JP3988884B2 - Reinforced concrete members - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforced concrete member, and more particularly, to a reinforced concrete member having a shear reinforcement.
[0002]
[Background]
In the columns and beams of reinforced concrete members, shear reinforcement bars are usually arranged around the main bars to reinforce the shear plane of the reinforced concrete members. As such a shear reinforcing bar of a reinforced concrete member, there is, for example, one in which a cross-sectional shape is formed into a flat shape and the bar is arranged around the main bar with the flat surface inside (for example, Patent Document 1). According to this configuration, since the bending work of the shear reinforcement bars becomes easier than the conventional shear reinforcement bars with a circular cross section, the bar arrangement work such as wrapping around the main bars becomes easy and the workability is improved. be able to.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-229071 (Page 2, FIGS. 1 and 5)
[0004]
[Problems to be solved by the invention]
By the way, when a high compressive axial force is applied to the reinforced concrete member, the shear reinforcing bar restrains the main bar and the concrete in a direction orthogonal to the axial direction to prevent buckling of the main bar and the concrete on the bending compression side.
However, for example, when a reinforced concrete member undergoes a large deformation due to an earthquake or the like, cracks or the like may occur in the concrete, and the concrete around the main reinforcement and the shear reinforcement may be peeled off. In this case, it is only the shear reinforcement that restrains the core concrete or the main reinforcement from protruding outward, and the yield strength of the reinforced concrete member is greatly influenced by the bending rigidity in the direction perpendicular to the material axis of the shear reinforcement.
[0005]
However, since the shear reinforcing bars having the flat cross section as described above are arranged around the main bars so that the flat plane is inside, the bending rigidity in the direction orthogonal to the material axis direction is higher than that of the conventional circular one. However, it becomes weaker and sufficient bending rigidity cannot be obtained, and sufficient proof strength of the reinforced concrete member cannot be secured.
[0006]
An object of the present invention is to provide a reinforced concrete member capable of improving yield strength and deformation performance.
[0007]
[Means for Solving the Problems]
The reinforced concrete member of the present invention includes a main reinforcing bar arranged along a material axis of the reinforced concrete member, and a shear reinforcing bar arranged around the main reinforcing bar, and the shear reinforcing bar bends a rod-shaped member made of steel. It is to form the cross-sectional shape of the shear reinforcement has a substantially elongated shape having a major axis and a minor axis, said major axis are arranged along a direction perpendicular to the material axis Features.
In the present invention having this configuration, since the cross-sectional shape of the shear reinforcing bar is formed in a substantially elongated shape, the bending rigidity related to the short axis is higher than the bending rigidity related to the long axis. In this case, since the major axis is arranged along the direction perpendicular to the material axis direction, the longitudinal axis is related to the direction perpendicular to the major axis as compared with a conventional shear flat bar having a cross-sectional area or a circular cross-section. The bending rigidity is improved, the confining effect by the shear reinforcement is increased, and the yield strength and deformation performance of the reinforced concrete member are improved.
[0008]
Here, a reinforced concrete member means a concrete member reinforced with a reinforcing bar. In addition to a reinforced concrete in which the periphery of a so-called reinforcing bar made of reinforcing steel is solidified with concrete, the surrounding area is a reinforced concrete structure. It also includes so-called steel reinforced concrete.
The reinforced concrete member includes a shaft-like member having a predetermined length such as a column or a beam, and the material axis direction of the reinforced concrete member means a direction along the length direction.
Note that the cross-sectional shape of the shear reinforcement is an elongated shape means that the dimension in the direction perpendicular to the material axis is longer than the dimension in the other direction, for example, approximately rectangular, elliptical, isosceles Various shapes such as a triangle can be adopted.
[0009]
In the present invention, the cross-sectional shape of the shear reinforcement is substantially rectangular, and when the length of the short side is 1, the length of the long side is set to 1.2 or more, and the long side is the material. It is desirable to arrange | position along the direction orthogonal to an axial direction.
In the present invention having this configuration, since the cross-sectional shape of the shear reinforcing bar is formed in a simple substantially rectangular shape, the molding becomes simple and the manufacturing of the shear reinforcing bar becomes easy. Moreover, since the cross-sectional shape of the shear reinforcing bar is substantially rectangular, when the long side is arranged along the direction perpendicular to the material axis direction, the short side is substantially parallel to the axial direction of the main bar. Therefore, if the short side is arranged in contact with the main bar, the long side is arranged in a predetermined direction, so that the work of arranging the reinforcing reinforcing bars becomes easy. Furthermore, by arranging the short side in contact with the main reinforcement, the shear reinforcement is stably arranged, and the bending rigidity of the shear reinforcement is improved more reliably.
