JP2015134992A - Wall column structure and building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wall column structure that improves the rotational rigidity and ductility of a column along with the rotational performance at the edge of a column member.SOLUTION: The structure of a reinforced concrete wall column 10 having a rectangular cross section has a taper 20 formed at the base part of a wall column 10 on both end sides in the longitudinal direction when seen on a horizontal cross-section, with the columnar cross-section increasing in the upward direction from the lower end surface of the wall column 10. On both end sides in the longitudinal direction of a horizontal cross-section of a throttle part 11, where the taper 20 of the wall column 10 has been formed, are disposed, respectively, axial reinforcements 31 at end parts and constraining shear reinforcements 42 that surround the axial reinforcements 31 at end parts.

Description

  The present invention relates to a structure of a wall pillar and a building provided with the wall pillar.

  Conventionally, in order to reduce damage to reinforced concrete columns during an earthquake, it has been proposed to reduce column cross-sectional area of column bases and improve column deformation performance, that is, rotation performance (see Patent Document 1).

Specifically, in the column base, the cross-sectional area of the column is decreased as it goes downward. In addition, in the portion where the column cross-sectional area decreases, an axial rebar that is fixed to the column and the lower structure is provided.
According to this proposal, since the column and the lower structure are semi-rigidly joined, it is possible to suppress damage caused by the rotational deformation of the column base during an earthquake and improve the rotation performance of the column.

JP 2009-079397 A

  However, in the above proposal, the rotational performance is improved, but the rotational rigidity (bending rigidity) of the column member is lowered. In addition, if a bending moment acts on a column during an earthquake, if an axial rebar is placed at the end of a horizontal section, the axial rebar on the compression side is likely to buckle, resulting in resistance to concrete only and less seismic energy absorption. . Therefore, there has been a demand for further improving the rotational rigidity (bending rigidity) of the column and further the toughness performance (energy absorption performance).

  In particular, in a wall column with a horizontal cross section of a rectangle, the rotational rigidity (bending rigidity) of the column is greater in the long side direction than in the short side direction, but the deformation performance is greater in the long side direction than in the short side direction. Inferior. Therefore, when an external load is applied from any direction due to an earthquake, damage concentrates on the concrete and the reinforcing bar at the end of the column base in the long side direction. Therefore, the wall column is particularly required to improve toughness.

  An object of the present invention is to provide a wall column structure capable of improving the rotational rigidity and toughness of a column while improving the rotational performance of the column member end.

  The wall column structure according to claim 1 is a structure of a reinforced concrete wall column (for example, a wall column 10, 10A, 10B, 10C described later) having a rectangular cross section, and a vertical member end of the wall column. The taper (for example, a taper 20 to be described later) in which the cross-sectional area of the wall column increases from the member end of the wall column toward the vertical center is formed at both ends in the long side direction as viewed in a horizontal section. In the portion of the wall column where the taper is formed (for example, a narrowed portion 11 to be described later), a large-diameter axial rebar (for example, an end portion to be described later) is provided at both ends in the long side direction of the horizontal section of the member end portion. Axial reinforcing bars 31, 31 </ b> A, and 31 </ b> B) and a constrained shear reinforcing bar (for example, a constraining shear reinforcing bar 42 described later) disposed so as to surround the large-diameter axial reinforcing bar are provided.

According to this invention, the length of the wall column is tapered at the end of the member in the vertical direction, and the column cross-sectional area is increased from the end of the wall column toward the center in the vertical direction.
During an earthquake, a bending moment and a shearing force act on the wall column. Due to the bending moment at the time of the earthquake, a part of the end surface of the wall column becomes a compression region where compressive stress is generated. At this time, a peripheral region is secured in the vicinity of the compression region, and a part of the peripheral region becomes a constraining region for constraining the concrete (Imai et al., Compression characteristics and bending strength of concrete at the end of the RC member, Architectural Institute of Japan (Refer to the publication of structural system, No. 587, pp.189-196, 2005.1). As a result, the concrete in the compression region is less likely to be collapsed, so that damage to the column housing accompanying rotation of the column member end portion can be suppressed, and the yield strength can be secured stably even when the rotation angle of the member end portion increases. In addition, as described above, since a stable rotation performance can be obtained even if the column is flat, it is possible to configure a frame combined with a damper or the like.

