JP2603427B2 - Foundation structure of reinforced concrete building - Google Patents

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, and more particularly, to a pile, a column and a floor slab, which are integrally rigidly connected to each other, and the pile is formed by a horizontal reaction force from the ground. The present invention relates to a foundation structure adapted to be supported by an elastic spring and 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, a footing is provided on each foundation pile formed in the ground, and a column is formed in each footing. A structure in which a footing and a column are connected to each other by an underground beam (also referred to as a foundation beam) is often used. However, due to the recent rise in height of buildings, the structure of the footing foundation has become complicated, and there are many wasteful reinforcements. To solve this problem, the upper ends of the pile reinforcements and the column reinforcements with the underground beams left unsolved. The footing is abolished by directly connecting to the lower end of the floor (see Japanese Patent Application Laid-Open No. 3-176508), or the footing, the underground beam and the floor slab are integrally formed to the same thickness as the base slab. A configuration (refer to Japanese Patent Application Laid-Open No. 2-96025) has been proposed. Also, paying attention to the complicated and time-consuming construction of the footing part, a pillar that can easily and quickly construct this part and has sufficient structural bearing capacity Several integral joint structures with piles have also been proposed.
See JP-A-63-304832 and JP-A-62-284825). Each of them 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 structure, a device for eliminating the underground beam has been proposed in Japanese Patent Application Laid-Open No. 2-149930 to simplify the foundation work and the like. FIG.
FIG. 2 is a sectional view showing a basic structure of the steel frame.
As shown in the figure, a casing 53 serving as a disposal form is installed at the head of the cast-in-place pile 51, a plurality of anchor bolts 54 are provided in the casing 53, and concrete in the pile head casing 53 and the floor slab 55 is removed. The base plate 5 at the lower end of the steel column 52 is attached to the anchor bolt 54 which is cast and fixed.
2a is tied with a nut or the like. In the construction, the anchor bolt 54 is temporarily fixed using a casing 53 by a fixing jig 56, and a concave forming block such as a polystyrene foam is provided in a portion corresponding to the column base fixing position of the anchor bolt 54. Install the casing 5
3 and the concrete of the floor slab 55 are simultaneously poured. After the concrete is hardened, the base plate 52a of the steel column 52 is fixed to the anchor bolts 54 in the recess formed by removing the block of the polystyrene foam or the like, and the grout material 60 such as a high-strength non-shrink mortar is filled to surround the recess. Solidify. In the figure, reference numeral 57 denotes a pile bar protruding from the head of the cast-in-place pile, 58 denotes 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 arranged inside.

[0004]

In a reinforced concrete foundation structure, a horizontal external force is often much larger than that of a steel frame structure. In order to restrain deformation of each column base caused by the horizontal external force, a conventional structure is used. Therefore, at least an underground beam (equivalent to this) is indispensable (see JP-A-3-176508 and JP-A-2-176508 described above).
96025). Therefore, in the case of reinforced concrete structures, construction work such as excavation and earth retaining is still required to install underground beams, and this has not met the demand for shortening the construction period. In addition, in the conventional case, the underground beam was simply abolished because the pile did not take the technical idea of expecting elastic support from the ground (in other words, considering the rigidity of the pile including the ground). In this case, it is necessary to set the pile itself to a very rigid one, which is not practical. In addition, as described in JP-A-63-304832 and JP-A-62-284825, in a structure in which a column pedestal is inserted into a foundation pile and integrated with concrete, the structure from the column to the pile is Since the transmission of force is not direct, the above technical idea is difficult to take.

[0005] In addition, the underground beams and footing have been abolished.
Originally, the foundation structure of No. 3 is an original structure of a steel frame mainly composed of a rigid connection between a steel column and a pile via an anchor bolt or the like, and cannot be naturally applied to a reinforced concrete structure.

Originally, in the case of a steel frame foundation structure as shown in FIG. 13, since the bending rigidity and the bending strength of the pile are much larger than those of the steel column, when a horizontal external force acts on the building at the time of an earthquake or the like. It is assumed that there is almost no lateral displacement of the pile head. That is, 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 is independent without expecting elastic support from the ground.