[0010]
In addition, since the cross-sectional shape of the shear reinforcement is set so that the length of the long side becomes 1.2 or more when the length of the short side is 1, the cross-sectional secondary moment of the shear reinforcement is the same. Compared to a shear reinforcing bar having a circular cross section, the bending rigidity is improved by about 1.5 times or more. Thereby, the confinement effect by a shear reinforcement becomes remarkable and the yield strength and deformation performance of a reinforced concrete member improve further. In addition, when the length of the long side is smaller than 1.2, the improvement of the cross-sectional secondary moment of the shear reinforcement becomes small, and the remarkable improvement in bending rigidity cannot be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a reinforced concrete member 1 according to an embodiment of the present invention. In FIG. 1, a reinforced concrete member 1 is a column having a rectangular cross section along a material axis direction A, and a concrete 2 (illustrated by a two-dot chain line) formed in a substantially rectangular cross section and disposed in the concrete 2. A reinforced bar 3 is provided.
[0012]
A plurality of (8 in this embodiment) main bars 31 are arranged along the material axis direction A, and the reinforcing bar rod 3 is a shear arranged around these main bars 31 in a direction substantially perpendicular to the material axis direction A. Reinforcing bars 32 are provided.
As shown in FIG. 2, the main reinforcing bars 31 are deformed reinforcing bars having discontinuous hump-like nodes, and are arranged at equal intervals in three vertical and horizontal directions on a virtual rectangle having a predetermined distance from the outer end of the concrete 2. Yes. In addition, although these main reinforcements 31 may be comprised with the round steel, adhesiveness with the concrete 2 becomes favorable by having a node. Further, the diameter d of the main reinforcing bar 31, the distance w from the adjacent main reinforcing bar 31, and the number of arrangements are appropriately set in consideration of the dimensions of the reinforced concrete member 1, the material of the main reinforcing bar 31, usage conditions, and the like.
[0013]
The shear reinforcement bars 32 are formed in a substantially rectangular ring shape by bending a rod-like member and welding the end portions, and a plurality of the shear reinforcement bars 32 along the material axis direction A have a predetermined interval h. It is arranged on the outer side of the main muscle 31. The cross-sectional shapes of these shear reinforcement bars 32 are formed in a substantially rectangular shape having a short side 32A and a long side 32B as shown in FIG. The short side 32 </ b> A is arranged in parallel with the material axis direction A and is in contact with the outer periphery of the main bar 31. Accordingly, the long side 32B is arranged along a direction orthogonal to the material axis direction A. The portions where the shear reinforcement bars 32 and the main bars 31 intersect are bound together.
[0014]
Here, the dimensions L and M of the short side 32A and the long side 32B of the shear reinforcement bar 32 are appropriately set in consideration of the dimension of the reinforced concrete member 1, the dimension d of the main bar 31, the arrangement interval w, and other use conditions. The Specifically, the dimensions L and M of the shear reinforcement 32 are set so that the bending rigidity of the shear reinforcement 32 is appropriate when a load is applied from a direction parallel to the long side 32B, and the dimension M is the dimension. It is desirable that it is 1.2 times or more of L. Alternatively, the dimensions L and M may be set so that the shear reinforcement ratio of the shear reinforcement 32 is appropriate in consideration of the dimensions of the reinforced concrete member 1 and the like.
Moreover, the arrangement | positioning space | interval h and the number of arrangement | positioning of the some shear reinforcement 32 are also set suitably so that the reinforced concrete member 1 can ensure appropriate intensity | strength.
[0015]
The reinforcing bars of the shear reinforcing bars 32 are not limited to being formed in an annular shape, and can be arbitrarily set such as a stirrup or a spiral line. In this case as well, the spacing of the stirrup and spiral muscles can be set as appropriate. In the case of using a spiral line, the winding angle and the number of windings of the main bar 31 can be appropriately set.
Further, the shear reinforcing bar 32 may have a node. In this case, the surface area is increased by the nodes, the adhesion to the concrete 2 becomes stronger, and the proof strength of the reinforced concrete member can be further improved.
[0016]
In such a reinforced concrete member 1, first, in a factory, main bars 31 are arranged at equal intervals on a virtual rectangle, and shear reinforcement bars 32 are arranged on the outer periphery thereof. Then, the reinforcing bar 3 is formed by binding the intersection of the main reinforcing bar 31 and the shear reinforcing bar 32. The reinforcing bar 3 may be formed at a construction site.
The reinforcing bar 3 is transported to the construction site and installed at a predetermined position, and a formwork is attached around the reinforcing bar 3 and concrete is placed. After the concrete is hardened, the formwork is removed to complete the reinforced concrete member 1.
In the reinforced concrete member 1 manufactured as described above, the inner side and the outer side of the main reinforcing bar 31 and the shear reinforcing bar 32 are filled with the concrete 2 as shown in the sectional view of FIG. At this time, the dimension of the formwork is set in advance so that the distance from the outer end face of the shear reinforcement bar 32 to the end face of the outer shape of the reinforced concrete member 1, that is, the covering thickness t of the concrete 2 becomes a predetermined dimension. .
