JPH0598638A - Ultra-high-bending tenacity pc pile - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a toughness pile having higher bending toughness than conventional prestressed concrete piles. [Structure] A hollow cylindrical shape is prestressed by a vertical streak 11 made of PC steel material embedded in the thickness direction in the longitudinal direction, and lateral restraint streaks 12 are buried in the circumferential direction to form a PC pile. Use a vertical streak 11 having a uniform elongation of 3% or more and an adhesion force to concrete of 30 kg or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high bending toughness PC pile used for the foundation of civil engineering structures and buildings.

[0002]

2. Description of the Related Art Conventionally, as a high bending toughness PC pile of this type, vertical bars made of PC steel material oriented in the vertical direction are embedded in a cylindrical arrangement within the wall thickness of a cylindrical concrete pile body, It has been developed that a vertical prestress is applied, and lateral restraint bars are arranged at a constant pitch in a ring shape or a spiral shape along the outer peripheral surface of the concrete pile main body on the outside of the vertical bar.

The inventor of the present invention previously found that in this type of high-toughness PC pile, the flexural fracture strength increases when the prestress due to the vertical streaks is increased, but in order to sufficiently satisfy the seismic performance against a large earthquake, the bending moment is required. It has been found that it is necessary to increase the plastic deformation capacity for, and when the prestress introduced by the vertical stirrup is increased, the plastic deformation capacity is decreased and the seismic performance is deteriorated. And from this viewpoint, in order to truly improve the seismic performance, high uniform elongation is 3
By using PC steel material of more than 40% as a lateral restraint bar, an ultra-high bending toughness pile having a deformation capacity twice that of the conventional one was developed (JP-A-62-280418).

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the proof stress against bending moment of the above-mentioned ultra-high bending toughness pile.
It is to further enhance the bending stress dispersion as a reliable one.

That is, in general, in concrete structural members such as prestressed concrete and reinforced concrete, bending cracks occur on the tensile side due to the action of bending moment. Furthermore, when the bending moment is increased, the number of bending cracks increases, and the length of bending cracks that have already occurred also increases.

When the bending moment is further increased, the strain at the outermost end (compression edge) of the concrete on the compression side of the member reaches the flexural compressive fracture strain of the concrete, and the concrete undergoes compressive fracture on the compressive side, leading to the flexural fracture of the member. .. Immediately before that, any one of the plurality of bending cracks generated in the part subjected to uniform bending has a larger opening width than the other cracks, and the bending deformation immediately before fracture is due to this cracking. Focus on the location.

The concentration of bending deformation immediately before bending failure of such a member is particularly remarkable when the interval between cracks is large, that is, when the number of bending cracks occurring within a certain member length range is small. It became clear by an experiment by the present inventor.

In the conventional PC pile, a technique for improving the bending toughness has been developed by using the lateral restraint bar as described above. However, even if the bending deformation ability can be greatly increased, the deformation of the member until breaking is large. Only then, the above-mentioned concentration of bending deformation becomes more and more remarkable, and the member deforms into a bent state at the bending deformation concentrated portion. Such abnormal bending deformation concentration is due to the lateral restraint effect of concrete by the lateral restraint bar, that is,
The problem still remains that the effect of improving (increasing) the compressive deformation capacity of concrete due to lateral restraint is significantly impaired, and thus the effect of improving the bending deformation capacity of the member is also impaired.

Therefore, the present invention provides an ultra-high bending toughness pile having higher bending toughness than the conventional PC pile by preventing such bending deformation concentration.

[0010]

The features of the present invention for solving the above-mentioned conventional problems and achieving the intended purpose are as follows.
A pre-stress is given by a vertical bar made of a PC steel material having a hollow cylindrical shape and embedded in the wall in the longitudinal direction, and a large number of rings are formed in the circumferential direction between the vertical bar and the outer peripheral surface. Alternatively, in a super-high bending toughness PC pile provided with horizontal restraint bars arranged in a spiral shape, the uniform elongation of the vertical bars and the horizontal restraint bars is 3% or more, and the adhesive force of the vertical bars to concrete is 30 kg or more. There is something.

[0011]

In the ultra-high bending toughness pile of the present invention, the adhesive strength of vertical streaks to concrete is set higher than 30 kg, so that the bending deformation of the pile just before bending failure is not concentrated in one place, but the whole area is increased. As a result, the lateral restraint effect of the PC pile using the PC steel material having a large uniform elongation is sufficiently exhibited, and a large bending toughness is obtained.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

1 and 2 show an example of a PC pile according to the present invention. This PC pile has a large number of PCs in the axial direction within the wall thickness of the cylindrical concrete pile body 10.
The vertical bars 11, 11 ... Made of steel are inserted in a cylindrical arrangement, and a spiral horizontal restraint bar 12 oriented in the circumferential direction is embedded near the outer peripheral surface of the pile body on the outer side thereof.

