JP2000155059A - Tension measuring method for tension cable and lateral load measuring jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical tension measuring method for a tension cable capable of measuring the tension of the cable under tension at any suspended position regardless of length and abundant in simplicity, reliability and flexibility and to provide a lateral load measuring jig directly used for the implementation of this method. SOLUTION: In this tension measuring method, two positions at the prescribed interval of a cable 6 under tension are fastened and fixed, the cable 6 is pulled in the direction perpendicular to the cable core by a hook section 9 hooked on the prescribed intermediate position, the cable tension length is adjusted, the reaction applied to the hook section 9 is measured by a load measuring means 5, and the regression straight line L to the reaction of the cable tension is determined for various test cables with a lateral load measuring jig capable of measuring the lateral load to the cable 6 in advance. The measured value is obtained by the lateral load measuring jig for the cable 6 suspended actually, the measured value is collated with the value corresponding to the regression straight line L, and the tension at that time is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension which allows a simple and easy measurement of the tension of a cable used as a structural member used in a structure such as civil engineering or construction. The present invention relates to a method for measuring the tension of a cable and a jig for measuring a lateral load which is directly and suitably used in carrying out the method. The cables to be subjected to the tension measurement include reinforcing cables and monument cables used for suspension materials of bridges, building roofs, and glass walls.

[0002]

2. Description of the Related Art The above-mentioned reinforcing cable and monument cable exhibit their effectiveness only when a predetermined tension is applied. However, it is known that the management of the tension is very important because the phenomenon of excessive application of tension or loosening leads to a serious accident such as collapse of a structure.

Conventional cable tension measuring methods are roughly classified into a load cell measuring method, a strain gauge measuring method,
There are five types: a jack load measuring method, a vibration measuring method, and a bending measuring method. Load cells are of a tension type and a compression type. Both are built into terminal fittings used at the end of the cable, and are measuring instruments that measure the amount of distortion and convert it into tension. Although it has a high advantage, it is expensive and cannot be removed unless the tension is released when it is assembled into a cable, so that it is generally in a so-called buried state and the cost is high.

[0004] A strain gauge is a member that is attached to a cable terminal fitting and measures the amount of strain to determine the tension. Performance degradation cannot be denied as compared with a load cell, but measurement accuracy is good. Have been. However,
The problem is that they are easily damaged, have poor durability, and have a short life.

[0005] When measuring the jack load, when the cable end is pulled in using a jack and tightened, the jack is set in the same manner as at that time, and the oil pressure at the moment when the joint portion of the fixing portion becomes free is measured. This method measures the load and converts it into tension. However, it takes a lot of time and effort to set the jack, and in many cases, it cannot be set after the tension, and there is a problem that the use is restricted.

[0006] The vibration method is a method of measuring the natural frequency by vibrating a cable having an accelerometer attached to its surface and obtaining the tension based on the string theory. The fixed part resonates or vibrates. The measurement cannot be performed if there is an obstacle that comes into contact with the cable and disturbs the waveform, the application range is narrow, and the measurement accuracy is deteriorated as the cable is thicker and shorter. The bending measurement method is a method of measuring the amount of bending between fixing points (fixed portions) of a cable to determine the tension. When the tension is short and the tension is large, the bending is small and unsuitable. Even in the case of a long span, there is a problem that it is difficult to measure.

[0007]

As described above, in the conventional tension measuring method, is limited to the measurement of the tension at the cable end, there is an inconvenience that the use range is narrow, and In some cases, there is a problem that reliability becomes low and measurement becomes impossible. In recent years, taking advantage of the characteristics of cables that can be freely bent, such as cable girder (girder) for glass walls, string beams on roofs, cable nets, etc., a long single real cable is bent and penetrated through a fixed part. In addition, there is an increasing number of structures that are used continuously while minimizing connection parts. In this case, since the span (span) between the intermediate bending points is constituted only by the wire rope (cable), the measuring method of (1) cannot be applied, and the fixed portion of this portion may be unstable. At most, it will be impossible to adopt.

The present invention has been made to solve such a problem, and the present inventors have a characteristic that the repulsion force varies depending on the magnitude of the tension applied to the cable. Focusing on, we have developed a unique configuration of lateral load measuring jig that can be easily attached to a cable with a compact shape, and furthermore, a new measuring method that can easily measure tension using this measuring jig Thus, the present invention provides a cable under tension where tension is applied, where
Measurements can be made anywhere, regardless of their length.
It is an object of the present invention to provide a practical tension measuring method for a tension cable, which is simple, reliable and versatile, and to provide a lateral load measuring jig directly used for implementing the method.

