuate surface as an upper surface form a part of a spiral. Therefore, if concrete blocks are sequentially attached to each peripheral surface of an existing pillar with a regular polygonal cross section so that these grooves are continuous in the circumferential direction through the gaps at the corners of the existing pillar, the existing pillar will rise while surrounding it. One spiral groove is formed, and a steel wire previously processed into a spiral shape can be fitted into this spiral groove and easily wound. That is,
Also in the invention of claim 3, it is possible to increase the shear resistance against repeated horizontal load due to an earthquake and to firmly reinforce the existing column, and also to significantly reduce the cost and labor required for the reinforcement.

A concrete block according to claim 4 is
The bottom surface and the top surface form a parallelogram in a projection view from the normal direction of the bottom surface, and a perpendicular line drawn from one end of the pair of sides in the direction intersecting with the groove direction of the parallelogram to the other side. The distance between the foot and the one end of the other side is
It is characterized in that it is smaller than 1/4 of the pitch of the grooves.

A concrete block according to claim 4 is
For example, the distance between the leg of a perpendicular line drawn from the upper end of the right side to the left side of the parallelogram in the plan view and the upper end of the left side is smaller than ¼ of the groove pitch. Specifically, the groove pitch is 1
The pitch is smaller than / 4 by the pitch corresponding to the height of the side surfaces forming the left and right sides in the plan view, that is, the pitch corresponding to one of the gaps formed at the four corners of the existing pillar having a square cross section. Therefore, if the concrete blocks are sequentially attached in a spiral shape to the four circumferential surfaces of the existing pillar having a square cross section, the above grooves are smoothly spirally connected through the gaps at the four corners, and in the same manner as described above, A steel wire that has been processed into a spiral shape in advance can be easily wound manually, and the steel wire does not move without surface finishing unlike the conventional example, and the concrete block is firmly integrated with the existing column.

That is, according to the concrete block of claim 4, the existing column having a square cross section can be strongly reinforced against repeated horizontal loads due to an earthquake, and the labor and cost required for the reinforcement can be significantly reduced. You can In addition, in the plan view of the concrete block, the distance between the upper edge of the left side and the foot of the perpendicular line drawn from the upper edge of the right side of the parallelogram to the left side is 1 / n (n: an integer of 3 or more) of the groove. For example, the same seismic reinforcement as above can be applied to an existing column having a regular n-gonal cross section.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a perspective view showing an example of a concrete block used to reinforce an existing column, and FIGS. 2 (A) to 2 (E) are a plan view, an upper side view, and a bottom view, respectively, of the concrete block of FIG. It is a side view, a right side view, and a left side view. The concrete block 1 is shown in FIG.
A bottom surface 11 formed by a parallelogram-shaped plane as shown in FIG. 2 and a plane adjacent to the bottom surface 11, the upper and lower side surfaces of which are cut off at both ends as shown in FIGS. 2 (B) and 2 (C). 12a,
12b and four side surfaces basically consisting of rectangular left and right side surfaces 13a and 13b, as shown in FIGS. 2D and 2E, and the left and right side surfaces 13a facing and facing the bottom surface 11. ,
It is composed of an upper surface 14 which is an arcuate surface continuous with 13b.
The upper surface 14 of the concrete block 1 has upper and lower side surfaces 1.
2a and 12b form a plurality of arcuate grooves 15 as shown in FIG. 1 which extend in parallel with the lower side and in parallel with each other in the plan view of FIG. 2 (A). In FIG. 1, the broken line indicates the bottom of the groove 15, and the solid line between the broken lines indicates the peaks between the adjacent grooves.

FIGS. 3 and 4 are a vertical sectional view and a plan view showing a state in which the concrete block 1 is attached to and reinforced by the four circumferential surfaces of an existing column 20 having a square cross section. In the concrete block 1, the widths of the left and right side surfaces 13a, 13b are smaller than the width of the existing columns 20, and the upper and lower side surfaces 12a,
The height of 12b is also smaller than the width of the existing column 20.
This concrete block is sequentially pasted in the circumferential direction while adhering the bottom surface 11 to the lower circumferential surface 21 of the existing pillar 20 with cement paste, and then is already pasted through the spacing portion 22 filled with the poorly mixed mortar 23 and the like. The blocks are stacked on top of each other, and similarly, they are sequentially attached to the peripheral surface 21 of the existing column 20 in the circumferential direction in order to cover the outer periphery of the existing column 20 in a spiral shape from the base portion 20a upward. However, the upper and lower ends of the existing pillar 20 are
It is not covered with concrete block 1 so that it can be flexibly flexed under earthquake load while suppressing the increase in bending rigidity of the reinforcement column.
(See Figure 3). The member sandwiched between the upper and lower concrete blocks is not limited to the poorly mixed mortar 23, and a material such as a wood plug or rubber that is damaged and opened by a predetermined earthquake load can be used.

