JPS59165770A - Tension force adjustment of steel bar for prestressed concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the tension of a steel rod for prestressed concrete, the purpose of which is finely adjusting the tension applied to the steel rod for prestressed concrete.

A commonly used method for tensioning steel rods for prestressed concrete is to tension the steel rods using hydraulic pressure or the like. In such a method, the tension of the steel bar is determined by the amount of tension applied by the jacks, but it is difficult to finely adjust the amount of tension caused by the jacks, and it is difficult to improve the accuracy of the tension introduced into the steel bar. there were. On the other hand, depending on the quality of the steel rod, high precision is required for the introduced tension, but there is a problem in that it is not possible to meet this requirement, which becomes a major bottleneck when a product is required to have a tension as designed. .

However, in this invention, the tension plate to which the steel rods for grestressed concrete are fixed is moved with a jack to introduce a tension near the g design value, and then the screw position relationship between the inner and outer rings of the tension plate is changed. Since the tension of the steel rod is finely adjusted, it is possible to reliably introduce the designed tension with high precision, which is an improvement over the conventional method.

The present invention will be described below based on embodiments shown in the drawings.

Frame-shaped jack chair/A latching plate having a latching step 3 is fixed to the tip of the tension berth inserted into the inside, and the latching step 3 has an inner ring 5 and an outer ring B. A tension plate 7 formed by screwing together is latched.

The inner ring S is provided with a steel rod insertion hole g. 9 in the figure is an end plate of the formwork/g, which is supported by the formwork/g.

The free end of the steel rod 10 for prestressed concrete is inserted through the insertion holes g, /'/ of the end plate 9 and the inner ring S, and the NAND // is screwed into the device configured as described above. and fix it. Next, the tension bar is moved in the two directions indicated by the arrow (the tension bar 2 is connected to the fluid pressure cylinder), and the tension plate 7 is pulled in the same direction via the latching plate q to tension the steel rod 10. Then, a spacer ring/3 is interposed in the gap between the tension plate 7 and the end plate 9 created by the movement of the tension plate 7. As shown in FIG.
They are rotatably connected to each other, and are installed by fitting them into the gap in the open state (shown by chain lines in FIG. 3). The spacer ring /3 has a thickness approximately equal to the distance between the inner ring and the end plate of the tension plate 7, and a width approximately equal to the outer ring B, and is capable of supporting the tension of the steel rod 10. The material is strong enough to endure. In addition, spacer ring/
In place of 3, a plurality of appropriate blocks may be used. After inserting the spacer ring/3 as described above, the tension introduced into the steel rod 10 is measured, and if the tension is insufficient, the outer ring 6 is rotated and the inner ring S screwed therewith is rotated. Move in the direction shown/B. In contrast to the above, if the tension is excessive, the outer ring B is rotated in the opposite direction to the above, and the left inner ring is moved in the direction of arrow /7. In any of the above cases, the desired tension can be reliably and easily introduced by operating while measuring the tension.

That is, according to the present invention, after fixing the free end of the steel rod for rust concrete to the inner ring of the tension plate formed by screwing the outer ring onto the inner ring, the tension plate is moved with a jack to tighten the steel rod. After tensioning the tension plate and inserting a spacer between the outer ring of the tension plate and the end plate of the jack, the outer ring is appropriately rotated to adjust the distance between the end plate and the inner ring. Since the tension of the rod has been fine-tuned, the tension can be easily fine-tuned. Moreover, since the tension according to the design value can be reliably introduced through fine adjustment, it is possible to obtain a breast-stressed concrete product in which tension is introduced into the steel rod with high precision.

Furthermore, the present invention can be implemented as is using a conventional jacking device by simply replacing the tensioning plate.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the apparatus used for carrying out this invention;
The figure is a sectional view showing the tensioned state, and FIG. 3 is a plan view of the spacer ring.

Claims (1)

[Claims] / After fixing the free end of a steel rod for prestressed concrete to the inner ring of a tension plate formed by screwing an outer ring into a circular ring, the tension plate is moved in the axial direction with a jack to tension the steel rod, Next, after interposing a spacer between the tension plate and the end plate of the formwork, the outer ring is appropriately rotated in a desired direction to adjust the distance between the end plate and the inner ring, so that the steel rod is [Prestress characterized by finely adjusting the tension to be introduced]-Method for adjusting the tension of a steel rod for concrete λ The distance adjustment is performed while measuring the tension. How to adjust the tension of steel rods for prestressed concrete