Cable health assessment system, method, program, recording medium, and device

Abstract

Vibration information is obtained via radio waves from cables installed in cable-stayed bridges, etc., to ensure safe and rapid processing. [Solution] A health evaluation system for an installed cable, comprising a radar (vibration visualization radar unit 14) that transmits radio waves (Si) toward the cable (10), receives reflected waves (Sr) from the cable, and acquires power spectrum information from the reflected waves, and a health evaluation unit (18) that calculates the cable tension (T) using the natural vibration frequency (fi) extracted from the power spectrum information, and compares this tension with the design tension (Tm) to evaluate the health of the cable.

Description

[Technical Field]

[0001] The present disclosure relates to an evaluation technique for evaluating the soundness of a cable in a non-contact manner, for example, in a cable-stayed bridge that includes a cable. [Background technology]

[0002] Cable-stayed bridges consist of multiple cables that support the bridge. Therefore, to ensure the safety of the bridge, their integrity is evaluated periodically.

[0003] Regarding the evaluation of this soundness, it is known to acquire image data of the cable surface, generate eddy currents in the cable to measure the impedance, and use the image data in combination to inspect the cable for damage or breakage in an unmanned manner (for example, Patent Document 1).

[0004] Regarding vibration measurement of civil engineering and architectural structures such as bridges, it is known that a point on the structure where the brightness changes or a point where there is a clear difference in brightness from the background is photographed, and this point of interest is recognized as a point of change in the shade of pixels on the image and recorded as a time change point, and the natural frequency of the structure is identified from this record (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-166750 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-162096 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional tension measurements, used to assess the soundness of tensile cables such as cable-stayed bridges, involve applying vibrations to the cable-stayed bridge cable equipped with an accelerometer (excitation processing), measuring the acceleration response from the cable, and obtaining acceleration data. This acceleration data is then subjected to spectral analysis to determine the natural vibration frequency, which is then used to calculate the tension. This tension is then compared with the design tension, or the calculated tension with the previous calculated tension, and the soundness of the cable is assessed using these comparison results.

[0007] Previous tension measurements had challenges, such as traffic restrictions on expressways over which cable-stayed bridges were built, the need for workers at height to install accelerometers on the cables, the need to avoid the risk of work vehicles being rear-ended by ordinary vehicles, and the time and expense required for tension analysis, which was time-consuming and laborious to process.

[0008] Therefore, based on the above-mentioned problems, the object of the present disclosure is to evaluate the soundness of cables using vibration information obtained by radio waves from cables installed in cable-stayed bridges, etc., and to ensure safe and rapid processing. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, according to one aspect of the cable health evaluation system of the present disclosure, there is provided a system for evaluating the health of a tensioned cable, which includes a radar that transmits radio waves toward the cable, receives reflected waves from the cable, and acquires power spectrum information from the reflected waves, and a health evaluation unit that calculates the tension of the cable using the natural vibration frequency extracted from the power spectrum information, and compares this tension with a design tension to evaluate the health of the cable.

[0010] This cable health evaluation system may further include a temperature measurement unit that measures the temperature of the cable, and the health evaluation unit may correct the tension or the design tension based on the temperature information of the cable, and evaluate the health of the cable using the corrected tension or the design tension.

[0011] In this cable health evaluation system, the health evaluation unit may compare the tension with the design tension to determine the difference between the tension and the design tension, and evaluate the health based on whether this difference is within a reference range.

[0012] In this cable health evaluation system, the radar may be installed in a location with little shaking to transmit the radio waves and receive the reflected waves, and the health evaluation unit may calculate the tension using the natural vibration frequency obtained according to the shaking state of the cable.

[0013] In this cable health evaluation system, the health evaluation unit calculates the following relational expression (Equation 1):

number

[0014] In order to achieve the above-mentioned object, according to one aspect of the cable health evaluation method of the present disclosure, there is provided a method for evaluating the health of a tensioned cable, comprising the steps of: a radar transmitting radio waves toward the cable and acquiring power spectrum information from the reflected waves received from the cable; and a health evaluation unit calculating the tension of the cable using the natural vibration frequency extracted from the power spectrum information, and comparing this tension with a design tension to evaluate the health of the cable.

[0015] This cable health evaluation method may further include the steps of: a temperature measurement unit measuring the temperature of the cable; and the health evaluation unit correcting the tension or the design tension using temperature information acquired from the temperature measurement unit, and evaluating the health of the cable using the corrected tension or the design tension.

[0016] This cable health evaluation method may include a step in which the health evaluation unit compares the tension with the design tension to determine the difference between the tension and the design tension, and evaluates the health based on whether this difference is within a reference range. The cable health evaluation method according to claim 6 or 7,

[0017] This cable health evaluation method may further include a step in which the radar transmits radio waves in a location with little shaking and acquires the reflected waves from the cable, and a step in which the health evaluation unit calculates the tension using the natural vibration frequency acquired according to the shaking state of the cable.

[0018] In this cable health evaluation method, Health Assessment The part is expressed by the following relation (Equation 1):

number

[0019] In order to achieve the above-mentioned object, according to one aspect of the cable health evaluation method of the present disclosure, there is provided a method for evaluating the health of a tensioned cable, comprising the steps of: transmitting radio waves toward the cable, receiving reflected waves from the cable, acquiring power spectrum information from the reflected waves using a radar to obtain the natural vibration frequency of the cable, and obtaining the tension of the cable using the natural vibration frequency; acquiring vibration information from the cable without using the radar and obtaining the tension of the cable using the vibration information; verifying the tension obtained using the radar by comparing it with the tension obtained without using the radar; and evaluating the health of the cable by comparing the tension obtained using the radar with a design tension.

[0020] In order to achieve the above object, according to one aspect of the cable program of the present disclosure, a computer is caused to execute the following functions: a function of transmitting radio waves from a radar toward a cable and acquiring power spectrum information from the reflected waves received from the cable using the radar; a function of extracting a natural vibration frequency from the power spectrum information using a natural vibration frequency extraction unit; a function of calculating the tension of the cable using the natural vibration frequency using a tension calculation unit; and a function of evaluating the soundness of the cable by comparing the tension with a design tension using a soundness evaluation unit.

[0021] This program may further cause the computer to perform the following functions: acquiring temperature information of the cable; correcting the tension or the design tension using the temperature information; and evaluating the soundness of the cable using the corrected tension or the design tension.

[0022] This program may further cause the computer to execute a function of comparing the tension with the design tension to determine the difference between the tension and the design tension, and evaluating the soundness of the cable based on whether or not this difference is within a reference range.

[0023] This program may further cause the computer to execute a function of transmitting the radio waves to a radar installed in a location with little shaking and acquiring the reflected waves from the cable, and a function of causing the tension calculation unit to calculate the tension using the natural vibration frequency acquired according to the shaking state of the cable.

[0024] In this program, the computer further calculates the following relation (Equation 1):

number

[0025] To achieve the above object, one aspect of a recording medium of the present disclosure is a recording medium storing the program.

