JP6893144B2 - Joint structure of concrete rod-shaped member and concrete rod-shaped member - Google Patents

Description

The present invention is a joint structure of a concrete rod-shaped member (steel-framed reinforced concrete member) in which a steel core material is embedded in a rod-shaped concrete body, and a concrete rod-shaped member in which the concrete rod-shaped members are joined to each other (steel-framed reinforced concrete member joint structure). Regarding.

Conventionally, when joining precast concrete steel reinforced concrete members (SRC members) to each other, the steel core materials protruding from the end faces of these SRC members are joined to each other, and reinforcing bars are arranged between the SRC members, and then , Concrete may be cast to construct a post-cast concrete body. In this case, since air collects at the joint interface between the SRC member and the post-cast concrete body, an injection pipe is inserted between the end face of the SRC member and the post-cast concrete body, and the post-cast concrete body is formed. After curing, the non-shrink grout material is injected into an unfilled portion such as an air retainer formed on the joint interface through the injection pipe (see Patent Documents 1 to 3). However, as in Patent Documents 1 to 3, when the non-shrink grout material is injected through the injection pipe, there is a problem that it takes time and effort and the construction cost increases.

Japanese Patent No. 3396851 Japanese Unexamined Patent Publication No. 2004-011203 Japanese Unexamined Patent Publication No. 2004-190364

An object of the present invention is to propose a concrete rod-shaped member and a concrete rod-shaped member joint structure capable of constructing a joint structure of a steel-framed reinforced concrete member in a short construction period and at low cost.

As a joint structure of concrete rod-shaped members having an SRC structure, the present inventors provided a partially closed steel plate having an upward gradient from the center to the outside on the end face of the concrete rod-shaped members, thereby providing the rod-shaped members to each other. The present invention was made by focusing on the point that when concrete is placed between the two, the number of air bubbles staying at the joint boundary surface can be reduced to form a solid concrete body. Specifically, the present invention is a joint structure of a concrete rod-shaped member made of precast concrete and a concrete rod-shaped member in which the concrete rod-shaped members are joined to each other.

The rod-shaped member of the first invention is a concrete rod-like member including a rod-shaped concrete body (for example, a concrete body 11 described later) and a steel frame core material (for example, a steel frame core material 12 described later) embedded in the concrete body. A member (for example, a concrete rod-shaped member 10 described later), the steel frame core material projects from at least the lower end surface of the concrete body, and at least the lower end surface of the concrete body is a steel plate (for example, the steel frame core material). The steel frame 22), which will be described later, is joined, and the steel plate extends in a direction intersecting the axial direction of the steel frame core material and rises outward from the central portion of the concrete body. ..

Here, the rod-shaped member includes a vertical support member such as a column member or a stud.
According to the present invention, the steel frame core material protrudes from the lower end surface of the concrete body, and on the lower end surface of the concrete body, a steel plate that rises outward from the central portion of the concrete body is joined to the steel frame core material. Therefore, when a concrete body is formed by post-casting under the concrete rod-shaped member, the effect of the gradient of the steel plate reduces the air bubbles that accumulate at the joint interface between the concrete rod-shaped member and the post-cast concrete body, resulting in denseness. A solid concrete body can be formed afterwards.
Further, when the concrete body is formed by post-casting under the concrete rod-shaped member, the air bubbles accumulated in the joint interface between the concrete rod-shaped member and the concrete body of the post-casting can be reduced. Even if the injection agent is not injected into the gap, the unfilled part of the concrete is not formed and a solid post-casting concrete body can be formed. Therefore, the concrete is made of steel-framed reinforced concrete in a short construction period and at low cost. A joint structure of rod-shaped members can be constructed.
Further, the steel plate provided on the end face of the concrete body of the concrete rod-shaped member functions as a formwork material for the concrete body.

The concrete rod-shaped member of the second invention is characterized in that the surface area of the steel plate is smaller than the surface area of the end face of the concrete body, and the steel plate is provided with a plurality of through holes.

According to the present invention, a through hole is provided in a steel plate joined to a steel frame core material to provide an air vent hole for concrete placement in a manufacturing process of a concrete rod-shaped member. Therefore, in the manufacturing process of the concrete rod-shaped member, when the concrete is cast, the air contained in the concrete immediately after the casting is released to the outside of the concrete body through the through hole, so that the air bubbles accumulated on the end face of the concrete rod-shaped member are eliminated. Can be reduced.

