Prestressed construction control method based on weak fiber Bragg grating intelligent steel strand

Abstract

The present invention discloses a prestressed construction control method based on weak fiber grating smart steel strand, comprising the following steps: S101, preparing weak fiber grating smart steel strand; S102, installing the weak fiber grating smart steel strand into one of the prestressed pipes; S103, tensioning the weak fiber grating smart steel strand, collecting strain data; S104, calculating the measured instantaneous loss value of prestress according to the strain data; S105, correcting the optimized tension control force value; S106, grouting the prestressed pipe, collecting the temperature of each point along the weak fiber grating smart steel strand; S107, judging the position of the grouting not dense in the prestressed pipe under the current grouting process; S108, correcting the optimized grouting process; S109, according to the optimized tension control force value and grouting process, prestressing construction of the prestressed steel strand in the remaining prestressed pipes is carried out. The present invention realizes the precise control of the prestressed construction of concrete structures, and effectively improves the control level of prestressed construction.

Description

Technical Field

[0001] The present invention relates to the field of prestressed construction, and more specifically, to a prestressed construction control method based on weak fiber grating intelligent steel strands. Background Art

[0002] Prestressing technology works by applying effective prestress to the structure. The amount of effective prestress is directly related to the safety and functionality of the structure. At present, prestressing technology generally constructs prestress by inserting steel strands into concrete, then tensioning them to a certain stress level and pouring cement slurry to protect the steel strands. The amount of prestressing applied is mainly calculated and determined by estimating the instantaneous and long-term loss values ​​of prestress. Among them, the instantaneous prestress loss is mainly related to the site conditions of the structure, which is greatly affected by the construction conditions and is difficult to estimate, resulting in low control accuracy of prestressed construction of concrete structures. The durability of prestressed steel strands is mainly controlled by the density of grouting. After the prestressing is completed, the cement slurry will be poured into the pipeline to seal it so that the cement slurry can fully wrap the steel strands to prevent them from rusting. Affected by the grouting process, insufficient grouting density will also lead to a decrease in the control level of prestressed construction. Therefore, in order to solve the problems of inaccurate tension control force, poor reliability, and loose grouting in the existing prestressed concrete structure construction, it is necessary to propose a prestressed construction control method based on weak fiber grating intelligent steel strands, which can achieve precise control of prestressed construction from two aspects: accuracy of prestressing application and optimization of prestressed grouting process, and improve the level of prestressed construction control. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, a prestressed construction control method based on weak fiber Bragg grating intelligent steel strand is provided, which is used for prestressed construction of concrete structure, wherein a plurality of prestressed pipes are pre-buried in the concrete structure, and the prestressed construction control method comprises the following steps:

[0005] S101, preparing a weak fiber Bragg grating smart steel strand, wherein the weak fiber Bragg grating smart steel strand has a fiber Bragg grating strain sensing optical fiber and a fiber Bragg grating temperature sensing optical fiber built therein;

[0006] S102, installing the weak fiber Bragg grating intelligent steel strand into one of the prestressed pipes;

[0007] S103, tensioning one end of the weak fiber Bragg grating smart steel strand using a tensioning jack, and collecting strain data monitored by the fiber Bragg grating strain sensing optical fiber at the other end of the weak fiber Bragg grating smart steel strand;

[0008] S104, calculating the measured instantaneous loss value of prestress according to the strain data;

[0009] S105, correcting the tension control force value according to the measured instantaneous loss value of the prestress to obtain an optimized tension control force value;

[0010] S106, grouting the prestressed pipe where the weak fiber Bragg grating smart steel strand is located, and simultaneously collecting the temperature of each point along the weak fiber Bragg grating smart steel strand monitored by the fiber Bragg grating temperature sensing optical fiber;

[0011] S107, judging the location of the grouting not being dense in the prestressed pipe under the current grouting process according to the relationship between the temperature and the grouting density;

[0012] S108, according to the position where the grouting is not dense in the prestressed pipe, changing the grouting speed and the grouting method to form an optimized grouting process;

[0013] S109. Perform prestressing construction of the remaining prestressed steel strands in the prestressed pipe according to the optimized tensioning control force value and grouting process.

