A building structure cable force measuring method, system and device

Abstract

The application provides a method, system and device for measuring the cable force of an existing cable of a building structure, and relates to the technical field of building cable structure monitoring. The method mainly comprises the following steps: installing an auxiliary cable clamp on the existing cable; installing a vibration frequency acquisition device; setting an auxiliary cable and adjusting the sum of the cable forces of the auxiliary cable to a preset cable force; obtaining the natural frequencies of two orders of the existing cable; selecting a solving equation set between the measured cable force of the existing cable and the natural frequencies thereof; estimating an initial value of the bending stiffness of the existing cable; selecting corresponding equations from the solving equation sets of the two orders respectively, substituting the natural frequencies of the two orders into the two equations for simultaneous solving to obtain a current value of the measured cable force of the existing cable; performing a result conformity judgment after the bending stiffness of the existing cable is calculated; and calculating the cable force of the existing cable based on the current value of the measured cable force of the existing cable and the preset cable force. The scheme can conveniently, quickly and accurately calculate the cable force and other parameters of the existing cable.

Description

Technical Field

[0001] This invention relates to the field of building cable structure monitoring technology, and in particular to a method, system and device for measuring the cable force of existing building cables. Background Technology

[0002] In tensioned and cable-stayed structures, cables are key components providing structural stiffness and load-bearing capacity. Cable forces directly affect structural performance. During the structure's service life, it is necessary to periodically monitor cable forces to assess changes in cable performance and the overall structural performance.

[0003] Currently, the main methods for measuring cable force include: direct measurement, pressure gauge method, frequency method, and magnetic flux method. Among these, the pressure gauge method is only applicable during the tensioning phase of construction; after the tensioning equipment is removed at the end of construction, cable force cannot be measured again, making it unsuitable for long-term monitoring. The direct measurement method typically measures the surface strain of the cable, but the measuring equipment is complex and can only measure the change in cable force, not the absolute value. The magnetic flux method calculates cable force by measuring the change in magnetic flux corresponding to the change in the cable's cross-section under varying force. However, the magnetic flux method requires prior calibration on cables of the same type, resulting in high costs for measuring equipment and preparation.

[0004] In comparison, the frequency method is less expensive, requires less on-site measurement work, and can directly obtain the absolute value of cable force, making it a widely used method. However, the frequency method is not accurate for measuring shorter, thicker cables in building structures. This is because shorter cables are significantly affected by their own bending stiffness and boundary conditions. Semi-parallel wire bundles and stranded cables commonly used in building structures are formed by twisting steel wires. Their bending stiffness is affected by various factors such as the internal structure of the cable, the twisting method between the wires, and the magnitude of friction between the wires. The bending stiffness directly obtained from the cable's cross-sectional shape often has a large error and needs to be obtained experimentally. However, in conventional tests, the bending stiffness of the cable itself is also difficult to accurately determine. Because the constraint of the cable clamp on the cable in a building structure is between hinged and rigid, it is difficult to determine its specific constraint conditions. Therefore, directly using the frequency method to measure cable force in building structures remains quite challenging. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, and device for measuring the cable tension of existing cables in building structures, so as to solve at least one of the aforementioned technical problems in the prior art.

[0006] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a method for measuring the cable tension of existing cables in a building structure, comprising the following steps: Step 1: Install a pair of auxiliary cable clamps between the cable clamps at both ends of the existing cable; install a vibration frequency acquisition device on the existing cable between the two auxiliary cable clamps; symmetrically set auxiliary cables between the two auxiliary cable clamps and adjust the cable force of the auxiliary cables to the preset cable force. ; Step 2: Tap the existing cable and use a vibration frequency acquisition device to obtain the first and third natural frequencies of the existing cable. Based on two orders, a set of equations relating the axial force of the beam fixed at both ends to its natural frequency is selected from the frequency method theory formula, and used as the basis for measuring the cable force of the existing cable. Its natural frequency Solve the system of equations between the given equations, including the first parameter. and the second parameter : First parameter The specific formula can be: ; in, This indicates the bending stiffness of the existing cables; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula can be: ; Step 3: Estimate the initial value of the bending stiffness of the existing cables based on the structural parameters and bending stiffness theoretical formulas. Based on the existing initial value of the bending stiffness of the cable And the second parameter lookup table, to determine the initial value of the second parameter. The initial range; Step 4: Based on the initial value of the second parameter From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter ; Step 5: Based on the first parameter C and its formula, calculate the bending stiffness of the existing cable. Then, the current value of the cable force is measured using the existing cables. and the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter If the initial range is determined, then proceed to step 6; if the second parameter... Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Proceed to step 3; Step 6: Measure the current cable force based on the existing cables. and preset cable force Calculate the existing cable force The specific formula can be: .

