JP7795960B2 - Shear walls and structures - Google Patents
Shear walls and structuresInfo
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- JP7795960B2 JP7795960B2 JP2022069787A JP2022069787A JP7795960B2 JP 7795960 B2 JP7795960 B2 JP 7795960B2 JP 2022069787 A JP2022069787 A JP 2022069787A JP 2022069787 A JP2022069787 A JP 2022069787A JP 7795960 B2 JP7795960 B2 JP 7795960B2
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Description
本発明は、繊維が混入された鉄筋コンクリート造の耐力壁、および、この耐力壁を備える構造物に関する。 The present invention relates to a reinforced concrete shear wall containing fibers, and a structure equipped with this shear wall.
従来より、鉄筋コンクリート造（ＲＣ造）の壁部と、この壁部の一端側に設けられたＲＣ造の柱部と、を備える耐力壁がある（特許文献１、２参照）。
特許文献１には、高層建造物における連層耐震壁構造が示されている。連層耐震壁は、壁板部と付帯柱とを備え、上下に連続して複数配置されている。
特許文献２には、補強壁と、この補強壁に接合されたコンクリート建築物の柱と、を含む建築物の補強構造が示されている。補強壁は、繊維含有水硬性組成物の硬化体からなるパネルと、パネルと柱との間に形成された接合部と、からなる。
非特許文献１には、一般的なコンクリートを用いたＲＣ造耐力壁の塑性変形能力について判別方法が記載されている。付帯柱を有するＲＣ造耐力壁の場合、付帯柱が無いＲＣ造耐力壁に比べて、靭性能を高く評価可能である反面、前記判別方法に基づき高い塑性変形能力を期待するには付帯柱の幅を壁厚の２倍以上とする必要があった。よって、付帯柱を有するＲＣ造耐力壁では、付帯柱の幅を壁厚の２倍以上とする場合が多く、建築物の床面積が削減されることで、使い勝手の良い室内空間が確保出来ない場合があった。
BACKGROUND ART Conventionally, there has been a bearing wall having a wall portion made of reinforced concrete (RC) and a column portion made of RC provided on one end side of the wall portion (see Patent Documents 1 and 2).
Patent Document 1 discloses a multi-story earthquake-resistant wall structure for a high-rise building. The multi-story earthquake-resistant wall includes wall panels and auxiliary columns, and is arranged vertically in succession.
Patent Document 2 discloses a reinforced structure for a building that includes a reinforced wall and a column of a concrete building joined to the reinforced wall. The reinforced wall is composed of a panel made of a hardened fiber-containing hydraulic composition and a joint formed between the panel and the column.
Non-Patent Document 1 describes a method for determining the plastic deformation capacity of reinforced concrete shear walls made of ordinary concrete. While reinforced concrete shear walls with auxiliary columns can be evaluated for ductility performance higher than reinforced concrete shear walls without such columns, the width of the auxiliary columns must be at least twice the wall thickness to achieve high plastic deformation capacity based on the method. Therefore, in reinforced concrete shear walls with auxiliary columns, the width of the auxiliary columns is often set to at least twice the wall thickness, which reduces the floor area of the building and can make it difficult to ensure a user-friendly interior space.
本発明は、耐力壁の柱部の幅を小さくしつつ、耐力と変形性能に優れた耐力壁、および、その耐力壁を用いた構造物を提供することを課題とする。 The objective of the present invention is to provide a bearing wall that has excellent strength and deformation performance while reducing the width of the column portion of the bearing wall, and to provide a structure that uses such a bearing wall.
本発明者らは、耐力壁の壁部および柱部を形成するコンクリートに、繊維をコンクリート体積の０.３％以上１．５％以下混入することで、繊維によりせん断補強筋と同等以上の補強効果が得られて、壁部や柱部にせん断補強筋を過密に配筋する必要がない点に着眼して、本発明に至った。
第１の発明の耐力壁（例えば、後述の耐力壁１０）は、鉄筋コンクリート造の耐力壁であって、鉄筋コンクリート造の壁部（例えば、後述の壁部２０）と、前記壁部の水平方向端部に設けられる鉄筋コンクリート造の柱部（例えば、後述の柱部３０）と、を備え、前記壁部および前記柱部のコンクリート体（例えば、後述のコンクリート体２１、３１）は、繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成され、前記柱部の幅は、前記壁部の壁厚の１倍以上２倍未満であることを特徴とする。
The inventors arrived at this invention by noting that by mixing fibers into the concrete that forms the walls and columns of a shear wall in an amount of 0.3% to 1.5% by volume of concrete, the fibers can provide a reinforcing effect equal to or greater than that of shear reinforcement, eliminating the need to densely arrange shear reinforcement in the walls and columns.
