JPH026012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the tension of a prestressing cable head of a prestressed structure, such as a nuclear reactor pressure vessel, by means of a resistance strain gauge.

The purpose of the invention is to reduce the entire device or a part of the device in the tensioned state of the pre-stressing cable, in order to obtain good measurement accuracy without disturbing the pre-stressing cable and to improve the monitoring of structures. To provide a tension measuring device which can be attached/detached and repaired.

The device according to the invention consists of a hollow cylinder joined to at least two segmented tubular bodies, each segmented tubular body being equipped with its own resistance strain gage, the applied force being separately measured and A cylinder is arranged between the anchor plate supported by the prestressing structure and the prestressing cable head, which achieves the above object.

When an individual resistive strain gauge stops working, it must be possible to remove or repair the device to prevent a loss of measurement accuracy. If the tension measuring device can only be attached and detached when the prestressing cable is loosened, it must be taken into account that the corrosion protection of the prestressing cable will be damaged. In any case, in order to guarantee reliable cable protection, it may even be necessary to remove the entire cable and renew or replace the corrosion protection. This results in tedious repositioning operations and long downtimes of parts arranged in the structure. Therefore, the device of the present invention has an important significance in that it can be assembled and disassembled while keeping the prestressing cable under tension due to its special configuration.

According to the present invention, not only can a malfunctioning hollow cylinder be replaced, but also an auxiliary hollow cylinder can be attached to a malfunctioning hollow cylinder. It is also possible to subsequently equip the tensioned prestressing cable with the device of the invention. Also, remove the device,
Calibration of the device is also possible since it is easy to reinstall. Another advantage is that tilting and machining errors can be easily compensated for. Moreover, the time and expense associated with repairing or replacing malfunctioning equipment is reduced. The updated or repaired device is simply inserted between the anchor plate and the taut cable head.

The wall thickness and material of the split cylindrical body are selected so that the maximum stress is always below the proportional limit or yield point of the material used. That is, either the cross-sectional area of the hollow cylinder is selected to be larger than the cross-sectional area of the prestressing cable head, or a higher strength material is used for the hollow cylinder.

Each segmented tube is equipped with such a number of resistive strain gauges that a reasonable average value of the measured values is obtained and that the applied forces are measured accurately to a few percent. The summation of the forces measured on the individual segmented cylinders is first carried out in the form of processing of the measured values and not directly on the hollow cylinders.

Preferably, the connection terminals of the resistance strain gauge are led out of the hollow cylinder and connected to the measuring bridge only outside the hollow cylinder. When an individual resistance strain gauge is not working, it can be disconnected from the corresponding measuring bridge. Also, in that case, it is easier to access the measuring bridge for repairs. In this way, the measurement bridge is prevented from being damaged by a malfunctioning resistive strain gauge, and still healthy resistive strain gauges can be rewired to each other.

When installing a resistance strain gauge on a divided cylindrical body,
There are various ways to do it. For example, resistance strain gauges can be attached to the inner and outer peripheral surfaces of each divided cylindrical body. In the case of a minimal installation, two resistance strain gauges are placed on the inside and another two on the outside. In the hole that extends radially through the wall of the divided cylindrical body,
It is highly preferred to store resistive strain gauges. In this way of arrangement, all resistive strain gauges are more accessible for repair and are better protected than in the first case.

Preferably, each split tube is equipped with an extra resistive strain gauge. When an individual resistance strain gage is damaged, it is possible to switch to another resistance strain gage, so that measurement accuracy is not unduly impaired.

In order to sufficiently shield the resistance strain gauge against the influence of disturbances associated with the introduction of force, at a sufficient distance from the force introduction surface, i.e. in an area where the influence of said disturbances disappears; It is appropriate to provide a resistive strain gauge.

Preferably, a split distance ring is inserted between the hollow cylinder and the fixing plate and between the hollow cylinder and the prestressing cable head. This distance ring, together with the hollow cylinder, creates the distance between the fixing plate and the prestressing cable head that is necessary to obtain the prestressing of the prestressing cable. After the split distance ring is a hollow cylinder and the prestressing cable is stretched, it is inserted into the gap between the fixing plate and the head of the prestressing cable. The distance ring ensures approximately uniform loading of the segmented tube.

