JP2012177284A - Crack control method of reinforced-concrete wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack control method of reinforced-concrete wall with which a cracks are concentrated to joint positions without using an induction member such as a hollow mortar pipe which causes reduction of structure durability at the joint position or a crack induction steel bar in which rusting caused by water infiltrated from the crack becomes a problem, and further, without increasing a joint depth of a rack induction joint.SOLUTION: An unboned tendon 2 is buried in a horizontal direction into a reinforced-concrete wall 1 between crack induction joints (a) and (a), an opening 3 for tensioning the tendon is formed beforehand. After concrete is hardened, the tendon is tensioned by tensioning work in the opening, a prestress P in the horizontal direction is introduced to the reinforced-concrete wall between the crack induction joints, and the opening is filled with grout members 4 thereafter.

Description

  The present invention relates to a method for controlling cracks in a reinforced concrete wall that controls cracks in a reinforced concrete wall having crack-inducing joints so that cracks are reliably concentrated at joint positions and cracks are prevented from occurring on wall surfaces other than joint positions.

  Cracks in reinforced concrete walls caused by drying shrinkage, freezing and thawing, temperature stress, etc. of concrete are not a factor that impedes strength, but are serious problems in that they deteriorate the appearance.

  For this reason, reinforced concrete walls are provided with crack-inducing joints for systematically concentrating cracks at the required intervals, but the cracks cannot be completely concentrated at the joint positions, and the walls other than the joint positions are not provided. There were some cases where cracks occurred.

  Of course, increasing the joint depth of the crack-induced joint and increasing the cross-sectional defect rate at the joint position is effective in suppressing the occurrence of cracks on the wall surface other than the joint position, but the cross-sectional defect rate is large. If it passes, the amount of so-called soft concrete (the amount of concrete cast thicker than the wall thickness required for the structure by the joint depth) increases, the building weight also increases, and it is very uneconomical as a whole.

  Further, Patent Document 1 discloses that inductive materials such as hollow mortar pipes and mortar-filled PVC pipes are embedded inside the reinforced concrete walls in accordance with the positions of the crack-inducing joints, or crack-inducing rebars (deformed). There is described a crack-induced joint structure that is devised so that the cracks are concentrated at the joint position without increasing the joint depth of the crack-induced joint by embedding the reinforcing bars in accordance with the joint position.

  However, in the former, the problem that the structural durability at the joint position is harmed by the inducer embedded in the concrete is pointed out. According to the latter, a deformed reinforcing bar (cracking inducing rebar) with a concrete reinforcing function is used as the inducing material, so it is possible to avoid a decrease in structural durability at joints, but the inducing material embedded in the site where cracks are concentrated Is a deformed rebar (crack-inducing rebar), so the adverse effect on concrete when rust is generated by moisture that has penetrated from the crack is extremely large. For this reason, crack-inducing reinforcing bars (deformed reinforcing bars) are required to have a perfect anti-rust treatment, and the presence of pinholes that tend to occur in the anti-corrosive coating film is anxious.

JP 2007-56521 A

  The present invention has been made in view of the above-mentioned problems, and its purpose is to induce a material such as a hollow mortar pipe that causes a decrease in structural durability at the joint position, and intrusion from cracks. To provide a crack control method for reinforced concrete walls that concentrates cracks at joint locations without increasing the joint depth of crack-induced joints, even without the use of crack-inducing rebars that cause water rust. It is in.

  In order to achieve the above object, technical measures taken by the present invention are as follows. That is, the crack control method for a reinforced concrete wall according to the first aspect of the present invention is a crack control method for a reinforced concrete wall having a crack-inducing joint, and the unbonded tension material is horizontally applied to the reinforced concrete wall between the crack-inducing joints. In addition to burying in the direction, an opening for tension work of the tension material is formed, and after hardening of the concrete, the tension material is tensioned by tension work at the opening, and it is horizontal to the reinforced concrete wall between the crack-induced joints. After introducing the direction prestress, the opening is filled with a grout material.

  The invention according to claim 1 includes a case where an opening for tension work of a tension material is formed at a position corresponding to one end of the tension material, and a case where the opening is formed at a position corresponding to an intermediate portion of the tension material. Is included.

  Invention of Claim 2 is the crack control method of the reinforced concrete wall of Claim 1, Comprising: An opening part is formed in the position corresponding to the intermediate part of a tension material, and both ends of a tension material are made into a fixed end, It is characterized by tensioning the tendon by simultaneously pulling the middle part of the tendon in the opposite direction.

  Invention of Claim 3 is the crack control method of the reinforced concrete wall of Claim 2, Comprising: The intermediate part of a tension material is simultaneously pulled in the reverse direction with a turnbuckle, and the tension material is tensioned. .