[0007] By adding auxiliary cables and cable clamps, calculation conditions can be created that satisfy the equations relating the axial force of the beam fixed at both ends to its natural frequency. Then, the existing cable force and bending stiffness can be obtained by solving the relevant equations in the frequency method.

[0008] In one feasible implementation, the cable force is preset in step 1. It is an integer value not exceeding 10% of the design cable force.

[0009] In one feasible implementation, step 1 further includes installing a surface strain acquisition device on the existing cable between the two auxiliary cable clamps, and adjusting the cable force of the auxiliary cable to a preset cable force. Then, the strain change value of the existing cable was obtained through a surface strain acquisition device. This allows for the simultaneous acquisition of strain changes in the existing cables under the action of the auxiliary cables.

[0010] In one feasible implementation, the method further includes step 7, based on the existing cable force. and the strain change value of the existing cables Calculate the axial stiffness of the existing cables The specific formula can be: .

[0011] In one feasible implementation, when the first-order natural frequency of the existing cable is obtained in step 2... and the third natural frequency At that time, the cable force was measured using existing cables. Its natural frequency The systems of equations to be solved are as follows: ; .

[0012] Secondly, based on the same inventive concept, this application also provides a system for measuring the tension of existing cables in building structures, including a data receiving module, a data processing module, and a result generation module; The data receiving module is used to receive the preset cable force. The first and third natural frequencies of the existing cables Initial value of existing cable bending stiffness and the initial value of the second parameter ; The data processing module includes an equation unit, an iterative calculation unit, and a solution unit: The equation unit stores existing cable force measurements. Its natural frequencies of various orders Solving the system of equations and the first parameter The formula, the second parameter Formulas and existing cable forces The formula; First parameter The specific formula can be: ; in, This indicates the bending stiffness of the existing cables; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula can be: ; Existing cable force The specific formula can be: ; The iterative calculation unit is based on the existing first and third order natural frequencies of the cable. Select the appropriate system of equations to solve; based on the initial value of the second parameter. From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter Based on the first parameter The formula was then retrieved to calculate the bending stiffness of the existing cable. Then, the current value of the cable force is measured using the existing cables. And retrieve the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter The initial range will be the current value of the existing cable force measurement. Send to the solver; if the second parameter Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Iterative calculation until the second parameter is obtained. Falling into the initial value of the second parameter The initial range; The solution unit measures the current value of the cable force based on the existing cable. and preset cable force Retrieve the existing cable force calculation formula and calculate the existing cable force. ; The result generation module is used to generate the existing cable force. and existing cable bending stiffness Outsourced.

[0013] In one feasible implementation, the data receiving module is further configured to receive the strain change values ​​of the existing cables. The equation unit also stores existing cable axial stiffness formulas. The solution unit is also based on the existing cable force. and the strain change value of the existing cables The axial stiffness of the existing cable is calculated using the existing cable axial stiffness formula. The result generation module is also used to generate the existing cable axial stiffness. Outsourced.

[0014] Thirdly, based on the same inventive concept, this application also provides a device for measuring the tension of existing cables in a building structure, including a processor, a memory, and a bus. The memory stores instructions and data read by the processor, and the processor is used to call the instructions and data in the memory to execute the method for measuring the tension of existing cables in a building structure as described above. The bus connects the functional components to transmit information.

