JP2016014312A - Deformation control method and belt-like fastening member for reinforcing steel plate used on reinforced concrete column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deformation control method for a reinforcing steel plate used on a reinforced concrete column that is implemented easily even in a narrow work space and capable of certainly preventing swelling of the reinforcing steel plate.SOLUTION: When a reinforced concrete column is reinforced by placing a reinforcing steel plate around the reinforced concrete column and injecting and hardening mortar between the reinforced concrete column and the reinforcing steel plate, the method comprises, between the step for covering an outer periphery of the reinforced concrete column with the reinforcing steel plate and the step for injecting and hardening mortar; the step for fitting a plurality of rod-form members that extend along a height direction of the reinforced concrete column at an outside of a central part of the reinforcing steel plate; the step for winding a belt-like member on outside of the rod-form members; and the step for fastening both ends of the belt-like member using a fastening member while applying tension on the belt-like member, so as to forcibly hold down a swollen part of the reinforcing steel plate when the reinforcing steel plate swells during mortar injection.

Description

  The present invention relates to a method for reinforcing a reinforced concrete column such as a pier, for example, and in particular, a method for preventing a steel plate from protruding when a mortar is injected between a reinforced concrete column and a reinforcing steel plate, and the reinforcing steel plate. The present invention relates to a belt-like member used for tightening.

  Conventionally, in order to improve the earthquake resistance of reinforced concrete columns, the surroundings of reinforced concrete columns are surrounded by reinforcing steel plates, and then epoxy resin or mortar is injected between the reinforced concrete columns and the reinforcing steel plates to reinforce the reinforced concrete columns and reinforcing steel plates. Are known to be integrated with each other (see, for example, Patent Documents 1 and 2).

  By the way, a so-called bulging occurs in which the reinforcing steel plate is deformed so as to bulge outward by a hydraulic pressure when mortar is injected between the reinforced concrete column and the reinforcing steel plate. Therefore, conventionally, as shown in FIG. 10, the reinforcing steel plate 12 surrounding the reinforced concrete column 11 is tightened with a column-shaped frame fastening tool such as an aluminum column 15 to suppress the protrusion of the reinforcing steel plate 12. I was trying to do it.

JP 2007-270511 A JP 2005-23745 A

However, in the method using the above-described column-type frame fastener, it is necessary to lift the pipe 15a having a heavy weight of 30 kg or more and have a poor balance to be assembled into a frame shape. Not only is it time-consuming, but also it is difficult to uniformly restrain the reinforcing steel plate 12, so that irregularities may occur on the reinforcing steel plate surface.
Further, since a large space is required to store a large number of pipes 15a, there is a problem that the place of installation is troubled when the construction yard is small such as reinforcement of a pier.

  The present invention has been made in view of the conventional problems, and is a method for suppressing deformation of a reinforced concrete column reinforcing steel plate that can be easily installed even in a narrow construction space and can reliably prevent the reinforcing steel plate from protruding. It aims at providing the strip | belt-shaped member used suitably for fastening of the steel plate for reinforcement.

The present invention is a method for suppressing deformation (protruding) of the reinforcing steel plate, which occurs when mortar is injected between the reinforcing steel plate arranged around the reinforced concrete column to be reinforced and the reinforced concrete column. Between the step of placing a reinforcing steel plate around the reinforced concrete column and covering the outer periphery of the reinforced concrete column and the step of injecting and hardening mortar between the reinforced concrete column and the reinforcing steel plate, A step of attaching a plurality of rod-shaped members extending along the height direction of the reinforced concrete column to the outside of the central portion of the reinforcing steel plate, a step of winding a strip-shaped member around the rod-shaped member, and both ends of the strip-shaped member And a step of using a fastening member to fasten the belt-like member in a tensioned state.
Thereby, since the protrusion of the reinforcing steel plate generated at the time of mortar injection can be effectively suppressed, the appearance after reinforcement can be improved. Moreover, since a rod-shaped member should be applied along the height direction of a reinforcement member and a strip | belt-shaped member should just be wound around the outer periphery, construction becomes easy also in a narrow construction space.
In addition, since the angle between the strip-shaped member and the reinforcing steel plate in the cross section perpendicular to the extending direction of the reinforced concrete column is in the range of 10 ° to 30 °, the reinforcing steel plate is effective when protruding from the reinforcing steel plate. Can be tightened.