  According to the first aspect of the present invention, the horizontal prestress is introduced into the reinforced concrete wall between the crack-inducing joints, and a tensile force acts on the crack-inducing joints in the direction of expanding the joint width. Cracks caused by freezing and thawing, temperature stress, and the like are surely concentrated at the position of the crack-induced joint, and the occurrence of cracks on the wall surface other than the joint position can be suppressed.

  In particular, by introducing horizontal prestress in the reinforced concrete walls between the crack-inducing joints, the cracks are concentrated at the joint position, so when hollow mortar pipes and crack-inducing rebars are embedded according to the joint position. As described above, the structural durability at the joint position is not lowered, and the problem of rust generation due to intrusion water from cracks does not occur in principle.

  In addition, the horizontal prestress introduced into the reinforced concrete wall is released by concentrating and generating cracks due to drying shrinkage, freezing and thawing, temperature stress, etc. of the concrete at the joints. However, it is not necessary to leave the prestress after the cracks are concentrated on the joints. Therefore, as a prestressing tension material and tension applying means, structures such as beams and floors are used. As compared with a tension applying means such as a permanent tension material or a hydraulic jack that reinforces the tension, it is sufficient to apply tension by manpower operation.

  According to invention of Claim 2, the opening part for tension | tensile_strength work of a tension | tensile_strength is formed in the position corresponding to the intermediate part of a tension | tensile_strength, both ends of a tension | tensile_strength are made into a fixed end, Since the tension material is tensioned by simultaneously pulling the middle part of the material in the opposite direction, the fixed ends of the tension material can be disposed close to the crack-inducing joints on both sides, and in this respect also, it is easy to concentrate the cracks at the joint positions.

  According to the invention described in claim 3, since the tension member is tensioned by simultaneously pulling the tension member in the opposite direction by the turnbuckle in the opening, the tension force is maintained even if the hand is released from the turnbuckle. The tension management is easy.

It is a side view of the state which arranged the tendon which shows the embodiment of the present invention. It is a side view of the state which cast concrete and removed the formwork. It is a side view of the state which introduced prestress and filled up the grout material in the opening part. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a perspective view of the principal part. It is a cross-sectional top view of the principal part which shows other embodiment. It is a perspective view of the principal part which shows other embodiment. It is a cross-sectional top view of the principal part. It is a perspective view of the principal part which shows other embodiment. It is a perspective view of the principal part. It is a side view which shows other embodiment. It is the BB sectional drawing of FIG.

  1 to 5 show an example of a crack control method for a reinforced concrete wall according to the present invention. As shown in FIGS. 1 to 4, this crack control method is applied to a reinforced concrete wall 1 in which a longitudinal crack-inducing joint a is formed by in-situ casting of concrete. The unbonded tension material 2 is embedded in the horizontal direction, and an opening 3 for tension work of the tension material 2 is formed at a position corresponding to the intermediate portion of the tension material 2. The tension material 2 is tensioned by the tension work in the section 3, and the horizontal prestress P by the post tension method is introduced into the reinforced concrete wall 1 between the crack-inducing joints a and a, and then the opening 3 is not contracted. It is characterized by filling the grout material 4 such as mortar and burying the tension end (intermediate portion) of the tension material 2.

  More specifically, as shown in FIG. 1, when the wall reinforcement 5 is laid out, it is unbonded between the crack-induced joint formation scheduled positions and in the vicinity of the wall core or in the vicinity of the wall core, so that it is intermediate in the longitudinal direction. A tension material 2 having a sleeve 6 for forming the opening 3 is disposed in a plurality of stages (a center position in the longitudinal direction is desirable) in a plurality of stages, and is disposed through a kansai streak or a wire (not shown). It is supported by the wall muscle 5.

  Inside the sleeve 6, a turnbuckle 7 is incorporated as a tension applying means for pulling and tensioning the intermediate part of the tension material 2 in the opposite direction at the same time. As shown in FIG. 5, the turnbuckle 7 has a hook 7a with a reverse screw at both ends, and a ring-shaped portion 2a in which a folded portion is caulked with a cylindrical hardware at a tension end of the tension member 2. Is formed and engaged with the hook 7a. Accordingly, if necessary, the turnbuckle 7 is separated and the turnbuckle 7 is inserted into the sleeve 6 after the tensioning material 2 is disposed (for example, after the concrete is hardened) and attached to the tensioned end of the tensioning material 2. You can also. Supporting plates 8 are attached to both ends (fixed ends) of the tendon 2. In the illustrated example, as shown in FIG. 5, the tension material 2 is inserted in advance through a small hole of the sleeve 6. However, a slit is formed in the sleeve 6, and after the sleeve 6 is installed, the tension material 2 is slit. Conversely, the sleeve 6 may be attached to the tension member 2 through a slit after the tension member 2 is disposed.