Moreover, since the horizontal cross-sectional area is larger in the portion not provided with the taper than in the portion provided with the taper, the degree of shear stress to be held is reduced, and damage due to shear cracks can be suppressed.
In addition, the wall column can maintain high rotational rigidity because the horizontal cross section is flatter than the general column having a square or circular horizontal cross section even in the tapered portion.

  Moreover, the large diameter axial direction reinforcing bar was provided in each of the both ends of the long side direction of the horizontal cross section of the part in which the taper was formed, and this large diameter axial direction reinforcing bar was enclosed by the restraining shear reinforcement. Therefore, when a compressive force acts on the large-diameter axial rebar due to the bending moment during an earthquake, the large-diameter axial rebar is restrained by this constrained shear reinforcement in the part surrounded by this constrained shear reinforcement, In addition, it is possible to yield in compression, and energy can be absorbed efficiently and economically.

  This is because the concrete is able to bear a compressive stress stably without collapsing even though the amount of strain increases due to the restraint by the restraint shear reinforcement and the strong restraint due to the change in the horizontal section of the wall column. This is because the axial rebar does not buckle and stably resists up to a region where the amount of strain is large enough to yield compression.

In particular, since the axial rebars at both ends in the long side direction have a large diameter, the large diameter axial rebar is restrained by a restraining shear reinforcement and the axial rebar is subjected to compressive force. It can yield and absorb energy without yielding.
Therefore, it is possible to provide a column structure having high rotational rigidity (bending rigidity) and excellent toughness performance (energy absorption performance). As a result, damage to the column base during an earthquake can be reduced.

  In the wall column structure of claim 2, the wall column includes a constrained axial reinforcing bar (for example, a constraining axial rebar 32 described later) and a peripheral axial rebar (for example, a peripheral axial rebar described below) extending in the axial direction. 33), and the restraint axial rebar and the peripheral axial rebar are fixed in the wall column.

  The wall column structure according to claim 3 is configured such that the large-diameter axial reinforcing bar has an annular shape of the restrained shear reinforcing bar and the second shear reinforcing bar (for example, a second shear reinforcing bar described later) from the side closer to the large-diameter axial reinforcing bar. It is characterized by being surrounded in triplicate by a reinforcement 41) and a shear reinforcement (for example, a shear reinforcement 40 described later).

  According to the present invention, in the strongly constrained region C, a rectangular concrete body in which a large-diameter axial reinforcing bar is disposed near the center is tripled by an annular constrained shear reinforcing bar, a second shear reinforcing bar, and a shear reinforcing bar. Since it is restrained by surrounding it, damage to the concrete body and cracking can be suppressed.

  Here, it is preferable that the large-diameter axial rebar is fixed to a housing (for example, a support housing 4 described later) that penetrates the horizontal section of the end portion of the wall column and is joined to the wall column. .

  The stress transmission in the horizontal section at the end of the member must be borne by the large-diameter axial rebar. Therefore, according to the present invention, the large-diameter axial reinforcing bar penetrates the horizontal cross section of the end portion of the wall column and is fixed to the housing joined to the wall column. Thereby, the large diameter axial direction reinforcing bar can bear the stress transmission in the horizontal section of the member end.

  In the wall column structure of the present invention, a second large-diameter axial reinforcing bar (for example, central axial reinforcing rods 30 and 30A described later) is provided in the central portion in the long side direction of the portion where the taper of the wall column is formed. 30B) is preferably provided.

