JPH09170340A - Base isolation method of existing building and base isolation device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base isolation device capable of reducing a construction period of time and curtailing a construction cost, quickly damping seismic force irrespective of simple construction and controlling horizontal displacement within allowable range. SOLUTION: A base isolation device 32 is so constituted that a reinforced concrete bearing pile is buried in the ground from the lower part 11 of a skeleton in the existing building and that it is provided between the lower part of the skeleton and a pile head 14a of the bearing pile. Concrete of the pile head 14a of the bearing pile is crushed in a state to expose pile reinforcement, the pile reinforcement extended between the lower part of the skeleton and pile head without being cut off is used as steel bar dampers 22b plastically deformed by horizontal input when an earthquake occurs. The pile reinforcement cut off other than the steel bar dampers 22b is used as auxiliary steel bar damper 22a. A bearing device 28 capable of being elastically deformed in the horizontal direction is provided between the upper surface of the pile head and lower surface of the lower part of the skeleton.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation method for an existing building and a seismic isolation device for an existing building, in which a seismic isolation device is newly installed on the foundation of an already constructed existing building.

[0002]

2. Description of the Related Art In recent years, various seismic isolation construction methods have been developed which have a structure in which the seismic force at the time of earthquake occurrence is not directly transmitted to the building and reduce the shaking of the building as much as possible to prevent the destruction of the building. By the way, when adopting the seismic isolation method for a new building, the seismic isolation method can be easily performed only by increasing the construction cost, but for example, it is buried in the soil of an already constructed existing building. When installing a new seismic isolation device on the existing foundation, the seismic isolation device must be installed on the foundation while always receiving the vertical load of the existing building. There is a problem in ensuring the seismic isolation performance of existing buildings.

Therefore, as a technique for solving the above problems,
For example, a seismic isolation method for existing buildings, which is described in JP-A-2-20767, is known. This seismic isolation method is
At the stage where the basement of the existing building is cut off to expose the support piles to the support layer ground, and the required number of temporary support supports are built around the exposed support piles.Jacks are installed on each temporary support. A step of working with the underground structure frame of the existing building to relocate the bearing axial load of the support pile to a temporary support, and after relocating the axial force, dismantle the support pile,
Instead, install the main steel column at the same position and install a seismic isolation device between the main steel column and the underground structure frame of the existing building, and then add the axial force of the temporary support to the main steel frame. It is a construction method that includes the steps of remounting the pillars and removing the temporary support.

According to this seismic isolation method, after undergrounding an existing building to form an underground space, the existing building is supported by a temporary support and a jack, and is installed at the position of the dismantled support pile. Since the steel columns and the seismic isolation device are installed and the existing building is supported by these, the construction safety can be secured and the seismic isolation performance of the existing building can be surely secured.

[0005]

However, the technique described in the above-mentioned Japanese Patent Laid-Open No. 2-20767 has the following problems.
At this stage, the work of loading the temporary support, jacks, and steel columns from the ground to the underground space is carried out, and at the above stage, the work of the used temporary support and jacks is carried out from the underground space to the ground. A lot of time is spent in loading and unloading a large amount of construction materials. In addition, at the above-mentioned stage, a large underground space must be formed so that the support piles buried deep in the ground are exposed up to the supporting layer ground, and many excavations are required to form this large underground space. Need a period.

Therefore, it is difficult for the above-mentioned conventional technique to shorten the construction period and the construction cost. Further, in the above-mentioned conventional technology, a large number of seismic isolation devices installed between the main steel column and the underground structure frame of the existing building absorb the horizontal input at the time of the occurrence of the earthquake and reduce the horizontal displacement of the existing building. In order to keep it within the allowable range, it is necessary to use expensive seismic isolation devices such as lead-containing laminated rubber and high damping laminated rubber,
Further, the construction cost may be increased.