The shear wall of the first invention (for example, shear wall 10 described below) is a shear wall made of reinforced concrete, and comprises a wall portion made of reinforced concrete (for example, wall portion 20 described below) and a column portion made of reinforced concrete (for example, column portion 30 described below) provided at the horizontal end of the wall portion, and the concrete bodies of the wall portion and the column portion (for example, concrete bodies 21, 31 described below) are formed of fiber-reinforced concrete containing fibers in an amount of 0.3% to 1.5% by volume of concrete, and the width of the column portion is at least 1 time but less than 2 times the wall thickness of the wall portion.
この発明によれば、壁部および柱部を含んで耐力壁を構成し、これら壁部および柱部を、繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成した。よって、繊維がせん断補強筋と同等以上の補強効果を発揮するため、壁部や柱部にせん断補強筋を過密に配筋する必要がない。
その結果、柱部の幅を壁部の壁厚の１倍以上２倍未満と小さくして、使い勝手の良い室内空間を確保しつつ、耐力と変形性能に優れた耐力壁を実現できる。
また、普通コンクリートではなく繊維補強コンクリートを用いて、壁部および柱部のコンクリート体を構築したので、施工性が良い。
また、柱部を繊維補強コンクリートで形成したので、柱部の変形性能が向上するため、柱部の幅を壁部の壁厚の１倍以上２倍未満としても優れた変形性能を確保できる。よって、非特許文献１に示すような従来の規定に従って柱幅を壁厚の２倍以上とする必要がなくなった。その結果、整形な平面形状の室を計画しやすくなり、建築物の床面積を従来よりも大きくすることができるので、使い勝手の良い室内空間を確保することが可能となった。
また、繊維補強コンクリートは、普通コンクリートに繊維を加えるのみでよいため、コンクリート練り混ぜ時に繊維を混入し攪拌することで製造できる。これは、特許文献１のように、靭性能や耐力確保のための部材を別に施工する場合に比べて、簡易であり、施工性が良い。
例えば、壁部の断面積に対する横筋および縦筋の断面積の割合（鉄筋比）を０.３％または０．５９％とし、壁部および柱部を、コンクリート体積に対して鋼繊維を０.５％または１．０％混入した繊維補強コンクリートで形成した場合、繊維が混入されていない普通コンクリートで壁部および柱部を形成した場合に比べて、せん断耐力を約１.１～１．１８倍に増大させることができるうえに、最大耐力後の耐力の急減な低下を防止でき、変形性能を向上させることができる。
According to this invention, a bearing wall is constructed including wall sections and columns, and these wall sections and columns are formed from fiber-reinforced concrete containing 0.3% to 1.5% of fiber by volume of concrete. Therefore, since the fiber exerts a reinforcing effect equal to or greater than that of shear reinforcement, there is no need to arrange shear reinforcement bars densely in the wall sections and columns.
As a result, the width of the column can be reduced to between one and two times the thickness of the wall, ensuring a user-friendly interior space while achieving a bearing wall with excellent strength and deformation performance.
In addition, the concrete bodies of the walls and columns were constructed using fiber-reinforced concrete instead of ordinary concrete, making construction easy.
Furthermore, because the columns are made of fiber-reinforced concrete, their deformation performance is improved, ensuring excellent deformation performance even when the column width is between one and two times the wall thickness. This eliminates the need to make the column width at least twice the wall thickness as in the conventional regulations shown in Non-Patent Document 1. As a result, it has become easier to plan rooms with regular plan shapes, and the floor area of buildings can be increased compared to conventional methods, making it possible to ensure user-friendly interior spaces.
Furthermore, fiber-reinforced concrete can be produced by simply adding fibers to ordinary concrete and mixing the fibers during the concrete mix. This is simpler and easier to work with than the method described in Patent Document 1, in which separate components are installed to ensure toughness and strength.
For example, if the ratio of the cross-sectional area of the horizontal and vertical reinforcement to the cross-sectional area of the wall (reinforcement ratio) is 0.3% or 0.59%, and the walls and columns are made of fiber-reinforced concrete with 0.5% or 1.0% steel fiber mixed in with respect to the concrete volume, the shear strength can be increased by approximately 1.1 to 1.18 times compared to when the walls and columns are made of ordinary concrete with no fibers mixed in. In addition, a sudden decrease in strength after the maximum strength can be prevented, and deformation performance can be improved.
第２の発明の耐力壁は、前記繊維は、両端部が折り曲げられた鋼繊維であることを特徴とする。
この発明によれば、繊維補強コンクリートに混入する繊維として、両端部が折り曲げられた鋼繊維を用いたので、鋼繊維の折り曲げ部でコンクリートと鋼繊維との間の付着性能が高まる。
また、鋼繊維の熱膨張係数は、コンクリートとほぼ等しいので、温度変化により生じる内部応力を低減可能であり、鋼繊維とコンクリートの一体性を確保することができる。
The shear wall of the second invention is characterized in that the fibers are steel fibers with both ends bent.