[0015] By adopting the above technical solution, the present invention has the following beneficial effects: This invention provides a method, system, and device for measuring the cable force of existing cables in building structures. By setting auxiliary cables and auxiliary clamps on existing cables, and after tensioning the auxiliary cables, the constraint of the auxiliary clamps on the existing cables achieves a fixed connection effect. Thus, the cable force and bending stiffness of the existing cables can be calculated quickly, accurately, and conveniently using relevant formulas for beams with fixed connections at both ends. At the same time, by measuring the strain change of the existing cables during the tensioning process of the auxiliary cables, the axial stiffness of the existing cables can also be calculated. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating a method for measuring the tension of existing cables in a building structure, as provided in an embodiment of the present invention; Figure 2 A system diagram of a method for measuring the tension of existing cables in a building structure, provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the arrangement of an existing cable tension measuring device for a building structure, provided as an embodiment of the present invention. Figure 4 for Figure 3 Enlarged illustration of the front half of the auxiliary cable clamp; Figure 5 This is an example diagram illustrating the mode shape and frequency simulation of the steel wire under two-end fixed constraint according to an embodiment of the present invention. Figure 6 This is an example diagram of the acquisition of the mode shape and frequency of the steel wire under the constraint of an existing cable force measuring device in a building structure, as provided in an embodiment of the present invention.

[0018] Figure label: 1-Existing cable; 2-Auxiliary cable clamp; 21-First groove; 22-Second groove; 23-Mounting hole; 3-Auxiliary cable; 4-Vibration sensor; 5-Strain sensor. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] To facilitate understanding of the embodiments of this application, the inventive concept of this application is briefly described as follows: To address the technical problems mentioned in the background section, this application proposes installing auxiliary cable clamps and auxiliary cables on existing cables. After tensioning the auxiliary cables, the constraint of the auxiliary cable clamps on the existing cables achieves a fixed connection effect. This allows the application of relevant formulas for beams with fixed ends in the frequency method to construct a system of simultaneous equations and solve for the cable force and bending stiffness of the existing cables. Simultaneously, by measuring the strain change of the existing cables during the tensioning process of the auxiliary cables, the axial stiffness of the existing cables can also be calculated.

[0023] The present invention will be further explained below with reference to specific embodiments.

[0024] It should also be noted that the specific embodiments or implementation methods described below are a series of optimized settings listed by the present invention to further explain the specific content of the invention, and these settings can be combined or used in conjunction with each other.

[0025] Example 1: like Figure 1 As shown in the figure, this embodiment provides a method for measuring the cable tension of existing cables in a building structure, including the following steps: Step 1: Install a pair of auxiliary cable clamps between the cable clamps at both ends of the existing cable; install a vibration frequency acquisition device on the existing cable between the two auxiliary cable clamps; symmetrically set auxiliary cables between the two auxiliary cable clamps and adjust the cable force of the auxiliary cables to the preset cable force. ; Step 2: Tap the existing cable and use a vibration frequency acquisition device to obtain the first and third natural frequencies of the existing cable. Based on two orders, a set of equations relating the axial force of the beam fixed at both ends to its natural frequency is selected from the frequency method theory formula, and used as the basis for measuring the cable force of the existing cable. Its natural frequency Solve the system of equations between the given equations, including the first parameter. and the second parameter : First parameter The specific formula can be: ; in, This indicates the bending stiffness of the existing cables; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula can be: ; Step 3: Estimate the initial value of the bending stiffness of the existing cables based on the structural parameters and bending stiffness theoretical formulas. Based on the existing initial value of the bending stiffness of the cable And the second parameter lookup table, to determine the initial value of the second parameter. The initial range; Step 4: Based on the initial value of the second parameter From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter ; Step 5, based on the first parameter The existing cable bending stiffness was calculated using the formula. Then, the current value of the cable force is measured using the existing cables. and the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter If the initial range is determined, then proceed to step 6; if the second parameter... Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Proceed to step 3; this iterative calculation ensures the second parameter is... The range and the initial value of the second parameter The initial range is consistent, thus obtaining the final measured current value of the existing cable force. ; Step 6: Measure the current cable force based on the existing cables. and preset cable force Calculate the existing cable force The specific formula can be: .

[0026] By adding auxiliary cables and cable clamps, calculation conditions can be created that satisfy the equations relating the axial force of the beam fixed at both ends to its natural frequency. Then, the existing cable force and bending stiffness can be obtained by solving the relevant equations in the frequency method.

