JP3721498B2

JP3721498B2 - Seismic isolation method

Info

Publication number: JP3721498B2
Application number: JP22312899A
Authority: JP
Inventors: 昌一山中
Original assignee: Shimizu Corp
Current assignee: Shimizu Corp
Priority date: 1999-08-05
Filing date: 1999-08-05
Publication date: 2005-11-30
Anticipated expiration: 2019-08-05
Also published as: JP2001049891A

Description

【０００１】
【発明の属する技術分野】
本発明は、たとえば体育館のような形態の建物、すなわち内部が無柱空間とされる実質的に平屋建ての形態の既存建物を免震化するための免震化工法に関する。
【０００２】
【従来の技術】
周知のように、免震構造は建物全体を積層ゴム等の免震装置により水平方向に弾性的に支持することで実質的に地盤から絶縁して免震効果を得るものであり、近年広く普及する機運にある。そして、既存建物をそのような免震構造の建物に改修するための免震化も行われるようになってきており、最近では事務所や集合住宅といった一般的な用途の建物のみならず、たとえば体育館等の特殊な形態の建物に対しても免震化したいという要請がある。
【０００３】
ところで、体育館は、柱および梁を外周部にのみ設けて内部を無柱大空間とし、大階高ではあるものの構造的には実質的に平屋建ての形態とされることが一般的である。そのような形態の建物を免震化する場合の従来一般の工法を図３および図４に示す。図３は改修前、図４は改修後を示し、いずれも（ａ）は立面図、（ｂ）は平面図である。この既存建物１は、基礎２、外周柱３、外壁４、外周梁５、屋根６、床７により外殻が構成されて内部は無柱の大空間とされ、３階建て程度の高さを有するものであるが構造的には実質的に平屋建てとされているものである。この既存建物１を免震化するには、既存建物１を仮支持しつつその下方地盤全体（図４（ｂ）に斜線を付した範囲）を掘削して免震ピット８を形成し、その免震ピット８に積層ゴム等の免震装置９を設置してそれら免震装置９により既存建物１全体を支持せしめることになる。
【０００４】
図５および図６は、体育館を主建屋１２としてそれに３層の付属建屋１３を一体に設けた形態の既存建物１１を免震化する場合の例を示す（図５は改修前、図６は改修後を示し、いずれも（ａ）は平面図、（ｂ）は立面図である）。この場合も上記と同様に、既存建物１１全体を仮支持しつつその下方地盤全体（図６（ａ）に斜線を付した範囲）を掘削して免震ピット８を設け、そこに設置した免震装置９により既存建物１１全体（体育館である主建屋１２と付属施設である付属建屋１３の全体）を支持せしめることになる。なお、主建屋１２と付属建屋１３を切り離してそれらを独立に免震化したり、あるいは付属建屋１２のみを免震化することも考えられるが、その場合は主建屋１２と付属建屋１３とを切り離すための改修工事が大掛かりとなるし、それらが分断されることにより使い勝手が大きく悪化してしまうので、好ましくない。
【０００５】
【発明が解決しようとする課題】
従来の免震化工法では、免震ピット８を設けるために既存建物の下方地盤全体に対して大掛かりな掘削を行う必要があることから、そのための費用が嵩み、改修費用の大半が土工事に費やされてしまうものである。
【０００６】
また、改修対象の既存建物が図３や図５に例示した体育館のように内部が無柱大空間とされて構造的には実質的に平屋建てであるような場合、したがって既存建物自体が軽量であるような場合には、免震化による効果は必ずしも大きくなく、そのため改修費用に対して得られる効果が小さい嫌いがあり、不経済かつ不合理である。
【０００７】
上記事情に鑑み、本発明は特に体育館のような形態の既存建物を対象とする場合に好適な免震化工法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
請求項１の発明は、内部が無柱空間とされた実質的に平屋建ての既存建物を対象として免震化するための工法であって、該既存建物の外周部の下方地盤を掘削して免震ピットを設け、該免震ピットに該既存建物の外周部を支持する免震装置を設置し、該既存建物の基礎を外周部と内周部とに切り離して基礎外周部を前記免震装置に免震支持せしめるものである。
【００１０】
請求項２の発明は、内部が無柱空間とされた実質的に平屋建ての主建屋に対して複層の付属建屋が一体に設けられてなる既存建物を対象として免震化するための工法であって、付属建屋全体と主建屋外周部の下方地盤を掘削して免震ピットを設け、該免震ピットに付属建屋全体と主建屋外周部を支持する免震装置を設置し、主建屋の基礎を外周部と内周部とに切り離して、主建屋の基礎外周部と付属建屋全体を前記免震装置に免震支持せしめるものである。
【００１１】
【発明の実施の形態】
図１は本発明の第１実施形態である免震化工法を示す。これは図３に示した形態の既存建物１、すなわち内部が無柱大空間とされ大階高ではあるが構造的には実質的に平屋建ての建物を免震化する場合の適用例である。従来においては図４に示したように既存建物１の下方地盤全体を掘削して免震ピット８を全面的に設け、既存建物１全体を免震装置９により支持するものであったのに対し、本第１実施形態では、図１（ａ）に示すように既存建物１の外周部の下方地盤のみ（（ｂ）に斜線を付した範囲）を掘削してそこに免震ピット８を設けるに留めたものである。そして、既存建物１の基礎２を図中の絶縁線Ｃの位置で外周部２ａと内周部２ｂとに切り離し、外周部２ａのみを免震ピット８に設置した免震装置９により免震支持し、内周部２ｂは現状地盤に直接支持したまま残すようにしたものである。免震装置９としては一般的な積層ゴムの他、建物自重が特に軽量である場合にはボールベアリング等を用いる滑り支承によるものも好適に採用可能である。また、図示しているように既存基礎２の外周部２ａにコンクリートを増し打ちすれば、アウトリガー的な効果が高められて地震時に外周柱３に作用する引き抜き力や転倒モーメントに有効に抗することができる。
