Digital monitoring method for service state of prestressed cable of large-span pipe truss

Abstract

The invention relates to a digital monitoring method for the service state of a prestressed cable of a large-span pipe truss. The method comprises the following steps: S1, carrying out field investigation; s2, pasting a target; s3, on-site scanning; s4, generating a scanning point cloud model; s5, generating a compared scanning point cloud model; s6, constructing a comparison model; s7, calculating a deflection value; s8, compiling a service state monitoring data table of the prestressed cable; and S9, pre-stress failure judgment. According to the digital monitoring method adopted by the invention, the target is pasted, site cleaning and climbing operation are not needed when the long-span pipe truss prestressed inhaul cable in the service period is monitored, the monitoring work can be completed on the ground, the difficulty degree of the monitoring work is greatly reduced, the monitoring efficiency is remarkably improved, and the monitoring cost is reduced. And the safety and the reliability of the service state of the large-span prestressed pipe truss inhaul cable are ensured.

Description

Technical Field

[0001] The invention relates to the field of safe operation and maintenance of building engineering structures, and in particular to a digital monitoring method for the service status of prestressed cables of large-span tube trusses. Technical Background

[0002] As a new type of large-span space structure, the large-span prestressed cable tube truss structure has been widely used in dry coal sheds, gymnasiums, large workshops and other buildings in recent years due to its advantages of high space utilization, beautiful appearance and good economy. Prestressed cables can not only improve the overall rigidity of the structure, enhance the structural bearing capacity, optimize the structural stress state, but also adapt to the complex load and deformation requirements of large-span space structures. Therefore, it is particularly important to ensure that the prestress of the cable is stable and does not fail.

[0003] At present, the service status monitoring of prestressed cables of pipe trusses mainly relies on close monitoring by manually operated instruments. Since the height of prestressed cables of large-span pipe trusses is generally more than ten meters, close monitoring by humans requires the use of aerial platforms. However, the interior of dry coal sheds, gymnasiums, large workshops and other structures is usually filled with coal piles, seats, equipment, etc., and aerial platforms need to clear the route in advance before entering, making it extremely difficult to carry out monitoring of prestressed cables. Summary of the invention

[0004] The purpose of the present invention is to provide a digital monitoring method for the service status of prestressed cables of large-span tubular trusses, which can quickly and accurately monitor the service status of prestressed cables in service. When the cables are found to be loose and deflected, they can be repaired in time to ensure the overall safety of the structure.

[0005] The present invention is achieved in that: A digital monitoring method for the service status of a long-span tubular truss prestressed cable comprises the following steps: S1 On-site inspection: determine the position of each prestressed cable, number them, determine the route of 3D laser scanning, and determine the scanning station position of 3D laser scanning according to the scanning radius of the instrument; S2 Paste target: paste permanent targets with color difference on both ends and the middle of each prestressed cable; S3 On-site scanning: Complete scanning at the scanning site according to the route set in step S1; collect 3D scanning point cloud data for each prestressed cable one by one, and save the data of each prestressed cable separately in .asc format; S4 Generate a scanned point cloud model: import the on-site scan data of a prestressed cable .asc format file obtained in step S3 into Geomagic Studio software, click the open command of the software, select the .asc file to be imported and open it, and set the unit to millimeters; click cloud data import, color the point cloud, and then execute the non-connected items, external arc points, and reduce noise commands in sequence to remove redundant noise points; import the on-site scan data of each prestressed cable obtained in step S3 into Geomagic Studio software respectively, and generate a scanned point cloud model of each prestressed cable; S5 generating a comparative scanning point cloud model: the scanning point cloud data obtained for the first time is the first scanning point cloud data, and the scanning point cloud model generated for the first time is called the first scanning point cloud model; according to the monitoring cycle, the aforementioned steps S1-S4 are repeated for each prestressed cable at other time points, and comparative scanning point cloud data at different time points are respectively obtained to generate comparative scanning point cloud models at different time points; S6 Building a comparison model: Importing the first scan point cloud model and the comparison scan point cloud model of the same prestressed cable into Geomagic Studio software at the same time to build a comparison model; S7 calculates the deflection value: determines the deflection value of the prestressed cable according to the single point deviation value of the first scanning point cloud model generated at the middle position of each prestressed cable and the compared scanning point cloud model; S8 Prepare the service status monitoring data table of prestressed cables: record the monitoring data of each prestressed cable according to the monitoring cycle; S9 Prestress failure judgment: When the deflection value of a prestressed cable changes significantly, it means that it has relaxed and the prestress has failed.

[0006] Preferably, when generating the first scan point cloud model, step S4, after the first cloud data is imported and redundant noise is removed, also includes the following steps: encapsulating the first scanned prestressed cable three-dimensional scanning point cloud model to form an irregular triangular TIN mesh model, and renaming the point cloud model for later search.

