JP4346259B2

JP4346259B2 - Reinforced concrete seismic column

Info

Publication number: JP4346259B2
Application number: JP2001156469A
Authority: JP
Inventors: 雅敬木下; 浩和家村; 良和高橋
Original assignee: Nippon Steel Engineering Co Ltd
Current assignee: Nippon Steel Engineering Co Ltd
Priority date: 2001-05-25
Filing date: 2001-05-25
Publication date: 2009-10-21
Anticipated expiration: 2021-05-25
Also published as: JP2002349011A

Description

【０００１】
【発明の属する技術分野】
本発明は、耐震性に優れたＲＣ（鉄筋コンクリート）製柱状部材の構造に関する。
【０００２】
【従来の技術】
高い耐震性を持つ柱状部材としては、従来、例えばＰＣ（プレストレストコンクリート）製の柱状部材が知られており、これはプレストレス（予加応力）を与えて柱状物の実質的な耐力および剛性を上げておくことで、残留変位を小さくしようとするものである。しかし、ＰＣ製の柱状部材は、プレストレスによりコンクリートに常時、外力を打ち消す方向の応力が負荷されているため、コンクリートの圧壊によって定義される耐力相当の変形が、通常のＲＣ製の柱状部材よりも小さくなり、変形性能が減少するという欠点を有する。
【０００３】
一方、従来、各種強度の鉄筋を混用したＲＣ製の柱状部材も知られており、これは異なった降伏強度を有する鉄筋を導入し、それらの鉄筋が順次降伏することにより荷重−変形関係に二次剛性を付与することを目的としている。ただし、大変形時には、全ての鉄筋が降伏するため、弾性的な復元力を確保することができず、残留変形の低減も困難である。
【０００４】
一般の耐震設計では、比較的頻度の高いレベルＩの地震動に対しては強度設計を行い、頻度は低いが強烈なレベルＩＩの地震動に対しては部材の塑性領域を含め変形性能を評価する保有水平耐力照査を行う、二段階設計を行っているが、例えば橋脚については、大地震後も比較的早期に修復可能なものとするために、残留変形が橋脚高さの１／１００であることをも同時に要求している。
【０００５】
すなわち、耐震性に富む橋脚とは、レベルＩの地震動に対しては高い耐力を備え、レベルＩＩの地震動に対しては大きな靭性と小さな残留変形という性能を兼ね備えた橋脚といえるが、特にレベルＩＩの地震動における大きな靭性と小さな残留変形との要求項目は相反する要求であり、従来のＲＣ橋脚では実現することが極めて困難であった。
【０００６】
【発明が解決しようとする課題】
そこで、本発明は、柱状部材の大変形時に弾性的に対応可能に強化し、塑性変形域における靭性の強化および残留変位の低減を目的とする。
【０００７】
【課題を解決するための手段】
前記課題を解決するために、本発明は次のように構成する。
【０００８】
請求項１に記載の発明は、立設されたコンクリート躯体と、前記コンクリート躯体の長手方向に延びて埋設された構造用主鉄筋と、前記構造用主鉄筋よりも高強度を有し主鉄筋の内側にほぼ平行に延びて埋設された芯材とを備える鉄筋コンクリート製柱状部材において、前記芯材を鞘管等のアンボンド層により周囲のコンクリート躯体と隔てて配設すると共に、当該芯材の上下両端部または下端部をコンクリート躯体に当接し、この芯材の当接端部と前記アンボンド層端部に配設の定着部材との間を可縮性部材配設区間とし、当該区間に配設した可縮性部材の圧縮により芯材一端部側へコンクリート躯体が相対変位可能とし、柱状部材の大変形時における可縮性部材の圧縮代解消により、芯材の弾性的作用が前記定着部材を介してコンクリート躯体に伝達されて外力に抵抗することを特徴とする。