[0027] Furthermore, in step 1, a cable force is preset. It is an integer value not exceeding 10% of the design cable force.

[0028] Preferably, in step 1, the cable force is preset. It is 10 kN.

[0029] Furthermore, step 1 also includes installing a surface strain acquisition device on the existing cable between the two auxiliary cable clamps, and adjusting the cable force of the auxiliary cable to a preset cable force. Then, the strain change value of the existing cable was obtained through a surface strain acquisition device. This allows for the simultaneous acquisition of strain changes in the existing cables under the action of the auxiliary cables.

[0030] Furthermore, the method also includes step 7, based on the existing cable force. and the strain change value of the existing cables Calculate the axial stiffness of the existing cables The specific formula can be: .

[0031] Furthermore, when the first-order natural frequency of the existing cable is obtained in step 2... and the third natural frequency At that time, the cable force was measured using existing cables. Its natural frequency The systems of equations to be solved are as follows: ; .

[0032] Example 2: like Figure 2 As shown, this embodiment provides a system for measuring the tension of existing cables in a building structure, including a data receiving module, a data processing module, and a result generation module; The data receiving module is used to receive the preset cable force. The first and third natural frequencies of the existing cables Initial value of existing cable bending stiffness and the initial value of the second parameter ; The data processing module includes an equation unit, an iterative calculation unit, and a solution unit: The equation unit stores existing cable force measurements. Its natural frequencies of various orders Solving the system of equations, the formula for the first parameter C, and the formula for the second parameter. Formulas and existing cable forces The formula; The formula for the first parameter C can be: ; in, This indicates the bending stiffness of the existing cables; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula can be: ; Existing cable force The specific formula can be: ; The iterative calculation unit is based on the existing first and third order natural frequencies of the cable. Select the appropriate system of equations to solve; based on the initial value of the second parameter. From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter Based on the first parameter The formula was then retrieved to calculate the bending stiffness of the existing cable. Then, the current value of the cable force is measured using the existing cables. And retrieve the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter The initial range will be the current value of the existing cable force measurement. Send to the solver; if the second parameter Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Iterative calculation until the second parameter is obtained. Falling into the initial value of the second parameter The initial range; The solution unit measures the current value of the cable force based on the existing cable. and preset cable force Retrieve the existing cable force calculation formula and calculate the existing cable force. ; The result generation module is used to generate the existing cable force. and existing cable bending stiffness Outsourced.

[0033] Furthermore, the data receiving module is also used to receive the strain change values ​​of the existing cables. The equation unit also stores existing cable axial stiffness formulas. The solution unit is also based on the existing cable force. and the strain change value of the existing cables The axial stiffness of the existing cable is calculated using the existing cable axial stiffness formula. The result generation module is also used to generate the existing cable axial stiffness. Outsourced.

[0034] Example 3: This embodiment provides a device for measuring the tension of existing cables in a building structure, including a processor, a memory, and a bus. The memory stores instructions and data read by the processor, and the processor is used to call the instructions and data in the memory to execute the method for measuring the tension of existing cables in a building structure as described above. The bus connects the various functional components to transmit information.

[0035] In another implementation, this solution can be implemented using a device, which may include corresponding modules that perform one or more steps in the various embodiments described above. A module may be one or more hardware modules specifically configured to perform the corresponding step, or implemented by a processor configured to perform the corresponding step, or stored in a computer-readable medium for implementation by a processor, or implemented through some combination thereof.

[0036] The processor executes the various methods and processes described above. For example, the method implementations in this scheme can be implemented as software programs tangibly contained in a machine-readable medium, such as memory. In some implementations, part or all of the software program can be loaded and / or installed via memory and / or a communication interface. When the software program is loaded into memory and executed by the processor, one or more steps of the methods described above can be performed. Alternatively, in other implementations, the processor can be configured to execute one of the methods described above by any other suitable means (e.g., by means of firmware).

[0037] This device can be implemented using a bus architecture. A bus architecture can include any number of interconnect buses and bridges, depending on the specific application of the hardware and overall design constraints. The bus connects various circuits, including one or more processors, memory, and / or hardware modules. The bus can also connect various other circuits such as peripherals, voltage regulators, power management circuitry, external antennas, etc.

