JP6434853B2 - Design method of reinforced concrete structure and reinforced concrete structure - Google Patents

Description

  The present invention relates to a reinforced concrete structure design method for designing a reinforced concrete structure having a column-beam joint between a column and a beam, and a reinforced concrete structure designed by the design method.

In order to design a reinforced concrete structure, the cross section for the beam bending is calculated based on the bending moment for design. The cross section is calculated as a cross section of the reinforcing bar from the relationship between the bending moment, the allowable tensile stress level of the reinforcing bar, the stress center distance of the beam, and the effective cause of the beam (Non-Patent Document 1).
The reinforcing bar cross-sectional area in Non-Patent Document 1 is the total value of the cross-sectional areas of the main bars for a plurality of beams. The sum of the cross-sectional areas of the main bars for a plurality of beams is converted as the number of reinforcing bars for the number of main bars for the beam.
In a general reinforced concrete structure, the design bending moment is maximized at the base of the beam. Therefore, the diameter and the number of the main bars for the beam are calculated based on the magnitude of the design bending moment of the base.

Reinforced concrete structure calculation criteria and explanation (The Architectural Institute of Japan, February 20, 2010, 8th edition, first print), pages 14 to 16

As shown in Non-Patent Document 1, the rebar cross-sectional area is calculated based on the design bending moment, and is generally set so that the base of the beam becomes a yield hinge. Based on the magnitude of the bending moment for design of the root, the diameter and number of the main bars for the beam are calculated, so if the bending moment of the root is large, If the strength of the main bars for each beam is the same, a large number of main bars for beams or a main bar having a large diameter may be required.
However, if the number of main bars for the beam cannot be increased, either the beam width can be increased or the beam can be increased to reduce the amount of the main bar, and the cross-sectional area of the beam or column beam joint can be increased. There is a problem that must be increased.

In order to solve this problem, the main bar for the beam is configured to include a normal strength portion and a high strength portion having a strength higher than that of the normal strength portion, and the high strength portion is a column beam of the main bars for the beam. Placed continuously from the joint and the high-strength region along the beam length from the beam-to-column joint, and the normal strength part is located on the opposite side of the beam-to-column joint across the high-strength region When calculating the amount of reinforcing bars of the main bars for the beam and the bending moment at the position of the yield hinge as the design bending moment, the position of the yield hinge is the boundary between the high strength part and the normal strength part. It is conceivable to set to
However, in buildings where the position of the yield hinge is set at the boundary between the high-strength part and the normal-strength part, it yields at the normal-strength part, so it is mainly formed continuously from the position where the yield hinge is set to the beam center side. There arises a problem that fracture such as cracking proceeds in the normal strength portion.
This problem also occurs in buildings where the main bars have uniform strength over the entire length, and buildings where the high-strength portions are arranged only at the column beam joints and the beams do not have a high-strength region. In these buildings, the base of the beam-column joint becomes a yielding hinge, and in the normal strength part, there is a possibility that destruction such as cracks progresses from the base toward the center of the beam.

  An object of the present invention is to provide a design method for a reinforced concrete structure and a reinforced concrete structure in which fractures such as cracks are less likely to proceed from the setting position of the yield hinge toward the center of the beam.

  The method for designing a reinforced concrete structure of the present invention includes a plurality of main bars for beams to be joined to a column, and the main bars for the beams have a normal strength portion and a strength higher than that of the normal strength portion. A method of designing a reinforced concrete structure having high strength portions arranged adjacent to each other, wherein the high strength portion includes at least a column beam joint portion joined to the column among the main bars for the beam. It is arranged in the side region and the beam center side region located on the opposite side of the beam-column joint with the normal strength portion interposed therebetween, and the reinforcing bar amount of the main reinforcement for the beam is set to the bending moment at the position of the yield hinge. In calculating the design bending moment, the position of the yield hinge is set at the boundary between the joint-side region and the normal strength portion in the high strength portion.

In the present invention having the above-described configuration, the high-strength portion is disposed in the joint-side region, and the normal-strength portion is disposed adjacent to the high-strength portion. That is, the position of the yield hinge was set to a position away from the beam-column joint, and the portion that limited the position of the yield hinge (destructive region) was set as the normal strength portion.
In the present invention, when a large load such as an earthquake occurs in a reinforced concrete structure, the force concentrates on the boundary portion between the high strength portion and the normal strength portion. In the present invention, the high-strength portion is arranged not only in the joint side region but also in the beam central side region even if the fracture concentrates on the boundary portion and cracks or the like try to diffuse toward the beam central side. Therefore, the diffusion of destruction toward the beam center side is suppressed.
Therefore, in the present invention, when a large earthquake or the like occurs, the main bar for the beam can be surely broken between the joint-side region constituting the high strength portion and the normal strength portion.
Moreover, in the present invention, the position where the yield hinge is set can be controlled from the base of the beam-column joint to a predetermined position in the beam length direction. In other words, when the length of the beam is long, the joint side area is positioned far from the base of the beam-column joint, and when the length of the beam is short, the joint side area is shifted from the base of the beam-column joint. Close position. This increases the degree of freedom in designing reinforced concrete structures.

In the reinforced concrete design method of the present invention, the dimension in the beam length direction between the boundary position between the joint-side region and the boundary position between the beam center-side region of the normal strength portion is 100 mm or more. A configuration that is less than or equal to the length of the beam is preferable.
By securing the above-mentioned dimensions, it is possible to suppress the breakage of the beam from progressing to the beam-column joint when a large earthquake or the like occurs, and to reliably break the main bar for the beam.