【０００９】
請求項２に記載の発明は、請求項１に記載の発明において、前記可縮性部材がゴムまたはコイルばねまたは皿ばね等からなることを特徴とする。
【００１０】
請求項３に記載の発明は、請求項１または２に記載の発明において、前記可縮性部材の圧縮代が前記コンクリート躯体および主鉄筋の降伏点変位を考慮して設定されることを特徴とする。
【００１１】
請求項４に記載の発明は、請求項１〜３の何れかに記載の発明において、前記芯材の上下両端部または下端部を、コンクリート躯体に埋設の可動定着部材ユニットに定着し、この可動定着部材ユニットは、所定の間隔を離して配設した上下の定着板と、両板の間に挟まれて固着されたケーシングと、定着板の開口を通してケーシング内に進入し、端部が定着板に当接し、この端部に押圧プレートを固着した芯材端部と、押圧プレートと定着板との間の可縮性部材配設区間Ｓに配設した可縮性部材とから構成されていることを特徴とする。
【００１２】
【作用】
本発明によると、柱状部材が引張外力を受けた場合、まずコンクリートおよび主鉄筋が外力を負担し変位する。これと同時に芯材下端部の可縮性部材が圧縮される。芯材は可縮性部材が圧縮されつつある間は引張力を負担しないが、例えば、主鉄筋の引張降伏点変位を越える塑性変位区間に入ると、可縮性部材の圧縮代はなくなり、高強度の芯材が定着部材を介してコンクリート躯体に負担メンバーとして加わる。こうして、柱状部材の塑性域において芯材の作用が付加され、芯材が弾性的に抵抗するため、柱状部材の靭性は増大し、弾性的な復元力の付与により残留変位が小さくなる。反対に、柱状部材が圧縮外力を受けた場合は、芯材の下端がコンクリート躯体と当接していることで、当該芯材が抵抗し、本来圧縮に強いコンクリートの圧縮強度が芯材によって一層補強される。
【００１３】
また、芯材の上下両端部に可縮性部材を配置した場合には、柱状部材が引張力、圧縮力のいずれの外力を受けた場合にも、外力に対する芯材の同様の作用が得られる。
【００１４】
【発明の実施の形態】
〔第１実施形態〕
本発明の第１実施形態について図１〜図１１を参照して説明する。
【００１５】
図１は本実施形態の鉄筋コンクリート（ＲＣ）製橋脚の構造を模式的に示す構造図である。図２、図３と図４はそれぞれ図１のＡ−Ａ断面図、Ｂ−Ｂ断面図、C−C断面図である。図５〜図８は要部の構造についての説明図である。また、図９〜図１１は負荷時の特性を示す説明図である。
【００１６】
図１〜図４に示すように、柱状部材の一例として示す、鉄筋コンクリート（ＲＣ）製橋脚１は、従来の通常のＲＣ製橋脚と同様に、コンクリート躯体１ａと、そのコンクリート躯体１ａの表面付近にその長手方向に延びて埋設された構造用主鉄筋１ｂと、長手方向に直交して主鉄筋１ｂを囲むように埋設された横拘束鉄筋１ｃを主要素として構成され、これに加えて鞘管３と共に、主鉄筋１ｂの内側に基礎部分１ｄから橋脚１の中間部分まで延びて配置された複数（ここでは４本）の高強度の芯材２が付加されて構成されている。
【００１７】
芯材２は、例えば高弾性鋼棒で構成されると共に、図１に示すように、前記の鞘管３はアンボンド層を形成する部材の一例として示され、芯材２の外部にその略全長に亘って嵌合され、この鞘管３を介して、芯材２が周囲のコンクリート躯体１ａから隔てられて配置されることで、アンボンド区間Ｄが設けられている。芯材２と鞘管３との隙間は芯材２の座屈防止のために小さく抑えられている。
【００１８】
