JP3887248B2 - Support structure for concrete foundation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a support structure for a concrete foundation using piles.
[0002]
[Prior art]
Conventionally, for example, a support structure for supporting a footing foundation 20 '(concrete foundation) by a steel pipe hollow pile 10' has been generally performed by rigidly joining the two as follows.
[0003]
That is, as shown in FIG. 3 (a), the first joining structure 50 penetrates the upper end portion of the steel pipe hollow pile 10 ′ into the footing foundation 20 ′, and the predetermined structure in the hollow portion of the steel pipe hollow pile 10 ′. A bottom plate 13 ′ is provided at a position, and the embedded concrete 14 ′ is filled in the hollow portion at the top of the bottom plate 13 ′, and is rigidly joined integrally with the footing foundation 20 ′. Then, in order to resist bending stress and shearing stress (hereinafter sometimes referred to as “bending stress etc.”) generated in the joint, a pile protruded from the filling portion of the embedded concrete 14 ′ into the footing foundation 20 ′. By arranging a plurality of axial reinforcing bars 35 ′ in the axial direction and reinforcing band bars 36 ′ (hereinafter sometimes referred to as “reinforcing reinforcing bars”) surrounding the axial reinforcing bars 35 ′, a joint portion is formed. The structure is configured.
[0004]
Moreover, as shown in FIG.3 (b), the 2nd joining structure 60 penetrates the length beyond the diameter of the pile from the upper end part of steel pipe hollow pile 10 'into the inside of footing foundation 20', and the said steel pipe By providing a bottom plate 13 'at a predetermined position in the hollow portion of the hollow pile 10', filling the embedded concrete 14 'in the hollow portion at the top of the bottom plate 13' and integrating it with the footing foundation 20 ', a steel pipe hollow pile The structure resists bending stress and the like generated in the joint portion due to the penetration of 10 '.
[0005]
[Problems to be solved by the invention]
However, when the first joint structure 50 is adopted, the bending stress generated by rigidly joining the footing foundation 20 ′ and the steel pipe hollow pile 10 ′ becomes excessive, so a large amount of reinforcing bars are arranged. It was necessary to make a footing foundation 20 'having an excessive cross section. In addition, the reinforcing reinforcing bars interfere with the reinforcing bars (not shown) of the footing foundation 20 ', which has hindered the bar arrangement work.
Further, when the second joining structure 60 is adopted, the penetration portion of the steel pipe hollow pile 10 'interferes with the reinforcing bar of the footing foundation 20', similarly to the case where the first joining structure 50 is adopted. The problem had occurred.
[0006]
Furthermore, analysis of the relationship between the load acting on the joint between the footing foundation 20 ′ and the steel pipe hollow pile 10 ′ and the state of stress has progressed in recent years, and ground conditions, load conditions or construction methods have been developed. As a result of this, the places where the joints do not necessarily have to be rigidly joined are often revealed at the design stage. However, even in such a case, since a method for substituting the support structure has not been developed, the support structure must be adopted uniformly. As it becomes complicated and overdesigned, the work efficiency when placing the footing foundation 20 'is lowered and the construction cost is increased. .
[0007]
The present invention has been made to solve the above-mentioned problems, and even when a concrete foundation or pile is subjected to a large horizontal force, excessive cross-sectional force does not occur, design rationality and construction. It aims at providing the support structure of the concrete foundation which can guarantee the easiness of.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a concrete foundation support structure (hereinafter referred to as “support structure”) according to the present invention is a steel pipe hollow pile having a concrete foundation and a pile head portion in which concrete is filled at the tip. It is a support structure of a concrete foundation that is supported by being placed on a concrete structure, and is characterized in that a concrete design standard strength of the steel pipe hollow pile is larger than a concrete design standard strength of the concrete foundation. .
[0009]
The support structure of the present invention is a support structure for a concrete foundation that supports the concrete foundation in a state of being placed on the cast-in-place concrete pile, and is a design standard for concrete at the pile head of the cast-in-place concrete pile. The strength is characterized by being larger than the concrete design standard strength of the concrete foundation.
[0010]
Here, placing means that the concrete foundation is only placed on the pile head in supporting the concrete foundation, and the edges of both are cut off. . In addition, a concave portion is formed in the concrete foundation, and the concrete structure is inserted in the concave portion with a pile head of a steel pipe hollow pile and cast-in-place concrete pile (hereinafter sometimes abbreviated as “steel pipe hollow pile”). Supporting the foundation and providing an uneven portion for transmitting a horizontal force between the concrete foundation and the steel pipe hollow pile do not disturb the support form of placement.
