JPH0742167A - Foundation structure for reinforced concrete building - Google Patents

Abstract

PURPOSE:To integrally and rigidly connect a pile, a pillar, and a first floor slab in order to abolish an underground beam and a footing. CONSTITUTION:This foundation structure is constituted of a pile P constructed in the ground G, a pillar Q integrally and rigidly connected on the pile P, and a first floor slab R integrally and rigidly connected to both of them. Pillar main reinforcements 4 are gently bent outward from a pile head section 5, gradually extended obliquely downward the pile P to the positions of pile main reinforcements 1 arranged in a peripheral shape, and connected to them. The modulus of rigidity K of the pile P against the pillar Q is set to 2.5 or below. The pile main reinforcements 1 within the range of the first floor slab R are protruded from the ground surface G0 to form a rise portion 3 and connected to L-shaped reinforcing bars 10 of the floor slab R. The upper end bar 8 and lower end bar 9 of the floor slab R are extended to the space surrounded by the pillar main reinforcements 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a reinforced concrete foundation structure. More specifically, the pile, pillar and floor slab are integrally rigidly joined to each other, and the pile is reinforced by horizontal reaction force from the ground. The present invention relates to a foundation structure that is elastically supported and is particularly suitable for a reinforced concrete building.

[0002]

2. Description of the Related Art Conventionally, as a general foundation structure of reinforced concrete or steel-framed reinforced concrete, footings are provided on each foundation pile formed in the ground, and columns are formed in each footing and A structure in which footings and columns are connected to each other by underground beams (also called foundation beams) is often used. However, with the recent increase in the number of buildings, the structure of the footing foundation has become complicated, and there are many wasteful bar arrangements. The footing was abolished by directly connecting it to the lower end (see Japanese Patent Laid-Open No. 3-176508), or the footing, the underground beam, and the floor slab were integrally formed to have the same thickness as a base slab. A structure (see Japanese Patent Laid-Open No. 2-96025) has been proposed. Also, paying attention to the fact that the construction of the footing part is complicated and time-consuming, the pillars are designed so that the construction of this part can be carried out easily and quickly, and that structurally sufficient bearing capacity is exerted. Several integrated joint structures with piles have also been proposed (Japanese Patent Laid-Open No.
63-304832 and JP-A-62-284825). Each of these has a structure in which a column base is inserted into a foundation pile and integrated with concrete.

On the other hand, in a steel frame structure, Japanese Patent Laid-Open No. Hei2-164930 proposes a device for eliminating underground beams in order to simplify the foundation work. FIG.
FIG. 3 is a sectional view showing a basic structure of the steel frame building frame.
As shown in the figure, a casing 53 that serves as a discarding form is installed on the head of the cast-in-place pile 51, a plurality of anchor bolts 54 are provided in the casing 53, and the concrete in the pile head casing 53 and the floor slab 55 is installed. The anchor plate 54, which has been cast and fixed, is attached to the base plate 5 at the lower end of the steel column 52.
2a is tightly connected with a nut or the like. In the construction, the anchor bolt 54 is temporarily fixed by the fixing jig 56 using the casing 53, and a recess forming block such as polystyrene foam is formed at a portion corresponding to the column base fixing position of the anchor bolt 54. Installed and then casing 5
Concrete in 3 and floor slab 55 are simultaneously poured. After hardening the concrete, the base plate 52a of the steel column 52 is fixed to the anchor bolt 54 in the recess formed by removing the block of polystyrene foam or the like, and the grout material 60 such as high-strength non-shrink mortar is filled and surrounded. Harden. In the figure, 57 is a pile bar protruding from the head of the cast-in-place pile, 58 is a reinforcing bar for fixing the floor slab, and the pile 51, the anchor bolt 54, and the floor slab 55 on the first floor are integrated. 59 is a casing 53
Reinforcing bars placed inside.