芯材２の上端部２ａは、橋脚１の中間部分の内部において、通常の構造の定着部４により、コンクリート躯体１ａに定着されているが、芯材２の下端部２ｂは、コンクリート躯体１ａに埋設された可動定着部材ユニット５により、後述の可縮性部材７の圧縮を介して、当該芯材２を伸長する方向の外力を負担するように構成されている。
【００１９】
可動定着部材ユニット５は、詳細を図５に示すように、所定の間隔を離して平行配設した上下の定着板６ａ、６ｂと、両定着板６ａ、６ｂの間に挟まれ両端が閉塞されるようにして両板に固着された筒状のケーシング１０と、上部定着板６ａの開口１１を通してケーシング１０内に進入した芯材２の下端部２ｂと、この下端部２ｂに螺着したナット２ｅからなる押圧プレート２ｃと、ケーシング１０内において、押圧プレート２ｃと上部定着板６ａの間の可縮性部材配設区間Ｓに配設した可縮性部材の一例として示す、コの字状縦断面を有するゴム部材７から構成されている。
【００２０】
前述の構成において、橋脚１が引張り外力を受けた場合に、図５（ａ）、（ｂ）に示すように、芯材２はゴム部材７の圧縮により上方への変位が許容されている。ゴム部材７の圧縮代Ｓ₁の設定は、例えば橋脚１が引張り外力を受けて主鉄筋１ｂが降伏し、塑性域に入るときの変位量よりも若干小さい値に圧縮代Ｓ₁を設定するなど調整可能に設定する方法がとられる。これにより、主鉄筋１ｂが塑性変形域（橋脚１が大変形領域）に入っても、芯材２が引張り外力に対して弾性的に挙動する開始時期を調整することが可能となる。
【００２１】
この弾性挙動を示すようにするため、芯材２には主鉄筋１ｂよりも高強度の材料、例えば既述の高弾性鋼棒や、高強度鉄筋、アラミド繊維等の新素材が用いられている。また、芯材２の全長の設定は、橋脚１の大変形領域において、例えば芯材２が降伏せずに弾性的伸び量にて振舞うことができるように設定する。
【００２２】
このように、橋脚１の耐震機能が効果的に発揮されるためには、高強度の芯材２が橋脚１の大変形時においても弾性挙動しなければならない。そのため前記のように、芯材２には構造用主鉄筋１ｂよりも高強度のものを用い、かつこの芯材２は構造用主鉄筋１ｂよりも変位の少ない内部に配置し、芯材２とコンクリート躯体１ａとが付着しないアンボンド区間Ｄを設けることにより、図９（ｂ）に示すように、芯材２の変位（歪み）はその全長に亘って均一化される。図９（ａ）は、比較のために芯材２が配設されていない通常のＲＣ製橋脚の場合を示す。
【００２３】
なお、可動定着部材ユニット５の可縮性部材配設区間Ｓに配設する可縮性部材としては、前述のゴム部材７に代えて、図６、図８にそれぞれ示すコイルばね８、皿ばね９を配設させる構成をとっても勿論よい。図６、図８（ａ）は、ばね８，９の取り付け状態を示し、図６、図８（ｂ）は圧縮された状態を示す。
【００２４】
このような構成により、図１０（ａ）に示すような通常のＲＣ製橋脚の変位−復元力関係に、同図（ｂ）に示すような芯材２の弾性的な変位−復元力関係を付加することができるので、同図（ｃ）に示すように、ＲＣ製橋脚１の変位−復元力関係の塑性域において芯材２の復元力（二次剛性）を付与することができ、これにより、ＲＣ製橋脚１の塑性域における靭性の増大と残留変形の低減が得られる。
【００２５】
図１１（ａ）〜（ｃ）は、残留変位の低減の原理を示す。すなわち、通常の鉄筋コンクリート構造を持つＲＣ製橋脚のみでは、図１０（ａ）に示すように塑性域における剛性が極めて低いことから、図１１（ａ）に示すように大地震後の残留変位が大きなものとなる。しかし、図１０（ｂ）および図１１（ｂ）に示すような高強度の芯材２をアンボンド区間Ｄおよびゴム部材７の圧縮代（不感帯）Ｓ₁を設けて付加することで、図１１（ｃ）に示すように、変位がゴム部材７の圧縮代Ｓ₁より小のときはＲＣ製橋脚のみの場合と同じ履歴を呈し、変位が大きくて圧縮代Ｓ₁がなくなると芯材２の弾性的な復元力が付与されて、ＲＣ製橋脚のみの場合よりも残留変位が小さくなる。