As shown in FIG. 4, the concrete block 1 has an arc surface 14 which is an upper surface when the existing pillar 20 is covered.
Is a cylindrical surface with a constant radius centered on the axis C of the existing column, and both ends of the arc surface 14 are cut off to form left and right side faces 13a, 13b.
On both sides of 20b, 20c, 20d, there is a gap where the peripheral surface 21 of the existing column is exposed. Due to the existence of this gap, it is possible to directly observe the degree of damage to the existing column after the earthquake load is applied. Top 1 of concrete block 1
4 are parallel to the upper and lower side surfaces 12a and 12b, and the plurality of grooves 15 are provided in parallel to each other. When the concrete block covers the four circumferential surfaces of the existing pillar as shown in FIG. Grooves 15 of concrete blocks adjacent to each other in the circumferential direction
And smoothly spiral.

FIG. 5 is a development view showing the groove 15 of the concrete block 1 covering the four circumferential surfaces 21 of the existing columns 20 and the spiral steel wire 24 fitted and wound in the groove. As shown in the left end of FIG. 5, the groove 15 is formed by forming a sinusoidal concave portion on the upper surface 14 of the concrete block 1, and starts from the lower end of the concrete block attached to the lower part of the first peripheral surface 21a, and is already installed. After passing through the gaps between the corners 20a, 20b, 20c, 20d of the pillar 20, the grooves 15 of the three concrete blocks attached to the peripheral surfaces 21b, 21c, 21d on the right side in sequence are connected, and after going around the existing pillar again, The concrete block on the peripheral surface 21a (which overlaps with the right end of FIG. 5 and shows a part of the concrete block) is connected to one groove above, and this is repeated to reach the upper end of the existing column. A steel wire 24 is wound around the spiral groove 15 as illustrated.

The upper and lower sides 12a, 12b of the concrete block 1, which are shown as the upper and lower sides of the parallelogram in FIG. 5, and thus the grooves 15 extending parallel to this, are the four of the existing columns, as can be seen in FIG. When the peripheral surfaces 21a to 21d are rotated once, the groove 15 is raised by a distance of one pitch p. Speaking of one groove 15 (for example, the lower end of the peripheral surface 21a) that traverses the concrete block 1, the ascending distance of the groove is 1/4 of that of the existing columns.
Column angles 20a, 20b, 20c, 20d from p / 4 corresponding to the circumference
Is a value obtained by subtracting α from the amount of rise corresponding to the interval (p / 4−α), and therefore the upper and lower side surfaces 12 of the concrete block 1
As shown in FIG. 2 (A), the inclinations of a and 12b are such that the distance between the lower end of the right side 13b and the foot of a perpendicular line drawn from the lower end of the left side 13a of the left and right sides of the parallelogram to the right side 13b is ( p / 4-
The inclination becomes α). The ascending amount α corresponding to the above-mentioned clearance is the column angles 20a, 20b, 20c, 20d in FIG.
This is the ascending distance when the groove 15 advances through the gap between and with the same inclination as in the concrete block 1.

The steel wire 24 wound around the groove 15 is shown in FIG.
Unlike the linear shape of the conventional example, a spiral shape having a diameter smaller than the diameter of the groove 15 that makes one turn around the existing column 20 (preferably a diameter of 80% of the diameter having the diagonal line of the cross section of the existing column). It is pre-processed into a bundle and is manually wound without using a tensioning machine such as a hydraulic cylinder. The method of winding the steel wire 24 bundled in a spiral shape around the existing column is described in detail in Japanese Patent No. 149647 assigned to the applicant of the present application, and therefore, only a brief description will be given here.

