Intelligent sensing precast assembly prestressed concrete frame whole process monitoring method

Abstract

The present application relates to a kind of intelligent perception prefabricated assembly prestressed concrete frame whole process monitoring method, comprising the following steps: design, make optical fiber composite stranded wire;Calibrate optical fiber composite stranded wire and sensor;Optical fiber composite stranded wire and each sensor are placed in prefabricated beam and prefabricated column;Real-time monitoring is carried out to structure by optical fiber composite stranded wire and sensor;The internal force state of component is analyzed and evaluated.The monitoring method will traditional structure be promoted to intelligent perception structure, can the stress of steel bar and prestressed tendon, concrete strain, concrete crack width, component displacement and angle of variation such as key position and control section of node center position, beam-column interface, beam span, column foot and column top are monitored in stage, region whole life cycle, and the real stress state and structure performance of real-time monitoring structure are provided with guarantee.

Description

Technical Field

[0001] This invention relates to the fields of prefabricated building and intelligent building monitoring technology, and in particular to a method for intelligently sensing and monitoring the entire process of precast prestressed concrete frames. Background Technology

[0002] Promoting new-type industrialized construction and intelligent construction is an important way to develop supply-side reform in the housing and urban-rural construction sector, transform and upgrade the construction industry, and promote green and low-carbon development. It is of great significance for reducing resource consumption and improving the level of industrialization and intelligence in engineering construction. Industrialized construction is an inevitable development trend of my country's construction industry now and in the future, and prefabricated construction is an effective way to achieve industrialized construction.

[0003] Furthermore, intelligent sensing, intelligent monitoring, intelligent construction, and intelligent operation and maintenance have gradually become the main trends in the future development of urban buildings.

[0004] However, currently, during the construction, use, and operation of buildings, variables such as stress in steel bars and prestressed tendons, concrete strain, concrete crack width, component displacement, and rotation in key components and control sections are mainly detected manually. Due to the technical characteristics of this method, measurements are only taken after potential hazards have occurred, making it impossible to monitor the structural safety status in real time. The main factors leading to a series of safety accidents are often subtle changes in the building itself, accumulated over years. These subtle changes cannot be detected by manual measurement alone, and manual inspection alone is insufficient for precise management, easily leading to missed inspections and potential safety hazards.

[0005] Furthermore, in traditional precast prestressed assembled structures, the prestress in the precast beams undergoes prestress loss during construction, including after concrete pouring and tensioning, during stacking, transportation, and hoisting. This prestress continues to be lost during the use of the assembled structure, exerting additional stress on surrounding columns, walls, and other components. However, the prestress loss and the actual remaining prestress cannot be measured during these processes; data is only estimated based on various assumptions or monitored using data acquisition equipment installed after construction. However, this method can only detect relative prestress values, not absolute prestress values, and these calculated or measured results often differ significantly from the actual values.

[0006] Currently, it is impossible to conduct real-time and effective assessments of structural performance throughout its entire life cycle, nor can the future performance of the structure be predicted. Overall, the level of intelligence in building structures remains relatively low. Therefore, to further improve the safety and reliability of prefabricated structures, it is necessary to further upgrade and optimize the monitoring methods for these structures. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the prestress in prefabricated assembled structures cannot be accurately monitored throughout the entire process in the prior art, and to provide a method for intelligently sensing the prestress of prefabricated assembled concrete frames to monitor the entire process, which can monitor various mechanical performance indicators such as stress and strain in real time throughout the entire life cycle. These data can provide a basis and early warning for the inspection, maintenance and possible damage of the structure, and further improve the safety and reliability of the structure.

[0008] To address the aforementioned technical problems, this invention provides a method for intelligently sensing and monitoring the entire process of precast prestressed concrete frames. The concrete frame structure includes reinforced concrete columns, beam-column joints, precast prestressed beams, prestressed steel strands, and fiber optic composite strands.

[0009] The beam-column joint is cast on the reinforced concrete column, including: the pre-cast part of the beam-column joint and the post-cast part of the beam-column joint;

[0010] The precast prestressed beam is connected to the reinforced concrete column through the beam-column joint;

[0011] The prestressed steel strands are distributed at the upper and lower parts of the precast prestressed beam. Both ends of the prestressed steel strands extend from the precast prestressed beam. Specifically, the prestressed steel strands located at the lower part of the precast prestressed beam are bent at 90° and anchored to the beam-column joint via a bending anchoring method. The remaining prestressed steel strands located at the upper and lower parts of the precast prestressed beam are not bent. After the cast-in-place concrete in the joint area reaches its design strength, the extended portions are post-tensioned using anchors and anchor plates to apply prestress to the concrete in the beam-column joint area. At least one secondary-tensioned fiber optic composite strand replaces the prestressed steel strands, and at least one bent-anchored fiber optic composite strand replaces the prestressed steel strands. The fiber optic composite strand includes at least one optical fiber.

[0012] The whole-process monitoring method includes the following steps:

[0013] S1. Design and manufacture fiber optic composite stranded cables;

[0014] S2. Calibrate the fiber optic composite twisted cable to determine the sensing parameters of the internal optical fiber under different load conditions.