[0014] Preferably, the weak fiber Bragg grating intelligent steel strand is formed by twisting a special-shaped steel wire and a plurality of side wires, and the outer periphery of the special-shaped steel wire is symmetrically provided with two through grooves about its center, and the fiber Bragg grating strain sensing optical fiber and the fiber Bragg grating temperature sensing optical fiber are respectively arranged in the two through grooves.

[0015] Preferably, the spacing between two adjacent gratings on the fiber grating strain sensing fiber and the fiber grating temperature sensing fiber is 0.5-50 meters, and the reflectivity of each grating is not greater than 1%.

[0016] Preferably, one end of the weak fiber Bragg grating intelligent steel strand is connected to a demodulation device via an optical fiber lead, and the demodulation device is connected to a data processing device; the demodulation device is used to collect and store the wavelength data of each grating on the fiber Bragg grating strain sensing fiber and the fiber Bragg grating temperature sensing fiber.

[0017] Preferably, the data processing device calculates the measured instantaneous loss value of the prestress according to the following formula:

[0018] σ1=σ con -σ2-σ FBG

[0019]

[0020] In the formula, σ con is the tension control force value; σ1 is the measured instantaneous loss value of prestress; σ2 is the long-term instantaneous value of prestress, which is a known parameter; σ FBGrepresents the average measured effective stress value of prestressing; fai is the initial value of the wavelength of each grating on the fiber Bragg grating strain sensing fiber; fbi is the measured value of the wavelength of each grating on the fiber Bragg grating strain sensing fiber; tai is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; tbi is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; K fi It is the ratio of the load borne by the weak fiber Bragg grating smart steel strand to the wavelength change value of each grating on the fiber Bragg grating strain sensing optical fiber; i represents the grating sequence number, from 1 to n; A is the effective cross-sectional area of ​​the weak fiber Bragg grating smart steel strand.

[0021] Preferably, the data processing device calculates the temperature of each point along the weak fiber Bragg grating smart steel strand according to the following formula:

[0022] T j =(λ tbj -λ taj )×K tj

[0023] Where, T j is the temperature of the point on the weak fiber Bragg grating intelligent steel strand corresponding to the grating with serial number j on the fiber Bragg grating temperature sensing fiber; tbj is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; taj K is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; tj It is the ratio of the temperature of the weak fiber Bragg grating intelligent steel strand 3 to the wavelength change value of each grating on the fiber Bragg grating temperature sensing optical fiber 34; j represents the serial number of each grating on the fiber Bragg grating temperature sensing optical fiber 34, from 1 to m.

[0024] Preferably, in step 107, according to the temperature of each point along the weak fiber Bragg grating smart steel strand, when the temperature value measured by a certain grating on the fiber Bragg grating temperature sensing optical fiber is not higher than the set temperature difference value, it is judged that the grouting of the grating position area is not dense.

[0025] Preferably, the temperature difference is calculated as follows:

[0026] ΔT=(T j+1 +T j-1 ) / 2×(1-θ)

[0027] Where, T j+1 and T j-1 is the temperature value measured by the gratings on both sides of grating j; θ is the temperature difference coefficient, and its value is determined by the selected grouting material, the diameter of the grouting bellows and the grouting environment temperature.

[0028] Preferably, in step 108, according to the obtained loose grouting position, the grouting process is adjusted in sequence from three aspects: grouting speed, grouting method, and initial setting time of the grouting material, until the temperature value measured by the corresponding grating is higher than the set temperature difference value, that is, the grouting is considered to be dense, and the grouting process at this time is determined as the grouting process for the prestressed construction of the prestressed bundles of the steel strands in the remaining prestressed pipes.

[0029] The present invention has at least the following beneficial effects:

[0030] The prestressed construction control method based on weak fiber grating intelligent steel strand provided by the present invention optimizes the tensioning control force and the grouting process through the measured instantaneous loss value of prestress under the current tensioning process of the weak fiber grating intelligent steel strand and the position of loose grouting in the prestressed pipe under the current grouting process, and then uses the optimized tensioning control force and grouting process to guide the prestressed construction of the remaining ordinary steel strand prestressed bundles, thereby achieving precise control of the overall prestressed construction of the concrete structure and effectively improving the level of prestressed construction control.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Flow chart of the prestressed construction control method based on weak fiber Bragg grating intelligent steel strand according to the present invention