[0026] In order to achieve the above object, according to one aspect of the cable health evaluation device of the present disclosure, the device is a health evaluation device for a tensioned cable, and includes: a radar that transmits radio waves toward the cable and receives reflected waves from the cable to obtain power spectrum information; a health evaluation unit that extracts a natural vibration frequency from the power spectrum information, calculates the tension of the cable using this natural vibration frequency, and evaluates the health of the cable by comparing this tension with a design tension; and an information presentation unit that presents evaluation information representing the health evaluation results. [Effects of the Invention]

[0027] According to the present disclosure, any of the following effects can be obtained. (1) The tension of cables installed in cable-stayed bridges, etc., can be measured without contact with the cables, and the integrity of the cables can be evaluated by comparing them with the design tension.

[0028] (2) The cable tension can be measured at a location separate from the installed cable, shortening analysis time and improving the accuracy of cable health assessment, thereby improving measurement efficiency and safety.

[0029] (3) Traffic restrictions on expressways where cable-stayed bridges are installed, for example, can be alleviated; there is no need for workers at height to install accelerometers on cable-stayed bridge cables, which reduces the time and cost required for the work; the risk of rear-end collisions with ordinary vehicles can be avoided; the time and cost required for tension analysis can be reduced; and tension measurement and soundness assessment can be speeded up. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1A is a diagram showing a soundness assessment system and a cable-stayed bridge, and FIG. 1B is a diagram showing the relationship between the soundness assessment system and the cables. [Figure 2] FIG. 2 is a block diagram showing a health assessment system according to one embodiment. [Figure 3]FIG. 3 is a diagram illustrating an example of the evaluation information database. [Figure 4] FIG. 4 is a flowchart showing the processing procedure of the soundness evaluation system. [Figure 5] FIG. 5 is a flowchart illustrating a procedure for evaluating the soundness of a cable according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating a graph of vibration information according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing power spectrum information and first to nth order natural vibration frequencies according to the second embodiment. [Figure 8] FIG. 8 is a flowchart illustrating a procedure for temperature correction according to the third embodiment. [Figure 9] FIG. 9 is a diagram showing an example of the correction tension table. [Figure 10] FIG. 10 is a diagram illustrating an example of the tension and evaluation information database according to the fourth embodiment. [Figure 11] FIG. 11 is a flowchart illustrating a procedure for evaluating the soundness of a cable according to the fifth embodiment. [Figure 12] FIG. 12 is a diagram showing temperature correction of tension according to the seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0031] [One embodiment] Figure 1A shows an example of a cable-stayed bridge including a health assessment system. The cable-stayed bridge shown in Figure 1A is an example, and the present disclosure is not limited to such cable-stayed bridges or their cables.

[0032] <Cable-stayed bridge 2> In the cable-stayed bridge 2 shown in Figure 1A, main towers 6 are erected on piers 4 to support girders 8, and multiple cables 10 are stretched between the piers 4 and girders 8. Each cable 10 forms a pair across the width of the girder 8 and is stretched at different angles with a gap between them along its length. Therefore, a considerable tension T acts on each cable 10 as it receives loads from the girders 8 and other components.

[0033] <Relationship between tension T of cable 10 and vibration> The vibration occurring in the cable 10 is closely related to the tension T, and more specifically, it is known that the vibration amplitude of the cable 10 depends on the tension T.

[0034] Therefore, the soundness evaluation system 12 of the present disclosure (hereinafter referred to as "evaluation system 12") irradiates radio waves Si to the cable 10, which is the target of evaluation of the tension T, receives reflected waves Sr from the cable 10, obtains vibration information of the cable 10 from the reflected waves Sr, and uses this vibration information to determine the tension T of the cable 10, thereby evaluating the soundness of the cable 10. To obtain the vibration information of the cable 10, it is possible to use the technology disclosed in Patent No. 6363209, "Interferometric Vibration Observation Device, Vibration Observation Program, Recording Medium, Vibration Observation Method, and Vibration Observation System," by the inventors of the present disclosure, for example.

[0035] <Vibration measurement using radio wave Si, incident angle of radio wave Si, vibration measurement position> When radio waves Si are applied to the cable 10, the radio waves Si are modulated by the vibration of the cable 10, and a reflected wave Sr containing vibration information is obtained from the cable 10. Therefore, to obtain vibration information from the cable 10, it is preferable to use radio waves Si with a wavelength smaller than the vibration amplitude of the cable 10, for example, millimeter waves.

[0036] The level of the reflected wave Sr is related to the angle of incidence of the radio wave Si with respect to the cable 10. Therefore, the closer the longitudinal direction of the cable 10 and the direction of irradiation of the radio wave Si are to a right angle, in other words, the smaller the angle of incidence of the radio wave Si with respect to the cable 10, the stronger the reflected wave Sr from the cable 10 is, and the higher the level of the reflected wave Sr becomes.

[0037] Since the evaluation system 12 acquires vibration information without contacting the evaluation target, it can be installed at a location away from the evaluation target. However, to improve the measurement accuracy of the vibration information of the cable 10, it is preferable to perform vibration measurement at a location that is not affected by the vibration of the evaluation target.

[0038] <Assessment target and arrangement of the evaluation system 12> FIG. 1B shows an example of the placement of the evaluation system 12 relative to the cable 10.

[0039] When the object to be evaluated is the cable 10 of the cable-stayed bridge 2, in order to improve the measurement accuracy of the vibration information, a location with less shaking is selected, for example, near the main tower 6. In this example, the vibration visualization radar unit 14 is installed near the main tower 6.

[0040] The cable 10 is provided with a pair of left and right cables 10-L and 10-R at the left and right positions, and radio waves Si are transmitted from the vibration visualization radar unit 14 toward each of the left cable 10-L and the right cable 10-R.

[0041] <Evaluation System 12> 2 shows an evaluation system 12, which is a soundness evaluation system according to one embodiment. The configuration shown in FIG. 2 is an example, and the present disclosure is not limited to such a configuration.

[0042] 2, the evaluation system 12 includes a vibration visualization radar unit 14, a temperature measurement unit 16, and a soundness evaluation unit 18. The vibration visualization radar unit 14 is connected to the soundness evaluation unit 18 via a data bus 19, and the temperature measurement unit 16 is connected to the soundness evaluation unit 18 via a data bus 21.

[0043] <Vibration Visualization Radar Section 14> The vibration visualization radar unit 14 is an example of a radar according to the present disclosure, and includes a radar unit 20, a radar control unit 22, a processing and analysis unit 24, and a radar information presentation unit 26.

[0044] The radar unit 20 includes a transmitter 28 and a receiver 30, and if the object to be evaluated is a cable-stayed bridge 2, it is installed near the main tower 6, which is less prone to swaying. The transmitter 28 includes a transmitting antenna (not shown), and transmits radio waves Si (e.g., millimeter waves) under the control of the radar control unit 22. The receiver 30 includes a receiving antenna, and receives reflected waves Sr from the cable 10.

[0045] Regarding the transmission of radio waves Si and reception of reflected waves Sr by the radar unit 20, the angle of incidence of the radio waves Si with respect to the cable 10 is adjusted to increase the level of the reflected waves Sr. When the radar unit 20 is aimed at the cable 10, the longitudinal direction of the cable 10 and the direction of radiation of the radio waves Si are generally set to be nearly perpendicular, that is, the angle of incidence of the radio waves Si with respect to the cable 10 is set to be small.