[0004]

[Problems to be Solved by the Invention] In a reinforced concrete foundation structure, a horizontal external force is often much larger than that of a steel frame structure, and the deformation of each column base portion caused by the horizontal external force is restrained. Therefore, at least an underground beam (corresponding to this) is indispensable (for example, the above-mentioned JP-A-3-176508 or JP-A-2-176508).
(See 96025 publication). Therefore, in reinforced concrete construction, construction such as excavation and soil retention is still required to install underground beams, and it was not possible to meet the demand for shortening the construction period. Moreover, in the conventional case, since the pile does not have the technical idea of expecting elastic support from the ground (in other words, considering the rigidity of the pile including the ground), the underground beam is simply abolished. In this case, it is necessary to set the pile itself to have extremely high rigidity, which is also not practical. Further, as described in JP-A-63-304832 and JP-A-62-284825, in the structure in which the column base is inserted into the foundation pile and integrated with concrete, the column to the pile is Since the transmission of force is not direct, it is difficult to take the above technical idea.

Incidentally, the underground beam and footing are eliminated as shown in FIG.
Originally, the basic structure of No. 3 is an original structure of the steel frame structure mainly composed of the rigid connection between the steel column and the pile through the anchor bolts and the like, and naturally, it cannot be applied to the reinforced concrete structure.

Originally, in the case of a steel-framed foundation structure as shown in FIG. 13, since the bending rigidity and bending strength of the pile are much larger than those of the steel column, when a horizontal external force such as an earthquake acts on the building. , It is assumed that there is almost no lateral displacement of the pile head. In other words, since the pile is immovable and the column base is fixed to the pile head, structurally, the rigidity of the pile / the rigidity of the column (hereinafter referred to as "rigidity ratio") is 3 or more. As a result, it stands on its own without expecting elastic support from the ground.

Such a basic structure for steel frame construction is possible because it is a low-rise steel frame structure having a small number of layers, and cannot be put to practical use for the reinforced concrete structure intended by the present invention. In order to realize such a foundation structure in reinforced concrete construction, huge piles are required and it is virtually impossible.

According to the basic structure of FIG. 13, the steel columns and the piles are integrally rigidly joined, and the floor slab is rigidly joined to the piles through the anchoring reinforcing bars. Not rigidly joined. This is because the recesses around the columns are merely filled with grout material such as high-strength non-shrink mortar to solidify the periphery. Therefore, the force generated in the column base is directly transmitted to the pile, but since the floor slab and column are not rigidly connected to each other, the floor slab cannot function as an underground beam, and the column bases are disjointed from each other. May behave in

An object of the present invention is to make a pile, a pillar and a floor slab integrally rigidly connected to each other in a reinforced concrete structure, and to limit the rigidity ratio between the pile and the pillar considering the ground to a certain range. The purpose is to provide a reinforced concrete foundation structure in which the first floor is formed into a beamless structure by eliminating underground beams and footings, and a concrete foundation structure for rigidly integrating the three parties. To provide.

[0010]

To achieve the above object, the foundation structure of a reinforced concrete building according to the present invention is, in the first aspect of the invention, a pile built in the ground and a pillar erected on the pile. In a reinforced concrete structure having a floor slab laid between the pillar and the pillar, the pillar and the pile are rigidly joined, and,
First-floor slabs are rigidly joined to these piles and columns, respectively, so that the piles, columns, and first-floor slabs are integrally rigidly connected to each other, and the columns of the piles are elastically supported by the ground. It is characterized in that the rigidity ratio K (= K ₁ / K ₂ ) is set to 2.5 or less. However, K ₁ is the rigidity of the pile,
K ₂ is the rigidity of the column.

According to a second aspect of the invention, in the above-mentioned configuration, the column main reinforcement is gently bent outward from the pile head and extended to the position of the main reinforcement of the pile arranged in a substantially circular shape below the pile, The lower end portion of each of the extended column main bars is joined to the pile main bar, and in the third invention configuration, in any one of the above configurations, a part of the pile reinforcing bars arranged in a substantially circumferential shape is piled. While providing a rising portion projecting from the head, an L-shaped reinforcing bar is arranged between the upper end bar and the lower end bar of the first-floor slab, and each L-shaped bar has a fixed length at the rising part of the pile reinforcing bar. In the fourth invention configuration, the upper end bar and the lower end bar of the first floor slab are extended to a position where a fixing length can be secured in the space surrounded by the column main bar. To do.