Further, the belt-like member has high strength and high elasticity, with a tensile strength of 2.06 [kN / mm ² ] or more, an elastic modulus of 118 [kN / mm ² ] or more, and a breaking elongation of 2.4 [%] or less. Since it is comprised from the fiber which has a rate, the protrusion of the steel plate for reinforcement can be forced down.
Further, if the fiber is an aramid fiber and the fastening member is a winding buckle that winds and fixes the band-shaped member made of the aramid fiber, the rod-shaped member can be pressed against the reinforcing steel plate with a simple configuration. In addition, the strip member and the fastening member can be reused.

  In addition, a plurality of the band-shaped members are arranged in the height direction of the reinforced concrete column, and the interval between the band-shaped members on the lower side of the reinforced concrete column is made smaller than the interval between the band-shaped members on the upper side of the reinforced concrete column. Therefore, the protrusion of the entire reinforcing steel sheet can be suppressed within an allowable range and evenly.

Further, the present invention is a band member for fastening used in a method for suppressing deformation of a steel plate for reinforcing reinforced concrete columns, comprising an adhesive tape attached to a surface of the band member on the rod-like member side. To do.
As described above, the adhesive tape is attached to the surface of the strip-shaped member made of aramid fibers (hereinafter referred to as an aramid belt) so as to improve the flatness retention of the aramid belt surface. The drawbacks can be improved.
Moreover, you may make it raise the planar retainability of an aramid belt surface by sewing a resin sheet instead of an adhesive tape.
Alternatively, the aramid fibers constituting the aramid belt may be impregnated with a resin that maintains flexibility even after curing, such as a urethane resin. Thereby, since the aramid belt can be bent while being held flat, the twist of the aramid belt can be reduced.

  The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a figure which shows the protrusion prevention material of the steel plate for reinforced concrete pillar reinforcement which concerns on embodiment of this invention, and its installation method. It is a figure which shows an example of the aramid belt with a ratchet buckle. It is a figure which shows the example of arrangement | positioning in which a rod-shaped member is not effective. It is a flowchart which shows the protrusion prevention method of the steel plate for reinforced concrete pillar reinforcement by this invention. It is a figure which shows a protrusion prevention material and its installation procedure. It is a figure which shows the ramen pier used as the measuring object of the protrusion amount of the steel plate for reinforcement. It is a graph which shows the measurement result of the protrusion amount of the steel plate for reinforcement. It is a figure which shows the other example of the aramid belt with a ratchet buckle. It is a figure which shows the other example of the aramid belt with a ratchet buckle. It is a figure which shows the protrusion prevention method of the conventional steel plate for reinforcement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 (a) and 1 (b) are diagrams showing an aramid belt protrusion preventing material 1 used in a method for reinforcing a reinforced concrete column 11 according to the present embodiment and an installation method thereof. The aramid belt 2 with a ratchet buckle, a square steel pipe 3 and a square wood 4 are provided.
In this example, the cross-sectional shape of the reinforced concrete column 11 is a square, and the reinforcing steel plate 12 is disposed so as to surround the outside of the reinforced concrete column 11.
The aramid belt 2 with a ratchet buckle is a combination of an aramid belt 21 as a belt-like member and a ratchet buckle 22 as a fastening member.
The aramid belt 21 is made of high-strength and high-modulus aramid fibers having a tensile strength of 2.06 [kN / mm ² ], an elastic modulus of 118 [kN / mm ² ], and a breaking elongation of 2.4 [%]. As shown in FIGS. 2A and 2B, one end 21a is fixed to the fixed shaft 22a of the ratchet buckle 22 and the other end 21b is an aramid belt 21. Is wound around the object to be tightened and then led out to the outside of the winding shaft 22b through a slit (not shown) of the winding shaft 22b. In this example, one end 21a is wound around the fixed shaft 22a and extended to the outside of the fixed shaft 22a, and then the overlapped portion of the aramid belt 21 is impregnated with epoxy resin and bonded to form a retaining portion 21m. The other end 21b side is also impregnated with an epoxy resin to form a fray preventing portion 21n so that the aramid fiber on the other end 21b side is not frayed.
When the aramid belt 2 with the ratchet buckle is fastened, the handle 22c is repeatedly operated one or more times to rotate the ratchet wheel 22d fixed to the winding shaft 22b, and the other end 21b side of the aramid belt 21 is rotated around the winding shaft. Wind up around 22b. Thereby, the length of the aramid belt 21 between the ratchet buckles 22 can be shortened, and the loading can be performed. That is, at the time of cargo tightening, both end portions 21 a and 21 b of the aramid belt 21 are fastened with a ratchet buckle 22 in a tensioned state.

