JP3663557B2 - Base structure of seismic isolation structure - Google Patents

Base structure of seismic isolation structure Download PDF

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Publication number
JP3663557B2
JP3663557B2 JP08179296A JP8179296A JP3663557B2 JP 3663557 B2 JP3663557 B2 JP 3663557B2 JP 08179296 A JP08179296 A JP 08179296A JP 8179296 A JP8179296 A JP 8179296A JP 3663557 B2 JP3663557 B2 JP 3663557B2
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Prior art keywords
pile
base
foundation
pile head
ground
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Expired - Lifetime
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JP08179296A
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Japanese (ja)
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JPH09273162A (en
Inventor
和彦 磯田
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Shimizu Corp
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Shimizu Corp
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Description

【０００１】
【発明の属する技術分野】
本発明は積層ゴムを用いた免震構造物の基礎構造に関する。
【０００２】
【従来の技術】
周知のように、基礎部分に積層ゴムを介装して固有振動周期を長周期化することで免震効果を得る免震建築物が近年実現している。図２（ａ），（ｂ）はそのような免震建築物における基礎部分の最も一般的な例を示すもので、ピット１内の底部に下部構造たる基礎梁２を縦横に設けてその上部に積層ゴム３を設置し、それら積層ゴム３により上部構造物たる建屋４全体を水平変位可能に支持するようにしたものであり、建屋４の底部には積層ゴム３により支持される基礎梁５が縦横に設けられたものとなっている。
【０００３】
【発明が解決しようとする課題】
ところで、上記従来一般の構造においては、ピット１内と建屋４底部の双方に基礎梁２，５が二重に設けられるために通常の建築物に比して基礎の形態が複雑化しており、特にピット１内に基礎梁２を設けるために根切り底が深くなり、このため、仮設工事も含めて基礎工事の費用が嵩むのみならず工期短縮を図る上でも不利であり、このことが免震建築物の建設コスト削減を阻む一因となっていた。このため、免震建築物の施工に際して基礎工事を簡略化し、以て工費削減と工期短縮を図り得る有効な改善策が必要とされていた。
【０００４】
【課題を解決するための手段】
上記事情に鑑み、本発明は、基礎上に積層ゴムを介して上部構造物を支持してなる免震構造物の基礎構造であって、前記上部構造物の底部に基礎梁を設けるとともに、前記基礎を独立の杭のみから形成してそれら杭の間における基礎梁を省略し、前記杭を設けている地盤上には底盤を設けるとともに、該底盤には杭の直上位置に凸部を設けて、該凸部上に前記積層ゴムを設置し、かつ、前記底盤の凸部を杭頭部に対してダボ筋により連結して杭頭部を地盤に対してピン支承の形態で結合することにより、地盤に対する杭頭部の回転を拘束することなく許容する構造としたことを特徴とする。
【０００５】
【発明の実施の形態】
図１に本発明の一実施形態を示す。本実施形態では、上部構造物たる建屋４の底部には通常どうり基礎梁５を設けるものの、下部構造たる本来の基礎を独立の杭６のみにより構成し、図２に示したように従来一般にはピット１内にも設けられることが通常である基礎梁２は省略したものとなっている。
【０００６】
すなわち、本実施形態では、建屋４の底部に設けられている基礎梁５の直下に位置して独立の杭６が所定間隔で設けられているとともに、ピット１の底部には底盤７が全面にわたって設けられ、その底盤７には杭６の直上位置に凸部７ａが形成され、そこに積層ゴム３が設置され、それら積層ゴム３を介して建屋４の基礎梁５が杭６によって支持されるようになっている。
【０００７】
また、本実施形態では、上記杭６の杭頭部６ａと底盤７の凸部７ａとはダボ筋８により連結するのみとして杭６の主筋は底盤７に対してはアンカーせず、したがって構造的には杭頭部６ａを地盤に対してピン支承の形態で結合したものとして、杭頭部６ａの地盤に対する回転を拘束することなく許容する構造としている。なお、符号１０は捨てコンである。
【０００８】
上記構造によれば、従来においては設けることが通常であったピット１内の基礎梁２を省略したことにより、その基礎梁２を施工するに要していた鉄筋、型枠、コンクリートを削減できることはもとより、基礎梁２が省略されることで根切り底が浅くなるから山留め工事等の仮設工事を含む掘削工事も軽減され、以上のことから基礎工事に係わる作業とコストを大幅に軽減でき、工費削減と工期短縮に大きく寄与し得る。
【０００９】
また、本実施形態では、杭頭部６ａの地盤に対する回転を許容するようにしているために、杭頭モーメントがなくなるとともに杭６に生じる最大モーメントが杭頭固定の場合に比して２／３程度にまで低減するから、杭６に要求される曲げ性能を軽減し得るという利点もある。勿論、杭頭部６ａの回転を許容するといえども本実施形態において生じる杭頭部６ａの最大回転角は、Ｎ値が５以上の通常の地盤においては１／３００程度に過ぎず、これは通常の積層ゴム３の回転角の許容限度が１／２００程度であることを考慮すれば何等問題とならない。また、本実施形態では、杭頭部６ａを固定した場合に比して水平変位が２倍程度となるが、これも通常は１〜２ｃｍ程度に過ぎず、一般の積層ゴム３の許容水平変形量は３０ｃｍ程度であることからこれも何等支障はない。
【００１０】
なお、上記実施形態において地盤が良好な場合には底盤７を省略して捨てコン１０のみとすることも可能である。
【００１１】
【発明の効果】
以上のように、本発明は、免震構造物における基礎を独立の杭のみで構成してそれらをつなぐ基礎梁を省略したものであるから、基礎工事を大幅に簡略化し得て工費削減、工期短縮に大きく寄与し得る。特に、杭の直上位置に底盤の凸部を設けてその凸部上に積層ゴムを設置するとともに、杭頭部と凸部とをダボ筋により連結して杭頭部を地盤に対してピン支承の形態で結合することにより地盤に対する杭頭部の回転を拘束することなく許容する構造としたので、杭頭モーメントがなくなりかつ杭に生じる最大モーメントが低減するという利点がある。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す要部断面図である。
【図２】従来一般の免震構造物における基礎部分を示す図であり、（ａ）は立面図、（ｂ）は平面図である。
【符号の説明】
３ 積層ゴム
４ 建屋（上部構造物）
５ 建屋の基礎梁
６ 杭
６ａ 杭頭部
７ 底盤
７ａ 凸部
８ ダボ筋
１０ 捨てコン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a basic structure of a base isolation structure using laminated rubber.
[0002]
[Prior art]
As is well known, seismic isolation buildings have been realized in recent years that obtain a seismic isolation effect by interposing a laminated rubber in the base portion to increase the natural vibration period. 2 (a) and 2 (b) show the most common example of the foundation part in such a base-isolated building. The base beam 2 as the lower structure is provided vertically and horizontally at the bottom of the pit 1 and the upper part thereof. The laminated rubber 3 is installed on the building 4 so that the entire building 4 as an upper structure is supported by the laminated rubber 3 so as to be horizontally displaceable. The base beam 5 supported by the laminated rubber 3 is supported at the bottom of the building 4. Is provided vertically and horizontally.
[0003]
[Problems to be solved by the invention]
By the way, in the conventional general structure, since the foundation beams 2 and 5 are provided in both the inside of the pit 1 and the bottom of the building 4, the form of the foundation is complicated compared to a normal building, In particular, since the foundation beam 2 is provided in the pit 1, the root depth becomes deep, which not only increases the cost of foundation work, including temporary work, but is also disadvantageous for shortening the construction period. This was one of the factors that hindered the construction cost reduction of seismic buildings. For this reason, there has been a need for effective improvement measures that can simplify the foundation work and reduce the construction cost and the construction period when constructing the base-isolated building.
[0004]
[Means for Solving the Problems]
