JPS5821860Y2 - Prestressed concrete tension fixing device - Google Patents

Description

[Detailed description of the invention] This modification relates to an improvement of a tendon tension fixing device used in prestressed concrete construction.

In general, prestressed concrete using tendons such as strands is widely used, and the ends of the tendons are fixed by using a cone with tendon insertion holes through which multiple tendons are inserted, and the tension of the cone is After tensioning the tendons inserted into each of the tension material insertion holes, each tendon is fixed to the cone by inserting a wedge into the tapered wedge-fitting part formed at the outer end of the tension material insertion hole. is already known.

However, when performing secondary tension fixing work with a jack in this type of device, it has conventionally been necessary to have a tension material penetration part between the jack and the bearing plate, and to provide a wedge to loosen the grip of the wedge. A tensioning method has been used in which a jack chair having a movable cavity is used to tension the tension material with a jack.

In such a tensioning method using a jack chair having a tension material penetration part and a gap, the pre-fixed wedge must be pulled out to some extent by pulling the tension material with the jack to release the fixation. When the tension is released, the wedge needs to be drawn into the tapered wedge insertion part again due to the return of the tendon material and fixed. We are currently trying to keep the number of items removed to the minimum necessary.

However, in the conventional device using a presser plate, the presser plate inside the jack chair cannot be operated from the outside, and it has not been possible to completely prevent the tendon from returning after tensioning.

For this reason, heavy tension was applied in anticipation of the return in advance, but in this case, the return of tension varied from wedge to wedge, and there was a drawback that uniform tension could not be obtained.

Therefore, in view of the above-mentioned drawbacks, the present invention has been proposed to achieve almost complete fixation of the tension material by the wedge after the tension material is pulled with a jerk after the primary tension fixation and before the tension by the jerk is released. The present invention provides a prestressed concrete tendon tension fixing device that can minimize or almost completely prevent return.

Next, an example of implementation of the present invention will be described with reference to the drawings.

In the figure, 1 is a concrete structure, 2 is a sheath for inserting tendons, and 3 is a bearing plate embedded in the end face of the concrete structure.

A required number of tension members 4 are inserted into the insertion holes of the bearing pressure plate 2, and each tension member 4 is inserted into the tension member insertion holes 6, 6, . . . formed in the cylindrical cone 5, respectively. has been done.

A thread 7 is cut on the outer periphery of the cone, into which a fixing nut 8 is fixed after the primary tensioning operation of the tendon 4.

The outer ends of the tendon insertion holes 6.6.6... have tapered wedge fitting portions 5a, 5 that widen outward.
a... is formed.

Wedge pieces 8 a and 8 b, each of which has a substantially semi-circular cross-section formed by halving a cylindrical body with a conical outer surface, are fitted into each of the wedge fitting portions 6 a, and when pushed inward, the wedge pieces 8 a and 8 b are tensioned. It is designed to hold the material 4.

Further, a cylindrical jack chair 9 is arranged around the outer periphery of the cone 5.

The jack chair 9 has a hollow part 9a and a tension material penetration part 9b.
A pair of T-shaped guide holes 10 and 10 are provided on the outer periphery of the jack chair 9 at substantially the center thereof and facing each other.

The tip of the jack chair 9 is in contact with the support plate 3, and a ring-shaped presser plate 11 is movably provided in the cavity 9a of the jack chair 9.

Each tendon insertion hole 6 of the cone 5 is provided in the presser plate 11.
A tendon through hole 12 is formed at a position corresponding to the tension material through hole 12, and a pair of opposing operators 13, 13 are integrally attached to the outer periphery of the presser plate 11.

The operator 13.13 is the guide hole 10 of the jack chair 9.
．． The movement of the presser plate 11 within the cavity 9a of the jack chair 9 is restricted within a predetermined range by the guide holes 10 and 10, respectively.

Then, by operating the operating element 13.13 protruding to the outside, the presser plate 11 is moved within the jack chairer, and the wedge piece 8a fitted into the cone 5 is moved.
, 8b are moved.

A known jack 14 is installed on a jack chair 9 arranged around the outer periphery of the cone 5.

An anchor head 15 is attached to a movable portion (not shown) of the jack 14.