[0007] Preferably, the permanently attached target with color difference described in step S2 is a black and white target that is convenient for the subsequent capture and correction of the three-dimensional scanning point cloud and can ensure the scanning accuracy.

[0008] Preferably, the pattern of the black and white target is divided into four equal parts symmetrically with a center, with a cross target line at the center, and the black and white areas on the target pattern are arranged alternately.

[0009] Preferably, after importing the two models in step S6, the irregular triangular TIN mesh model generated by the first scan is set as "reference", and the point cloud model obtained by the comparison scan is set as "test", and then the automatic alignment command is executed to align the two models. If the automatic alignment fails, the permanent targets pasted at both ends and the middle of the prestressed cable can be used for manual grabbing and alignment; the operation method of manual grabbing and alignment is to overlap the cross target lines in the black and white targets in the first scanned point cloud model and the compared scanned point cloud model; the successfully aligned comparison models are compared in 3D to generate a model deviation chromatogram, and the middle position is selected according to the characteristics of the prestressed cable to generate a single-point deviation value, that is, the deflection value of the prestressed cable.

[0010] The digital monitoring method adopted by the present invention, in addition to sticking targets, does not require site clearing and height climbing when monitoring the large-span prestressed tube truss cables in service, and the monitoring work can be completed on the ground, which greatly reduces the difficulty of the monitoring work and significantly improves the monitoring efficiency, ensuring the safety and reliability of the service status of the large-span prestressed tube truss cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the overall structure of the prestressed cable tube truss; Figure 2 Schematic diagram of transverse section of the overall structure of prestressed cable tube truss; Figure 3 Schematic diagram of black and white targets in the embodiment; Figure 4 Schematic diagram of the position of the black and white targets pasted on a prestressed cable in the embodiment; Figure 5 Schematic diagram of scanning sites and scanning paths in an embodiment. DETAILED DESCRIPTION

[0012] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. Embodiment The service status of the prestressed cables of the large-span pipe trusses used in the dry coal shed is digitally monitored.

[0013] Figure 1 This is a schematic diagram of the overall structure of a large-span prestressed cable-tube truss. Figure 2 is a transverse section of the overall structure of the prestressed cable-tube truss. Figure 1 is a tube truss and 2 is a prestressed cable. In actual use, all prestressed cables should be in a tensioned state.

[0014] When digitally monitoring the service status of prestressed cables, the following steps are taken: S1 On-site inspection: determine the position of each prestressed cable and number them. The dry coal shed in the embodiment uses 27 prestressed cables; determine the route of the 3D laser scanning according to the large-span tube truss structure drawings and on-site inspection, see Figure 5 The scanning station position of the three-dimensional laser scanning is determined according to the scanning radius of the instrument. The embodiment adopts 27 stations, namely A1, A2...A27. At each station, the laser scanning of the entire route is completed in a return manner in the direction of the arrow.

[0015] S2 Paste the target: To ensure the scanning accuracy, permanent black and white targets are pasted on both ends and the middle of each prestressed cable to facilitate the capture and correction of the 3D scanning point cloud in the later stage. The pattern of the permanent black and white target in the embodiment is as follows: Figure 3 As shown, Figure 4 Shown is the location where a permanent bonded target is bonded to a prestressed cable.

[0016] S3 On-site scanning: According to the route set in step S1, complete the scanning at 27 scanning sites respectively; determine that each prestressed cable is within the scanning range, collect 3D scanning point cloud data for each prestressed cable one by one, and save the data of each prestressed cable separately in .asc format; S4 Generate a scanned point cloud model: import the on-site scan data of a prestressed cable .asc format file obtained in step S3 into Geomagic Studio software, click the open command of the software, select the .asc file to be imported and open it, and set the unit to millimeters; click cloud data import, color the point cloud, and then execute the non-connected items, external arc points, and reduce noise commands in sequence to remove redundant noise points; import the on-site scan data of each prestressed cable obtained in step S3 into Geomagic Studio software respectively, and generate a scanned point cloud model of each prestressed cable; S5 Generate a comparative scanning point cloud model: the scanning point cloud data obtained for the first time is the first scanning point cloud data, and the scanning point cloud model generated for the first time is called the first scanning point cloud model; in this embodiment, three months is used as a monitoring period, and the aforementioned steps S1-S4 are repeated for each prestressed cable at a corresponding time point, and comparative scanning point cloud data at different time points are respectively obtained to generate comparative scanning point cloud models at different time points; S6 Constructing a comparative model: Import the first scanned point cloud model and the comparative scanned point cloud model of the same prestressed cable into Geomagic Studio software at the same time. After importing the two models, set the irregular triangle TIN mesh model generated by the first scan as "reference", and set the point cloud model obtained by the comparative scan as "test", and then execute the automatic alignment command to align the two models. If the automatic alignment fails, the permanent targets pasted at both ends and the middle of the prestressed cable can be used for manual grabbing and alignment; the operation method of manual grabbing and alignment is to overlap the cross target lines in the black and white targets in the first scanned point cloud model and the comparative scanned point cloud model; compare the successfully aligned comparative models in 3D, generate a model deviation chromatogram, and select the middle position according to the characteristics of the prestressed cable to generate a single-point deviation value, that is, the deflection value of the prestressed cable.