[0015] S3. Prepare prestressed beams;

[0016] S3-1. Fix and tension the prestressed steel strands and fiber optic composite strands. Distribute the prestressed steel strands and fiber optic composite strands at the upper and lower parts of the corresponding positions of the precast prestressed beam, and monitor and record the prestress value of the fiber optic composite strands.

[0017] S3-2. Fix and calibrate each sensor used for monitoring, and lay the sensor and fiber optic composite twisted cable at the monitoring position to monitor the changes of each mechanical parameter in real time.

[0018] S3-3, formwork erection, pouring concrete for beams and columns to prepare precast prestressed beams, and monitoring and recording the prestress value of fiber optic composite stranded wires;

[0019] S3-4. Deform and release the prestressed beam, and continuously monitor and record the prestress value of the fiber optic composite stranded wire.

[0020] S4. Bend the prestressed steel strands and optical fiber composite strands that extend from the bottom of the prestressed beam at 90°.

[0021] S5. Transport and hoist precast prestressed beams and reinforced concrete columns, pour concrete for the post-cast portion of the beam-column joint, anchor the bent prestressed steel strands and fiber optic composite strands in the beam-column joint, and monitor and record the prestress value of the fiber optic composite strands.

[0022] S6. After the cast-in-place concrete in the joint area reaches the design strength, the prestressed steel strands and fiber composite strands extending from the beam ends are post-tensioned using the post-tensioning method to apply prestress to the concrete in the beam-column joint area, and the prestress value of the fiber composite strands is monitored and recorded.

[0023] S7. After the structure is constructed, during the structural use phase, monitor and record the changes in various mechanical parameters of the structure in real time.

[0024] S8. Based on the parameter changes monitored and recorded in step S7, analyze and evaluate the internal force state of the structure and components, and determine whether the structure has been damaged.

[0025] S9. When the changes in the internal forces of a component endanger the structural safety, the system will automatically issue an early warning and repair, reinforce, or replace the component; when the changes in the internal forces of a component are within a safe range, the structure does not require maintenance and can continue to be used.

[0026] S10. After the structure reaches the end of its service life, the structure will be dismantled, and intelligent monitoring will end.

[0027] In one embodiment of the present invention, in step S1, gratings are processed at corresponding positions of the pre-tensioned section, post-tensioned section and bending section on the optical fiber inside the optical fiber composite stranded cable, and the gratings are marked and numbered.

[0028] In one embodiment of the present invention, step S2, the step of calibrating the optical fiber composite twisted cable, includes:

[0029] S2-1. Record the wavelength of the fiber optic composite stranded wire when it is not tensioned, and use it as the initial wavelength;

[0030] S2-2, Tension the fiber optic composite stranded wire to 5kN for pre-tightening;

[0031] S2-3. Load the fiber optic composite stranded wire at 20KN increments, up to 80% of its ultimate load capacity. Keep the loading speed within 10KN / min. Hold each loading step for 5 minutes and record the corresponding wavelength.

[0032] S2-4. After recording the wavelength corresponding to the specified load, hold the load for 15 minutes and observe whether there are any abnormalities or even failures in the fiber optic grating signal transmission. After confirming that there are no errors, unload the load step by step to 0.

[0033] S2-5. Repeat steps S2-2 to S2-4 5 times and take the average value for calibration calculation.

[0034] In one embodiment of the present invention, in step S3-1, the optical fiber composite stranded wire is fixed at the designed position in the precast prestressed beam, and the optical fiber composite stranded wire and the prestressed steel strand are tensioned synchronously. The acquisition device automatically records the tension value of the first tensioned section of the optical fiber composite stranded wire during the tensioning process. After the design value is reached, the tensioning is stopped, and the two ends of the tensioning platform are temporarily anchored to prevent the prestress from decreasing. The tension values ​​of the second tensioning of the optical fiber composite stranded wire and the bending and anchoring of the first tensioned section of the optical fiber composite stranded wire are recorded during this stage.

[0035] In one embodiment of the present invention, in step S3-2, the sensor includes:

[0036] Embedded sensors include: reinforcement stress gauges, strain gauges and joint gauges. During the fabrication of each component, these embedded sensors are cast into the concrete at key control sections such as the center of the node, the beam-column interface, the mid-span of the beam, the column base and the column top.

[0037] The reinforcement stress gauge is fixed to the stirrups, column reinforcement, and energy-dissipating reinforcement at key locations of the reinforced concrete column, precast prestressed beam, and beam-column joint.

[0038] The strain gauges are placed in areas of large concrete deformation, such as reinforced concrete columns, precast prestressed beams, and beam-column joints.

[0039] The crack gauge is placed at the junction of the precast prestressed beam and the beam-column joint, the plastic hinge zone between the precast prestressed beam and the reinforced concrete column, and at locations where diagonal cracks may appear at the beam-column joint.

[0040] In one embodiment of the present invention, in step S3-2, the sensor includes:

[0041] External sensors, including laser rangefinders, temperature and humidity sensors, anemometers, inclinometers, and accelerometers, are mounted on the surface of the structure.

[0042] The laser rangefinder and the inclinometer are fixed to the surface of the upper end of the column facing another column;

[0043] The temperature and humidity sensor, anemometer, and accelerometer are fixed to the floor slab of the top floor of the structure.