The present invention has been made in view of the above circumstances, and aims to shorten the construction period and the construction cost, promptly attenuate the seismic force in spite of a simple structure, and horizontally displace it. It is an object of the present invention to provide a seismic isolation method for an existing building and a seismic isolation device for an existing building that employs a seismic isolation device that can control the amount within an allowable range.

[0008]

In order to solve the above problems, in the seismic isolation method for an existing building according to claim 1, the ground immediately below the lower part of the structure is rooted along the lower part of the structure of the existing building. By forming an underground space by this, the step of exposing only the pile heads of the reinforced concrete support piles buried in the soil from the lower part of the skeleton in this underground space, and erected temporary support in the underground space. The step of causing the temporary support to bear the vertical load of the existing building, which is borne by the support pile, and crushing the concrete of the pile head immediately below the lower part of the skeleton, and being fixed inside this concrete A step of extending a plurality of pile reinforcing bars in a vertical direction between the lower part of the frame and the pile head in a bare state, and a predetermined number of the pile reinforcing bars of the plurality of bare pile reinforcing bars to generate an earthquake Water of time Using as a steel rod damper that plastically deforms by inputting the direction, and installing a horizontally elastically deformable bearing device between the upper surface of the pile head and the lower surface of the lower frame, A method of releasing the support of the existing building by the receiving support and introducing a vertical load of the existing building into the support pile via the support device.

In the seismic isolation device for an existing building according to claim 2, a support pile made of reinforced concrete is buried in the soil from the lower part of the frame of the existing building, and between the lower part of the frame and the pile head of the support pile. In the seismic isolation device, the concrete of the pile head of the support pile is crushed to expose the pile rebar, and a predetermined number of these pile rebars are placed between the lower part of the frame and the support pile. A spare steel rod damper is cut and the remaining pile rebar that is not cut and extends between the lower part of the frame and the pile head is a steel rod damper that is plastically deformed by horizontal input when an earthquake occurs. In addition, a supporting device that is elastically deformable in the horizontal direction is installed between the upper surface of the pile head and the lower surface of the lower frame.

According to a third aspect of the present invention, in the seismic isolation device for an existing building according to the second aspect, a device in which the lower side of the body of the steel rod damper and the head side of the pile are fixed by a deformation preventing member. Is. Further, the invention according to claim 4 is the seismic isolation device for an existing building according to claim 3, wherein a vertical width of a deformation preventing member fixed to the lower body side of the steel rod damper and the pile head side is It is a device for changing and adjusting the plastic deformation region of the steel rod damper between these deformation preventing members.

According to a fifth aspect of the present invention, a support pile made of reinforced concrete is buried in the soil from the lower part of the frame of the existing building, and is interposed between the lower part of the frame and the pile head of the support pile. A seismic isolation device, in which the concrete of the pile head of the support pile is crushed to expose the pile rebar, and all of these pile rebars are cut at the pile head side, and the cut end of a predetermined number of pile rebars. Inserted into the inside of a plurality of steel pipes that are fixed to the upper surface of the pile head, the pile rebar inserted cutting ends inside these steel pipes, as a steel rod damper plastically deformed by the horizontal input when an earthquake occurs, The remaining pile reinforcing bars are used as spare steel rod dampers, and a horizontally elastically deformable support device is installed between the upper surface of the pile head and the lower surface of the lower part of the frame.

According to a sixth aspect of the present invention, in the seismic isolation device for an existing building according to the fifth aspect, the steel rod damper is fixed to the lower side of the skeleton by a deformation preventing member. Furthermore, the invention according to claim 7 is the seismic isolation device for an existing building according to claim 6, wherein the vertical width of the deformation preventing member fixed to the lower side of the body of the steel rod damper is changed to prevent the deformation. An apparatus for adjusting a plastic deformation region of the steel rod damper between a member and the steel pipe.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment according to the present invention will be described below with reference to FIGS. FIG. 1 shows an existing building 10 for which the seismic isolation method is used. The existing building 10 has a plurality of support piles 14 extending from a footing (lower part of the skeleton) 11 at the bottom of the building to a support layer ground 12. It is supported. Here, the support pile 14 is a cast-in-place concrete pile, and a plurality of pile reinforcements extending vertically in the columnar concrete and a plurality of hoop reinforcements surrounding the periphery of these pile reinforcements. The reinforcement is arranged, and the main rebar extends to the inside of the footing 11.

