JP2002296252A - Method and system for diagnosing fatigue of cantilevered or arch-shaped structure, and amplitude-measuring instrument used for diagnosis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily diagnose fatigue of a cantilevered or arch-shaped structure installed under a vibration environment. SOLUTION: An amplitude measuring instrument 10 is provided in a prescribed portion 3b of a sign post 3 (structure) in an express highway. The level of a displacement amplitude in vibration of the prescribed portion 3b and the number of occurrence is measured over a fixed period by the amplitude measuring instrument 10. A level of a stress amplitude applied onto a dangerous cross- sectional part 3a of the sign post 3 for the fixed period, and the number of occurrence are calculated by a data analyzer (not shown) based on a measured result therein, so as to estimate a fatigue life of the cross-sectional part 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for diagnosing fatigue of a cantilevered or portal-shaped structure (for example, a signpost or a lighting pole on a highway) installed in a vibration environment. And an amplitude measuring instrument used for the diagnosis.

[0002]

2. Description of the Related Art For example, a signpost installed on a highway is
The vehicle may be repeatedly subjected to a load by stress vibration or wind from a traveling vehicle, causing fatigue damage. As a result, cases of sudden collapse have been reported, and this has become an important issue for maintenance and inspection. Recently, fatigue design using fatigue test data and structural design methods has been considered, but the amount of vehicle travel and wind strength differ depending on the installation location, and establishing a design standard that covers all fatigue factors Has not been reached.
Therefore, at actual sites, a strain gauge is attached to a dangerous cross section where fatigue damage is expected on a signpost, a dynamic strain gauge is connected to this strain gauge, and the stress frequency due to rain flow etc. is determined based on the measurement result. Distribution analysis was performed to estimate the remaining life up to fatigue failure.

[0003]

However, in order to attach a strain gauge, a grind must be applied to the sign post. In addition, it is necessary to secure an installation place for the dynamic strain measuring instrument and to prepare a power supply for the measuring instrument, and much labor and cost are required for on-site measurement. Therefore, the measurement has to be limited to a limited number of limited places on the road, and it is difficult to check all of a large number of signposts such as a highway. In addition, the determination of the measurement target requires judgment of an experienced person or the like, and thus lacks versatility and simplicity. The present invention has been made in view of the above circumstances,
The purpose is to enable simple means to diagnose fatigue of cantilevered or portal-shaped structures installed in a vibrating environment, such as signposts,
In addition, it is an object of the present invention to enable a simple and inexpensive fatigue diagnosis of many (plural) structures at the same time.

[0004]

In order to solve the above-mentioned problems, a first feature of the present invention relates to a method for diagnosing fatigue of a cantilevered or portal-shaped structure installed in a vibration environment. . First, an amplitude measuring device is provided at a predetermined portion of the structure. The amplitude measuring device measures the magnitude and the number of occurrences of the displacement amplitude during vibration of the predetermined portion over a certain period. Based on the measurement result, a fatigue diagnosis of the structure is performed. This first
The "fatigue diagnosis" in the feature of "1" includes not only the diagnosis of the "fatigue degree" to be described later but also the diagnosis of whether or not the structure is installed in a place where fatigue is likely.

According to a second feature of the present invention, a stress amplitude acting on a dangerous cross section of the structure during the certain period is determined based on a measurement result of an amplitude measuring device performed in the same manner as the first feature. The size and the number of occurrences are calculated, and the fatigue level of the dangerous cross section is diagnosed. Here, the "fatigue degree" indicates how much the degree of progress of fatigue damage of a structure corresponds to the degree of damage leading to fatigue fracture, and "diagnosing the degree of fatigue""" Includes obtaining a fatigue life from the start of service of the structure to the above-mentioned fatigue rupture, and a remaining life obtained by subtracting the service period from the fatigue life.

A third feature of the present invention relates to a system for diagnosing fatigue of a cantilevered or portal-shaped structure installed in a vibration environment. This diagnostic system includes an amplitude measuring device and an analyzer. The amplitude measuring device is provided at a predetermined portion of the structure, and measures the magnitude and the number of generated displacement amplitudes of the predetermined portion during vibration. The analysis device calculates the magnitude and the number of occurrences of the stress amplitude acting on the dangerous cross section of the structure during the period based on the measurement result of the amplitude measuring device over a certain period, and thus calculates the fatigue life of the dangerous cross section. presume.