[0012]

In the first aspect of the invention, the pillar is settled in the pile, the floor slab is set in the pile and the pillar, and the three members are rigidly integrated with each other. Therefore, the horizontal load and vertical load acting on the column are directly transmitted to the pile, and the load transmitted to the pile is gradually reduced (cancelled) by the resistance force of the ground around the pile. That is, the pile itself has a shape as if it is supported by the ground like an elastic spring. If the ground is hard, the elastic spring constant of the ground is large (the resistance from the ground is large). If the ground is soft, the elastic spring constant of the ground is small (the resistance from the ground is small). ).

In the second aspect of the invention, the column main reinforcement is inevitably joined to the pile main reinforcement with a fixed length, and a concrete rigid-contact integrated structure is realized between the two by the subsequent concrete pouring. In this case, the force from the column is directly transmitted to the pile, which results in a structurally rational structure.

In the third aspect of the invention, the first-floor slab and the piles are joined together, and a concrete rigid-joint integrated structure is realized between the two by the subsequent concrete pouring. Since the first-floor slab is supported by piles, the floor slab acts as if it were a conventional underground beam.

In the fourth aspect of the invention, the first-floor slab is joined to the pillar, and a concrete rigid-joint integrated structure is realized between the two by the subsequent concrete pouring, and in the end, the pillar, the pile, and the floor slab. Will be rigidly integrated with each other. The first-floor slab is formed as one rigid slab (structural slab), which acts like an underground beam, so that the horizontal displacement of each column base is made uniform.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. One of the features of the present invention is that the pile, the pillar, and the floor slab are rigidly integrated with each other.First, a concrete example of the rigidly integrated structure of the three is shown as a completed state of the basic structure. This will be described with reference to the cross-sectional view of FIG. 1 and the detailed views of the respective parts of FIG. The following examples are for cast-in-place piles.

The foundation structure of the present invention comprises a pile P constructed in the ground G, a pillar Q integrally rigidly connected to the pile P, and a first-floor slab R integrally rigidly connected to both of them. It is configured. The reinforcing bars of the pile P are composed of a number of longitudinally extending pile main bars 1 (Fig. 2 (a)) arranged in a circumferential shape and a number of lateral bar reinforcements 2 on the first floor. The pile main bar 1 within the slab R range protrudes from the ground surface G ₀ and rises 3
Is formed. On the other hand, the pillar main bars 4 (representing a rectangular pillar in the figure) forming the reinforcing bars of the pillar Q are arranged in a rectangular shape in a plan view. Each pillar main bar 4 is gently bent outward from the pile head 5 and is expanded downward to the position of the pile main bar 1 obliquely and gradually arranged circumferentially (Fig. 2 ( b)). The lower end of the pile is slightly bent along the main pile reinforcement 1 to form a lap joint 6 so as to be joined to the main pile reinforcement 1 (Fig. 2 (c)). At the lower end portion, the column main reinforcement 4 is bound to the main reinforcement 1 of the pile with a numbered wire or the like and joined or welded.

In this way, the column main reinforcement is gently bent from the head of the pile and extends diagonally downward so that the column main reinforcement 4 necessarily has a sufficient anchoring length. This is because, at the same time, it is possible to join the pile main bars 1 arranged in a circumferential shape, and by this, it is possible to build the column bars in advance in such a manner that they are integrally joined to the pile bars. In such a rigid structure, when a horizontal load or a vertical load is applied to the column, it is directly transmitted from the column main reinforcement to the pile main reinforcement (without the conventional footing or concrete, etc.). Durability is improved. In other words, the stress generated in the column main bar smoothly flows directly to the main bar of the pile and is transmitted. In addition, in FIG. 1, 7 shows the stirrups of a pillar.