[0044] In one embodiment of the present invention, in step S3-3, after the template of the precast prestressed beam is set up, concrete is poured. During the pouring and curing process, the tension change in the steel strand is continuously collected and recorded through the fiber composite strand. The tension values ​​of the secondary tensioning fiber composite strand and the pre-tensioned section of the bent anchoring fiber composite strand are recorded at this stage.

[0045] In steps S3-4, after curing to the design strength, tension is released. During the release process, the tension changes in the upper and lower steel strands in the beam are continuously collected and recorded through fiber optic composite stranded wires. The tension values ​​of the secondary tensioning fiber optic composite stranded wires and the pre-tensioned sections of the bent anchoring fiber optic composite stranded wires are also recorded. After the release is completed, the strain of the concrete in the upper and lower mid-span of the precast prestressed beam is continuously collected and recorded during the release process.

[0046] In one embodiment of the present invention, step S5 includes the following steps:

[0047] S5-1. After the tensioning is completed, the precast prestressed beams are hoisted to the warehouse for stacking, and then transported to the construction site for hoisting. The tension values ​​of the pre-tensioned section of the secondary tensioned fiber composite stranded wire and the bent anchored fiber composite stranded wire are continuously recorded.

[0048] S5-2. After hoisting is completed, start pouring concrete for the post-cast portion of the beam-column joint. Record the force value of the bent section of the bending anchor steel strand during the pouring and curing process.

[0049] In one embodiment of the present invention, in step S7, the acquisition device automatically acquires and records the prestress values ​​of the pre-tensioned and post-tensioned sections of the optical fiber composite stranded wire, as well as the force value of the bending section. At the same time, each sensor performs real-time monitoring and recording, and uploads the data to the cloud server in real time.

[0050] In one embodiment of the present invention, the sensor is integrated with an Internet of Things (IoT) architecture, cloud computing, seamless connection technology of local area networks or communication networks, and parallel intelligent processing technology of massive node data through a matching transmission device to establish a complete real-time structural safety monitoring system.

[0051] The technical solution of the present invention has the following advantages compared with the prior art:

[0052] The intelligent sensing precast prestressed concrete frame whole-process monitoring method described in this invention combines a structural form with various built-in sensors to upgrade traditional structures into intelligent structures. At the structural level, it can collect real-time data on variables such as the stress of steel bars and prestressing tendons, concrete strain, concrete crack width, component displacement, and rotation at key parts and control sections of each component. At the component level, it can monitor various mechanical performance indicators such as stress and strain throughout the entire life cycle. This data can provide a basis and early warning for structural inspection, maintenance, and potential damage, further improving the safety and reliability of the structure.

[0053] In the concrete frame of this invention, beams, columns, and other components are prefabricated. Various sensors and fiber optic composite stranded cables are embedded in the components during the manufacturing process, enabling full-process monitoring of the internal forces and deformation of the components throughout their entire lifecycle, from production, stacking, transportation, hoisting, use, to dismantling. Based on the recorded changes in prestress values ​​of the fiber optic composite stranded cables at different stages and in different areas, the actual prestress loss values ​​of the prefabricated prestressed beams at different stages and in different areas under various load conditions can be calculated, providing a reference and basis for the subsequent optimized design of this type of component. Attached Figure Description

[0054] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0055] Figure 1 This is a flowchart illustrating the intelligent sensing method for monitoring the entire process of precast prestressed concrete frames according to the present invention.

[0056] Figure 2 This is a schematic diagram of the overall intelligent monitoring system of the present invention;

[0057] Figure 3 This is a partial layout diagram of the intelligent monitoring system of the present invention;

[0058] Figure 4 This is a schematic diagram of the column-end sensor arrangement of the present invention;

[0059] Figure 5 This is a schematic diagram of the sensor arrangement in the node area of ​​the present invention;

[0060] Figure 6 This is a schematic diagram of the arrangement of column reinforcement sensors in the node area according to the present invention;

[0061] Figure 7 This is a schematic diagram of the beam end sensor arrangement according to the present invention;

[0062] Figure 8 This is a schematic diagram of the optical fiber composite stranded wire structure of the present invention;

[0063] Figure 9 This is a schematic diagram of the cross-section of the optical fiber composite stranded wire of the present invention;

[0064] Figure 10 This is a schematic diagram of the axial cross-section of the center wire of the optical fiber composite stranded wire of the present invention;

[0065] Figure 11 This is a schematic diagram of the distribution of the bent optical fiber composite stranded grating of the present invention;

[0066] Figure 12 This is a schematic diagram of the distribution of the post-tensioned fiber composite stranded grating of the present invention;

