Method for testing cable force of cable-supported structure by structural overall spatial form

Abstract

The application discloses a method for testing cable force of a cable-supported structure by overall spatial form of the structure, and utilizes the overall spatial form of the cable-supported structure to test the cable force of the cable, and determines the cable force of the cable by the actually measured overall spatial form of the structure, and comprises the following steps: S1, measuring the overall spatial form of the cable-supported structure; S2, modeling the cable-supported structure by using finite element software, and applying the cable force to simulate the spatial form of the cable-supported structure; S3, fitting the simulated spatial form and the actually measured spatial form by using the least square method; and S4, the cable force calculated by the finite element software corresponding to the minimum error is the cable force of the cable. The method is based on the method for testing the cable force of the cable-supported structure by the overall spatial form, simplifies the structure into a whole, and can ignore the influence of the sag and the bending stiffness, and the method is simple in calculation and strong in operability. The method is suitable for the soft cables such as steel wire bundles, steel strands and steel ropes and the hard cables of the continuous linking rigid cables in the cable-supported structure.

Description

Technical Field

[0001] This invention relates to the field of cable force monitoring technology, and in particular to a method for testing the cable force of a cable-supported structure through the overall spatial morphology of the structure. Background Technology

[0002] Cables are a crucial component of cable-stayed structures. Changes in cable forces not only affect the overall shape of the structure but also its internal force profile. Cable failure leads to severe degradation of structural stiffness, potentially causing the entire structure to fail. Monitoring cable forces in cable structures is essential to ensuring that prestressing reaches design goals during construction and that the structure remains safe during service life. Current cable force monitoring technologies require calculating parameters such as cable stiffness, sag, and length, which is complex. Furthermore, some cable force testing methods necessitate the use of cranes and boom lifts to install sensors on the structure during construction and service, consuming significant manpower and resources. Summary of the Invention

[0003] To address the shortcomings in the aforementioned background technology, this invention proposes a method for testing the cable force of a cable-stayed structure through the overall spatial morphology of the structure, which solves the problems of complex and costly cable force monitoring technology in the prior art.

[0004] The technical solution of this invention is implemented as follows: A method for testing cable forces in a cable-stayed structure using the overall spatial morphology of the structure, which utilizes the overall spatial morphology of the cable-stayed structure to test cable forces and determines cable forces based on the measured overall spatial morphology of the structure, includes the following steps: S1. Measured value of the overall spatial morphological change of the cable-supported structure; S2. The finite element method is used to model the cable-stayed structure and apply cable forces to the cables to simulate the spatial morphological changes of the cable-stayed structure. S3. The simulated spatial morphological change values ​​of the cable-supported structure are fitted with the measured spatial morphological change values ​​using the least squares method; S4. The cable force calculated by the finite element software corresponding to the minimum value of the least squares value is the cable force.

[0005] Furthermore, step S1 includes testing the overall spatial morphology of the cable-stayed structure using laser scanning or GPS positioning.

[0006] Furthermore, the spatial morphology of the cable-stayed structure includes the displacement of the cable-stayed structure before and after cable tensioning.

[0007] Furthermore, the spatial morphology of the cable-stayed structure includes the displacement of the struts and / or steel beams in the cable-stayed structure before and after cable tensioning.

[0008] Furthermore, the practical formula for the least squares fitting is: In the formula: D i - Least squares value; f j - Simulate and calculate the spatial morphological values ​​of the structure; f j ′ -Measured structural spatial morphology values.