【００２６】
［第２実施形態］
本発明の第２実施形態について図１１、図１２を参照して説明する。図１２は本実施形態の鉄筋コンクリート（ＲＣ）製橋脚１ｅ（柱状部材）の構造を模式的に示す構造図である。
【００２７】
本実施形態は、芯材２の上下両端部２ａ，２ｂにゴム部材７等の可縮性部材を設けている点が、前記第１実施形態（下端部２ｂのみ）と相違する。その構成は同じであるので、同一要素に同一符号を付して重複説明を省略する。
【００２８】
図１２に示すように、芯材２の上下両端部２ａ，２ｂは共にゴム部材７を介して、可動定着部材ユニット５の一方の定着板６ａに設置されている。したがって、芯材２はゴム部材７の圧縮により上方への変位と共に、下方への変位が許容され、橋脚の引張、圧縮いずれの大変形領域においても、芯材２が弾性的に挙動できるように調整可能となる。
【００２９】
また、逆に芯材２の上下両端部部２ａ，２ｂにおける定着部５のゴム部材７を廃止した場合には、図１１（ｄ）に示すように橋脚に作用する外力に対して直ちに芯材２が抵抗し、図１１（ｅ）に示すように残留変位は小さくなるが、同変位時におけるエネルギー吸収量はＲＣ製橋脚のみの場合と同じとなる。
【００３０】
なお、前記の各実施形態ではＲＣ製橋脚１について説明したが、本発明はＲＣ製橋脚１に限定されるものではなく、その他各種のＲＣ製柱状部材に適用できることは勿論である。
【００３１】
【発明の効果】
以上の説明から明らかなように、本発明によれば、柱状部材の大変形時で主鉄筋が降伏して塑性域に入ると、高強度の芯材が外力に対して弾性的に抵抗するため、柱状部材の靭性は増大し、弾性的な復元力の付与により残留変位が小さくなって、靭性は大、残留変位は小という相反する要求に対応することが可能となり、さらに、柱状部材が圧縮外力を受けた場合は、芯材の下端がコンクリート躯体と当接していることで、当該芯材が抵抗し、本来圧縮に強いコンクリートの圧縮強度が芯材によって一層補強される効果がある。
【図面の簡単な説明】
【図１】本発明の第１実施形態の鉄筋コンクリート（ＲＣ）製橋脚の構造を模式的に示す構造図である。
【図２】図１のＡ−Ａ断面図である。
【図３】図１のＢ−Ｂ断面図である。
【図４】図１のＣ−Ｃ断面図である。
【図５】（ａ）、（ｂ）は、第１実施形態の要部の構造を示す断面説明図である。
【図６】（ａ）、（ｂ）は、第１実施形態の要部の構造変更例を示す説明図である。
【図７】（ａ）は、図５（ａ）のＥ−Ｅ線の断面図、（ｂ）は、図６（ａ）のＦ−Ｆ線の断面図である。
【図８】第１実施形態の要部の構造変更における他の例を示す説明図である。
【図９】第１実施形態における芯材の歪みを通常の構造の場合と比較して示す説明図である。
【図１０】第１実施形態の静的特性を示す説明図である。
【図１１】第１実施形態の残留変位を示す説明図である。
【図１２】本発明の第２実施形態の鉄筋コンクリート（ＲＣ）製橋脚の構造を模式的に示す構造図である。
【符号の説明】
１，１ｅ鉄筋コンクリート（ＲＣ）製橋脚（柱状部材）
１ａコンクリート躯体
１ｂ構造用主鉄筋
１ｃ横拘束鉄筋
１ｄ基礎部分
２芯材
２ａ上端部
２ｂ下端部
２ｃ押圧プレート
３鞘管
４定着部
５可動定着部材ユニット
６ａ，６ｂ定着板
７ゴム部材（可縮性部材）
８コイルばね（可縮性部材）
９皿ばね（可縮性部材）
１０ケーシング
１１開口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of an RC (steel reinforced) columnar member having excellent earthquake resistance.