Each of the square steel pipe 3 and the square wood 4 is a rod-shaped member having a length equal to the mortar injection height and having a square cross-sectional shape. As will be described later, the square steel pipe 3 and the square wood 4 Are integrated to form the rod-shaped member 5 of the present invention.
The square steel pipe 3 is arranged at the center of the four surfaces of the reinforcing steel plate 12, and the square wood 4 is arranged on the surface of the square steel pipe 3 opposite to the reinforcing steel plate 12.
The aramid belt 21 is fastened by a ratchet buckle 22 after being wound around the outer periphery of the square wood 4. In this way, if the outer peripheral portion of the reinforcing steel plate 12 is constrained by the aramid belt 2 with a ratchet buckle via the rod-like member 5, the aramid belt 21 has a characteristic that hardly extends, so that it is used for reinforcement when mortar is injected. When the steel plate 12 protrudes, the protrusion can be forcibly suppressed.

In this example, as shown to Fig.1 (a), while arrange | positioning the rod-shaped member 5 in the center of each edge | side of the reinforcing steel plate 12, the angle which the aramid belt 21 and the reinforcing steel plate 12 make is 10 degrees-30 degrees. It is said. That is, as shown in FIG. 3 (a), when the rod-like member 5 is arranged at the end of each side of the reinforcing steel plate 12, or as shown in FIG. 3 (b), the rod-like member 5 is used as the reinforcing steel plate. When the reinforcing steel plates 12 are arranged symmetrically with respect to the center of each side, a moment for rotating the rod-shaped member 5 acts on the rod-shaped member 5 when the reinforcing steel plate 12 protrudes. Is difficult to suppress. On the other hand, in this example, since the rod-shaped member 5 is located at the center of the aramid belt 21, the rotational moment from the left and right aramid belts 21 acting on the rod-shaped member 5 is canceled, and as a result, the rod-shaped member 5 Applies only the force in the direction perpendicular to each side of the reinforcing steel plate 12, that is, the direction in which the reinforcing steel plate 12 is prevented from protruding, to the reinforcing steel plate 12 reliably. can do.
Here, when the length of the bar-shaped member 5 in the direction perpendicular to the reinforcing steel plate 12 is the thickness of the bar-shaped member 5, the angle between the aramid belt 21 and the reinforcing steel plate 12 is reduced by reducing the thickness of the bar-shaped member 5. When the angle is less than 10 °, the force in the direction of suppressing the protrusion of the reinforcing steel sheet 12 becomes small, and the effect of suppressing the protrusion of the reinforcing steel sheet 12 is not sufficient. Conversely, if the thickness of the bar-shaped member 5 is such that the angle formed by the aramid belt 21 and the reinforcing steel plate 12 exceeds 30 °, it is difficult to stably press the bar-shaped member 5 against the reinforcing steel plate 12. Therefore, the angle formed by the aramid belt 21 and the reinforcing steel plate 12 is preferably 10 ° to 30 °.