[0046] The radar control unit 22 is configured, for example, by a computer including a processor, a recording medium, etc., and generates the above-mentioned control signal, transmits radio waves Si from the transmitter 28, receives reflected waves Sr from the cable 10 at the receiver 30, takes in the received output, and outputs radar information including the transmitted signal and the received signal. Therefore, the radar control unit 22 performs information processing such as sending vibration information to the processing / analysis unit 24 and the radar information presentation unit 26 by controlling the radio wave transmission of the transmitter 28, controlling the reflected wave reception of the receiver 30, and obtaining the received signal from the receiver 30.

[0047] The processing and analysis unit 24 is configured, for example, by a computer including a processor, a recording medium, etc., and realizes functions such as signal processing, signal analysis, and power spectrum analysis by computer information processing. Such functions can be represented by a signal processing unit 32, a vibration information analysis unit 34, and a power spectrum analysis unit 36.

[0048] The signal processing unit 32 receives the signal received by the receiving unit 30 from the radar control unit 22, obtains vibration information from the received signal, and inputs the vibration information to a vibration information analysis unit .

[0049] The vibration information analysis unit 34 performs a graphing process on the vibration information received from the signal processing unit 32, and sends this output information to the power spectrum analysis unit 36 ​​and the radar information presentation unit 26. The graphing process of the vibration information performed by the vibration information analysis unit 34 is a process for obtaining image information in which, for example, time is plotted on the horizontal axis and vibration amplitude is plotted on the vertical axis.

[0050] The power spectrum analysis unit 36 ​​performs information processing such as performing a fast Fourier transform (FFT) on the vibration information to obtain power spectrum information representing the vibration information of the cable 10 contained in the reflected wave Sr, and provides this power spectrum information to the radar information presentation unit 26 and the soundness evaluation unit 18.

[0051] Then, under the control of the radar control unit 22, the radar information presentation unit 26 presents the received signal received from the radar control unit 22, the vibration information received from the vibration information analysis unit 34, and the power spectrum information received from the power spectrum analysis unit 36. This presented information allows the measurer to visually recognize the received signal representing the reflected wave Sr from the cable 10, the vibration information and power spectrum information of the cable 10.

[0052] In this vibration visualization radar unit 14, the processing and analysis unit 24 explicitly includes the signal processing unit 32, the vibration information analysis unit 34, and the power spectrum analysis unit 36 ​​as computer processor functions, but these functional units may also be configured as hardware.

[0053] <Temperature measurement unit 16> The temperature measurement unit 16 is an example of a temperature measurement means of the present disclosure. This temperature measurement unit 16 may be configured, for example, with an infrared sensor that simultaneously measures the temperature at multiple points on the cable 10 without contacting the cable 10, and acquires temperature information from the cable 10. This temperature information is provided to the health evaluation unit 18 in a timely manner.

[0054] <Soundness Assessment Department 18> The soundness evaluation unit 18 is configured, for example, by a computer, and includes an information input unit 38, a storage unit 40, a processing unit 42, an information output unit 44, and an information presentation unit 46, which are the basic components of a computer.

[0055] The information input unit 38 receives input of the cable ID, measurement date and time, cable attributes, design tension Tm of the cable 10, cable temperature ti, power spectrum information, evaluation criteria, evaluation results, etc. through a control function included in the processing unit 42. The cable temperature ti is acquired in a timely manner from the temperature measurement unit 16 connected to the information input unit 38.

[0056] The storage unit 40 is an example of a recording medium of the present disclosure. The storage unit 40 is composed of storage elements such as a read-only memory (ROM) and a random-access memory (RAM), and may also include an external storage device such as a hard disk. The ROM stores an operating system (OS), an evaluation processing program for the cable 10, an evaluation information database 48 (hereinafter referred to as "DB 48"), and the like. The RAM constitutes a work area for information processing. The DB 48 stores various information such as the cable ID, date and time, cable attributes, design tension Tm, cable temperature ti, natural vibration frequency fi (where i = order), tension T, measured tension Tr, difference ΔT, evaluation criteria, and evaluation results. The measured tension Tr is the tension T after temperature correction. The difference ΔT is the tension T or the pressure difference between the measured tension Tr and the design tension Tm.

[0057] The processing unit 42 mainly has a control function and a calculation function, and the control function includes control of information input, information recording, calculation, information output, information presentation, etc. for evaluating the soundness of the cable 10. The calculation function includes functions such as extracting the natural vibration frequency fi, calculating the tension T, temperature correcting the tension T (calculating the measured tension Tr), comparing the tension T with the design tension Tm, comparing the measured tension Tr with the design tension Tm, and evaluating the tension T or the measured tension Tr, by processing information. The latter function can be represented by a natural vibration frequency extraction unit 50, a tension calculation unit 52, a temperature correction unit 54, a comparison unit 56, and an evaluation unit 58.

[0058] The natural vibration frequency extraction unit 50 receives power spectrum information from the power spectrum analysis unit 36 ​​of the vibration visualization radar unit 14, and extracts the 1st, ..., and nth order natural vibration frequencies fi from this power spectrum information. The natural vibration frequencies fi are stored in the memory unit 40 under the control of the processing unit 42, and then stored in the DB 48.

[0059] The tension calculation unit 52 receives from the DB 48 the natural vibration frequency fi (Hz), the cable length L (m), the weight per unit length ρA (kg / m), and the bending rigidity (N·mm 2 ) is read The tension T of the cable 10 is calculated using a vibration equation, which will be described in detail later. The tension T obtained as a result of this calculation is stored in the memory unit 40 under the control of the processing unit 42, and is then stored in the DB 48.

[0060] The temperature correction unit 54 reads the cable temperature ti from the DB 48, and if this cable temperature ti differs from the reference temperature tm of the design tension Tm of the cable 10, performs temperature correction on the tension T or the design tension Tm. For example, if the tension T is corrected to the value at the reference temperature tm, the tension T after this temperature correction is the measured tension Tr.

[0061] The comparison unit 56 compares the tension T with the design tension Tm, or compares the measured tension Tr with the design tension Tm, calculates the difference ΔT between the tension T or the measured tension Tr and the design tension Tm, and stores this difference ΔT in the memory unit 40 and in the DB 48.

[0062] The evaluation unit 58 evaluates the difference ΔT obtained by the comparison unit 56 using the evaluation criteria read from the DB 48. This evaluation, for example, determines whether the difference ΔT is greater than a lower threshold LinL representing the evaluation criteria and equal to or less than an upper threshold LinU. If LinL≦ΔT≦LinU, the evaluation result of the soundness of the cable 10 is pass, and if LinL>ΔT or ΔT>LinU, the evaluation result is fail. This evaluation result is memorized in the memory unit 40 and stored in the DB 48.

[0063] The information output unit 44 reads out various information such as evaluation result information stored in the DB 48 of the storage unit 40 and outputs it to the information presentation unit 46 .

[0064] The information presenting unit 46 is configured, for example, by an LCD (Liquid Crystal Display) display device, and presents information such as the evaluation result information read from the storage unit 40. By presenting this information, the evaluation result of the soundness of the cable 10 can be recognized.

[0065] <db46> 3 shows an example of the DB 48. The DB 48 includes a plurality of evaluation information files 60-1, 60-2, . . . , 60-n (hereinafter simply referred to as "files 60") associated with cable IDs.