According to this invention, steel fibers with bent ends are used as the fibers to be mixed into the fiber-reinforced concrete, and therefore the bent portions of the steel fibers improve the adhesion between the concrete and the steel fibers.
Furthermore, since the thermal expansion coefficient of steel fibers is approximately equal to that of concrete, it is possible to reduce internal stress caused by temperature changes, and to ensure the integrity of the steel fibers and concrete.
第３の発明の構造物（例えば、後述の建物１）は、上述の鉄筋コンクリート造の耐力壁を備える構造物であって、前記耐力壁の上側または下側には、別の耐力壁（例えば、後述の耐力壁１０Ａ）が配置され、前記別の耐力壁は、繊維が混入されていない鉄筋コンクリート造の壁部（例えば、後述の壁部２０）と、前記壁部の水平方向端部に設けられる、繊維が混入されていない鉄筋コンクリート造の柱部（例えば、後述の柱部３０）と、を備え、前記耐力壁の壁部の縦筋（例えば、後述の縦筋２２）は、前記別の耐力壁の壁部の縦筋に接合され、前記耐力壁の柱部の柱主筋（例えば、後述の柱主筋３２）は、前記別の耐力壁の柱部の柱主筋に接合されていることを特徴とする。 A structure of the third invention (for example, building 1 described below) is a structure comprising the above-mentioned reinforced concrete shear wall, with another shear wall (for example, shear wall 10A described below) placed above or below the shear wall, and the other shear wall comprising a wall section (for example, wall section 20 described below) made of reinforced concrete without fiber mixed in, and a column section (for example, column section 30 described below) made of reinforced concrete without fiber mixed in, provided at the horizontal end of the wall section, with the vertical reinforcement of the wall section of the shear wall (for example, vertical reinforcement 22 described below) joined to the vertical reinforcement of the wall section of the other shear wall, and the column main reinforcement of the column of the shear wall (for example, column main reinforcement 32 described below) joined to the column main reinforcement of the column of the other shear wall.
ここで、耐力壁および別の耐力壁は、構造物の地上階または地下階のいずれに設けてもよい。
この発明によれば、繊維補強コンクリートで形成された耐力壁の上側または下側に、繊維が混入されていないコンクリートで形成された別の耐力壁を設けるとともに、双方の壁の縦筋および柱主筋同士を接合した。よって、構造物の全ての階に繊維補強コンクリートで形成された耐力壁を設けなくても、大きい荷重を受ける部位や靭性能が求められる部位に繊維補強コンクリートで形成された耐力壁を用いることで、せん断耐力および変形性能に優れた構造物を実現できる。
Here, the load-bearing wall and the other load-bearing wall may be provided on either the ground floor or the basement floor of the structure.
According to this invention, a bearing wall made of concrete without fibers is installed above or below a bearing wall made of fiber-reinforced concrete, and the vertical reinforcement and main column reinforcement of both walls are connected to each other. Therefore, even if bearing walls made of fiber-reinforced concrete are not installed on every floor of a structure, by using bearing walls made of fiber-reinforced concrete in areas that are subject to large loads or where toughness is required, a structure with excellent shear strength and deformation performance can be realized.
本発明によれば、耐力壁の柱部の幅を小さくしつつ、耐力と変形性能に優れた耐力壁、および、その耐力壁を用いた構造物を提供できる。 The present invention makes it possible to provide a bearing wall that has excellent strength and deformation performance while reducing the width of the column portion of the bearing wall, as well as a structure that uses such a bearing wall.