[0002]
[Prior art]
As a columnar member having high earthquake resistance, for example, a columnar member made of, for example, PC (prestressed concrete) is known, and this gives prestress (pre-stressed stress) to reduce the substantial strength and rigidity of the columnar object. By raising it, it is intended to reduce the residual displacement. However, since the PC columnar member is always subjected to stress in the direction that cancels the external force due to pre-stress, the deformation equivalent to the proof stress defined by the collapse of the concrete is more than that of the normal RC columnar member. And the deformation performance is reduced.
[0003]
On the other hand, RC columnar members that use reinforcing bars of various strengths are also known in the past, and this introduces reinforcing bars having different yield strengths, and these reinforcing bars yield in succession so that a load-deformation relationship is established. The purpose is to provide the next rigidity. However, since all the reinforcing bars yield at the time of large deformation, it is not possible to ensure an elastic restoring force, and it is difficult to reduce residual deformation.
[0004]
In general seismic design, strength design is performed for relatively frequent level I ground motions, and deformation performance is evaluated for infrequent but intense level II ground motions including the plastic region of members. We are conducting a two-stage design that conducts a horizontal strength check, but for piers, for example, residual deformation should be 1/100 of the pier height so that it can be repaired relatively early after a major earthquake. At the same time.
[0005]
In other words, a pier with high earthquake resistance can be said to be a pier that has high strength against Level I ground motion and has both high toughness and small residual deformation performance against Level II ground motion. The requirements of large toughness and small residual deformation in the ground motion are conflicting requirements, and it was extremely difficult to achieve with conventional RC piers.
[0006]
[Problems to be solved by the invention]
Therefore, the present invention aims to reinforce the columnar member so that it can elastically cope with large deformation, and to strengthen toughness and reduce residual displacement in the plastic deformation region.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows.
[0008]
The invention according to claim 1 is a concrete frame erected, a structural main reinforcing rod extending in the longitudinal direction of the concrete casing, and a strength higher than that of the structural main reinforcing bar. In a reinforced concrete columnar member provided with a core material extending substantially in parallel to the inside, the core material is disposed apart from the surrounding concrete frame by an unbond layer such as a sheath tube, and both upper and lower ends of the core material The lower end or the lower end is brought into contact with the concrete casing, and a space between the contact end of the core member and the fixing member provided at the end of the unbonded layer is defined as a retractable member disposition section, and disposed in the section. By compressing the compressible member, the concrete frame can be relatively displaced toward one end of the core material, and the elastic action of the core material is caused to pass through the fixing member by eliminating the compression allowance of the retractable member when the columnar member is largely deformed. Concree Is transmitted to the precursor, characterized in that the resistance to external force.
[0009]
The invention according to claim 2 is characterized in that, in the invention according to claim 1, the retractable member is made of rubber, a coil spring, a disc spring or the like.
[0010]
The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the compression allowance of the retractable member is set in consideration of the yield point displacement of the concrete frame and the main reinforcing bar. To do.
[0011]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the upper and lower end portions or the lower end portion of the core member is fixed to a movable fixing member unit embedded in a concrete frame, and this movable portion is fixed. The fixing member unit enters the casing through the upper and lower fixing plates arranged at a predetermined interval, the casing sandwiched and fixed between the two plates, and the opening of the fixing plate, and the end portion contacts the fixing plate. It is comprised from the core material edge part which contact | adhered and fixed the press plate to this edge part, and the retractable member arrange | positioned in the retractable member arrangement | positioning area S between a press plate and a fixing plate. Features.
