JPH1136325A - Connection structure of pile head of existing concrete pile and foundation slab concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage and rupture of the pile head of an existing concrete pile, by planting deformed studs on the pile head of the existing concrete pile and providing a structure unsticking the deformed studs from the foundation slab concrete in a relatively short scope from the planted part of the deformed studs. SOLUTION: When a large load acts on deformed studs 5, the pile head 3 of an existing concrete pile 1 is rotated and deformed by the elongation of a part of the deformed studs 5 unstuck from the foundation slab concrete 23 and an effect similar to a pin connection is given and hence the bending moment is reduced. And since the exposed part of the deformed studs is coarse, it is easily stuck to the foundation slab concrete 1. And hence, the deformed studs 5 are easily affected by the foundation slab concrete 23 to easily transfer the axial force and the shearing force and increase the allowable strength of the pile body 2 in an earthquake. Accordingly, the pile head is prevented from damage and rupture and such a ductile connection of the pile head as the studs can yield, can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head joining structure between a ready-made concrete pile and a foundation slab concrete in an implanted reinforcing steel method.

[0002]

2. Description of the Related Art There is a well-known implanted reinforcing method in which an end steel plate is placed on a pile head of a ready-made concrete pile on which a PC steel wire is anchored, and a plurality of reinforcing bars are implanted on the end steel plate. is there. As shown in FIG. 6, this ready-made concrete pile 1 has a substantially long cylindrical pile body 2, an end steel plate 4 fixed to a pile head 3 of the pile body 2, and a plurality of PCs in the pile body 2. It is formed by the steel material 20. This end steel plate 4 is PC
It is a fixing plate of the steel material 20, and the PC steel material 20 is arranged in the pile 2. In FIG. 6, the ready-made concrete pile 1 is buried underground, and the pile head 3 and the end steel plate 4 are thrown away from the concrete 22 to project. In this state, the bar-shaped reinforcing rod 21 is disposed at substantially equal intervals on the exposed upper surface of the end steel plate 4.
Are vertically welded and planted. Then, concrete is poured into the discarded concrete 22 and the foundation slab 23
And at the same time, a joint structure between the ready-made concrete pile 1 and the foundation slab concrete 23 is formed.

In this joint structure, a plurality of reinforcing bars 21 are fixed in a foundation slab concrete 23, and a pile head 3 and an end steel plate 4 are connected to the foundation slab concrete 23 by about 100 mm from the bottom 24 of the foundation slab concrete 23. 23, and the horizontal force is transmitted between the foundation slab concrete 23 and the ready-made concrete pile 1 with the bearing pressure of the implantation portion. The above-mentioned joining structure can be more economically constructed than, for example, a joining structure by a conventional cut-off filling method, and has excellent performance, and thus has been widely used in recent years. Conventionally, since the above-mentioned rebar was responsible for the axial force, an elongated one having a ratio of the nominal diameter to the total length of the rebar of about 40 times was used to enhance the adhesive strength between the rebar and the base slab. Have been.

[0004]

However, in the conventional implanted rebar construction method, the joint between the steel plate at the end of the pile head of the ready-made concrete pile and the plurality of steel bars welded to the steel plate at the end is weak, and the reinforcing bar is somewhat damaged. When the bending moment increases, the joint between the end steel plate and the rebar bends, causing the problem of overturning of the building. As a method other than this, it is desirable to use the pin joint method (joint method that transmits the axial force and shear force but reduces the bending moment) at the joint between the ready-made concrete pile and the foundation slab concrete. This method is costly and not practical. There is also a rigid joining method. However, this method is difficult, and when a load exceeding the permissible proof stress of the pile is applied due to an earthquake or the like, there is a problem that the pile head and the reinforcing bar are damaged or broken.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a pile head joint structure between a ready-made concrete pile and foundation slab concrete, which can prevent damage and destruction of a pile head of the ready-made concrete pile.

[0006]

According to the present invention, there is provided a pile head joining structure between a ready-made concrete pile and a foundation slab concrete, comprising a plurality of deformed studs on an exposed upper surface of an end steel plate provided at a pile head of the ready-made concrete pile. The vertical stud is planted so that the stud and the foundation slab concrete are separated from each other over a relatively short range from the implanted portion of the deformed stud.