In the present embodiment, first, as shown in FIG. 2, a mountain retaining wall 16 that also serves as a water stop is buried in the soil around the existing building 10. And this mountain stop wall 16
After the burial is completed, the soil between the existing building 10 and the retaining wall 16 is excavated to form the space 18. Next, the soil is excavated in a horizontal direction from the bottom of the footing 11 to a position slightly deeper toward the existing building 10, and the root of the existing building 10 immediately below the footing 11 is cut off. As a result, the existing building 10
The pile heads 14a of the respective support piles 14 are exposed in an underground space that horizontally extends with the lower surface of the foundation as a ceiling. Then, a plurality of temporary receiving supports (not shown) are erected on the ground of the underground space 20, and the existing building 1 is provided by these temporary receiving supports.
Temporarily receives a vertical load of 0.

Next, as shown in FIGS. 3 (a) and 3 (b), the upper concrete of the pile head 14a exposed in the underground space 20 is crushed (in the area indicated by the chain double-dashed line in the figure), and the pile head is crushed. A plurality of pile reinforcing bars 22 extending in the vertical direction from 14a toward the footing 11 are exposed. Here, the upper end surface 24 of the pile head 14a formed by crushing concrete is separated from the bottom surface 11a of the footing 11 in parallel and is a flat surface. In these figures, the hoop reinforcement arranged around the outer circumference of each pile rebar 22 is
Not shown as already removed.

Next, as shown in FIGS. 4 (a) and 4 (b), a predetermined number of pile reinforcing bars 22 among the pile reinforcing bars 22 exposed in the underground space 20 are cut. That is, of the plurality of pairs of pile rebars 22 having the axial center P of the pile head 14a as the point-symmetrical position,
A predetermined pair of pile rebars 22 are cut at the center in the length direction. Then, the cut pile rebars 22 are bent to the outer peripheral side of the pile head 14a so that the cut portions are separated from the axis P. Here, the cut pile rebar is referred to as a spare steel rod damper indicated by reference numeral 22a, and the footing 1 is not cut from the pile head 14a.
The pile reinforcing bar extending toward 1 is referred to as a steel rod damper indicated by reference numeral 22b.

Next, as shown in FIGS. 5 (a) and 5 (b), the lower surface 11a of the footing 11 and the upper end surface 24 of the pile head portion 24.
An isolator (bearing device) 28 is installed between and. The isolator 28 employs a laminated rubber bearing in which metal plates such as iron plates and rubber are alternately laminated, and flanges 28a and 28b are provided on the upper and lower end surfaces thereof. Then, attach the flanges 28a and 28b to the footing 1
The lower surface 11a of No. 1 and the upper end surface 24 of the pile head 14a are brought into contact with each other and fixed via anchor bolts (not shown). As a result, the isolator 28 installed between the pile head 14a and the footing 11 receives the vertical load of the existing building 10 while being elastically deformable in the horizontal direction.

Next, as shown in FIGS. 6A and 6B, the outer circumference of the steel rod damper 22b located on the lower surface 11a side of the footing 11 and the steel rod damper located on the upper end surface 24 side of the pile head 14a. 22b around the outer circumference of the steel rod damper 22
The steel strips 30a and 30b are fixed so as to surround b from the outer peripheral side. Here, as shown in FIG. 6 (a), the strip steels 30a, 3
The length of the steel rod damper 22b between 0b is referred to as a flexible region L ₁ .

