JP2016079754A - Method for constructing base isolation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for constructing a base isolation structure capable of curbing a reduction in aseismic performance even when skeleton concrete shrinks.SOLUTION: In a building 1 which has a base isolation structure, an upper foundation beam 12 is supported by a base isolation device 20 installed on a mat slab 11. A method for constructing the building 1 comprises: steps S3 to S5 to construct the upper foundation beam 12 with a length longer than a design length in anticipation of shrinkage of concrete thereof and to temporarily support the upper foundation beam 12 so that the same can slide on the mat slab 11; and step S6 to install laminated rubber 201 between the upper foundation beam 12 and the mat slab 11 after the lapse of predetermined time and to support the upper foundation beam 12 with the base isolation device 20 including the laminated rubber 201.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for constructing a building having a seismic isolation structure, for example.

  Traditionally, there are seismically isolated buildings. This building includes, for example, a lower housing such as a foundation, a plurality of seismic isolation devices installed on the lower housing, and an upper housing provided on these seismic isolation devices. This seismic isolation device has an isolator and a damper. Of these, the isolator supports the load of the upper housing and moves the upper structure slowly in the horizontal direction during an earthquake. The types of isolators include laminated rubber, sliding bearings and rolling bearings.

  By the way, when the upper frame is made of reinforced concrete and is long in the specified direction, after the construction of the upper frame is completed, the frame concrete shrinks due to hydration reaction and drying, and the amount of drying shrinkage is only 400 to 600 μm in several years even with the amount of drying shrinkage alone. In a building with a side of 100 m, the calculation is reduced by 4 to 6 cm. In buildings that are not seismically isolated, the foundation is constrained by the ground, so the entire building does not shrink so much. However, in base-isolated buildings, the upper housing is placed on the lower housing via elastically deformable elastic bodies, horizontally displaceable sliding bearings, rolling bearings, etc. Because of the large difference, the amount of contraction between the upper and lower housings will vary greatly over time. When contraction progresses, the outer periphery of the upper housing may move inward. Then, in the vicinity of the outer periphery of a building with a long side, the upper part of the laminated rubber is pulled by the concrete and sheared horizontally, which is not only bad in appearance, but also remains after the initial contraction has subsided. As a result, the seismic isolation performance of the building may be reduced. In addition, the column core of the upper frame and the pile core of the lower frame may be displaced, and an excessive force exceeding the design assumption may be applied to the pile and the foundation.

In order to solve this problem, for example, before constructing the upper frame, a method has been proposed in which the upper part of the seismic isolation device is displaced by the amount of shrinkage of the concrete at the outer periphery of the building (Patent Document 1). reference).
Specifically, the upper part of the seismic isolation device is displaced in advance in the direction opposite to the direction displaced by concrete contraction by an amount equal to the amount of concrete shrinkage that occurs after construction of the upper frame, and this displacement is performed by the mounting member. Is held. Then, after the upper casing is constructed, this holding state is released. Therefore, when the frame concrete contracts, the upper part of the seismic isolation device returns to its original proper position.

JP 2006-97325 A

However, the method disclosed in Patent Document 1 has the following problems.
Actually, since the concrete of the upper frame is restrained by the exterior material and the interior material, it is difficult to accurately predict the shrinkage amount of the concrete.
Moreover, in order to displace the upper part of a seismic isolation apparatus to a horizontal direction, it is necessary to apply a quite big force. In addition, when the seismic isolation device is displaced in the horizontal direction in a state where no vertical load is applied to the seismic isolation device, there is a high possibility that the upper surface of the elastic member is inclined.
For this reason, there is a possibility that the seismic isolation performance may be reduced due to the shrinkage of the concrete frame.

  An object of this invention is to provide the construction method of the seismic isolation structure which can suppress the fall of seismic isolation performance, even if a frame concrete shrink | contracts.