[0033] Figure 2 This is a schematic diagram of the location of the weak fiber Bragg grating intelligent steel strand of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the weak fiber Bragg grating intelligent steel stranded wire of the present invention;

[0035] Figure 4 It is a structural schematic diagram of the special-shaped steel wire of the present invention; DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0037] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] like Figure 1 As shown, the present invention provides a prestressed construction control method based on weak fiber Bragg grating intelligent steel strand, which is used for prestressed construction of concrete structure, wherein a plurality of prestressed pipes are pre-buried in the concrete structure, and the prestressed construction control method comprises the following steps:

[0039] S101, preparing a weak fiber Bragg grating smart steel strand 3, wherein the weak fiber Bragg grating smart steel strand 3 has a fiber Bragg grating strain sensing optical fiber 33 and a fiber Bragg grating temperature sensing optical fiber 34 built therein;

[0040] S102, installing the weak fiber Bragg grating smart steel strand 3 into one of the prestressed pipes;

[0041] S103, tensioning one end of the weak fiber Bragg grating smart steel strand 3 using a tensioning jack, and collecting strain data monitored by the fiber Bragg grating strain sensing optical fiber 33 at the other end of the weak fiber Bragg grating smart steel strand 3;

[0042] S104, calculating the measured instantaneous loss value of prestress according to the strain data;

[0043] S105, correcting the tension control force value according to the measured instantaneous loss value of the prestress to obtain an optimized tension control force value;

[0044] S106, grouting the prestressed pipe where the weak fiber Bragg grating smart steel strand 3 is located, and at the same time collecting the temperature of each point along the weak fiber Bragg grating smart steel strand 3 monitored by the fiber Bragg grating temperature sensing optical fiber 34;

[0045] S107, judging the location of the grouting not being dense in the prestressed pipe under the current grouting process according to the relationship between the temperature and the grouting density;

[0046] S108. According to the location where the grouting is not dense in the prestressed pipe, the grouting speed and the grouting method are changed to form an optimized grouting process.

[0047] S109. Perform prestressing construction of the remaining prestressed steel strands in the prestressed pipe according to the optimized tensioning control force value and grouting process.

[0048] In this technical solution, the weak fiber Bragg grating intelligent steel strand 3 with the built-in fiber Bragg grating strain sensing fiber 33 and the fiber Bragg grating temperature sensing fiber 44 is inserted into the concrete structure 6. On the one hand, the weak fiber Bragg grating intelligent steel strand 3 is tensioned by the tensioning jack 1, and the data monitored by the fiber Bragg grating strain sensing fiber 33 is collected and analyzed to obtain the measured instantaneous loss value of the current process prestressing, thereby correcting the tensioning control force; on the other hand, in the process of grouting into the prestressed pipe, the data monitored by the fiber Bragg grating temperature sensing fiber 34 is collected and analyzed to obtain the position of the grouting in the prestressed pipe under the current grouting process, thereby guiding the optimization of the grouting process. Finally, the optimized tensioning control force and grouting process are used to guide the prestressing construction of the remaining ordinary steel strand prestressing bundles, thereby realizing the precise control of the overall prestressing construction of the concrete structure 6, effectively improving the control level of the prestressing construction.

[0049] First, in step 101, the weak fiber Bragg grating intelligent steel strand is prepared, specifically, as follows: Figure 3 and Figure 4 As shown, the weak fiber Bragg grating intelligent steel strand 3 is formed by a special-shaped steel wire 32 and a plurality of side wires 31, and the outer periphery of the special-shaped steel wire 31 is symmetrically provided with two through grooves about its center, and the two through grooves are provided with the fiber Bragg grating strain sensing optical fiber 33 and the fiber Bragg grating temperature sensing optical fiber 34. The two through grooves are arranged along the length direction of the special-shaped steel wire 32. In this embodiment, the diameter of the weak fiber Bragg grating intelligent steel strand 3 is 15.2mm, the diameter of the special-shaped steel wire 32 is 5.2mm, the pitch of the side wire 31 is 180-250mm, and the diameters of the fiber Bragg grating temperature sensing optical fiber 34 and the fiber Bragg grating strain sensing optical fiber 33 are both 0.25mm. The fiber Bragg grating strain sensing optical fiber 33 is tightly fitted in one of the through grooves, and the fiber Bragg grating temperature sensing optical fiber 34 is freely placed in the other through groove.

