JP3585134B2 - Prestressed reinforced concrete pile - Google Patents

Description

[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a prestressed reinforced concrete pile suitable for a large-scale structure or a foundation structure in soft ground.
[0002]
[Prior art]
As shown in FIG. 5, this type of conventional prestressed reinforced concrete pile is provided between a plurality of PC steel materials 31 arranged at intervals in the circumferential direction and arranged along the longitudinal direction to resist external force from the lateral direction of the pile. A reinforcing steel cage 30 is formed by arranging a deformed reinforcing steel 32 and winding a spiral reinforcing steel so as to surround the PC steel material 31 and the deformed reinforcing steel 32. The ends of each deformed reinforcing bar 32 are not fixed to the ring-shaped end plate 33, and only the two engaging ends 31 a of each PC steel 31 are hooked into the key-shaped through holes 33 a of the respective end plates 33. . Then, the concrete pile main body 34 was formed by centrifugal molding in a state where the both end plates were pulled together to apply a tension to the PC steel material 31.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional prestressed reinforced concrete pile, since the end of the deformed reinforcing bar 32 is not fixed to the end plate 33, even if the deformed reinforcing bar 32 and the end plate 33 are arranged so that there is no gap, the PC steel 31 , A gap S is generated between the end of the deformed reinforcing bar 32 and the end plate 33. This gap S is 1.25 to 7.5 cm when the length L of the pile is 5 to 15 m and the initial tensile stress of the PC steel 31 is 5,000 to 10,000 kg / cm ² . Since the portion of the gap S of the pile does not have the deformed reinforcing bar 32 and is made of only the PC steel material 31, ductility (toughness, toughness) has been lost, and high performance as a prestressed reinforced concrete pile is maintained. There was no guarantee that This has a significant effect particularly on the design of the pile head, and has the disadvantage that the strength of the pile head is insufficient.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a prestressed reinforced concrete pile in which performance as a prestressed reinforced concrete pile is reliably held up to the pile end and the strength of the pile head can be sufficiently ensured in view of the above-mentioned conventional drawbacks.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a plurality of PC steel materials whose ends are engaged with both end plates arranged at both ends of a concrete pile main body are arranged at intervals in a circumferential direction. and said end plate is disposed to the vicinity of, the prestressed reinforced concrete pile placing the short length deformed bar than concrete pile body between the PC steel of the deformed bar which is located close to the said end plate At least one end is provided with a fixed deformed reinforcing bar whose outer end is fixed to the end plate, and the inner end of the fixed deformed reinforcing bar is overlapped with the deformed reinforcing bar and inserted into the inside of the cylindrical binding metal fitting, said end plate of said between deformed bar and the fixing deformed bars is positioned displaced configured to be able to longitudinally polymerization cohesion joint portion by the bundling fitting upon applying a tension to the PC steel member provided pulled away from each other, Furthermore, only the groove pattern is provided on the surface of the fixed deformed reinforcing bar, and an outer end portion of the fixed deformed reinforcing bar is subjected to heading processing to form an enlarged head having an enlarged outer diameter, and the enlarged head is formed. The parts are fixed to the corresponding stepped holes of the end plate. Further, the gist of the present invention described in claim 2 is that the length of the anchored deformed reinforcing bar is set to two or more types, and the overlapping and binding joint portions of adjacent spliced deformed reinforcing bars are provided at different positions in the longitudinal direction. 1. The prestressed reinforced concrete pile according to 1.
[0006]
[Action]
According to the present invention, a deformed reinforcing bar fixed to an end plate is disposed at least at one end of a deformed reinforcing bar having a length shorter than that of a concrete pile main body, and is superposed on the deformed reinforcing bar and inserted into a tubular binding metal fitting. And, when the tension plate is applied to the PC steel material by separating the both end plates from each other, the deformed reinforcing bar and the fixed deformed reinforcing bar are configured so as to be displaceable in the longitudinal direction by the binding metal fittings, thereby forming a superimposed binding joint portion. By joining to at least one end plate via the overlapping binding joint, the tension is absorbed by the overlapping binding joint, and the tension is prevented from acting on the deformed reinforcing bar itself. The outer end of the fixed deformed reinforcing bar having only the groove pattern on the surface is subjected to heading processing, and the enlarged diameter head whose enlarged outer diameter is formed is fixed to the corresponding stepped hole of the end plate. And by, the strength of the securely prestressed reinforced concrete piles to at least one end portion of the pile is held, makes it also fully guarantee possible for the strength of the pile head.