  The construction method of the seismic isolation structure according to claim 1 is a method of constructing an upper housing (for example, a seismic isolation device 20 described later) provided on a lower housing (for example, mat slab 11 described later). , A method for constructing a base-isolated structure that supports an upper base beam 12 described later, and a step of temporarily supporting at least the outermost part of the upper casing from the lower casing (for example, described later) Steps S <b> 3 to S <b> 5) and a step of attaching a laminated rubber to the temporarily supported portion or the vicinity thereof after a predetermined period of time and supporting the upper housing by a seismic isolation device including the laminated rubber (for example, steps described later) S6).

  Here, the predetermined period is a period until the volume change (shrinkage) of the concrete substantially converges. The shrinkage due to the hydration reaction (self-shrinkage), which accounts for most of the volume change of the concrete, and the water in the concrete There are two types of shrinkage: shrinkage due to dissipation in the air (dry shrinkage). Since these shrinkage converges within a few months after placing the concrete, it is desirable that the temporary support period be longer than a few months. However, since it is better to be short in relation to other construction processes, at least several hours after placing the concrete where initial shrinkage is moderate are necessary.

  The construction method of the seismic isolation structure according to claim 2 is such that the upper housing (for example, the seismic isolation device 20 described later) provided on the lower housing (for example, mat slab 11 described later) is used. , A method for constructing a base-isolated structure for supporting an upper foundation beam 12), which will be described later, in consideration of the amount of shrinkage of the concrete of the upper frame, and constructing the upper frame longer than the design dimensions, A step of temporarily supporting the upper housing from the lower housing (for example, steps S3 to S5 described later), and a step of attaching the seismic isolation device after a predetermined period of time and supporting the upper housing by the seismic isolation device (for example, Step S6) described below.

According to the present invention, the upper casing is constructed larger than the designed dimensions, and the seismic isolation device is attached after a predetermined period of time has elapsed and the concrete of the upper casing has contracted to some extent.
Therefore, even if the concrete of the upper frame contracts, since the seismic isolation device is attached after the concrete contraction, deformation of the seismic isolation device is suppressed. Therefore, unlike the conventional case, it is not necessary to accurately predict the amount of shrinkage of the concrete, and it is not necessary to deform the seismic isolation device in advance.

  In the method of constructing the seismic isolation structure according to claim 2, in the step of temporarily supporting the upper casing from the lower casing, provisional support columns (for example, temporary support columns 30 described later) are provided on the lower case. The temporary support column temporarily supports the upper case, and a slip plate (for example, a later-described slide plate 40) is interposed between the temporary support column and the upper case or the lower case. Features.

  According to the present invention, the upper casing is temporarily supported by the temporary support column provided on the lower frame, and the sliding plate is interposed between the temporary support column and the upper or lower frame. Therefore, even after the upper casing is temporarily supported, even if the concrete of the upper casing contracts and the upper casing moves horizontally, the temporary support column slides on the sliding plate, so that the stability of the upper casing can be maintained. it can.

  According to the present invention, even if the concrete of the upper frame contracts, the seismic isolation device is attached after contraction, so that deformation of the seismic isolation device is suppressed. Therefore, unlike the conventional case, it is not necessary to accurately predict the amount of shrinkage of the concrete, and it is not necessary to deform the seismic isolation device in advance.

It is sectional drawing of the foundation part of the building constructed | assembled by the construction method of the seismic isolation structure which concerns on 1st Embodiment of this invention. It is a flowchart of the procedure which builds a building with the construction method of the seismic isolation structure which concerns on the said embodiment. It is FIG. (1) explaining the procedure which builds the building which concerns on the said embodiment. It is FIG. (2) explaining the procedure which builds the building which concerns on the said embodiment. It is a figure (the 3) explaining the procedure which builds the building which concerns on the said embodiment. It is sectional drawing of the building constructed | assembled by the construction method of the seismic isolation structure which concerns on 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the procedure which builds the building which concerns on the said embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[First Embodiment]
As shown in FIG. 1, the building 1 is a seismic isolation structure and has a foundation 2 constructed on the ground 3. The foundation 2 is a pile foundation, and includes a pile 10, a mat slab 11 as a lower housing provided on the pile 10, a seismic isolation device 20 provided on the mat slab 11, and a seismic isolation device 20. The upper foundation beam 12 as an upper frame provided on the upper foundation beam 12 and the column 13 provided on the upper foundation beam 12 are provided.
That is, in the building 1, the upper foundation beam 12 is supported by the seismic isolation device 20 provided on the mat slab 11. The seismic isolation device 20 is provided in the outermost part of the building 1.

