JPH08302618A - Method and device for slip prevention for strand in tower saddle part - Google Patents

Abstract

PURPOSE: To eliminate a large-sized strand holding device and make reasonable the operations of and suppress the costs of laying overhead the cables for construction of a bridge by responding instantly to variation of the strand tension originating from daily temp. change throughout the day, and hindering positively the generation of a strand slip in the side tower saddle part. CONSTITUTION: A saddle 3A installed at the top of the side tower 3 of a suspension bridge is made in a movable structure in the longitudinal direction of a cable strand 12 to be stretched overhead. The saddle position where no strand slip is generated is determined by balaning the stresses in the left and the right cable strand 12 while the position of the saddle 3A and the tensions of the cable strands 12 extending to the left and right main towers and to the anchorage side are put under monitoring. The saddle 3A is forcedly moved to the saddle position at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a suspension bridge having a side tower, prevents slippage between a saddle and a strand in a side tower part in the course of erection in consideration of a cable strand (hereinafter abbreviated as strand) erection stage. However, the present invention relates to a method for preventing slippage of a strand in a suspension bridge side tower saddle part capable of laying a strand, and an anti-slip device suitable for use in carrying out the method.

[0002]

2. Description of the Related Art In a side tower type suspension bridge, generally, tensions on both sides of the side tower are likely to be unbalanced, and in addition, since the bending angle of the strand is quite small, during the construction of the strand and after completion, The cable on the side tower saddle is slippery. Regarding this cable slip, there are problems of the side tower structure and the strand arrangement determined from the design concept of the entire suspension bridge system, and the specific erection method of how to lay those strands in response to this. To do.

Regarding the side tower structure and the arrangement of strands, (a) a structure in which the side tower is a rocker type and extra strands are added between the backstays in order to alleviate the stress imbalance of the cables on the left and right of the side tower ( (Eg, Onaruto Bridge),
(b) A structure in which the side tower is a flexible type, and without adding extra strands, the saddle retaining lid is used to counteract the cable stress imbalance between the left and right side towers (eg, Shiratori Ohashi)
There are two examples. In any case, it is necessary to delve into the strand erection stage of each strand as a study during strand erection.

As a typical prior art relating to prevention of strand slippage during strand construction, Japanese Patent Publication No. 56-44967.
Japanese Patent Publication, Japanese Patent Publication No. 4-20441, Japanese Patent Publication No. 4-260
The one disclosed in Japanese Patent Publication No. 02 is cited. Among those prior arts, extra strands are added in the backstay span to reduce the cable stress in the span. In this case, as a method of mitigating the strand stress unbalance force on the left and right side towers, is to try to deal with it while controlling the tension of the extra strand by attaching a counterweight to the saddle,
Then, the catwalk system is used to control the tension while controlling the tension of the extra strand. On the other hand, with regard to (1), it relates to a strand pressing device for assisting the method of (1), which is a device used for increasing the frictional force between the strand and the saddle.

[0005]

In any of the methods of the above-mentioned prior arts, the frictional force between the strand and the saddle exerts its effect within a certain temperature change range due to the difference of seasons, Slip can be prevented, but 1 round
Even though the temperature changes considerably during the day and the temperature difference is large especially at night and day, it is technically difficult to use it as a countermeasure against this temperature change.
It is indispensable to use the strand pressing device as disclosed in the above.

Considering the mechanism of strand slip, (1) Even if the strand tension between the side span and the backstay span is adjusted at a certain temperature and the strand tensions on the left and right sides of the side tower are matched, Due to the temperature change of the strand itself, there will be a difference between both tensions based on the change in the tension situation due to the expansion and contraction of the strand. (2) On the other hand, the catwalk system connected to the side tower also changes due to the temperature change. This will cause tension imbalance between the left and right sides, which will displace the side tower itself. (3) As a result of the synergistic effect of the above two points, the strand tension unbalance between the left and right side towers will increase, and the strand and saddle Strands will slide on the side tower saddle when the allowable friction force between them is exceeded, even if it is in the saddle position and the side tower position is set correctly at some point. It just addresses the temperature change over several days, it is almost impossible to avoid to cause a strand slippage.

