JP5420392B2 - Pile head structure of steel pipe concrete pile - Google Patents

Description

  The present invention can reliably transmit the force from the pile head rebar to the steel pipe concrete pile, and can also increase the proof strength of the pile head, even if an excessive horizontal force is applied, The present invention relates to a pile head structure of a steel pipe concrete pile that can suppress the head from being destroyed and also has good manufacturability of the steel pipe concrete pile.

  A steel pipe concrete pile mainly consists of a steel pipe covering the outer peripheral surface, concrete covered with the steel pipe, and an end plate whose outer peripheral edge is welded to the end of the steel pipe at the pile head. , Provided on the upper surface of the end plate. Unlike PHC piles, steel pipe concrete piles, such as PC steel wires, do not have members that constrain the end plate, so the force acting on the pile head reinforcement is directly transmitted to the pile itself via the end plate. It will be.

  When a pile head reinforcing bar is provided on the upper surface of the end plate, the end plate is structurally in the form of a “cantilever”. The pile head of a steel pipe concrete pile only connects the end plate to the steel pipe and is not designed to function as a rigid body, so if force is applied to the pile head rebar, the steel pipe and end plate As a result, a bending moment is generated with the joint portion as a fulcrum. As a result, the end plate and the steel pipe are deformed, and the force from the pile head reinforcement cannot be sufficiently transmitted to the pile itself.

  Patent document 1 and patent document 2 are known as a structure of this kind of steel pipe concrete pile. The “concrete pile” of Patent Document 1 embeds a large number of anchor rebars (screw rebars) screwed into a coupler nut and its lower part in the concrete at the pile head portion of the outer steel tube-wound concrete pile. The anchor rebar is screwed into the lower half of the coupler nut, and is integrated with the coupler nut with a predetermined tightening torque by the lock nut. After constructing the pile at the site, after filling the upper half screw hole of the coupler nut with cement grout, epoxy resin, etc., through the seat plate on the top of the pile head, in the upper half screw hole of the coupler nut The pile head coupling rebar (screw rebar) is screwed in and the lock nut is tightened with the seat plate interposed therebetween, so that the pile head coupling rebar and the coupler nut are integrated with a predetermined tightening torque.

  Patent Document 2 “Pile head joint structure between ready-made concrete pile and foundation slab concrete” is a pile head of a ready-made concrete pile composed of a concrete pile body and a steel pipe covering the outside of the concrete pile body. The end steel plates are fixed by welding, and a plurality of irregularly shaped studs are planted on the end steel plates. Moreover, a headed stud, a deformed reinforcing bar, and a rib are provided under the end steel plate.

JP-A-5-306527 JP 11-36326 A

  In patent document 1, it has the structure which connects an anchor reinforcing bar and a pile head reinforcing bar 1: 1 via the coupler nut provided in the seat board lower surface. Even if the number of pile head rebars is increased, the coupler nut used for connection is larger than the diameter of the anchor rebar, so the distance between the pile head rebar and the anchor rebar and the number of installations depends on the number of coupler nuts that can be installed. There was a problem that the specification of the joint structure of the pile head was restricted and was restricted.

  Moreover, since it is a structure which bears the force which acts on a pile head reinforcement to an anchor reinforcement, it is necessary to lengthen the length of an anchor reinforcement from the surface of adhesion strength. Considering the manufacturing stage of piles by centrifugal molding, etc., since the long anchor rebar is formed from the seat plate, there is a concern about the swinging movement of the anchor rebar, so that it does not occur. There were various problems in the manufacturing of piles, such as the need to perform a stop work.

  Moreover, in patent document 2, the stud with a head etc. which bears the force transmitted from the deformed stud for joining on an edge part steel plate etc. are embed | buried in the concrete pile main body directly under an edge part steel plate. When a tensile force from a deformed stud is applied to a headed stud or the like, a crack occurs in the surrounding concrete, and this crack progresses into the concrete pile body.