[0066] Each file 60 has a cable ID section 62, a date and time section 64, a cable attribute section 66, a design tension section 68, a cable temperature section 70, a natural vibration frequency section 72, an order section 74, a tension section 76, a measured tension section 78, a difference section 80, an evaluation criteria section 82, an evaluation result section 84, and a remarks section 86.

[0067] The cable ID section 62 stores ID information for identifying the cable 10 to be evaluated. This ID information includes identification information and address information of the cable 10.

[0068] The date and time section 64 stores date information, time information, etc., which indicate the date and time when the evaluation information was acquired.

[0069] The cable attribute section 66 stores information representing the cable attributes of the cable 10. In this example, the information required to calculate the tension T using the vibration acquired from the cable 10 includes bending stiffness, cable length, weight, etc. The cable attribute section 66 includes a bending stiffness section 66-1, a cable length section 66-2, and a weight section 66-3. The bending stiffness section 66-1 stores stiffness information of the cable 10, bending stiffness EI (N·mm 2 ) is stored. The cable length field 66-2 stores the length information of the cable 10 to be evaluated, ie, the cable length (m). The weight field 66-3 stores the weight information of the cable 10, ie, the weight per unit length of the cable 10 (kg / m).

[0070] The design tension section 68 stores tension information of the cable 10 at the time of design. The cable temperature section 70 stores temperature information of the cable 10 at the time of evaluation and temperature information acquired by the temperature measurement section 16.

[0071] The natural vibration frequency section 72 stores the natural vibration frequency fi extracted from the power spectrum information by the processing section 42 of the soundness evaluation section 18, where i is the order. The order section 74 stores order information indicating the order i of the natural vibration frequency fi.

[0072] The tension section 76 stores the tension T calculated by the tension calculation section 52. The measured tension section 78 stores the measured tension Tr (the tension corrected by the cable temperature ti).

[0073] The difference section 80 stores difference information indicating the difference ΔT between the tension T obtained by the comparison section 56 or the measured tension Tr and the design tension Tm.

[0074] The evaluation criteria section 82 stores evaluation criteria information acquired from the DB 48 under the control of the processing section 42 .

[0075] The evaluation result section 84 stores the evaluation result information obtained by the evaluation section 58. This evaluation result information stores pass or fail information as to the soundness of the cable 10 that is the evaluation target.

[0076] The remarks section 86 stores various information related to the evaluation conditions, such as information indicating the climate at the time of evaluation or measurement associated with the date and time information.

[0077] <Processing Procedure> 4 shows a procedure for evaluating the soundness of a cable, which is an example of a method or program for evaluating the soundness of a cable according to the present disclosure.

[0078] This processing procedure includes preparation for vibration measurement (S101), acquisition of temperature information (S102), recording of temperature information, design tension Tm, evaluation criteria information, and attribute information (S103), transmission of radio waves Si and reception of reflected waves Sr (S104), acquisition of vibration information (S105), signal processing (S106), graphing of vibration information (S107), presentation of vibration information (S108), calculation of power spectrum information (S109), presentation of power spectrum information (S110), extraction of natural vibration frequency fi (S111), recording of natural vibration frequency fi (S112), calculation of tension T (S113), temperature correction (calculation of measured tension Tr) (S114), calculation of difference information between tension T or measured tension Tr and design tension Tm (S115), evaluation of tension T or measured tension Tr (S116), presentation of evaluation results (S117), etc.

[0079] Preparation for vibration measurement (S101): In addition to the initial settings, at least the transmitter 28 and receiver 30 of the vibration visualization radar unit 14 are installed in a location with minimal shaking, and the antennas of the transmitter 28 and receiver 30 are installed facing the cable 10 to be measured.

[0080] Obtaining temperature information (S102): The temperature measurement unit 16 is used to measure the temperatures of the cables 10 and girders 8 that are the measurement targets, and the temperature information is input to the information input unit .

[0081] Recording of temperature information, design tension Tm, evaluation criteria information, and attribute information of cable 10 (S103): The aforementioned temperature information, design tension of cable 10 being measured, evaluation criteria information, and attribute information of cable 10 are obtained, input from information input unit 38, and stored and recorded in DB 48 in memory unit 40.

[0082] Transmission of radio waves Si and reception of reflected waves Sr (S104): Under the control of the radar control unit 22, radio waves Si are transmitted from the transmitter 28 toward the cable 10, and the reflected waves Sr from the cable 10 are received by the receiver 30. The receiver 30 obtains a reception signal representing the received reflected waves Sr.

[0083] Acquisition of vibration information (S105): The received signal obtained by the receiving unit 30 is acquired by the radar control unit 22, and this received signal is input from the radar control unit 22 to the processing and analysis unit 24.

[0084] Signal processing (S106): The received signal input to the processing / analysis unit 24 is received by the signal processing unit 32, which extracts vibration information of the cable 10 from the received signal and inputs this vibration information to the vibration information analysis unit 34.

[0085] Vibration information graphing process (S107): The vibration information analysis unit 34 performs graphing process on the vibration information received from the signal processing unit 32. This graphing process involves, for example, image processing in which the horizontal axis represents time and the vertical axis represents vibration amplitude, and this image signal is input to the radar information presentation unit 26 and the power spectrum analysis unit 36.

[0086] Presentation of vibration information (S108): The radar information presentation unit 26 acquires the graphed vibration information from the vibration information analysis unit 34, and presents this vibration information.

[0087] Calculation of power spectrum information (S109): The power spectrum analysis unit 36 ​​performs fast Fourier transform (FFT) processing on the vibration information to obtain power spectrum information from the vibration information. This power spectrum information is provided from the power spectrum analysis unit 36 ​​to the radar information presentation unit 26 and the soundness evaluation unit 18.

[0088] Presentation of power spectrum information (S110): The radar information presentation unit 26 presents, by graphical display, the power spectrum information received from the power spectrum analysis unit 36. The vibration visualization radar unit 14 performs the processes up to this point.

[0089] Extraction of natural vibration frequencies fi (S111): Processing shifts from the vibration visualization radar unit 14 to the soundness evaluation unit 18, where the natural vibration frequencies fi are extracted. The natural vibration frequency extraction unit 50 receives power spectrum information and determines the first through nth order natural vibration frequencies fi of the cable 10 from this power spectrum information.

[0090] Recording of natural vibration frequencies fi (S112): The first to n-th natural vibration frequencies fi of the cable 10 extracted by the natural vibration frequency extracting unit 50 are recorded in the memory unit 40 and stored in the DB 48.

[0091] Calculation of tension T (S113): The tension calculation unit 52 receives from the DB 48 the natural vibration frequency fi (Hz), the cable length L (m), the weight per unit length ρA (kg / m), the bending rigidity EI (N·mm 2 ), and calculate the tension T by substituting the order i into equation (1). The calculation results are stored in the storage unit 40 and in the DB 48.

[0092] Temperature correction (S114): When there is a temperature difference between the tension T calculated by the tension calculation unit 52 and the design tension Tm, temperature correction is required for either or both. The temperature correction unit 54 extracts the tension T calculated by the tension calculation unit 52 and the design tension Tm from the DB 48, and corrects the tension T (or the design tension Tm). The measured tension Tr is calculated by this temperature correction.

