JP6568388B2 - 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.

When designing buildings, bend and yield at the column bases on the first floor and beam ends on the second and higher floors in order to prevent the collapse of the buildings and the collapse of the layers in response to extremely rare earthquakes. In other words, a design method that allows the generation of a yield hinge is adopted.
In the conventional design method of the column base on the first floor, the bending moment is maximized at the base, so the number of main bars of the column base on the first floor is calculated based on the magnitude of the bending moment at the base. The

That is, conventionally, in order to design a reinforced concrete structure, the cross-section calculation for the column bending is performed based on the design bending moment. The cross-sectional calculation is obtained as a reinforcing bar cross-sectional area from the bending moment and other relationships (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 columns. The sum of the cross-sectional areas of the main bars for a plurality of columns is converted as the number of reinforcing bars for the number of main bars for the columns.
In a typical reinforced concrete structure, the design bending moment is maximized at the base of the column base or the top of the column, so the diameter and number of main bars for the column are based on the magnitude of the design bending moment at the base. Is calculated.

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

As shown in Non-Patent Document 1, the reinforcing bar cross-sectional area is calculated based on the design bending moment, and is generally set so that the base of the column becomes a yield hinge. Based on the magnitude of the design bending moment at the base, the size and number of the main bars for the column are calculated.
Therefore, as for the size and number of the main bars for the column, if the bending moment at the base is large, if the strength of the main bars for each column is the same, many main bars for the column may be required. Or a major bar with a large diameter is required.
However, if the number of main bars for the column cannot be increased, either the column width can be increased or the column can be increased to reduce the amount of the main bar, and the column or the column base such as the column base or head The cross-sectional area of the beam joint must be increased. If the cross-sectional area of the beam-column joint is increased, the cross-sectional area of the column and the entire beam also increases, and the living space is reduced.

  An object of the present invention is to provide a method for designing a reinforced concrete structure and a reinforced concrete structure capable of widening a living space.

The method for designing a reinforced concrete structure of the present invention includes a plurality of column main bars to be joined to a beam, and the column main bars include a normal strength portion and a high strength portion having a strength higher than that of the normal strength portion. The high-strength portion includes at least one of a column leg portion and a column head portion that are joined to the beam among the main reinforcing bars for the column, and a column length direction from the column beam joint portion; The normal strength portion is a method of designing a reinforced concrete structure located on the opposite side of the column beam joint with the high strength region interposed therebetween, and a column for planning a yield hinge. Is set at a boundary between the high-strength portion and the normal-strength portion at a position away from the base of the column-beam joint, and the column-beam joint and the high-strength are sandwiched between the normal-strength portions. The high strength is applied to the central region of the column opposite to the strength region. Characterized in that a portion.

In the present invention having the above-described configuration, the high-strength portion is disposed in the high-strength region including the column beam joint, and the normal-strength portion is disposed in the normal-strength region adjacent to the high-strength region. Therefore, when a large force is generated in the reinforced concrete structure, the deformation concentrates on the boundary portion between the high-strength portion and the normal strength portion, not on the base portion at the end of the beam-column joint. Therefore, in the present invention, the position of the yield hinge is set at the boundary between the normal strength portion and the high strength portion.
By setting the position of the yield hinge not at the base of the beam-column joint of the column but at the boundary away from the base, the design bending moment becomes smaller than that at the base, so the amount of reinforcing bars can be reduced.
Therefore, in the present invention, since the amount of reinforcing bars is small, it is not necessary to increase the cross-sectional area of the beam or the column beam joint, and therefore the living space can be widened.
And it is the structure which has arrange | positioned the high intensity | strength part in the column center side area | region on the opposite side to the said column beam junction part and the said high intensity | strength area | region on both sides of the said normal intensity | strength part.
In this configuration, when a large load such as an earthquake occurs in a reinforced concrete structure, the fracture concentrates at the boundary between the high-strength part and the normal-strength part, and the fracture such as cracks tends to spread toward the center of the column. However, since the high-strength portion is disposed not only in the joint portion side region but also in the column center side region, diffusion of destruction toward the column center side is suppressed.