If necessary, in order to better balance the uneven support of the split tube, the thickness of one or more split distance ring segments may be graded by suitable machining. can be provided. In this way, tilting between the fixing plate and the prestressing cable head is avoided.

Another way to compensate for such tilt is to
Made of plastically deformable material. The method is to use a thin compensator plate in the form of a split ring. This compensation plate is inserted between the hollow cylinder and the fixing plate or between the hollow cylinder and the head of the prestressing cable, either alone or together with the above-mentioned distance ring. Stresses above the yield point appear only in localized areas with stresses above the average tension. Excess or maximum loads resulting from non-uniform loading are eliminated by plastic deformation, so that the loads are equalized. For the compensator plate, a small thickness is selected so that only a small tension loss occurs in the thickness direction during the plastic deformation process.
For example, when the tension is about 20 cm, choose a board thickness of 1 to 2 mm. Assuming complete plastic deformation, this is 1~
This corresponds to a loss of tension of only 2%. This value is still within the measurement accuracy.

As another modified configuration for compensating the processing and assembly accuracy of the fixing plate and the prestressing cable head, we propose the use of a split ring with one end surface formed into a spherical shape. Two split rings are each arranged with their spherical surfaces touching each other between the hollow cylinder and the fixing plate or between the hollow cylinder and the head of the prestressing cable. On the one hand, by the frictional forces and, on the other hand, by the selection of the sphere radius, which determines the magnitude of the horizontal force at a given prestressing cable head dimension.
Escape of the split ring is prevented.

Hereinafter, embodiments of the apparatus of the present invention shown in the drawings will be described.

In the embodiments shown in FIGS. 1 to 3, different modified configurations are disclosed for the right and left portions, respectively.

FIG. 1 shows a part of a prestressed concrete pressure vessel 1 as a prestressed structure and a pipe 2 laid in concrete. A prestressing cable consisting of a large number of prestressing steel wires 3 is routed inside the tube 2 . The prestressed cable is provided with corrosion protection and is cooled by the liquid flowing through the tube 2. An anchoring plate 4 is placed above the concrete pressure vessel 1 in the tube opening area.

The prestressing steel wire 3 is fixed using a perforated plate 6.
This is done by means of a prestressing cable head 5 consisting of a support nut 7 and a support nut 7. The end of the prestressing steel wire 3 is passed through a perforated plate 6 and fixed to the end surface of the perforated plate by a fixing part 8.

The tension measuring device consists of two halved cylindrical bodies 10.
A hollow cylinder 9 joined with a plurality of resistance strain gauges 1
Consists of 1. The connection terminals of the resistive strain gauge 11, which are individually measured with respect to the applied force, lead out of the hollow cylinder 9, where a measuring bridge (not shown)
connected to.

In the modified configuration shown on the right side of FIG.
Four resistance strain gauges 11 are provided for each tube, two of which are disposed on the inner circumferential surface of the cylindrical body 10 and two on the outer circumferential surface. In the other variant on the left side of FIG. 1, the cylindrical wall of the half-cylindrical body 10 is provided with a radial hole 12 in which a resistance strain gauge 11 is housed. In addition, in the example, the number of strain gauges is six. Further, an extra cylindrical body 10 can be provided. In all resistance strain gauges 11 of the two deformation configurations, the distance from the force introduction surface is selected to be such that the influence of disturbances is no longer perceptible.

A plurality of split distance rings 13 are inserted between the hollow cylinder 9 and the fixing plate 4 and between the hollow cylinder 9 and the prestressing cable head 5, and cooperate with the hollow cylinder 9 to connect the fixing plate 4. Maintain the correct spacing between the prestressing cable head 5.
This distance ring 13 is provided to avoid uneven loads on the individual cylindrical bodies 10 due to manufacturing precision and assembly precision.