[0009] The beneficial effects of this invention are as follows: This invention is based on a method for testing the cable force of a cable-stayed structure through the overall spatial shape, which simplifies the structure into a whole and can ignore the influence of sag and bending stiffness. The method is simple to calculate, highly operable, and does not require the installation of sensors on the structure, thus saving manpower and resources. This method is applicable to soft cables such as steel wire bundles, steel strands, and steel ropes in cable-stayed structures, and is also applicable to continuous rigid tension rods with rigid cables. Attached Figure Description

[0010] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the arrangement of deformation monitoring points for the cable-supported structure according to the present invention. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0013] The method for testing cable forces in a cable-stayed structure by means of the overall spatial morphology of the structure, as described in this invention, includes the following steps: First, laser scanning and GPS positioning methods were used to test the overall spatial morphological changes of the cable-stayed structure. The measured spatial morphological changes refer to the displacements of the struts and steel beams in space before and after cable tensioning, which can be expressed as displacement. After cable tensioning, the cable-stayed structure will arch, making displacement a more direct representation. The displacement can also be measured on select components, such as the mid-span, side spans, and quarter-spans of the cable-stayed structure; a portion of the struts can also be measured.

[0014] Then, a finite element model of the cable-stayed structure is created using finite element software, and cable forces are applied to the cables. The finite element software can be ABAQUS, ANSYS, MSC, or other finite element software. The process of applying the cable forces involves applying the designed cable forces to the finite element analysis model, comparing the calculated displacement changes with the measured displacement changes, and then adjusting the cable forces accordingly. Through this process, the spatial morphology of the cable-stayed structure under different cable forces is simulated. This spatial morphology refers to the displacement change of the cable-stayed structure before and after the application of cable forces, expressed in terms of displacement.

[0015] Next, the simulated spatial morphology of the cable-supported structure was fitted to the measured spatial morphology using the least squares method. The formula for calculating the least squares value is as follows: In the formula: Di - least squares value; fj - simulated structural spatial morphology value; fj′ - measured structural spatial morphology value.

[0016] Based on the calculated least squares value, the minimum value of the least squares value corresponds to the cable force, which is the cable force of the cable in the cable-stayed structure.

[0017] The following example uses a string-supported structure, such as... Figure 1 As shown in the figure, BX-1 to BX-6 are the deformation monitoring points of the cable-supported structure 1.

[0018] Table 1 shows the displacement difference calculation of the deformation monitoring points of the cable-supported structure in this engineering example, obtained through finite element software simulation and actual measurement. Table 1 Summary Table of Cable Force Identification and Calculation for Cable-Supported Structures According to the calculation results in Table 1, the minimum least squares frequency difference is 2.79, corresponding to a calculated cable force of 850 kN. Therefore, the lower chord cable of this cable-stayed structure is 850 kN. The cable force reading displayed on the pressure sensor of the on-site hydraulic gauge is 821.9 kN, a difference of 3.4%, demonstrating the feasibility of the cable force testing method based on the overall spatial morphology of the structure.

[0019] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing cable forces in a cable-stayed structure by examining the overall spatial morphology of the structure, characterized in that: The cable force is tested by utilizing the overall spatial morphology of the cable-stayed structure. This simplifies the structure as a whole, negligiblely reducing the influence of sag and bending stiffness. It eliminates the need for sensors on the cable-stayed structure. The cable force is determined through measured overall structural spatial morphology, including the following steps: S1. Measure the overall spatial morphological change value of the cable-supported structure. Select the mid-span, side span, quarter span and some strut positions of the cable-supported structure as monitoring points to obtain displacement. S2. The finite element method is used to model the cable-stayed structure and apply cable forces to the cables to simulate the spatial morphological changes of the cable-stayed structure. S3. The simulated spatial morphological change values ​​are fitted to the measured spatial morphological change values ​​using the least squares method; S4. The cable force calculated by the finite element software corresponding to the minimum value of the least squares value is the cable force. Step S1 includes testing the overall spatial morphological change value of the cable-stayed structure using laser scanning or GPS positioning. The spatial morphological change value of the cable-stayed structure includes the displacement of the struts and / or steel beams of the cable-stayed structure before and after cable tensioning; The formula for the least squares fitting method is as follows: In the formula: - Least squares value; - Simulate and calculate the spatial morphological values ​​of the structure; -Measured structural spatial morphology values.

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