[0017] S7 calculates the deflection value: determines the deflection value of the prestressed cable according to the single point deviation value of the first scanning point cloud model generated at the middle position of each prestressed cable and the compared scanning point cloud model; S8 Prepare the service status monitoring data table of prestressed cables: record the monitoring data of each prestressed cable according to the monitoring cycle; S9 Prestress failure judgment: When the deflection value of a tensioned prestressed cable changes significantly, it indicates that it has been relaxed and the prestress has failed. In actual monitoring, due to the influence of equipment, distance, and environmental factors, three-dimensional laser scanning will have errors. This embodiment takes into account the scanning error. When the deflection value of a tensioned prestressed cable is greater than 5mm, it is considered to be a prestress failure and needs to be repaired.

Claims

1. A digital monitoring method for the service status of prestressed cables of large-span tube trusses, characterized in that: The following steps are involved: S1 On-site inspection: determine the position of each prestressed cable, number them, determine the route of 3D laser scanning, and determine the scanning station position of 3D laser scanning according to the scanning radius of the instrument; S2 Paste target: paste permanent targets with color difference on both ends and the middle of each prestressed cable; S3 On-site scanning: Complete scanning at the scanning site according to the route set in step S1; collect 3D scanning point cloud data for each prestressed cable one by one, and save the data of each prestressed cable separately in .asc format; S4 Generate a scanned point cloud model: import the field scan data of a prestressed cable .asc format file obtained in step S3 into Geomagic Studio software, click the open command of the software, select the .asc file to be imported and open it, and set the unit to millimeter; Click on cloud data import to color the point cloud, and then execute the non-connected items, external arc points, and noise reduction commands in sequence to remove redundant noise points; import the field scanning data of each prestressed cable obtained in step S3 into the Geomagic Studio software, and generate a corresponding scanning point cloud model of each prestressed cable; S5 generating a comparative scanning point cloud model: the scanning point cloud data obtained for the first time is the first scanning point cloud data, and the scanning point cloud model generated for the first time is called the first scanning point cloud model; according to the monitoring cycle, the aforementioned steps S1-S4 are repeated for each prestressed cable at other time points, and comparative scanning point cloud data at different time points are respectively obtained to generate comparative scanning point cloud models at different time points; S6 Building a comparison model: Importing the first scan point cloud model and the comparison scan point cloud model of the same prestressed cable into Geomagic Studio software at the same time to build a comparison model; S7 calculates the deflection value: determines the deflection value of the prestressed cable according to the single point deviation value of the first scanning point cloud model generated at the middle position of each prestressed cable and the compared scanning point cloud model; S8 Prepare the service status monitoring data table of prestressed cables: record the monitoring data of each prestressed cable according to the monitoring cycle; S9 Prestress failure judgment: When the deflection value of a prestressed cable changes significantly, it means that it has relaxed and the prestress has failed.

2. The digital monitoring method for the service status of the prestressed cables of the long-span tubular truss according to claim 1 is characterized by: When generating the first scan point cloud model, step S4 also includes the following steps after the first cloud data is imported and redundant noise is removed: encapsulating the first scanned prestressed cable three-dimensional scan point cloud model to form an irregular triangle TIN grid model, and renaming the point cloud model for later search.

3. The digital monitoring method for the service status of the prestressed cables of the long-span tubular truss according to claim 1 or 2 is characterized in that: The permanently attached target with color difference described in step S2 is a black and white target that can ensure scanning accuracy in order to facilitate the capture and correction of the three-dimensional scanning point cloud in the later stage.

4. The digital monitoring method for the service status of the prestressed cables of the long-span tubular truss according to claim 3 is characterized by: The pattern of the black and white target is divided into four equal parts symmetrically from the center, with a cross target line in the center, and the black and white areas on the target pattern are arranged alternately.

5. The digital monitoring method for the service status of the prestressed cables of the long-span tubular truss according to claim 4 is characterized by: Step S6: After importing the two models, the irregular triangle TIN mesh model generated by the first scan is set as "reference", and the point cloud model obtained by the comparison scan is set as "test", and then the automatic alignment command is executed to align the two models. If the automatic alignment fails, the permanent targets attached to the ends and the middle of the prestressed cable can be used for manual grabbing and alignment; The operation method of manual grasping alignment is to overlap the cross target lines in the black and white targets in the first scanned point cloud model and the compared scanned point cloud model; perform a 3D comparison on the successfully aligned comparison models, generate a model deviation chromatogram, and select the middle position according to the characteristics of the prestressed cable to generate a single-point deviation value, that is, the deflection value of the prestressed cable.

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