【００１２】
本第１実施形態の免震化工法では、免震ピット８を既存建物１の外周部にのみ設けることで良いので地盤掘削範囲が従来に比較して大幅に削減され、したがって掘削工事を大きく軽減できてその分のコストダウンを図ることができる。そして、免震化対象の既存建物１が外壁部および屋根部を主体として外殻が構成された形態、いわば中空箱を伏せたような形態であるので、内周部２ｂより切り離した基礎外周部２ａを介して免震装置９により建物の外殻としての外壁部および屋根部を免震支持するのみで、実質的にこの既存建物１全体を免震する場合と同等の効果が得られて建物全体を地震被害から守ることができる。
【００１３】
なお、このような構造であると建物内部に対する免震効果は得られないが、体育館のような内部が無柱大空間とされる建物では内部構造物が殆どなく、また床面への設置物も殆どないから、そのような形態の建物に適用する限りは建物内部の地震被害はさほど問題とならない。換言すれば、そのような形態の建物では建物内部に対してまで免震化する必要性は少なく、本実施形態のように建物の外殻のみを対象として免震化することで十分であるといえる。
【００１４】
図２は本発明の第２実施形態を示す。これは図５に示した既存建物１１、すなわち体育館を主建屋１２としてそれに３層の付属建屋１３を一体に設けた形態の建物を免震化する場合の適用例であり、主建屋１２の基礎２を絶縁線Ｃの位置で外周部２ａと内周部２ｂに切り離して、付属建屋１３全体と主建屋１２の外周部のみを免震装置９により免震支持し、主建屋１２の内周部はそのまま現状地盤に直接支持したままとしている。この場合も主建屋１２の内周部には免震ピット８を設ける必要がないので、その分、地盤掘削を削減し得てコストダウンを図ることができる。勿論、付属建屋１３全体に対してはもとより第１実施形態の場合と同様に体育館である主建屋１２全体に対する免震効果は支障なく得ることができる。
【００１５】
なお、本発明の免震化工法は、内部が無柱空間とされる実質的に平屋建ての既存建物であって内部に対する免震をさほど必要としない場合、換言すれば、建物の外殻を地震被害から守る必要はあるが内部構造物や内部設置物に対しては免震が要求されないような既存建物であれば、その用途や規模は特に限定されるものではなく、その限りにおいて体育館に限らず類似の形態の建物、たとえば講堂やホール、倉庫、工場といった用途の既存建物に適用することも考えられる。
【００１７】
【発明の効果】
請求項１の発明は、内部が無柱空間とされた実質的に平屋建ての既存建物を対象として免震化するに際し、既存建物の基礎を外周部と内周部に絶縁するとともに、外周部にのみ免震ピットを設けて基礎外周部のみを免震装置に免震支持せしめるので、十分な免震効果を得ることができるとともに、免震ピットは外周部にのみ設ければ良いので従来に比較してそのための地盤掘削工事を大幅に削減でき、免震化コストを十分に削減することができる。
【００１８】
請求項２の発明は、内部が無柱空間とされた実質的に平屋建ての主建屋と複層の付属建屋が一体に設けられてなる既存建物を対象として免震化するに際し、主建屋の基礎を外周部と内周部とに切り離して、主建屋の基礎外周部と付属建屋全体を免震装置に免震支持せしめるので、付属建屋はもとより主建屋に対しても十分な免震効果が得られるとともに、主建屋の内部における免震ピットは省略できるので免震化コストを削減でき、特に主建屋が体育館であり付属建屋がその付属施設である場合に適用して最適である。
【図面の簡単な説明】
【図１】本発明の第１実施形態である免震化工法の概要図である。
【図２】本発明の第２実施形態である免震化工法の概要図である。
【図３】免震化対象の既存建物の例を示す図である。
【図４】同既存建物を従来の免震化工法により免震化した状態を示す図である。
【図５】免震化対象の既存建物の他の例を示す図である。
【図６】同既存建物を従来の免震化工法により免震化した状態を示す図である。
【符号の説明】
１既存建物
２基礎
２ａ外周部
２ｂ内周部
３外周柱
４外壁
５外周梁
６屋根
７床
８免震ピット
９免震装置
１１既存建物
１２主建屋
１３付属建屋
Ｃ絶縁線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seismic isolation method for isolating a building in the form of, for example, a gymnasium, that is, an existing building in the form of a substantially one-story building whose interior is a column-free space.
[0002]
[Prior art]
