JP2010180641A - End structure of prestressed concrete pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end structure of a prestressed concrete pile capable of solving problem of a conventional one wherein if an unexpected bending tension is applied to a place joined to a pile by a large earthquake, cracks occur in a concrete body at the rib of a reinforcement band, and a structure cannot be stably supported due to the shortage of a bearing force. <P>SOLUTION: This end structure of the prestressed concrete pile includes an end plate 1, a tendon 2, and a concrete body 3. The end plate 1 is formed in a ring shape and radially comprises locking holes 11. The tendon 2 comprises a head part 21 at one end. The head part 21 is locked to the locking holes 11 of the end plate 1 so as to introduce a tension thereto. The concrete body 3 is fitted to the end plate 1 at one end, and extends to the other end while enclosing the tendon 2. The tendon 2 comprises at least one protrusion 22 in the concrete body 3 separately from the head part 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is applied to an end structure of a prestressed concrete pile, and when a bending tensile force is applied to the pile, the load applied to the connecting portion of the pile is reduced, and the conventionally used reinforcing band and sleeve are to be eliminated. Is.

A round head 22 is formed at the end of the PC steel bar 21, and the round head 22 is locked to the seat 13 of the opposing 8-shaped PC steel bar mounting portion 11 of the end plate 10 opposed on the axis. Then, pulling both end plates in opposite directions with a tensioning device to give tension to the PC steel bar 21, placing concrete, after curing and curing the concrete, removing the tensioning device and introducing prestress into the concrete pile JP-A-2002-194737 (Patent Document 1) (see paragraphs [0009], [FIG. 1], [FIG. 3] of the same document).

  Although it is not related to piles, in order to form the prestressed effective area 1a and the ineffective area 1b in the prestressed concrete beam, the fixing hardware 4 and 4 that are paired with the tension material 2 to be buried are bonded by pressure and sandwiched between both fixing hardware. The effective region 1a is formed while the prestress introduced from the beginning is always maintained for the tendon 2 in the region, and the ineffective region 1b is formed between the fixing hardware 4 and the beam end surface. A prestressed concrete beam is disclosed in Japanese Patent Application Laid-Open No. 2004-293179 (Patent Document 2) (see paragraph [0015]).

  In the pretension member, the PC steel material is fixed by adhesion to concrete, and the length necessary for fixing (fixing length) may be 65 times the diameter in the case of a PC steel stranded wire. It is described in the “Road Bridge Method Book / Comment I Common Edition III Concrete Bridge Edition” (Non-Patent Document 1) published by the Japan Road Association in December (5th line to 185 from the bottom of page 183 of the same book) (See “Figure-Solution 4.4.13 Pre-stress distribution of pre-tension members” on page).

  FIG. 4 shows a pile end structure known to the applicant of the present application, and the manner in which the tension member 2 ′ is locked to the end plate 1 ′ is the same as the disclosed technique of Patent Document 1. In the case of FIG. 4, the head 21 ′ of the tension member 2 ′ is locked in the locking groove 11 ′ of the end plate 1 ′, and tension is introduced into the concrete body 3 ′. A reinforcing band B is welded along the end, and the end portion of the concrete body 3 ′ is reinforced by the concave portion B ′ of the reinforcing band to form a pile 4 ′ having a hollow portion 32 ′ inside the wall 31 ′. Also in this case, there is no convex portion on the tension material 2 ′ passing through the inside of the concrete body 3 ′, and no consideration is given to non-fixing of the tension material 2 ′ and the concrete body 3 ′.

JP 2002-194737 A JP 2004-293179 A

December 1996, issued by the Japan Road Association, “Road Bridge Instructions / Explanation I Common Section III Concrete Bridge Section”

  In the invention of Patent Document 1, the round head 22 of the PC steel bar 21 is an 8-shaped PC steel bar of the end plate 10 as means for locking to the end plate 10 in order to introduce tension to the PC steel bar 21. It is formed for engagement with the seat 13 of the mounting portion 11 and is not embedded in the concrete. Therefore, when a bending tensile force is applied to the joint end portion of the pile, the PC steel bar 21 loses the adhesion force with the concrete and extends at this end portion, so that cracking occurs in the concrete.

  In the case of the invention disclosed in Patent Document 2, a pair of fixing hardware 4 and 4 is bonded to a prestressed concrete beam by pressure bonding to the tension member 2 and embedded. The pile is for supporting the axial load, and its length is naturally limited. Therefore, when installing deeply in the ground, the necessary number of piles will be connected and used, but if the connecting part is not rigidly connected, the load support will become unstable, and it can play a role as a pile. Absent. Therefore, in the case of a pile, the prestress is actually introduced along its entire length, and it is impossible to form a prestress ineffective region.

  According to Non-Patent Document 1, the range in which the PC steel stranded wire may become unfixed with concrete when a load is applied is set to a range 65 times the diameter of the PC steel stranded wire. In the case of a pile, since this non-fixed state occurs at the end portion, concrete cracks often occur at the end portion. If cracks occur, the support capacity of the piles is insufficient, which is extremely dangerous, and it is essential to develop means to prevent cracks with reference to this explanation.