Then, the temporary support temporarily receiving the vertical load of the existing building 10 is removed, and the vertical load of the existing building 10 is introduced into the support pile 14 via the isolator 28.
Further, the isolator 28 is also installed on the other support piles 14 by the procedure described above, and the vertical load of the existing building 10 is introduced into the support piles 14 via the isolator 28. Thus, in the first embodiment, the isolator 28 installed between the lower surface 11a of the footing 11 and the upper end surface of the pile head 14a.
And a plurality of steel rod dampers 22b extending between the footing 11 and the pile head 14a constitute a seismic isolation device 32. The seismic isolation device 32 corresponds to the intensity of the earthquake and is shown in FIGS.
The behavior shown in is shown. 7 and 9, the spare steel rod damper 22a is omitted.

That is, when a small-scale earthquake occurs, the isolator 28 is elastically deformed by a small displacement δ ₁ in the horizontal direction as shown in FIG. 7, and the steel rod damper 22b is
As shown in FIG. 8, in the flexible region L ₁ , bending plastic deformation in both positive and negative horizontal directions is caused. Then, the seismic force is promptly attenuated by absorbing the hysteresis energy due to the bending plastic deformation of the steel rod damper 22b.

When a large-scale earthquake occurs, the isolator 28 is displaced by a large horizontal displacement δ as shown in FIG.
₂ is elastically deformed, and the steel rod damper 22b is
As shown in 0, in the flexible region L ₁ , tensile plastic deformation in one horizontal direction is caused. Then, the seismic force is quickly attenuated by absorbing the hysteresis energy due to the tensile plastic deformation of the steel rod damper 22b, and the horizontal displacement amount of the existing building 10 is suppressed within the allowable range.

Therefore, in the first embodiment described above, only the small underground space 20 is formed so that only the pile heads 14a of the support piles 14 are exposed. The required period is short, and a large number of construction materials (jacks, temporary support, steel frame pillars, etc.) are not required unlike the prior art, so the construction period can be shortened.

The pile head 14 directly below the footing 11
The concrete of a is crushed and removed to expose the pile rebar of the support pile 14, and a plurality of pile rebars extending between the pile head 14a and the footing 11 among these pile rebars are attached to the steel bar damper 22.
Used as b, footing 11 and pile head 1
The seismic isolation device 32 is configured by installing the isolator 28 that receives a vertical load of the existing building 10 so as to be elastically deformable in the horizontal direction between the seismic isolation device 32 and 4a. Since the seismic force is promptly attenuated by absorption and the horizontal displacement of the existing building 10 is suppressed within the allowable range, the seismic isolation device 32 can be installed at a lower cost than the related art. Thereby, the construction cost can be sufficiently reduced.

Further, the lower surface 11a side of the footing 11 of the plurality of steel rod dampers 22b and the upper end surface 24 of the pile head 14a.
The strip steels 30a and 30b arranged so as to surround the side are the lower surface 11a side of the footing 11 and the upper end surface 24 of the pile head 14a.
The plastic deformation of the steel rod damper 22b on the side is prevented. Thereby, when the steel rod damper 22b is plastically deformed, the footing 1
The concrete of the lower surface 11a of 1 and the concrete of the upper end surface 24 of the pile head 14a are not damaged.

When the cut spare steel rod damper 22a is fixed again, it is possible to change the damping force of the steel rod damper 22b and to use it as a replacement steel rod damper. Then, as shown in FIG. 11, the first
It is a modification of the seismic isolation device used in the embodiment. In this seismic isolation device 34, the strip steels 30a and 30b are arranged at positions close to each other, and the strip steel 30a and the lower surface 11a of the footing 11 are arranged.
As a structure in which a spiral reinforcing bar 36a is fixed to the outer circumference of the steel rod damper 22b between them, and a spiral reinforcing bar 36b is also fixed to the outer circumference of the steel rod damper 22b between the band steel 30b and the upper end surface 28 of the pile head 14a. There is. As a result, the seismic isolation device 34 of the present embodiment has a flexible region L as compared with the device shown in FIG.
₂ (L ₂ <L ₁ ) is set short.