[0067] Explanation of reference numerals in the accompanying drawings: 1. Reinforced concrete column; 2. Beam-column joint; 201. Precast portion of beam-column joint; 202. Postcast portion of beam-column joint; 3. Precast prestressed beam; 4. Column stirrups; 5. Column reinforcement; 6. Composite layer reinforcement; 7. Beam stirrups; 8. Reinforcement stress gauge; 9. Strain gauge; 10. Joint gauge; 11. Secondary tension prestressed steel strand; 12. Bent anchorage steel strand; 13. Anchorage; 14. Anchor plate; 15. Fiber optic composite strand; 1501. Center wire; 1502. Edge wire; 1503. Fiber optic cable; 1504. Grating; 16. Tensioning groove; 17. Composite floor slab; 18. Laser rangefinder; 19. Temperature and humidity sensor; 20. Anemometer; 21. Inclinometer; 22. Accelerometer; 23. Multi-channel fiber optic strain gauge; 24. Field database; 25. Field monitoring room terminal; 26. Intelligent sensor acquisition device; 27. Wireless data transmission equipment; 28. Cloud server; 29. ​​Switch; 30. Remote monitoring room terminal; 31. Remote database; 32. Carrier base station; 33. Mobile terminal; 34. Reinforcing mesh; 35. Secondarily tensioned fiber optic composite stranded cable; 36. Bending and anchoring fiber optic composite stranded cable; 37. Optical cable; 38. Signal cable. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0069] The intelligent sensing method for monitoring the entire process of precast prestressed concrete frames of the present invention refers to... Figures 2-7As shown, the precast prestressed concrete frame includes: reinforced concrete column 1, beam-column joint 2, precast prestressed beam 3, prestressed steel strands, fiber optic composite stranded wire 15, and sensors. The reinforced concrete column 1, beam-column joint 2, and precast prestressed beam 3 constitute a concrete frame structure. The prestressed steel strands are distributed at the upper and lower parts of the precast prestressed beam 3. Both ends of the prestressed steel strands extend from the precast prestressed beam. Specifically, the prestressed steel strands located at the lower part of the precast prestressed beam are bent at 90° (i.e., bent anchoring steel strands 12) and anchored to the beam-column joint by bending anchoring. The remaining prestressed steel strands located at the upper and lower parts of the precast prestressed beam are not bent (i.e., secondary tensioning steel strands 11). After the cast-in-place concrete in the joint area reaches its design strength, the extended parts are post-tensioned using anchorages and anchor plates to apply prestress to the concrete in the beam-column joint area.

[0070] The fiber optic composite strand 15 is used to replace the prestressed steel strand. Among the multiple secondary tensioned steel strands 11, at least one secondary tensioned fiber optic composite strand 35 is provided to replace the prestressed steel strand. Among the multiple bent anchoring steel strands 12, at least one bent anchoring fiber optic composite strand 36 is provided to replace the prestressed steel strand. The fiber optic composite strand 15 includes at least one optical fiber 1503. The sensor is embedded at the center of the beam-column node 2, the beam-column interface, the beam inflection point, the beam mid-span, the column inflection point, the column base, and the column top, which are the locations where stress changes need to be closely monitored.

[0071] Specifically, the reinforced concrete column 1 can be prefabricated in a factory or cast on-site; the column contains column reinforcement 5 and column stirrups 4, and a beam-column joint 2 is provided at the top of the column.

[0072] The beam-column joint 2 is poured in two stages. The first stage is the first part 201 of the beam-column joint, which is poured together with the column below the beam-column joint 2. The second stage is the second part 202 of the beam-column joint, which is poured after the precast prestressed beam 3 is hoisted to the design position.

[0073] The beam-column joint 2 is made of cast-in-place concrete, and a tensioning groove 16 is reserved at the design position during pouring; the tensioning groove 16 is located between the vertical intersection line of the beam and column and the vertical edge line of the column.

[0074] The precast prestressed beam 3 is a precast prestressed composite beam, with composite layer steel bars 6 and beam stirrups 7 in the beam; the precast prestressed beam 3 is precast in the factory, and after the beam is hoisted into place, the floor slab 17 is cast on the beam in place at the construction site.

[0075] In the anchorage zone concrete of the precast prestressed beam 3 and beam-column joint 2 after tensioning, a certain number of steel mesh 34 are arranged to enhance the local splitting resistance of the anchorage zone concrete. The specific number of steel mesh 34 and the diameter of the steel bars are determined by calculation.

[0076] Based on the aforementioned precast prestressed concrete frame, referring to Figure 1 As shown, this invention discloses a method for intelligent sensing and monitoring of the entire process of precast prestressed concrete frames, comprising the following steps:

[0077] S1. Design and manufacture 15 fiber optic composite stranded cables;

[0078] S2. Calibrate the fiber composite twisted cable 15 to determine the sensing parameters of the internal optical fiber under different load conditions.

[0079] S3. Fabrication of prestressed beams;

[0080] S3-1. Fix and tension the prestressed steel strands and fiber optic composite strands 15. Distribute the prestressed steel strands and fiber optic composite strands 15 at the upper and lower parts of the corresponding positions of the precast prestressed beam, and monitor and record the prestress value of the fiber optic composite strands 15.

[0081] S3-2. Fix and calibrate each sensor used for monitoring, and lay the sensor and fiber optic composite twisted cable 15 at the monitoring position to monitor the changes of each mechanical parameter in real time.

[0082] S3-3, formwork erection, pouring concrete for beams and columns to prepare precast prestressed beams, and monitoring and recording the prestress value of fiber optic composite stranded wire 15;

[0083] S3-4. Deform and release the prestressed beam, and continuously monitor and record the prestress value of the fiber optic composite stranded wire 15.

[0084] S4. Bend the prestressed steel strands and optical fiber composite strands 15 that extend from the bottom of the precast prestressed beam at 90°.