[0093] Calculation of difference information between tension T or measured tension Tr and design tension Tm (S115): The comparison unit 56 receives tension T or measured tension Tr and design tension Tm, and calculates the difference ΔT (= T - Tm) or the difference ΔT (= Tr - Tm) by comparing tension T with design tension Tm or comparing measured tension Tr with design tension Tm.

[0094] Evaluation of tension T or measured tension Tr (S116): The evaluation unit 58 reads out evaluation reference information from the DB 48, and compares this evaluation reference information with the difference ΔT to evaluate the tension T or measured tension Tr.

[0095] Presentation of evaluation result information (S117): The information presentation unit 46 receives the evaluation result information from the processing unit 42, presents this result information in association with the attribute information of the cable 10, and records it in the storage unit 40 and stores it in the DB 48.

[0096] <Calculation of tension T> The vibration equation shown in Equation 1 is used to calculate the tension T of the cable 10. This vibration equation is a relational expression that represents the bending vibration of a general cable.

[0097]

number

[0098]

number

[0099] Therefore, the tension calculation unit 52 of the processing unit 42 calculates the tension T by using Equation 2 and the natural vibration frequency fi, order i, bending rigidity EI, cable length L, and weight per unit ρA obtained from the DB 48.

[0100] <Effects of the embodiment> According to this embodiment, one of the following effects can be obtained. (1) According to the vibration visualization radar unit 14, radio waves Si are transmitted from the radar unit 20 toward the cable 10 and reflected waves Sr from the cable 10 are received, so that vibration information of the cable 10 can be obtained from the reflected waves Sr, and power spectrum information representing cable vibration can be obtained. In other words, vibration information that depends on the tension T of the cable 10 can be obtained without contacting the cable 10.

[0101] (2) According to the vibration visualization radar unit 14, the analysis output obtained by the vibration information analysis unit 34 and the power spectrum information obtained by the power spectrum analysis unit 36 ​​can be presented to the radar information presentation unit 26, and this information can be visualized and displayed. In other words, by visually checking the radar information presentation unit 26, the reception state of the radar unit 20 and the vibration state of the cable 10 can be easily recognized.

[0102] (3) The natural vibration frequency extraction unit 50 can extract the first to nth natural vibration frequencies fi of the cable 10 contained in the power spectrum information provided by the vibration visualization radar unit 14, and can detect the vibration information of the cable 10 at the natural vibration frequencies fi.

[0103] (4) The tension calculation unit 52 can accurately calculate the tension T of the cable 10 by computer-based information processing using a vibration equation that generally applies to cable vibrations.

[0104] (5) If there is a difference between the cable temperature during measurement and the reference temperature tm of the design tension Tm, the temperature correction unit 54 can correct the calculated tension T to the same temperature as the design tension Tm through temperature correction. This allows the measured tension Tr to be determined. Therefore, this temperature correction can improve the accuracy of the tension T and the evaluation accuracy of the actual measured tension Tr.

[0105] (6) The comparison unit 56 can compare the tension T or the measured tension Tr of the cable 10 with the design tension Tm to determine the difference ΔT between them. In this case, by comparing the measured tension Tr obtained by temperature correction with the design tension Tm, it is possible to eliminate temperature errors due to differences in the temperature of the design tension Tm.

[0106] (7) The evaluation unit 58 can evaluate whether the difference ΔT is within the allowable range defined in the evaluation criteria, and can evaluate whether the tension T or the measured tension Tr of the cable 10 is acceptable or unacceptable.

[0107] (8) According to the information presentation unit 46, the presentation information showing the evaluation results can be displayed on an LCD display unit or the like, and from the presentation information, it is possible to easily recognize whether the tension T or the measured tension Tr of the cable 10 is within the healthy range or abnormal.

[0108] (9) The memory unit 40 can store various information such as the evaluation date and time associated with the cable ID, cable attributes, design tension Tm, cable temperature ti, natural vibration frequency fi, tension T, tension T, measured tension Tr, and difference ΔT, and this information can be presented by the information presentation unit 46 under the control of the processing unit 42. In addition, this information can be stored in an external storage device under the control of the processing unit 42, and the evaluation process can be performed at a location other than the observation site.

[0109] (10) The vibration visualization radar unit 14 and the soundness evaluation unit 18 are connected by a data bus 19. If a wireless connection is used instead of the data bus 19, the soundness evaluation unit 18 can be operated at a location away from the vibration visualization radar unit 14 to extract the natural vibration frequency fi of the cable 10, calculate the tension T and the measured tension Tr, and perform evaluations and present the information. [Example]

[0110] 5 shows a processing procedure for evaluating the soundness of a cable 10 according to Example 1. This processing procedure shows an example of a cable soundness evaluation method or program according to the present disclosure. In FIG. 5, parts common to the processing procedure shown in FIG. 4 are denoted by the same reference numerals.

[0111] This processing procedure includes calculation of tension T (S201), temperature correction of tension T (S202), calculation of difference ΔT (S203), health evaluation (S204), generation of evaluation information (S205, S206), and information presentation (S207).

[0112] Calculation of tension T (S201): The tension T of the cable 10 is calculated using the relational expression (Equation 1). As described above, this calculation is performed by the tension calculation unit 52. The natural vibration frequency fi, bending rigidity EI, cable length L, and weight ρA are obtained from the DB 48, and the tension T can be calculated by applying these to the relational expression. This tension T is memorized in the memory unit 40 and stored in the DB 48.

[0113] Temperature correction of tension T (S202): The tension T calculated by the tension calculation unit 52 is the cable temperature ti at the time of acquiring the vibration information that served as the basis for the natural vibration frequency fi. Therefore, if this cable temperature ti differs from the reference temperature tm of the design tension Tm, temperature correction of the tension T is necessary. In this case, the tension T is corrected to the measured tension Tr with reference to the cable temperature ti. This measured tension Tr is stored in the memory unit 40 together with the tension T, and then stored in the DB 48.

[0114] Calculation of difference ΔT (S203): The tension T is compared with the design tension Tm, and the difference ΔT (= T - Tm) between them is calculated, or the measured tension Tr is compared with the design tension Tm, and the difference ΔT (= Tr - Tm) between them is calculated. These differences ΔT are stored in the memory unit 40 and in the DB 48.

[0115] Soundness evaluation (S204): For this detection evaluation, evaluation criteria information is read from DB 48, and the difference ΔT is compared with this evaluation criteria to evaluate the tension T or the measured tension Tr. The evaluation criteria represent the allowable range of the difference ΔT. Therefore, if LinL≦ΔT≦LinU, the evaluation of the difference ΔT is pass, and if LinL>ΔT or ΔT>LinU, the evaluation of the difference ΔT is fail.

[0116] Generation of evaluation information (S205, S206): If the evaluation result is pass, the processing unit 42 generates evaluation information indicating pass (S205), and if the evaluation result is fail, the processing unit 42 generates evaluation information indicating fail (S206). This evaluation result information is stored in the storage unit 40 and stored in the DB 48.

[0117] Information presentation (S207): The processing unit 42 presents various pieces of information stored in the DB 48, allowing the evaluation results of the cable 10 to be visually confirmed.

[0118] <Effects of Example 1> According to the first embodiment, one of the following effects can be obtained.

