JP2012026228A - Crack-inducing joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack-inducing joint capable of being attached without increasing the thickness of a concrete structure by the thickness of a protrusively-constructed portion, transmitting shear stress along a joint material and sufficiently exerting structural performance.SOLUTION: Crack-inducing joints 1 and 10 are provided to generate cracks in a concrete structure 2 according to a plan. The crack-inducing joints 1 and 10 comprise a material having a compression strength equal to or more than that of the concrete 3 of the concrete structure 2, and are embedded inside the concrete 3 so that end parts 5 and 12 are in contact with the surface of the concrete structure 2. The end parts 5 and 12 are linearly formed, and embedded parts 4 and 11 have a shape recessed and projected in a direction crossing the generating direction of shear stress.

Description

  The present invention relates to a crack-inducing joint provided for intentionally generating cracks in a concrete structure.

  In general, concrete structures such as reinforced concrete seismic walls are prone to cracking due to temperature changes caused by the heat of hydration and outside air temperature of the cement, and shrinkage due to drying, and this cracking is completely avoided. It is not possible. For this reason, crack-inducing joints are installed in the concrete structure at predetermined intervals so that cracks are generated systematically so that the aesthetic appearance is not impaired.

  Conventionally, for example, as shown in FIG. 12, the thickness tw ′ of the bulge portion 21 is added to the thickness tw of the earthquake resistant wall 20, and a groove-shaped crack-inducing joint 22 is provided in the burial portion 21 to secure a cross-sectional defect. A technique for inducing a crack is known (for example, see Patent Document 1).

  Further, as described above, in addition to securing the cross-sectional defect by providing the groove-shaped crack-inducing joint 22 in the flared portion 21, as shown in FIG. 13, a pipe 23 is embedded as a joint material inside the earthquake-resistant wall 20. For example, as shown in FIG. 14, an iron plate 24 is embedded as a joint material in the earthquake-resistant wall 20 (see, for example, Patent Document 3).

JP 2007-56521 A JP 2008-82126 A JP 2005-179889 A

  However, in any of the above-described conventional techniques, it is necessary to provide a groove-like crack-inducing joint 22 in the upper portion 21 in order to generate a crack in a straight line on the surface of the earthquake-resistant wall 20 aesthetically. For this reason, the thickness tw of the earthquake resistant wall 20 is increased by the thickness tw 'of the knitted portion 21, the concrete amount increases, the weight increases, and the effective area in the building facing the earthquake resistant wall 20 decreases.

  Further, since the actual thickness of the earthquake-resistant wall 20 becomes thicker than the wall thickness in the structural calculation, the rigidity is higher than the design, and the rigidity ratio and eccentricity of the building change, which may have a structural adverse effect.

  Furthermore, when the iron plate 24 is embedded as a joint material inside the earthquake-resistant wall 20, the joint material is smooth and shear stress cannot be transmitted along the joint material, so that the structural performance as the earthquake-resistant wall 20 is sufficient. There was also a problem that it could not be demonstrated.

  The present invention has been made to solve the above-described problems, and can be attached without increasing the thickness of the concrete structure by the thickness of the wiping portion, and enables transmission of shear stress along the joint material, An object of the present invention is to provide a crack-inducing joint that can sufficiently exhibit structural performance.

  In order to achieve the above-mentioned object, the present invention is a crack-inducing joint provided for generating cracks in a concrete structure in a planned manner, and is made of a material having a compressive strength equal to or higher than that of the concrete of the concrete structure. And is embedded in the concrete so that the end portion is in contact with the surface of the concrete structure, the end portion is formed in a straight line, and the embedded portion is in a direction in which the shear stress of the concrete is generated. It has a shape that is uneven in the intersecting direction.

  Moreover, it is preferable that the flange part is formed in the said edge part of the crack induction joint which concerns on this invention so that the surface of the said concrete structure may be touched.

  According to the crack-inducing joint according to the present invention, the thickness of the concrete structure can be attached without increasing the thickness of the wiping portion, and the shear stress along the joint material can be transmitted to sufficiently exhibit the structural performance. Various excellent effects can be obtained.