[0085] S5. Transport and hoist precast prestressed beams and reinforced concrete columns, pour concrete for the post-cast portion of the beam-column joint, anchor the bent prestressed steel strands and fiber composite strands 15 in the beam-column joint, and monitor and record the prestress value of the fiber composite strands 15.

[0086] S6. After the cast-in-place concrete in the joint area reaches the design strength, the prestressed steel strands and fiber composite strands 15 extending from the beam end are post-tensioned by post-tensioning method to apply prestress to the concrete in the beam-column joint area, and the prestress value of the fiber composite strands 15 is monitored and recorded.

[0087] S7. After the structure is constructed, during the structural use phase, monitor and record the changes in various mechanical parameters of the structure in real time.

[0088] S8. Based on the parameter changes monitored and recorded in step S7, analyze and evaluate the internal force state of the structure and components, and determine whether the structure has been damaged.

[0089] S9. When the changes in the internal forces of a component endanger the structural safety, the system will automatically issue an early warning and repair, reinforce, or replace the component; when the changes in the internal forces of a component are within a safe range, the structure does not require maintenance and can continue to be used.

[0090] S10. Upon completion of the structure's service life, the structure will be dismantled, and intelligent monitoring will cease.

[0091] The intelligent sensing precast prestressed concrete frame whole-process monitoring method described in this invention combines a structural form with various built-in sensors to upgrade traditional structures into intelligent structures. At the structural level, it can collect real-time data on variables such as the stress of steel bars and prestressing tendons, concrete strain, concrete crack width, component displacement, and rotation at key parts and control sections of each component. At the component level, it can monitor various mechanical performance indicators such as stress and strain throughout the entire life cycle. This data can provide a basis and early warning for structural inspection, maintenance, and potential damage, further improving the safety and reliability of the structure.

[0092] Specifically, refer to Figures 8-10 As shown, in step S1, the optical fiber composite stranded cable 15 includes: a center wire 1501 and multiple side wires 1502 twisted around the center wire 1501 and covering its outer periphery. The center wire 1501 is a carbon fiber rod, and the optical fiber 1503 is inserted in the carbon fiber rod. In this embodiment, the optical fiber composite stranded cable 15 is formed by twisting the six surrounding side wires 1502 around the central center wire 1501 with a certain twist pitch. The optical fiber 1503 is used as a detection unit in the sensor, which can detect stress changes at any position on the entire optical fiber 1503.

[0093] Specifically, in order to ensure the strength of the optical fiber composite stranded wire 15, the material of the edge wire 1502 is the same as that of the prestressed steel strand, so that the optical fiber composite stranded wire 15 can act as a reinforcing bar to withstand tensile force.

[0094] Specifically, to further improve the accuracy of the measurement, gratings 1504 are fabricated at corresponding positions on the pre-tensioned section, post-tensioned section, and bending section of the optical fiber 1503 inside the optical fiber composite twisted cable 15. The gratings 1504 are marked and numbered, and referenced... Figure 11 and Figure 12As shown, the secondary tensioned fiber composite stranded cable 35 includes a pre-tensioned section embedded in the precast prestressed beam 3 and a post-tensioned section extending out of the precast prestressed beam 3. The pre-tensioned section is engraved with gratings 1504 (EX-1 to EX-7), and the optical fibers in the post-tensioned section are engraved with gratings 1504 (EH-1 to EH-10). The bent anchoring fiber composite stranded cable 36 includes a pre-tensioned section, a horizontal section with bending areas at both ends, a bending portion, and a vertical section. The pre-tensioned section is engraved with gratings 1504 (WX-1 to WX-7), and the horizontal section, bending portion, and vertical section are engraved with gratings 1504 (WW-1 to WW-6). The beam-column node 2 area involved in this invention is a cast-in-place concrete structure. The concrete in the node area will be installed after reaching the designed height. After strength calculation, the steel strands and fiber optic composite strands 15 at the beam ends are tensioned a second time using the post-tensioning method. Correspondingly, the gratings 1504 in the fiber optic composite strands 15 are arranged in a targeted manner according to the pre-tensioning section, the secondary tensioning section, and the bending section. This facilitates targeted perception and feedback of the structure in stages and areas during construction and use, improving the efficiency and accuracy of monitoring. Furthermore, based on the recorded changes in prestress values ​​of the strands in each stage and area of ​​the fiber optic composite strands 15, the actual prestress loss values ​​of the precast prestressed beam 3 in different stages and areas under various load conditions can be calculated, providing a reference and basis for the subsequent optimized design of this type of component.

[0095] Specifically, in step S2, the calibration of the optical fiber composite twisted cable 15 includes:

[0096] S2-1. Record the wavelength of the fiber composite stranded wire 15 when it is not tensioned, as the initial wavelength;

[0097] S2-2, Tensile the fiber optic composite stranded wire to 5kN for pre-tensioning;

[0098] S2-3. Load the fiber optic composite stranded cable at 20KN increments, up to 80% of the cable's maximum load capacity. Keep the loading speed within 10KN / min. Hold each loading cycle for 5 minutes and record the corresponding wavelength.