  An object of the present invention is to provide an end structure of a prestressed concrete pile in which prestress is introduced to the entire length of the prestressed concrete and is suitable for rigid connection at a connecting portion.

(Claim 1) An end structure of a prestressed concrete pile according to the present invention includes an end plate, a tension material, and a concrete body. The end plate is annular and has locking holes radially. The tension member has a head at one end, and the tension is introduced by locking the head in the locking hole of the end plate. One end of the concrete body is in close contact with the end plate, and the other end of the concrete body is wrapped with the tendon. And this tendon is provided with at least 1 convex part in this concrete body separately from this head.

  The concrete pile is locked to the end plates at both ends with a tension material, and this end plate is pulled with a jack to introduce a tension to the tension material. Therefore, it is common to introduce prestress into concrete, and the concrete body is hollow. In the case of a pile used for driving in the lowermost step, a sharpened plating is provided instead of the end plate. The piles are added as appropriate according to the driving depth. Means such as welding or bolts and nuts are used for the extension.

  When attaching a tension material to an end plate, a tap hole with a taper is drilled in the end plate, and the tension material is inserted into the tap hole and locked to the taper at the head of the end. In the present invention, the tendon includes at least one convex portion separately from the head. The convex portion is located in the concrete body, and when a bending tensile force is applied to the pile, the tension material is not attached to the concrete body at a portion close to the end plate and extends. Stops at the convex part, and takes charge of the force applied to the connecting part by the tension material.

  This prevents the cracks that occur in the concrete body near the end plate when bending tensile force is applied to the pile, and in order to prevent this crack, the reinforcement band that was conventionally welded to the end plate No need for sleeves or sleeves.

(Claim 2) The convex portion of the tendon may be provided in a region where the concrete body is cracked by a bending tensile force acting on the pile.
By doing so, many cracks generated in the concrete body due to the bending tensile force are observed in a region close to the end plate, so that the cracks generated in this region can be effectively prevented.

(Claim 3) The region may be 10 to 40 times larger than the outer diameter of the tendon material on the tendon material from the outer surface of the end plate.
If it carries out like this, a crack can be effectively prevented on the dimension of 10-40 culture | cultivation of the outer diameter of the tension material in which a crack will generate | occur | produce frequently.

(Claim 4) The convex portion may be a hump formed by deformation of the tendon material itself.
In this way, the hump is integrated with the tendon, so that the position does not shift and the extension of the tendon is surely prevented.

(Claim 5) The convex portion may be a head fitted to the tension material.
In this case, since the head is prepared and fitted separately from the tendon, the troublesome work of squeezing the tendon itself can be omitted.

(Claim 6) The end plate may include a side plate covering the outer peripheral surface of the concrete body along the outer peripheral edge.
If it carries out like this, the edge part of a concrete body will be reinforced and even if it receives an impact at this edge part, an edge part will not be missing.

  According to the present invention, the tension member is provided with at least one convex part separately from the head for locking with respect to the end plate, and the convex part is located in the concrete body, so that the bending tensile force is applied to the pile. When the tension acts, the tension material sticks to the concrete at the portion close to the end plate and extends, so that the convex portion can stop the tension material and apply the force applied to the connection portion by the tension material. Therefore, in order to prevent cracks that occur in the concrete body near the end plate when bending tensile force is applied to the pile, it is unnecessary to use a reinforcing band or sleeve that was welded to the end plate. be able to.

  According to claim 2, since the convex portion of the tendon is provided in a region where the concrete body is cracked by the bending tensile force acting on the pile, the bending member is applied to the concrete body and the end plate. It is possible to effectively prevent cracks that occur in a close region.

  According to claim 3, since the region is on the tendon from the outer surface of the end plate and is 10 to 40 times larger than the outer diameter of the tendon, the outside of the tendon that is often cracked. Cracks can be effectively prevented on a dimension 10 to 40 times the diameter.

  According to claim 4, since the convex portion is a hump formed by deformation of the tension material itself, it is integrated with the tension material, and the tension material is surely extended without being displaced. You can stop.

  According to the fifth aspect, since the convex portion is a head fitted to the tension material, the head can be prepared and fitted separately from the tension material, and the troublesome work of pressing the tension material itself can be omitted.

  According to claim 6, since the end plate is provided with a side plate that covers the outer peripheral surface of the concrete body along the outer peripheral edge, the end portion of the concrete body is reinforced, and even if the end portion receives an impact, the end plate is endless. There is no such thing as missing parts.

It is a partial cross section figure which shows the specific example of the relationship between the edge plate 1 employ | adopted for the edge part structure of the prestressed concrete pile concerning this invention, and the latching | locking part of the tension material 2. FIG. It is a partial cross section figure which shows the specific example of the edge part structure of the pile made from prestressed concrete concerning this invention. It is sectional drawing of the edge part structure of the pile connected adjacently up and down. It is a partial cross section figure which shows the edge part structure of the conventional pile made from prestressed concrete. It is a partial cross section figure which shows the structure of the connection part of the conventional prestressed concrete pile.