In the reinforced concrete design method, it is preferable that the number of the main bars for the column is calculated by the strength of the normal strength portion based on the design bending moment at the position of the yield hinge.
In this configuration, the number of reinforcing bars of the main bars for the column is obtained as the number. The design bending moment is the largest at the base of the beam-to-column joint, and the magnitude decreases as the distance from the beam-to-column joint increases, so the yield hinge is not the base but the boundary from the base. By doing so, the moment value of the design bending moment is reduced, and the number of main bars for the column is reduced accordingly.
Therefore, since the number of column main bars is calculated from the design bending moment, the amount of reinforcing bars of the column main bars can be easily calculated.

In the design method of a reinforced concrete structure, it is preferable that a stress of a reinforcing bar at a base portion of the column beam joint is equal to or lower than a standard yield point of the high strength portion.
In this configuration, since the stress at the base portion of the beam-column joint portion of the main bar is equal to or less than the standard yield point of the high-strength portion, the root portion of the beam-column joint portion does not yield before the set yield hinge position. Therefore, the standard of reinforced concrete construction itself can be satisfied.

In the reinforced concrete design method, a configuration in which the high-strength portion and the normal-strength portion are connected to each other by a joint is preferable.
In this configuration, the high-strength portion and the normal-strength portion are integrated with each other through the joint, so that a large strength can be obtained even if one column main bar is short.

In the reinforced concrete design method, the normal strength portion has a yield point or 0.2% yield strength defined by JISG3112, 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 column is hardened at least a part of one normal reinforcing bar having the same strength as that of the normal strength portion to form the high strength portion.
In this configuration, since a high strength portion is formed by quenching a single reinforcing bar whose yield point or 0.2% proof stress is defined in JIS G3112, the thickness of the high strength portion arranged at the column beam joint is increased. It doesn't need to be thick. 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 reinforced concrete structure, the structure which formed in part the high intensity | strength part arrange | positioned in the said column center side area | region is preferable.
In this configuration, since the column central region is partially made a high strength portion, the manufacturing cost can be reduced as compared with the case where all the reinforcing bars are made a high strength portion.

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

Schematic of the reinforced concrete structure concerning 1st Embodiment of this invention. The schematic front view which shows the reinforcing bar structure of the 1st floor part. (A) is a schematic cross-sectional view of a column, (B) is a moment distribution diagram showing the relationship between the position of the column main bar and the design bending moment, and (C) is a schematic front view of the main bar. The reinforced concrete structure concerning 2nd Embodiment of this invention is shown, (A) is a moment distribution diagram which shows the relationship between the position of the main reinforcement for pillars, and the bending moment for design, (B) is a schematic front view of the main reinforcement. The schematic front view which shows the reinforcing bar structure of the 1st floor part of the reinforced concrete structure concerning 3rd Embodiment of this invention. (A) is a schematic cross-sectional view of a column, (B) is a moment distribution diagram showing the relationship between the position of the column main bar and the design bending moment, and (C) is a schematic front view of the main bar. Schematic of the reinforced concrete structure concerning the modification of this invention. Schematic of the reinforced concrete structure concerning the different modification of this invention. Schematic of the reinforced concrete structure concerning the further different modification of this invention. The figure which shows the further different modification of this invention, and is equivalent to FIG. The figure which shows the further different modification of this invention, and is equivalent to FIG.

Embodiments of the present invention will be described with reference to the drawings. Here, in description of each embodiment, the same component is attached | subjected with the same code | symbol and description is abbreviate | omitted.
[First Embodiment]
1st Embodiment of this invention is described based on FIGS. 1-3 of drawing.
FIG. 1 shows a schematic configuration of a reinforced concrete structure according to the first embodiment.
In FIG. 1, the case where a load such as the largest class earthquake that occurs extremely rarely is applied to the building is indicated by a solid line, and the case where no load is applied is indicated by an imaginary line.
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. The building of this embodiment has a flat roof.