The concrete rod-shaped member joining structure of the third invention is a concrete rod-shaped joining structure in which the above-mentioned concrete rod-shaped members arranged one above the other are joined to each other. The steel core members of the concrete rod-shaped members of No. 1 are joined by welding or bolts, and high-fluidity concrete is filled between the upper and lower concrete rod-shaped members.

According to the present invention, the steel core material protruding above the upper end surface of the lower concrete rod-shaped member and the steel core material protruding below the lower end surface of the upper concrete rod-shaped member are joined by welding or bolting. Furthermore, high-fluidity concrete was filled between the concrete bodies of the upper and lower concrete rod-shaped members. As a result, it is possible to realize a joint structure of concrete rod-shaped members in which precast concrete rod-shaped members are firmly joined to each other.
Further, since the concrete rod-shaped member made of precast concrete and the high-fluidity concrete cast on site can be integrated, a joint structure of the concrete rod-shaped member can be constructed in a short construction period and at low cost.

According to the present invention, it is possible to provide a concrete rod-shaped member and a concrete rod-shaped member joint structure capable of constructing a joint structure of a steel-framed reinforced concrete member in a short construction period and at a low cost.

It is a side view of the joint structure of the concrete rod-shaped member which concerns on 1st Embodiment of this invention. It is an enlarged side view of the joint part of the concrete rod-shaped member joint structure. 2A is a cross-sectional view taken along the line AA and FIG. 2B is an arrow view taken along the line BB of the concrete rod-shaped member of FIG. 2 is a schematic view of the lower end surface of the concrete body of the concrete rod-shaped member of FIG. 2 and a schematic view of a vertical cross section of the lower end surface. 2 is a schematic view of a vertical cross section of the upper end surface of the concrete body of the concrete rod-shaped member of FIG. 2 and a modified example of the upper end surface. It is explanatory drawing of the construction procedure of the joint part of the joint structure of the concrete rod-shaped member. It is explanatory drawing of the compressive strength test of concrete. It is sectional drawing of the joint part of the joint structure of the concrete rod-shaped member. It is a schematic diagram of the lower end surface of the concrete body of the concrete rod-shaped member which concerns on 2nd Embodiment of this invention, and the vertical cross section of this lower end surface.

The present invention comprises a concrete rod-shaped member (steel reinforced concrete member) having an SRC structure in which a partially closed steel plate having an upward slope from the center of the cross section is provided on the lower end surface of the concrete rod-shaped member in which the steel core material is embedded. It is a joint structure of concrete rod-shaped members (steel-framed reinforced concrete members) in which the concrete rod-shaped members are joined to each other. The first embodiment of the present invention is a concrete rod-shaped member in which a steel core material is embedded in a rod-shaped concrete body in a cross H-shape or a cross I-shape in which steel materials are welded and joined at a factory (Fig.). 1 to FIG. 6). The second embodiment is a concrete rod-shaped member in which H-shaped steel is embedded inside a rod-shaped concrete body (FIG. 9).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the following embodiments, the same components will be designated by the same reference numerals, and the description thereof will be omitted or simplified.
[First Embodiment]
FIG. 1 is a side view of the joint structure 1 of the concrete rod-shaped member according to the first embodiment of the present invention. FIG. 2 is an enlarged side view of the joint portion (column joint portion 2) of the joint structure 1 of the concrete rod-shaped member. FIG. 3A is a sectional view taken along the line AA of the concrete rod-shaped member 10 of FIG. 2, and FIG. 3B is a view taken along the line BB of the concrete rod-shaped member 10 of FIG.

The joint structure 1 of concrete rod-shaped members is a structure in which precast concrete rod-shaped members 10 arranged one above the other are joined to each other. Here, the joint portion between the upper and lower concrete rod-shaped members 10 is referred to as a column joint portion 2.
The concrete rod-shaped member 10 is made of precast concrete and includes a square columnar (rod-shaped) concrete body 11 having a square cross section extending in the vertical direction, and a steel frame core material 12 and a pillar reinforcing bar 13 embedded in the concrete body 11.