[0007] In a fourth aspect of the present invention, the first to third aspects are described.
Wherein the amplitude measuring device according to the feature of (1) senses the actual displacement amplitude of the predetermined portion as any of a plurality of preset displacement amplitudes, and counting means for counting the number of times of sensing for each of the set displacement amplitudes And

According to a fifth feature of the present invention, the first to third aspects are described.
The amplitude measuring device according to the first aspect includes a plurality of sensing units for sensing displacement amplitudes equal to or greater than different settings, and counting means for counting the number of times each sensing unit senses. Fourth,
In the fifth aspect, it is preferable that the amplitude measuring instrument has a mounting portion that is detachable from the structure (a sixth aspect of the present invention).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a viaduct for an expressway. On the balustrade 2, a steel signpost 3 (a cantilevered long structure) is erected. Signpost 3
Has a pillar body 3X, an arm 5 extends horizontally from the upper end of the pillar body 3X, and the sign board 4 is suspended from the arm 5.

The signpost 3 becomes fatigued due to factors specific to the installation location, such as the traveling vehicle and the wind. FIG. 2 shows a fatigue diagnosis system S for diagnosing the degree of fatigue. The fatigue diagnosis system S includes an amplitude measuring device 10 and a data analysis device 20.

The amplitude measuring device 10 has, for example, a structure in which five (plural) measuring units 11A to 11E are connected in a line. A mounting plate 19 (attaching portion) made of a permanent magnet is provided on the back surface of each of the measuring units 11A to 11E so that the attaching plate 19 can be attached to and detached from the steel (magnetic) marker pillar 3 by magnetic force. Has become.

Each of the measuring units 11A to 11E has a case 12. Inside the case 12, a vibrator 13 (a "sensing section" of the fifth feature of the present invention) supported by a spring (not shown) and a counting circuit 14 (counting means) are housed. The vibration input to the case 12 is transmitted to the vibrator 13 via a spring, and the vibrator 13 vibrates. Each time the vibrator 13 makes one reciprocation, it comes into contact with the contact point of the count circuit 14 to output a count-up signal, and the count value of the count circuit 14 is incremented by one. The count value is displayed on a liquid crystal display 15 provided on a front plate of the case 12.

The displacement amplitude threshold values (levels) δ _{1 to} δ ₅ to which the measuring units 11 A to ₁₁ E respond are different from each other. That is, the vibrator 13 of the measuring unit 11A is
When the displacement amplitude of _No. 2 is equal to or greater than δ ₁ (level 1), a count-up signal is output. Similarly,
The vibrator 13 of the measurement unit 11B has δ ₂ (level 2) or more,
The vibrator 13 of the measuring unit 11C has δ ₃ (level 3) or more,
The vibrator 13 of the measuring unit 11D has δ ₄ (level 4) or more,
The transducer 13 of the measuring unit 11E outputs a count-up signal for each displacement amplitude equal to or greater than δ ₅ (level 5). Then, δ ₁ <δ ₂ <δ ₃ <δ ₄ <δ ₅ holds. By synthesizing the presence / absence and the number of times of sensitivity of these five transducers 13, the magnitude of the displacement amplitude input to the case 12 and the number of occurrences of the displacement amplitude can be measured.

The data analysis device 20 is composed of, for example, a personal computer, and has an input unit 21 for inputting a measurement result of the amplitude sensor 10 and the like, a processing unit 22 for performing a fatigue analysis based on the input data, and a storage unit 23. And a CRT 24 (display unit) for displaying the analysis result. The storage unit 23 stores the SN (stress-
Material data necessary for fatigue analysis such as (repeated) diagram data is stored in advance.

A description will be given of a method of performing a fatigue diagnosis of the signpost 3 using the fatigue diagnostic system configured as described above. It is mainly at the dangerous cross section 3a (FIG. 1) at the base end (fixed end) of the pillar main body 3X that the fatigue fracture is expected in the signpost 3. The amplitude measuring device 10 is attached to the measurement site 3b (predetermined site) that is separated from the dangerous cross section 3a by a distance H. At this time, only by attaching the mounting plate 19 to the signpost 3, the two stick together by magnetic force, and the mounting operation can be performed extremely simply and quickly.