本発明は、繊維が混入された鉄筋コンクリート造の壁部および柱部を有する耐力壁であり、これら壁部および柱部のコンクリート体を、繊維をコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成することで、柱部の幅を壁部の壁厚の１倍以上２倍未満にした（図１～図６）。また、本発明の耐力壁を備える構造物では、繊維が混入された鉄筋コンクリート造の耐力壁の上側または下側に、繊維が混入されていない鉄筋コンクリート造の別の耐力壁が配置され、双方の耐力壁を形成する柱主筋および壁縦筋が互いに接合されている。
以下、本発明の一実施形態について、図面を参照しながら説明する。
図１は、本発明の一実施形態に係る耐力壁１０が適用された構造物としての建物１の所定階の平面図である。図２は、図１の建物１のＡ－Ａ断面図である。
建物１は、複数層を有する鉄筋コンクリート造の建物であり、鉛直方向に延びる複数の柱２と、複数の柱２の頂部同士を連結する複数の梁３と、複数の梁３に支持された図示しない床と、を備える。
平面視で、建物１の中央部であるコア部には、上下に連続して複数の耐力壁１０、１０Ａが配置されている。これら耐力壁１０、１０Ａは、複数層に亘って配置されて、連層耐震壁となっている。
各耐力壁１０は、壁部２０と、壁部２０の端部に沿って鉛直方向に延びる柱部３０と、を備える。つまり、コア部に配置された柱２は、壁部２０に接合された柱部３０となっている。
The present invention is a shear wall having wall and column sections made of fiber-reinforced concrete, and the concrete bodies of these wall and column sections are made of fiber-reinforced concrete containing 0.3% to 1.5% of fiber by volume of the concrete, so that the width of the column sections is at least one time but less than two times the wall thickness of the wall sections (Figs. 1 to 6). Also, in a structure equipped with the shear wall of the present invention, a shear wall made of fiber-reinforced concrete is placed above or below another shear wall made of non-fiber-reinforced concrete, and the main column reinforcement bars and vertical wall reinforcement bars of both shear walls are joined to each other.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a plan view of a predetermined floor of a building 1 as a structure to which a bearing wall 10 according to one embodiment of the present invention is applied. Fig. 2 is a cross-sectional view of the building 1 taken along line AA in Fig. 1.
The building 1 is a reinforced concrete building having multiple floors, and comprises a plurality of columns 2 extending vertically, a plurality of beams 3 connecting the tops of the columns 2, and a floor (not shown) supported by the beams 3.
In plan view, a plurality of shear walls 10, 10A are arranged vertically in succession in the core portion, which is the central portion of the building 1. These shear walls 10, 10A are arranged across multiple stories to form a multi-story earthquake-resistant wall.
Each bearing wall 10 includes a wall portion 20 and a column portion 30 extending vertically along the end of the wall portion 20. In other words, the column 2 arranged in the core portion is the column portion 30 joined to the wall portion 20.
図３は、耐力壁１０の正面図である。図４は、図３の耐力壁１０のＢ－Ｂ断面図である。図５は、図３の耐力壁１０のＣ－Ｃ断面図およびＤ－Ｄ断面図である。
壁部２０は、繊維が混入された繊維補強コンクリートで形成されたコンクリート体２１と、コンクリート体２１に埋設されて鉛直方向に延びる縦筋２２と、コンクリート体２１に埋設されて水平方向に延びる横筋２３と、を備える。
柱部３０は、繊維が混入された繊維補強コンクリートで形成されたコンクリート体３１と、コンクリート体３１に埋設されて鉛直方向に延びる柱主筋３２と、コンクリート体３１に埋設されて柱主筋３２に巻かれたフープ筋３３と、を備える。柱部３０の壁部２０の壁厚方向の幅（柱幅）は、壁部２０の壁厚と同一となっている。また、柱部３０の柱せい（正面視での見付け幅）は、壁部２０および柱部３０を含む耐力壁１０の全長（壁全長）の０．１倍～０．３倍程度とする。
壁部２０のコンクリート体２１および柱部３０のコンクリート体３１は、鋼繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成されている。鋼繊維は、両端にフック加工を施したものであり、鋼繊維の直径は０．１ｍｍ～０．６ｍｍ程度、鋼繊維長さは２０ｍｍ～５０ｍｍ程度が好ましい。
Fig. 3 is a front view of the bearing wall 10. Fig. 4 is a cross-sectional view taken along line B-B of the bearing wall 10 in Fig. 3. Fig. 5 is a cross-sectional view taken along line CC and line DD of the bearing wall 10 in Fig. 3.
The wall portion 20 comprises a concrete body 21 formed of fiber-reinforced concrete mixed with fibers, vertical reinforcement 22 embedded in the concrete body 21 and extending vertically, and horizontal reinforcement 23 embedded in the concrete body 21 and extending horizontally.
The column portion 30 comprises a concrete body 31 formed of fiber-reinforced concrete mixed with fibers, column main reinforcements 32 embedded in the concrete body 31 and extending vertically, and hoop reinforcements 33 embedded in the concrete body 31 and wrapped around the column main reinforcements 32. The width of the column portion 30 in the wall thickness direction of the wall portion 20 (column width) is the same as the wall thickness of the wall portion 20. The column depth (visible width when viewed from the front) of the column portion 30 is approximately 0.1 to 0.3 times the total length of the bearing wall 10 including the wall portion 20 and the column portion 30 (total wall length).
The concrete bodies 21 of the wall sections 20 and the concrete bodies 31 of the column sections 30 are made of fiber-reinforced concrete in which steel fibers are mixed in at 0.3% to 1.5% by volume of the concrete. The steel fibers are hooked on both ends, and the diameter of the steel fibers is preferably about 0.1 mm to 0.6 mm, and the length of the steel fibers is preferably about 20 mm to 50 mm.