The beam 2, the column 3, and the foundation 10 </ b> C are joined by a column beam joint 10. The column beam joints 10 are located above and below each floor. The column beam joints 10 at the bottom of the first floor are column bases 10A, and the column beam joints 10 on the top floor are column heads 10B. is there. The column base 10A on the first floor of the building is joined to the foundation 10C.
In the first embodiment, when a large load is applied to the building, the joint portion between the beam 2 and the column beam joint 10 becomes the yield hinge H, and the joint between the column 3 and the column base 10A of the first floor portion of the building. Is the yield hinge Q. These yield hinges H and Q prevent the building itself from collapsing.

FIG. 2 shows a schematic configuration of the reinforcing bar structure of the first floor portion.
As shown in FIG. 2, the beam 2 surrounds the reinforcing bars 21 in a plane intersecting the axial direction of the reinforcing bars 21, and the reinforcing bars 21 for a plurality of beams extending in the horizontal direction and equally spaced. And a plurality of beam reinforcing bars 22 for reinforcing the shear strength of the beam 2.
The foundation 10 </ b> C extends in the horizontal direction and has a plurality of reinforcing bars 21 for the beams, and the reinforcing bars 21 are arranged at equal intervals so as to surround the reinforcing bars 21 in a plane intersecting the axial direction of the reinforcing bars 21. And a plurality of beam reinforcing bars 22 for reinforcing the shear strength.
In the present embodiment, the reinforcing bar material 21 and the shear reinforcing bar 22 are ordinary reinforcing bars.

The column 3 extends in the vertical direction and has a plurality of column main bars 31 arranged at predetermined intervals, and surrounds the column main bars 31 in a plane that intersects the axial direction of the column main bars 31. And a plurality of column shear reinforcement bars 32 that are arranged in the extending direction of the column main bars 31 and reinforce the shear strength of the columns 3.
The column main reinforcement 31 includes a high-strength portion 311 whose lower end is connected to the base 10C in a region including the column base portion 10A, a normal-strength portion 312 connected to the high-strength portion 311, a normal-strength portion 312 and a high-strength portion. And a joint 4 connecting the portion 311.

The high-strength portion 311 is disposed in the column base 10A and the high-strength region 310A along the column length direction from the column base 10A.
The shear reinforcing bar 32 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). 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 yield hinge Q is set at the boundary between the high strength portion 311 and the normal strength portion 312 at a position away from the base portion R of the column base portion 10A.
The normal strength portion 312 is disposed in a normal strength region 310B located on the opposite side of the column base 10A across the high strength region 310A.
In the first embodiment, the high-strength portion 311 is composed of one high-strength reinforcing bar. The normal strength portion 312 is composed of a plurality of normal strength reinforcing bars. The normal strength portion 312 where the upper end and the lower end of the high strength portion 311 are connected has the upper end reaching the column beam joint 10 at the second floor portion.

The normal strength portion 312 has a yield point or 0.2% yield strength defined by JISG3112. The high strength portion 311 has a higher strength than the normal strength portion 312.
For example, the yield point or 0.2% proof stress of the high strength portions 311 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 312 is 295 MPa (N / mm ² ) or more and 390 MPa (N / mm ² ) or less.
The high-strength portion 311 is manufactured by quenching one ordinary reinforcing bar (SD345) having the same strength as the normal-strength portion 312.
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.