[0007] Such a steel structure foundation structure is a possible structure because it is a low-rise steel structure with a small number of layers, and cannot be put to practical use in the reinforced concrete structure aimed at by the present invention. In order to realize such a foundation structure in reinforced concrete, a huge pile is required, which is practically impossible.

According to the basic structure shown in FIG. 13, the steel column and the pile are rigidly connected integrally, and the floor slab is rigidly connected to the pile via the anchoring rebar. Not rigidly connected. This is because the recess around the column is merely filled with a grout material such as high-strength non-shrink mortar to solidify the periphery. Therefore, the force generated at the column base is transmitted directly to the pile, but the floor slab and the column are not integrally rigidly connected, so the floor slab cannot serve as an underground beam, and the column pedestals are disjointed from each other. May behave.

An object of the present invention is to provide a reinforced concrete structure in which a pile, a column and a floor slab are integrally rigidly connected to each other to limit the rigidity ratio between the pile and the column in consideration of the ground to a certain range. Abolished underground beams and footings to provide a reinforced concrete foundation structure in which the first floor is formed as a beamless slab, and a concrete foundation structure for rigidly integrating the three members Is to provide.

[0010]

In order to achieve the above objects, the basic structure of a reinforced concrete building according to the present invention comprises, in the first invention configuration, a pile built in the ground and a pillar erected on the pile. And in a reinforced concrete structure having a floor slab laid between the columns, rigidly connecting the columns and the piles, and
The first floor slab is rigidly connected to each of the piles and columns, so that the pile, the columns and the first floor slab are integrally rigidly connected to each other, and the pile columns are elastically supported by the ground. The rigidity ratio K (= K ₁ / K ₂ ) is set to 2.5 or less. However, K ₁ is the pile of rigidity,
K ₂ is the stiffness of the pillar.

According to a second aspect of the present invention, in the above configuration, the column main reinforcement is gently bent outward from the pile head and extended to the pile main reinforcement positioned substantially circumferentially below the pile. The lower end portion of each of the extended column main reinforcements is joined to the pile main reinforcement, and in the third invention configuration, in any of the above configurations, a part of the pile reinforcement arranged in a substantially circumferential shape is piled. While providing a rising portion protruding from the head, an L-shaped reinforcing bar is arranged between an upper end bar and a lower end bar of the first floor slab, and each L-shaped reinforcing bar is fixed to a rising portion of the pile reinforcing bar. According to a fourth aspect of the present invention, the upper and lower muscles of the first floor slab are extended to a position where the anchoring length can be secured in a space surrounded by the main pillars. I do.

[0012]

In the first aspect of the present invention, the pillar is fixed in the pile, the floor slab is fixed in the pile and the pillar, and the three members are rigidly integrated with each other. Therefore, the horizontal load, the vertical load, and the like acting on the column are directly transmitted to the pile, and the load transmitted to the pile gradually decreases (cancels) due to the resistance of the ground around the pile. That is, the pile itself has a shape as if it was supported by the ground in an elastic spring manner. If the ground is hard, the elastic spring constant of the ground increases (the resistance from the ground increases). If the ground is soft, the elastic spring constant of the ground decreases (the resistance from the ground decreases) ).

In the second invention, the column main reinforcement is inevitably joined to the pile main reinforcement with a fixed length, and a concrete rigid integrated structure between the two is realized by the subsequent concrete casting. In this case, since the force from the column is directly transmitted to the pile, a structurally rational configuration is obtained.

In the third aspect of the invention, the first floor slab and the pile are joined, and a concrete and rigid integrated structure between them is realized by concrete casting thereafter. Because the first floor slab is supported by piles, the floor slab acts as if it were a conventional underground beam.

In the fourth invention, the first-floor floor slab is joined to the column, and a concrete concrete integrated structure between the two is realized by the subsequent casting of concrete. Are rigidly integrated with each other. The first-floor slab is formed as one rigid slab (structural slab), which works in the same way as 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 feature of the present invention resides in that the three members of the pile, the column and the floor slab are rigidly integrated with each other. First, a concrete example of the rigidly integrated structure of the three members is used to describe the completed state of the basic structure. This will be described with reference to the cross-sectional view of FIG. The following embodiment is for a cast-in-place pile.

