Seismic isolation building

Abstract

The invention provides a base-isolated building with multiple independent foundations placed within a base-isolation pit enclosed by a retaining wall. [Solution] A base-isolated building equipped with columns is provided with a base isolation pit EP1. Independent foundations 21 supporting the columns are provided within this base isolation pit EP1. Retaining wall members 40, which constitute part of the retaining wall used to surround the base isolation pit EP1, are placed between the independent foundations 21. The retaining wall member 40 comprises a base plate portion 41 extending to the opposite side of the base isolation pit EP1 and a wall portion 45 extending upward.

Description

【Technical Field】 【0001】 The present disclosure relates to a seismic isolation building provided with a seismic isolation device. 【Background Art】 【0002】 Conventionally, there has been known a seismic isolation building in which the shaking of the upper structure of a building is reduced by disposing a seismic isolation device such as laminated rubber in the lower structure of the building. In this seismic isolation building, the seismic isolation device may be disposed in a seismic isolation pit provided at a low position from the ground. For this reason, the periphery of the seismic isolation pit is surrounded by a retaining wall that supports the earth pressure. In this case, in the seismic isolation building, it is necessary to provide a seismic isolation clearance for avoiding collision during an earthquake between the upper structure and structures such as the surrounding retaining wall (see, for example, Patent Document 1). This document shows a seismic isolation structure in which a retaining wall is constructed around a seismic isolation building in which a seismic isolation device is disposed in a seismic isolation pit. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2022-007100 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 As described in Patent Document 1, the retaining wall is provided connected to the foundation. Usually, since a plurality of foundations of a building are connected by a foundation beam, the retaining wall can be erected against the earth pressure by the foundation, the foundation beam, etc. However, when constructing a seismic isolation building on hard ground, independent foundations without a foundation beam connecting the foundations may be used. When constructing a seismic isolation building on this independent foundation, it has not been done to dispose it in a seismic isolation pit dug from the ground. 【Means for Solving the Problems】 【0005】 A base-isolated building that solves the above problems is a base-isolated building equipped with independent foundations on which base isolation devices are installed, wherein the independent foundations are located within a base isolation pit surrounded by retaining walls. [Effects of the Invention] 【0006】 According to this disclosure, a base-isolated building can be constructed by arranging multiple independent foundations within a base-isolation pit surrounded by a retaining wall. [Brief explanation of the drawing] 【0007】 [Figure 1] This is a plan view showing the foundation and retaining wall members in the seismic isolation layer of a seismically isolated building in an embodiment. [Figure 2] This is a plan view of the main part shown in Figure 1, enlarged. [Figure 3] This is a schematic diagram illustrating the main components of the embodiment. [Figure 4] This is a cross-sectional view in the direction of line 4-4 in Figure 2. [Figure 5] This is a cross-sectional view in the direction of line 5-5 in Figure 2. [Figure 6] This is a cross-sectional view of the main part of the modified example. [Modes for carrying out the invention] 【0008】 Below, an embodiment of a seismically isolated building will be described using Figures 1 to 5. Figure 1 is a plan view of the seismic isolation pit EP1 of the seismically isolated building 10. Figure 2 is a plan view of the main part of Figure 1, and Figure 3 is a schematic diagram of the main part of Figure 1. Figures 4 and 5 are cross-sectional views in the direction of lines 4-4 and 5-5 in Figure 2. 【0009】 As shown in Figure 1, the base-isolated building 10 is equipped with multiple spaced-apart independent foundations 11, 21. The independent foundations 11, 21 are located within the base isolation pit EP1. The independent foundations 11, 21 are made of reinforced concrete and support the columns 29 of the base-isolated building 10. 【0010】 The isolated foundations 21 are positioned around the perimeter of the base-isolated building 10, while the isolated foundations 11 are positioned further inward than the isolated foundations 21. The isolated foundation 11, located inside the isolated foundation 21, comprises a lower foundation 13 and an upper foundation 14 above it. A seismic isolation device (not shown) is positioned between the lower foundation 13 and the upper foundation 14 of the isolated foundation 11. 