Next, a method for designing a reinforced concrete structure in the first embodiment will be described.
In FIG. 3, a schematic cross section of the column 3 is shown in (A), a design bending moment distribution is shown in (B), and a schematic front view of the main bars for the column is shown in (C).
As shown in FIG. 3A, the pillar 3 has a rectangular cross section having a vertical dimension b and a horizontal dimension D, and a plurality of main bars 31 are arranged along the outer side. Shear reinforcement bars 32 are arranged on the outer peripheral portions of these main bars 31.
The design bending moment distribution shown in FIG. 3 (B) corresponds to the column 3 shown in FIG. 3 (C). The value of the design bending moment is generally the largest at the base R of the column base 10A, the generated bending moment on the column base calculated by the frame analysis is Mu (plus), and the column base 10A The root portion R of the column beam joint 10 directly above is the smallest, the generated bending moment on the column head side becomes Ms (minus), and becomes 0 in the middle of the length direction of the column 3. Note that the design bending moment shown in FIG. 3B is obtained by adding an external force moment to the moment of a constant (self-weight) load. In FIG. 3B, it is assumed that the ultimate bending strength My is reached at the base portion R of the column base portion 10A and a yield hinge is formed. After reaching the ultimate bending strength My, even if the external force increases, the bending moment does not increase any more and becomes constant. Therefore, the generated bending moment Mu at the portion where the yield hinge is formed reaches a peak.
The design bending moment is obtained by a normal design method.

Calculation of the amount of reinforcing bars for the main reinforcement 31 for pillars is the 2007 edition of the structural technical standards for buildings (supervised by the Ministry of Land, Infrastructure, Transport and Tourism, Housing Bureau Building Guidance Division and others, August 10, 2007, first edition, first edition issued) Conforms to pages 626 to 627.
An example of calculating the ultimate bending strength based on the column design bending moment will be described.
[Common subject matter]
The cross-sectional shape of the pillar 3 is a square whose one side length D is 1000 mm and whose other side length b is 1000 mm. The cross-sectional area of the pillar 3 is 1000 mm (1 m) × 1000 mm (1 m) = 1 m ² .
The concrete strength is F _c = 36 N / mm ² .
The axial force is N = 3,600,000N.

(A) In the case of normal strength reinforcing bars (reinforcing bars used: SD390)
As the main reinforcing bar 31, the ultimate bending strength My when all normal reinforcing bars are used is obtained.
The bending ultimate strength My of this cross section is 0 ≦ N ≦ N _b .
My = 0.5 · a _g · σ _y · g ₁ · D
+ 0.5 · N · D {1− (N / (b · D · F _c ))} (1)
a _g is a pillar main reinforcement total cross-sectional area (= cross-sectional area per one number × main reinforcement of the main reinforcement).
Assuming a case where 14 main bars having a nominal name D32 (16 in the figure are shown, but seven main bars effective for bending resistance) are used.
a _g ≈14 × 794 = 11,116 mm ²

σ _y is the main bar yield strength, and in this embodiment, SD 390 reinforcing bars are used, so σ _y = 390 N / mm ² .
g ₁ is the ratio of the distance between the center of gravity of the tensile muscle and the center of gravity of the compression muscle to the total length, and is determined by the arrangement and number of main muscles. The distance between the center of gravity of the tensile muscle and the center of gravity of the compression muscle is g ₁ · D. In this embodiment, g ₁ · D is 686 mm ² and g ₁ is 0.686.
N _b = 0.22 · (1 + g ₁ ) · b · D · Fc = 13,353,120 (N)
Therefore, since the condition of 0 ≦ N ≦ _Nb is satisfied, the premise of Expression (1) is established.
Substituting the above numerical values into equation (1),
My = 0.5 × 11,116 × 390 × 0.686 × 1,000
+ 0.5 × 3,600,000 × 1,000 {1- (3,600,000 / (1,000 × 1,000 × 36))}
= 1,497 (kN · m) + 1,620 (kN · m) = 3,117 (kN · m)

On the other hand, the ultimate bending strength of the column at the base portion R of the column-beam joint 10 is 3,117 kN · m, similar to the column base 10A, because the arrangement of the column main bars 31 is not different from that of the column base 10A.
The generated bending moment Ms on the stigma side is obtained by a normal frame analysis, and is 1,390 kN · m in this embodiment. Since the value of the generated bending moment Ms on the stigma side is equal to or less than the bending ultimate strength of 3,117 kN · m, no yield hinge is generated on the stigma side, that is, the column beam joint 10 immediately above the column base 10A.

