JP2014125807A - Base isolation retrofit construction for existing building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective and suitable base isolation retrofit construction method by which, when an existing building is renovated into a building having base isolation structure by subjecting the existing building to base isolation retrofit, excavation work on a bearing ground under the existing building can be reduced as much as possible.SOLUTION: After existing foundations 4 of an existing building 1 to be renovated are reinforced through work from a floor right above the existing foundations 4 in order to use existing foundations 4 as an upper foundations 6 of the existing building 1 after being subjected to base isolation retrofit, the whole existing building is jacked up onto a bearing ground 9 to thereby secure a clearance 13 finally serving as a base isolation pit 12 between the bearing ground and upper foundations. Lower foundations are newly provided at a bottom part of the clearance, a base isolation device is installed between the lower foundations and upper foundations, and the whole existing building is supported in a base-isolated state by the base isolation device through the upper foundations.

Description

  The present invention relates to a seismic isolation method for renovating an existing building to a base-isolated structure.

  As is well known, in the seismic isolation structure in which the entire building is supported by seismic isolation so that it can be displaced in the horizontal direction (also in the vertical direction in the case of a 3D seismic isolation structure), the bottom of the base isolation pit provided on the foundation A lower foundation is installed on the bottom of the building, and the upper foundation is insulated from the lower foundation at the bottom of the building, and the entire building is installed via a seismic isolation device such as laminated rubber installed between the lower foundation and the upper foundation. It is fundamental to support seismic isolation.

  Recently, in order to improve the seismic performance of important buildings and historical buildings that have been constructed before, seismic isolation (so-called seismic isolation retrofit) is performed to upgrade existing buildings to seismic isolation structures. It has become like this.

As a method for making an existing building seismic isolation, as shown in Patent Document 1, for example, the entire existing building is supported by various underpinning methods, and the supporting ground under the existing foundation is excavated completely. The most common method is to form a seismic pit, construct a lower foundation at the bottom of the seismic isolation pit, install a seismic isolation device on the lower foundation, and use the seismic isolation device to support the entire existing building. is there.
In that case, since the existing foundation in the existing building needs to function as an upper foundation after the seismic isolation, it is necessary to reinforce in advance if the strength of the existing foundation is insufficient.

JP 2002-242450 A

  However, when a seismic isolation pit is formed in the conventional seismic isolation method as described above, a large-scale excavation work must be carried out on the supporting ground below the existing building. Since the work usually has to be an inefficient work in a narrow space where large heavy machinery cannot be used, it is inevitable that a large amount of repair cost and work period are required for that purpose.

  Therefore, in order to widely spread seismic isolation of existing buildings, it is necessary to reduce excavation work to the lower part of existing buildings as much as possible during seismic isolation. In fact, the development of seismic isolation methods is desired.

  In view of the above circumstances, the present invention is a seismic isolation method for renovating an existing building to a base-isolated structure, and the existing foundation in the target building to be refurbished is directly above the base after the seismic isolation. After reinforcing the work from the floor, by jacking up the entire existing building on the supporting ground, a clearance to be a seismic isolation pit is secured between the supporting ground and the upper foundation, and the clearance A base is newly installed at the bottom of the base, and a seismic isolation device is installed between the lower base and the upper base, and the seismic isolation device supports the entire existing building through the upper base. It is characterized by that.

According to the present invention, in order to form a seismic isolation pit as in the conventional general seismic isolation method, the entire existing building is not excavated for the entire supporting ground below the existing building. Since the seismic isolation pit is secured by jacking up, excavation to the lower part of the existing building only needs to be carried out to the minimum range necessary for reinforcing the existing foundation and jacking up, and thus the conventional Compared to the construction method, excavation work can be greatly reduced, which can reduce the construction cost and the construction period.
In addition, the conventional construction method mainly involves large-scale underground work for the underground part of the existing building, whereas the construction method of this embodiment is mainly for the work on the surface part from the inside and outside of the existing building. It can be greatly reduced, and in this respect, the workability can be greatly improved.

The embodiment of the seismic isolation method of the present invention is a schematic diagram showing the foundation of an existing building to be seismically isolated. It is a figure which shows the state which reinforces the existing foundation and newly established the upper foundation. It is a figure which shows the state which secured the clearance used as a seismic isolation pit by jacking up the whole existing building. It is a figure which shows a completion state similarly.

  Hereinafter, an embodiment of the seismic isolation method of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of a foundation of an existing building 1 to be repaired according to the present invention. In this existing building 1, the ground frame is made of steel with a steel column as an existing column 2 and a steel beam as an existing beam 3, and the existing foundation 4 is a direct foundation by a foundation beam 5 and a footing 16. It is what.

In this embodiment, when the existing building 1 is renovated into a base-isolated structure (is seismically isolated), the existing foundation 4 is first shown in FIG. 2 so that it can function as the upper foundation 6 after the renovation. In this way, reinforcement such as the addition of a reinforcing foundation beam 7 is performed at a point of the existing foundation 4.
The reinforcement work is performed from the floor directly above the existing foundation 4 (in the illustrated example, the first floor above the ground). For that purpose, the floor slab 8 on the first floor is disassembled to the extent necessary and the work from the inside of the existing building 1 is performed. An additional space for the reinforcing foundation beam 7 and a work space for the work may be secured by excavating the supporting ground 9 directly under the existing building 1 at necessary locations around the existing foundation 4.