As is well known, the seismic isolation structure, which is elastically supported in the horizontal direction by a seismic isolation device such as laminated rubber, effectively insulates the ground and obtains a seismic isolation effect. There is a moment to do. In addition, seismic isolation for renovating existing buildings to such seismic isolation structures has been carried out, and recently, not only general-purpose buildings such as offices and apartment buildings, There is a demand for seismic isolation for specially shaped buildings such as gymnasiums.
[0003]
By the way, a gymnasium is generally provided with pillars and beams only at the outer peripheral portion, and the interior is a large columnless space, and although it is a large floor, it is generally structured in a one-story building. A conventional general construction method for seismic isolation of such a building is shown in FIGS. FIG. 3 shows a state before renovation, FIG. 4 shows a state after renovation, and (a) is an elevation view and (b) is a plan view. This existing building 1 is composed of a foundation 2, an outer peripheral column 3, an outer wall 4, an outer peripheral beam 5, a roof 6, and a floor 7, and the inside is a large space without columns, and has a height of about three stories. Although it has, it is structurally substantially a one-story building. In order to make the existing building 1 seismic isolation, the existing ground 1 is temporarily supported and the entire lower ground (the range hatched in FIG. 4 (b)) is excavated to form the seismic isolation pit 8, A seismic isolation device 9 such as laminated rubber is installed in the seismic isolation pit 8 and the existing building 1 is supported by the seismic isolation device 9.
[0004]
5 and 6 show an example of a case where an existing building 11 having a gymnasium as a main building 12 and a three-layered annex building 13 is made to be seismically isolated (FIG. 5 is before renovation, FIG. (A) is a plan view and (b) is an elevation view). In this case, as in the case described above, the entire existing building 11 is temporarily supported and the entire lower ground (the hatched area in FIG. 6 (a)) is excavated to provide the seismic isolation pit 8 and the seismic isolation installed there. The seismic device 9 supports the entire existing building 11 (the main building 12 as a gymnasium and the entire ancillary building 13 as an accessory facility). In addition, it is possible to separate the main building 12 and the auxiliary building 13 and make them seismically isolated, or to isolate the auxiliary building 12 alone, but in that case, the main building 12 and the auxiliary building 13 are separated. This is not preferable because the renovation work is large and the usability is greatly deteriorated by dividing the work.