Further, as such means, a cylindrical shape is formed over a relatively short range from the implanted portion of the deformed stud, or over a relatively short range from the implanted portion of the deformed stud to the upper surface of the end steel plate. Part and / or a flat body. Alternatively, the nodes and ribs of the irregular stud are removed by cutting over a relatively short range from the implanted portion of the irregular stud. Or, over a relatively short range from the implanted portion of the deformed stud, or up to the upper surface of the end steel plate as well as a relatively short range than the implanted portion of the deformed stud, asphalt,
A synthetic resin or the like is applied. The above basic slab concrete
The range of the structure for cutting off the adhesion between the stud and the deformed stud is set to a range of about 100 mm from the implanted portion of the deformed stud. Further, a deformed reinforcing bar may be used as the deformed stud.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pile head joining structure between a ready-made concrete pile and a foundation slab concrete according to the present invention will be described with reference to FIGS. Reference numeral 1 in the figure denotes a ready-made concrete pile buried in the ground as will be described later, which, like the above-mentioned ready-made concrete pile, has a substantially cylindrical pile 2 and a pile head 3 of the pile 2. And the fixed end steel plate 4. The ready-made concrete pile 1 is buried in the ground, and the exposed upper surface of the end steel plate 4 is formed in a relatively smooth shape with little friction. On the exposed upper surface of the end steel plate 4, a plurality of irregularly shaped studs 5 are vertically stood and welded at substantially equal intervals. In this embodiment, a reinforcing bar is used as the deformed stud 5 (hereinafter 5 is referred to as a deformed reinforcing bar). The deformed reinforcing bar 5 is a reinforcing bar formed in a shape to which concrete can easily adhere, and the ratio between the nominal diameter and the total length is preferably set to about 40 times.

FIGS. 1 and 2 show a first embodiment in which a reinforcing member 7 is provided over a range of about 100 mm from the implanted portion 6 of the deformed reinforcing bar 5 and over the upper surface of the end steel plate 4. . Reinforcement 7 is approximately one to one from implanted portion 6 of deformed reinforcing bar 5.
It comprises a cylindrical portion 8 having a substantially cylindrical shape for covering the deformed reinforcing bar 5 over a range up to about 00 mm, and a flat portion 9 covering the upper surface of the end steel plate 4. Since the surface of the reinforcing member 7 is smooth, it is difficult for the reinforcing member 7 to adhere the foundation slab concrete 23. That is, the reinforcing member 7 does not depend on the foundation slab concrete 23 and reduces the bending moment. On the contrary, since the surface of the deformed reinforcing bar 5 is rough,
The base slab concrete 23 can be easily attached. From this, the deformed reinforcing bar 5 depends on the foundation slab 23, easily transmits the axial force and the shearing force, and the elongation for bending is concentrated on the portion having the reinforcing member 7.

FIGS. 3 and 4 show a second embodiment in which the nodes and ribs of the deformed reinforcing bar 5 are removed by cutting over a range of approximately 100 mm from the implanted portion 6 of the deformed reinforcing bar 5. I have. Also in this case, since the cut portion is smooth, the cut portion 10 is close to the base slab concrete near the implanted portion 6 of the deformed reinforcing bar 5 as in the embodiment shown in FIGS. 23, the bending moment is reduced, and conversely, since the surface of the deformed reinforcing bar 5 is rough, the foundation slab concrete 23 is easily attached.
From this, deformed reinforcing bar 5 is used for foundation slab concrete 2
3 and easy to transmit axial force and shear force,
Elongation for bending concentrates on the part being cut.

FIG. 5 shows that approximately 10 minutes from the implanted portion 6 of the deformed reinforcing bar 5.
A third embodiment in which asphalt is applied over a range up to about 0 mm and the end steel plate 4 is shown.
Also in this case, as in the above embodiment, the asphalt tubular portion 11 does not depend on the foundation slab concrete 23 and reduces the bending moment because the portion to which asphalt is applied does not easily adhere concrete. Since the exposed portion of the deformed reinforcing bar 5 easily transmits the axial force and the shearing force, the elongation for bending is concentrated on the portion coated with asphalt.

It should be noted that approximately 10 from the implanted portion 6 of the deformed reinforcing bar 5
Although the adhesion between the deformed reinforcing bar 5 and the foundation slab concrete 23 is cut over a range of about 0 mm, it is almost 100 m.
It is not necessary to limit to a range of about m, and it is sufficient to perform the range within a range in which the deformed reinforcing bar 5 can be assisted by the tubular portion 8. In the first embodiment, the reinforcing member 7 is provided in a range from the implanted portion 6 of the deformed reinforcing bar 5 to about 100 mm and over the upper surface of the end steel plate 4.
May be provided in a range from the implantation portion 6 to about 100 mm. Further, in the third embodiment, a range of approximately 100 mm from the implanted portion 6 of the deformed reinforcing bar 5 and the
Although asphalt is applied over the upper surface of the asphalt, it is not necessary to limit to asphalt, and a synthetic resin may be used.
Further, the above three embodiments may be used in combination.