Further, in the above structure, the rigidity ratio K between the pile and the column is set to K = K ₁ / K ₂ ≤2.5. Here, K ₁ is the rigidity of the pile and K ₂ is the rigidity of the column. The rigidity referred to here is a numerical value represented by horizontal force / horizontal displacement, and is expressed by a force for causing deformation per unit. The meaning of K ≦ 2.5 is as follows. That is, in such piles, it is planned that the column base and the pile head will be displaced, and it is expected that the pile in the ground will receive elastic spring-like support by the horizontal reaction force from the ground. Become. In other words, the rigidity (support) of the ground is ignored, and the rigidity of the pile itself does not hold, and the rigidity K ₁ of the pile is set to include the ground. As a result, the rigidity of the pile itself is the minimum necessary, and structural advantages are great (for example, the pile diameter may be small). If the ground on which the piles are built is hard, the rigidity ratio K increases, and if the ground is soft, the rigidity ratio decreases.
For example, if the ground liquefies due to an earthquake, K = 0.1 is expected. Therefore, there is no point in defining the lower limit because the variation range of the lower limit of K is wide.

Of the reinforcing bars of the floor slab R on the first floor, the lower end bar 9
Is extended into the rectangular space surrounded by the pillar main bar 4, and the upper end bar 8
Similarly, it also extends into this rectangular space, but its tip has a fixed fixing length and is bent downward in a hook shape.
An L-shaped reinforcing bar 10 is arranged in a fan-shaped (radial) shape between the upper end bar 8 and the lower end bar 9 (Fig. 2 (d)). Lap joint 1
They are joined via 1 (Fig. 2 (e)). By arranging the L-shaped reinforcing bars 10 in a fan-shaped (radial) shape, the integrity of the floor slab R and the pile P is strengthened. Thus, the floor slab R is rigidly integrated with the pillar Q and the pile P by the subsequent concrete pouring.

Next, the process of constructing the above-mentioned column, pile, and floor slab three-piece rigid joint structure will be described with time. Fig. 3 (a): Pile holes are previously dug at predetermined positions on the site to construct the desired reinforced concrete structure, the casing 12 is built at the upper end of the moat, and the stabilizing liquid is poured into it, and then the predetermined depth is reached. The pile hole 13 of is excavated. In the pile hole 13, a pile reinforcing bar 1A is constructed from the main pile reinforcing bar and the strip reinforcing bar, and a reinforcing bar cage 14 made of the column reinforcing bar 4A integrally joined to the pile reinforcing bar 1A in advance is built by a crane. FIG. 3 (b): Next, the tremie pipe 15 is set in the rebar cage 14 and concrete is poured from below the pile hole 13.

FIG. 4 (a): Concrete C is poured and filled upward while successively pulling up the tremie pipe 15. After placing concrete C to a predetermined height, discard formwork 1
6 is partially projected from the ground surface G ₀ and attached to the inner circumference of the casing 12, and concrete C is further placed. Fig. 4 (b): When it is driven to a position slightly below the ground surface G _{0, a} so-called slime treatment is performed to suck up defective concrete on the upper part of the pile with a vacuum hose H. Then, only the casing 12 is pulled out and the concrete pouring is completed.

FIG. 5 (a) is a cross-sectional view of the upper part of the pile in the state where the concrete has been poured, and the discarding form 16, the pillar main bar 4 and the rising part 3 of the pile main bar 1 project from the concrete pouring surface. There is. 5 (b) to (d): Inking is performed, and the part on the floor slab on the planned laying side is left, and part of the formwork 16 is cut off to prepare for backfilling (Fig. (C)). . Then, the backfill soil 17 is laid at a predetermined height at the site where the floor slab is to be formed (Fig. (D)).

6 (a) and 6 (b): As shown in the enlarged view of FIG. 6 (b), gravel laying and waste concrete 18 are placed on the backfill soil 17 to the height position of the waste form 16. . The rising portion 3 of the pile main bar 1 projects slightly above the discard form 16.