The steel frame core material 12 is a cross-H-shaped steel, and includes four webs 20 arranged in a cross shape and four flanges 21 provided at the outer ends of the webs 20. The steel frame core material 12 projects vertically from the upper and lower end surfaces of the concrete body 11. Through holes 23 are provided in the four webs 20 of the vertically protruding portions of the steel frame core material 12. Further, the steel frame core material 12 may be H-shaped or I-shaped.
The column reinforcing bars 13 are twelve column main bars 30 arranged in a ring shape surrounding the steel frame core material 12 in a horizontal cross-sectional view, and a plurality of bands wound around these column main bars 30 and provided at predetermined intervals in the vertical direction. The muscle 31 and the muscle 31 are provided.

On the lower end surface of the concrete body 11, four steel plates 22 extending in a direction intersecting the axial direction of the steel frame core material, that is, in the horizontal direction are joined to the steel frame core material 12. Specifically, the steel plate 22 is provided in each of the four regions surrounded by the web 20 and the flange 21 of the steel frame core material 12, and the outer edge of each steel plate 22 connects the end edges of the adjacent flanges 21 to each other. I'm out.
Further, each steel plate 22 is provided with a through hole 24. When the concrete of the concrete body 11 of the concrete rod-shaped member 10 is cast at the factory, the steel plate 22 is used as a formwork, and the through hole 24 is used as an air vent hole.

FIG. 4A is a schematic view of the lower end surface of the concrete rod-shaped member 10. FIG. 4B is a cross-sectional view taken along the line CC of the lower end surface of the concrete rod-shaped member 10 of FIG. 4A.
In the lower end surface of the concrete body 11, the portion where the steel sheet is provided with regions A _1. Also, the area A ₂ of the portion excluding the area A ₁ of the square portions steel core is provided. Further, the outer square frame-like part of the portion of the shaped square steel core is provided and the area A _3.
As a result, the total surface area of the four steel plates 22 is smaller than the surface area of the lower end surface of the concrete body.
The region A ₁ is a lower surface of the steel plate 22, the slope rising toward the end from the central portion of the lower end surface of the concrete body is provided. Specifically, the angle α relative to the horizontal plane of the area A _1, or less than 30 degrees 5 degrees.
This angle α was determined by the following procedure. That is, when a vertical load is concentrated on the RC slab via a column or a support member, when the RC slab undergoes punching shear failure, the RC slab has a shear fracture surface having an inclined surface of 30 to 35 degrees. Is known to be formed (F. Leonhardt (Japanese translation): Reinforced concrete design, Kashima Publishing Co., Ltd.). Therefore, the upper limit of the angle α is set to 30 degrees, which is the lower limit of the shear fracture surface, based on the previous knowledge. Further, when the angle α was set to 5 degrees and 10 degrees, it was confirmed by a press-fitting construction test of the column joint portion described later.
In the area A ₂ is a concrete surface is not provided with gradients.
In the area A ₃ is a concrete surface, thus increases the slope toward the end portion side from the center portion of the lower end surface of the concrete body is provided. Specifically, the angle β relative to the horizontal plane in this area A _3, like the region A _1, at most 30 degrees 5 degrees.
Therefore, on the lower end surface of the concrete body 11, as shown in FIG. 4A, the inner region A1 surrounded by the steel frame core material and the outer region A3 of the steel frame core material have an upward slope toward the outside from the center of the cross section. The intermediate region A2 is substantially horizontal.

On the upper end surface of the concrete body 11, as shown in FIG. 5A, four steel plates 22 extending in the horizontal direction are joined to the steel frame core material 12 as in the lower end surface of the concrete body 11. The region A ₁ and the area A ₃ is a concrete surface a steel sheet, the slope rising toward the end from the central portion of the upper end surface of the concrete body 11 is provided. Specifically, the angle α relative to the horizontal plane of the region A ₁ and the area A _3, beta is less than 30 degrees 5 degrees.
In the present embodiment, the steel frame core material 12 is projected from the upper end surface of the concrete body 11, but the present invention is not limited to this, and the steel frame core material may not be projected. Further, in the present embodiment, the steel plate 22 provided on the upper end surface of the concrete body 11 is provided with a gradient that rises from the center to the end of the upper end surface of the concrete body 11, but the present invention is not limited to this. As shown in b), the upper end surface of the concrete body 11 may be a substantially horizontal plane. Alternatively, on the upper end surface of the concrete body shown in FIG. 5, the upper end surface may be formed by using the formwork material without welding the steel plate to the steel frame core material. Specifically, when the upper end surface of the concrete body is made substantially horizontal, it is not necessary to provide the steel plate by casting the concrete of the concrete body using the formwork material.