耐力壁１０Ａは、耐力壁１０の上に複数層に亘って配置され、壁部２０のコンクリート体２１および柱部３０のコンクリート体３１が、繊維が混入されていないコンクリートで形成されている点が、耐力壁１０と異なり、その他の構成は耐力壁１０と同様である。
上下に位置する耐力壁１０、１０Ａの縦筋２２同士および柱主筋３２同士は、互いに接合されている。
The shear wall 10A is arranged in multiple layers on top of the shear wall 10, and differs from the shear wall 10 in that the concrete body 21 of the wall portion 20 and the concrete body 31 of the column portion 30 are formed from concrete that does not contain fibers, but the rest of the configuration is the same as that of the shear wall 10.
The vertical reinforcements 22 and the column main reinforcements 32 of the upper and lower bearing walls 10, 10A are joined to each other.
〔加力試験〕
以下、上述の耐力壁を模した４つの試験体（Ｎｏ．１～Ｎｏ．４）を製作し、水平力を加える加力試験を行うことで、ＳＦＲＣ（鋼繊維を混入した鉄筋コンクリート）の補強効果を検証した。
図６は、Ｎｏ．１～Ｎｏ．３試験体の構造を示す正面図、横断面図、および縦断面図である。図７は、図６の試験体の壁部および柱部の縦断面の拡大図である。図８は、図６の試験体の壁部および柱部の横断面の拡大図である。なお、Ｎｏ．４試験体は、壁部の横筋および縦筋の鉄筋量が、図６～図８のＮｏ．１～Ｎｏ．３試験体の２倍となっている。
試験体は、建物の下層部を想定し、実際の約１／３～１／４程度の大きさとした。また、各試験体を、壁のせん断破壊が壁脚部の曲げ降伏よりも先行するように製作した。具体的には、各試験体の壁厚を１８０ｍｍ、壁内法長さを１２００ｍｍ、柱幅を壁厚と同じ１８０ｍｍ、柱せいを５００ｍｍとした。
[Loading test]
Below, four test specimens (No. 1 to No. 4) that mimicked the above-mentioned shear walls were fabricated, and a loading test was conducted to apply horizontal force to verify the reinforcing effect of SFRC (steel fiber reinforced concrete).
Figure 6 shows the front view, cross section, and longitudinal section of the structure of specimens No. 1 to No. 3. Figure 7 is an enlarged view of the longitudinal section of the wall and column of the specimen in Figure 6. Figure 8 is an enlarged view of the cross section of the wall and column of the specimen in Figure 6. Note that specimen No. 4 had twice the amount of horizontal and vertical reinforcement in the wall compared to specimens No. 1 to No. 3 in Figures 6 to 8.
The test specimens were designed to simulate the lower floors of a building, and were approximately 1/3 to 1/4 the size of the actual building. Each specimen was also constructed so that shear failure of the wall preceded flexural yielding of the wall base. Specifically, the wall thickness of each specimen was 180 mm, the wall internal length was 1200 mm, the column width was the same as the wall thickness, 180 mm, and the column depth was 500 mm.
Ｎｏ．１～Ｎｏ．４試験体の構成を以下の表に示す。
表に示すように、壁部および柱部のコンクリート体を形成するコンクリートは、Ｎｏ．１試験体が普通コンクリート、Ｎｏ．２～Ｎｏ．４試験体が、鋼繊維を混入した繊維補強コンクリート（ＳＦＲＣ）とした。コンクリートの目標強度は、６０Ｎ／ｍｍ２とした。繊維混入量は、Ｎｏ．２、Ｎｏ．４試験体がコンクリート体積の０．５％、Ｎｏ．３試験体がコンクリート体積の１．０％とした。
なお、コンクリート中に混入する繊維は、径０．５５ｍｍ、長さ３５ｍｍ、アスペクト比６５、比重７．８５の鋼繊維とした。この鋼繊維は、両端を折り曲げたフック加工を施したものであり、直径が０．５５ｍｍ、長さが３５ｍｍである。
As shown in the table, the concrete forming the wall and column sections was ordinary concrete for specimen No. 1, and fiber-reinforced concrete (SFRC) containing steel fibers for specimens No. 2 to No. 4. The target strength of the concrete was 60 N/ mm2 . The amount of fiber mixed in was 0.5% of the concrete volume for specimens No. 2 and No. 4, and 1.0% of the concrete volume for specimen No. 3.
The fibers mixed into the concrete were steel fibers with a diameter of 0.55 mm, a length of 35 mm, an aspect ratio of 65, and a specific gravity of 7.85. These steel fibers had both ends bent into hooks, and were 0.55 mm in diameter and 35 mm in length.