[0005]
[Problems to be solved by the invention]
In the conventional seismic isolation method, since it is necessary to perform extensive excavation for the entire ground below the existing building in order to provide the seismic isolation pit 8, the cost for that is increased, and most of the repair cost is earth work. It will be spent on.
[0006]
Further, in the case where the existing building to be refurbished is a columnar large space as in the gymnasium illustrated in FIG. 3 or FIG. In such a case, the effect of seismic isolation is not necessarily large, so there is a dislike for the effect obtained for the repair cost, which is uneconomical and unreasonable.
[0007]
In view of the above circumstances, an object of the present invention is to provide a seismic isolation method suitable for an existing building such as a gymnasium.
[0009]
[Means for Solving the Problems]
The invention of claim 1 is a method for seismic isolation for a substantially one-storied existing building whose interior is a column-free space, and excavates the lower ground of the outer peripheral portion of the existing building. A seismic isolation pit is provided, and a seismic isolation device is installed in the seismic isolation pit to support the outer periphery of the existing building. The base of the existing building is separated into an outer peripheral part and an inner peripheral part, and the base outer peripheral part is separated from the base isolation part. The device is to support seismic isolation.
[0010]
The invention according to claim 2 is a method for seismic isolation for an existing building in which a multi-layered annex building is integrally provided with respect to a substantially one-story main building whose interior is a column-free space. The base building and the lower ground of the main building outdoor perimeter are excavated to provide seismic isolation pits, and the base isolation building is installed in the base isolation pit to support the entire auxiliary building and the main building outdoor perimeter. The base is separated into an outer peripheral portion and an inner peripheral portion, and the base outer peripheral portion of the main building and the entire auxiliary building are supported by the seismic isolation device.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a seismic isolation method according to a first embodiment of the present invention. This is an application example in the case where the existing building 1 of the form shown in FIG. 3, that is, the interior is a pillarless large space and has a high floor but is structurally essentially a one-story building. . Conventionally, as shown in FIG. 4, the entire lower ground of the existing building 1 is excavated and the seismic isolation pit 8 is entirely provided, and the entire existing building 1 is supported by the seismic isolation device 9. In the first embodiment, as shown in FIG. 1 (a), only the lower ground of the outer peripheral portion of the existing building 1 is excavated (the range in which (b) is shaded) and a seismic isolation pit 8 is provided there. It is a thing kept in. The base 2 of the existing building 1 is separated into the outer peripheral portion 2a and the inner peripheral portion 2b at the position of the insulated wire C in the figure, and the base isolation is supported by the base isolation device 9 in which only the outer peripheral portion 2a is installed in the base isolation pit 8. However, the inner peripheral part 2b is left to be supported directly on the current ground. As the seismic isolation device 9, in addition to a general laminated rubber, a sliding bearing using a ball bearing or the like can be suitably employed when the weight of the building is particularly light. In addition, if concrete is added to the outer periphery 2a of the existing foundation 2 as shown in the figure, the outrigger-like effect is enhanced to effectively resist the pulling force and the overturning moment that act on the outer column 3 during an earthquake. Can do.
[0012]
In the seismic isolation method of the first embodiment, it is only necessary to provide the seismic isolation pit 8 only on the outer periphery of the existing building 1, so the ground excavation range is greatly reduced compared to the conventional one, and therefore excavation work is greatly reduced. The cost can be reduced accordingly. And since the existing building 1 to be seismically isolated has a form in which the outer shell is mainly composed of the outer wall part and the roof part, in other words, a form in which the hollow box is turned down, the foundation outer peripheral part separated from the inner peripheral part 2b The seismic isolation device 9 via 2a only provides seismic isolation support for the outer wall and roof as the outer shell of the building, and the effect is substantially the same as when the entire existing building 1 is isolated. The whole can be protected from earthquake damage.
[0013]
In addition, with such a structure, the seismic isolation effect on the inside of the building cannot be obtained, but in a building such as a gymnasium where the interior is a pillarless large space, there are almost no internal structures, and the installation on the floor surface However, as long as it is applied to such a building, earthquake damage inside the building will not be a problem. In other words, in such a building, there is little need for seismic isolation to the inside of the building, and it is sufficient to perform seismic isolation only for the outer shell of the building as in this embodiment. I can say that.