[0012]
[Action]
According to the present invention, when the columnar member receives a tensile external force, first, the concrete and the main reinforcing bar bear the external force and are displaced. At the same time, the retractable member at the lower end of the core material is compressed. While the core material does not bear a tensile force while the compressible member is being compressed, for example, when the plastic displacement section exceeds the tensile yield point displacement of the main reinforcing bar, the compression allowance of the compressible member disappears and the high A strong core is added as a burden member to the concrete frame via the fixing member. In this way, the action of the core material is added in the plastic region of the columnar member, and the core material elastically resists, so the toughness of the columnar member increases and the residual displacement is reduced by applying an elastic restoring force. On the other hand, when the columnar member receives a compression external force, the lower end of the core material is in contact with the concrete casing, so that the core material resists, and the compressive strength of concrete that is inherently resistant to compression is further reinforced by the core material. Is done.
[0013]
Further, when the retractable members are arranged at the upper and lower end portions of the core material, the same action of the core material with respect to the external force can be obtained even when the columnar member receives either an external force of a tensile force or a compressive force. .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS.
[0015]
FIG. 1 is a structural diagram schematically showing the structure of a reinforced concrete (RC) pier according to this embodiment. 2, FIG. 3 and FIG. 4 are respectively a cross-sectional view taken along line AA, a cross-sectional view taken along a line BB, and a cross-sectional view taken along a line CC in FIG. 5-8 is explanatory drawing about the structure of the principal part. 9-11 is explanatory drawing which shows the characteristic at the time of load.
[0016]
As shown in FIGS. 1 to 4, a reinforced concrete (RC) pier 1 shown as an example of a columnar member is similar to a conventional normal RC pier in the vicinity of a concrete frame 1 a and the surface of the concrete frame 1 a. The structural main reinforcing bar 1b extending in the longitudinal direction and the laterally constrained reinforcing bar 1c embedded so as to surround the main reinforcing bar 1b perpendicularly to the longitudinal direction are constituted as main elements. In addition, the sheath tube 3 At the same time, a plurality of (four in this case) high-strength cores 2 arranged to extend from the base portion 1d to the middle portion of the pier 1 are added to the inside of the main reinforcing bar 1b.
[0017]
The core material 2 is composed of, for example, a high-elasticity steel rod, and as shown in FIG. 1, the sheath tube 3 is shown as an example of a member that forms an unbonded layer. The unbonded section D is provided by the core material 2 being spaced apart from the surrounding concrete housing 1a via the sheath tube 3 and being disposed. The gap between the core material 2 and the sheath tube 3 is kept small to prevent buckling of the core material 2.
[0018]
The upper end portion 2a of the core material 2 is fixed to the concrete housing 1a by the fixing portion 4 having a normal structure inside the intermediate portion of the pier 1, but the lower end portion 2b of the core material 2 is fixed to the concrete housing 1a. The embedded movable fixing member unit 5 is configured to bear an external force in a direction in which the core member 2 is extended through compression of a retractable member 7 described later.
[0019]
As shown in detail in FIG. 5, the movable fixing member unit 5 is sandwiched between upper and lower fixing plates 6a and 6b arranged in parallel at a predetermined interval and both fixing plates 6a and 6b, and both ends are closed. In this way, the cylindrical casing 10 fixed to both plates, the lower end 2b of the core member 2 that has entered the casing 10 through the opening 11 of the upper fixing plate 6a, and the nut 2e screwed to the lower end 2b. A U-shaped longitudinal section shown as an example of a retractable member disposed in a retractable member disposition section S between the press plate 2c and the upper fixing plate 6a in the casing 10 and the pressing plate 2c. It is comprised from the rubber member 7 which has.
[0020]
In the above-described configuration, when the pier 1 receives a tensile external force, the core member 2 is allowed to be displaced upward by the compression of the rubber member 7 as shown in FIGS. 5 (a) and 5 (b). The compression margin S ₁ of the rubber member 7 is set, for example, by setting the compression margin S ₁ to a value slightly smaller than the amount of displacement when the pier 1 receives a tensile external force and the main reinforcing bar 1b yields and enters the plastic region. A method of setting to be adjustable is taken. Thereby, even if the main reinforcing bar 1b enters the plastic deformation region (the pier 1 is a large deformation region), it is possible to adjust the start time when the core material 2 behaves elastically with respect to the tensile external force.