[0009]

The present invention has the following configuration to achieve the above object. That is, in the invention of claim 1 according to the present invention, two portions of the tensioned cable 6 at predetermined intervals are tightened and fixed, and a predetermined intermediate portion thereof is perpendicular to the cable core by a hook portion 9 hooked at the location. A lateral load measuring jig capable of measuring the lateral load on the cable 6 by adjusting the cable pulling length at that time and measuring the reaction force acting on the hook portion 9 by the load measuring means 5. 1 to measure the reaction force corresponding to the tension variation of the cable 6 under the condition that the cable tension length is constant with respect to the initial reaction force of a predetermined value acting on the hook portion 9 for various kinds of test cables. A regression line of the cable tension to the reaction force calculated based on the relationship between the cable tension and the reaction force based on the measurement result is determined in advance, and the regression line is set at an appropriate position with respect to the cable 6 actually stretched. The weight measuring jig 1 is set in the same manner as described above, the cable pulling length from the initial reaction force is set to the same value as above, and the measured value of the load measuring means 5 at that time is obtained. A tension measuring method for a tension cable, wherein the tension of the cable 6 is determined by comparing the tension with a corresponding one of the regression lines.

A second aspect of the present invention relates to a lateral load measuring jig 1 used directly when the method for measuring the tension of a tensioned cable according to the first aspect is applied. It has a base 2 to be formed and a clamp 7 on the tip side,
The rear end side is attached to each of both ends of the base 2, and is provided in a symmetrical relationship in which the rear end side is orthogonally shifted to the base 2. 7 has a pair of clamp members 3 for fastening and fixing, and a hook portion 9 on the front end side, and has a rear end side on the base portion 2.
The hook 9 is movably attached to and separated from the base 2 in a direction orthogonal to the base 2. A predetermined intermediate portion including the center of the cable 6 between the clamp members 3 is provided at the center. A cable tension member 4 for tensioning the cable core in a direction perpendicular to the cable core and adjusting the cable tension length at that time, and an interposition between the base 2 and the rear end side of the cable tension member 4. And a load measuring means 5 for measuring a reaction force acting on the hook portion 9 generated by pulling the cable 6 as a lateral load on the cable 6.

According to a third aspect of the present invention, there is provided the lateral load measuring jig 1 according to the second aspect, wherein the cable pulling member 4 has a nut 12 screwed on one end side and a base 2
And a hook portion 9 fixed to the other end of the screw shaft 11. The load measuring means 5 is formed in a cylindrical body and has a hollow center. A screw hole 11 is loosely inserted into the portion and a center hole type load cell is provided between the central portion of the base 2 and the nut 12. The cable in the hook portion 9 is defined by defining the number of rotations of the nut 12. The present invention is characterized in that the tensile length can be set to a certain condition.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a front view of a lateral load measuring jig 1 according to an embodiment of the present invention, and FIG.
Is a side view taken along the line AA in FIG. 2, and FIG.
, Respectively, are respectively shown in side view along the line BB.

Referring to FIGS. 1 and 2, the lateral load measuring jig 1, which is a jig used directly when implementing the tension measuring method of a tension cable according to the present invention, includes a base 2 and a pair of clamps. Member 3, cable tension member 4, load measuring means 5
Are constructed as constituent members, and can be attached to the tensioned cable 6 to measure the lateral load applied to the cable 6.

The base 2 is a base member to which the pair of clamp members 3, the cable tension member 4 and the load measuring means 5 are attached. For example, a 2 × 4 × 40 × 5 mm straight angle steel having a length of several hundred mm is used. , 2B are arranged in parallel with an appropriate distance therebetween, and both ends are connected and fixed by a connecting member (not shown) to form a base having a flat mounting surface. Is done.

The clamp members 3 are formed into the same shape and the same size, and are assembled to the base 2 as a pair. The clamp member 3 has a clamp portion 7 on the front end side and a mounting portion 8 made of a flat steel plate on the rear end side. The mounting portions 8 are mounted on both ends of the base 2 respectively, and are directly connected to the base 2. It is fixed to the crossed symmetry. The mounting portion 8 is formed of, for example, a flat steel plate, and a tubular body 15 realized by a nut is fixed upright to a central portion on the upper surface side, while a hook guide 17 formed of a rectangular tubular body is formed of the flat steel plate. The cylindrical body 15 and the hook guide 17
Have a coaxial relationship with each other, and are provided at right angles to the mounting portion 8 made of a flat steel plate.