The foundation structure of the present invention comprises a pile P constructed in the ground G, a column Q rigidly connected to the pile P, and a first-floor slab R integrally rigidly connected to the both. It is configured. The reinforcing bar of the pile P is composed of a number of longitudinally extending pile reinforcing bars 1 (FIG. 2 (a)) and a number of lateral reinforcing bars 2 arranged on the first floor. The main pile 1 in the range of the slab R protrudes from the ground surface G ₀ and rises 3
Is formed. On the other hand, the column main reinforcement 4 constituting the reinforcing bar of the column Q (the figure illustrates a rectangular column) is arranged in a rectangular shape in plan view. Each pillar main reinforcement 4 is gently bent outward from the pile head 5 and gradually expands diagonally downwardly below the pile P to the position of the circumferentially arranged pile reinforcement 1 (FIG. 2 ( b)) is extended. The lower end portion is slightly bent along the main pile bar 1 to form a lap joint 6 to be joined to the main pile bar 1 (FIG. 2 (c)). At this lower end, the column main reinforcement 4 is bound to the pile main reinforcement 1 by a wire or the like and joined or welded.

The reason that the column main reinforcement is gently bent from the pile head and extends obliquely downward is that this configuration inevitably allows the column main reinforcement 4 to have a sufficient anchoring length. This is because, at the same time as possible, it is possible to join with the pile main reinforcement 1 that is arranged circumferentially, so that the column reinforcement can be preliminarily joined and integrated with the pile reinforcement. In such a rigid connection structure, when a horizontal load or a vertical load acts on a column, it is transmitted directly from the column main reinforcement to the pile main reinforcement (without the intervention of footing or concrete as in the past), Proof stress is increased. In other words, the stress generated in the column main bar smoothly flows and is directly transmitted to the pile main bar. In addition, in FIG. 1, 7 shows the stirrup 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 here is a numerical value expressed 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. In other words, in such a pile, the column base and the pile head are expected to be displaced, and it is expected that the pile in the ground will be elastically supported by the horizontal reaction force from the ground. Become. Conversely, ignores the soil rigidity (supporting) Yes configured not hold true only rigid pile itself, the stiffness K ₁ of the pile is set to one, including ground. Accordingly, the rigidity of the pile itself can be minimized, so that the structural advantage is large (for example, the pile diameter can be small). If the ground on which the pile is built is hard, the rigidity ratio K increases, and if the ground becomes soft, the rigidity ratio decreases.
For example, if the ground liquefies due to an earthquake, it is expected that K = 0.1. Therefore, there is no point in defining the lower limit because the range of variation of the lower limit of K is wide.

Among the reinforcing bars of the floor slab R on the first floor, the lower reinforcing bars 9
Extends into the rectangular space surrounded by the column main reinforcement 4,
Is also extended to the inside of this rectangular space, but its tip has a fixed fixing length and is bent downward like a hook.
An L-shaped reinforcing bar 10 is arranged between the upper and lower bars 8 and 9 in a fan-shaped (radial) shape (FIG. 2 (d)). Lap joint 1
1 (FIG. 2 (e)). By arranging the L-shaped reinforcing bars 10 in a fan (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 column Q and the pile P by the subsequent concrete casting.

Next, a process of constructing the above-mentioned three-piece rigid connection structure of the column, the pile, and the floor slab will be described with time. Fig. 3 (a): A pile hole is preliminarily dug at a predetermined position of the site to construct a desired reinforced concrete building, a casing 12 is built at the upper end of the moat, and a predetermined liquid is injected at a predetermined depth. Is excavated. A pile reinforcing bar 1A is built into the pile hole 13 from the pile main bar and the band reinforcing bar, and a reinforcing bar cage 14 composed of the column reinforcing bar 4A integrally joined to the pile reinforcing bar 1A in advance as described above. FIG. 3 (b): Next, the tremy tube 15 is set in the reinforcing steel basket 14 and concrete is poured from below the pile hole 13.

FIG. 4 (a): Concrete C is poured and filled upward while sequentially pulling up the tremy tube 15. After concrete C is cast to a predetermined height,
6 was partly protruded from the ground surface G ₀ attached to the inner periphery of the casing 12, it will further Da設concrete C. FIG 4 (b): when pouring slightly to a position below the ground surface G _0, to the so-called slime processing blotting defective concrete pile top with vacuum hose H. Thereafter, only the casing 12 is pulled out to complete the concrete placement.