An installation space 21 for installing the seismic isolation device 20 is formed between the mat slab 11 of the foundation 2 and the upper foundation beam 12.
A lower base isolation base 23 made of reinforced concrete is provided immediately below the column 13 and on the upper surface of the mat slab 11, and a lower base plate 231 is driven into the upper surface of the lower base isolation base 23.
An upper base isolation base 24 made of reinforced concrete is provided directly below the column 13 and on the lower surface of the upper base beam 12, and an upper base plate 241 is driven into the lower surface of the upper base isolation base 24.

The seismic isolation device 20 is provided between the lower base isolation base 23 and the upper base isolation base 24.
The seismic isolation device 20 includes a laminated rubber 201, a lower flange 202 provided under the laminated rubber 201, and an upper flange 203 provided on the laminated rubber 201.

The laminated rubber 201 is obtained by alternately laminating steel plates and rubber.
The lower flange 202 is bolted to the lower base plate 231, and the upper flange 203 is bolted to the upper base plate 241.
The above seismic isolation device 20 takes the reaction force on the lower base isolation base 23 and supports the upper base isolation base 24 from below, and the laminated rubber 201 is deformed to deform the upper base isolation base 24 in the horizontal direction. It is movable.

As shown in the flowchart of FIG. 2, in step S1, the ground 3 for constructing the foundation 2 is excavated.
As shown in FIG. 3, a pile 10 is constructed on the ground 3 as necessary, and then the ground 3 is excavated to a depth that becomes the bottom surface of the mat slab 11 to form an excavation space.

In step S <b> 2, the mat slab 11 is constructed in the excavation space, and the temporary support column 30 is slidably installed on the mat slab 11.
As shown in FIG. 3, the mat slab 11 is constructed by placing the discarded concrete 25 on the bottom surface of the excavation space and placing the concrete on the discarded concrete 25 and placing the concrete.

  Next, a slip plate 40 is provided on the mat slab 11 and in the vicinity of the periphery of the portion for constructing the lower seismic isolation foundation 23, and the temporary support column 30 is installed on the slip plate 40.

The provisional support column 30 includes a lower column 31 provided on the mat slab 11, a jack 32 provided on the lower column 31, and a jack 32 provided on the lower surface of the upper foundation beam 12. An upper column 33 to be joined. The jack 32 makes the lower column 31 and the upper column 33 approach or separate from each other.
The sliding plate 40 is interposed between the lower column 31 of the temporary support column 30 and the mat slab 11, and a nylon sheet, for example, is attached to the upper surface of the sliding plate 40.

In step S3, the upper foundation beam 12 is constructed.
As shown in FIG. 3, the upper foundation beam 12 is constructed on the temporary support column 30. The upper foundation beam 12 is constructed to be longer than the design dimensions by calculating in advance the amount of shrinkage of the concrete of the upper foundation beam 12 and considering the calculated amount of shrinkage. Specifically, in the present embodiment, the upper foundation beam 12 moves in the left direction in FIG. 3 due to the contraction of the concrete of the upper foundation beam 12, so that the movement is expected and the length becomes longer in the right direction in FIG. doing.

  At this time, the upper base beam 12 is temporarily supported by driving the jack 32 of the temporary support column 30 in a direction in which the lower column 31 and the upper column 33 are separated from each other, thereby applying a reaction force to the mat slab 11. Thereby, the load of the building 1 is transmitted to the pile 10 via the temporary support column 30 and the mat slab 11, and the upper foundation beam 12 is temporarily supported by the temporary support column 30.

In step S4, the bars 13, the lower base isolation base 23, and the upper base isolation base 24 are arranged.
As shown in FIG. 3, the bar 13 </ b> A of the column 13 on the upper foundation beam 12 is arranged, and the reinforcing bar 23 </ b> A of the lower seismic isolation foundation 23 is arranged on the upper surface of the mat slab 11. Reinforcing bars 24A of the upper seismic isolation base 24 are arranged on the lower surface.
At this time, since the upper foundation beam 12 is constructed longer than the designed dimension, the central axis C2 of the upper base isolation base 24 is shifted from the central axis C1 of the lower base isolation base 23.