When the flexible region L ₂ is appropriately changed as in the above structure, the plastic deformation region of the steel rod damper 22 increases or decreases, so that the damping force of the steel rod damper 22b can be adjusted and the existing building 10 can be adjusted. The amount of horizontal displacement can also be adjusted within a predetermined range. Next, FIG. 12 to FIG.
It shows a second embodiment according to the present invention. The same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Further, the steps of FIGS. 1, 2 and 3 shown in the first embodiment are performed as initial steps also in the present embodiment. In addition, after the process of FIG. 2, the existing building 10 is supported by a plurality of temporary receiving supports that are erected on the ground of the underground space 20.
It is assumed that the vertical load of is temporarily received.

Then, as shown in FIG. 12 performed after the step of FIG.
In the steps shown in (a) and (b), the lower ends (ends on the pile head 14a side) of all the pile reinforcing bars 22 exposed in the underground space 20 are cut. Then, of a plurality of pairs of pile rebars 22 with the axial center P of the pile head 14a being a point-symmetrical position, a predetermined pair of pile rebars 22
Are bent to the outer peripheral side of the pile head 14a so that the cut portions are separated from the axis P. Here, the pile rebar bent on the outer peripheral side of the pile head 14a is referred to as a spare steel rod damper indicated by reference numeral 44a, and the pile rebar that is not bent and extends toward the upper end surface 24 of the pile head 14a is indicated by reference numeral 44b. It is called a steel rod damper shown in.

Then, as shown in FIGS. 13 (a) and 13 (b), the tip of the steel rod damper 44b is inserted into the upper end surface 24 of the pile head 14a at a position facing the tip of the steel rod damper 44b. The plurality of steel pipes 46 thus fixed are fixed. Then, in FIG.
As shown in (a) and (b), the bottom surface 1 of the footing 11 is
An isolator (support) 28 is installed between 1a and the upper end surface 24 of the pile head, and flanges 28a and 28b provided on the upper and lower end surfaces thereof are attached to the lower surface 11a of the footing 11 and the upper end surface 24 of the pile head 14a. Abut and fix via an anchor bolt (not shown). As a result, the pile head 14a
And the isolator 28 installed between the footing 11 and
Is an existing building 10 while being elastically deformable in the horizontal direction.
Receives a vertical load of.

Next, as shown in FIG. 15, a strip steel 30a is fixed to the outer periphery of the steel rod damper 22b located on the lower surface 11a side of the footing 11 so as to surround the steel rod damper 22b from the outer peripheral side. Here, as shown in FIG. 15, the length between the strip 30a and the steel pipe 46, referred to as a flexible area L _3. Then, the temporary support that temporarily receives the vertical load of the existing building 10 is removed, and the vertical load of the existing building 10 is introduced into the support pile 14 via the isolator 28. Also,
The isolator 28 is also installed in the other support piles 14 by the above-described procedure, and the vertical load of the existing building 10 is introduced into the support piles 14 via the isolator 28.

As described above, in the second embodiment, the isolator 28 installed between the lower surface 11a of the footing 11 and the upper end surface of the pile head 14a and the lower surface 11 of the footing 11 are provided.
A seismic isolation device 48 is constituted by a plurality of steel rod dampers 44b extending downward from a and inserted into the steel pipe 46, and the seismic isolation device 48 exhibits the behavior shown in FIG. 16 according to the intensity of the earthquake. . In FIG. 16, the spare steel rod damper 44a is omitted.

That is, when an earthquake occurs, the isolator 28 is elastically deformed by a horizontal displacement δ ₃ as shown in FIG. 16, and the steel rod damper 44b can be moved in a state where its tip end slides inside the steel pipe 46. In the flexure region L ₃ , bending plastic deformation, that is, bending plastic deformation in both the positive and negative horizontal directions is caused as shown in FIG. Then, the steel rod damper 22b promptly attenuates the seismic force by absorbing hysteresis energy due to bending plastic deformation.