If a larger compensation is required, the thickness of each divided piece of the distance ring 13 can be made to have a stepwise difference by cutting (not shown).

As is clear from FIG. 1, the cross section of the hollow cylinder 9 is selected to be larger than the support nut 7 and the distance ring 13, so that for a given material, the maximum stress in the hollow cylinder 9 is always higher than the yield point of the material. low.

In the embodiment of FIGS. 2 and 3, parts corresponding to those of the embodiment of FIG. 1 are given the same reference numerals.

In FIG. 2, in addition to the split distance ring 13 between the fixing plate 4 and the hollow cylinder 9 and between the prestressing cable head 5 and the hollow cylinder 9, a split compensation plate 14 is provided. . The compensator has a very small thickness and is made of plastic material. In this case, the non-uniformity of the load on the halved cylindrical body 10 is compensated for by plastic deformation of the compensating plate 14.

In the embodiment shown in FIG. 3, a split ring 15 is used instead of a distance ring or compensator plate to compensate for manufacturing and assembly accuracy. Each of the split rings 15 has a spherical end face 16. Two of these split rings 15 are each inserted between the fixing plate 4 and the hollow cylinder 9 on the one hand and between the prestressing cable head 5 and the hollow cylinder 9 on the other hand, with each pair of split rings being inserted. The spherical end surfaces touch each other. Due to friction and the special selection of the sphere radius, escape of the split ring 15 is prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a first embodiment of the device according to the invention with a split distance ring; FIG. 2 is a second embodiment of the device according to the invention similar to FIG. FIG. 3 is a schematic cross-sectional view of a third embodiment of the device of the invention having a split ring with a spherical end surface. 1...Prestressed concrete pressure vessel, 4
...fixing plate, 5...prestressing cable head,
9...Hollow cylinder, 10...Divided cylindrical body of hollow cylinder, 1
1...Resistance strain meter.

Claims (1)

[Claims] 1. A tension measuring device for the head of a prestressed cable of a prestressed structure using a resistance strain meter, which comprises a hollow cylinder 9 in which at least two divided cylindrical bodies 10 are joined together; 10 are each equipped with its own resistance strain gauge 11 and the applied force is measured separately, and the hollow cylinder 9
is disposed between a fixing plate 4 supported by a prestressing structure 1 and a prestressing cable head 5. 2. The device according to claim 1, wherein the connecting terminal of the resistance strain gauge 11 is led out of the hollow cylinder 9 and connected to the measuring bridge only outside the hollow cylinder 9. 3. Claim 1, in which the resistance strain gauges 11 are disposed on the inner peripheral surface and the outer peripheral surface of each divided cylindrical body 10.
The device according to paragraph 2 or paragraph 2. 4. Claim 1, in which a resistance strain gauge is disposed inside the radial hole 12 of the divided cylindrical body 10.
The device according to paragraph 2 or paragraph 2. 5 Each of the divided cylindrical bodies 10 is a resistance strain meter 1
1. The device according to claim 1, further comprising: 1. 6. The device according to claim 3 or 4, wherein the resistance strain gauge 11 is arranged at a sufficient distance from the force introduction surface. 7. The device according to claim 1, wherein a split distance ring 13 is inserted between the hollow cylinder 9 and the fixing plate 4 and between the hollow cylinder 9 and the prestressing cable head 5. 8. A patent claim in which a step is provided in the thickness of one or more divided pieces of the distance ring 13 by cutting so that the divided cylindrical body 10 of the hollow cylinder 9 is uniformly loaded. The device according to item 7. 9 Between the hollow cylinder 9 and the fixing plate 4, or between the hollow cylinder 9 and the prestressing cable head 5,
8. The device as claimed in claim 1, further comprising a thin compensating plate (14) in the form of a split ring made of plastically deformable material. 10 Two split rings 15 are arranged between the hollow cylinder 9 and the fixing plate 4 or between the hollow cylinder 9 and the pre-stressing cable head 5, and the opposing end surfaces thereof are formed into a spherical shape. An apparatus according to claim 1, comprising: