JPH09310368A - Foundation in base isolation structure for building, and its construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make construction of foundation simple and to reduce term of works therefor by a method wherein a continuous footing of a building is divided into upper and lower parts and formed in a slidable surface contact structure, and the upper continuous footing is slid when an earthquake occurs against the lower continuous footing that is wider in width. SOLUTION: A continuous footing is divided into two parts of upper and lower continuous footings, and the lower continuous footing 2 is made up of a foundation concrete layer 6 formed on the ground 5 and the surface of its upper side is made flat and smooth. The lower continuous footing 2 may be joined with chains 7 to the upper continuous footing 3 provided thereupon. The upper continuous footing 3 is formed of a metal support body 10 such as I-steel, and the lower end face 10a thereof comes into surface contact with the upper face 6a of the lower continuous footing 2 while the upper end face 10b thereof supports a groundsill 9 of a building. The lower continuous footing 2 and the upper continuous footing 3 are in a slidable contact each other. Thereby, acceleration inputted to the upper continuous footing is small even though vibration frequency and acceleration on an earthquake vary, and a force bigger than a product of total weight of the building and a coefficient of friction between the upper and the lower continuous footings is not applied to the building.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base isolation structure for a building (including various buildings and structures in this specification) and a construction method therefor, and more specifically, to a fabric foundation of a building. The present invention relates to a seismic isolation basic structure of a building and a construction method thereof, which can shorten a construction period and can be a seismic isolated building by simple construction.

[0002]

[Prior Art] As a basic structure of a building,
There are cloth foundations, independent foundations, solid foundations, etc. In recent years, cloth foundations are mainly used for small-scale structures such as houses. Then, as shown in FIGS. 7 and 8, the cloth foundation 40 is dug down to a site having soil resistance of the ground 47, and after the split stone layer 41 and the discarded concrete layer 42 are constructed, on the discarded concrete layer 42. In addition, the cloth foundation widened portion 43 and the cloth foundation rising portion 44 are formed by reinforced concrete construction (or non-reinforced concrete construction). Then, the cloth foundation rising portion 44 of the cloth foundation 40
The anchor bolt 45 is inserted into the hole formed in the base 46 of the building, and the base is fixed to the cloth foundation 40 to construct the building.

By the way, in recent years, in order to impart seismic resistance to a building, a bearing and an elastic body (spring or oil damper) are interposed between a cloth foundation and a base, and the bearing and the elastic body make different directions. It has been proposed to absorb the displacement from the building to reduce the shaking of the building (for example, see Japanese Utility Model Laid-Open No. 62-173464). In the case of such a seismic isolation device, displacements from multiple directions can be absorbed at the same time, so that it is possible to deal with complex earthquakes and vibrations.

[0004]

However, the above-mentioned seismic isolation foundation structure for buildings is not suitable for construction of cloth foundations. In particular, when it is necessary to make a reinforced concrete structure with a cloth foundation, in addition to embedding anchor bolts for fixing the foundation of the building, reinforcement work is required, so reinforcement, anchor bolt placement, concrete placement , Curing and construction period of several days are required. Since the bearing is a structure that bears the weight of the building, the structure of the bearing unit becomes complicated, and the horizontal displacement is applied to the bearing, which reduces the durability of the bearing. It's easy to do. Further, since all the vibrations from the concrete foundation are directly transmitted to the bearings and the elastic body, some of the vibrations are absorbed by the bearings and the elastic body, but cannot be sufficiently absorbed. And other issues.

The present invention has been made in response to the above problems, and its purpose is to make it possible to shorten the construction period of the cloth foundation of a building and to carry out a simple construction. The purpose of the present invention is to provide a seismic isolation basic structure of a building that can be a seismic isolated building and its construction method.

[0006]

A seismic isolation base structure for a building according to claim 1 as means for solving the above-mentioned problems, wherein the building base is an upper cloth foundation and a lower cloth foundation. And a structure in which the upper surface of the lower cloth base and the lower surface of the upper cloth base are slidable, and the upper surface of the lower cloth base is wider than the lower surface of the upper cloth base.
When an earthquake occurs, the upper cloth foundation is slid with respect to the lower cloth foundation.

According to a second aspect of the present invention, in the structure of the first aspect of the present invention, in the structure of the first aspect, the upper cloth foundation portion is made of metal such as I-type steel, inverted H-type steel, or inverted T-type steel. Characterize. The base isolation structure for a building according to claim 3 is the structure according to claim 1 or 2, wherein the upper cloth foundation portion and the lower cloth foundation portion are connected by a connecting tool such as a chain. It is characterized in that the sliding range of the upper cloth foundation part with respect to is restricted. Claim 4
In the structure according to any one of claims 1 to 3, the base isolation structure for a building is characterized in that the lower cloth foundation portion is a solid concrete foundation.

The construction method of the seismic isolation base structure for a building according to claim 5 of the present invention is the construction method for the seismic isolation base structure for a building according to any one of claims 1 to 4. And a step of constructing the lower cloth foundation portion on the ground, and a step of standing an upper cloth foundation portion on the upper surface of the lower cloth foundation portion so as to be slidable with respect to the lower cloth foundation portion. To do.

Here, the cloth foundation (also called continuous foundation)
Includes waist-high cloth foundations, cloth foundations combined with earthen concrete floor slabs, or foundations connecting the cloth foundations with large beams or small beams. The lower cloth foundation portion, the upper surface of which is exposed on the ground, or on the ground, or by slightly digging up the ground, after forming a predetermined reinforcement, it is formed by placing concrete, the concrete thickness, The thickness of the concrete is wide enough to allow it to withstand the load of the building, and the concrete width is wider than the allowable sliding range of the upper cloth foundation. Further, the upper surface of the lower cloth foundation portion makes surface contact with the lower surface of the upper cloth foundation portion, and forms a surface that slides the upper cloth foundation portion with respect to the lower cloth foundation portion when an earthquake occurs. Therefore, it is preferable to form a certain degree of surface smoothness, and the friction coefficient between the two is preferably equal to or less than the designed horizontal proof stress. The upper fabric foundation is usually I-shaped steel, H-shaped steel or inverted T
Although it is formed of a metal such as a shaped steel, it can be formed of, for example, an FRP, a reinforced concrete holding body, or the like having strength equivalent to this, and the base of the building is fixed or fixed on the upper part of the upper cloth foundation part. A base fixing / holding means for holding is formed, and this base fixing / holding means is formed by a concave groove or a bolt hole.

A chain, a wire, or the like is used as a connecting structure between the upper cloth foundation portion and the lower cloth foundation portion, which corresponds to the wind pressure applied to the building on the upper cloth foundation portion. The lower part of the cloth and the lower cloth foundation part may be connected to each other. In this case, it is preferable that the length of the chain can be adjusted.

Further, in the seismic isolation base structure of the building of the present invention, the lower cloth foundation portion whose surface is exposed on the ground and the upper cloth foundation portion which holds the foundation of the building are in surface contact, and the upper portion Since the cloth foundation is slidable with respect to the lower cloth foundation,
When an earthquake occurs, the upper cloth foundation slides against the lower cloth foundation, so even if the frequency and acceleration of the earthquake change, the input acceleration to the upper cloth foundation that holds the building Low, the building is not subjected to more than the product of the total weight of the building and the coefficient of friction between the upper and lower foundations. Therefore,
Seismic resistance against earthquakes can be added.

[0012]

As is apparent from the above description, according to the base isolation structure for a building of claim 1 of the present invention, unlike the conventional cloth foundation of the building, the cloth foundation is used as the upper cloth foundation portion. And the lower cloth foundation portion are divided into two parts, the construction can be easily performed, the upper cloth foundation portion and the lower cloth foundation portion are in surface contact with each other, and the upper cloth foundation portion is attached to the lower cloth foundation portion. Since it is slidable, the sliding absorbs energy due to vibration during an earthquake, so that there is an effect that a base-isolated building can be obtained with a simple structure.

According to the seismic isolation base structure for a building of claim 2, since the upper cloth foundation portion is made of metal such as H-section steel or inverted T-section steel, its workability can be improved.
In addition, it has an effect that the upper building can be stably held. According to the seismic isolation basic structure for a building of claim 3, the upper cloth foundation portion and the lower cloth foundation portion are made of a chain or the like corresponding to the lifting force of wind pressure applied to the building on the upper cloth foundation portion. Since the connector has a structure for restricting the allowable sliding range, it is possible to avoid a problem such as floating of a building due to the wind pressure. Further, according to the seismic isolation foundation structure for a building of claim 4, since the lower cloth foundation portion is a solid foundation, there is an effect that the construction can be performed more easily.

According to the method for constructing a seismic isolated foundation structure for a building according to claim 5, after the lower cloth foundation portion is constructed on the ground, the upper surface of the lower cloth foundation portion is attached to the upper surface of the lower cloth foundation portion. On the other hand, since the upper cloth foundation portion is erected so as to be slidable, there is an effect that the construction period can be shortened.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. Here, FIG.
4 shows one embodiment of the present invention, and FIG.
(B) is a schematic vertical sectional view of a building with a base-isolated base structure,
2 (a), (b) and (c) are enlarged cross-sectional views for explaining the base isolation base structure, FIG. 3 is a plan view of the base isolation base part, and FIG. 4 (a)
FIG. 3B is a perspective view of portions A and B of FIG.