Therefore, in the second embodiment as well, as in the first embodiment, the period required for excavating the earth and sand to form the underground space 20 is short, and a large number of construction materials as in the prior art ( Since no jack, temporary support, steel column, etc.) are required, the construction period can be shortened. In addition, the pile head 14a directly below the footing 11
Concrete is crushed and removed to expose the pile rebar of the support pile 14, and the main bar extending downward from the lower surface 11a of the footing 11 is inserted into the steel pipe 46 to be used as the steel rod damper 44b and the footing 11 and The seismic isolation device 48 is configured by installing the isolator 28 that receives the vertical load of the existing building 10 so as to be elastically deformable in the horizontal direction between the pile head 14a and the isolator 28, and the hysteresis energy of the hysteresis energy due to the bending plastic deformation of the steel rod damper 44b is configured. Since the seismic force is quickly attenuated by absorption and the horizontal displacement of the existing building 10 is suppressed within the allowable range, it is possible to install the seismic isolation device 48 that is lower in cost than the related art. Thereby, the construction cost can be sufficiently reduced.

Further, the strip steel 30 arranged so as to surround the lower surface 11a side of the footing 11 of the plurality of steel rod dampers 44b.
a does not damage the concrete on the lower surface 11a of the footing 11 when the steel rod damper 44b is plastically deformed. Further, if the cut spare steel rod damper 44a is fixed again, the damping force of the steel rod damper 44b can be changed, and it can be used as a replacement steel rod damper.

The present embodiment has been described on the premise that the lower part of the frame 10a of the existing building 10 has a flat shape. However, for example, a lower part of the frame having an uneven bottom surface with a basement part provided in the soil is When it is formed, the ground immediately below the bottom of the unevenness of the lower part of the frame is cut off to form an underground space.

[0035]

As described above, according to the first aspect of the present invention,
The seismic isolation method of the existing building described forms a small underground space so that only the pile heads of the support piles are exposed, so the period required for excavation to form the underground space is short,
In addition, since a large number of construction materials are not required unlike the conventional seismic isolation construction method, it is possible to omit the period required for loading and unloading of materials. Therefore, the construction period can be significantly shortened as compared with the conventional seismic isolation method.

Further, by crushing the concrete of the pile head directly below the lower part of the skeleton and exposing a plurality of pile rebars fixed inside the concrete as a bare state, a vertical direction between the lower part of the skeleton and the pile head Since a predetermined number of these pile reinforcements are used as steel rod dampers that are plastically deformed by horizontal input when an earthquake occurs, it is possible to sufficiently reduce the construction cost. it can.

In the seismic isolation device for an existing building according to claim 2, the concrete of the pile heads of the support piles is crushed into an exposed state, and is not cut and is not cut between the lower part of the frame and the pile heads. A steel bar damper is used as the pile reinforcing bar extending in the direction, and a seismic isolation device is configured by installing a horizontally elastically deformable support device between the upper surface of the pile head and the lower surface of the lower frame. Therefore, the device can be simple. And
When an earthquake occurs, it is possible to quickly attenuate the seismic force by bending or tensile plastic deformation of the steel rod damper in the horizontal direction, and regulate the horizontal displacement of the existing building within an allowable range.

Further, if a predetermined number of spare steel rod dampers are fixed again, the damping force of the steel rod damper can be changed, and it can be used as a replacement steel rod damper. The seismic isolation device for an existing building according to claim 3 can obtain the effect according to claim 2, and
Even if the steel rod damper is plastically deformed when an earthquake occurs, the deformation preventing member is fixed to the lower side of the body of the steel rod damper and the pile head side, so that the lower portion of the body and the pile head are not damaged.