【0011】 As shown in Figures 2 and 3, retaining wall members 40 are positioned between a plurality of spaced-apart independent foundations 21 around the perimeter of the base-isolated building 10. In this embodiment, the independent foundations 21 and retaining wall members 40 are arranged alternately to surround the perimeter of the base-isolated building 10. 【0012】 As shown in Figures 4 and 5, beams B1 and B2, made of H-shaped steel, are arranged to intersect with the upper surface of the upper foundation 27, making them flush with it. The floor slab 16 of the first floor of the base-isolated building 10 is constructed on top of beams B1 and B2. This floor slab 16 is integrated with the covering portion 17 and the wall portion 18 of the base-isolated building 10. The covering portion 17 closes the area above the base isolation clearance S1 of the base isolation pit EP1, which will be described later. Furthermore, as shown in Figure 5, a floor slab 19 made of reinforced concrete may be placed at the bottom of the seismic isolation pit EP1, which is formed at a position lower than the ground level G1. 【0013】 (Detailed configuration of the 21 independent foundations) As shown in Figure 4, the isolated foundations 21 arranged around the perimeter of the base-isolated building 10 have a lower foundation 23 and an upper foundation 27, similar to the isolated foundations 11. A base isolation device 25 is positioned between the lower foundation 23 and the upper foundation 27. For example, a base isolation rubber is used as the base isolation device 25. When an earthquake occurs, the upper part of the base isolation device 25 shifts left and right relative to the lower part. For this reason, a base isolation clearance S1 is provided between the base isolation pit EP1 and the foundation wall 24 to allow the base isolation device 25 to move. The lower ends of the columns 29 are embedded in the isolated foundations 21. 【0014】 At the outer peripheral end of the lower foundation 23 of the independent foundation 21, a foundation wall portion 24 extending upward is integrally formed. The lower foundation 23 is composed of reinforcing bars 23R1 arranged in a grid pattern in the horizontal direction and reinforcing bars 23R2 arranged in the vertical direction, which are embedded in the concrete C1. The portion of the reinforcing bar 23R1 extending in the extending direction of the foundation wall portion 24 has its end inserted into the foundation wall portion 24. 【0015】 The foundation wall portion 24 constitutes a part of the retaining wall surrounding the outer periphery of the seismic isolation pit EP1. In this foundation wall portion 24, two reinforcing bars 24R1 and 24R2 extending vertically and arranged on the outer and inner sides, and a plurality of spaced reinforcing bars R1 extending in a direction perpendicular to the plane of the drawing are embedded in the concrete C1. 【0016】 (Detailed configuration of the retaining wall member 40) As shown in FIG. 5, the retaining wall member 40 arranged between the independent foundations 21 is composed of reinforced concrete with an L-shaped cross section, and includes a bottom plate portion 41 and a wall portion 45. The wall portion 45 extends upward and is integrally formed at one end of the bottom plate portion 41. The bottom plate portion 41 is arranged to extend in the horizontal direction on the side opposite to the seismic isolation pit EP1 of the seismic isolation building 10. This bottom plate portion 41 is placed on the ground improvement portion Gi1. The bottom plate portion 41 has lattice-shaped upper-stage reinforcing bars 41a and lower-stage reinforcing bars 41b. The ends of the upper-stage reinforcing bars 41a and lower-stage reinforcing bars 41b on the side opposite to the wall portion 45 are embedded in the concrete C1 in a state where the lower or upper part is bent respectively. 【0017】 The wall portion 45 has substantially the same thickness as the foundation wall portion 24 of the independent foundation 21 and is arranged side by side in a straight line. This wall portion 45, like the foundation wall portion 24, constitutes a part of the retaining wall surrounding the outer periphery of the seismic isolation pit EP1. 【0018】 The wall portion 45 is formed by embedding a plurality of reinforcing bars 45R1, 45R2, 45R3, R1 in concrete C1. The plurality of reinforcing bars 45R1 extend vertically in a spaced-apart state in a direction orthogonal to the plane of the paper and are disposed outside the seismic isolation pit EP1. The plurality of reinforcing bars 45R2 extend vertically in a spaced-apart state in a direction orthogonal to the plane of the paper and are disposed on the side of the seismic isolation pit EP1. The plurality of reinforcing bars 45R3 have an inverted U shape and are disposed at the upper end portion of the wall portion 45. The reinforcing bar R1 is a reinforcing bar that extends in a direction perpendicular to the plane of the paper and is also embedded in the foundation wall portion 24 of the independent foundation 21, and is disposed so as to penetrate through the independent foundation 21 and the retaining wall member 40. 