[0119] (1) Calculation of tension T using vibration information provided by the vibration visualization radar unit 14, calculation of the measured tension Tr by temperature correction of tension T, calculation of the difference ΔT between tension T or the measured tension Tr and the design tension Tm, and comparison of this difference ΔT with the evaluation standard to evaluate the soundness of the cable 10 and present the evaluation information.

[0120] (2) The evaluation information can be presented by determining whether the soundness is pass or fail depending on whether the difference ΔT is within a reference range, and the soundness of the cable 10 being measured can be easily recognized. [Example]

[0121] The second embodiment is an example of processing by the vibration information analysis unit 34 and the power spectrum analysis unit 36 ​​in the processing and analysis unit 24 shown in FIG.

[0122] FIG. 6 shows a graph of vibration information according to Example 2, with the horizontal axis representing measurement time (sec) and the vertical axis representing displacement (mm) to show the transition of the displacement. As described above, the vibration information analysis unit 34 (FIG. 2) receives vibration information from the signal processing unit 32 and performs a graphing process on this vibration information. The graphed vibration information is provided to the radar information presentation unit 26 and presented as visualized information. The magnitude and transition of vibration can be visually confirmed from this visualized information.

[0123] FIG. 7 shows power spectrum information and the first through nth natural vibration frequencies according to the second embodiment, with frequency (Hz) on the horizontal axis and power on the vertical axis, illustrating the power transition and the natural vibration frequencies. As described above, the power spectrum analysis unit 36 ​​(FIG. 2) receives the output information from the vibration information analysis unit 34 and performs arithmetic processing on the vibration information using a fast Fourier transform (FFT), such as a discrete Fourier transform. The analysis result information from the power spectrum analysis unit 36 ​​is provided to the radar information presentation unit 26 and presented as visualized information. The power transition and the natural vibration frequencies can be visually confirmed from this visualized information. The radar information presentation unit 26 may present the analysis results by presenting the first through nth natural vibration frequency orders as power spectrum information.

[0124] The displacement shown on the vertical axis in Fig. 6 is x(n), and the power shown on the vertical axis in Fig. 7 is |X(k)| 2 Then, the power spectrum obtained by the calculation using the discrete Fourier transform can be expressed by the following equation 3.

number

[0125] <Effects of Example 2> According to the second embodiment, one of the following effects can be obtained.

[0126] (1) Vibration information can be acquired and stored without contacting the cable 10, and can be visually confirmed by presenting it on the radar information presenting unit 26, allowing the transition of the information to be confirmed.

[0127] (2) The radar information presentation unit 26 can present information from the vibration visualization radar unit 14, and can present this information together with vibration information and power spectrum information, allowing these pieces of information to be easily compared.

[0128] (3) The power spectrum information can also clearly indicate the order of the first to fifth natural vibration frequencies, making it easy to check the acquisition status of several natural vibration frequencies and improving measurement accuracy. [Example]

[0129] 8 shows a processing procedure for calculating the measured tension Tr by temperature correction of the tension T according to the third embodiment. This processing procedure is an example of a temperature correction method according to the present disclosure using the vibration method. This temperature correction is the same whether the vibration method or the higher-order vibration method is used.

[0130] The temperature correction processing procedure includes calculating tension T1 from the primary natural vibration frequency f1 (S301), calculating tension T2 from the secondary natural vibration frequency f2 (S302), calculating tension T (S303), calculating corrected tension Tt (S304), and calculating measured tension Tr (S305).

[0131] Calculation of tension T1 from first natural vibration frequency f1 (S301): To calculate this tension T1, the first natural vibration frequency f1 obtained by the natural vibration frequency extraction unit 50 (FIG. 2) and Equation 4 are used.

number

[0132] Calculation of tension T2 from second-order natural vibration frequency f2 (S302): To calculate this tension T2, the second-order natural vibration frequency f2 obtained by the natural vibration frequency extraction unit 50 (FIG. 2) and Equation 5 are used.

number

[0133] Calculation of tension T (S303): The tension T is calculated from the average value of tensions T1 and T2. Equation 6 is used to calculate this tension T. T=(T1+T2) / 2 (Formula 6)

[0134] Calculation of corrected tension Tt (S304): This corrected tension Tt is corrected count information of tension T according to temperature, and can be calculated using Equation 7. Tt=A×(CB) / 15×2 (Formula 7) In Equation 7, A: Corrected tension at ±15°C B: Measured main girder temperature C: Measured cable temperature

[0135] The data A, B, and C are given externally, and in Equation 7, the division by 2 is used to calculate the correction tension Tt per cable 10 when the cable 10 is configured as a pair of cables, as shown in Figure 1B.

[0136] Calculation of measured tension Tr (S305): If the tension T corrected by temperature is the measured tension Tr, this measured tension Tr can be calculated from the tension T and the corrected tension Tt using Equation 8. Tr=T+Tt (Formula 8)

[0137] 9 shows an example of a correction tension table 90. This correction tension table 90 has a cable number section 92, an attribute section 94, a correction tension section 96, and the like. The cable number section 92 stores cable numbers S-1, S-2, ..., S-18 as identification information for specifying the cables. The attribute section 94 stores attribute information such as the cable diameter of each cable 10. The correction tension section 96 stores a correction tension A at ±15°C.

[0138] In this example, a value representing the corrected tension A at ±15°C is obtained for each cable. If cable 10 is made up of 18 pairs of cables numbered S-1, S-2, ..., S-18, the corrected tension A at ±15°C can be obtained for each of cable numbers S-1, S-2, ..., S-18.

[0139] <Effects of Example 3> According to the third embodiment, one of the following effects can be obtained.

[0140] (1) The tension T can be calculated by averaging the tension T1 calculated from the primary natural vibration frequency f1 and the tension T2 calculated from the secondary natural vibration frequency f2.

[0141] (2) If the corrected tension Tt is calculated using the corrected tension A at a temperature of ±15°C to reflect the influence of external temperature, the measured main girder temperature B, and the measured cable temperature C, the corrected tension Tt and the tension T can be used to calculate the measured tension Tr, and this measured tension Tr can be used to evaluate the integrity of the cable 10. [Example]

[0142] 10 shows an example of a tension and evaluation information database (DB) 98 according to Example 4. The tension and evaluation information is ultimately stored in DB 90 and presented.

[0143] The DB 98 includes a measurement point number section 100, a natural vibration frequency section 102, a tension section 104, and a determination result section 106.

[0144] The measurement point number section 100 stores identification information such as location information of the cable 10 and a number for specifying the measurement point. In this example, the measurement point number indicates the number (n) of cables 10 that have been measured.

[0145] The natural vibration frequency section 102 stores, for example, the first to fifth natural vibration frequencies fi.

[0146] The tension unit 104 is configured with a vibration method unit 104-1 and a high-order vibration method unit 104-2, and in either case, information indicating the tension corresponding to the presence or absence of temperature correction is stored. In other words, the tension unit 104 stores the tension calculated from the natural vibration frequency, etc.

[0147] In this case, there are two types of tension calculations: the vibration method and the high-order vibration method, and the calculated tension for each method is stored depending on whether or not temperature correction is performed. In this case, the operator simply selects the tension calculation method (vibration method, high-order vibration method) and whether or not temperature correction is performed. As a result, the numerical value of the tension calculation result is stored in the appropriate field.