In the method for designing a reinforced concrete structure according to the present invention, it is preferable that a portion having a small bending moment at the center of the main reinforcing bars for the beam has a normal strength.
In this configuration, the manufacturing cost can be reduced by setting the normal strength portion on the center side of the beam other than the position where the yield hinge is set. In other words, the center side of the beam on the opposite side across the beam center side region where the yield hinge is set does not need to be a high-strength portion because the bending moment at the center is small. Therefore, the manufacturing cost of the main bar can be suppressed by minimizing the area set in the high-strength portion.

In the design method of the reinforced concrete structure of this invention, the structure by which the through-hole for equipment piping is provided in the said high intensity | strength part is preferable.
In this structure, since the area | region in which the through-hole for equipment piping is provided is high intensity | strength, even if it constructs the hole for equipment piping, the strength fall of a building can be made small.

In the method for designing a reinforced concrete structure of the present invention, the joint side region is formed to be continuous with the first region disposed in the column beam joint and the first region, and the beam length from the column beam joint. A second region along the direction, wherein the facility piping through-hole includes a first through-hole disposed in the second region and a second through-hole disposed in the beam center side region. Is preferred.
In this configuration, since the first through hole and the second through hole are arranged across the normal strength portion where the yield hinge is set, it is possible to easily perform the construction work of the plurality of facility pipes.

In the reinforced concrete design method of the present invention, the normal strength portion has a yield point or 0.2% yield strength defined by JIS G3112, and the high strength portion has a yield point or 0.2% yield strength greater than the normal strength portion. It is preferable that the main reinforcing bar for the beam is a structure in which one normal reinforcing bar having the same strength as that of the normal strength portion is partially quenched to form the high strength portion.
In this configuration, a normal strength portion and a high strength portion are formed by partially quenching one ordinary rebar with a yield point or 0.2% proof stress specified in JIS G3112. It is not necessary to increase the thickness of the high strength part. Therefore, also from this point, it is not necessary to increase the cross-sectional area of the column beam joint. Moreover, since the normal strength portion and the high strength portion are composed of a single reinforcing bar, handling on the site is facilitated.

In the design method of the reinforced concrete structure of this invention, the structure where the thickness of the said high strength part is thick with respect to the thickness of the said normal strength part is preferable.
Since the thickness of the reinforcing bar is proportional to the strength, if the thickness of the reinforcing bar is large, the strength of the reinforcing bar itself becomes large. Therefore, since the strength and the diameter of the high strength portion are larger than those of the normal strength portion, the difference in strength with respect to the normal strength portion can be made larger.

In the method for designing a reinforced concrete structure of the present invention, the normal strength portion and the high strength portion are connected to each other through end portions facing each other, and the joint portion includes friction welding, gas pressure welding, and welding. The structure formed by either is preferable.
In this configuration, the joining portion is formed by friction welding, gas welding, or welding, so that the portion where the normal strength portion and the high strength portion are abutted is swollen. This swollen portion can increase the adhesion with concrete.

In the method for designing a reinforced concrete structure of the present invention, the normal strength portion and the high strength portion are connected to each other through end portions facing each other, and the joint portion is formed in the normal rebar portion. A configuration having a coupler screwed into the male screw portion and the male screw portion formed in the high-strength portion is preferable.
In this configuration, a small-diameter rebar and a large-diameter rebar are joined using a coupler, so compared with the case where a joint is formed by friction welding, gas welding, or welding, the large-diameter rebar and the small-diameter rebar at the construction site are connected. Connection work becomes easy.

In the method for designing a reinforced concrete structure of the present invention, the normal strength portion and the high strength portion are connected to each other through end portions facing each other, and the joint portion is formed in the normal rebar portion. A configuration having a male screw part and a female screw part screwed into the male screw part and formed in the high-strength part is preferable.
In this configuration, a coupler is not required to join the normal strength part and the high strength part, so it is not only easy to work on site, but there is no need to prepare a separate coupler. Management during construction becomes easier.

The reinforced concrete structure of the present invention is characterized by being designed by the method for designing a reinforced concrete structure having the above-described configuration.
With this configuration, the same effects as described above can be obtained.

Schematic of the concrete structure concerning 1st Embodiment of this invention. (A) is a moment distribution diagram showing the relationship between the position of the main bar and the design bending moment, (B) is a schematic front view of the main bar, and (C) is a schematic cross-sectional view of the main bar. (A) is a schematic diagram of the cracked state of the beam of the first embodiment, (B) is a graph showing the relationship between the adhesion length of the main reinforcement for the beam and the stress distribution. (A) is a schematic diagram of the crack state of the beam of a prior art example, (B) is a graph which shows the relationship between the adhesion length of the main reinforcement for beams, and stress distribution. The figure which shows 2nd Embodiment of this invention, and is a figure corresponded to FIG. 2 (A) (B). The figure which shows 3rd Embodiment of this invention and is equivalent to FIG. The 4th Embodiment of this invention is shown, (A) to (C) is the schematic which shows the procedure which forms a junction part. (A) to (C) is a schematic diagram showing a procedure for forming different joints. (A) to (C) is a schematic diagram showing a procedure for forming further different joints. Sectional drawing which shows the principal part of the reinforcing bar structure concerning 5th Embodiment of this invention. (A) is a front view showing a coupler, (B) is an end view of the coupler. Sectional drawing of a coupler. The figure which shows the principal part of the reinforcing bar structure concerning 6th Embodiment of this invention, and is equivalent to FIG.

Embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
1st Embodiment of this invention is described based on FIG.1 and FIG.2 of drawing.
FIG. 1 shows the overall configuration of the first embodiment.
In FIG. 1, the building is a multi-storey reinforced concrete structure including a plurality of beams 2 and a plurality of columns 3 joined to the beams 2, and a concrete body 100 is placed on the reinforced structure 1.
As a form of the beam-to-column joint 200 in which the beam 2 and the column 3 are joined, there are a cross-shaped joint S1 and a to-shaped joint S2, but in the present embodiment, it may be applied to other joints.

The reinforcing bar structure 1 of the beam 2 includes a plurality of beam main bars 21 extending in the horizontal direction, and the bars are arranged at equal intervals so as to surround the main bar 21 in a plane intersecting the axial direction of the main bar 21. A plurality of beam reinforcing bars 22 for reinforcing the shear strength 2.
The main bars 21 adjacent in the horizontal direction are joined by the joint 4. The joint 4 may be a mechanical joint or another joint. Alternatively, the end portions may be overlapped and connected with a wire or the like. Furthermore, the structure which abuts end parts and joins by welding etc. may be sufficient.
The reinforcing bar structure 1 of the pillar 3 surrounds the reinforcing bar 31 in a plane intersecting with the axial direction of the reinforcing bars 31 and a plurality of reinforcing bars 31 for the pillars extending in the vertical direction and arranged at predetermined intervals. There are provided a plurality of column shear reinforcement bars 32 that are arranged at equal intervals in the extending direction of the reinforcing bars 31 and reinforce the shear strength of the columns 3. The reinforcing bar 31 and the shear reinforcing bar 32 are ordinary reinforcing bars.
In addition, since FIG. 1 shows the outline of this embodiment, the number and arrangement | sequence of the main reinforcement 21 and the reinforcing bar material 31 differ from FIG.2 (B) mentioned later.

In the region including the cruciform joint S1, the main muscle 21 has a first high-strength portion 211A at the central portion thereof, and normal strength portions 212 at both ends of the first high-strength portion 211A, respectively. There is a second high-strength portion 211B on the opposite side of the first high-strength portion 211A.
The first high-strength portion 211A is arranged in the first region 210S arranged in the cruciform joint S1 and the second region 210A as a high-strength region along the beam length direction from the cruciform joint S1.
The dimension along the beam length direction of the second region 210A is set according to the dimension between the adjacent pillars 3, the size of the entire building, and other conditions.
For example, when the length of the beam is long, the edge of the second region 210A in the joint side region 21M is positioned far from the root R of the cross-shaped joint S1, and when the length of the beam is short, The two regions 210A are positioned closer to the base R of the cross joint S1.

The normal strength portion 212 is disposed in a normal strength region 210B located on the opposite side of the cruciform joint S1 across the second region 210A. The second high-strength portion 211 </ b> B is disposed on both ends of one main muscle 21.
That is, the high-strength portion is located on the opposite side of the cross-shaped joint S1 with the normal-strength portion 212 sandwiched between the joint-side region 21M located in the cross-shaped joint S1 and the second region 210A in the main bar 21 for the beam. It arrange | positions to the beam center side area | region 21N located.

The beam 2 is provided with a through hole H for equipment piping.
The through-hole H for equipment piping includes a first through-hole H1 provided through the second region 210A in the horizontal direction, and a second through-hole H2 provided through the beam center side region 21N in the horizontal direction. Have The first through hole H <b> 1 and the second through hole H <b> 2 are respectively disposed close to the normal strength portion 212.
The 1st through-hole H1 and the 2nd through-hole H2 let the piping for ventilation (not shown) pulled out from the kitchen, the piping which lets an electric wire pass, and other equipment piping, respectively.
The opening shapes of the first through hole H1 and the second through hole H2 are circular in the drawing. In the present embodiment, the opening shapes of the first through hole H1 and the second through hole H2 are not limited to circular holes, and may be rectangular holes or rectangular shapes. The magnitude | size of the 1st through-hole H1 and the 2nd through-hole H2 is restrict | limited to the dimension between the upper and lower beams 2, and the arrangement position of the shear reinforcement 22 mentioned later.

In this embodiment, the reinforcement of the through hole H for equipment piping follows the “Reinforced Concrete Structural Calculation Standards / Same Explanation” (8th Edition, February 20, 2010, Architectural Institute of Japan).
In other words, when a through hole for equipment piping is formed in a reinforced concrete beam, the structural performance of the beam, particularly the ultimate shear strength, is lowered. Further, since cracks due to stress concentration are likely to occur around the outer periphery of the hole, it is necessary to appropriately reinforce the periphery of the hole. Therefore, the first through-hole H1 and the second through-hole H2 constituting the equipment pipe through-hole H have a diameter of the circular hole and a side length of the rectangular hole in the beam direction of 1/3 or less, respectively. When two or more circular holes are provided in the same beam, it is desirable that the center interval of the circular holes be three times or more the hole diameter.
It is preferable not to provide the first through hole H1 and the second through hole H2 in a region where the yield hinge of the beam is provided or in a position eccentric in the beam direction.
It is preferable to reinforce the periphery of the first through hole H1 and the second through hole H2. As a reinforcement against shear, there is a method using a stirrup or an oblique reinforcement. As the reinforcing bars, reinforcing bars surrounding the first through hole H1 and the second through hole H2, for example, Super Harry Z (trade name of Kurimoto Iron Works) may be used.