[0007]
【Example】
Embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, a prestressed reinforced concrete pile according to an embodiment of the present invention is provided with a reinforced cage 1, and the both ends of a plurality of PC steel members 2 constituting the reinforced cage 1 are connected to the concrete pile main body 3. The outer ends of the anchored deformed reinforcing bars 7 which are engaged with the end plates 5 of the joint fittings 4 arranged at both ends, provide the deformed reinforcing bars 9 between the adjacent PC steel materials 2 and have only the groove pattern to be joined to the deformed reinforcing bars 9. The portion is provided with an enlarged diameter head 7b formed by applying a heading process to increase the outer diameter, and the enlarged diameter head 7b is fixed to a corresponding stepped hole 12 of both end plates 5 (only one is shown).
[0008]
The reinforcing cage 1 is composed of a plurality of PC steel materials 2 arranged at equal intervals in the circumferential direction along the generatrix of the cylindrical surface, and a spiral reinforcing bar 8 spirally arranged outside the plurality of PC steel materials 2 on a knitting machine. The spiral rebar 8 is fixed to the outer periphery of the PC steel material 2 by spot welding, and one or two deformed rebars 9 are arranged between the PC steel materials 2 inside the spiral rebar 8. It is made by binding and fixing.
[0009]
The PC steel material 2 has a diameter of 7 mm to 13 mm, and is cut into a predetermined length mainly in consideration of an amount of elongation when tensioned, and each end is subjected to heading by forging to form an engagement end. Is provided with an enlarged diameter head 2b in which the outer diameter is enlarged by bulging. It is assumed that the elongation of the PC steel material 2 under tension is usually 25 mm for a pile length of 5 m and 50 mm for a pile length of 10 m. The heading process by forging is performed, for example, by high-frequency heating the distal end portion of the PC steel material 2 cut to a predetermined length by an induction coil and strongly pressing it by a hammer.
[0010]
As shown in FIGS. 1 and 3, the joint fitting 4 is formed by fixing a reinforcing band 10 to a ring-shaped end plate 5 by welding, and is provided at a position substantially intermediate between the outer periphery and the inner periphery of the end plate 5 in the circumferential direction. A plurality of key-shaped holes 11 for engaging the end portions of the PC steel material 2 at equal intervals, and a plurality of stepped holes 12 for fixing the enlarged diameter head 7b of the fixing deformed reinforcing bar 7 between the key-shaped holes 11. Has been opened.
[0011]
Each key-shaped hole 11 drilled in the end plate 5 has a screw hole 11a and a stepped hole 11b, and is formed by a joint hole 11c slightly larger than the diameter of the PC steel material 2 to be used. Are formed in a direction perpendicular to the radius of the end plate 5, and a concentric counterbore receiving surface 11d is formed outside the circular arc at the end of the elongated hole 11b. The stepped hole 12 has a through hole 12a and a tapered counterbore receiving surface 12c.
[0012]
The deformed reinforcing bar 9 overlaps at least one of the fixed deformed reinforcing bars 7 engaging with the end plate 5 as shown in FIG. 1, and a cylindrical binding metal fitting 15 is attached to the outer periphery of the overlapped portion. The fixed deformed reinforcing bars 7 are joined together by a superposed binding joint 16 formed so as to be displaceable from each other in the longitudinal direction by 15.
[0013]
FIG. 4 is a partial side view showing a main part of the fixed deformed reinforcing bar. The fixing deformed reinforcing bar 7 has a diameter of 13 mm, a length of 600 mm and a length of 900 mm (see FIG. 1) alternately arranged, and has only a spiral groove 7a on its surface over the entire length. As in the case of No. 2, the end portion is provided with a head portion 7b in which the end portion is subjected to heading by forging, and the end portion is bulged to increase the outer diameter. The diameter of the fixed deformed reinforcing bar 7 can be selected from any of 13 mm, 15 mm, 17 mm, and 19 mm.
[0014]
The deformed reinforcing bar 9 has projections on its surface, similar to the “bar steel for reinforced concrete” specified in the Japanese Industrial Standards (JIS G3112). In this embodiment, the ribs 9a of the same size and shape slightly inclined with respect to the circumferential direction are distributed at substantially constant intervals over the entire length.
[0015]
As described above, the fixing deformed reinforcing bar 7 is limited to a groove pattern, and the overlapping and binding joint portion 16 is provided. When one deformed reinforcing bar is used and both ends are fixed to the end plate 5 and tensioned, Since the tension load of the PC steel material 2 is reduced by the amount of the deformed reinforcing bar, and a predetermined prestress is not introduced, it is necessary to adopt a structure in which the tension load acts only on the PC steel material 2. It is.
[0016]
The length L of the superposed binding joint portion 16 is L = 35d or more when the diameter of the fixing deformed reinforcing bar 7 is dmm. Here, 35d is a prescribed required length, and the length of the fixed deformed reinforcing bar 7 is set to 600 mm or more by adding the elongation of the PC steel material 2 under tension and the thickness of the end plate 5 thereto.