It is sectional drawing which shows the state which attached the crack induction joint which concerns on the 1st Embodiment of this invention to the earthquake-resistant wall. It is a front view which shows the state which attached the crack induction joint concerning the 1st Embodiment of this invention to the earthquake-resistant wall. It is an AA arrow line view of FIG. It is a perspective view which shows the crack induction joint which concerns on the 1st Embodiment of this invention. (A), (b), (c) is sectional drawing which shows the modification of the crack induction joint which concerns on the 1st Embodiment of this invention, respectively. It is sectional drawing which shows the state which attached the crack induction joint which concerns on the 1st Embodiment of this invention to the earthquake-resistant wall. It is a perspective view which shows the state which attached the crack induction joint which concerns on the 2nd Embodiment of this invention to the earthquake-resistant wall. It is a front view which shows the state which attached the crack induction joint which concerns on the 2nd Embodiment of this invention to the earthquake-resistant wall. (A) is a top view which shows the modification of the crack induction joint concerning the 2nd Embodiment of this invention, (b) is the perspective view. (A) is a top view which shows another modification of the crack induction joint which concerns on the 2nd Embodiment of this invention, (b) is another another of the crack induction joint which concerns on the 2nd Embodiment of this invention. It is a top view which shows a modification. It is sectional drawing which shows the state which attached the crack induction joint which concerns on the 2nd Embodiment of this invention to the earthquake-resistant wall. It is sectional drawing which shows the state which provided the conventional crack induction joint in the earthquake-resistant wall. It is sectional drawing which shows the state which provided another conventional crack induction joint in the earthquake-resistant wall. It is sectional drawing which shows the state which provided the conventional another crack induction joint in the earthquake-resistant wall.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the crack induction joint according to the first embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a sectional view showing a state in which the crack-inducing joint according to the first embodiment of the present invention is attached to the earthquake-resistant wall, and FIG. 2 shows the crack-inducing joint according to the first embodiment of the present invention. FIG. 3 is a front view showing a state of being attached to the earthquake-resistant wall, FIG. 3 is a view taken along the line AA in FIG. 1, FIG. 4 is a perspective view showing a crack-inducing joint according to the first embodiment of the present invention, and FIG. (a), (b), (c) is a sectional view showing a modification of the crack inducing joint according to the first embodiment of the present invention, and FIG. 6 is a crack inducing according to the first embodiment of the present invention. It is sectional drawing which shows the state which attached the joint to the earthquake-resistant wall.

  As shown in FIG. 1, the crack-inducing joint 1 according to the present embodiment is embedded in the surface portions on both sides of the reinforced concrete seismic wall 2 at a predetermined interval, such as stainless steel or ceramic. It is made of a material having a compressive strength equal to or higher than that of the concrete 3 of the reinforced concrete seismic wall 2. The crack-inducing joint 1 includes an embedded portion 4 embedded in the earthquake-resistant wall 2 and a flange portion 5 formed at an end of the embedded portion 4, and the embedded portion 4 on one side is embedded. The insertion width is formed to be about 10 to 15% of the wall thickness of the earthquake resistant wall 2.

  As can be clearly understood from FIGS. 3 and 4, for example, the embedded portion 4 has a wave shape in a direction intersecting a direction in which a shear stress is generated (arrow direction in FIG. 3) with a strip-shaped plate material having a thickness of about 1 to 2 mm. It has a shape that is bent. The shape of the embedding part 4 is not limited to the shape bent into the above-described waveform. For example, the shape bent in a zigzag as shown in FIG. 5A or the shape shown in FIG. As long as it has an uneven shape in a direction intersecting the shear stress generation direction (arrow direction in FIG. 3), such as a punching metal shape or an expanded metal shape as shown in FIG. It may be a shape.

  As can be clearly understood from FIGS. 2 and 4, the flange portion 5 is embedded in the concrete 3 so as to be in contact with the surface of the earthquake-resistant wall 2, and is formed linearly by a belt-like flat plate. Further, as shown in FIG. 4, nail holes 6 are formed in the flange portion 5 at a predetermined pitch. As a result, when the crack-inducing joint 1 is installed, the flange 5 is brought into contact with the inner surface of the concrete mold (not shown) and the nail is struck against the concrete mold via the nail hole 6, thereby the concrete mold. The crack-inducing joint 1 can be easily fixed to the frame.

  And the crack induction joint 1 which concerns on embodiment of this invention provided with the above-mentioned structure is fixed to the said concrete formwork, concrete is laid, and it embeds in the surface part of the both sides of the earthquake-resistant wall 2 with a predetermined space | interval. Then, as shown in FIG. 6, since stress concentrates on the installation part of the crack induction joint 1 due to the effect of shrinkage due to drying of the concrete, the crack 7 can be induced in this part.

  As described above, according to the crack inducing joint 1 according to the above-described embodiment, it is possible to surely induce a crack along the crack inducing joint 1 without providing a cracked portion. The minimum thickness can be suppressed, the amount of concrete and weight can be reduced, and the effective area in the building facing the seismic wall 2 can be increased.

  In addition, the crack-inducing joint 1 is made of a material having a compressive strength equal to or higher than that of the concrete 3 of the earthquake resistant wall 2 and has unevenness in a direction intersecting with the direction of occurrence of shear stress (arrow direction in FIG. 3). Because it has a shape that can transmit shear stress along the crack-induced joint 1, the structural performance as the seismic wall 2 can be sufficiently exerted, and the durability of the seismic wall 2 can be adversely affected. I don't give it.

  Further, since the flange portion 5 is embedded in the concrete 3 so as to contact the surface of the earthquake resistant wall 2, the crack 7 does not penetrate the earthquake resistant wall 2 as shown in FIG. 6. Therefore, carbon dioxide or moisture does not enter the inside of the earthquake-resistant wall 2 through the crack 7 and the rebar 8 is not rusted, and the durability can be further improved. It is possible to prevent deterioration of waterproofness. Furthermore, since the flange part 5 is linearly formed by a strip-shaped flat plate, the aesthetic appearance is not impaired.