The first high-strength portion 211A, the normal strength portion 212, and the second high-strength portion 211B are integrally formed from a single reinforcing bar.
The normal strength portion 212 has a yield point or 0.2% yield strength defined by JIS G3112.
The first high-strength portion 211A and the second high-strength portion 211B are stronger than the normal strength portion 212.
For example, the yield point or 0.2% proof stress of the first high-strength portion 211A and the second high-strength portion 211B is less 490MPa (N / mm ²⁾ or more 1000MPa (N / mm ^2). The yield point or 0.2% yield strength of the normal strength portion 212 is 295 MPa (N / mm ² ) or more and 390 MPa (N / mm ² ) or less.
The main reinforcing bar 21 having the above-described configuration is made by partially quenching one normal reinforcing bar (SD345) having the same strength as that of the normal strength portion 212 into the high strength portion 211.

In the region including the G-shaped joint S2, the main reinforcement 21 has a first high-strength portion 211A at one end located outside the building, and a normal-strength portion 212 adjacent to the beam center side of the first high-strength portion 211A. The second high-strength portion 211B is located on the opposite side of the first high-strength portion 211A across the normal strength portion 212.
The first high-strength portion 211A is disposed in the G-shaped joint S2 and the second region 210A along the beam length direction from the G-shaped joint S2.

In the first embodiment, a method for designing a reinforced concrete structure will be described.
In FIG. 2, the design bending moment distribution is shown in (A), the schematic front view of the main bar is shown in (B), and the schematic cross-sectional view is shown in (C).
As shown in FIG. 2 (B), the main muscle 21 is composed of an upper part 21A and a lower part 21B arranged horizontally in the vertical direction, and a side part 21C arranged at a height position between the upper part 21A and the lower part 21B. .
In the first embodiment, the yield hinge position Q is used to calculate the bending moment as the design bending moment, and the boundary between the joint-side region 21M and the normal strength portion 212 in the first high-strength portion 211A. Set the part.

The dimension of the normal strength region 210B in the beam length direction, that is, the boundary position between the joint side region 21M and the normal strength portion 212 in the first high strength portion 211A, and the beam center side region 21N of the second high strength portion 211B. The dimension in the beam length direction at the boundary position between the normal strength portion 212 and the normal strength portion 212 is not less than 100 mm and not more than the length of the effective beam length d of the beam. Here, the effective beam d of the beam is the distance from the compression edge to the center of gravity of the tensile reinforcement, and when the lower reinforcement becomes tensile stress when a bending moment is applied, the center G of the lower main reinforcement G To the upper surface of the beam.
For example, in the arrangement of the main reinforcing bars 21 for the beam according to the present embodiment, when the height dimension of the beam is 400 mm, the effective length d of the beam can be 346 mm.
A plurality of shear reinforcement bars 22 are arranged at positions away from the cruciform joint S1 in the main bars 21 so as to cover the outer peripheral parts of the upper part 21A, the lower part 21B and the side parts 21C. These shear reinforcement bars 22 are arranged at equal intervals along the longitudinal direction of the beam.
The shear reinforcement 22 has a yield point or 0.2% yield strength (1275 MPa (N / mm ² )) greater than the yield point or 0.2% yield strength (345 MPa (N / mm ² )) of ordinary reinforcing bars. It is preferable to use (trade name of high-frequency thermal smelting Co., Ltd.). In this embodiment, instead of the Urbon 1275, the same yield point as that of the normal reinforcing bar or a shear reinforcing bar having a 0.2% proof stress may be used.

The design bending moment distribution shown in FIG. 2A becomes 0 at the connection portion of the normal strength portions 212 of the adjacent main bars 21, and the beam 2 of the beam-column joint portion 200 arranged on the left side of FIG. As you go to the root R of Note that the design bending moment shown in FIG. 2A is obtained by adding an external force moment to the moment of the constant load (self-weight). The design bending moment is obtained by a normal design method.
Calculation of the amount of reinforcing bars in the main reinforcement 21 is based on the reinforced concrete structure calculation criteria and the same explanation (The Architectural Institute of Japan, February 20, 2010, 8th edition, 1st edition), pages 14 to 16.
When the tensile reinforcement ratio of the beam is equal to or less than the balanced reinforcement ratio, the allowable bending moment (design bending moment) is given by the following equation.
M = a _t f _t j ...... Formula (A)

Here, a _t is the tensile reinforcing bar cross-sectional area, f _t is the allowable tensile stress of the rebar, j is the stress center distance of the beam. Tensile reinforcement cross section a _t, if main reinforcement 21 is disposed are provided in plurality are divided up and down, is the sum of the cross-sectional area of the main reinforcement 21 arranged vertically, respectively.
j may be (7/8) d or 0.9d. The allowable tensile stress degree f _t can be obtained from the following table defined in the reinforced concrete structure calculation criteria and explanation. For example, in the main muscle 21 of SD345, the short-term allowable tensile stress is 345 N / mm ² .

In addition to the calculation of the above formula (A), the beam is required to comply with the following conditions.
The tensile rebar cross-sectional area of the portion that receives positive and negative maximum bending moments during long-term loading is 0.004 bd (b is the beam width) or 4/3 times the amount required by the existing stress, which is the smaller value.
The main beam is a double beam over the entire span.
The main reinforcing bars are deformed reinforcing bars of D13 (D is the nominal name) or higher.
The opening of the main bar is at least 25 mm and at least 1.5 times the diameter of the deformed bar (nominal numerical value mm).
The arrangement of the main bars shall be two or less, except in special cases.

M is a moment value obtained from the design bending moment graph shown in FIG. The moment value M is a value at the position Q of the yield hinge.
In addition, the stress of the root R of the column beam joint part 200 of the main reinforcement 21 is below the yield point of the first high-strength portion 211A and the second high-strength portion 211B.
In the design bending moment shown in FIG. 2 (A), the maximum value is the position of the base R on the left side of the beam, the minimum value is the base of the right side of the beam, and these intermediate positions (normality of adjacent main bars 21) It is 0 in the vicinity of the position where the strength portions are joined (near the center of the beam). The position Q of the yield hinge is smaller than the base R.