  As shown in FIG. 1B, a plurality of aramid belts 2 with ratchet buckles are arranged in the height direction of the reinforced concrete columns 11, and the distance between the aramid belts 2 with ratchet buckles on the lower side of the reinforced concrete columns 11 is set. The distance between the aramid belts 2 with the ratchet buckle on the upper side of the reinforced concrete column 11 is preferably narrower. This is because when the mortar is injected between the reinforced concrete column 11 and the reinforcing steel plate 12, the hydraulic pressure acts as a larger value in the lower part, so the aramid belt 2 with a ratchet buckle is installed densely in the lower part. Thereby, the protrusion of the entire reinforcing steel plate 12 can be made uniform within an allowable range.

Next, a method for reinforcing a reinforced concrete column using the aramid belt protrusion preventing material 1 of the present invention will be described with reference to the flowchart of FIG.
First, as shown to Fig.5 (a), after arrange | positioning the reinforcing steel plate 12 around the reinforced concrete pillar 11 and covering the outer periphery of the reinforced concrete pillar 11 (step S10), the center part of each side of the reinforcing steel plate 12 The square steel pipe 3 and the square wood 4 are attached to the outside (step S11). Specifically, by attaching a fixture such as a hook to the square steel pipe 3 and the upper end portion of the square wood 4, and attaching this fixture to the upper end portion of the reinforcing steel plate 12, the square steel pipe 3 and the square shape are attached. The wood 4 is attached to the reinforcing steel plate 12.
Then, after winding the aramid belt 2 with a ratchet buckle around the outside of the square wood 4 (step S12), both ends of the aramid belt 21 are fastened by the ratchet buckle 22 and the reinforcing steel plate 12 is fastened. As shown in (b), the square steel pipe 3 and the square wood 4 are fixed to the reinforcing steel plate 12 (step S13). The dimensions of the square steel pipe 3 and the square wood 4 are set so that the angle formed by the aramid belt 21 and the reinforcing steel plate 12 is 22 ° when the aramid belt 2 with a ratchet buckle is fastened.
Next, mortar is injected and hardened between the reinforced concrete pillar 11 and the reinforcing steel plate 12 (step S14).
When the injected mortar is hardened, the aramid belt 2 with a ratchet buckle is loosened, and then the other end 21b side of the aramid belt 21 is removed from the ratchet buckle 22, and the aramid belt 2 with a ratchet buckle and a square wood as an anti-extrusion member 4 and the square steel pipe 3 are collected (step S15).

[Experimental example]
As shown in FIGS. 6 (a) and 6 (b), a ramen pier having a total length of about 550 cm (lower floor 121; 100 cm, indoor portion 122; 250 cm, ceiling portion 123; 200 cm), and a cross section of 80 cm × 80 cm. 7 shows the result of measuring the amount of protrusion of the reinforcing steel sheet when the aramid belt protrusion preventing material 1 is applied to the steel sheet 12 that is surrounded by the reinforcing steel sheet 12 of 4.5 mm and reinforced against earthquakes.
In the experiment, as the reinforcing steel plate 12, a reinforcing steel plate member 12k provided with concave and convex portions for locking in the vertical direction and the longitudinal direction, disclosed in Patent Document 2, is wound around the bridge pier, and these reinforcements are further provided. Although a plurality of steel plate members 12k engaged in the vertical direction are used, a conventional pair of U-shaped reinforcing steel plates may be attached and welded together.
In the experiment, after injecting mortar into about 100cm at the lower end in advance, install an aramid belt protrusion prevention material inside the room, inject mortar into a section of about 450cm to the top, and at several locations on the reinforcing steel plate. A strain gauge was installed on the steel plate and the amount of protrusion of the reinforcing steel plate was measured.
The amount of protrusion y is obtained by measuring the strain ε of the reinforcing steel plate with a strain gauge, and assuming that one side of the reinforcing steel plate is a both-end fixed beam having a length L. It calculated using.
y = (L ² /4)×(ε/0.6) (1)
As the mortar, Taiheiyo Pre-Eurox LW30 (trade name; manufactured by Taiheiyo Materials Co., Ltd.), which is lightweight with a unit volume mass of 1.533 kg / cm ³ , was used.
In addition, as a square steel pipe, a general structural square steel pipe (STKR400) having a dimensional specification of 10 × 10 × 250 cm and t = 2.3 mm was used. In addition, 90 × 90 × 250 cm wood was used as the square wood.
As an aramid belt, Hybelas construction belt sheet AK-240 (trade name) manufactured by Fivebeck Co., Ltd. was used. The belt dimensions are 510cm in length, 5cm in width, 0.5kg in weight, and 11.79kN in design load capacity.
As a ratchet buckle, R50LW (trade name) manufactured by Ancra Japan Co., Ltd. was used. The buckle has a weight of 1.08kg and a breaking strength of 49kN.
The angle formed between the aramid belt and the reinforcing steel plate was 22 °.

