JP2006138095A - Cast-in-place steel pipe reinforced concrete pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cast-in-place steel pipe reinforced concrete pile which can ensure stress transfer between a steel pipe and reinforced concrete by preventing slip between the steel pipe and the concrete, which can be manufactured by virtue of a high degree of design freedom, which does not deteriorate the infilling of the concrete in the placing of the concrete, and which can restrain hole wall slurry from affecting a force of adhesion between the concrete and the steel pipe. <P>SOLUTION: An upper section 10 of the pile comprises: the vertically elongated steel pipe 11 with a smooth inner surface; a plurality of anchor bars 12 which are fixed to the upper outer peripheral surface or inner peripheral surface of the steel pipe by welding or a bolt etc. and elongated into a footing 1 of reinforced concrete construction; a plurality of first annular ribs 13 with a chevron-shaped cross section, which are formed on the inner surface of the lower end of the steel pipe at axial intervals; a plurality of first pile main reinforcements 14 which are provided inside the first annular ribs in such a manner as to be elongated to the lower end of the steel pile from a lower section of the pipe; a plurality of first hoop reinforcements 15 which enclose the first pile main reinforcements in such a manner as to be orthogonal to the first pile main reinforcements; and the concrete 16 which is continuously infilled into the steel pipe from an upper end to a lower end. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a foundation pile that supports a building on a hard ground in a deep underground, and more particularly, to a spot cast steel pipe concrete pile.

  FIG. 9 is a diagram showing an example of a conventional on-site steel pipe concrete pile. In this figure, the lower part 53 is made of reinforced concrete, and the upper part of the pile 52 is made of steel pipe concrete. Is done.

In normal times, the vertical load corresponding to the weight of the building is transmitted as an axial force from the pillar or foundation beam of the building to the footing 51, and through the concrete in the steel pipe of the pile upper part 52 and the pile 54. It is transmitted and supported to the hard ground in the deep underground through the reinforced concrete of the lower part 53.
Further, when the building shakes in the horizontal direction during an earthquake, a horizontal force acts on the upper portion of the footing 51, and a bending moment, an axial force, and a shear force act on the pile body. Therefore, it is necessary for the joint part 54 of the cast-in-place steel pipe concrete pile to be able to reliably transmit this bending moment, axial force and shearing force acting on the pile upper part to the pile lower part, and various configurations have been proposed (for example, And Patent Documents 1 to 3).

  As shown in FIG. 10, the “pile head coupling method using a cage bar” disclosed in Patent Document 1 has a cage so that a deformed reinforcing bar 61 as a main bar of a stake bar for a pile head is in contact with an inner surface of a steel pipe 62 of a steel pipe concrete pile. A bar is manufactured, and the deformed bar 61 is inserted into the steel pipe to a predetermined depth while being in contact with the inner surface of the steel pipe 62, and then the concrete 64 is driven into the steel pipe 62 to fix the cage bar and the steel pipe concrete pile. Is. Moreover, if the steel pipe with the rib 63 attached to the inner surface is used as the steel pipe 62, the adhesion between the cage bar and the steel pipe concrete pile can be further strengthened.

  As shown in FIG. 11, “Pile head structure of cast-in-place steel pipe concrete pile” in Patent Document 2 is formed from a high-strength reinforcing bar on the inner peripheral surface of the steel pipe 71 constituting the cast-in-place steel pipe concrete pile at substantially equal intervals. The lower end portion of the fixing muscle 72 is disposed with the distance between the fixing muscle 72 and the steel pipe 71 set to be 1.5 times the diameter D of the fixing muscle 72, and at least one end portion of the fixing muscle 72 is fixed to the fixing member 73 and 74 are arranged, and the upper end of the fixing muscle 72 is extended to the footing construction position.

  As shown in FIG. 12, the “place-cast steel pipe concrete pile” of Patent Document 3 has steel pipes 81 constituting the steel pipe concrete portion 80 installed at three locations, a steel pipe main body 82, upper and lower end portions thereof, and a central portion. A configuration including a diaphragm 84 is provided.