各試験体の柱主筋は、せん断破壊が先行するように、１２－Ｄ１９（ＳＤ４９０）で鉄筋比ｐｇ＝３．８３％とした。
壁部の縦筋および横筋は、Ｎｏ．１～Ｎｏ．３試験体が、２－Ｄ６＠１２０（ＳＤ３４５）で鉄筋比ｐｓ＝０．３０％とし、Ｎｏ．４試験体が、２－Ｄ６＠６０（ＳＤ３４５）で鉄筋比ｐｓ＝０．５９％とし、Ｎｏ．３試験体とＮｏ．４試験体とが同等のせん断耐力となることを狙った。
The main column reinforcement of each specimen was 12-D19 (SD490) with a reinforcement ratio pg = 3.83% so that shear failure would occur first.
The vertical and horizontal reinforcement in the wall sections of specimens No. 1 to No. 3 were 2-D6@120 (SD345) with a reinforcement ratio of ps = 0.30%, while specimen No. 4 was 2-D6@60 (SD345) with a reinforcement ratio of ps = 0.59%, aiming for specimens No. 3 and No. 4 to have equivalent shear strength.
以上の試験体に対して、図９に示す加力装置で加力した。具体的には、加力装置により、試験体に加える軸力を保持しつつ、試験体の上部スタブに変位制御点を設置し、左右から水平荷重を繰り返し載荷によって与えた。軸力は、柱断面のみの軸力比ηが０．１５とした。この軸力比ηは、以下の式で求めた。
η＝Ｎ／（２・Ｂｃ・Ｄｃ・σＢ）
ここで、Ｎは軸力（柱２本分）、Ｂｃは柱幅（＝壁厚１８０ｍｍ）、Ｄｃは柱せい（＝５００ｍｍ）、σＢはコンクリート圧縮強度（Ｎ／ｍｍ２）である。
The above specimens were subjected to loading using the loading device shown in Figure 9. Specifically, while maintaining the axial force applied to the specimens using the loading device, displacement control points were installed on the upper stubs of the specimens, and horizontal loads were repeatedly applied from the left and right. The axial force ratio η of the column cross section alone was set to 0.15. This axial force ratio η was calculated using the following formula.
η=N/(2・Bc・Dc・σB)
Here, N is the axial force (for two columns), Bc is the column width (=wall thickness 180 mm), Dc is the column depth (=500 mm), and σB is the concrete compressive strength (N/mm 2 ).
図１０は、加力試験の結果（水平荷重Ｑと水平変位量δとの関係）を示す図である。
図１０より、最大水平荷重ＱＭＡＸは、Ｎ０．２試験体がＮｏ．１試験体の１．１１倍、Ｎｏ．３試験体がＮｏ．１試験体の１．１８倍、Ｎｏ．４試験体がＮｏ．１試験体の１．１７倍となることが判る。また、Ｎｏ．２～Ｎｏ．４試験体では、Ｎｏ．１試験体と比べて、水平荷重Ｑが最大に達した後の急減な低下を防止でき、変形性能が向上した。よって、普通コンクリートでは、ひび割れが発生した際、引張応力を負担することが困難であるため，ひび割れが大きく進展するが、繊維補強コンクリートは，ひび割れが発生した際、ひび割れを架ける繊維が引張応力を負担することで、ひび割れの拡幅を防止して、同一の荷重または同一の変形時にひび割れ幅が小さくなることが判る。
また、図１０より、Ｎｏ．３試験体は、Ｎｏ．４試験体よりも荷重の低下が緩やかであり、同等のせん断耐力となる場合でも、鋼繊維量が多い方が、変形性能が大きいことが判る。
FIG. 10 is a diagram showing the results of the load test (the relationship between the horizontal load Q and the horizontal displacement δ).
Figure 10 shows that the maximum horizontal load QMAX for specimen No. 2 was 1.11 times that of specimen No. 1, specimen No. 3 was 1.18 times that of specimen No. 1, and specimen No. 4 was 1.17 times that of specimen No. 1. Furthermore, specimens No. 2 to No. 4 were able to prevent a sudden drop in Qmax after reaching its maximum, compared to specimen No. 1, thereby improving their deformation performance. Therefore, when cracks occur in ordinary concrete, they have difficulty bearing the tensile stress, causing the cracks to grow significantly. However, when cracks occur in fiber-reinforced concrete, the fibers bridging the cracks bear the tensile stress, preventing the cracks from widening. This results in smaller crack widths for the same load or deformation.
Furthermore, Figure 10 shows that the load decrease in Specimen No. 3 is more gradual than in Specimen No. 4, and that even when the shear strength is the same, a larger amount of steel fiber results in greater deformation performance.