Further, the seismic isolation device for an existing building according to claim 4 can obtain the effect according to claim 3, and
Since the plastic deformation region of the steel rod damper is adjusted, it is possible to change the damping force of the steel rod damper, and it is also possible to change the horizontal displacement amount of the existing building. On the other hand, the seismic isolation device for an existing building according to claim 5 crushes the concrete of the pile head of the support pile to expose the pile rebar, and cuts all of the pile rebar on the pile head side, Insert the cutting ends of a predetermined number of pile rebars into multiple steel pipes fixed to the upper surface of the pile head, and insert the pile rebars with the cutting ends inside these steel pipes by inputting horizontally in the event of an earthquake. Since it is a steel rod damper that is plastically deformable in the horizontal direction and a bearing device is installed between the upper surface of the pile head and the lower surface of the lower part of the skeleton, the seismic isolation device is configured. It can be a device. Then, when an earthquake occurs, the seismic force can be quickly attenuated by the bending plastic deformation of the steel rod damper in the horizontal direction, and the horizontal displacement of the existing building can be regulated within the allowable range.

When the cut end of the spare steel rod damper is inserted into a plurality of steel pipes fixed to the upper surface of the pile head, the damping force of the steel rod damper can be changed and the replacement steel rod damper can be changed. Can also be used as In addition, the seismic isolation device for an existing building according to claim 6 can obtain the effect according to claim 5, and even if the steel rod damper is plastically deformed when an earthquake occurs, the steel rod damper is deformed to the lower side of the frame. Since the prevention member is fixed, the lower part of the body is not damaged.

Further, the seismic isolation device for an existing building according to claim 7 can obtain the effect according to claim 6, and the plastic deformation region of the steel rod damper between the steel pipe and the deformation preventing member is adjusted. Therefore, it is possible to change the damping force of the steel rod damper, and it is also possible to change the horizontal displacement amount of the existing building.

[Brief description of the drawings]

FIG. 1 is a diagram showing an existing building in which a vertical load is supported by a plurality of reinforced concrete support piles.

FIG. 2 is a diagram showing a state in which an underground space is formed by cutting off a lower part of a skeleton of an existing building so that a pile head of each support pile is exposed.

FIG. 3 (a) is a side view showing a state in which concrete on the pile head is crushed and removed to expose the pile rebar, and FIG.
FIG. 3A is a view taken along the line III-III in FIG.

FIG. 4A is a side view showing a steel rod damper and a spare steel rod damper in the first embodiment, and FIG. 4B is a side view of FIG.
It is an IV-IV line arrow view.

FIG. 5A is a side view showing a state in which a bearing device is installed in the first embodiment, and FIG. 5B is a V-of FIG.
FIG.

FIG. 6A is a side view showing a state where a steel strip is fixed to a steel rod damper in the first embodiment, and FIG.
It is a VI-VI line arrow line view of (a).

FIG. 7 is a diagram showing the behavior of the seismic isolation device of the first embodiment when a small-scale earthquake occurs.

FIG. 8 is a graph showing the characteristics of the steel rod damper of the first embodiment when a small-scale earthquake occurs.

FIG. 9 is a diagram showing the behavior of the seismic isolation device of the first embodiment when a large-scale earthquake occurs.

FIG. 10 is a graph showing characteristics of the steel rod damper of the first embodiment when a large-scale earthquake occurs.

FIG. 11 is a side view showing a modified example of the first embodiment.

FIG. 12 is a side view showing a state in which a lower end portion of a pile reinforcing bar exposed by crushing and removing concrete in the second embodiment is cut.

FIG. 13A is a side view showing a steel rod damper in which a tip portion is inserted into a steel pipe fixed to an upper surface of a pile head in the second embodiment, and FIG. 13B is a XII-XII portion of FIG. FIG.

FIG. 14A is a side view showing a state in which a bearing device is installed in the second embodiment, and FIG. 14B is a XI of FIG.
It is a V-XIV line arrow line view.

FIG. 15 is a side view showing a state where a steel strip is fixed to a steel rod damper in the second embodiment.

FIG. 16 is a diagram showing the behavior of the seismic isolation device according to the second embodiment when an earthquake occurs.