As described above, a strand pressing device having a large-scale structure is required for the cross-linking work.
In addition, it takes a lot of man-hours and time to handle it, which is a problem in the cross-linking work.

The present invention has been made in order to solve such problems, and an object of the present invention is not only due to seasonal temperature fluctuations but also due to daily temperature fluctuations throughout the day. It is possible to immediately respond to fluctuations in the strand tension that occurs and to prevent strand slips from occurring in the side tower saddle, so that a large strand pressing device can be omitted and bridge cable erection work can be omitted. It is to achieve rationalization and cost reduction.

[0009]

The present invention has the following configuration to achieve the above object. That is, the present invention is a movable structure capable of moving in the longitudinal direction of the cable strand stretched over the saddle provided at the top of the suspension bridge side tower, and the position of this saddle and the main tower side on both left and right sides from the side tower. While monitoring each tension of the cable strands extending to the anchorage side, the saddle position that does not cause strand slip due to the balance of the stress of the left and right cable strands is obtained, and the saddle is always forcibly moved to the saddle position. This is a method for preventing strand slippage in the suspension bridge side tower saddle part.

According to the present invention, the saddle is provided at the top of the suspension bridge side tower so as to be horizontally movable in the longitudinal direction of the cable strand to be stretched, and is connected to the saddle to forcibly move the saddle in the longitudinal direction of the cable strand. Transportation means,
Saddle position detecting means for detecting the saddle position as a displacement from the reference point, tension calculating means for calculating each tension of the cable strands extending from the side tower to the main tower side and the anchorage side on the left and right sides, and the tension calculating means Saddle position calculation means for calculating the saddle position where the stress of the left and right cable strands does not cause balanced strand slip from the main tower side tension, anchorage side tension and saddle position detected by the saddle position detection means, and the saddle position A strand slip prevention device in a suspension bridge side tower saddle part, comprising: saddle positioning means for controlling the moving means so as to move the saddle to the saddle position obtained by the computing means.

According to the present invention, in the device for preventing the strands from slipping in the suspension bridge side tower saddle section having the above-mentioned structure, the saddle position detecting means is arranged to displace the predetermined position of the side tower top section with respect to the reference vertical line of the suspension bridge side tower. , And a relative position relationship between the saddle and the top of the suspension bridge side tower, and obtains the absolute position of the saddle.

According to the present invention, in the device for preventing strand slippage in the suspension bridge side tower saddle portion having the above-mentioned structure, the tension calculating means has the temperature of the cable strands extending from the side tower to the main tower side and the anchorage side on the left and right sides respectively. And the strand tension is calculated from the relation between the main tower side and the anchorage side, which is the known amount between the strand lengths in the spans.

[0013]

According to the present invention having the above-mentioned solution means, the saddle provided at the top of the suspension bridge side tower is formed into a movable structure that can move in the longitudinal direction of the cable strand around which the saddle is stretched.
It is configured to be forcibly moved in the longitudinal direction by a moving unit including a drive source such as a motor. On the other hand, the position of the saddle and the tensions of the cable strands extending from the side tower to the main tower side and the anchorage side on the left and right sides are constantly monitored. Then, a saddle position that does not cause strand slip due to a balance between the stresses of the left and right cable strands is obtained from the monitoring data, and the saddle is always forcibly moved to the obtained saddle position. As a result, the saddle is always placed at a position where the stress of the left and right cable strands is balanced, and the cable erection can be effectively prevented, including during the work of stretching the strand, while effectively preventing strand slip in the suspension bridge side tower saddle. It is possible to rationally proceed in a stable state, and it is possible to deal with a small pressing device or a strand pressing device is not required when the cable is installed.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic side view of a side tower type suspension bridge. A pair of main towers 1 are body-standing with a center span 2, and a main tower saddle 1A is provided at the top. In this example, the side tower 3 has a side span 5 and a backstay span 6 between one of the main tower 1 and the anchorage 4, and is pivotally supported on the abutment 11 in a vertical shape. Is equipped with a side tower saddle 3A.