In view of the above circumstances, the present invention is a base structure of a seismic isolation structure that supports an upper structure via a laminated rubber on a foundation, and a foundation beam is provided at the bottom of the upper structure, The foundation is formed only from independent piles, the foundation beams between the piles are omitted, and a bottom plate is provided on the ground where the piles are provided, and a convex portion is provided on the bottom plate at a position directly above the pile. By installing the laminated rubber on the convex part, and connecting the convex part of the bottom plate to the pile head by a dowel bar and connecting the pile head to the ground in the form of a pin support. The structure is such that the rotation of the pile head relative to the ground is allowed without restriction.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention. In this embodiment, although the foundation beam 5 is usually provided at the bottom of the building 4 that is the upper structure, the original foundation that is the lower structure is constituted by only the independent piles 6, and as shown in FIG. The foundation beam 2 that is usually provided in the pit 1 is omitted.
[0006]
That is, in this embodiment, the independent piles 6 are provided at predetermined intervals directly below the foundation beam 5 provided at the bottom of the building 4, and the bottom plate 7 is provided over the entire surface at the bottom of the pit 1. Protrusions 7 a are formed on the bottom plate 7 at positions directly above the pile 6, the laminated rubber 3 is installed there, and the foundation beam 5 of the building 4 is supported by the pile 6 via the laminated rubber 3. It is like that.
[0007]
Moreover, in this embodiment, the pile head 6a of the said pile 6 and the convex part 7a of the bottom board 7 are connected only by the dowel reinforcement 8, and the main reinforcement of the pile 6 does not anchor to the bottom board 7, Therefore, it is structural. The pile head 6a is coupled to the ground in the form of a pin support, and the structure allows the rotation of the pile head 6a with respect to the ground without being restricted. In addition, the code | symbol 10 is a discard con.
[0008]
According to the above structure, by omitting the foundation beam 2 in the pit 1 that was normally provided in the past, it is possible to reduce the reinforcing bars, formwork, and concrete required to construct the foundation beam 2 Of course, the foundation beam 2 is omitted, so that the bottom of the root becomes shallower, so excavation work including temporary work such as mountain retaining work is also reduced. From the above, the work and costs related to the foundation work can be greatly reduced. It can greatly contribute to reduction of construction cost and construction period.
[0009]
Moreover, in this embodiment, since the rotation of the pile head 6a with respect to the ground is allowed, the pile head moment disappears and the maximum moment generated in the pile 6 is 2/3 as compared with the case where the pile head is fixed. Since it reduces to a grade, there also exists an advantage that the bending performance requested | required of the pile 6 can be reduced. Of course, although the rotation of the pile head 6a is allowed, the maximum rotation angle of the pile head 6a generated in the present embodiment is only about 1/300 in a normal ground having an N value of 5 or more. Considering that the allowable limit of the rotation angle of the laminated rubber 3 is about 1/200, there is no problem. Moreover, in this embodiment, although horizontal displacement becomes about 2 time compared with the case where the pile head 6a is fixed, this is also usually only about 1-2 cm, and the allowable horizontal deformation | transformation of the general laminated rubber 3 is carried out. Since the amount is about 30 cm, this is no problem.
[0010]
In the above embodiment, when the ground is good, the bottom board 7 may be omitted and only the throwing away container 10 may be used .
[0011]
【The invention's effect】
As described above, the present invention consists of the foundations in the seismic isolation structure consisting of only independent piles, and the foundation beams connecting them are omitted, so that the foundation work can be greatly simplified and the construction cost can be reduced. This can greatly contribute to shortening. In particular , a convex part of the base is provided at the position directly above the pile, and laminated rubber is installed on the convex part, and the pile head is connected to the ground with a dowel bar to connect the pile head to the ground. Since the structure allows the rotation of the pile head with respect to the ground without constraining it, there is an advantage that the pile head moment is eliminated and the maximum moment generated in the pile is reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part showing an embodiment of the present invention.
2A and 2B are diagrams showing a basic portion in a conventional general seismic isolation structure, where FIG. 2A is an elevation view and FIG. 2B is a plan view.
[Explanation of symbols]
3 Laminated rubber 4 Building (superstructure)
5 Building foundation beam 6 Pile 6a Pile head 7 Bottom
7a Convex 8 Dowel Muscle 10 Discarded Con