When the signpost 3 vibrates due to the running vehicle or the wind, the amplitude measuring device 10 also vibrates together with it. Then, if the displacement amplitude of the measured region 3b, for example, [delta] ₅ above, all five of the transducer 13 is sensitive to the measurement unit 1 IA to, each one reciprocation of the count values of the measuring unit 1 IA to vibration Is incremented by one. If the displacement amplitude [delta] ₄ or more, the measurement unit 11A~11D is counted up. If the displacement amplitude [delta] ₃ or more, the measuring unit 11A~11
C is counted up. If the displacement amplitude [delta] ₂ or more, the measurement unit 11A, 11B is counted up. If the displacement amplitude [delta] ₁ or more, only one measurement unit 11A is counted up. And each measurement part 11A-11
E on the liquid crystal display 15 with the measuring units 11A to 11
The cumulative number of displacement amplitudes counted by E is displayed. Incidentally, when the displacement amplitude of the measured region 3b is less than [delta] ₁ is 5
One of the measuring part is both insensitive of 1 IA to, stress amplitudes acting on the dangerous cross section 3a during displacement amplitude of the δ less than _1, less than the fatigue limit, does not affect the fatigue diagnosis.

In this way, the measurement is performed over, for example, two months. The accumulated count values of the measuring units 11A to 11E after two months have passed are, for example, N ₁ for the measuring unit 11A,
B is N ₂ , the measurement unit 11C is N ₃ , the measurement unit 11D is N ₄ ,
Measuring unit 11E is assumed to be _{N 5.}

After the measurement period, the amplitude measuring device 10 is removed from the marker pillar 3. And five measuring units 11A-1
The count value N displayed on the liquid crystal display 15 of 1E
₁ to N ₅ and, in the measuring unit 11A~11E threshold δ ₁ ~δ
₅ , the distance H between the dangerous cross-section 3a and the measurement site 3b
Alternatively, measurement data such as a measurement period T = 2 months is input to the input unit 21 of the data analysis device 20. In addition, the operating period from the time when the signpost 3 is set to the viaduct 1 to the present is also input.

Upon receiving the data input, the processing section 22
Diagnose the degree of fatigue of 3. That is, during the measurement period T,
The displacement amplitude of the measuring unit 3b is δ₁N times_δ1Is N_δ1= N₁− (N₂+ N₃+ N₄+ N₅). Similarly, the displacement amplitude δ₂
Number of times N_δ2Is N_δ2= N₂− (N₃+ N₄+ N₅), And the displacement amplitude δ₃Number of times N
_δ3Is N_δ3= N₃− (N₄+ N₅), And the displacement amplitude δ₄Number of times N
_δ4Is N_δ4= N₄-N₅, And the displacement amplitude δ₅Number of times N
_δ5Is N_δ5= N₅  Can be sought. Signpost 3 vibrates and is measured
Each time the part 3b is displaced, a stress is applied to the dangerous section 3a.
Acts, the above displacement amplitude δ₁~ Δ₅Occurrences
N_δ1~ N_δ5Is the stress amplitude σ at the dangerous cross section 3a₁~
σ₅Also occurs.

The displacement amplitude of the measured portion 3b is δ ₁
Stress amplitude sigma ₄ when dangerous cross section stress amplitude sigma ₁ acting _3a, displacement amplitude [delta] stress amplitude sigma ₂ when the _2, displacement amplitude [delta] ₃ stress amplitude sigma ₃ when _the, the displacement amplitude [delta] ₄ in the case of , The stress amplitude σ ₅ at the displacement amplitude δ ₅ can be obtained by using a stress analysis method such as a finite element method.

In this manner, the magnitudes σ ₁ to σ ₅ and the number of occurrences N _{δ1 to} N _{δ5 of} the stress amplitude generated in the dangerous cross section 3a during the measurement period T can be calculated. As shown in FIG.
This calculation result can be displayed on the CRT 24 as a stress frequency distribution diagram.