That is, the steel wire 24 processed into a spiral bundle is arranged vertically so that the loop surface of the bundle is parallel to the peripheral surface of the existing column, and the start end 24a is bent at a right angle to start winding.
(See Fig. 5) Insert it into a hole (not shown) provided at the lower end of the peripheral surface 21a, fix it, and rotate the bundle of steel wires around the existing pillar while rotating it in the direction that can be unraveled. The steel wire 24 is wound around the existing column, fitted into the spiral groove 15, and sequentially wound up. Finally, the end 24b bent at a right angle (see FIG. 4) is inserted into a hole provided at the upper end of the peripheral surface and fixed, and the winding is completed. As a method of fixing the steel wire end portion, instead of fixing the steel wire to the peripheral surface of the existing column, the steel wire may be overlapped and wound around the outer periphery of the concrete block, and the overlapped portion may be fixed with a clip. This method
Instead of bending the spiral bundle of steel wire in the loop plane in the direction that unwinds the loop to open it wide, instead of twisting the spiral bundle of steel wire around the existing column, twist the steel wire slightly around its axis. Since the winding can be performed within the elastic deformation range of just twisting, a large-scale machine such as the hydraulic cylinder described in the conventional example of FIG. 8 is not required, and the work can be performed easily and quickly with only human power. The steel wire may be a steel bar or a stranded wire.

A method of reinforcing the existing columns 20 using the concrete block 1 of the above embodiment will be described below. First, a poor mixture mortar 23 is applied to the foundation 20a at the lower end of the existing pillar 20 with a predetermined thickness, and the cement paste 22 is applied to at least one of the four circumferential surfaces 21 of the existing pillar 20 and the bottom surface 11 of the concrete block 1. After the application, the bottom surface 12b of the concrete block 1 is placed on the poorly mixed mortar 23, and the bottom surface 11 is brought into contact with each peripheral surface 21 to form four concrete blocks 1 on the outer circumference of the existing pillar 20.
Stick. Next, a thickness of 1 to 2 in which the poor mixture mortar 23 is filled on the upper surface of each concrete block that is pasted
A space 22 of cm is provided, and four concrete blocks 1 are stacked on the space 22 and attached to each peripheral surface 21 in the same manner. Here, as shown in FIG. 5, the concrete block 1 is a parallelogram in which the left, right and upper and lower sides are not orthogonal to each other, so that the upper surface of the poor mixing mortar 23 at the lower end and the poor mixing mortar 23 between the upper and lower blocks are filled. The separated portion 22 is
It is tilted with respect to the horizontal plane.

When the concrete block 1 has been attached over the entire length of the four circumferences of the existing columns 20, the area around the existing columns is reduced to 1
The steel wire 24, which is pre-processed into a spiral bundle having a diameter slightly smaller than the diameter of the spiral groove 15 of the surrounding concrete block, is fitted into the spiral groove 15 by the manual method as described above, and the whole concrete is The winding around the block is completed. This steel wire winding method has a great advantage that it does not require a large-scale machine such as a hydraulic cylinder as described above, and can be installed easily and quickly by only human power. In addition,
The upper and lower ends of the existing column are not covered with the concrete block 1 because the bending rigidity described above is not increased. Further, since the wound steel wire 24 is closely fitted in the groove 15 and is not displaced, it is not necessary to apply mortar to the entire surface of the steel wire as in the conventional example of FIG. Steel wire 24
As described in FIGS. 4 and 5, the start end 24a and the end end 24b of the column are fixed by inserting them into the holes provided on the peripheral surface of the existing column.
Instead of this, the steel wires may be fixed by binding them with a binding wire or the like.

The existing columns 20 shown in FIGS. 3 and 4 reinforced in this way behave in the following manner during an earthquake and effectively absorb the vibration energy of the earthquake. The existing pillars 20 do not have the vertically long and integral four PC plates 51 attached to the four peripheral surfaces as in the conventional example described with reference to FIG. A brittle material such as 23 or a wooden plug is sandwiched and piled up to be attached and reinforced, and a gap is formed in which the peripheral surfaces of the corners 20a, 20b, 20c, and 20d of the existing column 20 are exposed. Therefore, when a bending load due to an earthquake is applied, the existing columns 20 are broken and opened by the poorly mixed mortar 23 in the stacking portion of the block, and are deformed as shown in FIG. 6 before an excessive bending load is applied. That is, unlike the conventional example shown in FIG. 8, the reinforcing column of the present embodiment does not have excessively high bending rigidity to reduce the deformability and energy absorbing ability, and as a result, the earthquake resistance is improved. Further, since the concrete blocks adjacent to each other in the circumferential direction do not contact each other due to the gap 22, the contact points do not collide with each other due to the deformation of the existing columns due to the earthquake and fall off.