[0011]
In addition, concrete is a material that hardens and becomes integrated in the pile head of a steel pipe hollow pile or the like, and any material can be used as long as it has such properties, but it expands when a steel pipe hollow pile is used. With the use of expansive concrete, the expansion concrete and the outer shell steel pipe forming the steel pipe hollow pile are firmly integrated with the expansion force when cured, and stress transmission can be reliably performed. Is preferred.
[0012]
According to the present invention, by supporting the concrete foundation in a state where it is placed on a steel pipe hollow pile or the like, even if a horizontal force acts on the concrete foundation or the like, both of them move vertically with respect to each other. Since movement and rotation are not constrained, it is possible to prevent excessive cross-sectional force from being generated in the concrete foundation and steel pipe hollow pile, etc., and rationality of design and ease of construction are ensured. It will be.
In addition, since the concrete design standard strength of the pile head is greater than the concrete design standard strength of the concrete foundation, the pile head may be damaged even if excessive support pressure is applied to the pile head. Can be prevented.
[0013]
Further, in the support structure for the concrete foundation, if the core steel material is arranged between the concrete foundation and the pile head, the pulling force generated between the concrete foundation and the pile head is reduced. It can resist effectively.
[0014]
Moreover, in the support structure of the concrete foundation, if the inner wall surface of the pile head of the steel pipe hollow pile is provided with a groove-like, protruding uneven portion or protruding steel material, concrete and Adhesion with the steel pipe hollow pile can be improved, and stress transmission from the concrete foundation to the steel pipe hollow pile can be effectively performed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described in detail with reference to the drawings.
In the description of each embodiment, the same constituent elements are denoted by the same reference numerals, and redundant descriptions are omitted.
[0016]
[First Embodiment]
The first embodiment of the support structure S of the present invention is a structure in which the footing foundation 20 is supported by the steel pipe hollow pile 10.
As shown in FIG. 1, the steel pipe hollow pile 10 uses a shell steel pipe 11 having a circular cross section as a main body part, and a lower end part reaches a support layer (not shown) of the ground G. A bottom plate 13 is provided at a predetermined position in the hollow portion of the upper end portion (tip portion) of the outer shell steel pipe 11, and concrete 14 described later is filled in the hollow portion in the upper portion of the bottom plate 13. Thus, a pile head 12 is formed, and the outer shell steel pipe 11 and the concrete 14 are integrated in the pile head 12.
The footing foundation 20 is supported in a state of being placed on the steel pipe hollow pile 10.
[0017]
Furthermore, as one of the features of the support structure S of the present invention, concretes having different design standard strengths are divided into concrete 21 in the footing foundation 20 and concrete 14 filled in the pile head 12 of the hollow steel pipe pile 10. Has been used.
[0018]
That is, the concrete having the design standard strength larger than the concrete 21 of the footing foundation 20 is used for the concrete 14 of the pile head 12 (in the above example, the design standard strength of each concrete is 60 N / mm ² and 36 N). / Mm ² ). As described above, the reason why the concretes having different design standard strengths are divided is that the reinforcement is made against the bearing stress acting on the bottom portion of the footing foundation 20 and the pile head portion 12, and in particular, The pile head 12 having a small cross-sectional area is made of concrete having a particularly high design standard strength to enhance the proof stress.
[0019]
In addition, a core rebar may be arranged between the footing foundation 20 and the pile head 12 in the support structure S.
Moreover, in the inner wall surface of the outer shell steel pipe 11 of the pile head part 12, you may provide a horizontal rib member, such as a groove shape which consists of steel materials in the circumferential direction, or a vertical rib member in the pile axial direction. It is more preferable that a through hole is formed in the vertical rib member in order to ensure the integrity with the concrete.
[0020]
Then, the effect of the said support structure S is demonstrated.
When an earthquake occurs, the steel pipe hollow pile 10 integrated with the ground G vibrates in response to the vibration of the ground G, and the footing foundation 20 also vibrates through the steel pipe hollow pile 10.
[0021]
At this time, since the footing foundation 20 and the steel pipe hollow pile 10 have different natural vibration periods, they try to vibrate independently. Then, since a frictional force is generated between the footing foundation 20 and the pile head 12, both receive a horizontal force.