[0148] Information indicating the result of the judgment, normal or abnormal, is stored in the judgment result section 106. The judgment of normal or abnormal is made based on predetermined judgment criteria, such as normal if the "tension value of the measurement result" is within ±0% of the "design calculation value," and abnormal if it exceeds or falls below that, and the result is stored and displayed in the corresponding column.

[0149] <Effects of Example 4> According to the fourth embodiment, one of the following effects can be obtained. (1) The relationship between the natural vibration frequency, tension, and soundness evaluation results identified by the measurement point number is clearly indicated, allowing the soundness of the cable 10 to be visually confirmed.

[0150] (2) It is possible to check whether the calculated tension was corrected for temperature or whether the vibration method or the high-order vibration method was used, and the transition of the evaluation results can be easily confirmed. [Example]

[0151] 11 shows a processing procedure for evaluating the soundness of the cable 10 according to Example 5. This processing procedure is an example of the method or program for evaluating the soundness of a cable according to the present disclosure.

[0152] This processing procedure includes a process of comparing and verifying the measured tension Tr obtained by the soundness evaluation method of the present disclosure with the tension Tq obtained by a method other than the soundness evaluation method of the present disclosure (hereinafter referred to as the "conventional method"). This processing procedure includes measuring the vibration frequency and calculating the tension Tq by the conventional method (S401), processing by the vibration visualization radar unit 14 by the method of the present disclosure (S402), extracting the natural vibration frequency fi and calculating the measured tension Tr (S403), verifying the measured tension Tr (S404), and evaluating the soundness (S405).

[0153] Measuring frequency by conventional method and calculating measured tension Tr (S401): The frequency of the cable 10 is measured by a conventional method other than the soundness evaluation method of the present disclosure, and the tension Tq of the cable 10 is calculated using this frequency.

[0154] Processing by the vibration visualization radar unit 14 (S402): The vibration visualization radar unit 14 of the present disclosure acquires cable vibration information and calculates power spectrum information. The details of this process have been described above, so they will not be repeated here.

[0155] Extraction of natural vibration frequency fi and calculation of measured tension Tr (S403): The soundness evaluation unit 18 of the present disclosure extracts the natural vibration frequency fi and calculates the measured tension Tr of the cable 10. The details of this process have been described above, so they will not be repeated here.

[0156] Verification of measured tension Tr (S404): The measured tension Tr is compared with the tension Tq obtained by the conventional method to verify the measured tension Tr. If the result of this verification shows that the measured tension Tr is the same as or close to the tension Tq, this measured tension Tr is adopted.

[0157] Health evaluation (S405): The health evaluation unit 18 of the present disclosure compares the design tension Tm with the measured tension Tr, calculates the difference ΔT between the two, and determines whether this difference ΔT is within the range of the evaluation criteria to evaluate the health of the cable 10. Details of this process have been described above, so further details will be omitted.

[0158] <Effects of Example 5> According to the fifth embodiment, one of the following effects can be obtained.

[0159] (1) The tension Tq of the cable 10 can be measured using the conventional method, and the actual tension Tr of the cable 10 can be measured using the soundness evaluation system, and the equivalence and reliability of the actual tension Tr and the tension Tq can be verified. If, as a result of this verification, the actual tension Tr is the same as or close to the tension Tq obtained by the conventional forward method, the actual tension Tr can be evaluated as a true value. The soundness of the cable 10 can be evaluated using this actual tension Tr, allowing for a more accurate evaluation.

[0160] (2) The actual tension Tr can be calculated using the tension T.

[0161] (3) By comparing the measured tension Tr with the design tension Tm, if the two are equal or close to each other, the soundness of the cable 10 can be evaluated based on the comparison result, allowing for a more accurate evaluation. [Example]

[0162] The soundness assessment system 12 shown in FIG. 1 may be configured as a soundness assessment device for the cable 10 by mounting the vibration visualization radar unit 14 and the soundness assessment unit 18 in a single housing, for example.

[0163] <Effects of Example 6> According to the sixth embodiment, one of the following effects can be obtained. (1) The soundness evaluation device can be moved and set up on the cable-stayed bridge to be measured, and the necessary measurements and evaluation results can be displayed on the soundness evaluation device.

[0164] (2) By providing this soundness evaluation device with a communication function, it is possible to perform control and tension calculations on the management center side through a communication connection with the management center.

[0165] (3) According to this soundness evaluation device, if the radar information presentation unit 26 on the vibration visualization radar unit 14 side and the information presentation unit 46 on the soundness evaluation unit 18 side are configured as a common device, for example, an LCD display, it is possible to selectively or simultaneously present radar information or soundness evaluation information by switching functions. [Example]

[0166] FIG. 12 shows an example of temperature correction of tension T using a temperature-corrected tension curve (standard curve) according to Example 7.

[0167] Figure 12 shows a temperature-corrected tension curve M(t) that represents the relationship between temperature t and tension T, with temperature t on the horizontal axis and tension on the vertical axis. This temperature-corrected tension curve M(t) can be obtained by measuring the relationship between tension T (or design tension Tm) and cable temperature in advance and storing this temperature-corrected tension curve data in DB48.

[0168] When tension T is calculated using the vibration information described above, if the cable temperature associated with tension T is ti and this cable temperature ti differs from the reference temperature tm, tension T can be corrected to the measured tension Tr corresponding to the reference temperature tm using the temperature correction tension curve M(t). This measured tension Tr can then be used for comparison with the design tension Tm.

[0169] <Effects of Example 7> According to the seventh embodiment, one of the following effects can be obtained. (1) The temperature of the measured tension Tr and the design tension Tm can be made the same, and the temperature difference ΔT between the two can be removed, eliminating the temperature error.

[0170] (2) The influence of temperature can be avoided, and the accuracy of the soundness evaluation of the cable 10 can be improved.

[0171] In this Example 7, the tension T is corrected to the measured tension Tr. However, it is also possible to calculate the corrected design tension Tmx at the cable temperature ti at the time of measurement using the design tension Tm at the reference temperature tm using a similar temperature-corrected tension curve M(t), and use this corrected design tension Tmx for comparison with the tension T.

[0172] Other Embodiments (1) In the above embodiment, the vibration visualization radar unit 14 having a vibration visualization function is exemplified as the radar of the present disclosure. However, a radar having only the function of acquiring power spectrum information from the vibration information obtained from the radar unit 20, that is, a radar not having a vibration visualization function, may be used instead of the vibration visualization radar unit 14.

[0173] (2) Instead of temperature correction of the tension T or the design tension Tm, a process may be performed in which a design tension Tmn that matches the current temperature is selected from a plurality of design tensions Tmn corresponding to a plurality of reference temperatures and compared with the tension T.

[0174] (3) In the above embodiment or example, the tension difference ΔT between the tension T or the measured tension Tr and the design tension Tm is calculated using both, but either one of them may be used.

[0175] (4) In the above embodiments and examples, both the tension T and the measured tension Tr are used to evaluate the soundness of the cable, but if temperature correction of the tension T is not essential and the effect of temperature can be ignored, the tension T may be the measured tension Tr. In other words, either the tension T or the measured tension Tr (tension T after temperature correction) may be used to evaluate the tension T.

[0176] (5) Although the cable-stayed bridge 2 is given as an example of the object of evaluation of the cable 10, it can also be used for bridges other than cable-stayed bridges, and the tension of the stretched cable 10 can be determined and its soundness can be evaluated.