In step S <b> 5, the pillar 13 is constructed, the upper seismic isolation foundation 24 is constructed, and the seismic isolation device 20 is attached to the upper seismic isolation foundation 24.
As shown in FIG. 4, the formwork of the pillar 13 is built, concrete is laid, and the pillar 13 is constructed. Also. The upper base plate 241 is attached to the reinforcing bars 24A of the upper seismic isolation foundation 24, a formwork is built, concrete is placed, and the upper seismic isolation foundation 24 is constructed. Further, the upper flange 203 of the seismic isolation device 20 is bolted to the upper base plate 241 of the upper seismic isolation base 24 to suspend and support the seismic isolation device 20 from the upper base isolation base 24.

In step S <b> 6, after a predetermined period, that is, a period until the contraction of concrete substantially converges, the lower base isolation base 23 is constructed, and the base isolation device is attached to the lower base isolation base 23.
When the predetermined period has elapsed, due to the contraction of the concrete of the upper foundation beam 12, the upper foundation beam 12 moves to the left in FIG. 5, and the central axis C <b> 2 of the upper base isolation base 24 changes to the central axis C <b> 1 of the lower base isolation base 23. It almost agrees. At this time, since the upper surface of the temporary support column 30 is joined to the upper foundation beam 12, the temporary support column 30 slides on the slide plate 40.

  Therefore, the lower base plate 231 of the lower base isolation base 23 is bolted to the lower flange 202 of the base isolation device 20 already fixed to the upper base isolation base 24, and in this state, the form of the reinforcing bar 23A of the lower base isolation base 23 Is built and concrete is laid, and the lower seismic isolation base 23 is constructed. Thereby, the laminated rubber 201 is attached in the vicinity of the place temporarily supported by the temporary support column 30, and the lower seismic isolation base 23 and the upper seismic isolation foundation 24 are connected via the laminated rubber 201. The upper foundation beam 12 is supported by the seismic isolation device 20 including the rubber 201.

In step S7, the temporary support column 30 is removed.
First, the temporary support of the foundation 2 is released by driving the jack 32 of the temporary support column 30 to bring the lower column 31 and the upper column 33 closer to each other.
Next, the temporary support column 30 is removed. Thereby, the upper foundation beam 12 is supported by the seismic isolation device 20.

According to this embodiment, there are the following effects.
(1) The upper foundation beam 12 is constructed to be larger than the design dimension in consideration of the shrinkage amount of the concrete of the upper foundation beam 12. And after the predetermined period passes and the concrete of the upper foundation beam 12 contracts to some extent, the seismic isolation device 20 is attached.
Therefore, even if the concrete of the upper foundation beam 12 contracts, the seismic isolation device 20 is attached after the concrete contraction, so that deformation of the seismic isolation device 20 is suppressed. Therefore, unlike the prior art, there is no need to accurately predict the amount of shrinkage of the concrete or to deform the seismic isolation device in advance.

  (2) The upper foundation beam 12 was temporarily supported by a temporary support column 30 provided on the mat slab 11, and a slip plate 40 was interposed between the temporary support column 30 and the mat slab 11. Therefore, after temporarily supporting the upper foundation beam 12, even if the concrete of the upper foundation beam 12 contracts and the upper foundation beam 12 moves horizontally, the temporary support column 30 slides on the sliding plate 40. The stability of the upper foundation beam 12 can be maintained.

[Second Embodiment]
FIG. 6 is a schematic view of a seismic isolation structure according to the second embodiment of the present invention.
In this embodiment, the point which applied this invention to the outer peripheral part of the building 1A differs from 1st Embodiment, and the other structure is the same as that of 1st Embodiment.

The building 1A includes a mat slab 2 as a lower casing, a plurality of seismic isolation devices 20A and 20B provided on the mat slab 2, and an upper casing provided on the seismic isolation devices 20A and 20B. And a building body 4.
The building body 4 extends in a predetermined direction, that is, in the left-right direction in FIG. 6, and has a ramen structure composed of a reinforced concrete column member and a beam member.