3 (B) and 3 (C), the vertical hinge C between the vertical beams 2 adjacent to each other at the top and bottom, and the main reinforcement partly from the base R of the column base portion 10A is made high strength to yield hinge Q. The dimension S up to the position where the formation of is assumed is appropriately set by the designer based on the bending moment distribution.
For example, when the vertical distance C between the adjacent beams 2 on the upper and lower sides is 3000 mm and the dimension S from the base R of the column base 10A to the position where the formation of the yield hinge Q is assumed is 500 mm, Based on the design moment diagram of FIG. 3 (B), the bending moment M _Q generated at the position of the yield hinge _Q is calculated by back calculation. In the present embodiment, generating the bending moment _{M Q} is 2,366kN · m.

(B) When the main bar 31 is replaced with a main bar 31 having a high strength portion 311 Bending when all main strength bars are used for the main bar so that the main bar only needs to be replaced with a main bar for a column having a high strength portion The number of reinforcing bars at the boundary between the high-strength portion 311 and the normal strength portion 312 that is the same as the moment distribution is calculated.
Assuming that the main reinforcing bar 31 has six reinforcing bars with the name D32 (three on one side), g ₁ · D is 800 mm ² and g ₁ is 0.800.
Here, from Equation (1), the ultimate bending strength My is
My = 2,366 kN · m = 0.5 · a _g · σ _y · g ₁ · D
+ 0.5 · N · D {1- (N / (b · D · F _c ))}
a _g is 4,782mm ^2.
Number of main bars 31 = 4,782 mm ² / (16 × 16 × π≈794 mm ² ) = 6.02
In other words, when the pillar main bar 31 having the high-strength portion 311 is replaced, the number of the main bars 31 is approximately six, which is equal to the generated bending moment at the position of the yield hinge Q.

That is, the yield hinge Q is formed when the bending moment at the position of the yield hinge Q reaches 2,363 kN · m. The formation position of the yield hinge Q when the SD390 reinforcing bar is used over the entire length is the base R of the column base part 10A, but the bending moment distribution does not change, so only the formation position of the yield hinge Q is different. This means that the behavior of the entire building is completely the same as when the SD390 rebar is used over its entire length. If the bending moment distribution is significantly different, it will affect the bending moment distribution of other columns and beams, but by setting the number of reinforcing bars so that the bending moment distribution does not change, other columns and beams can be designed. It can be replaced with a main bar for a pillar having a high-strength portion without any influence.
Here, the ultimate bending strength when the number of reinforcing bars is 6 is set to be exactly 2366 kN · m. However, in actual design, the bending moment distribution changes depending on the setting conditions such as the position where the yield hinge is supposed to be formed and the number of reinforcing bars to be set. Therefore, the generation position of the yield hinge Q and the number of reinforcing bars are reset. Therefore, it will be recalculated from the frame analysis. Since the direction of the earthquake is unknown, if three are arranged per side, the total number of reinforcing bars is eight.

(C) Confirmation at the base R of the column base 10A Before yielding at a position 500 mm from the base R of the column base 10A, it is necessary to confirm that the column base 10A does not yield. Here, when the strength of the high-strength portion 311 is 900 N / mm ² , the following values are obtained.
When the strength of the high-strength portion 311 is 900 N / mm ² , the following values are obtained.
My = 0.5 · a _g · σ _y · g ₁ · D
+ 0.5 · N · D {1- (N / (b · D · F _c ))}
= 0.5 x 6 x 794 x 900 x 0.800 x 1,000 + 0.5 x 3,600,000 x 1,000 x {1-3,600,000 / (1,000 x 1,000 x 36)} = 1,715 (kN · m) + 1,620 (kN · m) = 3,335 (kN ・ m)
That is, the ultimate bending strength My when the strength of the high-strength portion 311 is 900 N / mm ² is 3,335 kN · m, and this value is when yielding at a position 500 mm from the base R of the column base 10A. Since it is larger than the moment of the base portion R, it can be seen that the column base 10A does not yield first.