7 (a)-(c): Columns and first floor slabs are reinforced. 8 to 10 are a perspective view and a plan view showing the details. First, as shown in Fig. 8 (a), the reinforcement of columns (arrangement of the stirrups 7)
I do. Next, as shown in FIG. 7 (a) to FIG. 8 (b), the wall rising bar arrangement 19 and the floor slab lower end bar 9 are arranged. As shown in FIG. 8 (c), the lower end streak 9 is arranged vertically and horizontally so as to sew the rising part 3 of the pile main bar, and secures a sufficient fixing length up to the rectangular space 4A surrounded by the column main bar 4. Has been extended. Then, as shown in FIGS. 7 (b) and 9 (a) (b), L
The type reinforcing bars 10 are arranged in the fan-shaped (radial) shape above the lower end bars 9 of the floor slab in a plan view by the number corresponding to the rising portions 3 of the pile main bars in plan view. That is, as shown in FIG. 2 (e), one side of the L-shaped reinforcing bar 10 is overlapped downward along the rising part 3 of the main reinforcement of the pile, and the overlapped parts of the both are joined by welding, number wire, or the like. . With this configuration, the rigid slab reinforcement of the floor slab reinforcement and the pile reinforcement is realized by the subsequent concrete pouring. Then Fig. 7 (c) and Fig. 10
As shown in (a) and (b), the upper end bar 8 of the floor slab is arranged above the lower end bar 9 in the same manner as the lower end bar 9 described above. However, although the lower end streak 9 extends straight to the main post bar 4, the tip of the upper end streak 8 has a downwardly hooked portion 8a in the space 4A of the post bar (FIGS. 1 to 7 (c)). . By arranging the upper end bar 8 and the lower end bar 9 even in the space 4A of the column main bar 4, the column and the floor slab are rigidly integrated by subsequent concrete placing. After the reinforcement of the first-floor slab is completed, after the stop formwork 20 such as columns is installed as shown in Fig. 11 (a), the columns and floor slab concrete are placed as shown in Fig. 11 (b). Fill and finally form a three-piece rigid joint structure of piles, columns and floor slabs.

The operation of the above configuration will be described with reference to FIG. Since the pile P, the pillar Q, and the first-floor slab R are rigidly integrated, the load 21 from above transmitted via the pillar Q is directly applied to the pile P without an intermediate medium. It will be transmitted. On the other hand, the horizontal load 22 transmitted via the pillar Q is also transmitted directly to the pile P. The horizontal load 22 transmitted to the pile P gradually decreases due to the horizontal resistance forces 23a to 23c from the ground G around the pile. The pile body and the soil around the pile are integrated to resist a horizontal load. That is, the pile P is supported by the ground G around the pile as if it were supported by an elastic spring. That is, the ground G
The force for resisting in the horizontal direction is considered to be replaced by the elastic springs 23A to 23C ...
The horizontal loads 22a to 22c on the piles are canceled by ...
It becomes smaller gradually. In this regard, the structural idea that was conventionally considered by separating the building into the upper part up to the footing and the pile, and thinking that the connection between the footing and the pile is an intermediate (semi-fixed) intermediate between pin connection and rigid connection Totally different. In other words, the conventional reinforced concrete structure structurally supports the load (vertical and horizontal directions) transmitted from the upper part of the column as a reaction force under the footing, and the reaction force is conversely regarded as an action force and applied to the pile. In addition, the bending moment generated in the pile head was partly applied to the underground beam to resist the horizontal load in the form of pile, underground beam and column. It is different from the inventive idea.

[0027]

In the structure of the present invention, the pile, the pillar, and the first floor slab are integrally rigidly joined, and the resistance of the ground is also taken into consideration.
Since it comes to resist external force and the load from the upper part is directly transmitted to the pile, the yield strength of the foundation structure is greatly exerted and a highly reliable foundation structure can be obtained. Further, various forces generated in the column base due to horizontal external force such as during an earthquake are directly transmitted to the pile and the floor slab, so that the bending rigidity of the pile and the floor slab can be effectively used. With the floor slab provided integrally with the piles and columns, each column base does not behave in a disjointed manner, and because the floor slab resists with the piles and columns, stable yield strength can be exhibited together. . Based on the above, foundation beams,
Footing is not required, basic construction is simplified, construction period is shortened, and cost can be reduced. Furthermore, since the amount of underground excavation is reduced, the amount of waste soil disposal can be reduced, which can contribute to environmental measures.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure in which a pillar, a pile, and a floor slab are rigidly joined together according to an embodiment of the present invention.