  According to the present invention, the second large-diameter axial reinforcing bar is provided at the central portion in the long side direction of the portion where the taper of the wall column is formed. Unlike the large axial rebars at both ends, the second large axial rebar at the center does not yield due to compressive stress, so it has the effect of restoring (restoring) the rotation of the column end of the column. As a result, residual deformation of the entire building can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the rotational rigidity and toughness of a pillar can be improved, improving the rotational performance of the member edge part of a pillar.

1 is a plan view of a building to which a wall pillar structure according to a first embodiment of the present invention is applied. It is the front view, side view, and looking-up figure of the column base part of the wall pillar which concerns on the said embodiment. It is a sectional side view of the column base part of the wall pillar which concerns on the said embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a figure which shows stress distribution when a bending moment acts on the wall pillar which concerns on the said embodiment. It is a figure which shows the material end rotation angle when a horizontal load acts on the wall pillar which concerns on the said embodiment. It is a sectional side view of the column base part of the wall pillar which concerns on 2nd Embodiment of this invention. It is CC sectional drawing of FIG. It is DD sectional drawing of FIG. It is the front view, side view, and looking-up figure of the column base part of the wall pillar which concerns on the modification of this invention. It is the front view, side view, and looking-up figure of the column base part of the wall pillar which concerns on another modification of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[First Embodiment]
FIG. 1 is a plan view of a building 1 to which a wall pillar structure according to a first embodiment of the present invention is applied.
The building 1 includes a core frame 2 disposed substantially at the center of the building and an outer frame 3 provided along the outer periphery of the building.
The outer frame 3 includes reinforced concrete wall columns 10 provided at predetermined intervals along the outer wall surface of the building.

FIG. 2 is a front view, a side view, and a look-up view of the column base portion of the wall column 10. FIG. 3 is a side sectional view of the column base portion of the wall column 10. 4 is a cross-sectional view taken along line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG.
The wall column 10 has a rectangular cross section and is provided on the support housing 4. At the column base of the wall column 10 and at both ends in the long side direction in a horizontal sectional view, the column breaks from the lower end surface, which is a member end of the wall column 10, toward the vertical center, that is, upward. A linear taper 20 having an increased area is formed.
The angle of the taper 20 is preferably 45 degrees or less with respect to the horizontal plane, and is 30 degrees here.

Hereinafter, the portion of the wall pillar 10 where the taper 20 is formed is referred to as a throttle portion 11, and the other portion is referred to as a general portion 12.
At the lower end of the narrowed portion 11, the ratio of the long side to the short side in the horizontal cross section is preferably about 1.5 to 5.0. Moreover, in the general part 12, the ratio of the long side to the short side in the horizontal section is preferably about 3.0 or more.

  The wall column 10 extends in the axial direction and is fixed to the support housing 4 at the central axial rebar 30 as the second large-diameter axial rebar, the end axial rebar 31 as the large-diameter axial rebar, and the thin Warp constrained axial reinforcing bars 32, axial peripheral reinforcing bars 33 extending in the axial direction and not fixed to the support housing 4, and shear reinforcing bars 40 provided in the general portion 12 at predetermined intervals in the vertical direction A second shear reinforcement bar 41 provided at a predetermined interval in the vertical direction on a portion of the general part 12 near the throttle unit 11; and a restrained shear reinforcement bar 42 provided on the throttle unit 11 at a predetermined interval in the vertical direction. .

  The central axial rebar 30 is one and penetrates through the throttle portion 11 and is fixed to the support housing 4. The central axial rebar 30 is disposed at the central portion in the long side direction and the central portion in the short side direction of the throttle portion 11 in a horizontal sectional view.

  There are two end axial rebars 31 that pass through the throttle portion 11 and are fixed to the support housing 4. These end axial rebars 31 are arranged at both ends in the long side direction and at the center in the short side direction of the throttle unit 11 in a horizontal sectional view.