[0017]
When an axial force such as a compression axial force is applied to such a reinforced concrete member 1 in a direction along the material axis direction A, a shearing force acts on a plane orthogonal to the material axis direction A. At this time, since the shear reinforcement bar 32 restrains the main bar 31 and the concrete 2 in the shear plane direction, the reinforced concrete member 1 is reinforced in the direction and the buckling of the reinforced concrete member 1 is prevented.
Further, when the reinforced concrete member 1 is greatly deformed due to an earthquake or the like and the concrete 2 outside the reinforcing bar 3 is partly peeled off, the inside of the main reinforcing bar 31 is restrained by the concrete 2, but the outside is not restrained. The binding force becomes weak, and the main reinforcement 31 and the concrete 2 (that is, core concrete) surrounded by the main reinforcement 31 tend to protrude outward as indicated by the arrows in FIG. Even in such a case, the shear reinforcing bar 32 restrains the main bar 31 to prevent the main bar 31 from being deformed and prevent the reinforced concrete member 1 from buckling or protruding.
[0018]
According to such a reinforced concrete member 1, the following effects are obtained.
(1) Since the cross-sectional shape of the shear reinforcement bar 32 is formed in a substantially rectangular shape, the bending rigidity related to the short side 32A can be improved as compared with a circular shear reinforcement bar having the same cross-sectional area. Therefore, by arranging the long side 32B along the direction orthogonal to the material axis direction A, the bending rigidity of the shear reinforcing bar 32 in the direction can be improved, and the connection of the reinforced concrete member 1 by the shear reinforcing bar 32 can be improved. The find effect can be enhanced. Moreover, this can improve the yield strength and deformation performance of the reinforced concrete member 1, and can make a concrete member generally said to be brittle.
[0019]
(2) Since the cross-sectional shape of the shear reinforcement bar 32 is formed in a simple substantially rectangular shape, it can be easily manufactured, and an increase in the manufacturing cost of the shear reinforcement bar 32 can be prevented. Further, if the short side 32A is brought into contact with the side surface of the main bar 31, the long side 32B can be arranged in a direction orthogonal to the material axis direction A. Therefore, the shear reinforcing bar 32 can be easily arranged in a predetermined direction, and the bar arrangement work is performed. Easy to do. Furthermore, since the short side 32A contacts the main reinforcement 31 linearly, the shear reinforcement 32 can be stably arranged.
[0020]
The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
The cross-sectional shape of the shear reinforcement is not limited to a substantially rectangular shape, and any arbitrary shape can be adopted as long as it is an elongated shape having a major axis and a minor axis. For example, an elliptical shape as shown in FIG. 5 (A), a triangular shape as shown in FIG. 5 (B), a trapezoidal shape as shown in FIG. 5 (C), and the like are shown in FIG. 5 (D). A polygonal shape such as an octagonal shape may be set as appropriate.
At this time, in any case, if the major axis B is arranged along the direction orthogonal to the material axis direction, the axis is parallel to the material axis direction compared to the shear reinforcing bar having the same area and a circular cross section. Since the bending rigidity can be improved, the object of the present invention can be achieved.
[0021]
That is, if the cross-sectional shape of the shear reinforcement is formed so that the bending rigidity in the direction parallel to the material axis direction is higher than the bending rigidity in the direction orthogonal to the material axis direction, for example, the shear of the same cross-sectional area Even with reinforcing bars, the rigidity can be improved efficiently only in the direction that requires high bending rigidity.
At this time, the shear reinforcement is not limited to a single material made of a solid material, and a desired shape is integrally formed by, for example, welding a plurality of square shear reinforcements. May be. In this case, the cross-sectional secondary moment can be increased by changing the cross-sectional shape to an approximately elongated shape by welding or the like to the existing shear reinforcement, thereby improving the proof strength of the existing reinforced concrete.
[0022]
The arrangement of the shear reinforcement bars is not limited to the one arranged outside the main bars, and may be arranged inside the main bars, or may be arranged both outside and inside the main bars. Further, a plurality of shear reinforcement bars may be bundled and arranged outside or inside the main bar.
The bar arrangement of the main bars is not limited to a rectangular arrangement, and can be set as appropriate in consideration of the application, load direction, dimensions, etc., such as a circular shape or a deformed shape.
Thus, the reinforcement of the main reinforcement and the shear reinforcement can be appropriately set in consideration of the use conditions of the reinforced concrete member.