  Since many headed studs and the like are arranged in the circumferential direction of the pile in accordance with the number of deformed studs, a large number of cracks are generally generated in the concrete pile body directly below the end steel plate. In particular, when the crack progresses toward the inner peripheral surface of the concrete pile body, the inner peripheral surface is not covered at all, and thus there is a possibility that splitting may occur due to the crack.

  Furthermore, the pile head not only bears the bending moment acting on the pile head reinforcement and deformed studs, but also must bear the shearing force caused by an excessive horizontal force such as an earthquake by being embedded in the foundation part such as a footing. I must. However, in any of the patent documents, there is a problem that the structural soundness of the pile head is concerned because it is a structure that resists only by adhesion or fixation with concrete using anchor reinforcing bars or studs with heads. .

  In short, in any of the patent documents, anchor rebars and headed studs, etc. are provided in the form of embedding in concrete directly under the seat plate and end steel plates, so the force from the pile head rebar and deformed studs is piled up. However, the strength of the pile head was reduced, and the pile head could be destroyed by an excessive horizontal force such as an earthquake.

  The present invention was devised in view of the above-described conventional problems, and it is possible to reliably transmit the force from the pile head rebar to the steel pipe concrete pile and to enhance the proof strength of the pile head. It is possible to provide a pile head structure of a steel pipe concrete pile that can suppress the pile head from being destroyed even if an excessive horizontal force is applied, and also has good manufacturability of the steel pipe concrete pile. To do.

The pile head structure of a steel pipe concrete pile according to the present invention is a ring in which a pile head rebar is joined to a pile head of a hollow tubular steel pipe concrete pile whose outer peripheral surface is covered with a steel pipe. It is a pile head structure of a steel pipe concrete pile having an end plate, and is formed in a tubular shape attached to the concrete inner peripheral surface of the steel pipe concrete pile, and one end is fixed to the periphery of the inner peripheral edge of the ring end plate It has a stress transmission member , The said stress transmission member is divided | segmented into the circumferential direction of the concrete internal peripheral surface of the said steel pipe concrete pile .

  Moreover, the pile head structure of a steel pipe concrete pile according to the present invention is provided by joining the steel pipe to the pile head of a hollow tubular steel pipe concrete pile whose outer peripheral surface is covered with a steel pipe, and the pile head rebar is joined. A pile head structure of a steel pipe concrete pile having a ring-shaped end plate, wherein the steel pipe is formed in a tubular shape attached to the concrete inner peripheral surface of the steel pipe concrete pile, and overlapped on the ring-shaped end plate. The flange part fastened to a pile head direction of a pile of a concrete pile was equipped with the stress transmission member formed in the one end part.

  The said stress transmission member is divided | segmented into the circumferential direction of the concrete internal peripheral surface of the said steel pipe concrete pile.

In the pile head structure of a steel pipe concrete pile according to the present invention, the force from the pile head rebar can be reliably transmitted to the steel pipe concrete pile, and the proof strength of the pile head can be enhanced. Even if a horizontal force acts, the pile head can be prevented from being destroyed, and a steel pipe concrete pile can be manufactured well. By dividing the stress transmission member in the circumferential direction of the concrete inner peripheral surface of the steel pipe concrete pile, the amount of steel material can be reduced. Moreover, the space | gap by division | segmentation can be utilized for air extraction at the time of manufacture of a steel pipe concrete pile, and a steel pipe concrete pile can be manufactured with sufficient filling property of concrete.

It is a sectional side view which shows 1st Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a sectional side view which shows 2nd Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a sectional side view which shows 3rd Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a sectional side view which shows 4th Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a sectional side view which shows 5th Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a top view of 5th Embodiment shown in FIG. It is a sectional side view which shows 6th Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a sectional side view which shows 7th Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention. It is a top view of 7th Embodiment shown in FIG. It is a sectional side view which shows 8th Embodiment of the pile head structure of the steel pipe concrete pile which concerns on this invention.