  Tensile material 2 includes Kevlar sheet, carbon fiber, PE (ultra high molecular weight polyethylene) line, PC steel wire (piano wire), PC steel bar, PC steel stranded wire (strand wire), etc. A high material is appropriately selected. When the surface of the tension material 2 is unbonded so as not to adhere to the concrete after hardening, various types of materials are used depending on the material of the tension material 2 such as covering with a sheath tube and applying grease or other adhesion prevention materials. Can be adopted.

  After placing the tendon 2, a wall mold (not shown) is assembled, and concrete 9 is placed in the mold leaving the opening 3 in the sleeve 6 as shown in FIG. 2. After the concrete 9 is hardened and demolded, the turnbuckle 7 in the opening 3 is manually operated to rotate, and the tensioning material 2 is tensioned by simultaneously pulling the middle part of the tensioning material 2 in the opposite direction by the turnbuckle 7. A prestress P in the horizontal direction is introduced into the reinforced concrete wall 1 between the crack-inducing joints a and a. In this case, due to the mechanism of the turnbuckle 7, even if the hand is released from the turnbuckle 7, the tension force is not lost, and the tension management is easy.

  Thereafter, as shown in FIGS. 3 and 4, the opening 3 is filled with the grout material 4, and the tension end (intermediate portion) of the tension material 2 including the turnbuckle 7 is buried, and the crack-inducing joint a is formed. The construction of the reinforced concrete wall 1 is completed.

  According to the above configuration, the horizontal prestress P is introduced into the reinforced concrete wall 1 between the crack-inducing joints a and a, and a tensile force acts on the crack-inducing joints a and a in the direction of expanding the joint width. Cracks caused by drying shrinkage, freezing and thawing, temperature stress, and the like of the concrete are surely concentrated at the positions of the crack-inducing joints a and a, and the occurrence of cracks on the wall surfaces other than the joint positions can be suppressed.

  In addition, the tension work opening 3 of the tension material 2 is formed at a position corresponding to the intermediate portion of the tension material 2, both ends of the tension material 2 are fixed ends, and the tension material 2 is intermediate between the openings 3. Since the tension members 2 are tensioned simultaneously by pulling the parts in the opposite direction, the fixed ends (bearing plate 8) of the tension members 2 can be arranged close to the crack-inducing joints a and a on both sides. Easy to concentrate on the position.

  In particular, by introducing prestress P in the horizontal direction to the reinforced concrete wall 1 between the crack-inducing joints a and a, the cracks are concentrated at the joint position. Therefore, hollow mortar pipes and cracks are induced according to the joint position. As in the case of embedding reinforcing bars, there is no problem in principle of deterioration of structural durability at joint positions or rust generation due to intrusion water from cracks.

  Further, the horizontal prestress P introduced into the reinforced concrete wall 1 is released in accordance with the concentration of cracks caused by drying shrinkage, freezing and thawing, temperature stress, etc. of the concrete at the joint position. However, it is not necessary to leave the prestress P after cracks are concentrated on the joints. Therefore, the tension material 2 for introducing pre-stress and the tension applying means need only be lighter than permanent tension materials or hydraulic jacks that reinforce structures such as beams and floors. As in the form, it is possible to apply the turnbuckle 7 as tension applying means and apply tension by human power.

  In the example of FIG. 5, the turn buckle 7 having a reverse threaded hook 7 a is used as the turn buckle 7, and the ring-shaped portion 2 a that engages with the hook 7 a is formed at the tension end of the tension material 2. However, when the tension material 2 is a material that can be threaded, such as a PC steel wire or a PC steel rod, the turnbuckle 7 may be formed by directly threading the tension material 2 as shown in FIG. it can.

  7 and 8 show another embodiment of the present invention. In this embodiment, the tendon 2 is made of a small diameter PC steel wire (piano wire) or other material that is easily bent and deformed, and in the opening 3, the intermediate part of the tendon 2 is simultaneously pulled in the opposite direction. As a tension applying means for tensioning 2, there is a feature in that a winder 11 using a worm gear 10 is used.

The winder 11 is rotationally driven by a worm gear 10 having a rotation operation unit 10a at one end, and a rotary shaft 12 that is rotationally driven by the worm gear 10 and has a slit 12a sandwiching an intermediate portion of the tension material 2 at the tip. The base plate 13 is freely supported. After the concrete 9 is hardened, the winder 11 is inserted into the opening 3, and the worm gear 10 is rotated in a state where the intermediate portion of the tension material 2 is sandwiched between the slits 12 a at the tip of the rotary shaft 12. The intermediate portion is wound around the rotary shaft 12 so that the tension material 2 is tensioned. The sleeve 6 abuts against the edge of the base plate 13 such as an ellipse or a square so that the tension member 2 does not rotate together with the base plate 13 due to the restoring force of the tension material 2 to return to the original state. The cross-sectional shape can be blocked. Since other configurations and operations are the same as those of the previous embodiment, description thereof is omitted.