The seismic isolation base structure of the building of the present embodiment is a cloth base structure having a base structure capable of preventing or reducing vibration energy due to an earthquake from being applied to the building,
In summary, as shown in FIGS. 1 to 4, a cloth foundation (continuous foundation) 1 is divided into a lower cloth foundation portion 2 and an upper cloth foundation portion 3, and the upper cloth foundation portion 3 is used for building 4 construction. It is configured to hold.

As shown in FIG. 2 (a), the lower cloth foundation portion 2 is composed of a foundation concrete layer 6 made of reinforced concrete on the ground 5, and an upper surface 6a thereof is horizontal, flat, and smooth. have. Further, the concrete layer 6 is formed to have strength capable of holding the weight of the building 4 and having resistance to soil, and its size is larger than the bottom surface of the building 4. An upper cloth foundation portion 3 is provided on the upper surface of the lower cloth foundation portion 2. The upper surface of the foundation concrete layer 6 may be formed into a concave surface 13 as shown in FIG. In the case of this configuration, it is possible to prevent the upper cloth base portion 3 from sliding and moving more than necessary. The lower cloth foundation portion 2 and the upper cloth foundation portion 3 are connected by a chain 7. The length of the chain 7 is such that the upper cloth base portion 3 is allowed to slide with respect to the lower cloth base portion 2, and the chain 7 can be detachable as required.

The upper cloth foundation portion 3 is a foundation portion for holding the base 9 of the building 4 with respect to the lower cloth foundation portion 2,
It is formed of a metal support 10 such as an I-shaped steel, an inverted T-shaped steel, and an H-shaped steel which is laid down. The lower end surface 10a of the metal support 10 is in surface contact with the upper surface 6a of the lower cloth foundation portion 2, and the upper end surface 10b is capable of holding the base 9 of the building 4. FIG. 2C shows a case where the upper cloth base portion 3 is formed of I-shaped steel, and the upper cloth base portion 3 and the base 9 made of this I-shaped steel are connected and fixed by the anchor bolts 15. Further, the upper cloth foundation portion 3 is formed by connecting a plurality of metal supporting bodies 10 as shown in FIG. That is, the end portions of the adjacent metal supports 10 are bolted or welded to each other to form a continuous upper base, and the metal support 10 is similarly formed of a metal support, if necessary. They are connected by a large beam 11 and a small beam 12 that are formed. Here, the metal support 10 ensures the strength capable of holding the building 4 constructed thereon,
A plate having a thickness of about 6 mm to 9 mm is used. As a matter of course, it is possible to select and use a preferable one depending on the building.

The lower cloth foundation portion 2 and the upper cloth foundation portion 3 are in contact with each other such that the upper cloth foundation portion 3 slidably contacts the lower cloth foundation portion 2, and the building 4 is exposed to a wind pressure higher than a predetermined level due to a typhoon or the like. In such a case, a means for holding both the foundation parts 2 and 3 in a fixed state is provided, and this fixing means is formed by the chain 7 as described above.

Next, a method of constructing the seismic isolation base structure for a building of this embodiment will be described. First, based on a design document, a predetermined portion of the ground 5 is dug up to a predetermined depth at a portion where the building 4 is to be constructed and constructed, and if necessary, a split stone is inserted to form a split stone layer, and then the split stone layer is formed. The reinforcement 14 and the anchor 14 for attaching the chain 7 are arranged on the cobblestone layer, and concrete is poured and cured to obtain the foundation cloth foundation portion 2 including the foundation concrete layer 6. The upper surface 6a of the base cloth base portion 2 is formed so as to be exposed to the ground 5, and has a dense structure so that the surface has smoothness. Subsequently, the upper cloth foundation portion 3 is installed at a predetermined position on the upper surface 6a of the base cloth foundation portion 2. The upper cloth base portion 3 is formed by bolting or welding and connecting a plurality of metal support bodies 10 made of I-shaped steel or the like on the basis of the design document. Then, the upper end 1 of this metal support 10
The base 9 constituting the building 4 is fixed to 0b, and the building is constructed by a normal construction method (conventional construction method, 2 × 4 construction method, ALC construction method, or panel construction method).

Therefore, according to the construction method of this embodiment,
The cloth foundation part 1 is divided into a lower cloth foundation part 2 and an upper cloth foundation part 3, and the lower cloth foundation part 2 can be simply formed by a concrete layer, that is, can be formed as a solid foundation, and this lower cloth foundation part can also be formed. Since the metal supports 10 are arranged side by side on the part 2 based on the design document, and the adjacent metal supports 10 are simply connected to each other by means such as bolting, production in the factory, Since the processing ratio can be increased and the site work ratio can be reduced, the work of the cloth foundation can be shortened and the workability thereof can be improved. Further, since the upper cloth foundation portion 3 is configured to be slidable with respect to the lower cloth foundation portion 2, the vibration-isolated foundation structure can be easily obtained.