[0023]
The reinforced concrete member is not limited to the pillar, and may be used as a beam arranged in the horizontal direction, for example. Even in this case, if the cross-sectional shape of the shear reinforcement is appropriately set and the long side is arranged along the direction orthogonal to the direction of the material axis, the bending rigidity of the shear reinforcement is improved and the confined reinforced concrete member is improved. An effect can be heightened and the yield strength of a beam can be improved. Therefore, it is possible to satisfactorily prevent the bending of the main bar on the bending compression side and the protruding behavior of the core concrete even by the bending load of the beam.
In addition, the cross-sectional shape of the reinforced concrete member is not limited to a rectangular shape, and can be appropriately set in consideration of the use and use conditions such as a circular shape and an elliptical shape.
[0024]
Although the best configuration, method and the like for carrying out the present invention have been disclosed in the above description, the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.
[0025]
【Example】
In order to confirm the effect of the present invention, the following experiment was conducted.
(Example)
A shear reinforcing bar 32 having a rectangular cross section, a dimension L of the short side 32A of about 6 mm, and a dimension M of the long side 32B of about 12 mm was manufactured. At this time, if the length of the short side 32A of the shear reinforcing bar is 1, the length of the long side 32B is about 2.0 (that is, the flatness ratio is 2.0). The material properties of the shear reinforcement 32 are a yield strength of 796 N / mm ² , a yield strain of 4078 × 10 ⁻⁶ , and a Young's modulus of 2.12 × 10 ⁵ N / mm ² . This shear reinforcement bar 32 is arranged together with the main bar 31 in a rectangular concrete 2 having a sectional outer dimension of 300 mm × 200 mm and a height of 700 mm. The interval h between the shear reinforcement bars 32 in the axial direction of the reinforced concrete member 1 is 100 mm, and the reinforcement ratio of the shear reinforcement bars 32 of the reinforced concrete member 1 is 0.0096.
[0026]
(Comparative example)
The cross-sectional area of the shear reinforcement bar 32 is formed in a circular cross section having a radius of about 9.6 mm so that the cross-sectional area of the shear reinforcement bar 32 is substantially the same as that of the embodiment. The material properties of the shear reinforcement 32 are yield strength of 814 N / mm ² , yield strain of 4451 × 10 ⁻⁶ and Young's modulus of 2.10 × 10 ⁵ N / mm ^2, which are almost the same as those of the embodiment. Other conditions are the same as in the examples.
[0027]
(Results of Examples and Comparative Examples)
The results are shown in FIG. FIG. 6 is a diagram illustrating a member deformation angle with respect to an input shear force applied to the reinforced concrete member 1. The diagram shown by the solid line is the reinforced concrete member 1 in the example, and the diagram shown by the dotted line is the reinforced concrete member 1 in the comparative example.
In the example, the maximum shear strength (input shear force at points P and Q in FIG. 6) was about 1.2 times that of the comparative example. Also, from the member deformation angles at points P and Q in FIG. 6, the deformation performance of the example was about 1.75 times that of the comparative example.
From the above, it was possible to confirm the effect of the present invention that the bending rigidity of the shear reinforcing bars can be increased to improve the proof concrete yield strength and deformation performance.
[0028]
【The invention's effect】
According to the present invention, the cross-sectional shape of the shear reinforcement bar is formed into an elongated shape having a major axis and a minor axis, and the major axis is arranged along a direction perpendicular to the material axis direction of the reinforced concrete member. Therefore, the bending rigidity of the shear reinforcing bar in the direction orthogonal to the material axis direction can be improved, and the yield strength of the reinforced concrete member can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a reinforcing bar of a reinforced concrete member according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing a shear reinforcing bar of a reinforced concrete member according to an embodiment of the present invention.
FIG. 3 is a partial cross-sectional view of a reinforced concrete member according to an embodiment of the present invention.
FIG. 4 is a plan sectional view of a reinforced concrete member according to one embodiment of the present invention.
FIG. 5 is a view showing a modification of the reinforced concrete member of the present invention.
FIG. 6 is a diagram showing experimental results in a comparative example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reinforced concrete member, 2 ... Concrete, 3 ... Reinforcement rod, 31 ... Main reinforcement, 32 ... Shear reinforcement, 32A ... Short side, 32B ... Long side.

Claims (2)

A main bar arranged along the axis of the reinforced concrete member;
A shear reinforcement bar arranged around the main bar,
The shear reinforcement is formed by bending a rod-shaped member made of steel,
The cross-sectional shape of the shear reinforcement is formed in a substantially elongated shape having a major axis and a minor axis,
The long axis is disposed along a direction orthogonal to the material axis direction. In the reinforced concrete member according to claim 1,
The cross-sectional shape of the shear reinforcement is substantially rectangular, and when the length of the short side is 1, the length of the long side is set to be 1.2 or more, and the long side is the material axis. A reinforced concrete member, characterized by being disposed along a direction orthogonal to the direction.

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