  1 is an end plate, 2 is a tension material, 3 is a concrete body. The end plate 1 is annular and has locking holes 11 radially. The end plates 1 are opposed to both ends of the cylindrical formwork, and the head 21 at one end of the tension member 2 is locked to the step 12 of the locking hole 11 of the one end plate 1. The end head 21 is locked to the stepped portion 12 of the locking hole 11 of the other end plate 1, and the both end plates 1 are pulled away from each other to introduce tension to the tension member 2. In this state, if the mold is filled with concrete and rotated, the concrete sticks to the end plate 1 or the mold surface by centrifugal force to form a wall 31, and a pile 4 having a hollow portion 32 in the center is formed. Get nervous. The tension material 2 passes through the thickness of the wall 31, and if the end plate 1 is released when the concrete body 3 is solidified, a tension force is introduced into the concrete body 3.

  In the illustrated example, the number of the convex portions 22 that are separate from the head portion 21 of the tendon material 2 is one, but may be two or more, and is within the thickness of the wall 31 of the concrete body 3. Then, when a bending tensile force is applied to the pile 4, the tension material 2 is prevented from being attached to the concrete body 3 and extending at a portion close to the end plate 1 by the one or a plurality of convex portions 22. . Thereby, the force applied to the connection part of the pile 4 can be handled by the tension material 2.

  When a bending tensile force is applied to the pile 4 and the tensile force T acts on the welded portion W of the end plates 1 welded to each other, the tension material 2 tends to extend, but the convex portion 22 stops its elongation. The adhesion between the material 2 and the concrete body 3 is not cut off, and a crack C is prevented from occurring in the concrete body 3 at a portion close to the end plate 1. In the past, in order to prevent this, the reinforcing band B was welded to the end plate 1 so as to surround the concrete body 3 and coped with by the recess B ′ of the reinforcing band B, but this reinforcing band B may be made unnecessary. it can. Similarly, a reinforcing sleeve can be omitted.

(Claim 2) The convex part 22 of the tendon 2 is provided in the area | region 33 where the crack C generate | occur | produces in the concrete body 3 with the bending tensile force which acts on a pile.
In this case, cracks C generated in the concrete body 3 by bending tensile force are often observed in the region 33 close to the end plate 1, so that the generation of cracks C can be effectively prevented.

(Claim 3) The region 33 is on the tendon 2 from the outer surface of the end plate 1 and is 10 to 40 times the outer diameter d of the tendon 2.
In this case, the generation of the crack C can be effectively prevented on the outer diameter of the tension material 2 in which the crack C is often generated.

(Claim 4) The convex part 22 is a hump formed by deformation of the tendon 2 itself.
In this case, since the hump is integral with the tendon 2, the position does not shift and the extension of the tendon 2 can be reliably prevented.

(Claim 5) The convex portion 22 may be a head fitted to the tendon 2.
In this case, since the head is prepared and fitted separately from the tendon 2, the troublesome work of pressing the tendon 2 itself can be omitted.

(Claim 6) The end plate 1 includes a side plate 13 covering the outer peripheral surface of the concrete body 3 along the outer peripheral edge.
In this case, the end portion of the concrete body 3 is reinforced, and even if the end portion is subjected to an impact, the end portion is not lost.

DESCRIPTION OF SYMBOLS 1 End plate 11 Locking hole 12 Step part 13 Side plate 2 Tension material 21 Head part 22 Convex part 3 Concrete body 31 Wall 32 Hollow part 33 Area 4 Pile B Reinforcement band B 'Concave part C Crack

Claims (6)

Including the end plate (1), the tendon (2) and the concrete body (3),
The end plate (1) is annular and has radial locking holes (11),
The tension member (2) includes a head (21) at one end, and the tension (force) is introduced by locking the head (21) in the locking hole (11) of the end plate (1).
One end of the concrete body (3) is in close contact with the end plate (1), and the other end of the concrete body (3) is wrapped and stretched.
The end of a prestressed concrete pile characterized in that the tendon (2) is provided with at least one convex part (22) in the concrete body (3) separately from the head (21). Construction.
The convex portion (22) of the tendon (2) is provided in a region (33) where a crack (C) occurs in the concrete body (3) by a bending tensile force acting on a pile. End structure of prestressed concrete pile.
The region (33) is 10 to 40 times larger than the outer diameter (d) of the tendon (2) from the outer surface of the end plate (1) onto the tendon (2). End structure of prestressed concrete pile.
The end structure of a prestressed concrete pile according to claim 1, wherein the protrusion (22) is a hump formed by deformation of the tendon (2) itself.
The end structure of the prestressed concrete pile according to claim 1, wherein the convex portion (22) is a head fitted to the tendon (2).
  The end structure of a prestressed concrete pile according to claim 1, wherein the end plate (1) includes a side plate (12) covering an outer peripheral surface of the concrete body (3) along an outer peripheral edge.

Images