2 (a) to (e) are cross-sectional views taken along line AA, BB, cross-section C, enlarged line DD, cross-section DD, cross-section DD, rising part of pile reinforcement and L-shaped reinforcement of floor slab in FIG. 1, respectively. 3 is a detailed view of the joint of FIG.

3 (a) and (b) are a sectional view showing a state in which a reinforced cage in which a pile and a column are integrated is built in a pile hole, and a tremie pipe set in the pile hole.

4 (a) and 4 (b) are a diagram showing a state in which concrete is placed in a pile hole from below and a cross-sectional view showing a state in which the upper portion of the pile hole is slime-treated.

[Fig. 5] Fig. 5 (a) is a cross-sectional view of the state in which the concrete has been poured into the pile holes, (b) is a perspective view when marking out, and (c) is a part of the discard formwork for backfill preparation. Perspective view when scraped off,
(d) is a cross-sectional view when backfilled soil is put in.

FIG. 6 (a) is a cross-sectional view of a state in which gravel floor and waste concrete are cast, and FIG. 6 (b) is an enlarged view thereof.

FIG. 7 (a) is a bar arrangement diagram of the lower end bar of the first floor floor slab, (b) is a bar arrangement diagram of the L-shaped reinforcing bar, and (c) is a bar arrangement diagram of the upper end bar of the floor slab.

FIG. 8 (a) is a perspective view of the reinforcement of the stirrup of the column, (b) is a perspective view showing the rise of the wall and the reinforcement of the lower end reinforcement of the first floor slab,
(c) is a plan view thereof.

FIG. 9 (a) is a perspective view of an L-shaped reinforcing bar, and FIG. 9 (b) is a plan view thereof.

10 (a) is a perspective view of the floor slab with the upper end streaks arranged, and FIG. 10 (b) is a plan view thereof.

FIG. 11 (a) is a cross-sectional view when a stationary form such as a pillar is installed, and FIG. 11 (b) is a cross-sectional view of a state in which concrete is placed on the pillar and the floor slab.

12 (a) and 12 (b) are explanatory views of the operation of the present invention.

FIG. 13 is a basic structural diagram for a conventional steel frame structure.

[Explanation of symbols]

 P ... Pile Q ... Pillar R ... (1st floor) Floor slab 1 ... Pile main bar 3 ... Rising part 4 ... Pillar main bar 5 ... Pile head 8 ... Upper end bar 9 ... Lower end bar 10 ... L-shaped rebar

Claims (4)

[Claims] 1. In a reinforced concrete structure having a pile built in the ground, a pillar standing on the pile, and a floor slab laid between the pillars, the pillar and the pile are rigidly joined, and Rigidly join the first floor slab to the pile and the pillar,
The pile, the pillar, and the first-floor slab are integrally rigidly connected to each other, and the rigidity ratio K (= K ₁ / K ₂ ) of the pile to the pillar is 2.5 or less in order to elastically support the pile by the ground. The basic structure of the reinforced concrete building characterized by the setting. However, K ₁ is the rigidity of the pile and K ₂ is the rigidity of the column. 2. The column main bars are gently bent outward from the pile head and extend to the position of the pile main bars arranged in a substantially circular shape below the pile, and the lower end portion of each of the extended column main bars. The foundation structure of the reinforced concrete structure according to claim 1, wherein the main reinforcement is connected to the pile. 3. A part of the pile reinforcing bars arranged in a substantially circular shape is projected from the pile head to provide a rising portion, while an L-shaped reinforcing bar is arranged between the upper end bar and the lower end bar of the first floor slab. 3. The foundation structure of a reinforced concrete building according to claim 1 or 2, wherein each L-shaped reinforcing bar is joined to a rising portion of the pile reinforcing bar with a fixed length. 4. The first floor slab has an upper end bar and a lower bar which are extended to a position where a fixed length can be secured in a space surrounded by a column main bar. The basic structure of a reinforced concrete building according to item 1.