A plurality of the constraining axis direction reinforcing bars 32 are arranged along the peripheral edge portion of the throttle portion 11 in a horizontal sectional view.
The peripheral axial rebars 33 are arranged at the four corners of the general part 12 in a horizontal sectional view.

  The above-described large-diameter axial rebars 30 and 31 are preferably about D25 to D41, and the small-diameter axial rebars 32 and 33 are preferably about D10 to D16.

The shear reinforcing bar 40 is an annular shape that surrounds the central axial reinforcing bar 30, the end axial reinforcing bar 31, the constraining axial reinforcing bar 32, and the peripheral axial reinforcing bar 33.
The second shear reinforcing bar 41 is an annular shape that surrounds the central axial reinforcing bar 30, the end axial reinforcing bar 31, and the restraining axial reinforcing bar 32, and is provided between the shear reinforcing bars 40.
The constraining shear reinforcing bar 42 is arranged in an annular shape so as to surround the end axial reinforcing bar 31 and the constraining axial reinforcing bar 32.

The restraining shear reinforcement bars 42 are provided at regular intervals within a predetermined range from the member end of the wall column 10 to the vertical center of the wall column 10.
The predetermined range is a vertical height including a strongly constrained region in a state of high compressive stress at the end of the wall column 10 caused by an earthquake, and is a height from the member end of the wall column 10.

  This predetermined range may be, for example, approximately the length of the long side of the lower end of the aperture 11. That is, the constrained shear reinforcement need not be provided over the entire length of the wall column 10.

  As described above, the end axial reinforcing bar 31 is triple-wrapped by the annular restrained shear reinforcing bar 42, the second shear reinforcing bar 41, and the shear reinforcing bar 40 from the side closer to the end axial reinforcing bar 31. .

According to this embodiment, there are the following effects.
(1) The taper 20 was provided in the column base part of the wall column 10, and the column cross-sectional area was increased toward the upper part from the lower end part of the wall column 10. As shown in FIG.
During an earthquake, a bending moment and a shearing force are applied to the wall column 10, but due to the bending moment at the time of the earthquake, as shown in FIG. 6, a part of the lower end surface of the wall column 10 is compressed to generate a compressive stress. It becomes area 13A. At this time, a peripheral region 13B is secured in the vicinity of the compression region 13A, and a part of the peripheral region 13B becomes a strong restraint region 13C that restrains concrete. As a result, the concrete in the compressed region 13A is not easily crushed, so that damage to the column housing due to the rotation of the column base can be suppressed, and the yield strength can be stably secured even when the rotation angle of the column base increases. In addition, as described above, since a stable rotation performance can be obtained even if the column is flat, it is possible to configure a frame combined with a damper or the like.

Further, since the general section 12 has a larger horizontal cross-sectional area than the throttle section 11, the degree of shear stress to be held is reduced, and damage due to shear cracks can be suppressed.
Moreover, as shown in FIG. 7, since the horizontal cross section of the general part 12 and the aperture | diaphragm | squeeze part 11 is flat, the wall pillar 10 has high rotation compared with the general pillar whose horizontal cross section is square shape or circular shape. The rigidity can be maintained. FIG. 7 is a diagram showing the relationship between the horizontal load Q and the material end rotation angle R for a general wall column without a taper, a wall column of the present invention, and a general column that is not flat.

  Further, a large-diameter end axial reinforcing bar 31 is provided at each of both ends in the long side direction of the narrowed portion 11, and the end axial reinforcing bar 31 is surrounded by an annular constrained shear reinforcing bar 42 and a constraining axial reinforcing bar 32. . Therefore, when a compressive force is applied to the end axial rebar 31 due to the bending moment at the time of the earthquake, the end axial rebar 31 is restrained sheared in the portion surrounded by the restraint shear reinforcing bar 42 and the restraint axial rebar 32. It is restrained by the reinforcing bar 42 and the restraining axial direction reinforcing bar 32 and can yield not only in tension but also in compression, and energy can be absorbed efficiently and economically.