[0017]
Further, since the deformed reinforcing bar 9 and the anchoring deformed reinforcing bar 7 are superimposed on each other, the cross-sectional area of the overlapped binding joint portion 16 is large, and the pure cross-sectional area of concrete in this portion is reduced by that much. It should be avoided as much as possible that the plurality of overlapping binding joints 16 are concentrated on the same cross section. Therefore, the two adjacent fixing deformed reinforcing bars 7 have different lengths, and the overlapping and binding joints 16 and the binding metal fittings 15 are arranged with slightly different positions in the longitudinal direction.
[0018]
In addition, when the outer diameter of the prestressed reinforced concrete pile is 300 to 1000 mm, usually, the PC steel 2 is selected from those having a diameter of 9.2, 11 or 13 mm, and the deformed reinforcing bars 9 are named D10, D13, D16, and D19. , D22, D25 or D29.
[0019]
Next, an example of a method for manufacturing a prestressed reinforced concrete pile according to an embodiment of the present invention will be described.
{Circle around (1)} Both ends of the PC steel material 2 cut to a predetermined length are subjected to heading processing to form the enlarged diameter head 2b.
{Circle around (2)} Using a knitting machine, a plurality of PC steel materials 2 are arranged along a cylindrical bus bar and at equal intervals in the circumferential direction, and a spiral reinforcing bar 8 is wound around the entire outer periphery of the plurality of PC steel materials 2. In this state, the respective PC steel materials 2 are fixed to the spiral reinforcing bars 8 by spot welding to form the first reinforcing bar cage 1.
{Circle around (3)} Attach fittings 4 to both ends of the first reinforcing bar 1. This attachment is performed by inserting the engaging end 2a of the PC steel material 2 into the screw hole 11a of the key hole 11 from the inner surface side of the end plate 5, and then moving it along the joint hole 11c to the stepped hole 11b side. .
{Circle around (4)} The deformed reinforcing bar 9 is passed through the first reinforcing bar cage 1 to which the fitting 4 is attached, and the fixed deformed reinforcing bar 7 having the enlarged diameter head 7b at the outer end is stepped from the outer surface side of the end plate 5. The binding metal 15 is inserted into the hole 12 and attached to the outer periphery of the overlapping portion of the fixed deformed reinforcing bar 7 and the deformed reinforcing bar 9 to complete the jointed reinforcing bar cage 1. The enlarged diameter head 7b of the fixing deformed reinforcing bar 7 is fixed to the end plate 5, a jig for manufacturing a pile is fixed to the joint fitting 4 by bolts to prevent loosening, and the fixing deformed from outside the jig. A bolt is pressed against the enlarged diameter head 7b of the reinforcing bar 7 and fixed.
(5) The reinforcing bars 1 are mounted in the formwork, and the end plates 5 are separated from each other by a conventional method while maintaining the postures substantially parallel to each other to apply tension to each PC steel material 2 and concrete therein. The mold is poured, the mold is rotated at a high speed, the concrete pile main body 3 is centrifugally formed, and the concrete is hardened to complete the hollow concrete pile. The concrete pile has a reinforcing bar cage 1 and deformed reinforcing bars 7 and 9 embedded in a wall thickness, and joint fittings 4 are fixed to both ends.
[0020]
The bending test results of the prestressed reinforced concrete pile manufactured as described above showed good results not only for the main body but also for the joint.
[0021]
It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. For example, two or more deformed reinforcing bars 9 can be arranged between the PC steel materials 2. Instead of the cylindrical binding metal 15, a binding wire is wound and bound so that the deformed reinforcing bars can move mutually. Alternatively, after injecting concrete into the formwork, it is also possible to apply a tension to each PC steel material 2 and then centrifuge the hollow concrete pile.
[0022]
It is also possible to use a deformed reinforcing bar having only a groove pattern on the surface as the deformed reinforcing bar 9, and a hole for fixing the enlarged diameter head 7b of the fixing deformed reinforcing bar 7 may be a key-shaped hole. In this case, it is possible to connect the fixing deformed reinforcing bar 7 and the deformed reinforcing bar 9 first with the binding metal fitting 15 and then insert the enlarged diameter head 7b into the key-shaped hole from the inside.