[0022]

[Embodiment] Next, in order to confirm the operation and effect of the base isolation structure for a building according to the present embodiment, a vibration applying plate for earthquake test is arranged on the floor of the room, and concrete is placed on this. Then
Formed a lower cloth foundation consisting of a solid concrete layer of length: 2 m × width: 3 m, and laid horizontally on top of it (thickness: 6
mm, upper and lower plate width: 150 mm, height: 300 mm) are connected and connected in a frame shape, and a frame-shaped upper cloth foundation portion having a length of 1.8 m and a width of 2.7 m is erected, and the upper cloth foundation portion is A wooden building by the panel construction method on the above, vibrates the vibration test plate for earthquake test at a frequency of 1 Hz to 20 Hz, transfers vibration energy to the lower cloth foundation, and the building at each frequency The acceleration response of was measured. At the same time, for comparison, the lower cloth foundation and the upper cloth foundation were fixed and the acceleration response was measured in the same manner. The result is as shown in FIG.

As shown in FIG. 5, in both the present embodiment and the conventional example, a peak was observed in the response acceleration when the frequency was 8 Hz, but in the case of the present embodiment, the peak value is 200.
In contrast with the conventional example, 800
It was gal. From this, in the present embodiment, there is a sliding state between the lower cloth foundation portion and the upper cloth foundation portion, and the vibration energy of the lower cloth foundation portion is absorbed between the both foundation portions. It can be confirmed that the seismic isolation effect is obtained.

By the way, the present invention is not limited to the above-mentioned embodiments, and it is needless to say that the present invention can be modified and implemented within a range not departing from the gist of the present invention. Incidentally, in the above-described embodiment, the metal support forming the upper cloth foundation is described as a form in which the vertical surface thereof is a plate-shaped body such as I-type steel, but the vertical surface is for ventilation and the like. A structure with holes or openings may be used, or a structure in combination with an independent foundation (in this case, the lower independent foundation part and the upper independent foundation part having a divided basic structure are also used) May be Moreover, in the said embodiment, although it demonstrated by the structure formed with the foundation concrete layer which consists of a concrete solid foundation as a lower cloth foundation part, as shown in FIG. The connection may be performed by the chain 13 and the anchor 14. Further, the lower cloth foundation is not limited to the solid foundation, and is formed of a concrete layer wider than the lower surface of the upper cloth foundation, and the upper surface of the concrete layer may be a form in which the upper cloth foundation slides. The good thing is right.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a building having a base isolation structure according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view for explaining a base isolation structure.

FIG. 3 is a plan view of a base isolation base.

4A and 4B are perspective views of portions A and B in FIG.

FIG. 5 is a graph showing the relationship between vibration frequency and response acceleration in an implementation test.

FIG. 6 is an enlarged cross-sectional view of another embodiment.

FIG. 7 is a cross-sectional view of a conventional cloth foundation structure.

FIG. 8 is a schematic vertical sectional view of a building constructed on a conventional cloth foundation structure.

[Explanation of symbols]

1 ... Fabric foundation (continuous foundation), 2 ... Lower fabric foundation,
3 ... upper cloth foundation part, 4 ... building, 5 ... ground, 6 ... foundation concrete layer, 6a ... upper surface,
7 ... Chain, 9 ... Building base, 10 ...
Metal support 10a ... Lower end surface, 10b ... Upper end surface, 11 ... Large beam, 12 ... Small beam, 13 ...
Concave, 14 ... Anchor, 15 ... Anchor bolt

Claims (5)

[Claims] 1. A structure in which a cloth foundation of a building is divided into an upper cloth foundation portion and a lower cloth foundation portion, and an upper surface of the lower cloth foundation portion and a lower surface of the upper cloth foundation portion are slidable surface contact structures. In addition, the upper surface of the lower cloth foundation is made wider than the lower surface of the upper cloth foundation, and the upper cloth foundation is slid relative to the lower cloth foundation when an earthquake occurs. Earthquake foundation structure. 2. The seismic isolation base structure for a building according to claim 1, wherein the upper cloth foundation portion is made of a metal such as an I-section steel, an inverted H-section steel, or an inverted T-section steel. 3. The upper cloth foundation and the lower cloth foundation are connected by a connecting tool such as a chain, and the sliding range of the upper cloth foundation with respect to the lower cloth foundation is restricted. Seismic isolation base structure for the listed building. 4. The base isolation structure for a building according to claim 1, wherein the lower cloth foundation portion is a solid foundation. 5. A method for constructing a seismic isolation foundation structure for a building according to claim 1, comprising the step of constructing the lower cloth foundation portion on the ground, and the lower cloth foundation structure. A method for constructing a seismic isolation foundation structure for a building, comprising the step of vertically arranging an upper cloth foundation portion on the upper surface of the portion so as to be slidable with respect to the lower cloth foundation portion.