Japanese Patent Laid-Open No. 5-230841, “Pile Head Coupling Method Using Basket Muscle” JP 2000-355940 A, “Pile head structure of cast-in-place steel pile concrete pile” Japanese Patent Application Laid-Open No. 2004-250984, “Placed Steel Pipe Concrete Pile”

  As described above, the joint portion of the on-site steel pipe concrete pile needs to be able to reliably transmit the bending moment, the axial force and the shearing force acting on the pile upper part to the pile lower part during an earthquake.

  As in Patent Documents 1 and 2, when a deformed reinforcing bar or fixing bar serving as a main reinforcing bar is welded to the inner surface of a steel pipe, stress transmission from the main reinforcing bar to the steel pipe can be performed smoothly. However, if the inner surface of the steel pipe is smooth between the steel pipe and the concrete inside, a slip occurs between the steel pipe and the concrete, so that the stress transmission from the steel pipe to the reinforced concrete and the stress transmission from the reinforced concrete to the steel pipe are ensured. There is a problem that will not go.

Therefore, so-called “ribbed steel pipe” having ribs on the inner surface of the steel pipe is conventionally used as a steel pipe for piles (see, for example, Patent Document 1). The ribbed steel pipe is a spiral steel pipe in which a ribbed steel plate formed with ribs during rolling with a roll is spirally wound and joined.
Since the ribbed steel pipe has ribs formed on the inner surface of the steel pipe, the steel pipe and the concrete have high adhesion, and the stress transmission from the steel pipe to the concrete or from the concrete to the steel pipe is reliably performed.
However, the steel pipe with ribs has a problem in that the shape, dimensions, and interval of the protrusions and the range for attaching the protrusions cannot be freely changed due to the manufacturing method, that is, the economical design cannot be performed.

In Patent Document 3, as an improvement plan, diaphragms are provided at a plurality of locations in the vertical direction of the steel pipe. However, regarding the diaphragms concerned, there are the following concerns as a steel pile concrete pile.
In-situ steel pipe concrete piles form a pile hole in the ground, insert a reinforcing bar rod (cylindrical rebar network composed of reinforcing bars called main reinforcement and ribs) and a steel pipe, from the bottom of the pile hole It is constructed by placing concrete toward the top.
The pile hole is filled with a hole wall stabilizing liquid such as bentonite in order to prevent the pile hole wall from collapsing, and concrete is placed while pushing up these holes.
Therefore, when diaphragms are provided at a plurality of locations in the vertical direction of the steel pipe, there is a concern that the concrete is not completely filled into the steel pipe and the corners of the diaphragm when the exit width of the diaphragm is large. If the concrete is not completely filled, the strength of the steel pipe concrete will be reduced. Therefore, a means for appropriately processing is required, which requires a lot of work.

  On the other hand, conventional cast-in-place steel pipe concrete piles using steel pipes with ribs cannot increase the height of protrusions because the protrusions are formed by rolling, and a mixture of concrete and hole wall stabilizing liquid is retained during concrete placement. The influence of the corners of the grooves between the protrusions, which are easy to deform, was large, and it was easily affected by the adhesion between concrete and steel pipe.

  The present invention has been developed to solve these problems. That is, the object of the present invention is to (1) prevent slippage between a steel pipe and concrete, ensure stress transmission between the steel pipe and reinforced concrete, and (2) have a high degree of design freedom and can be made inexpensive ( 3) It is to provide a cast-in-place steel pipe concrete pile that can suppress the underfilling of concrete and the residual of the mixture of the concrete and the hole wall stabilizing liquid, leading to the deterioration of the quality of the steel pipe concrete.