  EMBODIMENT OF THE INVENTION Below, suitable embodiment of the pile head structure of the steel pipe concrete pile concerning this invention is described in detail with reference to an accompanying drawing. FIG. 1 shows a first embodiment. As is well known in the art, the steel pipe concrete pile 1 is made of ordinary steel 3 or high-strength concrete or ultra-high-strength concrete by centrifugal molding or the like on the inner side covered with the steel pipe 2 with the steel pipe 2 forming the outer peripheral surface as the outer shell. And is formed in a hollow cylindrical shape. Of course, it is not limited to centrifugal molding, and may be manufactured by a mold, or may be formed in a hollow rectangular tube shape.

  A steel ring-shaped end plate 4 is provided on the pile head of the steel pipe concrete pile 1. The outer peripheral edge of the ring-shaped end plate 4 is welded to the upper end portion of the steel pipe 2. Even if the ring-shaped end plate 4 is positioned on the inner side of the steel pipe 2, the outer peripheral surface 4 a of the outer peripheral edge is abutted against and joined to the inner peripheral surface 2 a of the upper end of the steel pipe 2. The peripheral lower surface 4b may be abutted against and joined to the upper end portion end surface 2b of the steel pipe 2. The width dimension of the ring-shaped end plate 4 is set to a dimension substantially corresponding to the thickness of the concrete 3. A plurality of screw holes 5 are formed through the ring-shaped end plate 4 at intervals in the circumferential direction, and pile head reinforcing bars 6 are screwed into the screw holes 5.

  In the pile head structure of the steel pipe concrete pile according to the first embodiment, the stress transmission member 7 is provided. The stress transmission member 7 is formed of a steel material such as a steel pipe. The stress transmission member 7 is formed in a tubular shape attached to the concrete inner peripheral surface 3a of the hollow tubular steel pipe concrete pile 1 along the circumferential direction thereof. The cross-sectional shape of the stress transmission member 7 is formed in accordance with the cross-sectional shape of the steel pipe concrete pile 1. The tubular stress transmission member 7 constitutes a stress transmission portion continuously in the circumferential direction of the steel pipe concrete pile 1 regardless of the number of pile head reinforcing bars 6 installed. Accordingly, the desired number of pile head reinforcing bars 6 can be installed on the ring-shaped end plate 4.

  The annular stress transmission member 7 is fixed to the periphery of the inner peripheral edges 4c and 4d of the ring-shaped end plate 4 by welding or the like in the tube axial direction ends 7a and 7b. Even if the outer peripheral surface 7a of one end is abutted against and joined to the inner surface 4c of the inner peripheral edge of the ring-shaped end plate 4 so that the stress transmission member 7 is positioned inside the ring-shaped end plate 4, the ring-shaped end plate 4, the upper end surface 7 b of one end may be abutted against and joined to the lower surface 4 d of the inner peripheral edge of the ring-shaped end plate 4.

  The length in the tube axis direction of the stress transmission member 7 is appropriately set so that a necessary stress transmission action can be obtained by adhesion to the concrete inner peripheral surface 3a. Further, the thickness of the stress transmission member 7 is equivalent to the thickness of the steel pipe 2 when the pile head rebar 6 is joined to the center of the ring-shaped end plate 4, and the pile head rebar 6 approaches the steel pipe 2 side. If the pile head rebar 6 is joined close to the stress transmission member 7 side, the thickness is set to be thicker than the steel pipe thickness. Set to

  With this stress transmission member 7, a steel portion covering the concrete inner peripheral surface 3 a is provided on the pile head of the steel pipe concrete pile 1, and the stress transmission member 7, the steel pipe 2, the ring-shaped end plate 4, and the like. The steel structure which has the annular recessed part 8 of the U-shaped cross section which completely surrounds the concrete 3 of a pile head from upper direction and the horizontal direction of both sides is comprised. When producing the steel pipe concrete pile 1, it is preferable to appropriately form an air vent hole (not shown) in the stress transmission member 7 in order to ensure the concrete filling property to the U-shaped cross section.