This anchor head 15 has the same structure as the cone 5, and is anchored by a wedge 16.

In this way, the jack chair 9 has a cavity 9a, and the presser plate 11 is movably provided in the cavity 9a. The secondary tension fixing work in the tendon material tension fixing device, which is composed of the operator 13 projecting outward from the presser plate 11 and the jack 14 attached to the jack chair 9, is performed by first applying tension to each of the primarily tensioned tendon materials 4. are inserted into the tendon through holes 12 of the presser plate 11 in the jack chairer, and then the jack chair 9 is placed around the outer periphery of the cone 5 with the tip of the jack chair 9 brought into contact with the support plate 3.

Next, the tension material 4 is fixed to the anchor head 15 of the jack 14 attached to the outer end side of the jack chair 9.

When the tensioning material 4 is subjected to secondary tensioning by the jack 14 in this state, the tensioning material 4 moves in the direction of loosening the clamping force of the wedge pieces 8a and 8b of the cone 5, and accordingly Each wedge piece 8a, 8b also moves in the direction of movement of the tendon material 4 and presses against the presser plate 11, and in response to the movement of the presser plate 11, the wedge pieces 8a, 8b in each wedge insertion part 6a,
8b will each move uniformly.

After applying a predetermined prestress to each tendon material 4 in this way, when the tension on the tendon material 4 by the jack 14 is released, the tension material 4 moves in the opposite direction to the above due to its own elasticity. Each wedge piece 8 a , 8 b is also drawn into the cone 5 .

However, there are variations in the retraction of the wedge pieces 8a, 8b.

Therefore, the presser plate 11 is moved by operating the operator 13 of the presser plate 11 in the direction of pulling the wedge pieces 8a and 8b into the cone 5 in advance, and the presser plate 11 allows
Each wedge piece 8a, 8b is drawn uniformly into the cone 5, and then the tension of the tension material by the jack 14 is released, and the tension material 4 is again sandwiched between the wedge pieces 8a, 8b, and the secondary The process of fixing the tension is completed.

The tension fixing device for prestressed concrete of the present invention is constructed as described above, and includes a movable presser plate inside a jack chair, and an operator provided on the outer periphery of the presser plate and a guide hole provided on the jack chair. Since it protrudes further outward, the presser plate inside the jack chair can be moved extremely easily by operating the operator from the outside, and when performing secondary tension fixing work on the tensioning material, use the jack to secure the tensioning material. It is possible to securely and firmly bite the wedge that comes out by tensioning the tendon with the holding plate before the tension is released, and there is almost no return of the tension when the tension is released. This eliminates variations in the tension and allows the desired and accurate tension to be obtained.

[Brief explanation of drawings]

The drawings show an example of the implementation of the present invention; Fig. 1 is a partially omitted and partially cutaway sectional view showing the tension fixing device for tension material in use, and Fig. 2 shows a jack chair of the same device. FIG. 3 is a perspective view of the presser plate of the same device; FIG. 4 is a partially enlarged vertical cross-sectional view showing the state during secondary tensioning; and FIG. 5 is a perspective view showing the state after secondary tensioning. FIG. 1...Concrete structure, 4...Tension material, 5...Cone, 6...Tension material insertion hole, 6a...Wedge Inset part, 8a, sb...
... Wedge piece, 9 ... Jack chair, 10 ...
... Guide hole, 11 ... Holding plate, 12.
...Tension material through hole, 13...Operator.

Claims (1)

[Scope of utility model registration request] A plurality of tension members are inserted into a concrete structure, and a wedge piece for holding the tension members is inserted into a tapered wedge fitting portion formed at one end of the fixing cone, and the fixing cone is screwed onto the outer periphery of the fixing cone. A jack chair is provided with a cavity in which a fixing nut can be freely accommodated from one end side, and a tension material penetration part is formed in communication with the cavity to allow the tension material to be freely inserted, and the other end of the jack chair. a tensioning jack attached to the end side of the tensioning material, a movable holding plate having a tensioning material through-hole through which the tensioning material can be freely inserted into the cavity, and a holding plate protruding from the outer periphery of the holding plate. A tension fixing device for prestressed concrete tension material, characterized in that an operator extends outward through a guide hole provided in a jack chair.