【0019】 (Construction method of the seismic isolation building 10) Next, the construction method of the seismic isolation building 10 described above will be explained. In this embodiment, the seismic isolation pit EP1 and its surroundings are excavated. Then, by injecting a cement-based hardening agent, a ground improvement portion Gi1 is formed as a portion for placing the bottom plate portion 41 of the retaining wall member 40. Thereafter, the reinforcing bars 45R1, 45R2, 45R3, R1 of the retaining wall member 40 are disposed on the ground improvement portion Gi1, and a concrete form corresponding to the shape of the retaining wall member 40 is disposed. Also, the lower foundation 23 of the independent foundation 21, the upper reinforcing bars 41a and the lower reinforcing bars 41b of the foundation wall portion 24, and the reinforcing bar R1 are disposed, and a concrete form corresponding to the shapes of the lower foundation 23 and the foundation wall portion 24 is disposed. Then, after injecting concrete into the concrete form, curing is performed, and the concrete form is removed to form the retaining wall member 40, the lower foundation 23 of the independent foundation 21, and the foundation wall portion 24. 【0020】 Then, the retaining wall member 40 is erected by placing soil SO1 on the bottom plate portion 41 of the retaining wall member 40. Thereafter, the seismic isolation device 25 is disposed on the lower foundation 23. Then, the upper foundation 27 is formed of reinforced concrete on the seismic isolation device 25. In this case, the column 29 is erected by embedding the lower end portion of the column 29 in the upper foundation 27. Furthermore, after arranging beams B1 and B2, the floor slab 16, the covering section 17, and the wall section 18 of the base-isolated building 10 are integrated and formed using reinforced concrete. 【0021】 (Effect of the embodiment) Between multiple spaced-apart independent foundations 21, a retaining wall member 40 having a base plate portion 41 is positioned on the outside of the seismic isolation building 10 (seismic isolation pit EP1). The foundation wall portions 24 of the independent foundations 21 and the wall portions 45 of the retaining wall member 40 then form a retaining wall surrounding the seismic isolation pit EP1. 【0022】 (Effects of the embodiment) (1) In this embodiment, the seismically isolated building 10 is equipped with a seismic isolation pit EP1 surrounded by retaining wall members 40. An independent foundation 21 is provided inside the seismic isolation pit EP1, which supports columns 29 and is equipped with seismic isolation devices 25. This makes it possible to place the independent foundation 21 inside the seismic isolation pit EP1 surrounded by retaining walls. 【0023】 (2) In this embodiment, the independent foundations 21 without foundation beams are positioned on the outer perimeter of the seismic isolation pit EP1. Furthermore, retaining wall members 40 having a base plate portion 41 and wall portions 45 are positioned between the multiple spaced-apart independent foundations 21. This allows the seismic isolation pit EP1 to be surrounded using the independent foundations 21 and the retaining wall members 40. In this case, the base plate portion 41 of the retaining wall member 40 is positioned on the outside of the seismic isolation building 10, and soil SO1 is placed on it, so even if the base plate portion 41 of the retaining wall member 40 is shortened, the retaining wall member 40 can be installed stably. 【0024】 (3) In this embodiment, an upward-extending foundation wall portion 24 is formed on the independent foundation 21. This foundation wall portion 24 is arranged in a straight line that is continuous with the wall portion 45 of the retaining wall member 40. As a result, a retaining wall surrounding the seismic isolation pit EP1 can be constructed by the foundation wall portion 24 of the independent foundation 21 and the wall portion 45 of the retaining wall member 40. 【0025】 (4) In this embodiment, the wall portion 45 of the retaining wall member 40 and the foundation wall portion 24 of the independent foundation 21 are made of reinforced concrete. In this case, reinforcing bars R1 are placed in the wall portion 45 and the foundation wall portion 24, penetrating them. This makes it possible to integrally construct the foundation wall portion 24 and the wall portion 45 surrounding the seismic isolation pit EP1. 【0026】 This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically. In the above embodiment, the retaining wall member 40 is made of reinforced concrete with an L-shaped cross-section. The retaining wall member may have any shape as long as it comprises a base plate portion located outside the seismic isolation pit EP1 and a wall portion extending upward. For example, it may have a shape with an inverted T-shaped cross-section, with the wall portion at the center and the portions located on the seismic isolation pit side and the outside (soil SO1 side). 