FIG. 5 (a) is a cross-sectional view of the upper part of the pile in a state in which the concrete has been cast, in which the dumping formwork 16, the column main reinforcement 4, and the rising part 3 of the pile main reinforcement 1 project from the surface of the concrete. I have. 5 (b) to 5 (d): Ink marking is performed, and the part on the side where the floor slab is to be laid is left, and the partly discarded formwork 16 is cut and removed to prepare for backfilling (FIG. . 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), a gravel bed and concrete 18 are cast on the backfill soil 17 up to the level of the form 16 for disposal. . The rising portion 3 of the main pile 1 protrudes slightly above the disposal form 16.

FIGS. 7 (a) to 7 (c): Reinforcing columns and first floor slabs. 8 to 10 are a perspective view and a plan view showing the details. First, as shown in Fig. 8 (a), the reinforcing bars of the columns (the bars 7 are arranged)
I do. Next, as shown in FIGS. 7 (a) and 8 (b), the reinforcement of the wall rising reinforcement 19 and the lower reinforcement 9 of the floor slab are performed. As shown in FIG. 8 (c), the lower end bars 9 are arranged vertically and horizontally so as to sew the rising portions 3 of the main bars of the pile, and secure a sufficient anchoring length to the inside of the rectangular space 4A surrounded by the main bars 4 of the pillars. Has been extended. Next, as shown in FIGS. 7 (b) and 9 (a) (b), L
The reinforcing bars 10 are arranged in a fan-shaped (radial) shape in plan view above the lower end bar 9 of the floor slab in a number corresponding to the rising portion 3 of the pile main reinforcing bar. That is, as shown in FIG. 2 (e), one side of the L-shaped reinforcing bar 10 is superimposed downward along the rising portion 3 of the pile main bar, and these superposed portions are joined by welding, a number line, or the like. . With this configuration, rigid integration of the floor slab reinforcement and the pile reinforcement is realized by the subsequent concrete casting. Then Figure 7 (c) and Figure 10
As shown in (a) and (b), the upper end muscle 8 of the floor slab is arranged above the lower end muscle 9 in the same manner as the above-described lower end muscle 9. However, the lower end muscle 9 extends straight up to the column main muscle 4, but the tip of the upper end muscle 8 has a portion 8a bent downward in a hook shape in the space 4A of the column muscle (FIGS. 1 to 7 (c)). . By arranging the upper end reinforcement 8 and the lower end reinforcement 9 in the space 4A of the column main reinforcement 4, the column and the floor slab are rigidly integrated by the subsequent concrete casting. After the reinforcement of the first-floor floor slab is completed, after installing the stop formwork 20 such as a pillar as shown in FIG. 11 (a), the pillar and floor slab concrete are poured as shown in FIG. 11 (b). Filling and finally forming a three-piece rigid joint structure of pile, column and floor slab.

Here, the operation of the above configuration will be described with reference to FIG. Since the pile P, the column Q and the first floor slab R are rigidly integrated, the load 21 transmitted from above transmitted through the column Q is directly applied to the pile P without passing through an intermediate medium. Be transmitted. On the other hand, the horizontal load 22 transmitted via the column Q is also transmitted directly to the pile P. The horizontal load 22 transmitted to the pile P gradually decreases due to horizontal resistances 23a to 23c from the ground G around the pile. The pile body and the ground around the pile are integrated to resist horizontal load. In other words, the pile P is supported as if it were an elastic spring from the ground G around the pile. That is, the ground G
Are replaced by the elastic springs 23A to 23C, and the horizontal resistances 23a to 23c are considered.
The horizontal loads 22a to 22c generated on the pile due to ... are offset,
It becomes smaller gradually. In this regard, what is the structural philosophy that previously considered the building to be separated into the upper part up to the footing and the pile, and considered the connection between the footing and the pile as an intermediate (semi-fixed) between pin connection and rigid connection Completely different. In other words, conventional reinforced concrete structures structurally support the load (vertical and horizontal directions) transmitted from the top of the column as a reaction force under footing, and capture the reaction force as an acting force to act on the pile. In this method, some bending moments generated at the pile head were borne by the underground beams, and the piles, underground beams, and columns resisted horizontal loads. This is different from the inventive idea.