  Next, a crack inducing joint according to a second embodiment of the present invention will be described with reference to FIGS. Here, FIG. 7 is a perspective view showing a state in which the crack-inducing joint according to the second embodiment of the present invention is attached to the earthquake-resistant wall, and FIG. 8 shows the crack-inducing joint according to the second embodiment of the present invention. FIG. 9A is a plan view showing a modification of the crack-inducing joint according to the second embodiment of the present invention, FIG. 9B is a perspective view thereof, and FIG. 10 (a) is a plan view showing another modification of the crack-inducing joint according to the second embodiment of the present invention, and FIG. 10 (b) is a crack-inducing joint according to the second embodiment of the present invention. FIG. 11 is a cross-sectional view showing a state in which a crack-inducing joint according to the second embodiment of the present invention is attached to a seismic wall.

  As shown in FIG. 7, the crack-inducing joint 10 according to the present embodiment is made of a material having a compressive strength equal to or higher than that of the concrete 3 of the reinforced concrete seismic wall 2 such as stainless steel or ceramic. It is formed, and is constituted by an embedded portion 11 embedded in the earthquake-resistant wall 2 and a flat end portion 12 embedded in the concrete 3 so as to be in contact with the surface of the earthquake-resistant wall 2. The crack-inducing joint 10 has a thickness of about 1 to 2 mm, for example, and is formed so that the embedding width of the embedding portion 11 on one side is about 10 to 15% of the wall thickness of the earthquake resistant wall 2. ing.

  The embedding part 11 has a shape in which a strip-shaped plate material is unevenly formed in a zigzag shape in a direction intersecting with a shearing stress generation direction (arrow direction in FIG. 8). The embedded portion 11 is not limited to this shape. For example, as shown in FIGS. 9A and 9B, the shape of the metal pieces 16 alternately cut and raised to the opposite side, or FIG. (A), as shown in (b), a shape in which ridges 15 are formed at predetermined intervals on the embedding surface 14 of a trapezoidal rod-shaped ceramic body 13 in a plan view, or a corrugated shape, although not particularly shown. Other shapes may be used as long as they have a shape that is uneven in the direction intersecting the shear stress generation direction (the arrow direction in FIG. 8), such as a round shape, a punching metal shape, and an expanded metal shape. .

  And the crack induction joint 10 which concerns on embodiment of this invention provided with the above-mentioned structure is fixed to concrete formwork (illustration omitted) using a temporary fixing member, concrete is cast, and the earthquake-resistant wall 2 11 is embedded in the surface portions on both sides of the plate at a predetermined interval, stress is concentrated on the installation portion of the crack-inducing joint 10 due to the shrinkage due to drying of the concrete as shown in FIG. Can be triggered.

  As described above, according to the crack-inducing joint 10 according to the above-described embodiment, it is possible to reliably induce a crack along the crack-inducing joint 10 without providing a cracked portion. It can be suppressed to a minimum thickness, the amount of concrete and weight can be reduced, and the effective area of the room can be increased.

  In addition, the crack-inducing joint 10 is made of a material having a compressive strength equal to or higher than that of the concrete 3 of the earthquake resistant wall 2 and is uneven in a direction intersecting with the direction of occurrence of shear stress (arrow direction in FIG. 8). Because it has a shape that can transmit shear stress along the crack-induced joint 10, the structural performance as the earthquake-resistant wall 2 can be sufficiently exerted, and the durability of the earthquake-resistant wall 2 is adversely affected. Never give.

  Furthermore, the end portion 12 is embedded in the concrete 3 so as to be in contact with the surface of the earthquake resistant wall 2 and is formed linearly by a flat plate, so that the aesthetic appearance is not impaired.

  In the case of the present embodiment, since the flange portion is not formed, as shown in FIG. 11, there is a possibility that the crack 7 may penetrate the earthquake resistant wall 2, but the surface of the earthquake resistant wall 2 is waterproof and sound insulating. By applying or sticking a finishing material that has rust, carbon dioxide and moisture can be prevented from entering the inside of the earthquake-resistant wall 2 through the cracks 7 and rusting of the reinforcing bars 8 to improve durability. In addition, it is possible to prevent the sound insulation and waterproofing from being lowered due to the occurrence of the crack 7.

1 Crack-induced joint 2 Seismic wall (concrete structure)
3 Concrete 4 Embedded part 5 Flange part (end part)
10 Crack-induced joint 11 Embedment 12 End

Claims (2)

A crack-inducing joint provided to generate cracks in a concrete structure in a planned manner,
It is composed of a material having a compressive strength equal to or higher than that of the concrete of the concrete structure, embedded in the concrete so that the end is in contact with the surface of the concrete structure, the end is formed in a straight line, The crack-inducing joint characterized in that the embedded portion has a shape that is uneven in a direction that intersects with the direction of shear stress generation of the concrete. The crack-inducing joint according to claim 1, wherein a flange portion is formed at the end portion so as to contact the surface of the concrete structure.

Images