よって、図１０より、柱幅が壁厚と同一でかつコンクリート体積に対して鋼繊維を０.５％または１.０％混入した繊維補強コンクリートで形成した耐力壁は、鋼繊維量を混入していない普通コンクリートで形成した耐力壁に比べて、ひび割れ幅が小さくなり、限界変形角（靭性能）が向上し、耐力と変形性能に優れていることが判る。
また、今回の加力試験より、コンクリート体積に対して鋼繊維を０.５％または１.０％混入することで、耐力および変形性能を改善できることが確認できた。
本発明の耐力壁では、壁部および柱部のコンクリート体は、繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成することが好ましい。今回の加力試験の試験体の製作については、鋼繊維量を、建設現場で普通コンクリートに混入する量を容易に管理できかつ攪拌可能な量として、０．５％または１．０％とした。
また、本発明の耐力壁では、柱部の幅を壁部の壁厚の１倍以上２倍未満とすることが好ましい。今回の加力試験の試験体の製作については、施工性を考慮して、柱部の幅を壁厚と同一とした。
また、本発明の耐力壁を備えた連層耐震壁では、図２に示すように、繊維が混入された耐力壁を１層以上配置し、これら耐力壁の上に繊維が混入されていない耐力壁を配置する。このように、繊維が混入された耐力壁を限定的に配置することで、繊維が混入された耐力壁を建物の全ての階に設けなくても、連層耐震壁の構造性能を高めることができる。
Therefore, from Figure 10, it can be seen that a bearing wall made of fiber-reinforced concrete with a column width equal to the wall thickness and containing 0.5% or 1.0% steel fiber relative to the concrete volume has smaller crack widths and improved limit deformation angle (toughness), and is superior in strength and deformation performance, compared to a bearing wall made of ordinary concrete without steel fiber mixed in.
Furthermore, this loading test confirmed that the strength and deformation performance could be improved by mixing 0.5% or 1.0% steel fiber into the concrete volume.
In the case of the shear wall of the present invention, the concrete body of the wall and columns is preferably made of fiber-reinforced concrete with fibers mixed in at 0.3% to 1.5% by volume of concrete. In the fabrication of the specimens for the loading test, the amount of steel fiber was set to 0.5% or 1.0%, which is an amount that can be easily controlled and mixed into ordinary concrete at the construction site.
Furthermore, in the shear wall of the present invention, it is preferable that the width of the column portion is at least 1 time but less than 2 times the wall thickness of the wall portion. In the fabrication of the specimen for this loading test, the width of the column portion was set to be the same as the wall thickness, taking into consideration ease of construction.
Furthermore, in the multi-story shear wall equipped with the shear walls of the present invention, one or more layers of shear walls containing fiber are arranged, and shear walls without fiber are arranged above these shear walls, as shown in Figure 2. In this way, by arranging the shear walls containing fiber only in a limited manner, the structural performance of the multi-story shear wall can be improved without having to install shear walls containing fiber on every floor of the building.
本実施形態によれば、以下のような効果がある。
（１）壁部２０および柱部３０を含んで耐力壁１０を構成し、これら壁部２０および柱部３０を、鋼繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成した。よって、鋼繊維がせん断補強筋と同等以上の補強効果を発揮するため、壁部や柱部にせん断補強筋を過密に配筋する必要がない。
その結果、柱部３０を大断面化することなく、柱部３０の幅を壁部２０の壁厚さと同一としても、耐力と変形性能に優れた耐力壁１０を実現できる。
また、普通コンクリートではなく鋼繊維を混入した繊維補強コンクリートを用いて、壁部２０および柱部３０のコンクリート体２１、３１を構築したので、施工性が良い。
また、耐力壁１０、１０Ａを備えた連層耐震壁では、耐力壁１０が設けられた下層部では，コンクリートに鋼繊維を混入する分のコストの増加が発生するが、鋼繊維を混入した耐力壁１０の変形性能が向上するため、建物１の変形性能が向上し、周辺架構の物量を削減できる。
According to this embodiment, the following effects are obtained.
(1) The bearing wall 10 is made up of wall sections 20 and column sections 30, and these wall sections 20 and column sections 30 are made of fiber-reinforced concrete with steel fibers mixed in at 0.3% to 1.5% by volume of concrete. Therefore, since the steel fibers have a reinforcing effect equal to or greater than that of shear reinforcement, there is no need to densely arrange shear reinforcement in the wall sections or column sections.
As a result, even if the width of the column portion 30 is the same as the wall thickness of the wall portion 20 without increasing the cross section of the column portion 30, a bearing wall 10 with excellent strength and deformation performance can be realized.
Furthermore, since the concrete bodies 21, 31 of the wall section 20 and the column section 30 are constructed using fiber-reinforced concrete containing steel fibers instead of ordinary concrete, workability is good.