Therefore, in the first embodiment, the following effects can be achieved.
(1) The position of the column 3 where the yield hinge Q is planned is a position away from the base portion R of the column base 10A, which is the column beam joint 10, and the boundary between the high strength portion 311 and the normal strength portion 312. Set in the department. Therefore, when a large force is generated in the reinforced concrete structure, deformation concentrates on the boundary portion between the high strength portion 311 and the normal strength portion 312, not on the base portion R of the column base portion 10 </ b> A. Therefore, the amount of reinforcing bars can be reduced, and it is not necessary to increase the cross-sectional area of the beam or the column beam joint, and the living space can be widened.

(2) Since the number of column main bars 31 is calculated as the strength of the normal strength portion 312 based on the design bending moment at the position of the yield hinge Q, the amount of reinforcing bars of the column main bars 31 is easily calculated. be able to.

(3) Since the stress of the reinforcing bar at the base portion R of the column base portion 10A is equal to or less than the standard yield point of the high strength portion 311, the base portion R of the column base portion 10A does not yield before the set position of the yield hinge Q. Therefore, the standard of reinforced concrete itself can be satisfied.

(4) Since the high-strength portion 311 and the normal-strength portion 312 are connected to each other by the joint 4, the high-strength portion 311 and the normal-strength portion 312 are integrated with each other through the joint 4. Even if the main muscle 31 is short, a large strength can be obtained.

(5) Since the high strength portion 311 is formed by quenching one ordinary reinforcing bar whose yield point or 0.2% proof stress is defined by JIS G3112, the high strength portion 311 disposed on the column base portion 10A There is no need to increase the thickness. From this point, it is not necessary to increase the cross-sectional area of the column base 10A.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG.
The second embodiment is different from the first embodiment in the configuration of the pillar main reinforcement 51, and the other configurations are the same as those in the first embodiment.
As shown in FIG. 4B, the column 5 includes a plurality of column main reinforcing bars 51 and a plurality of column reinforcing bars arranged in the extending direction of the main bars 51 to reinforce the shear strength of the columns 5. 32.
The column main reinforcement 51 includes a partial strength reinforcing bar 51A whose lower end is connected to the foundation 10C in a region including the column base 10A, and a normal strength reinforcing bar 51B connected to the partial strength reinforcing bar 51A via a joint (not shown). .

The partial strength reinforcing bar 51A includes a high-strength portion 311 disposed in the column base portion 10A and a high-strength region 310A along the column length direction from the column base portion 10A, and a normal strength portion 312 connected to the high-strength portion 311. It consists of and.
The normal strength reinforcing bar 51B is disposed in the normal strength region 310B located on the opposite side of the column base 10A across the high strength region 310A.
In the second embodiment, the high-strength portion 311 and the normal-strength portion 312 are composed of a single reinforcing bar. The high-strength portion 311 is manufactured by partially quenching one ordinary reinforcing bar (SD345) having the same strength as that of the normal-strength portion 312.

The method for designing the reinforced concrete structure in the second embodiment is the same as in the first embodiment.
FIG. 4A shows a design bending moment distribution. The design bending moment distribution of FIG. 4 (A) corresponds to the schematic diagram of the main bar 51 shown in FIG. 4 (B), and the design bending moment of the first embodiment shown in FIG. 3 (B). Same as distribution.
In the second embodiment, based on the design bending moment distribution shown in FIG. 4A, the position of the pillar 3 where the yield hinge Q is planned is set by the same method as in the first embodiment.
In the second embodiment, the same effects as in the first embodiment can be achieved.

[Third Embodiment]
A third embodiment of the present invention will be described with reference to FIGS.
The third embodiment is different from the first embodiment in the configuration of the pillar main reinforcement 61, and the other configurations are the same as those in the first embodiment.
As shown in FIG. 5, the column 6 includes a plurality of column main bars 61, a plurality of column reinforcing bars 32 that are arranged in the extending direction of the main bar 61 and reinforce the shear strength of the columns 6, and Is provided.
The column main reinforcement 61 includes a high-strength portion 611 whose lower end is coupled to the foundation 10C in a region including the column base portion 10A, and a normal-strength portion 312 connected to the high-strength portion 611.