Claims (1)

基礎上に積層ゴムを介して上部構造物を支持してなる免震構造物の基礎構造であって、
前記上部構造物の底部に基礎梁を設けるとともに、前記基礎を独立の杭のみから形成してそれら杭の間における基礎梁を省略し、
前記杭を設けている地盤上には底盤を設けるとともに、該底盤には杭の直上位置に凸部を設けて、該凸部上に前記積層ゴムを設置し、
かつ、前記底盤の凸部を杭頭部に対してダボ筋により連結して杭頭部を地盤に対してピン支承の形態で結合することにより、地盤に対する杭頭部の回転を拘束することなく許容する構造としたことを特徴とする免震構造物の基礎構造。A base structure of a base-isolated structure that supports an upper structure via laminated rubber on the base,
While providing a foundation beam at the bottom of the upper structure, the foundation is formed only from independent piles and the foundation beam between these piles is omitted,
On the ground on which the pile is provided, a bottom plate is provided, and the bottom plate is provided with a convex portion directly above the pile, and the laminated rubber is installed on the convex portion,
And by connecting the convex part of the bottom base to the pile head with a dowel bar and connecting the pile head to the ground in the form of a pin support, without restricting the rotation of the pile head relative to the ground Basic structure of seismic isolation structure, characterized by an acceptable structure.
JP08179296A 1996-04-03 1996-04-03 Base structure of seismic isolation structure Expired - Lifetime JP3663557B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP08179296A JP3663557B2 (en) 1996-04-03 1996-04-03 Base structure of seismic isolation structure

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP08179296A JP3663557B2 (en) 1996-04-03 1996-04-03 Base structure of seismic isolation structure

Publications (2)

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JPH09273162A JPH09273162A (en) 1997-10-21
JP3663557B2 true JP3663557B2 (en) 2005-06-22

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007120232A (en) * 2005-10-31 2007-05-17 Shimizu Corp Base isolation structure of pile head

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002105970A (en) * 2000-09-28 2002-04-10 Daiwa House Ind Co Ltd Base isolation building
JP6030873B2 (en) * 2012-07-13 2016-11-24 株式会社熊谷組 Pile foundation structure

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007120232A (en) * 2005-10-31 2007-05-17 Shimizu Corp Base isolation structure of pile head

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