JP3536543B2 - Seismic isolation method for foundations of existing buildings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for isolating a base part of an existing building which is suitable for use in a case where a base part of an existing building supported by a pile foundation is seismically isolated by interposing a seismic isolation device. It is related to the seismic method.

[0002]

2. Description of the Related Art In general, buildings constructed before the current new seismic design method is enforced often have inferior seismic performance compared to buildings designed based on the new seismic design method. Therefore, in recent years, there has been an increasing demand for existing buildings that have been determined to have insufficient seismic performance to be seismically isolated buildings by performing seismic reinforcement. For this reason, various local seismic retrofitting methods have been proposed as a measure to reinforce an existing building having inferior seismic performance, for example, by adding an anti-seismic wall or reinforcing columns.

[0003]

However, inside the above-mentioned existing building, ordinary work and work are always performed. However, such construction such as the addition of earthquake-resistant walls and the reinforcement of pillars is difficult. In addition, it is necessary to carry various large members such as shoring and temporary reinforcing materials into the building and perform large-scale work.In addition, since the structure inside the building changes before and after reinforcement, There is a problem that it is difficult to perform the above-mentioned reinforcement work so as not to disturb the normal work. On the other hand, according to the method of seismic isolation of the entire building by interposing seismic isolation devices on the foundation of the existing building, the entire building can be seismically isolated, In order to work only under the foundation,
Although there are some restrictions, the building can be used almost as usual, and there is an advantage that there is very little change in the internal structure of the building before and after reinforcement.

[0004] However, when the foundation of the existing building is made seismic-isolated, after excavating under the foundation, the building is temporarily received, and then the jack is lifted up to support the axial load. Because it is necessary to install a seismic device,
There is a problem that a lot of labor is required for loading and unloading the shoring work and construction work for these jack-ups, and it is also necessary to ensure seismic safety during construction, such as when the load is temporarily supported by the jack-up. There was a problem, and a solution was strongly desired. The present invention was made in order to effectively solve various problems in seismic isolation of the foundation of such a conventional existing building, and the building can be used almost as usual during construction, and The purpose of the present invention is to provide a seismic isolation method for the foundation of an existing building that does not require jack-ups or other shoring work, greatly simplifies construction, and has excellent seismic safety during construction. It is.

[0005]

According to a first aspect of the present invention, there is provided a seismic isolation method for a foundation portion of an existing building, wherein a pile is exposed by excavating under a foundation of the existing building supported by a pile foundation, and then seismically isolated. After seismic reinforcement of multiple piles other than the pile where the device is to be installed, the pile where the seismic isolation device is to be installed is dismantled, and then a footing is newly installed under the relevant site. The upper and lower pedestals are installed in the upper and lower pedestals, and then a seismic isolation device is installed between the upper and lower pedestals, and a curable material is pressed into the gap between the upper and lower pedestals to preload the seismic isolation device. And then dismantling the other piles.

[0006] In this case, the invention according to claim 2 is that the seismic reinforcement of the pile is performed after the outer periphery of the pile is surrounded by the divided tubular member, and the divided parts are joined and integrated.
The non-shrinkage hardening material is filled and hardened between the tubular member and the pile, and the hardening is performed. On the other hand, the invention according to claim 3 performs seismic reinforcement of the pile, The method is characterized in that a carbon fiber sheet is wound after an adhesive is applied to the outer periphery of the pile, and the adhesive is cured and integrally joined.
Here, as the adhesive, it is preferable to use, for example, an adhesive which is easy to apply, such as an epoxy resin adhesive, and provides excellent curability and adhesiveness. Further, the invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein a shear connector is attached to a portion embedded in a new footing on the outer periphery of the seismically reinforced pile. It is characterized by putting.

In the invention according to any one of the first to fourth aspects, since the seismic isolation work is performed on the foundation of an existing building, the building can be used almost as usual, and before and after reinforcement. There is no need to change the internal structure of the building. In addition, at this time, by strengthening the piles other than the pile where the seismic isolation device is installed by seismic resistance, the strength of the piles is increased, ensuring safety during work and jacking up the building. Such a support work is not required, so that the work is greatly simplified. In addition, even in the event of an earthquake during construction, the above-mentioned seismic reinforcement will prevent the exposed areas of the piles from being sheared and destroyed, thus ensuring the seismic safety of the entire building. It becomes possible.