According to the present invention, a steel-pipe concrete pile upper part and a reinforced concrete pile lower part are in-situ steel pipe concrete piles,
The upper part of the pile is a steel pipe that extends vertically and has a smooth inner surface, a plurality of fixing bars that are fixed to the upper outer peripheral surface or inner peripheral surface of the steel pipe by welding or bolts and extend into a reinforced concrete footing, and the inner surface of the lower end of the steel pipe A plurality of first annular ribs having a mountain-shaped cross section formed at intervals in the axial direction, and a plurality of first pile main bars extending from the bottom of the pile to the inside of the lower end of the steel pipe inside the first annular rib; There is provided a spot cast steel pipe concrete pile characterized by comprising a plurality of hoop bars orthogonal to and surrounding the first pile main bar and concrete continuously filled from the upper end to the lower end in the steel pipe. .

  According to a preferred embodiment of the present invention, it further includes a plurality of second pile main bars having lower ends fixed to a part or all of the plurality of first pile main bars and extending to the footing.

  According to another preferred embodiment of the present invention, a plurality of second annular ribs having a mountain-shaped cross section formed on the inner surface of the upper end portion of the steel pipe at an interval in the axial direction, and the inner side of the second annular rib A plurality of third pile main bars extending from the footing to the upper end of the steel pipe.

  According to another preferred embodiment of the present invention, a lower end is fixed to some or all of the plurality of first pile main bars, and an upper end is fixed to some or all of the plurality of third pile main bars, A plurality of fourth pile main bars extending in the horizontal direction.

  The first annular rib and / or the second annular rib have a shape and a number of strips (the number of windings when the rib is spiral) so as to correspond to the proof stress necessary for the joint portion.

  The first annular rib and / or the second annular rib are arranged such that a pair of contact plates are arranged at an interval on the inner surface or outer surface of the steel pipe, and the pair of contact plates are moved relative to the inner surface or outer surface of the steel pipe. It is preferable that the welded rib is formed by overlay welding between the contact plates.

  In addition, the first annular rib and / or the second annular rib has a height of 6 mm or more, a width of 5 mm or more, and an angle formed between the side portion and the inner surface or the outer surface of the steel pipe is 60 ° to 90 °. It is preferable to have a curved protrusion having a straight portion and a curved upper portion.

According to the configuration of the present invention described above, a plurality of first annular ribs having a mountain-shaped cross-section are formed on the inner surface of the lower end portion of the steel pipe, and the concrete located inside thereof has a structure in the lower end portion of the steel pipe from the lower part of the pile. Since so-called reinforcing bar rods are made up of a plurality of first pile main bars and a plurality of hoop bars, the first annular rib is made to correspond to the required strength at the joint between the pile upper part and the pile lower part. By setting the shape and the number of strips (when the rib is spiral, the number of turns), slippage between the steel pipe and concrete can be prevented, and stress transmission between the steel pipe and reinforced concrete can be ensured.
In addition, since the first annular rib can be freely set in shape and number of strips (ie, the number of windings when the rib is spiral) by overlay welding or other means, the degree of freedom in design is high and the cost can be reduced.
Further, the first annular rib has a height of 6 mm or more, a width of 5 mm or more, an angle formed between the side portion and the inner surface or the outer surface of the steel pipe is 60 ° to 90 °, has a linear portion on the side portion, and has an upper portion. Because it has curved projections that become curved, there is no influence of the corners of the grooves between the projections when placing concrete, without impairing the filling of the concrete and where the mixture of concrete and pore wall stabilizing liquid tends to stay. The effect on the adhesion between the concrete and the steel pipe can be suppressed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 (A) is a diagram showing a first embodiment of a spot cast steel pipe concrete pile according to the present invention. As shown in this figure, the in-situ steel pipe concrete pile of the present invention is composed of a steel pipe concrete pile upper part 10 and a reinforced concrete pile lower part 3. Hereinafter, the part joined to the pile lower part 3 in the pile upper part 10, that is, the lower end part is referred to as a “joint part”.

The pile upper portion 10 includes a steel pipe 11, a plurality of fixing bars 12, a plurality of first annular ribs 13, a plurality of first pile main bars 14, a plurality of hoop bars 15, and concrete 16.
The steel pipe 11 is a steel pipe that extends vertically in use and has a smooth inner surface, such as a straight seam steel pipe.