The high-strength portions 611 are respectively disposed in the column base portion 10A and the high-strength regions 310A extending from the column base portion 10A along the column length direction.
The normal strength portion 312 has a normal strength reinforcing bar connected to the normal strength reinforcing bar 61A via a joint (not shown).
In the third embodiment, the amount of reinforcing bars of normal strength reinforcing bars arranged in the column base 10A and the high strength region 310A is larger than the amount of reinforcing bars of normal strength reinforcing bars arranged in the normal strength region 310B.

As shown in FIG. 6A, the high-strength portion 611 is composed of a normal strength reinforcing bar 61A and a reinforcing bar 61B.
The arrangement position of the normal strength reinforcing bar 61A in the horizontal cross section of the column 3 is along the outer periphery of the column 3, and the arrangement position of the reinforcing bar 61B in the horizontal cross section of the column 3 is closer to the center of the column than the normal strength reinforcing bar 61A. In FIG. 6A, the number of reinforcing bars 61B is four, but the specific number is set based on the design bending moment.
The normal strength reinforcing bar 61A and the reinforcing bar 61B are each composed of a normal reinforcing bar whose yield point or 0.2% proof stress is defined by JISG3112, and the yield point or 0.2% proof stress of the normal reinforcing bar is 295 MPa ( N / mm ² ) or more and 390 MPa (N / mm ² ) or less.

The design bending moment distribution shown in FIG. 6B is the same as the design bending moment distribution shown in FIG.
In the third embodiment, the amount of reinforcing bar 61B is calculated by the same method as in the first embodiment.
In the section of the dimension S from the base R of the column base 10A to the position of the yield hinge Q, the stress obtained by back calculation with respect to the bending moment of the base R of the column base 10A is less than the yield point of the reinforcing bar. The amount of reinforcing bars should be such that

Therefore, in the third embodiment, in addition to the same effects as (1) to (4) of the first embodiment, the following effects can be obtained.
(6) The number of reinforcing bars was increased from the normal strength region to form a high strength region. Therefore, the manufacturing cost of a reinforcing bar can be reduced compared with the case where the high strength part 311 is formed by quenching a part of one ordinary reinforcing bar.

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, in each said embodiment, although the position of the pillar 3 which plans the yield hinge Q was made into the junction location of the pillar 3 and the column base part 10A of the 1st floor part of a building, in this invention, it is limited to this. Instead, for example, as shown in FIG. 7, in addition to the junction between the pillar 3 and the column base 10A of the first floor of the building, or the joint of the pillar 3 and the column base 10A of the first floor of the building It is good also as a junction place of pillar 3 and pillar head 10B of the uppermost floor instead of. Furthermore, in the case where it is set that there is a column base 10A and a column head 10B for each floor, the connection between the column 3 and the column base or the connection between the column 3 and the column head on each floor or on a predetermined floor The location may be the position of the pillar 3 where the yield hinge Q is planned. Also in the example shown in FIG. 7, the position of the column for planning the yield hinge Q is set by the method of each embodiment.

  Moreover, although the said embodiment was applied to the building which has a flat roof, in this invention, as FIG. 8 shows, it can apply also to the building which has a step-like roof. Furthermore, in the said embodiment, although applied to the building where the height of the foundation 10C is the same, in this invention, as FIG. 9 shows, the building (building built in a sloping ground) where the height of the foundation 10C differs. Can be applied. In these buildings, the load applied to the column 3 is different at the position of the column base 10A. However, in the present invention, the columns 3 for which the yield hinge Q is planned for each column base 10A by the method of each embodiment described above. Will be determined.