  Next, the effect | action of the pile head structure of the steel pipe concrete pile which concerns on 1st Embodiment is demonstrated. First, when the steel pipe concrete pile 1 is manufactured, the ring-shaped end plate 4 is welded and joined to the steel pipe 2, and the stress transmission member 7 is welded and joined to the ring-shaped end plate 4 so that an annular recess 8 having a U-shaped cross section is obtained. The steel member provided with is produced. Further, the screw hole 5 of the ring-shaped end plate 4 is plugged so as not to cause a concrete leak or a concrete adherence to the screw hole 5 when the concrete is placed.

  Next, this steel member is set in a centrifugal molding machine, and centrifugal molding is performed while placing the concrete 3. By centrifugal forming, the concrete 3 is cast and filled inside the steel pipe 2 in the form of a hollow cylinder, and the concrete 3 is inflow filled into the annular recess while allowing air to escape from the air vent hole. A steel pipe concrete pile 1 with 7 is manufactured.

  As in the background art, the stress transmission member 7 is not embedded in the concrete directly under the seat plate or the end steel plate, but the one end portions 7a and 7b are fixed around the inner peripheral edges 4c and 4d of the ring-shaped end plate 4. Since it adheres to the concrete inner peripheral surface 3a, it is possible to ensure good concrete filling properties at the time of manufacturing the steel pipe concrete pile 1, and to ensure the structural soundness of the steel pipe concrete pile 1. In addition, the stress transmission member 7 is tubular, and the one end portions 7a and 7b are fixed to the ring-shaped end plate 4 to form a steel member at the time of molding. However, the form is stable as a part of steel members, and the steel pipe concrete pile 1 can be manufactured satisfactorily.

  The steel pipe concrete pile 1 is driven in the field, and the pile head rebar 6 is joined to the ring-shaped end plate 4. Thereafter, a foundation structure such as a footing or a foundation slab is constructed around the steel pipe concrete pile 1. The force acting on the pile head reinforcement 6 is transmitted to the ring-shaped end plate 4. In addition to the steel pipe 2, a stress transmission member 7 that adheres to the concrete inner peripheral surface 3 a is fixed to the ring-shaped end plate 4. Accordingly, the ring-shaped end plate 4 is not cantilevered and is held on the pile head by fixing both ends. For this reason, the force from the pile head reinforcement 6 can be sufficiently transmitted to the steel pipe concrete pile 1. In addition, the concrete inner peripheral surface 3 a can be reinforced by the stress transmission member 7.

  Moreover, since the stress transmission member 7 is not fixed in the concrete directly under the seat plate or the like as in the background art, but is attached to the concrete inner peripheral surface 3a, it does not cause a crack in the concrete 3 inside. The stress can be transmitted from the concrete inner peripheral surface 3 a to the steel pipe concrete pile 1. Therefore, even if an excessive horizontal force such as an earthquake acts as a shearing force on the pile head via a footing or the like, the steel pipe 2, the ring-shaped end plate 4 and the stress transmission member 7 cooperate to bear this. And the strength of the pile head can be increased.

  In short, in the pile head structure of the steel pipe concrete pile according to the first embodiment, the force from the pile head rebar 6 can be reliably transmitted to the steel pipe concrete pile 1 by the stress transmission member 7, and the pile The yield strength of the head can also be increased, and the pile head can be prevented from being destroyed even if an excessive horizontal force is applied.

  FIG. 2 shows a second embodiment. In the second embodiment, a reaction force receiving rebar 9 that transmits stress into the concrete is welded to the outer peripheral surface of the stress transmission member 7 at intervals along the circumferential direction. The reaction force receiving reinforcing bar 9 is formed with a bent portion 9a bent inward of the concrete 3 in the middle portion, and is thereby disposed substantially in the center of the concrete 3 in the thickness direction. The bent portion 9a of the reaction force receiving reinforcing bar 9 is set at a position separated by at least 100 mm from the ring-shaped end plate 4 so that the concrete 3 is not broken immediately below or in the vicinity thereof.