As shown in the graph of FIG. 7, in the lower part of the pier (h = 47.5 cm and h = 77.5 cm), the mortar hardens with the passage of time, and in the vicinity of 40 to 50 minutes (the mortar injection height is about 200 cm). It can be seen that the protruding amount y becomes a constant value, and the deformation of the reinforcing steel plate is converged. Further, it can be seen that the maximum value of the protruding amount y is about 0.06 cm, which is much smaller than the designed value (about 0.3 cm or less). It can also be seen that at the upper part of the pier (h = 205.0 cm), the protruding amount y becomes a constant value in a shorter time compared to the lower part of the pier.
Thereby, it was confirmed that the protrusion of the reinforcing steel sheet can be surely suppressed by applying the aramid belt protrusion preventing material of the present invention to the seismic reinforcement method using the reinforcing steel sheet.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

For example, in the above-described embodiment, the rod-shaped member 5 is composed of the square steel pipe 3 and the square wood 4, but is not limited to this, and the cross-sectional shape is rectangular and the length of the longer side (thickness) ) May be the square steel pipe 3 or square wood 4 that is the sum of the length of one side of the square steel pipe 3 and the length of one side of the square wood 4 of the embodiment. In short, the thickness of the rod-shaped member 5 may be set so that the angle formed by the aramid belt 21 and the reinforcing steel plate 12 in the cross section perpendicular to the extending direction of the reinforced concrete column 11 is in the range of 10 ° to 30 °. .
Moreover, in the said embodiment, although the ratchet buckle 22 was used as a fastening member which fastens the aramid belt 21, other fastening members, such as a turn buckle, may be used, for example.

In the embodiment, the aramid belt 21 has a high strength and a high elastic modulus with a tensile strength of 2.06 [kN / mm ² ], an elastic modulus of 118 [kN / mm ² ], and a breaking elongation of 2.4 [%]. Constructed from aramid fibers, but composed of carbon fibers and other fibers with a tensile strength of 2.06 [kN / mm ² ] or more, an elastic modulus of 118 [kN / mm ² ] or more, and a breaking elongation of 2.4 [%] or less May be.