A clamp shaft 16 is screwed to the cylindrical body 15, and the clamp shaft 16 is formed in a screw rod and extends approximately half length into a hook guide 17, while Inside the hook guide 17, a clamp portion 7 including a lower clamp piece 13 and an upper clamp piece 14 is provided.
And the lower clamp piece 13 is attached to the hook guide 1.
7, the upper clamp piece 14
Is slidably housed inside the cylinder at a position above the lower clamp piece 13. The upper clamp piece 14 is fixed by welding a channel-shaped connection fitting 27 having a hole through which the clamp shaft 16 penetrates on the upper surface, and the distal end portion of the clamp shaft 16 is inserted through it. In this state, between the upper surface of the upper clamp piece 14 and the upper surface of the connection fitting 27, the clamp shaft 16 and the clamp portion 7 are connected by attaching a stopper to the distal end of the clamp shaft 16 inserted therethrough.
The clamp shaft 16 has a handle 21 for clamping the clamp at the upper end.

The clamp member 3 having such a structure includes:
The hook guide 17 is fitted from above into the gap between the two right angle steels 2A, 2B forming the base 2, and the mounting portion 8 is fixed to the upper surfaces of the right angle steels 2A, 2B by bolting or welding. Thereby, it is fixed to both ends of the base 2 in an orthogonally different shape. The hook guide 17 includes the base 2.
A cut 20 extending across a side surface parallel to the longitudinal side surface and extending to a substantially central portion of both connecting side surfaces is cut, and the cable 6 is housed in the cylinder using the cut 20. The lower clamp piece 13 and the upper clamp piece 14 can be inserted into cable receiving grooves.

When the handle 21 is rotated in the counterclockwise direction, the upper clamp piece 14 screwed with the clamp shaft 16 rises with the rotation of the clamp shaft 16 in the same direction. As a result, the clamp 7 is moved to the open side. Conversely, when the handle 21 is rotated in the clockwise direction, the upper clamp piece 14 descends and comes closer to the lower clamp piece 13 with the rotation of the clamp shaft 16 in the same direction, and the clamp portion 7 operates to the tightening side. I do.
Therefore, the notch 20 is operated by operating the handle 21.
The cable 6 inserted from above can be tightened by the clamp portion 7 or opened to be loosened.

The cable pulling member 4 includes a hook portion 9, an attaching portion 10, a screw shaft 11, a nut 12 screwed to the screw shaft 11, and a co-rotation preventing loosely fitted to the screw shaft 11. It is composed of a washer 19, and is provided so as to be movable so that the mounting portion 10 is mounted on the central portion of the base portion 2 and the hook portion 9 is brought into contact with and separated from the base portion 2 in a direction orthogonal to the base portion 2. The hook portion 9 has a hook piece hooked on the cable 6 and is fixed to a lower end portion of the screw shaft 11. The mounting portion 10 includes, for example, two side plates 2.
It is formed in a channel steel-shaped frame consisting of two top plates 23 and one top plate 23, and is bridged to the upper surfaces of two right angle steels 2 </ b> A and 2 </ b> B forming the base 2 and fixed by welding or the like. The screw shaft 11 is inserted through a hole provided in the top plate 23, and vertically passes through a gap between the two right angle steels 2A and 2B. It is fixed by means such as screwing or welding.

A load cell guide 18 is fixed to the upper surface of the top plate 23 in the mounting portion 10, and the load measuring means 5 realized by a load cell is mounted on the load cell guide 18.
Is mounted and fixed. The load cell 5 is a load measuring device of a cylindrical shape having a hollow portion at the center, which is called a center hole type. By assembling the load measuring device and the cable tension member 4 as described below, a lateral load is measured. A lateral load measurement part in the measurement jig 1 is configured.

That is, with the load cell 5 installed and fixed on the load cell guide 18, the hook 9 is attached to the other end.
The screw shaft 11 to which is fixed is connected to two straight angle steels 2.
A and 2B are passed through from below, through the hole provided in the top plate 23 and the hollow portion of the load cell 5, the washer 19 is loosely fitted into the screw portion at the upper end, and the nut 12 is inserted. The load cell 5 and the cable pulling member 4 are screwed together and the base 2
It is assembled at the center of.