[0099] S2-4. After recording the wavelength corresponding to the specified load, hold the load for 15 minutes and observe whether there are any abnormalities or even failures in the fiber optic grating signal transmission. After confirming that there are no errors, unload the load step by step to 0.

[0100] S2-5. Repeat steps S2-2 to S2-4 5 times and take the average value for calibration calculation.

[0101] Specifically, in step S3-1, the fiber optic composite stranded wire 15 is fixed at the designed position in the precast prestressed beam, and the fiber optic composite stranded wire 15 and the prestressed steel strand are tensioned synchronously. The data acquisition device automatically records the tension value of the pre-tensioned section of the fiber optic composite stranded wire 15 during the tensioning process. Tensioning is stopped after the design value is reached, and temporary anchoring is performed at both ends of the tensioning platform to prevent the prestress from decreasing. The tension values ​​of the pre-tensioned section of the fiber optic composite stranded wire 35 during the secondary tensioning and the pre-tensioned section of the bent and anchored fiber optic composite stranded wire 36 in this stage are recorded as F. 1-EX-i (i = 1, 2, 3, ..., 7), F 1-WX-i (i = 1, 2, 3, ..., 7).

[0102] Specifically, in step S3-2, the sensor includes: an embedded sensor and an external sensor.

[0103] The embedded sensors include: a reinforcement stress gauge 8, a strain gauge 9, and a joint gauge 10. During the fabrication of each component, these embedded sensors are cast into the concrete at key control sections such as the node center, beam-column interface, beam mid-span, column base, and column top.

[0104] The reinforcement stress gauge 8 is fixed to the stirrups, column reinforcements and energy-dissipating reinforcements at key locations of the reinforced concrete column, precast prestressed beam, beam-column joint, such as the beam end, column end, plastic hinge zone of the beam and column and joint area, so as to monitor the stress state of these reinforcements in real time.

[0105] The strain gauge 9 is placed in areas of large concrete deformation, such as beam ends, column ends, plastic hinge zones of beams and columns, and joint areas, in order to monitor the concrete strain at these key locations in real time.

[0106] The crack gauge 10 is placed at the junction of the precast prestressed beam and the beam-column joint, the plastic hinge zone between the precast prestressed beam and the reinforced concrete column, and at locations where diagonal cracks may appear at the beam-column joint, so as to monitor the crack width of the concrete in real time.

[0107] The external sensors include: a laser rangefinder 18, a temperature and humidity sensor 19, an anemometer 20, an inclinometer 21, and an accelerometer 22, and these external sensors are mounted on the surface of the structure.

[0108] The laser rangefinder 18 and the inclinometer 21 are fixed on the surface of the upper end of the column facing another column to collect the inclination degree of the column and the distance between columns in real time during the column assembly, positioning and use of the structure. The inter-story drift angle of the structure can also be calculated based on this.

[0109] The temperature and humidity sensor 19, the wind speed and direction meter 20, and the accelerometer 22 are fixed on the floor slab of the top floor of the structure. They are used to collect the temperature and humidity, wind speed and direction of the environment in which the structure is located, as well as the horizontal and vertical acceleration of the structure in the event of an earthquake or a vibration source nearby, so as to provide a basis for judging the damage of the structure under dynamic load.

[0110] Specifically, step S3-3 includes the following steps: After setting up the formwork for the precast prestressed beam, concrete pouring begins. During the pouring and curing process, the tension changes in the steel strands are continuously collected and recorded through the fiber optic composite stranded cable 15. The tension values ​​of the secondary tensioned fiber optic composite stranded cable 35 and the pre-tensioned section of the bent and anchored fiber optic composite stranded cable 36 in this stage are respectively recorded as F. 2-E-X (i i =1,2…,3,、F 2-WX-i (i = 1, 2, 3, ..., 7);

[0111] In steps S3-4, after curing to the design strength, tension is released. During the release process, the tension changes in the upper and lower steel strands within the beam are continuously collected and recorded through the fiber optic composite stranded cable 15. The tension values ​​of the secondary tensioning fiber optic composite stranded cable 35 and the pre-tensioned section of the bent anchoring fiber optic composite stranded cable 36 in this stage are recorded as F. 3-EX-i (i = 1, 2, 3, ..., 7), F 3-WX-i (i=1,2,3,…,7); After the tensioning is completed, the strain of the concrete in the upper and lower parts of the precast prestressed beam mid-span is continuously collected and recorded during the tensioning process.

[0112] Specifically, step S5 includes the following steps:

[0113] S5-1. After the tensioning is completed, the precast prestressed beams are hoisted to the warehouse for stacking. The tension values ​​of the pre-tensioned sections of the secondary tensioned fiber composite stranded wire 35 and the bent anchored fiber composite stranded wire 36 during the hoisting and stacking process are recorded as F. 4-EX-i (i = 1, 2, 3, ..., 7), F 4-WX-i (i=1,2,3,…,7); then transported to the construction site, hoisted there, and continuously recorded the tension values ​​of the pre-tensioned sections of the secondary tensioned fiber composite stranded cable 35 and the bent anchored fiber composite stranded cable 36, denoted as F respectively. 5-E-X (i i =1,2…,3,、F 5-WX-i (i = 1, 2, 3, ..., 7);

[0114] S5-2. After hoisting is completed, begin pouring the concrete for the post-construction portion of the beam-column joint. During pouring and curing, record the force value of the bent section of the anchoring steel strand as F. 1-WW-i (i = 1, 2, 3, ..., 6);

[0115] Specifically, in step S6, after the concrete of the post-cast portion of the beam-column joint reaches its design strength, tensioning begins on the post-tensioned section of the secondary tensioned prestressed steel strand. The prestress values ​​of the pre-tensioned and post-tensioned sections of the fiber-optic composite strand 15 during the tensioning process are denoted as F, respectively. 6-EX-i (i = 1, 2, 3, ..., 7), F 6-WX-i (i = 1, 2, 3, ..., 7), F 1-EH-i (i=1,2,3,…,10), and the strain of the concrete in the joint area during the post-tensioning process is collected and recorded.