Returning to FIG. 2, concrete is cast in the column joint 2 by cast-in-place to form a post-cast concrete body 14. In the column joint portion 2, the steel frame core members 12 of the upper and lower concrete rod-shaped members 10 are bolted together. In the present embodiment, the steel frame core members 12 are bolted together, but the present invention is not limited to this, and welding may be used. Further, in the column joint portion 2, the column main bars 30 of the upper and lower concrete rod-shaped members 10 are joined to each other by a mechanical joint, and a band bar 31 is provided.

The column joint portion 2, which is the joint portion of the joint structure 1 of the concrete rod-shaped member, is constructed by the following procedure.
First, as shown in FIG. 2, the steel core members 12 of the upper and lower concrete rod-shaped members 10 are joined by bolt joints or welded joints, and the column main bars 30 and the band bars 31 are arranged at the column joints 2.

Next, as shown in FIG. 6, side formwork 40A, 40B, 40C, 40D covering the four side surfaces of the portion to be the column joint portion 2 is built. At this time, a pressure inlet 41 is provided in the side formwork 40A covering one side surface of the column joint portion 2, and pressure is applied to the side formwork 40C facing the side formwork 40A and the side formwork 40D adjacent to the side formwork 40A. A punch hole 42 is provided.
Here, the height position of the pressure inlet 41 is the intermediate height of the side formwork 40A, and the height position of the pressure release hole 42 is the upper end of the side formwork 40C and 40D.

Next, in this state, high-fluidity concrete is press-fitted into the side formwork 40A to 40D from the press-fitting inlet 41.
High-fluidity concrete has a slump flow (an index indicating the degree of softness of fresh concrete) of 55 cm to 70 cm and a bleeding amount (amount of moisture separated to become a supernatant) of 0.1 cm ³ / cm ² or less.
Further, this press-fitting operation is performed until the concrete overflows from the pressure release hole 42 and the height position of the concrete surface is higher than the lower end surface of the concrete body 11 of the upper concrete rod-shaped member 10. In this way, high-fluidity concrete is filled between the concrete bodies 11 of the upper and lower concrete rod-shaped members 10.

[Compressive strength test of concrete]
Below, an experiment was conducted to verify the relationship between the slope of the steel sheet and the compressive strength of concrete.
First, as shown in FIG. 7A, three cylindrical test bodies 1 to 3 (φ100 mm × height 200 mm) composed of a pre-cast concrete body and a post-cast concrete body are manufactured.
Specifically, first, as shown in FIG. 7B, three cylindrical pre-cast concrete bodies (φ100 mm × height 100 mm) are manufactured. Next, the upper end surfaces of these pre-cast concrete bodies are cut so that the gradient with respect to the horizontal plane is θ. In the test body 1, the gradient θ is 0 degrees, in the test body 2, the gradient θ is 5 degrees, and in the test body 3, the gradient θ is 10 degrees. After that, concrete is cast on the pre-cast concrete body to form a post-cast concrete body.

The compression strength test was performed on the above test pieces 1 to 3. As a result, the compressive strength of Specimen 1 (gradient 0 degrees) was 73.7 N / mm ² , the compressive strength of Specimen 2 (gradient 5 degrees) was 74.3 N / mm ² , and the compressive strength of Specimen 3 (gradient 10 degrees) was 73.7 N / mm 2. The compression strength was 74.1 N / mm ² .
Therefore, the compression strength ratio to the test body 1 (gradient 0 degree) is 1.01 times for the test body 2 (gradient 5 degrees), 1.01 times for the test body 3 (gradient 10 degrees), and the gradient θ is 10. The compressive strengths of the test body 2 and the test body 3 which were not more than the degree were equivalent to the compressive strength of the test body 1 (gradient of 0 degree). Therefore, from the results of the compressive strength test, it was confirmed that it is desirable that the gradient of the steel sheet is more than 0 degrees and 10 degrees or less.