Thereafter, by using a known analysis method, the calculation result and the S-value stored in the storage unit 23 are stored.
Based on material data such as an N diagram, it is possible to estimate the degree of fatigue of the dangerous cross section 3a during the measurement period T, and thus to estimate the fatigue life of the dangerous cross section 3a. Then, by subtracting the service period of the sign post 3 from the fatigue life, the remaining life up to the fatigue failure can be obtained. The obtained fatigue life and remaining life are measured by CRT
24 is displayed. Thus, before the signpost 3 is over and its life has expired, it is possible to take measures such as reinforcing and repairing it or installing it again on a new one.

Next, another embodiment of the present invention will be described.
As shown in FIG. 4, in this embodiment, the amplitude measuring device 1
0 ′ has, for example, one piezoelectric element 16 and one processing circuit 17 instead of the plurality of oscillators 13 and the plurality of counter circuits 14 in the first embodiment. The piezoelectric element 16 detects the displacement amplitude of the case 12 and thus the sign post 3 and converts it into a voltage. The processing circuit 17 includes the sensing circuit unit 1
7a and a counting circuit 17b (counting means). The sensing circuit portion 17a cooperates with the piezoelectric element 16 to constitute a "sensing portion" according to the fourth feature of the present invention. The sensing circuit unit 17a corrects the converted voltage to one of a plurality of preset voltages according to the magnitude thereof (the sensing unit detects the actual displacement amplitude by a plurality of preset voltages). This is sensed as one of the displacement amplitudes) and input to the count circuit unit 17b. The count circuit unit 17b counts the number of times of inputting the voltage (ie, the number of displacement amplitudes) for each magnitude of the input voltage (ie, the set displacement amplitude). The count result is displayed on the liquid crystal display 15 for each set displacement amplitude. According to this embodiment, the measuring instrument 10 'can be made more compact. Further, the number of set displacement amplitudes can be increased, and more detailed fatigue diagnosis can be performed.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, the target structures for fatigue diagnosis are not only signposts, but also vertically cantilevered pillars such as lighting poles and tall poles, as well as horizontally cantilevered beams and oblique beams. The present invention can also be applied to a cantilever shape extending in the direction. Further, the present invention is not limited to a cantilever shape, and can be applied to a gate-shaped structure including two pillar portions and a beam portion bridged between their tip portions. In this case, for example, by providing the amplitude measuring device according to the present invention in the middle of the pillar, fatigue diagnosis of the base end (dangerous cross section) of the pillar can be performed, and By providing the amplitude measuring device according to the present invention, it is possible to perform a fatigue diagnosis of both ends (dangerous cross section) of the beam. In the sign post 3 shown in FIG. 1, amplitude measuring devices 10 and 10 'are provided at predetermined portions of the arm 5, and a fatigue diagnosis of a base end portion (a connection portion with the column main body 3X) which is a dangerous cross section of the arm 5 is performed. You can also.

The dangerous cross section is not limited to a single location near the fixed end of the cantilever or portal structure. A single structure may have more than one dangerous cross section. The fatigue diagnosis of the present invention can be performed for each dangerous cross section.

A storage means such as a memory card is stored in the amplitude measuring devices 10 and 10 ', the count value of the displacement amplitude is stored in the storage means, and the stored information is stored in the data analyzer 20.
It may be made to be able to read by. A small storage capacity of the storage means is sufficient. In addition, an analysis function for fatigue diagnosis may be built in the amplitude measuring devices 10 and 10 ′.

The mounting portion for detachably attaching the amplitude measuring instrument to the structure has an annular shape with one notch in the circumferential direction. After this annular body is fitted on the outer periphery of the structure, it is notched with a screw or the like. By narrowing the portion, it may be possible to attach to a structure. Further, the band may be wound around a structure.

An amplitude measuring device is attached to each of a large number of cantilever-like or portal-type structures (for example, all signposts and lighting poles installed on one bridge). (For example, many large displacement amplitudes occur)
By judging whether or not it is installed in a place (fatigue diagnosis), several (for example, two or three) structures that are particularly likely to be fatigued and considered dangerous are specified, and the specified structures are determined. Only a detailed measurement using a conventional strain gauge may be performed. Since what is considered to be dangerous may be specified, for example, the one having a large number of large displacement amplitudes may be selected, it can be easily performed even by a specialist in strain measurement. In this case, the fatigue diagnosis by the amplitude measuring device of the present invention is positioned as a rough diagnosis. By this rough diagnosis, it is possible to narrow down the targets of strain measurement (precision diagnosis) that require many steps to a small number from many.