[0014]
FIG. 2 shows a second embodiment of the present invention. This is an application example in the case where the existing building 11 shown in FIG. 5, that is, a gymnasium as a main building 12 and a building in which three layers of ancillary buildings 13 are integrally provided, is seismically isolated. 2 is separated into the outer peripheral portion 2a and the inner peripheral portion 2b at the position of the insulated wire C, and the entire annex building 13 and only the outer peripheral portion of the main building 12 are seismically isolated by the seismic isolation device 9, and the inner peripheral portion of the main building 12 Remains directly supported by the current ground. Also in this case, since it is not necessary to provide the seismic isolation pit 8 in the inner peripheral part of the main building 12, ground excavation can be reduced correspondingly, and the cost can be reduced. Of course, the seismic isolation effect for the entire main building 12, which is a gymnasium, can be obtained without any trouble for the entire attached building 13 as well as the case of the first embodiment.
[0015]
In addition, the seismic isolation method of the present invention is an existing one- story building where the interior is a column-free space and does not require much seismic isolation for the interior. If it is an existing building that requires protection from earthquake damage but does not require seismic isolation for internal structures and installations, its use and scale are not particularly limited. The present invention can be applied to buildings of similar forms, such as existing buildings for uses such as auditoriums, halls, warehouses, and factories.
[0017]
【The invention's effect】
The invention of claim 1 insulates the base of the existing building from the outer peripheral part and the inner peripheral part when isolating the existing building with a substantially single-story structure with a pillar-free space. The seismic isolation pit is provided only on the base and only the outer periphery of the foundation is supported by the seismic isolation device, so that a sufficient seismic isolation effect can be obtained and the seismic isolation pit only needs to be provided only on the outer periphery. In comparison, the ground excavation work for that can be greatly reduced, and the seismic isolation cost can be sufficiently reduced.
[0018]
In the invention of claim 2, when the seismic isolation is applied to an existing building in which a substantially single-story main building and a multi-layered auxiliary building are integrally provided, the interior of the main building is The foundation is separated into an outer peripheral part and an inner peripheral part, and the base outer peripheral part of the main building and the entire ancillary building are seismically isolated and supported by the seismic isolation device, so there is sufficient seismic isolation effect for the main building as well as the auxiliary building. In addition, since the seismic isolation pits inside the main building can be omitted, the cost of seismic isolation can be reduced. In particular, it is optimally applied when the main building is a gymnasium and the ancillary building is its ancillary facility.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a seismic isolation method according to a first embodiment of the present invention.
FIG. 2 is a schematic view of a seismic isolation method according to a second embodiment of the present invention.
FIG. 3 is a diagram showing an example of an existing building to be seismically isolated.
FIG. 4 is a view showing a state in which the existing building is seismically isolated by a conventional seismic isolation method.
FIG. 5 is a diagram showing another example of an existing building to be seismically isolated.
FIG. 6 is a view showing a state in which the existing building is seismically isolated by a conventional seismic isolation method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Existing building 2 Foundation 2a Outer periphery 2b Inner periphery 3 Outer pillar 4 Outer wall 5 Outer beam 6 Roof 7 Floor 8 Seismic isolation pit 9 Seismic isolation device 11 Existing building 12 Main building 13 Attached building C Insulated wire

Claims

A method for seismically isolating an existing one-story building with a pillarless interior, and excavating the lower ground of the outer periphery of the existing building to provide a seismic isolation pit, Install a seismic isolation device to support the outer periphery of the existing building in the seismic isolation pit, separate the foundation of the existing building into an outer peripheral portion and an inner peripheral portion, and support the base outer peripheral portion with the seismic isolation device. Seismic isolation method characterized by

A method for seismic isolation of an existing building that has a multi-storey annexed building in addition to a substantially one-story main building with a column-free interior. And excavating the ground below the outer periphery of the main building to provide a seismic isolation pit, and installing the seismic isolation device to support the entire building and the main building outdoor periphery in the seismic isolation pit. A seismic isolation method characterized in that the base outer peripheral part of the main building and the entire ancillary building are seismically isolated and supported by the seismic isolation device.