  By providing the reaction force receiving reinforcing bar 9, the length of the stress transmission member 7 in the tube axis direction can be shortened, and the amount of steel material can be reduced. Even in the second embodiment, it is a matter of course that the same operational effects as the above-described embodiment can be obtained.

  FIG. 3 shows a third embodiment. In the third embodiment, a belt-like ring body 10 that is engaged with the concrete inner peripheral surface 3 a is welded to the outer peripheral surface of the stress transmission member 7. The belt-like ring body 10 can enhance the stress transmission action from the stress transmission member 7 to the concrete inner peripheral surface 3a by the bearing pressure due to the cotter action. A plurality of the band-like ring bodies 10 may be provided at intervals in the tube axis direction of the stress transmission member 7.

  Further, instead of the belt-shaped ring body 10, a stud may be provided by projecting outward in the radial direction of the stress transmission member 7 at an interval in the circumferential direction of the stress transmission member 7. Even in the third embodiment, the length of the stress transmission member 7 can be shortened. Even in such a third embodiment, it is a matter of course that the same operational effects as the above-described embodiment can be obtained.

  FIG. 4 shows a fourth embodiment. In the fourth embodiment, the stress transmission member 7 is formed by using a striped steel plate in which irregularities appear on the outer peripheral surface instead of a tubular tube having a smooth outer peripheral surface. Stress is transmitted from the stress transmission member 7 to the concrete inner peripheral surface 3a by the frictional action of the striped steel plate. By using a striped steel plate, the strength of the stress transmission member 7 itself can be increased, and the strength of the pile head can be further increased. Even in the fourth embodiment, the length of the stress transmission member 7 can be shortened. Even in the fourth embodiment, it is a matter of course that the same operational effects as those of the above-described embodiment can be obtained.

  5 and 6 show a fifth embodiment. In the fifth embodiment, a flange portion 7c is formed at one end portion, that is, the upper end portion of the tubular stress transmission member 7 by extending radially outward. The flange portion 7 c is installed so as to overlap the ring-shaped end plate 4. A screw insertion hole 11 is formed in the flange portion 7 c so as to match the screw hole 5 of the ring-shaped end plate 4. By fastening the bolt 12 to the screw hole 5 through the screw insertion hole 11 from the pile axial direction of the steel pipe concrete pile 1, the stress transmission member 7 and the ring-shaped end plate 4 are integrated through the flange portion 7c. Is done.

  In 5th Embodiment, since it is the structure which fastens the stress transmission member 7 to the ring-shaped end plate 4 with the volt | bolt 12, compared with the case where it weld-joins like 1st-4th embodiment, the steel pipe concrete pile 1 of it is. The manufacturing work of the steel member at the time of manufacture can be simplified. In the fifth embodiment, after the steel pipe concrete pile 1 is hit in place, the bolt 12 is removed, and the pile head rebar 6 is screwed into the screw hole 5, so that the flange portion 7 c and the ring-shaped end are formed at the pile head rebar 6. The plate 4 can be integrated.

  In the illustrated example, the case where a striped steel plate is used as the stress transmission member 7 is shown. However, as shown in the first to third embodiments, the steel pipe or the reaction force receiving reinforcing bar having a smooth outer peripheral surface is shown. 9. A belt-like ring body 10 may be provided. Even in the fifth embodiment, it is a matter of course that the same operational effects as the above-described embodiment can be obtained.

  FIG. 7 shows a sixth embodiment. In the sixth embodiment, an annular flange 7d is formed in the other end portion of the stress transmission member 7 of the fifth embodiment, that is, the lower end portion, radially outward to form an annular flange portion 7d. It is embedded in and strengthens the anchor action. In the sixth embodiment, by strengthening the anchoring action, the stress transmission member 7 can be firmly fixed to the concrete 3 against the horizontal force caused by the pulling action of the pile head rebar 6 or an earthquake. The resistance action by can be enhanced. Even in the sixth embodiment, it is a matter of course that the same effects as the above-described embodiment can be obtained.