The existing column 20 has a steel wire 24 which is pre-processed into a spiral shape having a diameter slightly smaller than the diameter of the spiral groove 15.
Since the steel wire 24 adheres to the concrete block 1 due to the elastic force and is wound while expanding the diameter while slightly twisting it without using a hydraulic cylinder or the like,
4 significantly improves the shear strength of the existing column 20. That is, the reinforcing column of the present embodiment has increased shear strength without excessive bending rigidity, resulting in improved toughness and effective absorption of seismic energy to strengthen the existing column 20. It can be reinforced.

FIG. 7 is a sectional view showing another embodiment of the concrete block of the present invention. This concrete block 31 reinforces the existing column 20 having the same square cross section as in FIG. 4, but the radius of curvature of the arc surface of the upper surface 34 is
The only difference is that the radius of curvature is larger than the radius of curvature of the circular arc surface 14 circumscribing the existing column in FIG. The method of reinforcing the existing column using the concrete block 31 of this embodiment is essentially the same as the method described in the previous embodiment, and a description thereof will be omitted.
Has the same action and effect.

In the above embodiment, the upper and lower side surfaces 12a and 12b which are the upper and lower sides of the parallelogram in the plan view of the concrete block 1 are the left and right side surfaces 13a and 1b.
The case where it is not orthogonal to 3b has been described. However, according to the present invention, as long as the plurality of arc-shaped grooves 15 are provided so as to form a part of the spiral as described in claim 3, a parallelogram having upper and lower side surfaces and right and left side surfaces orthogonal to each other It can also be applied to a rectangular concrete block in the figure, and the same action and effect are exhibited.

Further, the inclination of the groove 15 is equivalent to one of the four corner gaps in which the height with respect to the horizontal distance is 1/4 of the groove pitch p in the concrete block 1 used for the existing column 20 having a square cross section. However, if the pitch is smaller than 1 / n of the groove pitch p by one pitch corresponding to one of the n-corner gaps, a spiral shape is formed around the existing column having a regular n-gonal cross section. It can be a surrounding one. The groove 15 of the above-described embodiment is a single-row groove that advances one pitch per revolution, but it may be a two-row groove that advances two pitches per revolution.
The cross-sectional shape of the groove is not limited to the sinusoidal shape of the embodiment, and the cross-sectional shape of the groove may be trapezoidal, for example.

Further, in the concrete block of the present invention, by changing the circumferential width and the radius of curvature of the circular arc surface so as to match the existing column cross-sectional shape, a rectangular cross section or an n-gonal cross section in which each side is not equal in length. It can also be applied to existing columns, and the same operation as described in the above-mentioned embodiment,
It is possible to exert an effect.

[0031]

As is apparent from the above description, in the concrete block according to claim 1 of the present invention, the dimension between both ends in the arc direction of the arc surface of the upper surface facing the bottom surface formed by the plane of the parallelogram is already established. Since it is shorter than one side of the column and has a side surface consisting of a flat surface, stacking and sticking it on each peripheral surface of an existing column with a regular polygonal cross-section, to the corner and stacking part of the regular polygon. It is possible to cover the entire circumference of the existing pillar with a gap. Therefore, when a steel wire is wound around the outer circumference of the concrete block, the reinforcing column breaks and changes during bending deformation, so the bending stiffness against earthquake load does not increase excessively as in the conventional example, and shearing occurs. The proof stress can be increased to enhance the ability to absorb seismic energy, and the existing columns can be strongly reinforced against repeated loads due to the earthquake, and the gaps between the concrete blocks adjacent in the circumferential direction cause the blocks to collide with each other. It can prevent it from falling off.