[Press-fitting test of column joint]
A press-fitting construction test of the column joint was conducted under the following conditions.
Column joint size: 850 mm x 850 mm x 1300 mm
Pillar main bar: 12-D35
Reinforcing muscle: D16
Band muscle: D16- □-@ 100mm
Steel core material: SH-550 mm x 200 mm x 12 mm x 25 mm
CT-275 mm x 200 mm x 12 mm x 25 mm

The lower end surface of the concrete body of the concrete rod-angle α of the region A ₁ is a steel plate is 10 degrees, the angle of the area A ₂ is a concrete surface was 0 °. Also, the area A ₃ is a concrete surface and 150mm portion from the outer peripheral surface, and the angle β in this area A ₃ and 5 degrees (see FIG. 4).

Through holes having a diameter of 80 mm were provided in the four webs of the vertically protruding portions of the steel frame core material.
The size of each pressure relief hole provided in the side formwork was 200 mm in width × 80 mm in height.
The side formwork provided with the pressure vent holes was provided with an air vent hole having a diameter of 20 mm at one place, and the side formwork not provided with the pressure vent hole was provided with an air vent hole having a diameter of 20 mm at three places.

As the high-fluidity concrete, a concrete having a water-cement ratio of 31%, a nominal strength of 67, and a slump flow set value of 60 cm (actual measurement value was 58.0 cm × 56.5 cm) was used. Further, the concrete placing speed was set to 5 m ^{3 /} h until the concrete overflowed from the pressure relief hole and the height position of the concrete surface was higher than the lower end surface of the concrete body of the upper concrete rod-shaped member.

When the upper concrete rod-shaped member was removed 12 days after the press-fitting, the result was as shown in FIG. As shown in FIG. 8, the filling rate between AB provided with the pressure inlet was 99.59%, the filling rate between DA provided with the pressure release hole was 99.69%, and the pressure release hole was provided. The filling rate between C and D was 95.56%, and the filling rate between B and C without a pressure relief hole was 97.73%. The total filling rate was 98.15%. Therefore, it was confirmed that the concrete rod-shaped member of the present invention can reduce the amount of air bubbles accumulated at the joint boundary surface between the concrete rod-shaped member and the post-cast concrete body of the column joint. Therefore, it was confirmed that it is desirable that the gradient of the steel sheet is more than 0 degrees and 10 degrees or less from the viewpoint of the filling rate by the press-fitting test of concrete as well as the above-mentioned compressive strength.

According to this embodiment, there are the following effects.
(1) A steel plate 22 having a gradient that rises toward the outside is provided on a portion of the steel frame core material 12 located on the lower end surface of the concrete body 11. Therefore, when the concrete body of the column joint 2 is formed under the concrete rod-shaped member 10 by post-casting, the bubbles accumulated at the joint interface between the concrete rod-shaped member 10 and the post-casting concrete body are reduced to make the concrete body dense. A solid concrete body can be formed. Further, since the steel plate 22 is provided on the steel frame core material 12 on the lower end surface of the concrete body 11 of the concrete rod-shaped member 10, the steel plate 22 functions as a formwork material for the concrete body 11, and the concrete rod-shaped member 10 can be formed in a short construction period. Can be built.
Further, when the concrete body of the column joint 2 is formed under the concrete rod-shaped member 10 by post-casting, air bubbles do not accumulate at the joint interface between the concrete rod-shaped member 10 and the post-casting concrete body, so that the conventional method is used. Even if the injection agent is not injected into the gap of the joint interface, a large unfilled part of concrete is not formed and a solid post-casting concrete body can be formed, so that the construction period is short and the cost is low. The concrete rod-shaped member joint structure 1 can be constructed.

(2) A through hole 24 is provided in the steel plate 22 that closes a part of the steel frame core material 12 to serve as an air vent hole for concrete placement in the manufacturing process of the concrete rod-shaped member. Therefore, in the manufacturing process of the concrete rod-shaped member 10, when the concrete is placed, the air contained in the concrete immediately after the placement is released from the through hole 24 to the outside of the concrete body, so that the end face of the concrete rod-shaped member 10 is covered. The amount of air bubbles that accumulate can be reduced. As a result, it is possible to realize a joint structure of concrete rod-shaped members having excellent structural performance.