A spacer 14 is provided outside the lateral restraint muscle 12.
The supporting rods 13 and 13 which are fixed to each other are arranged along the outer periphery of the pile body 10 in the longitudinal direction thereof.
The lateral restraint muscles 12 are positioned by 3, 13, .... In the figure, reference numerals 15 and 15 denote iron plates fixed to both ends of the pile body 10.

In this PC pile, vertical prestress is introduced into the pile main body 10 by means of the pretensioning method with the vertical ribs 11, 11 ... A material with a uniform elongation of 3% or more is used.

As shown in FIG. 3, a deep annular or spiral groove 11a is formed on the outer periphery of the vertical streak 11, and the groove 11a has an adhesion force of 30K to concrete.
It is used with more than g.

In addition to the above, the vertical streak 11 has a shape in which a corrugated linear ridge is integrally formed on the outer periphery, and the height of the ridge is made higher than that of the conventional product to enhance the adhesion to concrete. Various shapes such as ones can be used.

Explaining an example of manufacturing this PC pile,
As shown in FIG. 4, the lateral restraint bar 12 is supported inside the bar member 13 and is arranged in the form frame 16. At the time of this bar arrangement, a required number of concrete spacers 14 are fixed to each bar member 13 so as to be separated from the inner surface of the mold 16 by a predetermined distance. In addition, the vertical reinforcements 11 made of PC steel are inserted into the lateral restraint reinforcements 12 in the required number of axial directions. Each vertical reinforcement 11 is cut into a predetermined length, for example, and then male threads are engraved on both ends thereof. Use what you did.

After the bars 11, 12 and the bar member 13 are housed in the mold 16, the end iron plates 15 are installed inside the both ends of the mold 16. After that, both ends of the bar member 13 and the vertical bar 11 are inserted into the through holes of the pair of tension support fittings 17 and 18, and the fixing nut 11b is screwed to the male screw on each end of each vertical bar 11 on the outside thereof. To do.

Then, one of the tension support fittings 17 is attached to the form 16
While supporting it at the end of the
Is movably inserted into the frame 16, a pulling rod 19 is connected to the center of the frame 16, and a fixing plate 20 is screwed onto a male screw 19a formed on the outside of the rod 19.
The end of the form 16 is supported by (as shown in FIG. 5).

Next, a jack (not shown) is set on the end of the form 16, and one tension support metal fitting 18 is pulled through the rod 19 to tension the longitudinal muscle 11 and pull force for prestressing. give.

After the tension is applied in this manner, the fixing plate 20 is rotated and moved until the peripheral surface thereof comes into contact with the end face of the mold 16, and then the tension caused by the jack is released, and the mold 16 is released.
Apply a reaction force to the end of and remove the jack.

Then, the mold 16 is filled with a required amount of concrete 21 by a conventional method, and it is molded into a cylindrical mold by a centrifugal molding machine, and after the necessary curing treatment, it is demolded.

[0024]

As described above, in the present invention, the uniform elongation is 3% or more, and the concrete adhesion is 30K.
By using PC steel material of g or more,
The toughness is significantly higher and the earthquake resistance is significantly improved as compared with the case of using the PC steel material having a concrete adhesion of 20 kg.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a PC pile according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a side view of an example of a PC steel material used for the PC pile of the present invention.

FIG. 4 is a cross-sectional view showing a bar arrangement state in a manufacturing process example of a PC pile of the present invention.

FIG. 5 is a cross-sectional view showing a concrete pouring state of the above.

[Explanation of symbols]

 10 Pile Main Body 11 Vertical Bar 11a Groove 11b Nut 12 Lateral Restraint Bar 13 Bar 14 Spacer 15 End Iron Plate 16 Form 17,17 Tension Bearing Metal 19 Rod 20 Anchoring Plate 21 Concrete

Claims (1)

[Claims] 1. A prestress is imparted by a vertical bar made of a PC steel material having a hollow cylindrical shape and embedded in the wall in the longitudinal direction, and a circumferential direction is provided between the vertical bar and the outer peripheral surface. In a super-high bending toughness PC pile having a large number of ring-shaped or spirally arranged horizontal restraint bars, the uniform elongation of the vertical bars and the horizontal restraint bars is 3% or more, and the vertical bars are attached to the concrete. Ultra-high bending toughness PC pile characterized by having a force of 30 kg or more.