In particular, since the end axial rebars 31 at both ends in the long side direction have a large diameter, the large end axial rebars 31 are restrained by the restraining shear reinforcing bars 42, and the axial rebars 31 are compressed. Even if it receives, it can yield and absorb energy stably without buckling.
Therefore, it is possible to provide a column structure having high rotational rigidity (bending rigidity) and excellent toughness performance (energy absorption performance). As a result, damage to the column base during an earthquake can be reduced.

(2) In the strong restraint region 13 </ b> C, a rectangular concrete body in which the end axial rebars 31 are arranged near the center is formed by an annular restraint shear reinforcement 42, second shear reinforcement 41, and shear reinforcement 40. Since it is restrained by surrounding it in triplicate, damage to the concrete body and generation of cracks can be suppressed.
The annular constrained shear reinforcement bar 42 and the second shear reinforcement bar 41 have a shear reinforcement effect on the end critical section and the member center section.

(3) The large-diameter axial rebars 30 and 31 are fixed to the support case 4 that penetrates the horizontal section of the end portion of the wall column 10 and is joined to the wall column 10. Thereby, the large diameter axial direction reinforcing bars 30 and 31 can bear the stress transmission in the horizontal section of the member end.
Here, the constraining axial direction reinforcing bars 32 and 32A do not necessarily have to penetrate the horizontal section of the member end. If the constrained axial rebars 32 and 32A are not required in the horizontal cross section at the member end in terms of structural performance and construction, only the large-diameter axial rebars 30 and 31 are horizontal cross sections at the end of the member as in this embodiment May be fixed to the support housing 4 through the substrate.

  (4) The central portion axial rebar 30 is provided in the central portion in the long side direction of the narrowed portion 11 of the wall column 10. Since the central axial rebar 30 is not yielded by compressive stress unlike the end axial rebar 31 at both ends, the effect of returning (restoring) the rotation of the column base can be exhibited. The residual deformation of can be reduced.

  (5) Since the central axial reinforcing bar 30 and the end axial reinforcing bar 31 are arranged near the center in the short side direction of the wall column 10, they are hardly affected by the bending in the short side direction and resist bending in the long side direction. As a seismic element, design with a clear role is possible.

  (6) Since the thick central axial reinforcing bar 30 and the end axial reinforcing bar 31 are arranged in the central part in the short side direction of the wall column 10 surrounded by the restraining shear reinforcing bar 42 and the second shear reinforcing bar 41. A sufficient concrete covering thickness can be secured around the axial reinforcing bars 30, 31 and the concrete is restrained by a shear reinforcing bar, thereby acting between the axial reinforcing bars 30, 31 and the surrounding concrete. The shearing force (adhesion force) can be suppressed, and the occurrence of adhesion split cracks can be suppressed.

  (7) By making the axial rebars 30 and 31 have a large diameter, it is possible to reduce the adhesion stress generated on the entire circumferential surface of the rebar. Further, since the large-diameter axial rebars 30 and 31 have a large cross-sectional area of the rebar compared to a rebar having a common diameter, the degree of restraint by the concrete around the rebar is large, and the buckling length is shortened. , Can bear a large axial force. In this embodiment, about D25-D41 is assumed as the thick axial rebars 30,31.

  (8) Since the second shear reinforcement bars 41 need only be concentrated in the vicinity of the narrowed portion 11 having a high shear stress level, the shear reinforcement bars can be reduced, which is economical.

[Second Embodiment]
FIG. 8 is a side sectional view of the column base portion of the wall column 10A according to the second embodiment of the present invention. 9 is a cross-sectional view taken along the line CC of FIG. 10 is a cross-sectional view taken along the line DD of FIG.
In the present embodiment, the structure of the wall pillar 10A is different from that of the first embodiment.