[0038] Buses can be Industry Standard Architecture (ISA) buses, Peripheral Component Interconnect (PCI) buses, or Extended Industry Standard Component (EISA) buses, etc. Buses can be divided into address buses, data buses, control buses, etc.

[0039] Furthermore, such as Figure 3 As shown, the building structure includes a cable tension measuring device, an auxiliary cable clamp 2, an auxiliary cable 3, a vibration sensor 4, and a strain sensor 5; A pair of auxiliary cable clamps 2 are installed between the cable clamps at both ends of the existing cable 1. The auxiliary cable clamps 2 should have sufficient bending stiffness compared with the existing cable 1 to restrain the bending deformation of the existing cable 1. Vibration sensors 4 (vibration frequency acquisition devices) are attached to the existing cable 1 between the two auxiliary cable clamps 2, and strain sensors 5 (surface strain acquisition devices) are attached along the axial direction of the existing cable 1. Auxiliary cables 3 are symmetrically arranged between the two auxiliary cable clamps 2, and the sum of the cable forces of the auxiliary cables is adjusted to a preset cable force.

[0040] The auxiliary cable clamp 2 comprises two symmetrical parts, such as... Figure 4 As shown, a first groove 21 for accommodating the existing cable 1 is provided at the center of the front half of the auxiliary cable clamp 2. A second groove 22 for accommodating the auxiliary cable 3 is symmetrically provided on both sides of the first groove 21. Several mounting holes 23 for locking the front and rear parts are evenly distributed on the connecting plate of the auxiliary cable clamp 2. When the front and rear parts of the auxiliary cable clamp 2 are locked together by several sets of bolts and nuts, a through hole is formed that allows the existing cable 1 and the auxiliary cable 3 to pass through respectively; the two ends of the auxiliary cable 3 are also provided with cable caps for limiting, which makes it easy for the auxiliary cable 3 to be tightened between the two auxiliary cable clamps 2.

[0041] The first-order natural frequency of a 50mm diameter steel cable fixed at both ends was simulated using Midas software. Figure 5As shown, its natural frequency is approximately 9.115 Hz; and using the aforementioned device, the first-order natural frequency of a 50 mm diameter steel cable was acquired, as shown... Figure 6 As shown, its natural frequency is approximately 9.077Hz, with a difference of only 0.8%, indicating that the device can achieve almost the same effect as a fixed constraint. Therefore, the equations relating the axial force of the beams fixed at both ends to their natural frequencies can be used for calculation.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the cable tension of existing cables in a building structure, characterized in that, include: Step 1: Install a pair of auxiliary cable clamps between the cable clamps at both ends of the existing cable; A vibration frequency acquisition device is installed on the existing cable between the two auxiliary cable clamps; auxiliary cables are symmetrically arranged between the two auxiliary cable clamps, and the cable force of the auxiliary cables is adjusted to a preset cable force. ; Step 2: Tap the existing cable and use a vibration frequency acquisition device to obtain the first and third natural frequencies of the existing cable. ; Based on two orders, a set of equations relating the axial force of the beam fixed at both ends to its natural frequency is selected from the frequency method theory formula, serving as the basis for measuring the cable force of existing cables. Its natural frequency Solve the system of equations between the two equations, including the first parameter. and the second parameter : The formula for the first parameter C is as follows: ； in, This indicates the existing bending stiffness of the cable; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula is as follows: ； Step 3: Estimate the initial value of the bending stiffness of the existing cables based on the structural parameters and bending stiffness theoretical formulas. Based on the existing initial value of the bending stiffness of the cable And the second parameter lookup table, to determine the initial value of the second parameter. The initial range; Step 4: Based on the initial value of the second parameter From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter ; Step 5: Based on the first parameter C and its formula, calculate the bending stiffness of the existing cable. Then, the current value of the cable force is measured using the existing cables. and the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter If the initial range is determined, then proceed to step 6; if the second parameter... Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Proceed to step 3; Step 6: Measure the current cable force based on the existing cables. and preset cable force Calculate the existing cable force The specific formula is as follows: .