Here, as the seismic reinforcement of the pile, the outer periphery of the pile to be reinforced is surrounded by the divided tubular member and the divided parts are joined and integrated as in the invention according to claim 2. After that, it can be performed by filling a non-shrinkable curable material between the tubular member and the pile and curing the material. As the tubular member, a general steel pipe is preferable, and a steel pipe having an inner diameter slightly larger than the outer diameter of the pile is divided into two parts and arranged on the outer periphery of the pile, and the divided parts are joined and integrated. It is more preferable that the space between the piles is filled with non-shrinkable mortar or the like and hardened later, since the pile can be reinforced easily with a general-purpose pipe. Further, as another seismic reinforcement of the pile, as in the invention according to claim 3, an adhesive such as an epoxy resin adhesive is applied to the outer periphery of the pile to be reinforced, and then the carbon fiber sheet is applied. It may be performed by winding and curing the epoxy resin adhesive or the like.

Further, according to the invention described in claim 4,
In the invention according to any one of claims 1 to 3, by attaching a shear connector to a portion buried in a newly installed footing on the outer periphery of the reinforced pile,
The adhesion between the footing and the pile can be improved. If the shear connector is attached to the inner peripheral surface of the tubular member, for example, in the invention described in claim 2, the adhesive force between the curable material filled in the gap between the tubular member and the pile also increases. It is more preferable.
Incidentally, as the shear connector, a ring-shaped flat bar, a stud bolt, or the like is welded to the outer periphery of the reinforcing portion of the pile. In addition, when mounting on the inner peripheral surface of the tubular member, if the protrusion side of the checker plate is located in advance on the inner surface side of the tubular member, it is not necessary to separately perform complicated welding. Construction is easy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 6 are diagrams for explaining an embodiment of a method of seismic isolation of a foundation portion of an existing building according to the present invention. FIG. A plurality of independent footings 2 formed below the... Indicate an existing building before construction supported by a number of piles 3 driven into the ground. To perform seismic isolation on the foundation of such an existing building, first, as shown in FIG. 2, excavation is performed under the foundation of the existing building to expose the piles 3. At this time, the holes 4 are formed by excavating the piles 3... Deeper than other parts. In addition, by disassembling the pressure plate 5 in parallel with this, the burden on the piles 3 is somewhat reduced, and a wider working space is secured. Next, after the piles 3... Other than the pile 3 ′ at the site where the seismic isolation device is installed are washed, seismic reinforcement is applied to the outer periphery of the exposed portion indicated by oblique lines in the figure.

That is, as shown in FIG.
Roughening treatment is performed on the outer peripheral surface 3a of the slab, and then a half-split steel pipe (tubular member) 6 having an inner diameter larger than the outer diameter of the stake 3 is disposed on the outer periphery of the pile 3, and the divided portions 6a are joined by welding After that, the pile 3 is reinforced by filling the gap between the pile 3 and the steel pipe 6 with a non-shrinkable mortar (curable material) 7 and hardening. Here, the steel pipe 6
When there is a possibility that the adhesive force between the inner peripheral surface of the mortar 7 and the mortar 7 becomes insufficient, if the protrusion side of the checker plate is formed on the inner surface side of the steel pipe 6 in advance, the The adhesion can be increased to the desired strength. In this way, after increasing the strength of the piles 3 by seismic reinforcement, the piles 3 'at the site where the seismic isolation device is installed are dismantled.

Next, as shown in FIG. 4, concrete is poured into the holes 3 around the piles 3... At this time, if it is necessary to increase the adhesive force between the steel pipe 6 and the footing 8, a ring-shaped flat bar is welded to the outer peripheral surface of the steel pipe 6 in advance, or a stud bolt is welded. A so-called shear connector may be provided on the outer periphery of the steel pipe 6. And
After the footing 8 is constructed, the footing 8
The upper and lower pedestals 9 and 10 are constructed at the upper and lower positions of the seismic isolation device on the upper surface of the existing footing 2 and the lower surface of the existing footing 2, respectively. By doing so, a work space for maintenance and inspection is secured.

Next, as shown in FIG. 5, a seismic isolation device 12 made of, for example, a laminated rubber is installed between the upper and lower pedestals 9 and 10, and a gap between the seismic isolation device 12 and the upper pedestal 9 is provided. A mortar (curable material) 13 is charged under high pressure to apply a preload to the seismic isolation device 12. In this way, after supporting the load of the frame by the seismic isolation device 12, the exposed portions of the piles 3 are dismantled, and the unnecessary portion 2a of the existing footing 2 is also dismantled. And FIG.
As shown in the figure, the H steel pile 15 is buried in the excavated portion facing the buffer space 14 between the skeleton and the RC wall 17 is disposed via the earth anchor 16, and at the ground level of the skeleton, By newly providing the projecting slab 18 covering the buffer space 14, the seismic isolation of the building in which the seismic isolation device 12 is interposed in the foundation of the existing building is completed.