  Although not shown, it is also possible to configure a winder 11 that uses the ratchet mechanism to detent the rotating shaft 12 in place of the worm gear 10.

  9 and 10 show another embodiment of the present invention. In this embodiment, the tendon 2 is made of a small diameter PC steel wire (piano wire) or other material that is easily bent and deformed, and in the opening 3, the intermediate part of the tendon 2 is simultaneously pulled in the opposite direction. As a tension applying means for tensioning 2, there is a feature in that a square wedge 14 in which a slit 14 a for sandwiching an intermediate portion of the tension material 2 is formed at the tip is used. Reference numeral 14 b denotes a boss portion having a circular cross section formed in the middle portion in the longitudinal direction of the square wedge 14. Reference numeral 15 denotes a bearing plate on which a bearing portion 15a for rotatably supporting the boss portion 14b of the square wedge 14 is formed. The bearing plate 15 is installed in a state in which both ends protrude from the outer peripheral surface of the sleeve 6 on the sleeve 6 having a split structure, and is embedded in the concrete 9 together with the sleeve 6.

  According to the above configuration, after the concrete 9 is hardened, as shown in FIGS. 9B and 10, the rectangular wedge 14 is supported in the opening 3 in the sleeve 6 and the boss portion 14b is supported by the bearing portion 15a. The intermediate portion of the tension member 2 is inserted into the slit 14a, and the intermediate portion of the tension member 2 is inserted into the slit 14a. In this state, the intermediate wedge 14 is rotated with an appropriate tool such as a spanner. The tension material 2 can be tensioned by winding around the tip of the wedge 14 and simultaneously pulling the intermediate portion of the tension material in the opposite direction.

  Then, while maintaining this tension state, as shown in FIG. 10, the lock plate 16 having a plurality of square holes 16 a corresponding to the plurality of square wedges 14 is fitted to the square wedge 14, thereby The reverse rotation of the square wedge 14 by the restoring force that the material 2 tries to return to is prevented. Thereby, the horizontal prestress by a post tension system is introduced into the reinforced concrete wall between crack induction joints.

  When the grout material 4 filled in the opening 3 in the sleeve 6 is hardened, the tip side of the square wedge 14 protruding from the square hole of the lock plate 16 is cut and removed to construct the reinforced concrete wall 1 having the crack-inducing joint a. Complete. The lock plate 16 may be removed or embedded in the wall finish.

  In each of the above embodiments, the tensioning material opening 2 for the tensioning material 2 is formed at a position corresponding to the intermediate part of the tensioning material 2, and both ends of the tensioning material 2 are fixed ends. Although the tension member 2 is tensioned by simultaneously pulling the middle part of the tension member 2 in the opposite direction, one end of the tension member 2 is used as a fixed end and the other end of the tension member 2 is introduced in the same manner as the pre-stress introduction by a general post tension method. In the case of a tension end, as shown in FIGS. 11 and 12, an opening 3 is formed at a position corresponding to one end of the tension material 2, and the tension material 2 is moved in one direction by an operation in the opening 3. The tension material 2 will be tensioned by pulling on. In this case, it is preferable to use the nut 17 as the tension applying means in order to improve the accommodation of the tension end. Other configurations and operations are the same as those of the previous embodiment, and thus description thereof is omitted.

P Prestress a Cracking joint 1 Reinforced concrete wall 2 Tension material 2a Ring-shaped part 3 Opening part 4 Grout material 5 Wall reinforcement 6 Sleeve 7 Turnbuckle 7a Hook 8 Bearing plate 9 Concrete 10 Warm gear 10a Rotating operation part 11 Winding tool 12 Rotation Shaft 12a Slit 13 Base plate 14 Square wedge 14a Slit 14b Boss part 15 Bearing plate 15a Bearing part 16 Lock plate 16a Square hole 17 Nut

Claims (3)

  A crack control method for a reinforced concrete wall having a crack-inducing joint, in which an unbonded tension material is embedded horizontally in the reinforced concrete wall between the crack-induced joints and an opening for tensioning the tension material is formed. In addition, after the concrete is hardened, the tension material is tensioned by the tension work at the opening, and after introducing horizontal prestress into the reinforced concrete wall between the crack-inducing joints, the opening is filled with grout material. The crack control method of the reinforced concrete wall characterized by this.   The opening is formed at a position corresponding to an intermediate portion of the tendon, both ends of the tendon are fixed ends, and the tendon is tensioned by simultaneously pulling the intermediate portion of the tendon in the opposite direction. The crack control method of the reinforced concrete wall as described in 2.   The method for controlling cracks in a reinforced concrete wall according to claim 2, wherein the tension material is tensioned by simultaneously pulling the middle portion of the tension material in the opposite direction with a turnbuckle.

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