[0029]

As described above, the first to third aspects of the present invention are described.
According to the feature of (1), fatigue diagnosis of a cantilevered or portal-shaped structure installed in a vibration environment can be easily performed, and the cost for measurement and the number of man-hours can be significantly reduced. According to the fourth aspect of the present invention, the amplitude measuring instrument can be made compact. According to the fifth aspect of the present invention, the amplitude measuring instrument can have a simple configuration. According to the sixth aspect of the present invention, the amplitude measuring instrument can be easily attached to and detached from the structure to be diagnosed.

[Brief description of the drawings]

FIG. 1 is a front view according to an embodiment of the present invention in a state where an amplitude measuring instrument is attached to a marker pillar of a viaduct.

FIG. 2 is a schematic configuration diagram of a fatigue diagnosis system according to the embodiment.

FIG. 3 is a stress frequency distribution diagram showing the relationship between the magnitude of stress amplitude and the number of occurrences obtained during the analysis of the degree of fatigue.

FIG. 4 is a front view of an amplitude measuring instrument according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 Signpost 3a Dangerous cross section 3b Measured part (predetermined part) 10, 10 'Amplitude measuring device 13 Vibrator (sensing part) 14 Counter circuit (counting means) 19 Mounting plate (mounting part) 20 Data analyzer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kentaro Yamada 22-70-C, Tashirocho, Chigusa-ku, Nagoya-shi, Aichi C-72 Reference) 2D064 AA11 AA22 BA01 BA19 2G047 AA07 AB01 BA04 BC03 BC11 CA01 EA14 EA16 GG06 GG33 2G064 AA05 AB02 AB24 BA02 BA28 BD18 CC13 CC28 CC55 DD06

Claims (6)

[Claims] An amplitude measuring device is provided at a predetermined portion of a cantilevered or portal-shaped structure installed in a vibration environment, and the amplitude measuring device generates and generates a displacement amplitude when the predetermined portion vibrates. A method for diagnosing fatigue of a cantilever or portal structure, wherein the number is measured over a certain period of time, and a fatigue diagnosis of the structure is performed based on the measurement result. 2. A method for diagnosing fatigue of a cantilevered or portal-shaped structure installed in a vibration environment, comprising: providing an amplitude measuring device at a predetermined portion of the structure; The magnitude of the displacement amplitude and the number of occurrences during the vibration of the predetermined portion are measured over a certain period, and the magnitude and the number of occurrences of the stress amplitude applied to the dangerous cross section of the structure during the certain period are measured based on the measurement results. A fatigue diagnosis method for a cantilever or portal-shaped structure, comprising calculating and eventually diagnosing the degree of fatigue of the dangerous cross section. 3. A system for diagnosing fatigue of a cantilevered or portal-shaped structure installed in a vibration environment, wherein said system is provided at a predetermined portion of said structure, and said predetermined portion is displaced during vibration. An amplitude measuring device for measuring the magnitude and the number of occurrences of the amplitude, and calculating the magnitude and the number of occurrences of the stress amplitude applied to the dangerous cross section of the structure during the period based on the measurement results of the amplitude measuring device over a certain period. And an analysis device for estimating the fatigue life of the dangerous cross-section. 4. An amplitude measuring device in the fatigue diagnosis method according to claim 1 or 2 or the fatigue diagnosis system according to claim 3, wherein a plurality of displacement amplitudes in which actual displacement amplitudes of the predetermined portion are set in advance. And a counting means for counting the number of times of detection for each of the set displacement amplitudes. 5. An amplitude measuring instrument in the fatigue diagnosis method according to claim 1 or 2 or the fatigue diagnosis system according to claim 3, wherein a plurality of sensing units sensing displacement amplitudes equal to or greater than different settings. An amplitude measuring instrument for fatigue diagnosis, comprising: counting means for counting the number of times of sensing by each sensing section. 6. An amplitude measuring instrument for fatigue diagnosis according to claim 4, wherein said structure has a detachable mounting portion.