[0022]
However, the support structure S of the present invention is not a structure in which the footing foundation and the hollow steel pipe pile restrain vertical movement, horizontal movement and rotation with each other as in the conventional support structure, but the footing foundation 20 is placed on the steel pipe hollow pile 10. Since it is the structure which has mounted and received the load, it can prevent that the cross-sectional force generate | occur | produces in the said footing foundation 20 and the steel pipe hollow pile 10 generate | occur | produces. Accordingly, since it is not necessary to arrange a large number of reinforcing bars at the joint between the footing foundation 20 and the steel pipe hollow pile 10, the footing foundation 20 does not have an excessive cross-sectional structure. Reinforcing bars that are arranged in the part do not interfere with the reinforcing bars of the footing foundation, so the structure is simple, labor saving work can be achieved, and construction costs can be reduced. .
[0023]
Further, since the design standard strength of the concrete 14 in the pile head 12 is set to be larger than the design standard strength of the concrete 21 in the footing foundation 20, an excessive support pressure is applied to the pile head 12. Even in the case, the pile head 12 can be prevented from being damaged.
[0024]
[Second Embodiment]
Unlike the support structure S of 1st Embodiment, 2nd Embodiment of support structure S 'of this invention uses the cast-in-place concrete pile 10' instead of the hollow steel pipe pile 10 (refer FIG. 2).
[0025]
In the support structure S ′ of the present embodiment, concrete having a design standard strength higher than that of the concrete 21 in the region of the footing foundation 20 is used for the concrete 14 of the cast-in-place concrete pile 10 ′.
[0026]
Furthermore, between the footing foundation 20 and the pile head 12 'of the cast-in-place concrete 10', there are a plurality of core rebars 30 (core steel materials) fixed in the vicinity of the cross-sectional center of the pile head 12 '. The bar is arranged. The core rebar 30 is provided between the concrete 21 of the footing foundation 20 and the pile head 12 '.
[0027]
Therefore, according to the support structure S ′ of the present embodiment, the types of piles are different, but the same effect as the support structure S of the first embodiment is achieved, and between the footing foundation 20 and the pile head 12 ′. Since the core reinforcing bars 30 are arranged, the pulling force generated between the footing foundation 20 and the pile head 12 'can be effectively resisted. Further, since the core rebar 30 is fixed in the vicinity of the cross-sectional center of the pile head portion 12 ′, the transmission of the bending moment by the core rebar 30 can be reduced.
[0028]
Heretofore, an example of a preferred embodiment has been described for the present invention. However, the present invention is not limited to the above-described embodiment, and the design of each of the above-described components can be appropriately changed without departing from the spirit of the present invention. In particular, it goes without saying that the dimensions, material, arrangement, etc. of each element are appropriately determined according to the construction object.
[0029]
【The invention's effect】
According to the support structure of the present invention, even when a concrete foundation or pile receives a large horizontal force, an excessive cross-sectional force does not occur, and it is possible to ensure rational design and ease of construction. Become.
[Brief description of the drawings]
1A and 1B are diagrams showing a concrete structure supporting structure (first embodiment) according to the present invention, in which FIG. 1A is a side sectional view, and FIG. 1B is a sectional view taken along line XX in FIG.
2A and 2B are diagrams showing a concrete structure supporting structure (second embodiment) according to the present invention, in which FIG. 2A is a side sectional view and FIG. 2B is a YY sectional view of FIG. .
FIGS. 3A and 3B are side sectional views showing a conventional support structure for a concrete foundation. FIGS.
[Explanation of symbols]
S, S 'support structure (support structure of concrete foundation)
DESCRIPTION OF SYMBOLS 10 Steel pipe hollow pile 10 'Cast-in-place concrete pile 11 Outer shell steel pipe 11a Hollow part 12, 12' Pile heads 14, 14 ', 21 Concrete 15 Horizontal rib member 20 Footing foundation 30 Core rebar (core steel material)

Claims (4)

A concrete foundation support structure for supporting a concrete foundation in a state where the concrete foundation is placed on a steel pipe hollow pile having a pile head filled with concrete at the tip,
A concrete foundation support structure, wherein a concrete design standard strength of the steel pipe hollow pile is larger than a concrete design standard strength of the concrete foundation. A concrete foundation support structure for supporting a concrete foundation in a state of being placed on a cast-in-place concrete pile,
A concrete foundation support structure, wherein a concrete design standard strength of a pile head of the cast-in-place concrete pile is larger than a concrete design standard strength of the concrete foundation. The support structure for a concrete foundation according to claim 1 or 2, wherein a core steel material is arranged between the concrete foundation and the pile head. The support structure for a concrete foundation according to claim 1, wherein a groove-like, protruding uneven portion or protruding steel material is provided on an inner wall surface of the steel pipe hollow pile at the pile head.

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