7 is the main cable, 8 is the catwalk,
Reference numeral 10 denotes a storm rope, and the main cable 7 is connected and fixed to the anchorage 4 via the main tower saddle 1A, the side tower saddle 3A, and the spray saddle 9.

An outline of the cable erection method for this side tower type suspension bridge will be described below. The strand reel is set on an anchorer (not shown) placed on one of the anchorages 4, passes through rollers arranged on the catwalk 8, and goes from the anchorages 4 to the other anchorages 4 by, for example, a holing method. The strands are pulled out, shaped into a predetermined cross-sectional shape at the positions of the saddles, and stored in the predetermined positions within the saddles. It should be noted that these series of operations are performed in the daytime. Then, the sag is adjusted according to the reference strand in a time zone when the temperature at night is stable, and a predetermined strand straddling shape is formed. This process is repeated as many times as the number of strands of the two main cables 7, and after laying all the strands, a cable having a circular cross section is finished by using a hydraulic squeeze machine. After that, erection of cable band, catwalk 8 refill,
Cable erection is completed after hanger rope erection and cable anticorrosion work.

2 and subsequent figures, an outline of a strand slip prevention device according to an embodiment of the present invention in the suspension bridge side tower saddle portion of FIG. 1 is shown as a structural diagram, and FIG. 2 is an overall system diagram, FIG. 3 is a plan view of the side tower saddle 3A portion shown in FIG. 2, FIG. 4 is a right side view of the side tower saddle 3A portion, and FIG. 5 is the same as the arrow line A in FIG. FIG. 6 is a front view and FIG. 6 is a view B of the side tower saddle 3A portion in FIG.
FIG. The top end 21 of the top of the side tower 3 is formed on a smooth, water-flat surface, and a pair of recessed grooves 22 are parallel to the left and right sides of the main cable 7 to be laid along the longitudinal direction of the strand 12. Is recessed in.

The side tower saddle 3A is formed into a trough-shaped body having a generally U-shaped cross section so that the strands 12 are inserted in the recess, and the base of the saddle 3A has the axis of the recess. A pair of protrusions 23 extending in parallel are provided so as to project downward, and the side tower saddle 3A is mounted on the top end 21 in a state in which the protrusions 23 are fitted in the recess grooves 22. The side tower saddle 3A thus provided is
By fitting the ridges 23 and the groove grooves 22,
It is slidable only on the top end 21 in the axial direction of the recess, that is, in the longitudinal direction of the strand 12. A fluororesin (PTFE) plate 24 is inserted between the sliding contact surfaces of the ridges 23 and the groove 22 to minimize the frictional resistance between the ridges 23 and the groove 22. The side tower saddle 3A can slide smoothly and lightly. In this case, the member for reducing the frictional resistance is not limited to the fluororesin plate 24,
Besides, it is of course possible to substitute a different plate made of a material having a small frictional resistance.

The side tower saddle 3A is connected to a moving means 25 realized by a saddle horizontal moving device. The saddle horizontal moving device 25 is attached to the top of the side tower 3 and is attached to the side tower saddle 3.
A moving screw jack 26 connected to A, a speed reducer 28 having an output shaft connected to the screw portion of the jack 26 and attached to the top of the side tower 3, and a reduction gear 28 connected to the speed reducer 28 and attached to the top of the side tower 3. And the side tower saddle 3 by reversibly driving the motor 27.
A is moved along the longitudinal direction of the strand 12 toward the main tower 1 side and the anchorage 4 side.

A temporary saddle 31 is further coaxially connected to the end of the side tower saddle 3A on the main tower 1 side, and
Strand pressing device 29 for the upper surface of the saddle is the side tower saddle 3A
The saddle side strand holding device 30 is attached to each temporary saddle 31. Both of the strand pressing devices 29 and 30 are devices used for fixing the strands 12 during erection, and have a well-known structure including a frame and a hydraulic slide jack, and are relatively small in size depending on the purpose of use. The structure of is sufficient.