The plurality of fixing bars 12 are fixed to the upper outer peripheral surface or inner peripheral surface of the steel pipe 11 with welding or bolts and extend into the reinforced concrete footing 1.
In FIG. 1A, the footing 1 is reinforced concrete, but the illustration of the reinforcing bars is omitted. Further, a plurality of fixing bars 12 are fixed along the outer periphery or inner periphery of the steel pipe 11, but only two on the side surface are shown.

  The first annular rib 13 has a mountain shape in cross section, and is formed on the inner surface of the lower end portion (that is, the joint portion 18) of the steel pipe 11 with an interval in the axial direction.

The first pile main reinforcement 14 extends from the pile lower portion 3 to the inside of the lower end portion of the steel pipe 11 inside the first annular rib 13. The hoop bar 15 is orthogonal to and surrounds the first pile main bar 14.
In the joint part 18 and the pile lower part 3, a plurality of first pile main bars 14 are arranged in a cylindrical shape in the vertical direction, and there is a circular hoop bar 15 in a direction orthogonal to the first pile main bars 14, FIG. As shown, a so-called reinforcing bar is formed. In FIG. 1A, only four of the first pile main bars are shown.

  The concrete 16 is continuously filled in the steel pipe 11 from the upper end to the lower end.

The first annular rib 13 is formed only in a portion corresponding to the joint portion 18 between the pile upper portion 10 and the pile lower portion 3.
It is preferable that the first annular rib 13 (and a second annular rib to be described later) form a build-up weld projection having an angled cross section on the inner periphery of the steel pipe by carbon dioxide shield welding, MIG welding, or the like.

FIG. 7 is a schematic diagram showing a build-up welding means for ribs. As shown in this figure, the rib has a pair of contact plates 5 arranged on the inner surface of the steel pipe 11 at an interval, and the pair of contact plates 5 are moved relative to the inner surface of the steel tube 11 in the circumferential direction. And can be formed by overlay welding between the contact plates.
When it is desired to form a spiral protrusion on the inner surface of the steel pipe 11, the steel pipe 11 is moved in the axial direction of the steel pipe 11 while the contact plate 5 is moved relative to the inner surface of the steel pipe 11 in the circumferential direction. Alternatively, the contact plate 5 and the welding torch may be moved in the axial direction of the steel pipe 11.
Further, the protrusion can be formed continuously or intermittently.
Thus, by arranging the pair of contact plates 5 on the inner surface of the steel pipe to form the build-up welding ribs, the size of the ribs, the interval between the ribs, the protruding height of the ribs, and the like can be freely set. .
The rib forming means is not limited to overlay welding, and a ring-shaped member that has been processed into a predetermined shape in advance may be welded to the inner surface of the steel pipe 11, or the conventional method may be applied to the lower portion of the steel pipe having a smooth inner surface. A ribbed steel pipe may be welded.
Moreover, this invention is applicable also when a protrusion is formed in the outer side of a steel pipe.

2A is an overall configuration diagram of the steel pipe of FIG. 1, and FIG. 2B is an enlarged view of a portion A thereof.
This figure has shown the state which formed the rib 13 in the inner surface of the steel pipe 11 of the part corresponded to the joint part 18 by the said 1st Embodiment.
Spacing p of the ribs is to a 100 mm ± 10 mm, the ribs of the number _{n d} (number protrusion strip) or rib projecting height _{h e} (projections effective height), by equation (1) (2) [Expression 1] Then, the number of ribs and the protruding height of the ribs corresponding to the required allowable strength are set.