[0021]
In order to show this elastic behavior, the core material 2 is made of a material higher in strength than the main reinforcing bar 1b, for example, a new material such as the above-described high elastic steel bar, high strength reinforcing bar, aramid fiber or the like. . Further, the length of the core material 2 is set so that, for example, the core material 2 can behave with an elastic elongation amount without yielding in the large deformation region of the pier 1.
[0022]
Thus, in order for the seismic function of the pier 1 to be exhibited effectively, the high-strength core member 2 must behave elastically even when the pier 1 is largely deformed. Therefore, as described above, the core material 2 having a strength higher than that of the structural main reinforcing bar 1b is used, and the core material 2 is disposed inside the structural main reinforcing bar 1b with less displacement. By providing the unbond section D where the concrete housing 1a does not adhere, the displacement (distortion) of the core material 2 is made uniform over the entire length as shown in FIG. 9B. FIG. 9A shows a case of a normal RC pier in which the core material 2 is not disposed for comparison.
[0023]
As the retractable member disposed in the retractable member disposition section S of the movable fixing member unit 5, instead of the rubber member 7 described above, a coil spring 8 and a disc spring illustrated in FIGS. 6 and 8, respectively. Of course, a configuration in which 9 is disposed may be adopted. FIGS. 6 and 8A show the attached state of the springs 8 and 9, and FIGS. 6 and 8B show the compressed state.
[0024]
With such a configuration, the relationship between the displacement and restoring force of a normal RC bridge pier as shown in FIG. 10A is changed to the relationship between the elastic displacement and restoring force of the core member 2 as shown in FIG. Since it can be added, the restoring force (secondary rigidity) of the core material 2 can be imparted in the plastic region of the displacement-restoring force relationship of the RC pier 1 as shown in FIG. As a result, an increase in toughness and a reduction in residual deformation in the plastic region of the RC pier 1 can be obtained.
[0025]
11A to 11C show the principle of reducing the residual displacement. That is, only RC bridge piers having a normal reinforced concrete structure have extremely low rigidity in the plastic region as shown in FIG. 10 (a), so that the residual displacement after a large earthquake is large as shown in FIG. 11 (a). It will be a thing. However, by adding the high-strength core material 2 as shown in FIG. 10B and FIG. 11B with the unbonded section D and the compression allowance (dead zone) S ₁ of the rubber member 7 added, FIG. As shown in c), when the displacement is smaller than the compression allowance S ₁ of the rubber member 7, the same history as that of the RC bridge pier alone is exhibited, and when the displacement is large and the compression allowance S ₁ is lost, the elasticity of the core material 2 is exhibited. A residual restoring force is applied, and the residual displacement is smaller than in the case of only RC piers.
[0026]
[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a structural diagram schematically showing the structure of a reinforced concrete (RC) pier 1e (columnar member) of the present embodiment.
[0027]
The present embodiment is different from the first embodiment (only the lower end portion 2b) in that a retractable member such as a rubber member 7 is provided at both upper and lower end portions 2a, 2b of the core material 2. Since the configuration is the same, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0028]
As shown in FIG. 12, the upper and lower end portions 2 a and 2 b of the core member 2 are both installed on one fixing plate 6 a of the movable fixing member unit 5 via a rubber member 7. Therefore, the core material 2 is allowed to move upward and downward due to compression of the rubber member 7 so that the core material 2 can behave elastically in both large and small deformation regions of the pier. Adjustable.
[0029]
On the other hand, when the rubber member 7 of the fixing portion 5 at the upper and lower end portions 2a and 2b of the core member 2 is eliminated, the core member immediately responds to the external force acting on the pier as shown in FIG. 11 (d). 2 resists and the residual displacement becomes small as shown in FIG. 11 (e), but the amount of energy absorption at the time of the displacement is the same as that of the RC pier alone.
[0030]
In each of the above-described embodiments, the RC pier 1 has been described. However, the present invention is not limited to the RC pier 1 and can be applied to various other RC columnar members.