A concrete block according to claim 2 is
A plurality of grooves parallel to each other are formed on the upper surface of the concrete block which is an arc surface, and these grooves extend in parallel with the upper and lower sides of the concrete block, for example, forming a parallelogram in a plan view. Therefore, the concrete block is sequentially spirally formed on each peripheral surface of the existing pillar having a regular polygonal cross section so that, for example, the groove advances by one pitch when the groove makes one round in a row in the circumferential direction through the gaps at the corners of the existing pillar. If pasted, a steel wire processed in advance into a spiral shape having a diameter slightly smaller than the diameter of this spiral groove can be easily wound around the groove with a small amount of human power, and the wound steel wire is a conventional example. Even if you do not apply mortar to the surface like the above, you can firmly integrate the concrete block into the existing column and greatly improve the shear strength of the existing column,
In addition, the labor and cost required for reinforcement can be significantly reduced.

A concrete block according to claim 3 is
Grooves provided in parallel with each other on the circular arc surface that is the upper surface of the concrete block form a part of the spiral. Therefore, if concrete blocks are stacked and laminated on each peripheral surface of an existing pillar having a regular polygonal cross section so that these grooves are continuous in the circumferential direction through the gaps at the corners of the existing pillar, the concrete block will be flat. Even if it is rectangular in the figure, one spiral groove that rises while surrounding the existing column is formed, and a steel wire processed in advance in a spiral shape can be fitted into this spiral groove with a small amount of human power and easily wound. , It is possible to strengthen the existing column by strengthening the shear strength against repeated load due to an earthquake, and it is possible to significantly reduce the cost and labor required for the reinforcement.

A concrete block according to claim 4 is
For example, the distance between the leg of a perpendicular line drawn from the upper end of the right side to the left side of the parallelogram in the plan view and the upper end of the left side is smaller than ¼ of the groove pitch. Therefore, if concrete blocks are sequentially attached to the four circumferential surfaces of an existing column having a square cross section in a spiral shape, the above-mentioned grooves will be smoothly connected in a spiral shape through the gaps at the four corners. The steel wire processed into a spiral shape can be easily wound manually, and the steel wire does not move without surface finishing unlike the conventional example, increasing the shear resistance against earthquakes and reinforcing the existing columns firmly Therefore, the labor and cost required for reinforcement can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a concrete block of the present invention used for reinforcing existing columns.

FIG. 2 is a bottom view, top and bottom side views, and left and right side views of the concrete block.

3 is a vertical cross-sectional view of an existing column reinforced with the concrete block of FIG.

FIG. 4 is a plan view of an existing column shown in FIG.

5 is a development view of the groove of the concrete block of FIGS. 3 and 4 and the spiral steel wire fitted and wound in the groove. FIG.

FIG. 6 is a front view showing how the existing column is deformed by an earthquake load.

FIG. 7 is a plan view showing another embodiment of the concrete block of the present invention.

FIG. 8 is a perspective view showing a conventional method of reinforcing an existing column with a PC plate.

[Explanation of symbols]

1,31 concrete block 11 Bottom 12a, 12b upper and lower sides 13a, 13b Left, right side 14,34 upper surface 15 grooves 20 existing columns 21 circumference 22 Separation part 23 Poor mixed mortar 24,35 steel wire

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshifumi Matsuda             2-4-24 Shibata, Kita-ku, Osaka-shi, Osaka             Within Japan Passenger Railway Co., Ltd. (72) Inventor Masao Kitago             193, 6th town north of Azalea Hill, Nabari City, Mie Prefecture (72) Inventor Terukazu Shibata             2-2-2 Matsuzaki-cho, Abeno-ku, Osaka-shi, Osaka             No. Okumura Gumi Co., Ltd. (72) Inventor Shin Shigeno             2-2-2 Matsuzaki-cho, Abeno-ku, Osaka-shi, Osaka             No. Okumura Gumi Co., Ltd. F-term (reference) 2E176 AA01 BB29

Claims (4)

[Claims] 1. A bottom surface formed of a parallelogrammic plane, four side surfaces formed of a plane adjacent to the bottom surface, and an upper surface formed of an arc surface facing the bottom surface and connected to the side surfaces. And concrete blocks. 2. The concrete block according to claim 1, wherein a plurality of grooves parallel to each other are formed on the upper surface. 3. The concrete block according to claim 2, wherein the plurality of grooves form part of a spiral. 4. The concrete block according to claim 2, wherein the bottom surface and the top surface form a parallelogram in a projection view from a normal direction of the bottom surface, and a direction parallel to a direction of the groove of the parallelogram. A concrete block characterized in that a distance between a foot of a perpendicular line drawn from one end of the pair of sides to the other side and one end of the other side is smaller than ¼ of the pitch of the grooves.