Therefore, according to the seismic isolation method for the foundation part of the existing building, most of the seismic isolation work on the existing building becomes the foundation part, so that the building can be used almost as usual. In addition, there is no need to cause a change in the internal structure of the building before and after reinforcement. In addition, in the seismic isolation work, the piles 3 other than the pile 3 ′ at the site where the seismic isolation device 12 is installed are reinforced with steel pipes 6 and mortar 7 to increase the resistance of the piles 3. As well as ensuring safety during work,
Furthermore, since the support work such as jacking up the building is not required, the seismic isolation work can be greatly simplified. In addition, even if an earthquake occurs during the construction, the piles 3 may be subjected to seismic reinforcement for the piles 3.
Since the exposed portion is prevented from being sheared and broken, it is also possible to ensure the earthquake resistance of the entire building during the work.

In the description of the above embodiment,
A case in which a half-split steel pipe 6 is arranged on the outer periphery of the pile 3 and integrated, and then the gap between the pile 3 and the steel pipe 6 is filled with non-shrinkable mortar 7 and hardened to reinforce the pile 3. However, the present invention is not limited to this. For example, an adhesive such as an epoxy resin adhesive is applied to the outer periphery of the pile 3 to be reinforced, and then a carbon fiber sheet is wound around the outer periphery and cured. Accordingly, the pile 3 may be reinforced by integrally attaching a carbon fiber sheet to the pile 3.

[0016]

As described above, according to the invention as set forth in any one of claims 1 to 4, the seismic isolation work for the existing building is exclusively used as the foundation, so that the building is almost normally used. It can be used and there is no need to change the internal structure of the building before and after reinforcement.
In addition, since several piles other than the pile where the seismic isolation device is installed are seismically reinforced, the strength of the piles can be increased to ensure safety during work, and the building can be jacked up. The work can be greatly simplified because the support work of the building becomes unnecessary, and the above-mentioned seismic strengthening prevents the exposed part of the pile from shearing and breaking. Excellent effects such as the ability to ensure seismic safety can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a building before construction in one embodiment of a method of seismic isolation of a foundation portion in an existing building of the present invention.

FIG. 2 is a longitudinal sectional view of a main part showing a state where a pile at a predetermined position is cut after excavation under the foundation in FIG. 1;

FIG. 3 is a cross-sectional view showing a structure of a reinforced pile in FIG. 2;

FIG. 4 is a longitudinal sectional view of a main part showing a state where a new footing and upper and lower pedestals are constructed from the state of FIG. 2;

5 is a longitudinal sectional view of a main part showing a state where a seismic isolation device is mounted between upper and lower pedestals in FIG. 4 and a pile is cut.

FIG. 6 is a longitudinal sectional view of a main part showing a state where seismic isolation of the existing building of FIG. 1 is completed.

[Explanation of symbols]

1 pillar 2 Footing (existing) 3 piles 3 'Pile where the seismic isolation device is installed 3a Outer peripheral surface 6 steel pipe (tubular member) 7. Non-shrink mortar (curable material) 8 Footing (newly established) 9 Upper pedestal 10 Lower pedestal 12 Seismic isolation device 13 Mortar (curable material)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-11720 (JP, A) JP-A-62-233385 (JP, A) JP-A-3-137326 (JP, A) JP-A-63-1987 118420 (JP, A) JP-A-2-20767 (JP, A) JP-A-64-31802 (JP, U) JP-A-62-129447 (JP, U) JP-B-6-25485 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) E02D 27/34 E02D 27/12 E04G 23/00-23/08

Claims (4)

(57) [Claims] 1. Excavation under the foundation of an existing building supported by a pile foundation to expose the pile, and then, after seismic strengthening of a plurality of piles other than the pile at the site where the seismic isolation device is to be installed, Disassemble the pile at the site where the pedestal is to be installed, then install a footing below the site, install the upper and lower pedestals at the upper and lower positions of the seismic isolation device, and then install the seismic isolation between these upper and lower pedestals. After installing a device, further press-fitting a curable material into the gap between the seismic isolation device and the upper pedestal and adding a preload to the seismic isolation device, dismantling the other piles in an existing building, Base seismic isolation method. 2. The seismic strengthening of the pile is performed by surrounding the outer periphery of the pile to be reinforced by the divided tubular member, joining the divided portions of the tubular member and integrating them, and then joining the tubular member with the divided member. The seismic isolation method for a foundation portion of an existing building according to claim 1, wherein a non-shrinkable hardening material is filled between the pile and the hardened material. 3. The seismic reinforcement of the pile is characterized in that an adhesive is applied to an outer periphery of the pile to be reinforced, a carbon fiber sheet is wound, and the adhesive is cured to be integrally joined. The method of seismic isolation of a foundation in an existing building according to claim 1. 4. An existing building according to claim 1, wherein a shear connector is attached to a portion of the outer periphery of the reinforced pile that is buried in the new footing. Base seismic isolation method.