Moreover, in the said embodiment, while using the epoxy resin, while providing the retaining part 21m in the overlapping part of the aramid belt 21, and providing the fraying prevention part 21n on the other end 21b side, as shown in FIG. If the adhesive tape 23 for preventing torsion is attached to the remaining part of the aramid belt 21 so as to improve the flatness of the belt surface, the twist of the aramid belt that occurs when passing through the slit of the buckle, etc. It can be greatly reduced.
As the adhesive tape for preventing twisting, a tape in which an acrylic adhesive 23b is applied to the back surface of a tape-like member 23a such as a polyethylene cloth tape may be used.
In addition, it is preferable to provide the adhesive tape 23 for twist prevention only on the rod-shaped member 5 side which is the back surface of the aramid belt 21 and does not hinder winding by the ratchet buckle.
Alternatively, as shown in FIG. 9, instead of an adhesive tape for twist prevention, a resin sheet 24 for twist prevention made of a resin such as vinyl chloride, polyester, polyvinyl chloride or the like is sewn to the aramid belt 21, thereby You may make it raise the planar retainability of a surface. Even when the resin sheet 24 for preventing twisting is provided, it is preferably provided only on the rod-like member 5 side of the aramid belt 21.
Further, the aramid belt 21 may be impregnated with a resin for preventing torsion that maintains flexibility after curing of a urethane resin or the like. Specifically, a twist preventing resin is applied and impregnated on the surface of the aramid belt 21 using a known coating device. Thereby, since the aramid belt 21 can be bent while being held flat, the twist of the belt that occurs when passing through the slit of the buckle can be greatly reduced.

1 Aramid belt protrusion prevention material, 2 Aramid belt with ratchet buckle,
3 square steel pipe, 4 square wood, 5 rod-shaped member, 11 reinforced concrete column,
12 steel plate for reinforcement, 21 aramid belt, 22 ratchet buckle.

Claims (8)

A method of suppressing deformation of the reinforcing steel plate, which occurs when mortar is injected between the reinforcing steel plate arranged around the reinforced concrete column to be reinforced and the reinforced concrete column,
Between the step of placing a reinforcing steel plate around the reinforced concrete column and covering the outer periphery of the reinforced concrete column and the step of injecting and hardening mortar between the reinforced concrete column and the reinforcing steel plate,
Attaching a plurality of bar-like members extending along the height direction of the reinforced concrete columns to the outside of the central portion of the reinforcing steel plate;
A reinforced concrete column comprising: a step of winding a strip-shaped member around the rod-shaped member; and a step of fastening both ends of the strip-shaped member using a fastening member while the strip-shaped member is tensioned. A method for suppressing deformation of a reinforcing steel plate.   2. The reinforced concrete column reinforcing steel plate according to claim 1, wherein an angle formed between the belt-shaped member and the reinforcing steel plate in a cross section perpendicular to the extending direction of the reinforced concrete column is in a range of 10 ° to 30 °. Deformation control method. The band-shaped member has high strength and high elastic modulus, with a tensile strength of 2.06 [kN / mm ² ] or more, an elastic modulus of 118 [kN / mm ² ] or more, and a breaking elongation of 2.4 [%] or less. It consists of the fiber which has, The deformation | transformation suppression method of the steel plate for reinforced concrete pillar reinforcement of Claim 1 or Claim 2 characterized by the above-mentioned. The fiber is an aramid fiber;
The method for suppressing deformation of a steel plate for reinforcing reinforced concrete columns according to claim 3, wherein the fastening member is a take-up buckle that winds and fixes a belt-like member made of the aramid fiber. While arranging a plurality of the strip members in the height direction of the reinforced concrete pillar,
The reinforced concrete column reinforcement according to any one of claims 1 to 4, wherein an interval between the strip members on the lower side of the reinforced concrete column is narrower than an interval between the strip members on the upper side of the reinforced concrete column. Method for suppressing deformation of steel sheet. A strip-shaped member used in the method for suppressing deformation of a steel plate for reinforcing a reinforced concrete column according to claim 4,
A fastening belt-like member comprising an adhesive tape attached to a surface of the belt-like member on the rod-like member side. A strip-shaped member used in the method for suppressing deformation of a steel plate for reinforcing a reinforced concrete column according to claim 4,
A fastening belt-like member comprising a resin sheet sewn on the surface of the belt-like member of the belt-like member. A strip-shaped member used in the method for suppressing deformation of a steel plate for reinforcing a reinforced concrete column according to claim 4,
A band member for fastening, wherein aramid fibers constituting the band member are impregnated with a resin.

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