In this state, the foundation slab concrete 23 is formed, and at the same time, a pile head joint structure is formed. In this pile head joint structure, a plurality of deformed reinforcing bars 5, end steel plates 4, and a pile head 3 of a ready-made concrete pile 1 are embedded in a foundation slab concrete 23, and this is fixed to the foundation slab concrete 23. On the other hand, the discarded concrete 22 is abutted against the bottom 24 of the foundation slab concrete 23 and arranged to form a pile head joint structure. In the above pile head joint structure,
Even when a large load is applied, the impact can be reduced because the elongation concentrates on the portion of the deformed reinforcing bar 5 where the adhesion of the foundation slab concrete 23 has been cut.

[0014]

According to the present invention, the pile head joint structure between the ready-made concrete pile and the foundation slab concrete is provided by vertically forming a plurality of irregularly shaped studs on the exposed upper surface of the end steel plate provided at the pile head of the ready-made concrete pile. The studs are stood upright and the structure is designed to cut off the adhesion between the studs and the foundation slab concrete over a relatively short area from the studs of the studs. In addition to the above, the extension of the part of the deformed stud that cut off the adhesion with the foundation slab concrete improves the rotation and deformation performance of the pile head of the ready-made concrete pile, and as a result has an effect similar to pin joining , Reduce bending moment. On the other hand, since the exposed portion of the irregular stud is rough, it is easy to adhere to the foundation slab concrete. For this reason, the deformed stud depends on the foundation slab concrete and easily transmits the axial force and the shear force. In other words, the part where the deformed stud is exposed is bonded with high rigidity close to the rigid joint, and the part with the structure to cut off the adhesion between the deformed stud and the foundation slab concrete by actively yielding the deformed stud By using semi-fixed to pin-like joints with high deformation performance (deformation angle of about 1/30), the allowable strength of piles increases due to earthquakes, etc. compared to the conventional pile head joint structure, and the pile head is damaged This has the effect of securing a ductile pile head joint that allows the stud to yield without breaking.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal perspective view showing a first embodiment of a pile head joint structure between a ready-made concrete pile and a foundation slab concrete of the present invention.

FIG. 2 is a vertical sectional front view showing the pile head joint structure shown in FIG. 1;

FIG. 3 is a partially longitudinal perspective view showing another second embodiment of the pile head joining structure between the ready-made concrete pile and the foundation slab concrete of the present invention.

4 is a vertical sectional front view showing the pile head joint structure shown in FIG. 3;

FIG. 5 is a longitudinal sectional front view showing a third embodiment of a pile head joint structure different from that of FIG. 4;

FIG. 6 is a longitudinal sectional front view showing a conventional joint structure between a ready-made concrete pile and a foundation slab concrete.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ready-made concrete pile 2 Pile 3 Pile head 4 Steel plate at end 5 Deformed bar 6 Implantation part 7 Reinforcement body 8 Cylindrical part 9 Flat part 10 Cutting part 11 Cylindrical part 20 PC steel wire 21 Reinforcing steel 22 Discarded concrete 23 Foundation slab concrete 24 bottom

Claims (6)

[Claims] 1. A plurality of irregularly shaped studs are vertically erected on an exposed upper surface of an end steel plate provided at a pile head of a ready-made concrete pile. A pile head joint structure between a ready-made concrete pile and a foundation slab concrete, wherein the structure is designed to cut off the adhesion between the deformed stud and the foundation slab concrete over a relatively short range. 2. A cylindrical portion and / or a relatively short range from the implanted portion of the deformed stud, or a relatively short range from the implanted portion of the deformed stud, to the upper surface of the end steel plate. The pile head joint structure between the ready-made concrete pile and the foundation slab concrete according to claim 1, which is covered by a reinforcing member composed of a flat plate portion. 3. The prefabricated concrete pile and the foundation slab concrete according to claim 1 or 2, wherein nodes and ribs of the deformed stud are removed by cutting over a relatively short range from the implanted portion of the deformed stud. Pile head joint structure. 4. Asphalt, synthetic resin or the like is applied over a relatively short range from the implanted portion of the deformed stud, or over a relatively short range from the implanted portion of the deformed stud to the upper surface of the end steel plate. The pile head joint structure between the ready-made concrete pile and the foundation slab concrete according to any one of claims 1 to 3, which is coated. 5. The structure according to claim 1, wherein the structure that cuts off the adhesion between the foundation slab concrete and the deformed stud is approximately 100 mm from the implanted portion of the deformed stud. Head joint structure between precast concrete pile and foundation slab concrete. 6. The pile head joint structure between a ready-made concrete pile and a foundation slab concrete according to claim 1, wherein a deformed reinforcing bar is used as the deformed stud.