Furthermore, in a multi-story earthquake-resistant wall equipped with shear walls 10 and 10A, the cost of mixing steel fibers into the concrete in the lower story where the shear wall 10 is installed increases, but the deformation performance of the shear wall 10 with the steel fibers mixed in is improved, which improves the deformation performance of the building 1 and allows for a reduction in the amount of material in the surrounding structure.
（２）繊維補強コンクリートに混入する繊維として、両端部が折り曲げられた鋼繊維を用いたので、鋼繊維の折り曲げ部でコンクリートと鋼繊維との間の付着性能が高まる。
また、鋼繊維の熱膨張係数は、コンクリートとほぼ等しいので、温度変化により生じる内部応力を低減可能であり、鋼繊維とコンクリートの一体性を確保することができる。
（３）繊維補強コンクリートで形成された耐力壁１０の上側に、繊維が混入されていないコンクリートで形成された別の耐力壁１０Ａを設けるとともに、双方の壁の縦筋２２および柱主筋３２同士を接合した。よって、建物１の全ての階に繊維補強コンクリートで形成された耐力壁１０を設けなくても、せん断耐力および変形性能に優れた建物１を実現できる。
(2) Steel fibers with bent ends are used as the fibers mixed into the fiber-reinforced concrete, so the adhesion between the concrete and the steel fibers is improved at the bent portions of the steel fibers.
Furthermore, since the thermal expansion coefficient of steel fibers is approximately equal to that of concrete, it is possible to reduce internal stress caused by temperature changes, and to ensure the integrity of the steel fibers and concrete.
(3) A bearing wall 10A made of concrete without fibers is provided above the bearing wall 10 made of fiber-reinforced concrete, and the vertical reinforcement 22 and main column reinforcement 32 of both walls are joined together. Therefore, even if bearing walls 10 made of fiber-reinforced concrete are not provided on all floors of the building 1, a building 1 with excellent shear strength and deformation performance can be realized.
なお、本発明は前記実施形態に限定されるものではなく、本発明の目的を達成できる範囲での変形、改良等は本発明に含まれるものである。 The present invention is not limited to the above-described embodiments, and any modifications, improvements, etc. that achieve the objectives of the present invention are included in the present invention.
１…建物（構造物） ２…柱 ３…梁
１０…耐力壁 １０Ａ…別の耐力壁
２０…壁部 ２１…コンクリート体 ２２…縦筋 ２３…横筋
３０…柱部 ３１…コンクリート体 ３２…柱主筋 ３３…フープ筋
REFERENCE SIGNS LIST 1... Building (structure) 2... Column 3... Beam 10... Bearing wall 10A... Another bearing wall 20... Wall section 21... Concrete body 22... Vertical reinforcement 23... Horizontal reinforcement 30... Column section 31... Concrete body 32... Main column reinforcement 33... Hoop reinforcement
Claims (2)
鉄筋コンクリート造の壁部と、
前記壁部の水平方向端部に設けられる鉄筋コンクリート造の柱部と、を備え、
前記壁部および前記柱部のコンクリート体は、両端部が折り曲げられた鋼繊維がコンクリート体積に対して０.３％以上１．５％以下混入された繊維補強コンクリートで形成され、
前記柱部の幅は、前記壁部の壁厚の１倍以上２倍未満であることを特徴とする耐力壁。 A reinforced concrete bearing wall,
Reinforced concrete walls and
and a reinforced concrete column portion provided at the horizontal end of the wall portion,
The concrete bodies of the wall and column portions are formed of fiber-reinforced concrete in which steel fibers with bent ends are mixed in an amount of 0.3% to 1.5% by volume of concrete,
A shear wall characterized in that the width of the column portion is greater than or equal to one time but less than two times the wall thickness of the wall portion.
前記耐力壁の上側または下側には、別の耐力壁が配置され、
前記別の耐力壁は、繊維が混入されていない鉄筋コンクリート造の壁部と、前記壁部の水平方向端部に設けられる、繊維が混入されていない鉄筋コンクリート造の柱部と、を備え、
前記耐力壁の壁部の縦筋は、前記別の耐力壁の壁部の縦筋に接合され、
前記耐力壁の柱部の柱主筋は、前記別の耐力壁の柱部の柱主筋に接合されていることを特徴とする構造物。 A structure comprising the reinforced concrete bearing wall according to claim 1 ,
Another bearing wall is arranged above or below the bearing wall,
The other bearing wall comprises a wall section made of reinforced concrete not mixed with fibers, and a column section made of reinforced concrete not mixed with fibers and provided at a horizontal end of the wall section,
The vertical reinforcement of the wall portion of the bearing wall is connected to the vertical reinforcement of the wall portion of the other bearing wall,
A structure characterized in that the main reinforcement of the column of the bearing wall is connected to the main reinforcement of the column of the other bearing wall.
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