The cable pulling member 4 assembled as described above takes a form in which a screw shaft 11 having a hook 9 at a distal end thereof hangs from a central portion of the base 2 via a mounting portion 10 and a load cell 5. By turning the nut 12 in this state, the hook 9 can be moved in a direction orthogonal to the line connecting the base 2 and the hook 6 of the pair of clamp members 3 (the axis of the clamped cable 6). ,
When the nut 12 is turned clockwise, the screw shaft 11 rises and the hook 9 approaches the base 2. Conversely, when the nut 12 is turned counterclockwise, the screw shaft 11 goes down and the hook 9 moves away from the base 2. I will leave.

Next, a method for measuring the tension of a tension cable according to the present invention, which is performed using the lateral load measuring jig 1 having the above-described configuration, will be described. FIG. 3 (a) is a plan view of an experimental body used for measurement by the lateral load measuring jig 1, FIG. 3 (b) is an elevation view thereof, and FIG. A side view is also shown.

Before the present invention measures the tension of the cable 6 actually stretched by the lateral load measuring jig 1,
The lateral load was measured using the experimental body shown in FIG. 3 simulating the same conditions as the actual conditions, and the regression line to the reaction force of the cable tension calculated based on the relationship between the cable tension and the reaction force based on the measurement results was calculated. It is determined in advance.

The experimental body shown in FIG. 3 is a reinforced cable girder used to structurally reinforce the glass front wall in an actual building in which the outer peripheral wall is formed by a glass facade. ), A series of reinforcing cables 6 extending over a span s of, for example, 5550 mm between two support members 25 supporting the front glass wall 24 with reference to FIG. Are stretched as a set of two, and two bundles 26 are equally arranged in one span, and a pair of reinforcing cables 6 are crossed between the support 25 and the bundle 26. An example is shown in which the hanging members 26 are stretched in parallel between the bundle members 26.
In the case where the tension cable 6 becomes a terminal portion at the point a in FIG. 5, the tension can be directly measured by using the load cell 5 here. However, at the point a where the tension cable 6 is further continuous, and b and c. It is not possible to directly measure the tension of the reinforcing cable 6 at each location.

In such a case, the present invention provides a lateral load measuring jig 1 for b or c in the tension cable 6.
Is set, and a predetermined interval (for example, 300 mm) of the cable 6 is set by the clamp portions 7 of the pair of clamp members 3.
The lateral load measuring jig 1 is fixed to the cable 6 by tightening the portion, and then the hook 9 of the cable pulling member 4 is hooked on the cable 6, and the screw shaft 11 is rotated to a predetermined initial reaction force (eg, about 50 kgf). The nut 12 is tightened.

From this state, the nut 12 is turned a predetermined number of times (for example, about two times), and the reaction force at that time is read from the load cell 5. In this case, the tension is variously changed for each type of the test cable 6, and the relationship between the tension and the reaction force is investigated in advance (calibration), and the tension is determined accordingly. By fixing with the clamp member 3 in this manner, since the elongation caused by the pull-in by the hook portion 9 occurs only between the clamp portions 7, the same result can be obtained regardless of the length of the measurement cable for the same cable. It goes without saying that it can be obtained.

FIG. 4 shows an example of a relationship diagram between the cable tension and the load cell value based on the measurement result by the lateral load measuring jig 1. In the case where the number of samples is 7 and the nut 12 is rotated twice. Measurement result (calibration value: ○ in the figure)
Are shown in [Table 1], and from this result, a regression line L of the cable tension x to the reaction force y determined by the least square method is y = 0.14 + 0.0954x.
And the adopted values based on the regression line L are shown in [Table 2].

[0030]

[Table 1]

[0031]

[Table 2]

After the regression line L is determined in advance in this way, the main measurement is subsequently performed. That is, the lateral load measuring jig 1 is set at an appropriate position on the cable 6 actually stretched in the same manner as described above, and the nut of the screw shaft 11 is adjusted to the initial reaction force (eg, about 50 kgf). 1
2, the nut 12 is turned a predetermined number of times (for example, about two times), and the reaction force at that time is read from the load cell 5. The measured reaction force is collated with the regression line L to determine the tension at that time. In addition, in the case of the above [Table 1] and [Table 2], the difference between the actual tension and the calculated tension obtained from the regression line L is within ± 2%, which indicates that the reliability is extremely high. It is specified.