As shown in FIG. 2B, the dimension between the vertical surfaces facing each other between adjacent columns 3 and the dimension S from the base R to the position Q of the yield hinge are appropriately set by the designer based on the bending moment distribution. Has been. The value at the base R of the design bending moment and the dimension from the base R at the position where the moment value is 0 are known numerical values at the time of examining the position of the yield hinge by prior analysis or the like. Therefore, as the moment value M at the position Q of the yield hinge, a numerical value obtained based on the ratio of these numerical values may be used.
In the present embodiment, the amount of reinforcing bars of the main reinforcing bar 21 is calculated from the value at the position Q of the yield hinge of the design bending moment shown in FIG.
Rebar amount is determined from the tensile reinforcing bar cross section a _t. Rebar number is obtained by dividing the cross-sectional area of the main reinforcement 21 per one from the cross-sectional area a _t.

Based on such calculation, the cross-sectional area of the main bar 21 is obtained, and further, the diameter and the number of the main bars 21 are obtained from the cross-sectional area. For example, a 906Mm ² rebar of the upper from the center of the beam, a reinforcement amount 906Mm ² lower, if the reinforcement of the upper and lower are respectively 906Mm ² required, as main reinforcement 21 of the upper 21A, the center Two main muscles 21 of D13 (SD345) are arranged, one main muscle 21 of D16 (SD345) is arranged at each corner, and two main muscles 21 of D13 are arranged in the center as the main muscle 21 of the lower part 21B. The main muscles 21 of D13 are arranged one by one at both corners, and the main muscles 21 of the side parts 21C are arranged one by one on the top, bottom, left and right (see FIG. 2C).

Therefore, in the first embodiment, the following effects can be achieved.
(1) The first high-strength portion 211A of the beam main bar 21 is a joint-side region 21M located at the cross-shaped joint S1, and the second high-strength portion 211B is sandwiched between the normal strength portions 212 and the cross-shaped joint S1. When the beam center side region 21N located on the opposite side of the beam is calculated, and the amount of reinforcing bars of the main bar 21 is calculated as the bending moment at the position Q of the yield hinge as the design bending moment, the position Q of the yield hinge is determined as the joint side region 21M. And the normal strength portion 212. Therefore, when a large load such as an earthquake occurs in a reinforced concrete structure, the force concentrates on the boundary between the first high-strength portion 211A and the normal strength portion 212, and fractures such as cracks will diffuse toward the beam center side. However, since the high-strength region includes not only the first high-strength portion 211A disposed in the joint-side region 21M but also the second high-strength portion 211B disposed in the beam center-side region 21N, the diffusion of destruction It is suppressed.

Moreover, the position Q where the yield hinge is set can be controlled from the root R of the cross-shaped joint S1 to a predetermined position in the beam length direction.
FIG. 3A is a schematic diagram of the beam according to the first embodiment, and FIG. 3B is a graph showing the relationship between the attachment length Ld of the main reinforcement for the beam and the stress distribution. In the above description, the boundary position between the joint-side region 21M and the normal strength portion 212 in the first high-strength portion 211A, and the boundary position between the beam center-side region 21N and the normal strength portion 212 in the second high-strength portion 211B. Although the preferable dimension in the beam length direction is 100 mm or more and not more than the length of the effective beam d of the beam, here, in order to simplify the description, the joint-side region 21M and the normal strength portion 212 are separated. The boundary position was the base of the beam.
3A and 3B, in the main reinforcing bar 21 for the beam according to the first embodiment, the actual stress distribution σ1 occurs at the position Q of the yield hinge. Cracks C occur in the vicinity of the yield hinge position Q, and the actual stress distribution σ1 continues to be a high value from the yield hinge position Q over the length x of the normal strength portion 212. In the region corresponding to the strength portion 211B, the value becomes low, and the crack generation range is reduced as compared with the conventional example. A stress distribution σ2 considered in the design is set corresponding to the actual stress distribution σ1.
From the above, when the length of the main bar 21 for the beam is long, the joint side region 21M is positioned far from the root R of the column beam joint 200, and when the length of the main bar 21 is short, the joint The part-side region 21M is positioned close to the root R of the beam-column joint 200. Thus, in 1st Embodiment, the freedom degree on the design of a reinforced concrete structure becomes large.

On the other hand, in the main bars for beams of the conventional example, all of which have the same strength, as shown in FIGS. 4 (A) and 4 (B), the length from the root R of the column beam joint 200 to the length of the effective beam d The stress distribution σ1 is high, and the degree of freedom in designing a reinforced concrete structure is limited.
FIG. 4A is a schematic diagram of a conventional beam, and FIG. 4B is a graph showing the relationship between the attachment length of the main bars for the beam and the stress distribution.
4A and 4B, the actual stress distribution σ1 is maximum at the position Q of the yield hinge in the conventional beam main reinforcement, but is the maximum value unlike the first embodiment. Is the root R of the beam-column joint 200. The actual stress distribution σ1 has a continuous high value over the dimension corresponding to the length of the effective beam length d from the root R of the beam-column joint portion 200. Become. Therefore, in the conventional example, when setting the stress distribution σ2 considered in the design corresponding to the actual stress distribution σ1, the design stress distribution σ2 must be a high value over at least the effective beam length d. Don't be. From the above, unlike the first embodiment, in the conventional example, the degree of freedom in designing a reinforced concrete structure is limited.

(2) Of the normal strength portion 212, the dimension in the beam length direction between the boundary position with the joint side region 21M and the boundary position with the beam center side region 21N is 100 mm or more and less than the length of the effective beam length d of the beam. Therefore, when a large earthquake or the like occurs, it is possible to suppress the breakage of the beam from progressing to the column beam joint and to reliably break the beam main bar 21.

(3) Since the through-hole H for equipment piping is provided in the high-strength region, piping work can be performed using the through-hole H for equipment piping. In addition, the area where the facility piping through-hole H is provided is a high-strength region, and the diffusion of cracks is suppressed. Therefore, even if the facility piping hole is constructed, the strength reduction of the building can be reduced.

(4) Since the first through hole H1 and the second through hole H2 are disposed across the normal strength portion 212 where the yield hinge is set, the piping work can be performed more easily.

(5) The main reinforcing bars 21 are arranged at the cross-shaped joint S1 because one normal reinforcing bar having the same strength as that of the normal strength portion 212 is partially quenched to form the first high strength portion 211A and the second high strength portion 211B. It is not necessary to increase the thickness of the high-strength part. Therefore, handling on site becomes easy.

(6) Since the joint-side region 21M is composed of the cruciform joint S1 and the second region 210A located in the beam length direction from the root R of the cruciform joint S1, the position Q of the yield hinge is that of the beam 2 The position is away from the root R. Therefore, the design wall moment is reduced, and the amount of reinforcing bars is reduced accordingly, so that it is not necessary to increase the cross-sectional area of the end and the column beam joint portion 200, and as a result, the living space can be widened. .

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the configuration of the main muscle 21 is different from that of the first embodiment, and other configurations are the same as those of the first embodiment. In the description of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 5B, in the region including the cruciform joint S1, the main muscle 21 has a first high-strength portion 211A at the center thereof, and a first normal strength portion next to the first high-strength portion 211A. 212A, there is a second high strength portion 211B on the opposite side of the first high strength portion 211A across the first normal strength portion 212A, and there is a second normal strength portion 212B next to the second high strength portion 211B.

The first normal strength portion 212A is disposed in a normal strength region 210B located on the opposite side of the cruciform joint S1 across the second region 210A.
The second normal strength portion 212B is disposed at the end of the main bar 21, and the adjacent main bars 21 are connected to each other by the joint 4 at the second normal strength portion 212B.
In the second embodiment, the position at which the second ordinary strength portion 212B is arranged is a portion where the central design bending moment M is small as shown in FIG.

In the second embodiment, the method for designing a reinforced concrete structure is the same as that in the first embodiment.
In the second embodiment, in addition to the same effects as (1) to (6) of the first embodiment, the following effects can be achieved.
(7) Since the portion where the bending moment at the center of the main reinforcement 21 for the beam is small is set as the normal strength, the center side of the beam is set as the second normal strength portion 212B in addition to the position Q where the yield hinge is set. Manufacturing costs can be reduced.

[Third Embodiment]
A third embodiment of the present invention will be described with reference to FIG.
The third embodiment differs from the first embodiment in the configuration of the main muscle 21, and the other configurations are the same as those in the first embodiment. In the description of the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 6B, the main reinforcing bar 21P is composed of ordinary reinforcing bars whose yield point or 0.2% yield strength is defined by JISG3112. The yield point or 0.2% yielding strength of ordinary reinforcing bars is The pressure is from 295 MPa (N / mm ² ) to 390 MPa (N / mm ² ).

The length of the main bar 21P is the same as that of the main bar 21 of the first embodiment, and the arrangement position of the main bar 21P is the same as that of the main bar 21: four in the upper part 21A, four in the lower part 21B, Each book.
In this embodiment, the normal strength portion 212 is composed of the main muscle 21P described above, and the first high strength portion 211A and the second high strength portion 211B are each composed of the main muscle 21P and the four reinforcing bars 21Q. Yes.
The reinforcing bars 21Q are arranged in the cruciform joint S1 and the second region 210A along the beam length direction from the cruciform joint S1.
The reinforcing bar 21Q is composed of a normal reinforcing bar made of the same material as the main bar 21P. For example, the reinforcing bars 21Q are arranged between the side portions 21C (see FIG. 6C), and the number thereof is set based on the design bending moment, as will be described later.

The design bending moment distribution shown in FIG. 6 (A) is the same as the design bending moment distribution shown in FIG. 2 (A).
The moment value M is a value at the position Q of the yield hinge. In this embodiment, the position Q of the yield hinge is a boundary portion between the first high-strength portion 211A and the normal strength portion 212.
In the present embodiment, the amount of reinforcing bars of the main reinforcement 21P is calculated by the same method as in the first embodiment. In the section of the dimension S, the amount of reinforcing bars may be set such that the stress obtained by back calculation with respect to the bending moment of the root R of the beam-column joint 200 is equal to or less than the yield point of the reinforcing bars. As a result, by arranging two reinforcing bars 21Q between the main bars 21P constituting the side portions 21C adjacent to the left and right (see FIG. 6C), the first high strength higher than that of the normal strength portion 212 is obtained. The strength portion 211A and the second high strength portion 211B could be set.

Therefore, in 3rd Embodiment, there can exist the following effect besides having the same effect as (1)-(4) (6) of 1st Embodiment.
(8) Since the position Q of the yield hinge is set as the boundary of the reinforcement when calculating the amount of reinforcing bar of the main bar 21P for the beam as the bending moment for the design at the position Q of the yield hinge, the design bending moment The moment value of becomes smaller, and the amount of reinforcing bars can be reduced accordingly.

(9) Since the high-strength region is formed by increasing the number of rebars from the normal strength region, a part of one normal rebar is quenched to form the first high-strength portion 211A and the second high-strength portion 211B. Compared to the case, the manufacturing cost of the reinforcing bars can be reduced.

[Fourth Embodiment]
A fourth embodiment of the present invention will be described with reference to FIGS.
The fourth embodiment is different from the first embodiment in the joining structure of the normal strength portion 212 and the first high strength portion 211A of the main muscle 21 and the joining structure of the normal strength portion 212 and the second high strength portion 211B. The configuration is the same as in the first embodiment. In the description of the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the fourth embodiment, the first high-strength portion 211A, the normal strength portion 212, the joint portion 210, and the second high-strength portion 211B and the joint portion 210 of the normal strength portion 212 are joined like “nodes”. (See FIG. 7C).

FIG. 7 shows a case where the first high-strength portion 211A and the normal-strength portion 212 each composed of one main bar are joined by friction welding. The first high-strength portion 211A and the normal strength portion 212 are made of the same material, and the first high-strength portion 211A is thicker than the normal strength portion 212, so that the strength is high.
In FIG. 7A, the end surfaces of the first high-strength portion 211A and the normal-strength portion 212 are brought into contact with each other.
Thereafter, as shown in FIG. 7B, one of the first high-strength portion 211A and the normal strength portion 212, for example, the first high-strength portion 211A is pressed toward the normal strength portion 212, and the other, for example, The normal strength portion 212 is rotated in its axial direction. Since the first high-strength portion 211A and the normal strength portion 212 are relatively rotated while being contact-pressed, friction heat is generated at the abutting portion between the first high-strength portion 211A and the normal strength portion 212. Then, as shown in FIG. 7C, the press-contacted end surfaces of the first high-strength portion 211A and the normal-strength portion 212 are joined in a swelled state like a “node”.

FIG. 8 shows an example in which the joining portion 210 is formed by gas pressure welding.
In FIG. 8A, the end surfaces of the first high-strength portion 211A and the normal strength portion 212 are brought into contact with each other. Thereafter, as shown in FIG. 8B, the first high-strength portion 211A and the normal strength portion 212 are pressed together in a direction close to each other, and the butted portion is heated along the outer periphery with an oxygen acetylene flame or the like. . Then, as shown in FIG. 8C, the press-contacted end surfaces of the first high-strength portion 211A and the normal strength portion 212 are joined in a swelled state like a “node”.

FIG. 9 shows an example in which the joint portion 210 is formed by butt welding.
In FIG. 9A, the end surfaces of the first high-strength portion 211A and the normal strength portion 212 are in a state of abutting each other. Thereafter, as shown in FIG. 9B, each of the first high-strength portion 211A and the normal strength portion 212 is gripped by the electrodes T, and the butted portions are pressed by moving these electrodes T in directions close to each other. In addition, the butt portion is heated by energizing between the two electrodes T. Then, as shown in FIG. 9C, the press-contacted end surfaces of the first high-strength portion 211A and the normal-strength portion 212 are joined in a swelled state like a “node”. The welding in the present embodiment is not limited to the butt welding as described above, and the joint portion 210 can be formed by other welding.

In the fourth embodiment, the method for designing a reinforced concrete structure is the same as that in the first embodiment.
In the fourth embodiment, in addition to the same effects as (1) to (6) of the first embodiment, the following effects can be achieved.
(10) Since the joining portion 210 is formed by any one of friction welding, gas welding, and butt welding, the portion where the first high-strength portion 211A and the ordinary strength portion 212 are abutted is a “node”. It becomes inflated. The close force between the swollen portion and the concrete portion is increased.

[Fifth Embodiment]
A fifth embodiment of the present invention will be described with reference to FIGS.
The fifth embodiment is different from the fourth embodiment in the configuration of the joint, and the other configurations are the same as those in the fourth embodiment. In the description of the fifth embodiment, the same components as those in the first embodiment and the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 10 shows the main part of the reinforcing bar structure of the fifth embodiment.
In FIG. 10, the large-diameter first high-strength portion 211 </ b> A and the small-diameter normal-strength portion 212 are connected to each other via a joint portion 24. The first high-strength portion 211A and the small-diameter ordinary strength portion 212 are different reinforcing bars.
The ends of the first high-strength portion 211A and the normal strength portion 212 are joined at the center position of the joint portion 24, and the distance from the center position to the pillar 3 is the second region 210A as a high-strength region. The This center position is the position Q of the yield hinge.

A specific configuration of the joint 24 is shown in FIGS. 11 and 12.
In FIG.11 and FIG.12, the junction part 24 has the external thread part 211T formed in the edge part of the 1st high intensity | strength part 211A, the external thread part 212T formed in the edge part of the small diameter normal intensity | strength part 212, and these. And a coupler 25 screwed into the male screw portions 211T and 212T. The end surface 211D of the first high-strength portion 211A and the end surface 212D of the normal strength portion 212 are in contact with each other.
The coupler 25 is a nut-shaped member whose outer peripheral surface is hexagonal. The female screw portion of the coupler 25 includes a large-diameter portion 252T that matches the diameter of the male screw portion 211T of the first high-strength portion 211A, and a small-diameter portion 251T that matches the diameter of the male screw portion 212T of the normal strength portion 212. A step is formed between the large diameter portion 252T and the small diameter portion 251T.