  8 and 9 show a seventh embodiment. 7th Embodiment presupposes the structure of 5th Embodiment, and divides | segments the stress transmission member 7 in the circumferential direction of the concrete internal peripheral surface 3a of the steel pipe concrete pile 1, and is comprised with the some division | segmentation piece 13. As shown in FIG. It is a thing. By setting it as the division | segmentation piece 13, reduction of the amount of steel materials can be aimed at. Moreover, when manufacturing the steel pipe concrete pile 1, the gap between the divided pieces 13 can be used for air venting, and the steel pipe concrete pile 1 can be manufactured with good filling property of the concrete 3. When the steel pipe concrete pile 1 is manufactured, the screw holes 5 exposed between the divided pieces 13 are plugged. Even in the seventh embodiment, it is a matter of course that the same effects as the above-described embodiment can be obtained.

  FIG. 10 shows an eighth embodiment. In the eighth embodiment, on the premise of the structure of the sixth embodiment in which the annular flange 7d is provided, the stress transmission member 7 is arranged in the circumferential direction of the concrete inner peripheral surface 3a of the steel pipe concrete pile 1 as in the seventh embodiment. It is configured to be constituted by a plurality of divided pieces 13. Even in the eighth embodiment, it is a matter of course that the same effects as the above-described embodiment can be obtained.

  In the first to fourth embodiments, the tubular stress transmission member 7 has been described as an example. However, the stress transmission member 7 of these embodiments is configured by the divided pieces 13 as in the seventh and eighth embodiments. Of course, you may.

  In any of the above embodiments, the case where the pile head rebar 6 is joined to the ring-shaped end plate 4 with a screw has been described as an example, but it goes without saying that it may be welded. In particular, in the fifth to eighth embodiments, the pile head rebar 6 is screwed to the screw hole 5 from which the bolt 12 is removed, but the upper surface of the flange portion 7c between the bolts 12 is removed without removing the bolt 12. The pile head rebar 6 may be welded.

  Moreover, in the said embodiment, although only the stress transmission member 7 was provided, since the concrete 3 of a pile head can be reinforced with the said stress transmission member 7, an anchor effect | action is directly under the ring-shaped end plate 4. FIG. Additional deformed reinforcing bars or headed studs may be additionally provided.

DESCRIPTION OF SYMBOLS 1 Steel pipe concrete pile 2 Steel pipe 3 Concrete 3a Concrete inner peripheral surface 4 Ring-shaped end plate 4c, 4d Around the inner periphery of a ring-shaped end plate 6 Pile head reinforcement 7 Stress transmission member 7a, 7b One end part of a stress transmission member 7c Flange part 13 Split piece

Claims (3)

A pile head structure of a steel pipe concrete pile with a ring-shaped end plate that is installed on the pile head of a hollow cylindrical steel pipe concrete pile with an outer peripheral surface covered with a steel pipe and to which the pile head rebar is joined. There,
It is formed in a tubular shape that is attached to the concrete inner peripheral surface of the steel pipe concrete pile, and includes a stress transmission member in which one end is fixed around the inner peripheral edge of the ring-shaped end plate ,
The pile head structure of a steel pipe concrete pile, wherein the stress transmission member is divided in a circumferential direction of a concrete inner peripheral surface of the steel pipe concrete pile. A pile head structure of a steel pipe concrete pile with a ring-shaped end plate that is installed on the pile head of a hollow cylindrical steel pipe concrete pile with an outer peripheral surface covered with a steel pipe and to which the pile head rebar is joined. There,
A flange portion is formed on the concrete inner peripheral surface of the steel pipe concrete pile, and is overlapped on the ring-shaped end plate and fastened to the pile head of the steel pipe concrete pile in the pile axial direction. A pile head structure of a steel pipe concrete pile characterized by comprising a stress transmission member formed in the section. The pile head structure of a steel pipe concrete pile according to claim 2, wherein the stress transmission member is divided in a circumferential direction of a concrete inner peripheral surface of the steel pipe concrete pile.

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