[0033]

The present invention is embodied in the form described above and has the following effects. That is, according to the present invention, it is possible to measure the tension (based on the lateral load measurement) without any problem not only at the end portion of the tensioned cable but also at the intermediate cable extending portion, and the bending point which has been considered impossible in the past. There is an advantage that it can be applied to a portion consisting only of a tension cable, such as a span, so that tension management at a construction site can be performed easily and rationally. Further, the present invention can be carried out only by using a lateral load measuring jig having a compact structure. Since the measurement can be performed by simple work in addition to the simple attaching / detaching operation, the present invention can be diverted to another measuring point or used as a sample. You can change it without any problem.

[Brief description of the drawings]

FIG. 1 is a front view of a lateral load measuring jig according to an embodiment of the present invention.

2A is a side view taken along the line AA in FIG. 1, and FIG. 2B is a side view taken along the line BB in FIG.

3A is a plan view of an experimental body used for measurement by the lateral load measuring jig shown in FIG. 1, FIG. 3B is an elevation view thereof,
(C) is a side view of the same.

FIG. 4 is a relationship diagram between a cable tension and a load cell value based on a measurement result by the lateral load measuring jig shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Side load measuring jig 2 ... Base 3 ... Clamp member 4 ... Cable tension member 5 ... Load measuring means 6 ... Cable 7 ... Clamp part 8 ... Attachment part 9 ... Hook part 10 ... Attachment part 11 ... Screw shaft 12 ...
Nut 13 ... Lower clamp piece 14 ... Upper clamp piece 15 ...
Nut 16 ... Clamp shaft 17 ... Hook guide 18 ...
Load cell guide 19 ... Washer 20 ... Cut 21 ...
Handle 22 ... Side plate 23 ... Top plate 24 ...
Glass front wall 25 ... Support material 26 ... Bundle material 27 ...
Connection bracket

Claims (3)

[Claims] 1. A tensioned cable is fastened and fixed at two predetermined intervals, and a predetermined intermediate portion is pulled in a direction perpendicular to a cable core by a hook portion hooked at the predetermined portion, and the cable tension at that time is pulled. By adjusting the length and measuring the reaction force acting on the hook with a load measuring means, a lateral load measuring jig capable of measuring the lateral load on the cable is used. Measure the reaction force corresponding to the cable tension variation under the condition that the cable tension length is constant based on a predetermined value of the initial reaction force acting on the cable, and based on the relationship between the cable tension and the reaction force based on the measurement result, The regression line of the calculated cable tension to the reaction force is determined in advance, and the lateral load measuring jig is attached to an appropriate portion of the actually stretched cable in the same manner as described above. Setting the cable tension length from the initial reaction force to the same value as above and obtaining the measurement value of the load measuring means at that time, and comparing this measurement value with the corresponding one of the regression line. Wherein the tension of the cable is determined by the following method. 2. A symmetrical relationship in which a base formed in a straight body and a clamp portion are provided at a front end side, and rear end sides are attached to both end portions of the base portion, respectively, and are orthogonally connected to the base portion. A pair of clamp members for tightening and fixing two places at a predetermined interval of the cable tensioned in parallel to the base with the clamp part, and a hook part on the tip side,
A rear end side is attached to a central portion of the base, and the hook portion is provided so as to be movable so as to contact and separate the hook portion in a direction orthogonal to the base portion. A cable pulling member for pulling in a direction perpendicular to the cable core by the hook portion hooked at the point and adjusting a cable pulling length at that time, and between the base and the rear end side of the cable pulling member. And a load measuring means for measuring a reaction force acting on the hook portion caused by pulling the cable as a lateral load on the cable. 3. A cable pulling member comprising: a screw shaft having a nut screwed to one end thereof and inserted in a direction perpendicular to the center of the base; and a hook fixed to the other end of the screw shaft. The load measuring means comprises a center hole type load cell formed in a cylindrical body, the screw shaft being loosely inserted into a central hollow portion, and being interposed between the central portion of the base portion and the nut. The lateral load measuring jig according to claim 2, wherein the cable pulling length at the hook portion can be set to a predetermined condition by defining the rotation speed of the nut.