In the fifth embodiment, the method for designing a reinforced concrete structure is the same as that in the first embodiment.
In the fifth embodiment, the following effects can be achieved in addition to the same effects as (1) to (6) of the first embodiment.
(11) Since the joint portion 24 includes the coupler 25 screwed into the male screw portion 211T of the first high-strength portion 211A and the male screw portion 212T of the normal strength portion 212, the joint portion is joined by friction welding, gas pressure welding, or welding. Compared with the case of forming 210, rebar connection work at the construction site is facilitated.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
FIG. 13 shows the joint portion of the sixth embodiment.
In the sixth embodiment, the configuration of the joint portion 26 is different from that of the fifth embodiment, and other configurations are the same as those of the fifth embodiment. In the description of the sixth embodiment, the same components as those of the fifth embodiment are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 13, the first high-strength portion 211 </ b> A made of a large-diameter rebar and the normal-strength portion 212 made of a small-diameter rebar are connected to each other through a joint portion 26.
The joint portion 26 includes a female screw portion 211C formed at the end portion of the first high-strength portion 211A and a male screw portion 212T formed at the end portion of the normal strength portion 212.

In the sixth embodiment, the same effects as in the third embodiment can be obtained, and the following effects can be obtained.
(12) The joint portion 26 includes a male screw portion 212T formed in the normal strength portion 212, and a female screw portion 211C screwed into the male screw portion 212T and formed at the end of the large-diameter first high-strength portion 211A. Therefore, a coupler is unnecessary as compared with the fifth embodiment. Therefore, not only the on-site work is facilitated, but there is no need to separately prepare a coupler, so that management when constructing the reinforcing bar structure is facilitated.

It should be noted that 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.
For example, the present invention can be applied to civil engineering structures such as bridges in addition to building structures.
Furthermore, in the present invention, the length dimension of the second region 210A may be 0, that is, the first high-strength portion 211A may be arranged only in the cruciform joint S1.
Moreover, it is not always necessary to provide the through hole H for equipment piping. Even if it is provided temporarily, one of the first through hole H1 and the second through hole H2 may be provided.

  INDUSTRIAL APPLICABILITY The present invention can be used for a reinforced concrete building structure or a civil engineering structure.

  DESCRIPTION OF SYMBOLS 1 ... Reinforcement structure, 100 ... Concrete body, 2 ... Beam, 200 ... Column beam joint part, 21 ... Main reinforcement, 210A ... Second area (high strength area), 210B ... Normal strength area, 210S ... First area, 211A ... First high strength portion, 211B ... second high strength portion, 212 ... normal strength portion, 212A ... first normal strength portion, 212B ... second normal strength portion, 21M ... joint side region, 21N ... beam central side region, 21P ... Main reinforcement, 21Q ... Reinforcement, 22, 32 ... Shear reinforcement, 24 ... Joint, 25 ... Coupler, 3 ... Pillar, 31 ... Reinforcement material, 4 ... Joint, H ... Through hole for equipment piping, H1 ... One through hole, H2 ... second through hole, Q ... position of yield hinge, R ... root

Claims (11)

A plurality of main bars for the beam joined to the column, the main bars for the beam having a normal strength portion and a high strength portion having a strength higher than that of the normal strength portion and arranged adjacent to the normal strength portion; A method of designing a reinforced concrete structure having
The high-strength portion is located on a side opposite to the column-beam joint with the normal-strength portion sandwiched between at least a beam-beam joint portion to be joined to the column among the main bars for the beam. Placed in the center area of the beam
In calculating the amount of reinforcing bar of the main reinforcing bar for the beam, the bending moment at the position of the yield hinge as the bending moment for design, the position of the yield hinge is the joint strength region and the normal strength portion of the high strength portion. A design method for reinforced concrete, characterized by being set at the boundary of In the design method of the reinforced concrete structure described in Claim 1,
The dimension in the beam length direction between the boundary position between the joint-side region and the boundary position between the beam center side region in the normal strength portion is 100 mm or more and less than the length of the effective beam length of the beam. Design method for reinforced concrete structures. In the design method of the reinforced concrete structure described in Claim 1 or Claim 2,
A method for designing a reinforced concrete structure in which a portion having a small bending moment at the center of the main reinforcing bars for beams is set to a normal strength. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 3,
The high-strength portion is provided with a through-hole for equipment piping. In the design method of the reinforced concrete structure described in Claim 4,
The joint-side region includes a first region disposed in the beam-column joint, and a second region that is formed continuously with the first region and extends in the beam length direction from the beam-column joint. ,
The facility piping through-hole has a first through-hole disposed in the second region and a second through-hole disposed in the beam center side region. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 5,
The normal strength portion has a yield point or 0.2% yield strength defined in JIS G3112, and the high strength portion has a yield point or 0.2% yield strength greater than the normal strength portion,
The method for designing a reinforced concrete structure, wherein the main reinforcing bar for the beam is made by partially quenching one normal reinforcing bar having the same strength as the normal strength portion to form the high strength portion. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 6,
The method for designing a reinforced concrete structure, wherein the thickness of the high-strength portion is larger than the thickness of the normal-strength portion. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 7,
The normal strength portion and the high strength portion are connected to each other through the joint between the ends facing each other,
The joining portion is formed by any one of friction welding, gas welding, and welding. In the design method of the reinforced concrete structure described in Claim 7,
The normal strength portion and the high strength portion are connected to each other through the joint between the ends facing each other,
The joint portion includes a coupler that is screwed into a male screw portion formed in the normal reinforcing bar portion and a male screw portion formed in the high-strength portion, respectively. In the design method of the reinforced concrete structure of Claim 7,
The normal strength portion and the high strength portion are connected to each other through the joint between the ends facing each other,
The joint portion includes a male screw portion formed in the normal reinforcing bar portion and a female screw portion screwed into the male screw portion and formed in the high-strength portion.   A reinforced concrete structure designed by the method for designing a reinforced concrete structure according to any one of claims 1 to 10.

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