なお、［数１］は、リブを設定する際の式の一例である。
式（１）によって、算出される値Ｗが、必要とされる許容耐力以上になれば良く、地盤状況や建物の規模に応じて必要とされる許容耐力を別途算出し、それに応じて鋼管径や鋼管厚、突起条数、突起有効高さを変えながら、最適な形状を決定する。
なお、上式は長期許容耐力に対する算定式であり、短期許容耐力に対応させる場合は、許容耐力の数値を１．５倍として算定する。

[Equation 1] is an example of an equation for setting a rib.
It is only necessary that the value W calculated by the equation (1) is equal to or greater than the required allowable strength, and the required allowable strength is calculated separately according to the ground conditions and the scale of the building, and the steel pipe diameter is accordingly calculated. The optimum shape is determined while changing the steel pipe thickness, the number of protrusions, and the effective height of protrusions.
The above formula is a calculation formula for the long-term allowable strength. When the short-term allowable strength is to be used, the numerical value of the allowable strength is calculated as 1.5 times.

FIG. 8 is a schematic diagram showing the cross-sectional shape of the rib. As shown in this figure, the first annular rib 13 (and the second annular rib to be described later), the height h _e is more than 6mm, the width B is 5mm or more, the angle between the inner or outer surface of the side and the steel pipe α It is preferable to have a curved projection having a straight line part on the side part and a curved part on the upper part.

  According to the above-mentioned on-site cast steel pipe concrete piles, subtle proof stress can be adjusted by changing the number of ribs (the number of turns if the ribs are spiral) and the protruding height of the ribs (protrusion effective height). Design freedom is improved. In other words, it is possible to design economically according to the ground conditions and the scale of the building.

  Furthermore, since the annular rib 13 on the inner surface of the steel pipe has a mountain-shaped cross section, even if the concrete 16 is launched from the bottom of the pile hole, the filling of the concrete is not impaired, and the mixture of the concrete and the hole wall stabilizing liquid is formed. The influence of the corner of the groove between the protrusions that are likely to stay is small, and the influence on the adhesion between the concrete and the steel pipe can be suppressed.

  In addition, if the mountain-shaped annular rib 13 on the inner surface of the lower part of the steel pipe is used as a build-up welding projection, not only the thickness and diameter of the steel pipe, but also the interval, shape and number of ribs (if the rib is spiral) The number of turns) can be changed according to the required strength conditions, and the strength can be set according to the ground conditions, improving the degree of freedom of design such as economical design.

FIG. 3 is a second embodiment of the in-situ steel pipe concrete pile according to the present invention. In this example, the in-situ steel pipe concrete pile of the present invention further has a plurality of second pile main bars 21.
The lower end of the second pile main reinforcement 21 is fixed to a part or all of the plurality of first pile main reinforcements 14 and extends to the footing 1.

The second pile main bar 21 is preferably a continuous pile main bar integrated with the first pile main bar 14, but may be joined using a lap joint or may be firmly joined by welding or the like. Moreover, the 2nd pile main reinforcement 21 may be more than the 1st pile main reinforcement 14, and it is good to extend the lower end of the reinforcing bar to the level of the lower end part of a steel pipe in that case.
With this configuration, by extending the pile main bar of the lower pile 3, it is possible to increase the yield strength of the upper pile and strengthen the stress transmission from the footing 1 to the lower pile 3 via the pile upper 10. It can be used to increase the burden.

FIG. 4 is a diagram showing a third embodiment of the in-situ steel pipe concrete pile of the present invention, and FIG. 5 is a configuration diagram of the steel pipe of FIG.
In this example, the cast-in-place steel pipe concrete pile of the present invention further includes a plurality of second annular ribs 23 and a plurality of third pile main bars 24.
The second annular rib 23 has a mountain shape in cross section, and is formed on the inner surface of the upper end portion of the steel pipe 11 with an interval in the axial direction. The second annular rib 23 is substantially the same as the first annular rib 13 described above.
The third pile main bar 24 extends from the footing 1 to the inside of the upper end portion of the steel pipe 11 inside the second annular rib 23.

With this configuration, the stress transmission from the footing 1 to the pile upper part 10 can be further strengthened, and can be used when increasing the stress load on the pile.
The third embodiment has ribs 23 on the upper portion of the steel pipe 11, but, like the first embodiment, the number of ribs (the number of windings if the ribs are spiral) and the protruding height of the ribs (projection effective) By changing the height), it is possible to adjust the proof stress delicately, which improves the degree of freedom in design.
Furthermore, the annular ribs 13 and 23 on the inner surface of the steel pipe have a height of 6 mm or more, a width of 5 mm or more, the angle formed between the side part and the inner or outer surface of the steel pipe is 60 ° to 90 °, and has a straight part on the side part. However, since the upper part has a curved protrusion, the corner of the groove between the protrusions does not impair the filling of the concrete and the mixture of the concrete and the hole wall stabilizing liquid tends to stay in the concrete. There is little influence of a part and the influence with respect to the adhesive force of concrete and a steel pipe can be suppressed.

FIG. 6 is a diagram showing a fourth embodiment of the on-site steel pipe concrete pile according to the present invention. In this example, the cast-in-place steel pipe concrete pile of the present invention further has a plurality of fourth pile main bars 26. As for the 4th pile main reinforcement 26, a lower end is fixed to a part or all of a plurality of 1st pile main reinforcement 14, an upper end is fixed to a part or all of a plurality of 3rd pile main reinforcements 24, and the whole makes the inside of a steel pipe vertical. It extends.
The fourth pile main bar 26 is preferably a continuous pile main bar integrated with the first pile main bar 14 and the third pile main bar 24, but may be joined using a lap joint or firmly joined by welding or the like. Also good. Moreover, the 4th pile main reinforcement 26 may have more 1st pile main reinforcement 14 and the 2nd pile main reinforcement 21, and it is good to extend the lower end of the reinforcing bar to the level of the lower end part of a steel pipe in that case. .
As in the second and third embodiments, this embodiment is used when the stress transmission from the footing to the pile upper part 10 is further strengthened, the proof stress of the pile upper part is increased, and the stress load on the pile is further increased. be able to.
In 2nd Embodiment thru | or 4th Embodiment, although not shown about 2nd pile main reinforcement thru | or 4th pile main reinforcement, a cyclic | annular reinforcing bar is arranged for positioning of a pile main reinforcement. In addition, the second pile main bar to the fourth pile main bar also do not prevent the hoop bars from being appropriately disposed in the same manner as the first pile main bar.
In the embodiment of the present invention, the fixing bars 12 are fixed to the outer peripheral surface or inner peripheral surface of the steel pipe by welding or bolts, but are limited in consideration of workability. The fixing position 12 may be on both the outer peripheral surface and the inner peripheral surface, and the fixing method is not limited to welding or bolt fixing.

As described above, according to the configuration of the present invention, a plurality of first annular ribs 13 having a mountain-shaped cross section are formed on the inner surface of the lower end portion of the steel pipe 11, and the concrete located on the inner side thereof has a lower pile portion. Since so-called reinforcing bar rods composed of a plurality of first pile main bars 14 and a plurality of hoop bars 15 extending from 3 to the lower end of the steel pipe are formed, the first annular rib 13 is connected to the pile upper part 10 and the pile lower part 3. By setting the shape and the number of strips (corresponding to the number of windings when the rib is spiral) to correspond to the proof stress required for the joint 18, sliding between the steel pipe 11 and the concrete 16 is prevented, and the steel pipe Stress transmission between reinforced concrete can be ensured.
In addition, since the first annular rib 13 can be freely set in shape and number of strips (when the rib is spiral) by overlay welding or other means, the design freedom is high and the cost can be reduced.
Further, the first annular rib 13 has a height of 6 mm or more, a width of 5 mm or more, an angle formed between the side portion and the inner surface or the outer surface of the steel pipe is 60 ° to 90 °, and has a straight portion on the side portion. Because of the curved shape of the projections, the effect of the corners of the grooves between the projections does not impair the filling of the concrete and the mixture of the concrete and the pore wall stabilizing liquid tends to stay in the concrete during casting. There are few, and the influence with respect to the adhesive force of concrete and a steel pipe can be suppressed.