Next, as shown in FIG. 3, the entire existing building 1 is jacked up.
That is, the required number of jacks 10 are installed at important points, and the jacks 10 are operated while being controlled in synchronization, and the entire existing building 1 is lifted and gradually raised.
At that time, the installation position of the jack 10 may be the position of the reinforcing foundation beam 7 directly below the existing pillar 2 or the surrounding area as shown in the figure, and if necessary, in order to secure the installation space of the jack 10 What is necessary is just to excavate the support ground 9 in the required minimum range.
The reaction force of the jack 10 can be secured without any trouble by various conventional underpinning methods. However, if necessary, it is important to provide an appropriate temporary foundation or constrain horizontal displacement during jack-up. It is only necessary to stably support the entire existing building 1 by installing a temporary horizontal restraint member 11 or the like.

As described above, the entire existing building 1 is jacked up, and a clearance 13 that finally becomes the seismic isolation pit 12 is secured between the upper foundation 6 (the existing foundation 4 after reinforcement) and the supporting ground 9.
The required height of the clearance 13 (that is, the distance to be raised by jacking up) also takes into account the plate thickness of the lower foundation 14 (not shown but including the lower foundation beam) to be post-worked and the height dimension of the seismic isolation device 15 Then, it may be set as appropriate so that the seismic isolation pit 12 having a predetermined height can be finally secured, but about 2 m is usually sufficient.

After securing the clearance 13 to be the seismic isolation pit 12 as described above, the lower foundation 14 (including the lower foundation beam) is newly installed on the bottom of the clearance 13 as shown in FIG. By installing the desired number of seismic isolation devices 15 on the main points (including the lower foundation beams) and joining the upper part to the upper foundation 6, existing seismic isolation devices 15 through the upper foundation 6 Seismic isolation support for the entire building 1.
Thereafter, the jack 10 and the horizontal restraint member 11 are removed, and if any other temporary material is installed, the temporary material is also removed.

  According to the seismic isolation method of this embodiment, instead of digging down the supporting ground 9 at the bottom of the existing building 1 in order to form the seismic isolation pit 12 as in the conventional general seismic isolation method, Conversely, since the seismic isolation pit 12 is formed by jacking up the entire existing building 1, excavation of the supporting ground 9 at the lower part of the existing building 1 is necessary to reinforce the existing foundation 4 and secure the installation space of the jack 10. Therefore, the excavation work can be greatly reduced as compared with the conventional method, so that the construction cost and the construction period can be shortened.

That is, in the case where a base isolation pit equivalent to the base isolation pit 12 constructed by the construction method of the present embodiment is excavated and constructed by the conventional construction method, the support ground 9 directly under the existing building 1 is shown by a chain line in FIG. However, in this embodiment, it is only necessary to excavate the surface part slightly shallower, and the cost and time required for the excavation can be greatly reduced compared to the conventional method. It becomes possible.
Moreover, in the conventional construction method, large-scale underground work for the lower part of the existing building 1 is mainly performed, whereas in the construction method of the present embodiment, the work on the ground surface portion from the inside and outside of the existing building 1 is mainly performed. In terms of reducing underground work, the workability can be greatly improved.

Of course, in the case of the construction method according to the present embodiment, not only the renovation accompanying the seismic isolation is required, but also the total height of the existing building 1 becomes higher by the amount jacked up than before the renovation. Therefore, the renovation work that accompanies it is of course necessary, but even if the entire building is about 2 meters high, for example, the convenience of use will not change, and the renovation costs for that purpose can be offset sufficiently by reducing excavation work. Is possible.
In addition, although the building height is increased by the renovation (seismic isolation) by the construction method of this embodiment, the area does not change, so it is not legally an extension, and it is a large scale that covers the majority of existing buildings It does not correspond to any renovation work, so it usually does not require complicated legal procedures such as application for confirmation.

  Although the embodiment of the present invention has been described above, the above embodiment is merely an example, the specific steps in the seismic isolation method of the present invention, the degree of reinforcement with respect to the existing foundation, the seismic isolation pit after repair, The specific configuration and other details of the seismic isolation device, etc. should be optimally designed in consideration of the structure and size of the existing building subject to seismic isolation, the required seismic isolation performance, the status of the supporting ground, and other conditions. It ’s fine.

  For example, the above embodiment is an application example in the case where the existing foundation of the existing building is a direct foundation, but even if the existing foundation is a pile foundation, only the repair to the pile head is necessary and the above-mentioned embodiment is substantially the above. The present invention can be applied by the same process as the embodiment.

DESCRIPTION OF SYMBOLS 1 Existing building 2 Existing pillar 3 Existing beam 4 Existing foundation 5 Foundation beam 6 Upper foundation 7 Reinforcement foundation beam 8 Floor slab 9 Support ground 10 Jack 11 Horizontal restraint member 12 Seismic isolation pit 13 Clearance 14 Lower foundation 15 Seismic isolation device 16 Footing

Claims (1)

A seismic isolation method for renovating an existing building to a seismically isolated building,
After reinforcing the existing foundation in the existing building to be refurbished from the upper floor to make it the upper foundation after seismic isolation,
By jacking up the entire existing building on a supporting ground, a clearance to be a seismic isolation pit is secured between the supporting ground and the upper foundation,
A lower foundation is newly installed at the bottom of the clearance, and a seismic isolation device is installed between the lower foundation and the upper foundation, and the entire existing building is seismically isolated via the upper foundation by the seismic isolation device. Seismic isolation method for existing buildings, characterized by support.

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