[0031]
【The invention's effect】
As is clear from the above description, according to the present invention, when the main reinforcing bar yields and enters the plastic zone at the time of large deformation of the columnar member, the high-strength core material elastically resists external force. In addition, the toughness of the columnar member is increased, the residual displacement is reduced by applying an elastic restoring force, and it becomes possible to meet the conflicting demands that the toughness is large and the residual displacement is small, and the columnar member is compressed. When receiving an external force, the lower end of the core member is in contact with the concrete casing, so that the core member resists, and the compressive strength of concrete that is inherently resistant to compression is further reinforced by the core member.
[Brief description of the drawings]
FIG. 1 is a structural diagram schematically showing the structure of a reinforced concrete (RC) pier according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
3 is a cross-sectional view taken along the line BB in FIG.
4 is a cross-sectional view taken along the line CC of FIG.
FIGS. 5A and 5B are cross-sectional explanatory views showing the structure of the main part of the first embodiment. FIGS.
FIGS. 6A and 6B are explanatory views showing a structural change example of a main part of the first embodiment. FIGS.
7A is a cross-sectional view taken along line EE in FIG. 5A, and FIG. 7B is a cross-sectional view taken along line FF in FIG. 6A.
FIG. 8 is an explanatory diagram showing another example in the structure change of the main part of the first embodiment.
FIG. 9 is an explanatory view showing the distortion of the core material in the first embodiment in comparison with a normal structure.
FIG. 10 is an explanatory diagram showing static characteristics of the first embodiment.
FIG. 11 is an explanatory diagram showing residual displacement in the first embodiment.
FIG. 12 is a structural diagram schematically showing the structure of a reinforced concrete (RC) pier according to a second embodiment of the present invention.
[Explanation of symbols]
1,1e Reinforced concrete (RC) pier (columnar member)
DESCRIPTION OF SYMBOLS 1a Concrete frame 1b Structural main reinforcement 1c Lateral restraint reinforcement 1d Foundation part 2 Core material 2a Upper end part 2b Lower end part 2c Press plate 3 Sheath pipe 4 Fixing part 5 Movable fixing member unit 6a, 6b Fixing plate 7 Rubber member (retractable) Element)
8 Coil spring (retractable member)
9 Disc spring (retractable member)
10 Casing 11 Opening

Claims

A standing concrete frame, a structural main reinforcement extending in the longitudinal direction of the concrete frame, and having a higher strength than the structural main reinforcement and extending substantially parallel to the inside of the main reinforcement In the columnar member made of reinforced concrete comprising the core material,
The core material is disposed separately from the surrounding concrete housing by an unbonded layer such as a sheath tube, and the upper and lower ends or the lower end of the core material is brought into contact with the concrete housing, the contact end portion of the core material and the A space between the fixing member disposed at the end of the unbonded layer is a retractable member disposed section, and the concrete frame can be relatively displaced toward the core one end by compression of the retractable member disposed in the section. A reinforced concrete seismic columnar member made of reinforced concrete that resists external force by the elastic action of the core material being transmitted to the concrete frame through the fixing member by eliminating the compression allowance of the compressible member when the columnar member is largely deformed .

2. The reinforced concrete earthquake-proof columnar member according to claim 1, wherein the contractible member is made of rubber, a coil spring, a disc spring, or the like.

The reinforced concrete seismic columnar member according to claim 1 or 2, wherein a compression allowance of the contractible member is set in consideration of a yield point displacement of the concrete frame and the main reinforcing bar.

The upper and lower end portions or the lower end portion of the core member is fixed to a movable fixing member unit embedded in a concrete frame, and the movable fixing member unit is disposed between upper and lower fixing plates disposed at a predetermined interval and both plates. A casing that is sandwiched and fixed, enters the casing through the opening of the fixing plate, the end portion contacts the fixing plate, and the end portion of the core member that fixes the pressing plate to the end portion, the pressing plate and the fixing plate, The reinforced concrete seismic columnar member according to any one of claims 1 to 3, wherein the seismic columnar member is composed of a retractable member disposed in a retractable member disposition section S.