[0023]
【The invention's effect】
According to the present invention, a deformed reinforcing bar having a shorter length than the concrete pile main body is arranged between the PC steel materials, and at least one end of the deformed reinforcing bar arranged near the end plate has an anchoring deformed shape. A reinforcing bar is arranged, overlapped with the deformed reinforcing bar, inserted into the inside of a cylindrical binding metal, and the deformed reinforcing bar and the deformed reinforcing bar are attached by the binding metal when the end plates are separated from each other to apply tension to the PC steel material. By providing a superposed binding joint configured to be displaceable in the longitudinal direction with the anchored deformed reinforcing bar, it is possible to absorb the tension at the superposed binding joint and to prevent the tension from acting on the deformed rebar itself. The outer edge of the fixed deformed reinforcing bar to which the outer end is fixed has only a groove pattern, and the outer end of the fixed deformed reinforcing bar and the end of the PC steel material are subjected to heading processing to increase the outer diameter. Head By making the enlarged heads pass through the corresponding stepped holes of the end plate and closely contact the end plate, the strength of the prestressed reinforced concrete pile is reliably maintained up to the end of the pile, This has the effect that the strength of the head can be sufficiently guaranteed. In addition, in the case of conventional reinforcing bars having a rib pattern and having a projection pattern, a special knitting machine needs to be developed because a projection pattern does not easily pass through a knitting machine when manufacturing a reinforcing bar cage, and a large investment is required. In the present invention, since the deformed reinforcing bar having the projecting pattern is limited only to the inside of the pile body and the deformed reinforcing bar having only the groove pattern at the end is used, a special knitting machine is not required, and the conventionally used knitting machine is used. Can be used to form a reinforced cage. Furthermore, since the fixed reinforcing bar at the end uses a fixed deformed reinforcing bar that has only a groove pattern, it is possible to form a head by heading it, which is compared with a case where the head is fixed using screws, etc. The thickness of the end plate can be reduced, and the deformed reinforcing bar having only the groove pattern is cheaper and more economical than a commercially available PC steel bar, and there is only a thin steel bar with a diameter of up to 13 mm like a commercially available PC steel bar. Inevitably, the required number increases and the work efficiency is reduced. However, there is an advantage that the deformed reinforcing bar having only the groove pattern is thick and has a small work efficiency. According to the second aspect of the present invention, the total length of the pile is provided by setting the lengths of the anchored deformed reinforcing bars to two or more types and providing the overlapping and binding joint portions of adjacent spliced deformed reinforcing bars at mutually different positions in the longitudinal direction. This has the effect that the cross-sectional performance becomes substantially uniform over the range.
[Brief description of the drawings]
FIG. 1 is a partially broken side view of a prestressed reinforced concrete pile according to an embodiment of the present invention, in which a half of concrete on one side of a main part thereof is broken.
FIG. 2 is a plan sectional view taken along line AA of FIG.
FIG. 3 is an omitted plan view showing a main part of an end plate according to the embodiment of the present invention.
FIG. 4 is a partial side view showing an anchored deformed reinforcing bar according to an embodiment of the present invention in a lateral direction.
FIG. 5 is a partial longitudinal sectional view showing a conventional prestressed reinforced concrete pile in a horizontal direction.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 Reinforced basket 2 PC steel material 2 b Expanded head 3 Concrete pile body 4 Joint fitting 5 End plate 7 Anchored deformed reinforcing bar 7 a Groove 7 b Expanded head 8 Spiral bar 9 Deformed bar 9 a Rib 11 Keyed hole 11 b Stepped hole 11 d Seat Counterbore receiving surface 12 Stepped hole 12d Counterbore receiving surface 15 Bundling fitting 16 Stacked binding joint

Claims (2)

A plurality of PC steel end is engaged with the end plates arranged at both ends of the concrete pile body in the circumferential direction at intervals are arranged and disposed to the vicinity of said end plate, length than concrete pile body In a prestressed reinforced concrete pile where deformed reinforcing bars with a short length are placed between each PC steel,
At least one end portion of the deformed bar which is located close to the said end plate arranged fixing deformed bars of the outer end portion is fixed to said end plate, said deformed bar the inner end portion of the fixing deformed bar The deformed reinforcing bars and the fixed deformed reinforcing bars are positioned in the longitudinal direction by the binding bracket when the end plates are separated from each other and inserted into the inside of the tubular binding bracket, and the end plates are separated from each other to apply tension to the PC steel material. An overlapped binding joint portion configured to be displaceable is provided, and furthermore, only the groove pattern is provided on the surface of the anchored deformed reinforcing bar, and the outer end of the anchored deformed reinforcing bar is subjected to heading processing to enlarge the outer diameter. A prestressed reinforced concrete stake wherein a radial head is formed and the enlarged head is fixed to a corresponding stepped hole of the end plate. 2. The prestressed reinforced concrete pile according to claim 1, wherein the length of the anchored deformed reinforcing bar is two or more, and the overlapped and tied joint portions of adjacent joint deformed reinforcing bars are provided at different positions in the longitudinal direction.

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