That is, the wall column 10A is precast concrete, and the central axial reinforcing bar 30A, the end axial reinforcing bar 31A, and the constraining axial reinforcing bar 32A are not fixed to the support housing 4.
The central axial reinforcing bar 30A and the end axial reinforcing bar 31A are joined to the central axial reinforcing bar 30B and the end axial reinforcing bar 31B of the support housing 4 by a mechanical joint 34 in the throttle portion 11.

Even if it does in this way, in addition to the effect similar to the above-mentioned (1)-(8), there exist the following effects.
(9) Since the central axial rebar 30A and the end axial rebar 31A are arranged in the central portion in the short side direction in a horizontal sectional view, the mechanical joint 34 can be easily provided and the workability is excellent. .

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

  For example, in each of the above-described embodiments, the taper 20 is provided only at both ends in the long side direction of the wall pillars 10 and 10A in the horizontal sectional view, but not limited thereto, as shown in FIG. You may provide also in the short side direction both ends of the wall pillar 10B. If it does in this way, also about the short side direction of a wall column, damage to the column housing accompanying rotation of a column end part is suppressed, and even if the rotation angle of a column end part becomes large, proof stress can be secured stably.

  Further, in each of the above-described embodiments, the taper 20 is linear, but the present invention is not limited to this, and may be an arc having a radius R as shown in FIG.

  Further, in each of the above-described embodiments, one end axial rebar 31, 31A, 31B is disposed at each end of the horizontal cross section, and the central axial rebar 30, 30A, 30B is disposed at the center of the horizontal cross section. Although only one is provided, the present invention is not limited to this, and a plurality of them may be arranged.

  Further, in each of the above-described embodiments, the wall pillars 10, 10A, 10B, and 10C are wall pillars that extend in one direction in a horizontal section. However, the present invention is not limited to this, and the wall pillars have a cross-shaped horizontal section. Thus, they may be provided in two directions orthogonal to each other on the plane, that is, in the XY direction.

  Further, in each of the above-described embodiments, the restraining axial direction reinforcing bar 32 is fixed to the support housing 4. However, the present invention is not limited thereto, and the restraining axial direction reinforcing bar is fixed to the wall column 10 and is not fixed to the supporting housing 4. May be.

DESCRIPTION OF SYMBOLS 1 ... Building 2 ... Core frame 3 ... Outer frame 4 ... Supporting frame 10, 10A, 10B, 10C ... Wall pillar 11 ... Restriction part 12 ... General part 13A ... Compression area 13B ... Peripheral area 13C ... Strong restraint area 20 ... Taper 30 , 30A, 30B ... central part axial rebar (second large diameter axial rebar)
31, 31A, 31B ... end axial reinforcing bars (large diameter axial reinforcing bars)
32, 32A: Restraint axial reinforcement 33 ... Peripheral axial reinforcement 34 ... Mechanical joint 40 ... Shear reinforcement 41 ... Second shear reinforcement 42 ... Restraint shear reinforcement

Claims (4)

A reinforced concrete wall column structure having a rectangular cross section,
At the end of the wall column in the vertical direction and at both ends in the long side direction as viewed in horizontal section, a taper is formed in which the column cross-sectional area increases from the member end of the wall column toward the vertical center,
In the part where the taper is formed, a large-diameter axial reinforcing bar and a constrained shear reinforcing bar arranged around the large-diameter axial reinforcing bar at both ends in the long side direction of the horizontal cross section of the member end part, respectively. A wall pillar structure characterized by being provided with.   The wall column is provided with a constraining axial reinforcing bar and a peripheral axial reinforcing bar extending in the axial direction, and the constraining axial reinforcing bar and the peripheral axial reinforcing bar are fixed in the wall column. The wall pillar structure according to claim 1.   The large-diameter axial reinforcing bar is triple-wrapped by the annular restraining shear reinforcing bar, the second shear reinforcing bar, and the shear reinforcing bar from the side close to the large-diameter axial bar. Item 3. A wall column structure according to item 1 or 2.   A building comprising the wall pillar structure according to any one of claims 1 to 3.

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