  In addition, this invention is not limited to embodiment mentioned above, For example, it can apply also in the case of the pile which has a processus | protrusion on the outer side of a steel pipe, For example, it can change variously, unless it deviates from the summary of this invention. It is.

It is a 1st embodiment figure of a spot cast steel pipe concrete pile of the present invention. It is a block diagram of the steel pipe of FIG. It is 2nd Embodiment figure of the spot cast steel pipe concrete pile of this invention. It is a 3rd embodiment figure of a spot cast steel pipe concrete pile of the present invention. It is a block diagram of the steel pipe of FIG. It is a 4th embodiment figure of a spot cast steel pipe concrete pile of the present invention. It is a schematic diagram which shows the build-up welding means of a rib. It is a schematic diagram which shows the cross-sectional shape of a rib. It is a figure which shows an example of the conventional spot cast steel pipe concrete pile. It is explanatory drawing of the "pile head coupling | bonding method using a cage wire" of patent document 1. FIG. It is a block diagram of the "pile head structure of a cast-in-place steel pipe concrete pile" of patent document 2. FIG. It is a block diagram of the "place cast steel pipe concrete pile" of patent document 3.

Explanation of symbols

1 footing, 3 pile lower part, 5 backing plate,
10 upper piles, 11 steel pipes, 12 anchors,
13 1st annular rib, 14 1st pile main reinforcement, 15 Hoop reinforcement,
16 concrete, 18 joints,
21 second pile main bar, 23 second annular rib,
24 Third pile main bar,
26 4th pile main reinforcement,

Claims (7)

An in-situ steel pipe concrete pile consisting of a steel pipe concrete pile upper part and a reinforced concrete pile lower part,
The upper part of the pile is a steel pipe that extends vertically and has a smooth inner surface, a plurality of fixing bars that are fixed to the upper outer peripheral surface or inner peripheral surface of the steel pipe by welding or bolts and extend into a reinforced concrete footing, and the inner surface of the lower end of the steel pipe A plurality of first annular ribs having a mountain-shaped cross section formed at intervals in the axial direction, and a plurality of first pile main bars extending from the bottom of the pile to the inside of the lower end of the steel pipe inside the first annular rib; An on-site steel pipe concrete pile characterized by comprising a plurality of hoop bars orthogonal to and surrounding the first pile main bar and concrete continuously filled from the upper end to the lower end in the steel pipe.   2. The cast-in-place steel pipe concrete pile according to claim 1, further comprising a plurality of second pile main bars having lower ends fixed to part or all of the plurality of first pile main bars and extending to the footing. .   Further, a plurality of second annular ribs having a mountain-shaped cross section formed on the inner surface of the upper end portion of the steel pipe at an interval in the axial direction, and extended from the footing to the inside of the upper end portion of the steel pipe inside the second annular rib. The in-situ steel pipe concrete pile according to claim 1, comprising a plurality of third pile main bars.   A lower end is fixed to part or all of the plurality of first pile main bars, an upper end is fixed to part or all of the plurality of third pile main bars, and a plurality of fourth pile main bars extending in the steel pipe are provided. The cast-in-place steel pipe concrete pile according to claim 3.   The first annular rib and / or the second annular rib is characterized in that the shape and the number of strips (the number of turns when the rib is spiral) are set so as to correspond to the proof stress necessary for the joint portion. The cast-in-place steel pipe concrete pile according to any one of claims 1 to 4.   The first annular rib and / or the second annular rib are arranged such that a pair of contact plates are arranged at an interval on the inner surface or outer surface of the steel pipe, and the pair of contact plates are moved relative to the inner surface or outer surface of the steel pipe. The spot cast steel pipe concrete pile according to claim 5, wherein the pile is a build-up weld rib formed by build-up welding between the contact plates. The first annular rib and / or the second annular rib has a height of 6 mm or more, a width of 5 mm or more, an angle formed between the side portion and the inner surface or outer surface of the steel pipe is 60 ° to 90 °, and a linear portion on the side portion. The cast-in-place steel pipe concrete pile according to claim 6, further comprising: a curved projection having a curved upper portion.

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