The mechanism of the strand slip prevention device according to this embodiment is as described above, and controls the saddle horizontal movement device 25, the saddle upper surface strand pressing device 29, and the saddle side surface strand pressing device 30. The electric circuit system and the hydraulic circuit system, which are systems, are connected as shown in FIG. That is, the saddle horizontal movement device 25
A control panel 32, a temperature measuring unit 33, etc. are arranged in association with the motor 27 of the
Hydraulic unit 3 in connection with 30 hydraulic slide jacks
4 and the like are provided. Control panel 32 and temperature measuring unit 33
Is an apparatus for realizing each element of the saddle position detecting means, the tension calculating means, the saddle position calculating means, and the saddle positioning means, which are the constituent requirements of the electric control system in the present embodiment, and the specific aspects thereof are illustrated in FIG. 7, which will be clarified by the description below with reference to FIG.

FIG. 7 shows a block diagram of an electric control system according to the embodiment, and FIG. 8 shows a flowchart for explaining the operation of automatic control. 2 and 7, a stroke sensor 35, which is a detector for detecting the position of the saddle 3A with respect to the reference point of the side tower 3, is attached to the side tower saddle 3A. The position signal from 35 is introduced into the position calculation circuit 37. In this position calculation circuit 37, the displacement of a predetermined position of the top part of the side tower 3 with respect to the reference vertical line of the side tower 3 (it is possible to measure directly by a laser vertical device provided at the base of the side tower 3 or the like) and the side tower saddle 3A The absolute position of the side tower saddle 3A is calculated from the relative positional relationship between the side tower and the top of the side tower 3. The stroke sensor 35 and the position calculation circuit 37 constitute the saddle position detecting means 13.

Strand 1 near the side tower saddle 3A
2 has a temperature measuring sensor 36 embedded or attached,
The temperature signal from the temperature measuring sensor 36 is used as the tension calculation circuit 38.
Will be introduced to. In the tension calculation circuit 38, the length of the inner span strand 12 on the side of the main tower 1 and the length of the inner strand 12 on the anchorage 4 side which are known quantities with respect to the reference temperature, and the side of the main tower 1 which is a variable with respect to the temperature signal. The current main tower 1 side strand tension and anchorage 4 side strand tension are calculated from the length of the inner span strand 12 and the length of the inner span strand 12 on the anchorage 4 side. The temperature calculation sensor 36 and the tension calculation circuit 38 constitute the tension calculation means 14.

Position calculation circuit 37 and tension calculation circuit 38
The saddle position signal, the strand tension signal signal on the main tower 1 side, and the strand tension signal on the anchorage 4 side, which are derived from, are guided to the saddle position calculation means 15. The saddle position calculating means 15 calculates a saddle position where the tensions of both strands can be balanced from the signals, and outputs the saddle position signal to the saddle positioning means 16 in the subsequent stage as a saddle position signal.

The saddle positioning means is composed of an electric circuit having a power amplification circuit as an element, and the motor 27 is arranged so that the current side tower saddle 3A position matches the saddle position signal introduced from the saddle position calculating means 15. Drive output to the side tower saddle 3A via the screw jack 26.
Is moved to the main tower 1 side or the anchorage 4 side.

Next, the mode of horizontal movement control of the side tower saddle 3A performed to prevent the strands from slipping in this embodiment will be described below with reference to FIG. When the control system of the strand slip prevention device starts automatic control in step S1, the process proceeds to the next step S2, and the start value of the side tower saddle 3A is a target value (a saddle obtained by calculation corresponding to the reference temperature). The position is checked to see if it matches. The "start value" in this case means the position of the side tower saddle 3A at the time of automatic mode switching, that is, the saddle position detecting means 1
3 is a saddle position signal (measurement value) output, for example, the displacement of the top of the side tower 3 is measured by a laser vertical instrument, and the relative position between the side tower saddle 3A and the top of the side tower 3 is measured by the stroke sensor 35. The absolute position of the saddle can be obtained by measuring the value in step S1 and polymerizing the two. When it is checked that the start value of the side tower saddle 3A matches the target value, the process goes to step S3, the control system is switched to the automatic correction mode, and the automatic control operation is started.