【0027】 Furthermore, as shown in Figure 6, a retaining wall member 50 may be used. This retaining wall member 50 comprises a base plate 41, a wall 45, and a mounting section 51. The mounting section 51 is made of reinforced concrete and is integrally provided with the wall 45 at the upper end of the wall 45, extending horizontally on the side opposite to the seismic isolation pit EP1. An expansion joint 60 may be provided so as to span this mounting section 51 and the floor slab 16 constructed on the upper foundation 27. This expansion joint 60 closes the area above the seismic isolation clearance S1 and functions as a blocking member that supports the load applied from above when people or vehicles pass through. 【0028】 In the above embodiment, the wall portion 45 of the retaining wall member 40 is configured to have the same width as the foundation wall portion 24 of the lower foundation 23. The wall portion 45 and the foundation wall portion 24 may have different widths, as long as they have a width that surrounds the seismic isolation pit EP1. 【0029】 In the above embodiment, a reinforcing bar R1 is provided that penetrates the wall portion 45 of the retaining wall member 40 and the foundation wall portion 24 of the lower foundation 23. The retaining wall member 40 may be constructed separately from the lower foundation 23. For example, a precast member formed in advance at a factory or a commercially available ready-made product may be used as the retaining wall member 40. In this case, the constructability can be improved by arranging the retaining wall members of the precast members. 【0030】 In the above embodiment, the retaining wall surrounding the seismic isolation pit EP1 is composed of the wall portion 45 of the retaining wall member 40 and the foundation wall portion 24 of the lower foundation 23. The retaining wall surrounding the seismic isolation pit EP1 may also be composed solely of retaining wall members. In this case, the retaining wall can be separated from the seismic isolation building erected on the independent foundation. Therefore, the retaining wall portion does not need to be included in the building permit application, making the application process simpler. 【0031】 Next, the technical concepts that can be understood from the above embodiments and alternative examples are described below. (a) A seismic isolation clearance is provided between the retaining wall and the independent foundation. The seismic isolation building according to claim 2, characterized in that the upper end of the wall portion is provided with a mounting portion for mounting a closing member that closes the area above the seismic isolation clearance and supports loads applied from above. [Explanation of Symbols] 【0032】 B1, B2... Beam, C1... Concrete, G1... Ground, R1, 23R1, 23R2, 24R1, 24R2, 45R1, 45R2, 45R3... Reinforcement, ... Reinforcement, S1... Seismic isolation clearance, EP1... Seismic isolation pit, Gi1... Ground improvement section, SO1... Soil, 10... Seismic isolation building, 11, 21... Isolated foundation, 13, 23... Lower foundation, 14, 27... Upper foundation, 16... Floor slab, 17... Covering section, 18... Wall section, 24... Foundation wall section, 25... Seismic isolation device, 29... Column, 40, 50... Retaining wall member, 41... Base plate section, 41a... Upper reinforcement, 41b... Lower reinforcement, 45... Wall section, 51... Mounting section, 60... Expansion joint as a closing member.

Claims

[Claim 1] A base-isolated building equipped with an independent foundation on which a base isolation device is installed, The aforementioned isolated foundation is located within a seismic isolation pit surrounded by a retaining wall, characterized in that it is a seismically isolated building. [Claim 2] The aforementioned independent foundation is positioned on the outer perimeter of the seismic isolation pit. It includes a retaining wall member that is positioned between the aforementioned independent foundations and forms part of the retaining wall that covers the outer perimeter of the seismic isolation pit, The seismically isolated building according to claim 1, characterized in that the retaining wall member comprises a base plate portion extending to the opposite side of the seismic isolation pit and a wall portion extending upward. [Claim 3] The aforementioned independent foundation includes the aforementioned foundation wall portion extending upward, The seismic isolation building according to claim 2, characterized in that the foundation wall portion is arranged in a manner continuous with the wall portion of the retaining wall member. [Claim 4] The aforementioned independent foundation and the aforementioned retaining wall member are made of reinforced concrete. The seismic isolation building according to claim 3, characterized in that reinforcing bars are arranged in the foundation wall and the wall, penetrating the foundation wall and the wall.

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