Furthermore, in the present invention, as shown in FIGS. 10 and 11, the high-strength portion 311 is arranged such that the column base is sandwiched between the joint-side region including the column base portion 10 </ b> A and the normal strength portion 312. It is good also as a structure arrange | positioned in the pillar center side area | region located in the opposite side to the part 10A.
10 and 11 correspond to FIG. 3, respectively. In FIG. 10C, the high-strength portion 311 extending above the normal strength portion 312 is penetrated by the column beam joint portion 10 disposed above the column base portion 10A. In FIG. 11C, the high-strength portion 311 extending above the normal strength portion 312 stops at a position below the column-beam joint 10 disposed on the top of the column base 10A. Is penetrated by another normal strength portion 312. The high-strength portion 311 located above the normal-strength portion 312 is formed by partially quenching one ordinary rebar.

A plurality of main bars 31 in FIGS. 10C and 11C are arranged along the outer periphery of the pillar 3 like the main bars 31 in the first embodiment shown in FIG. . The design bending moment distribution shown in FIGS. 10B and 11B is the same as the design bending moment distribution shown in FIG. 3B, and the first bending moment distribution is based on the design bending moment distribution. The amount of reinforcing bars of the column main reinforcement 31 is calculated by the same method as in the embodiment.
In the example of FIGS. 10 and 11, 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 311 and the normal strength portion 312. Even if destruction concentrates on the boundary portion and fractures such as cracks try to diffuse toward the column center side, the high-strength portion 311 is arranged not only in the joint side region but also in the column center side region. Diffusion of destruction toward the center side is suppressed. In addition, in the example of FIG. 11, the high-strength portion 311 disposed in the column center side region is partially formed, so that the manufacturing cost can be reduced compared to the case where all the high-strength portions are formed.
In this invention, it can apply also to civil engineering structures, such as a bridge, besides a building structure.

  DESCRIPTION OF SYMBOLS 1 ... Reinforcement structure, 10 ... Column beam joint part, 10A ... Column base part, 10B ... Column head part, 10C ... Foundation, 2 ... Beam, 3, 5, 6 ... Column, 31, 51, 61 ... Main reinforcement, 310A ... High Strength region, 310B ... Normal strength region, 311, 611 ... High strength portion, 312 ... Normal strength portion, 4 ... Joint, Mu ... Bending moment on column base side, Q ... Yield hinge, R ... Base

Claims (7)

A plurality of pillar main bars joined to the beam, the pillar main bars having a normal strength portion and a high strength portion having a strength higher than that of the normal strength portion;
The high-strength portion includes at least one of a column base and a column head joined to the beam among the main reinforcing bars for the column, and a high strength along the column length direction from the column-beam joint. Placed in the area and
The ordinary strength portion is a method of designing a reinforced concrete structure located on the opposite side of the beam-to-column joint across the high strength region,
The position of the column for which the yield hinge is planned is set at the boundary between the high-strength portion and the normal-strength portion at a position away from the base portion of the beam-column joint ,
A design method for a reinforced concrete structure, characterized in that the high-strength portion is arranged in a column center side region opposite to the column-beam joint and the high-strength region across the normal strength portion . In the design method of the reinforced concrete structure described in Claim 1,
The method for designing a reinforced concrete structure, wherein the number of main bars for the column is calculated based on the design bending moment at the position of the yield hinge, based on the strength of the normal strength portion. In the design method of the reinforced concrete structure described in Claim 1 or Claim 2,
The method of designing a reinforced concrete structure, wherein stress of a reinforcing bar at a base portion of the beam-column joint is equal to or less than a standard yield point of the high-strength portion. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 3,
The high-strength portion and the normal-strength portion are connected to each other by a joint. In the design method of the reinforced concrete structure described in any one of Claims 1 thru | or 4,
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 is characterized in that the main reinforcing bar for the column is hardened to at least a part of one normal reinforcing bar having the same strength as that of the normal strength portion. In the design method of the reinforced concrete structure described in Claim 1 ,
A design method for a reinforced concrete structure in which a high-strength portion disposed in the central region of the column is partially formed. A reinforced concrete structure designed by the method for designing a reinforced concrete structure according to any one of claims 1 to 6 .

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