Next, in step S4, the tension calculating means 14 first compares the temperature difference determined from the current temperature of the side tower saddle 3A with the set value. Here, the temperature difference is the absolute value of the difference between the current value and the previous value (the temperature when the control was applied last time). If the comparison result is temperature difference ≧ setting value, the process proceeds to step S5, and a correction start command is issued, whereby the tension calculation means 14 calculates the tension, and the saddle position calculation means 15 calculates the saddle position where the tension balances. After that, the process proceeds to step S6, the saddle horizontal moving device 25 is driven by the saddle positioning means 16, and at the same time, the current value of the side tower saddle 3A is compared with the target value in step S7. Done. Then, when the current value of the side tower saddle 3A matches the target value, the process proceeds to step S8 and the automatic control for correction is completed. In this way, the side tower saddle 3A is always automatically controlled to move to a position where no slip occurs with the strand 12.

Incidentally, in step S2, the side tower saddle 3
If the start value of A does not match the target value, skip to step S5 and start correction, saddle movement, and comparison of the saddle position current value with the target value in order until the start value matches the target value. The automatic correction mode. Further, the automatic control operation is usually performed by the temperature of the strand, but of course the control may be performed by the air temperature in the vicinity of the side tower 3.

By the way, the position of the side tower saddle 3A is detected by
In addition to the detection method in the above embodiment, it is also possible to directly measure with an optical distance measuring instrument set at a coordinate known point such as anchorage, and such detection means is also included in the scope of the present invention. It On the other hand, Strand 12
In order to detect the tension of the strands, it is of course possible to attach a strain gauge to the strand 12 and directly measure the tension, or to attach a dummy strand and indirectly detect the tension. In the example, since the method of detecting the tension by the cross-section temperature of the strand is simple, such a method is adopted, and the adoption of the direct tension detecting method is naturally included in the scope of the present invention. .
To determine the change in cable tension, especially horizontal tension, use the formula for calculating the change in cable length due to temperature changes in a parabolic cable stretched between the left and right fulcrums, and the change in cable descent. Although it is easily obtained by a calculation formula for obtaining a change in horizontal tension, it is possible to obtain a stricter value based on the catenary formula regarding catenary.

Further, in order to measure the temperature of the strand 12, in addition to an example in which an appropriate one is selected at one location near the side tower saddle 3A and the temperature is directly measured by the temperature sensor, a plurality of strands are measured at the same location. Select the temperature and measure the temperature directly with the temperature measuring sensor and obtain the average value, or
It is of course possible to use a measuring means such as selecting several points dispersed in the longitudinal direction of 2 and measuring the temperature by the same method to obtain the average value.

[0031]

As described in detail above, according to the present invention, the side tower saddle is always forcibly moved to an appropriate position where the strand tension is balanced between the left and right side towers so as to follow the minute temperature change of the strand. Since it is also a device, the side tower saddle acts directly and effectively in the longitudinal direction of the cable strand, which is closer to the direction of the slip force generation, rather than the vertical action direction as in the conventional pressing device, so it is extremely efficient. It is possible to deal with slip with compact equipment. Further, the present invention can reliably deal with strand slip at the top of the side tower by using only the side tower saddle or by supplementarily using a small strand pressing device for this, so that cable erection work can be performed. The rationalization and cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic side view of a side tower type suspension bridge.

FIG. 2 is a system diagram showing the overall structure of a strand slip prevention device according to an embodiment of the present invention.

FIG. 3 is a plan view of a side tower saddle 3A portion shown in FIG.

FIG. 4 is a right side view of a side tower saddle 3A portion shown in FIG.

5 is a front view taken along a line A in FIG.

FIG. 6 is a front view taken along line B in FIG.

FIG. 7 is a block diagram showing a block diagram of an electric control system in a strand slip prevention device according to an embodiment of the present invention.