[Explanation of symbols]

 10 Existing Building 11 Footing (Bottom of Body) 14 Support Pile 14a Pile Head 20 Underground Space 22 Pile Reinforcing Bar 22a, 44a Spare Steel Bar Damper 22b, 44b Steel Bar Damper 28 Isolator (Bearing Device) 30a, 30b Strip Steel (Deformation Prevention Member) ) 36b Spiral rebar (deformation preventing member) 32, 48 Seismic isolation device 46 Steel pipe

Claims (7)

[Claims] 1. An underground space is formed by cutting the ground immediately below the lower part of the frame along the lower part of the frame of an existing building, and the underground space is made of reinforced concrete and is buried in the soil from the lower part of the frame. A step of exposing only the pile heads of the support piles, a step of standingly installing a temporary support in the underground space, and causing the temporary support to bear the vertical load of the existing building that the support piles bear. , Crushing the concrete of the pile head directly below the skeleton lower part and extending in the vertical direction between the skeleton lower part and the pile head part as a bare state in which a plurality of pile reinforcing bars anchored inside this concrete are exposed And a step of using a predetermined number of pile rebars among a plurality of bare bar reinforcements as a steel rod damper that plastically deforms due to horizontal input when an earthquake occurs, and Between the surfaces and the lower surface of the skeleton lower releases the step of installing the elastically deformable support device in the horizontal direction, the support of the existing building by the temporary receiving support,
A step of introducing a vertical load of the existing building into the support pile via the bearing device, and a method for seismic isolation of the existing building. 2. A seismic isolation device in which a support pile made of reinforced concrete is buried in the soil from the lower part of the skeleton of an existing building, and is interposed between the lower part of the skeleton and the pile head of the support pile. Crush the concrete of the pile head of the support pile to leave the pile rebar exposed, and cut a predetermined number of these pile rebars between the lower part of the frame and the support pile as a spare steel rod damper, without cutting. The remaining pile reinforcing bars extending between the lower part of the frame and the pile head are steel rod dampers that are plastically deformed by an input in the horizontal direction when an earthquake occurs, and the upper surface of the pile head and the lower part of the frame. A seismic isolation device for an existing building, in which a supporting device that is elastically deformable in the horizontal direction is installed between the lower surface of the building and the lower surface of the building. 3. The seismic isolation device for an existing building according to claim 2, wherein the lower side of the body of the steel rod damper and the head side of the pile are fixed by a deformation preventing member. 4. The vertical width of the deformation preventing member fixed to the lower body side and the pile head side of the steel rod damper is changed so that a plastic deformation region of the steel rod damper between the deformation preventing members is changed. The seismic isolation device for an existing building according to claim 3, wherein the seismic isolation device is adjusted. 5. A seismic isolation device in which a support pile made of reinforced concrete is buried in the soil from the lower part of the skeleton of an existing building, and is interposed between the lower part of the skeleton and the pile head of the support pile, The concrete of the pile head of the support pile is crushed and the pile rebar is exposed, and all of these pile rebars are cut on the pile head side, and the cut end of a predetermined number of pile rebars is placed on the upper surface of the pile head. Inserted inside a plurality of steel pipes fixed to the steel pipes, the pile rebars with cut ends inserted inside these steel pipes are used as steel rod dampers that are plastically deformed by horizontal input when an earthquake occurs,
The existing pile reinforcing bars are used as spare steel rod dampers, and a horizontally elastically deformable support device is installed between the upper surface of the pile head and the lower surface of the lower frame. Building seismic isolation device. 6. The seismic isolation device for an existing building according to claim 5, wherein the lower side of the body of the steel rod damper is fixed by a deformation preventing member. 7. The vertical width of a deformation preventing member fixed to the lower side of the body of the steel rod damper is changed, and a plastic deformation region of the steel rod damper between the deformation preventing member and the steel pipe is adjusted. The seismic isolation device for an existing building according to claim 6.