[0177] (6) In the soundness evaluation system 12 shown in FIG. 2, the radar information presentation unit 26 and the information presentation unit 46 may be integrated and desired information may be presented by switching the function.

[0178] (7) Although weight per unit length is used for cable attributes, mass per unit length may also be used. [Industrial Applicability]

[0179] As described above, according to the present disclosure, the tension of a tensioned cable, such as a cable-stayed bridge, can be measured without contact with the cable to determine the actual tension, and the soundness of the cable can be evaluated by comparing this actual tension with the design tension, and the evaluation results can be presented. [Explanation of symbols]

[0180] 2 Cable-stayed bridge 4. Piers 6 Main tower 8 digits 10 Cable 10-L Left Cable 10-R Right Cable 12. Soundness Assessment System 14 Vibration visualization radar unit 16 Temperature measurement section 18. Soundness Assessment Department 19 Data Bus 20 Radar section 21 Data Bus 22 Radar control unit 24 Processing and Analysis Section 26 Radar information presentation unit 28 Transmitter 30 Receiving unit 32 Signal Processing Section 34 Vibration information analysis department 36 Power spectrum analysis section 38 Information input section 40 Storage section 42 Processing section 44 Information output section 46 Information Presentation Department 48 Evaluation Information Database 50 Natural vibration frequency extraction unit 52 Tension calculation section 54 Temperature correction section 56 Comparison section 58 Evaluation Department 60-1, 60-2, 60-n files 62 Cable ID section 64 Date and time section 66 Cable Attributes 66-1 Bending stiffness section 66-2 Cable length 66-3 Parts by weight 68 Design tension section 70 Cable temperature section 72 Natural vibration frequency section 74 Order part 76, 104 tension section 78 Actual tension measurement section 80 Difference part 82 Evaluation Criteria Section 84 Evaluation Results Section 86 Remarks section 90 Correction Tension Table 92 Cable number section 94 Attribute section 96 Correction tension section 98 Tension and Evaluation Information Database 100 Measurement point number section 102 Natural vibration frequency section 106 Judgment result section

Claims

1. A system for assessing the health of an installed cable, comprising: a radar that transmits radio waves toward the cable, receives reflected waves from the cable, and acquires power spectrum information from the reflected waves; a soundness evaluation unit that calculates a tension of the cable using the natural vibration frequency extracted from the power spectrum information and compares the calculated tension with a design tension to evaluate the soundness of the cable; A cable health assessment system, including:

2. 2. The cable health evaluation system of claim 1, further comprising a temperature measurement unit that measures the temperature of the cable, wherein the health evaluation unit corrects the tension or the design tension based on the temperature information of the cable and evaluates the health of the cable using the corrected tension or the design tension.

3. 3. The cable health evaluation system according to claim 1, wherein the health evaluation unit compares the tension with the design tension to determine a difference between the tension and the design tension, and evaluates the health of the cable based on whether the difference is within a reference range.

4. The radar is installed in a place with little shaking and transmits the radio waves and receives the reflected waves, the soundness evaluation unit calculates the tension using the natural vibration frequency acquired according to a swaying state of the cable.

3. The cable health evaluation system according to claim 1 or 2.

5. The soundness evaluation unit calculates the soundness by the following relational expression (Equation 1): [Equation 1] The cable health evaluation system according to claim 1 or 2, further comprising: calculating the tension.

6. A method for evaluating the health of an installed cable, comprising: a step of transmitting radio waves toward the cable by a radar and acquiring power spectrum information from the reflected waves received from the cable; a soundness evaluation unit calculating a tension of the cable using the natural vibration frequency extracted from the power spectrum information, and comparing the calculated tension with a design tension to evaluate the soundness of the cable; A cable health assessment method, including:

7. Further, a step of measuring the temperature of the cable by a temperature measurement unit; a step in which the health evaluation unit corrects the tension or the design tension using temperature information acquired from the temperature measurement unit, and evaluates the health of the cable using the corrected tension or the design tension; The cable health evaluation method according to claim 6, comprising:

8. 8. The cable health evaluation method according to claim 6, further comprising a step in which the health evaluation unit compares the tension with the design tension to determine a difference between the tension and the design tension, and evaluates the health based on whether or not this difference is within a reference range.

9. Furthermore, the radar transmits radio waves in a location with little shaking and acquires the reflected waves from the cable; a step in which the soundness evaluation unit calculates the tension using the natural vibration frequency acquired according to a swaying state of the cable; The cable health evaluation method according to claim 6 or 7, comprising:

10. The soundness evaluation unit calculates the soundness by the following relational expression (Equation 1): [Equation 2] The cable health evaluation method according to claim 6 or 7, further comprising the step of calculating the tension.

11. A method for evaluating the health of an installed cable, comprising: a step of transmitting radio waves toward the cable, receiving reflected waves from the cable, acquiring power spectrum information from the reflected waves, and obtaining the natural vibration frequency of the cable using a radar, and obtaining the tension of the cable using the natural vibration frequency; acquiring vibration information from the cable without using the radar, and acquiring tension of the cable using the vibration information; verifying the tension obtained using the radar by comparing it with the tension obtained without using the radar; a step of comparing the tension acquired using the radar with a design tension to evaluate the soundness of the cable; A cable health assessment method, including:

12. On the computer, a function of transmitting radio waves from a radar toward a cable and acquiring power spectrum information from the reflected waves received from the cable by the radar; a function of extracting a natural vibration frequency from the power spectrum information by a natural vibration frequency extraction unit; a function of calculating the tension of the cable by a tension calculation unit using the natural vibration frequency; a function of evaluating the soundness of the cable by a soundness evaluation unit by comparing the tension with a design tension; A program to execute.

13. Furthermore, the computer a function of acquiring temperature information of the cable; a function of correcting the tension or the design tension using the temperature information; a function of evaluating the soundness of the cable using the corrected tension or the design tension; The program according to claim 12, which causes the program to execute the following.

14. Furthermore, the computer The program according to claim 12 or 13, which executes a function of comparing the tension with the design tension to determine a difference between the tension and the design tension, and evaluating the soundness of the cable based on whether or not the difference is within a reference range.

15. Furthermore, the computer a function of transmitting the radio waves to a radar installed in a location with little shaking and acquiring the reflected waves from the cable; a function of causing the tension calculation unit to calculate the tension using the natural vibration frequency acquired according to the swaying state of the cable; The program according to claim 12 or 13, which causes the program to execute the above.

16. Furthermore, the computer is configured to calculate the following relation (Equation 1): [Equation 3] The program according to claim 12 or 13, further comprising a function for calculating the tension.

17. A recording medium storing the program according to claim 12 or 13.

18. A recording medium storing the program according to claim 14.

19. A recording medium storing the program according to claim 15.

20. A recording medium storing the program according to claim 16.

21. An apparatus for evaluating the health of an installed cable, comprising: a radar that transmits radio waves toward the cable and receives reflected waves from the cable to acquire power spectrum information; a soundness evaluation unit that extracts a natural vibration frequency from the power spectrum information, calculates a tension of the cable using the natural vibration frequency, and compares the calculated tension with a design tension to evaluate the soundness of the cable; an information presentation unit that presents evaluation information that represents the evaluation result of the soundness; A cable health assessment device comprising:

Images