(3) The steel frame core material 12 projecting upward from the lower concrete rod-shaped member 10 and the steel frame core material 12 projecting downward from the upper concrete rod-shaped member 10 are bolted together, and further, the lower concrete rod-shaped member is further formed. A pillar joint 2 was constructed by filling high-fluidity concrete between the upper end surface of the concrete body 11 of 10 and the lower end surface of the concrete body 11 of the upper concrete rod-shaped member 10. Thereby, the concrete rod-shaped member joining structure 1 in which the concrete rod-shaped members 10 are firmly joined to each other can be realized.
Further, since the concrete rod-shaped member 10 made of precast concrete and the column joint portion 2 made of high-fluidity concrete cast on site can be integrated, the concrete rod-shaped member joint structure 1 can be constructed in a short construction period and at low cost.

(4) Since the steel plate 22 is joined to the end face of the concrete body 11 of the steel frame core material 12, the steel frame core material is not provided and only the steel frame core material having a uniform cross-sectional shape is embedded in the concrete body. The adhesion strength between the 12 and the concrete body 11 can be increased.

[Second Embodiment]
FIG. 9 is a schematic view of a lower end surface of the concrete body 11 of the concrete rod-shaped member 10A according to the second embodiment of the present invention and a vertical cross section of the lower end surface.
In the present embodiment, the shapes of the steel frame core material 12A and the steel plate 22A are different from those of the first embodiment.
That is, the steel frame core material 12A is an H-shaped steel, and two steel plates 22A extending in the horizontal direction are provided at a portion of the steel frame core material 12A located on the lower end surface of the concrete body 11.
The steel plate 22A is provided with a gradient that rises from the center to the end of the lower end surface of the concrete body 11, and the angle α of the steel plate 22A with respect to the horizontal plane is 5 degrees or more and 10 degrees or less. Specifically, in the lower end surface of the concrete body 11, and A ₁ a portion inwardly of a steel plate of Steel core 12A is provided an H-shaped steel region, an area A ₃ the outer portion of the region A ₁ To do. Region A ₁ and region A ₃ have the same gradient.

According to this embodiment, there is the same effect as the above-mentioned (1) to (3).
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.
For example, in each of the above-described embodiments, the concrete rod-shaped member 10 has a steel-framed reinforced concrete structure in which a column main bar 30 and a band bar 31 are provided on a concrete body 11, but the present invention is not limited to this. For example, the concrete rod-shaped member may be a steel-framed concrete structure in which only the steel core material is provided in the concrete body and the column main bars and the band bars are not arranged, or in addition to the column main bars and the band bars in the concrete body. A prestressed steel-framed reinforced concrete structure in which a tension material is arranged may be used.

1 ... Concrete rod-shaped member joint structure 2 ... Column joint 10, 10A ... Rod-shaped member 11 ... Concrete body 12, 12A ... Steel core material 13 ... Column reinforcing bar 14 ... Concrete body 20 ... Web 21 ... Flange 22, 22A ... Steel plate 23 ... Through hole 24 ... Through hole 30 ... Pillar main bar 31 ... Band reinforcement 40A, 40B, 40C, 40D ... Side formwork 41 ... Pressure inlet 42 ... Pressure release hole

Claims (3)

A concrete rod-shaped member including a rod-shaped concrete body and a steel frame core material embedded in the concrete body.
The steel frame core material projects from at least the lower end surface of the concrete body.
At least on the lower end surface of the concrete body, a steel plate is joined to the steel frame core material.
The steel plate is a concrete rod-shaped member that extends in a direction intersecting the axial direction of the steel frame core material and rises outward from the central portion of the concrete body. The surface area of the steel plate is smaller than the surface area of the end face of the concrete body.
The concrete rod-shaped member according to claim 1, wherein the steel plate is provided with a plurality of through holes. A concrete rod-shaped joint structure in which the concrete rod-shaped members according to claim 1 or 2 arranged one above the other are joined to each other.
The concrete rod-shaped member is made of precast concrete and is made of precast concrete.
The steel core materials of the upper and lower concrete rod-shaped members are joined by welding or bolts.
A joint structure of concrete rod-shaped members, characterized in that high-fluidity concrete is filled between the upper and lower concrete rod-shaped members.

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