2. The method according to claim 1, characterized in that, In step 1, the cable force is preset. It is an integer value not exceeding 10% of the design cable force.

3. The method according to claim 1, characterized in that, Step 1 further includes installing a surface strain acquisition device on the existing cable between the two auxiliary cable clamps, and adjusting the cable force of the auxiliary cable to a preset cable force. Then, the strain change value of the existing cable was obtained through a surface strain acquisition device. .

4. The method according to claim 3, characterized in that, The method further includes step 7, based on the existing cable force. and the strain change value of the existing cables Calculate the axial stiffness of the existing cables The specific formula is as follows: .

5. The method according to claim 1, characterized in that, When the first natural frequency of the existing cable is obtained in step 2 and the third natural frequency At that time, the cable force was measured using existing cables. Its natural frequency The systems of equations to be solved are as follows: ； 。 6. A system for measuring the tension of existing cables in a building structure, characterized in that, It includes a data receiving module, a data processing module, and a result generation module; The data receiving module is used to receive the preset cable force. The first and third natural frequencies of the existing cables Initial value of existing cable bending stiffness and the initial value of the second parameter ; The data processing module includes an equation unit, an iterative calculation unit, and a solution unit: The equation unit stores existing cable force measurements. Its natural frequencies of various orders Solving the system of equations and the first parameter The formula, the second parameter Formulas and existing cable forces The formula; First parameter The specific formula is as follows: ； in, This indicates the existing bending stiffness of the cable; This indicates the mass per unit length of the existing cable; Indicates the distance between the inner sides of the two auxiliary cable clamps; Second parameter The specific formula is as follows: ； Existing cable force The specific formula is as follows: ； The iterative calculation unit is based on the existing first and third order natural frequencies of the cable. Select the appropriate system of equations to solve; based on the initial value of the second parameter. From the solution systems of equations for the two orders, select the corresponding equations to determine the natural frequencies of the two orders. Substituting the values ​​into the two equations and solving them simultaneously, we can obtain the current value of the measured cable force of the existing cable. and the first parameter Based on the first parameter The formula was then retrieved to calculate the bending stiffness of the existing cable. Then, the current value of the cable force is measured using the existing cables. And retrieve the second parameter The formula is used to calculate the second parameter. Then perform a judgment: if the second parameter Falling into the initial value of the second parameter The initial range will be the current value of the existing cable force measurement. Send to the solver; if the second parameter Not falling into the initial value of the second parameter The initial range will then include the existing bending stiffness of the cables. As the initial value of the bending stiffness of existing cables Iterative calculation until the second parameter is obtained. Falling into the initial value of the second parameter The initial range; The solution unit measures the current value of the cable force based on the existing cable. and preset cable force Retrieve the existing cable force calculation formula and calculate the existing cable force. ; The result generation module is used to generate the existing cable force. and existing cable bending stiffness Outsourced.

7. The system according to claim 6, characterized in that, The data receiving module is also used to receive the strain change values ​​of the existing cables. The equation unit also stores existing cable axial stiffness formulas. ; The solution unit is also based on the existing cable force. and the strain change value of the existing cables The axial stiffness of the existing cable is calculated using the existing cable axial stiffness formula. The result generation module is also used to generate the existing cable axial stiffness. Outsourced.

8. A device for measuring the tension of existing cables in a building structure, characterized in that, It includes a processor, a memory, and a bus. The memory stores instructions and data read by the processor. The processor is used to call the instructions and data in the memory to execute the method as described in any one of claims 1 to 5. The bus connects the functional components for transmitting information.

9. The apparatus according to claim 8, characterized in that, It also includes auxiliary cable clamps, auxiliary cables, and vibration sensors; A pair of auxiliary cable clamps are installed between the cable clamps at both ends of the existing cable; a vibration sensor is attached to the existing cable between the two auxiliary cable clamps; and auxiliary cables are installed symmetrically between the two auxiliary cable clamps.

10. The apparatus according to claim 9, characterized in that, It also includes strain sensors, which are attached to the existing cable between the two auxiliary cable clamps along the axis of the existing cable.

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