[0027]

According to the structure of the present invention, the pile, the column, and the first floor slab are integrally rigidly connected, taking into account the resistance of the ground,
Since it comes to resist external force and the load from the upper part is directly transmitted to the pile, the strength of the foundation structure is exerted greatly, and a highly reliable foundation structure can be obtained. In addition, various forces generated on the column pedestal due to a horizontal external force during an earthquake or the like 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. By the floor slab integrally provided with the pile and the column, each column-base does not behave in a disjointed manner, and the floor slab together with the pile and the column can exhibit a stable strength together. . From the above, foundation beams,
Footing is not required, foundation work is simplified, construction period is shortened, and costs can be reduced. Furthermore, by reducing underground excavation, the amount of residual soil disposal can be reduced, which can contribute to environmental measures.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an integral rigid contact structure of a pillar, a pile, and a floor slab according to one embodiment of the present invention.

2 (a) to 2 (e) are cross-sectional views taken along lines AA, BB, C, and DD in FIG. 1, respectively. FIG. 3 is a detailed view of the joint of FIG.

FIGS. 3 (a) and 3 (b) are a diagram showing a state in which a reinforced car in which a pile and a column are integrated is built in a pile hole, and a sectional view showing a state in which a tremy tube is set in the pile hole.

FIGS. 4 (a) and 4 (b) are a view showing a state in which concrete is poured into a pile hole from below, and a cross-sectional view in a state where slime treatment is performed on an upper portion of the pile hole.

Fig. 5 (a) is a cross-sectional view of a state in which concrete has been poured into a pile hole, (b) is a perspective view when inking is performed, and (c) is a part of a discarded formwork in preparation for backfilling. Perspective view when shaved off,
(d) is a cross-sectional view when backfill soil is inserted.

FIG. 6 (a) is a cross-sectional view of a state in which a gravel pavement and abandoned concrete are cast, and FIG.

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

FIG. 8 (a) is a perspective view of a reinforcing bar of a stirrup of a column, FIG. 8 (b) is a perspective view of a rising of a wall and a reinforcing bar of a lower end of a first floor slab,
(c) is a plan view thereof.

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

FIG. 10 (a) is a perspective view of a floor slab when upper end bars are arranged, and FIG. 10 (b) is a plan view thereof.

11 (a) is a cross-sectional view when a stop form such as a pillar is installed, and FIG. 11 (b) is a cross-sectional view in a state where concrete is poured into a column and a floor slab.

FIGS. 12 (a) and 12 (b) are diagrams for explaining the operation of the present invention.

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

[Explanation of symbols]

 P… Pile Q… Column R… (1st floor) Floor slab 1… Pile main bar 3… Rising part 4… Column main bar 5… Pile head 8… Top bar 9… Bottom bar 10… L-shaped bar

Claims (4)

(57) [Claims] 1. A reinforced concrete structure having a pile built in the ground, a pillar erected on the pile, and a floor slab laid between the pillars, wherein the pillar and the pile are rigidly joined, and Rigidly connecting the first floor slabs to the piles and columns,
The three members of the pile, the column and the first floor slab are integrally rigidly connected to each other, and the rigidity ratio K (= K ₁ / K ₂ ) to the column of the pile is set to 2.5 or less so that the pile is elastically supported by the ground. The basic structure of a reinforced concrete building characterized by the setting. However, K ₁ is the stiffness of the pile, K ₂ is the stiffness of the pillar. 2. The pillar main reinforcement is gently bent outward from the pile head and extended to the position of the pile main reinforcement arranged substantially circumferentially below the pile, and a lower end portion of each of the extended column main reinforcements. 2. The foundation structure of a reinforced concrete building according to claim 1, wherein the main structure is joined to the main bar of the pile. 3. A part of a substantially circumferentially arranged pile reinforcing bar protrudes from a pile head to provide a rising portion, while an L-shaped reinforcing bar is arranged between an upper end bar and a lower end bar of the first floor slab. 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 floor slab according to claim 1, wherein the upper and lower struts of the first floor slab are extended to a position where the anchoring length can be secured in a space surrounded by the main pillars. 2. The foundation structure of the reinforced concrete building according to item 1.