FIG. 8 is a flow chart illustrating an automatic control operation in the strand slip prevention device according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Main tower, 1A ... Main tower saddle, 2 ... Center span, 3 ... Side tower, 3A ... Side tower saddle, 4 ... Anchorage, 5 ... Side span, 6 ... Backstay span, 7 ... Main cable, 8 ...
Catwalk, 9 ... Spray saddle, 10 ... Storm rope, 11 ... Abutment, 12 ... Strand, 13
... saddle position detecting means, 14 ... tension calculating means, 15 ... saddle position calculating means, 16 ... saddle positioning means, 21
... top end, 22 ... concave groove, 23 ... convex stripe, 24 ... fluororesin plate, 25 ... moving means, 26 ... moving screw jack, 27 ... motor, 28 ... reducer, 29 ... upper strand pressing device, 30 ... Side strand pressing device, 31 ... Temporary saddle, 32 ... Control panel, 33
... temperature measuring unit, 34 ... hydraulic unit, 35 ... stroke sensor, 36 ... temperature measuring sensor, 37 ... position calculation circuit, 38 ... tension calculation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Sugii 1-3-18 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel Works, Kobe Head Office (72) Masao Hirosawa Wakihama, Chuo-ku, Kobe-shi, Hyogo 1-3-18 Machi Kobe Steel Co., Ltd. Kobe Head Office (72) Inventor Hiroshiro Tsutsuka 2-6-3 Otemachi, Chiyoda-ku, Tokyo Shin Nippon Steel Co., Ltd. Head Office (72) Inventor Toru Honma 2-3-6 Otemachi, Chiyoda-ku, Tokyo In-house Nippon Steel Co., Ltd. (72) Inventor Atsushi Takubo 3-5-26, Himejima, Nishiyodogawa-ku, Osaka Okumura Machinery Co., Ltd. (72) In-house Koji Nishimura 1-14 Irie-cho, Muroran-shi, Hokkaido Within the Muroran Development and Construction Department, Hokkaido Development Bureau (72) Inventor Hirohide Kiyomi 1-14 Irie-cho, Muroran-shi, Hokkaido Hokkaido Development Bureau Murora Kai Construction portion

Claims (4)

[Claims] 1. A suspension structure provided on the top of a suspension bridge side tower is provided with a movable structure capable of moving in the longitudinal direction of a cable strand stretched over the saddle, and the position of this saddle and the main tower side and anchorage on both left and right sides of the side tower. While monitoring the tension of each cable strand extending to the side and, while seeking the saddle position that does not cause strand slip by balancing the stress of the left and right cable strands, characterized in that the saddle is always forcibly moved to the saddle position A method for preventing strand slippage in the saddle part of the suspension bridge side tower. 2. A saddle provided at the top of the suspension bridge side tower so as to be horizontally movable in the longitudinal direction of the cable strand to be stretched, and a moving means connected to the saddle and forcibly moving the saddle in the longitudinal direction of the cable strand. , A saddle position detecting means for detecting the saddle position as a displacement from the reference point, a tension calculating means for calculating each tension of the cable strands extending from the side tower to the main tower side and the anchorage side on the left and right sides, and a tension calculation Saddle position calculating means for calculating a saddle position at which the stress of the left and right cable strands does not cause balanced strand slip from the main tower side tension, anchorage side tension calculated by the means, and the saddle position detected by the saddle position detecting means; A moving means is provided to move the saddle to the saddle position obtained by the position calculating means. A strand slip prevention device in a suspension bridge side tower saddle part, comprising a saddle positioning means for controlling. 3. The saddle position detecting means measures a displacement of a predetermined position of the side tower top part with respect to a reference vertical line of the suspension bridge side tower, and a relative positional relationship between the saddle and the top end of the suspension bridge side tower, 3. A measuring / calculating means for determining the absolute position of the saddle.
Strand slip prevention device in the suspension bridge side tower saddle section described. 4. The tension calculating means measures the temperature of the cable strands extending from the side tower to the main tower side and the anchorage side on both the left and right sides, and within each span which is a known amount on the main tower side and the anchorage side. The strand slip prevention device in the suspension bridge side tower saddle part according to claim 2 or 3, which comprises a measuring / calculating means for calculating the strand tension from the relationship with the strand length.