JPS5830449B2 - PC stake - Google Patents

Description

[Detailed description of the invention] The present invention has a reduced number of parts and is easy to manufacture by devising the shape of a stopper for preventing release of prestress that is fixed to an irregularly shaped PC steel plate embedded in a hollow PC pile. Moreover, the present invention provides a PC pile that has extremely high strength when attached to a PC steel bar, and can effectively prevent release of prestress when the concrete pile head portion is crushed.

Apply the required tensile force to PC steel materials such as PC steel rods, PC steel wires, and P0 steel strands, peel them, and pour concrete. After the concrete hardens, the tensile force on the PC steel materials is released to introduce prestress into the concrete. PC piles fabricated by the prestressing method have submerged strength properties compared to older (non-prestressed) prefabricated concrete piles.

However, in foundation work using PC piles, in order to integrate PC pile A and foundation footing B, as shown in Figure 1 A, C, and C, the pile head concrete portion of PC pile A is approximately 1.
PC steel material 1, which is the main reinforcement of PC pile A, was lifted by about 1.
A pile cap processing method is usually adopted in which the pile head is removed and used as an anchor to the foundation footing B.

For this reason, by peeling off the concrete part of the pile head, the adhesion between the PC steel material 1 and the concrete 2 is separated, the prestress is released, and the bending resistance of the concrete 2 part near the pile head treatment area is increased. Shear resistance etc. decrease significantly, which may become a factor in damage caused by earthquakes.

In other words, if we consider the case where the concrete part of the pile head is removed and fixed to the footing, even if it is assumed that it is a pile head pin in the design, it will not work in the event of an earthquake as far as we judge from the general construction specifications. When considering the destruction mechanism, first,
When the pile head is fixed and resists the horizontal force, the balance gradually collapses, and finally, by the time the pile reaches a pin state, the pile head at the bottom of the footing has already been destroyed, and although there are differences in size, it is a kind of damage. It is certain that this is a major factor in causing uneven subsidence.

The greater the earthquake force, the more severe the destruction of the pile head.
The prestress is released in the deep part 1 as the pile head fracture progresses, and it has the potential to develop into an unexpected catastrophe.

For example, the damage to PC piles caused by the recent Miyagi Prefecture Earthquake is considered to be a particularly representative example of this.

In addition, as a means to prevent prestress from being released when the concrete part of the pile head is lifted off, as seen in Japanese Patent Publication No. 11412/1983, a fixing plate with legs protruding from the four corners of the plate is used. With U-shaped bolts facing each other,
Insert both ends of the U-shaped bolt into the fixing plate, intersect the legs of the fixing plate and the U-shaped port to sandwich the PC steel strands, and screw the nuts onto the U-shaped bolts to connect the fixing plate to the PC. Stoppers fixed to stranded steel wire have been proposed in the past.

However, each stopper has a fixing plate,
It requires many parts such as a U-shaped bolt and nuts that are screwed onto both ends of the U-shaped bolt.In addition, the fixing plate is fitted onto the PC@stranded wire, the U-shaped bolt is temporarily inserted into the fixing wire, and the nuts are screwed onto both ends of the U-shaped bolt. Since many installation processes such as screwing together the PC piles are required, manufacturing of PC piles becomes extremely troublesome.

Moreover, since U-shaped bolts essentially only make point contact with the PC steel strands, when applied to hollow-shaped PC piles that introduce strong prestress using PC steel bars, U-shaped bolts
It is clear that slippage occurs between the shaped bolt and the PC steel rod, and this slipping cannot be prevented no matter how much the nut is screwed in.

The present invention achieves the following by devising the shape of the stopper.
These problems were solved all at once, and the sleeve was partially open in the circumferential direction, and a sleeve with a partially open circumferential direction was attached to an irregularly shaped PC steel bar embedded in a hollow PC pile, and a sleeve was installed radially outward from one end in the axial direction. The present invention is characterized in that a stopper consisting of a supporting force that is bent in the opposite direction and that is open in the same phase as the open portion of the sleeve is fitted onto the sleeve, and the sleeve is crimped to the PC steel plate.

According to the configuration, the stopper is a single member, the number of parts is small, and the sleeve and bearing pressure are partly open in the circumferential direction, so that the stopper is a single member and the number of parts is small. Even when tension is applied to the prestressed steel bale by wrapping a shaped rebar around it, it can be easily fitted onto the prestressed steel bale, and the operation is simple and speedy by simply holding the sleeve with a crimping jig that uses hydraulic pressure, etc. Since the stopper can be fixed using the method, it is easy to manufacture PC piles.

In particular, since this fixation is performed by crimping the sleeve, the sleeve and the PC steel rod are in surface contact, and a part of the sleeve that has been deformed in diameter may be formed by irregularly shaped PC steel such as grooves or intents.
Since the stopper engages with the irregularities on the surface of the steel bar, the fixation of the stopper to the PC steel bar is reliable, and the axial length of the sleeve can be adjusted appropriately depending on the amount of prestress to be introduced by the cut PC'WIJ bar. By simply setting this, the required fixed state can be obtained and slippage between the stopper and the PC steel rod can be completely prevented.

Therefore, it is possible to effectively prevent the prestress from being released when the concrete pile head portion of the PC pile is lifted off.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an example of PCaA according to the present invention, and FIG. 3 shows an outline of its reinforcement state.

1 . . . is a irregularly shaped PC steel bar with grooves or indentations, 2 is prestressed concrete, 3 is a top plate, 4 is a reinforcing band, and 5 is a helical guard reinforcing bar.

6... are stoppers for preventing non-stress release, and a plurality of stoppers are protruded from the pile cap of the PC steel bar 1 over an appropriate length at appropriate intervals.

The present invention provides the stopper 6 as shown in FIG.
A sleeve 10 that is partially open in the circumferential direction and a bearing pressure temporary 7 that is bent radially outward from one end in the axial direction and that is open in the same phase as the open section 11 of the sleeve 10. This stopper 6 is connected to a P0 steel rod 1.
. . , and the sleeve 10 is crimped onto the PC@rod 1 . . . as shown in FIGS. 5 and 6.

The distance and L can be set arbitrarily, for example, as shown in the figure, a pond where a stopper 6 is installed only in the vicinity of the pile head, PC
It may be provided over the entire length of the steel rod 1.

1 can be arbitrarily set in consideration of the slippage length, etc., which differs depending on the type of the PC steel bar 1.

Although the cut-off stopper 6 is attached to all the PC steel pieces 1, it does not necessarily have to be attached to all the pieces, and may be attached to every other piece, for example.

[Brief explanation of the drawing]

Fig. 1 A, C and C are construction process diagrams showing a conventional example, Figs. 2 to 6 show examples of the present invention, Fig. 2 is a partially cutaway front view of a PC pile, and Fig. 3 is a construction process diagram showing a conventional example. A schematic diagram of the reinforcement arrangement state, Fig. 4 is a perspective view of the stopper, and Fig. 5 is a perspective view showing the installation state.
FIG. 6 is a partially cutaway front view in the installed state. DESCRIPTION OF SYMBOLS 1... PC steel shell, 6... Stroller 7... Bearing plate, 10... Sleeve.

Claims (1)

[Claims] 1 An irregularly shaped PC steel rod embedded in a hollow PC pile,
A stopper consisting of a sleeve with a part opened in the circumferential direction and a bearing plate bent radially outward from one end in the axial direction of the sleeve and with a part opened in the same phase as the opened part of the sleeve. A PC pile, characterized in that the sleeve is fitted onto the PC steel rod and the sleeve is crimped onto the PC steel rod.