The seismic isolation devices 20A and 20B are arranged along the left-right direction in FIG. Of these seismic isolation devices 20A and 20B, the seismic isolation device 20A is arranged on the center side of the building 1A in plan view, and the outer peripheral portion on the short side of the building 1A in plan view, that is, the outermost portion, A seismic isolation device 20B is arranged.
The seismic isolation devices 20A and 20B each have the same structure as the seismic isolation device 20 of the first embodiment.

The above building 1A is constructed in the following procedure.
First, as shown in FIG. 7, the ground 3 is excavated to construct the mat slab 2, the seismic isolation device 20A and the temporary support post 30 are installed on the mat slab 2, and the seismic isolation device 20A and the temporary reception are installed. The building body 4 is constructed on the column 30.
Specifically, the seismic isolation device 20A is completed on the center side of the building 1A, and the building body 4 is supported by the seismic isolation device 20A. On the other hand, on the outer peripheral side of the building 1A, steps S1 to S5 of the first embodiment are executed, but without performing steps S6 and S7 of the first embodiment, the seismic isolation device 20B is in an incomplete state, The building body 4 is supported by the temporary support columns 30.

Next, after the lapse of a predetermined period, the seismic isolation device 20B is completed at the outer periphery of the building 1A.
When the predetermined period elapses, the frame concrete contracts and the building body 4 is displaced in the direction of the arrow in FIG. Since this displacement becomes larger as it gets closer to the outer periphery of the building 1A, the temporary support column 30 slides on the slip plate 40 in the outer periphery of the building 1A.
Therefore, steps S6 and S7 of the first embodiment are executed to complete the seismic isolation device 20B.

  According to the present embodiment, there are the same effects as the above (1) and (2).

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the above-described embodiments, when the upper foundation beam 12 is constructed, the concrete shrinkage amount of the upper foundation beam 12 is calculated in advance, and the foundation beam 12 is designed in consideration of the calculated shrinkage amount. However, the present invention is not limited to this, and the seismic isolation device may be attached after the concrete contracts without expecting the contraction amount of the concrete of the upper foundation beam 12.

1, 1A ... Building (Seismic isolation structure)
2 ... Foundation 3 ... Ground 4 ... Building body (upper frame)
10 ... Pile 11 ... Mat slab (lower frame)
12 ... Upper foundation beam (upper frame)
DESCRIPTION OF SYMBOLS 13 ... Pillar 13A ... Column reinforcement 20, 20A, 20B ... Seismic isolation device 21 ... Installation space 23 ... Lower seismic isolation base 23A ... Reinforcement 24 ... Upper seismic isolation base 24A ... Reinforcement 25 ... Discard concrete 30 ... Temporary support post 31 ... Lower Support column 32 ... Jack 33 ... Upper support column 40 ... Sliding plate 201 ... Laminated rubber 202 ... Lower flange 203 ... Upper flange 231 ... Lower base plate 241 ... Upper base plate

Claims (3)

A method of constructing a seismic isolation structure that supports an upper chassis by a seismic isolation device provided on the lower chassis,
Temporarily supporting at least the outermost part of the upper housing from the lower housing so as to be slidable;
Attaching a laminated rubber at or near the temporarily supported portion after a predetermined period of time, and supporting the upper housing with a seismic isolation device including the laminated rubber. How to build. A method of constructing a seismic isolation structure that supports an upper chassis by a seismic isolation device provided on the lower chassis,
Expecting the amount of shrinkage of the concrete of the upper housing, constructing the upper housing longer than the design dimensions, and temporarily supporting the upper housing from the lower housing;
And a step of attaching the seismic isolation device after a predetermined period of time and supporting the upper housing by the seismic isolation device.   In the step of temporarily supporting the upper housing from the lower housing, provisional support posts are provided on the lower housing, and the upper housing is temporarily supported by the temporary support posts, and the temporary support posts and the upper housing or The construction method of the seismic isolation structure according to claim 1 or 2, wherein a slip plate is interposed between the lower casing and the lower casing.

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