[0116] Specifically, in step S7, after the structure is constructed, during the entire use of the structure, the acquisition device automatically acquires and records the prestress values ​​F of the pre-tensioned and post-tensioned sections of the fiber optic composite stranded cable 15. 7-EX-i (i = 1, 2, 3, ..., 7), F 7-WX-i (i = 1, 2, 3, ..., 7), F 2-EH-i (i = 1, 2, 3, ..., 10), and the force F of the bending segment. 2-WW-i (i=1,2,3,…,6); at the same time, strain gauges 9, reinforcement stress gauges 8, crack gauges 10, inclinometers 21, temperature and humidity sensors 19 are used to monitor and record data such as concrete strain, reinforcement stress, concrete crack width, structural tilt and temperature and humidity at the set locations in real time, and upload them to the cloud server in real time.

[0117] Specifically, in order to establish a complete real-time structural safety monitoring system, the sensors are integrated with an Internet of Things (IoT) architecture, cloud computing, seamless connection technology of local area networks or communication networks, and parallel intelligent processing technology of massive node data through supporting transmission equipment. The specific implementation process is as follows:

[0118] The signal is transmitted from the sensor to the intelligent sensor acquisition instrument 26 via signal line 38, and the signal is transmitted from the fiber optic composite twisted cable 15 to the multi-channel fiber optic strain gauge 23 via optical fiber cable. The multi-channel fiber optic strain gauge 23 and the intelligent sensor acquisition instrument 26 transmit the acquired data to the on-site monitoring room terminal 25 in real time and save it to the on-site database 24. At the same time, the data is transmitted to the cloud server 28 in real time via the data wireless transmission device 27, and then transmitted to the remote monitoring room terminal 30 and the remote database 31 via the network and switch 29. It can also be transmitted to the mobile terminal 33 in real time via the operator base station 32, providing maintenance personnel with multiple monitoring and management methods.

[0119] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for full-process monitoring of intelligent sensing precast prestressed concrete frame, the concrete frame structure including reinforced concrete columns, beam-column joints and precast prestressed beams, the precast prestressed beams containing multiple prestressed steel strands and fiber optic composite strands, the prestressed steel strands at the bottom of the beam containing at least one secondary tensioned fiber optic composite strand and one bent and anchored fiber optic composite strand, the portions of the prestressed steel strands and fiber optic composite strands in the beam body are all prestressed by the pre-tensioning method, the two ends of the prestressed steel strands and fiber optic composite strands extend from both ends of the precast prestressed beam, some of the extended portions are bent at 90° and anchored in the joint, the extended portions of the remaining portions are not bent but prestressed by the post-tensioning method to the beam-column joint; The whole-process monitoring method is characterized in that... Includes the following steps: S1. Design and manufacture fiber optic composite stranded cables; S2. Calibrate the fiber optic composite twisted cable to determine the sensing parameters of the internal optical fiber under different load conditions. S3. Prepare prestressed beams; S3-1. Fix and tension the prestressed steel strands and fiber optic composite strands. Distribute the prestressed steel strands and fiber optic composite strands at the upper and lower parts of the corresponding positions of the precast prestressed beam, and monitor and record the prestress value of the fiber optic composite strands. S3-2. Fix and calibrate each sensor used for monitoring, and lay the sensor and fiber optic composite twisted cable at the monitoring position to monitor the changes of each mechanical parameter in real time. S3-3, formwork erection, pouring concrete for beams and columns to prepare precast prestressed beams, and monitoring and recording the prestress value of fiber optic composite stranded wires; S3-4. Deform and release the prestressed beam, and continuously monitor and record the prestress value of the fiber optic composite stranded wire. S4. Bend the prestressed steel strands and optical fiber composite strands that extend from the bottom of the prestressed beam at 90°. S5. Transport and hoist precast prestressed beams and reinforced concrete columns, pour concrete for the post-cast portion of the beam-column joint, anchor the bent prestressed steel strands and fiber optic composite strands in the beam-column joint, and monitor and record the prestress value of the fiber optic composite strands. S6. After the cast-in-place concrete in the joint area reaches the design strength, the prestressed steel strands and fiber composite strands extending from the beam ends are post-tensioned using the post-tensioning method to apply prestress to the concrete in the beam-column joint area, and the prestress value of the fiber composite strands is monitored and recorded. S7. After the structure is constructed, during the structural use phase, monitor and record the changes in various mechanical parameters of the structure in real time. S8. Based on the parameter changes monitored and recorded in step S7, analyze and evaluate the internal force state of the structure and components, and determine whether the structure has been damaged. S9. When the changes in the internal forces of a component endanger the structural safety, the system will automatically issue an early warning and repair, reinforce, or replace the component; when the changes in the internal forces of a component are within a safe range, the structure does not require maintenance and can continue to be used. S10. After the structure reaches the end of its service life, the structure will be dismantled, and intelligent monitoring will end.

2. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S1, gratings are fabricated at corresponding positions of the pre-tensioned section, post-tensioned section, and bending section on the optical fiber inside the optical fiber composite stranded cable, and the gratings are marked and numbered.

3. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S2, the calibration of the fiber optic composite twisted cable includes: S2-1. Record the wavelength of the fiber optic composite stranded wire when it is not tensioned, and use it as the initial wavelength; S2-2, Tension the fiber optic composite stranded wire to 5kN for pre-tightening; S2-3. Load the fiber optic composite stranded wire at 20KN increments, up to 80% of its ultimate load capacity. Keep the loading speed within 10KN / min. Hold each loading step for 5 minutes and record the corresponding wavelength. S2-4. After recording the wavelength corresponding to the specified load, hold the load for 15 minutes and observe whether there are any abnormalities or even failures in the fiber Bragg grating signal transmission. After confirming that there are no errors, gradually unload the load to 0. S2-5. Repeat steps S2-2 to S2-4 5 times and take the average value for calibration calculation.

4. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S3-1, the fiber composite stranded wire is fixed at the designed position in the precast prestressed beam, and the fiber composite stranded wire and the prestressed steel strand are tensioned synchronously. The acquisition device automatically records the tension value of the first tensioned section of the fiber composite stranded wire during the tensioning process. After the design value is reached, the tensioning is stopped, and the two ends of the tensioning platform are temporarily anchored to prevent the prestress from decreasing. The tension values ​​of the second tensioning of the fiber composite stranded wire and the bending and anchoring of the first tensioned section of the fiber composite stranded wire are recorded during this stage.

5. The intelligent sensing method for monitoring the entire process of precast prestressed concrete frames according to claim 1, characterized in that: In step S3-2, the sensor includes: Embedded sensors include: reinforcement stress gauges, strain gauges and joint gauges. During the fabrication of each component, these embedded sensors are cast into the concrete at key control sections such as the center of the node, the beam-column interface, the mid-span of the beam, the column base and the column top. The reinforcement stress gauge is fixed to the stirrups, column reinforcement, and energy-dissipating reinforcement at key locations of the reinforced concrete column, precast prestressed beam, and beam-column joint. The strain gauges are placed in areas of large concrete deformation, such as reinforced concrete columns, precast prestressed beams, and beam-column joints. The crack gauge is placed at the junction of the precast prestressed beam and the beam-column joint, the plastic hinge zone between the precast prestressed beam and the reinforced concrete column, and at locations where diagonal cracks may appear at the beam-column joint.

6. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S3-2, the sensor includes: External sensors, including laser rangefinders, temperature and humidity sensors, anemometers, inclinometers, and accelerometers, are mounted on the surface of the structure. The laser rangefinder and the inclinometer are fixed to the surface of the upper end of the column facing another column; The temperature and humidity sensor, anemometer, and accelerometer are fixed to the floor slab of the top floor of the structure.

7. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S3-3, after the formwork of the precast prestressed beam is set up, the concrete is poured. During the pouring and curing process, the tension change in the steel strand is continuously collected and recorded through the fiber optic composite strand. The tension values ​​of the secondary tensioning fiber optic composite strand and the pre-tensioned section of the bent anchoring fiber optic composite strand are recorded at this stage. In steps S3-4, after curing to the design strength, tension is released. During the release process, the tension changes in the upper and lower steel strands in the beam are continuously collected and recorded through fiber optic composite strands. The tension values ​​of the pre-tensioned sections of the secondary tensioned fiber optic composite strands and the bent anchored fiber optic composite strands are recorded. After the release is completed, the strain of the concrete in the upper and lower mid-span of the precast prestressed beam is continuously collected and recorded during the release process.

8. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: Step S5 includes the following steps: S5-1. After the tensioning is completed, the precast prestressed beams are hoisted to the warehouse for stacking, and then transported to the construction site for hoisting. The tension values ​​of the pre-tensioned section of the secondary tensioned fiber composite stranded wire and the bent anchored fiber composite stranded wire are continuously recorded. S5-2. After hoisting is completed, start pouring concrete for the post-cast portion of the beam-column joint. Record the force value of the bent section of the bending anchor steel strand during the pouring and curing process.

9. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: In step S7, the acquisition device automatically acquires and records the prestress values ​​of the pre-tensioned and post-tensioned sections of the fiber optic composite stranded cable, as well as the force value of the bending section. At the same time, each sensor performs real-time monitoring and recording, and uploads the data to the cloud server in real time.

10. The method for monitoring the entire process of intelligent sensing precast prestressed concrete frames according to claim 1, characterized in that: The sensor is integrated with the Internet of Things (IoT) architecture, cloud computing, local area network (LAN) or communication network, and massive node data parallel intelligent processing technology through supporting transmission equipment to establish a complete real-time structural safety monitoring system.

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