[0050] The fiber Bragg grating strain sensing fiber 33 and the fiber Bragg grating temperature sensing fiber 34 are both arrayed fiber Bragg grating sensors, and multiple gratings are engraved on the sensing fibers of the two at intervals. Furthermore, the spacing between two adjacent gratings on the fiber Bragg grating strain sensing fiber 33 and the fiber Bragg grating temperature sensing fiber 34 is 0.5 to 50 meters. In actual use, the typical spacing between two adjacent gratings is 1 meter, and other spacing specifications can also be selected as needed; the reflectivity of each grating is not greater than 1%.

[0051] In step S102, the weak fiber Bragg grating intelligent steel strand 3 is installed, referring to Figure 2 , the weak fiber Bragg grating intelligent steel strand 3 is passed through the prestressed pipe of the concrete structure 6, one end of the weak fiber Bragg grating intelligent steel strand 3 passes through the working anchor 2 to leave a certain length for easy tensioning, and the other end passes through the working anchor 2 on the other side of the concrete structure 6. It should be noted that, Figure 2 Marks 4 and 5 are both common prestressed steel strand bundles, which are used as examples here, and are not intended to limit the number of prestressed steel strand bundles. Specifically, one end of the weak fiber Bragg grating smart steel strand 3 is connected to a demodulation device 8 through an optical fiber lead 7, and the demodulation device 8 is connected to a data processing device 9; the demodulation device 8 is used to collect and store the wavelength data of each grating on the fiber Bragg grating strain sensing fiber 33 and the fiber Bragg grating temperature sensing fiber 34.

[0052] In step S103, one end of the weak fiber Bragg grating smart steel strand 3 is tensioned by using the tensioning jack 1, and the wavelength data of each grating on the fiber Bragg grating strain sensing optical fiber 33 is collected at the other end by using the demodulation device 8.

[0053] In step S104, the data processing device 9 calculates the measured instantaneous loss value of the prestress according to the following formula:

[0054] σ1=σ con -σ2-σ FBG (1)

[0055]

[0056] In formula (1) and formula (2), σ con is the tension control force value; σ1 is the measured instantaneous loss value of prestress; σ2 is the long-term instantaneous value of prestress, which is given by the design unit and is a known parameter; σ FBG represents the average measured effective stress value of prestressing; fai is the initial value of the wavelength of each grating on the fiber Bragg grating strain sensing optical fiber 33; fbi is the measured value of the wavelength of each grating on the fiber Bragg grating strain sensing optical fiber 33; tai is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber 34; tbi K is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing optical fiber 34; fi It is the ratio of the load borne by the weak fiber Bragg grating smart steel strand 3 to the wavelength change value of each grating on the fiber Bragg grating strain sensing optical fiber 33; i represents the grating sequence number, from 1 to n; A is the effective cross-sectional area of ​​the weak fiber Bragg grating smart steel strand 3.

[0057] In step S105, the tension control force value σ is adjusted according to the measured instantaneous loss value σ1 of the prestress.con Correction is performed to obtain the optimized tension control force value σ c ; Specifically, σ c Calculate as follows:

[0058] σ c =σ con +σ1-σ 11 +h (3)

[0059] In formula (3), σ 11 is the theoretical instantaneous loss value of prestress, which is given by the design unit; h is the supplementary coefficient for the instantaneous loss of prestress after improving the tensioning control force, which is an empirical value.

[0060] In step S106, grouting is performed on the prestressed pipe where the weak fiber Bragg grating intelligent steel strand 3 is located, and at the same time, the wavelength data of each grating on the fiber Bragg grating temperature sensing optical fiber 34 is collected by the demodulation device 8;

[0061] Then the data processing device 9 calculates the temperature of each point along the weak fiber Bragg grating intelligent steel strand 3 according to the following formula:

[0062] T j =(λ tbj -λ taj )×K tj (4)

[0063] In formula (4), T j is the temperature of the point on the weak fiber Bragg grating intelligent steel strand 3 corresponding to the grating with the serial number j on the fiber Bragg grating temperature sensing optical fiber 34, λ tbj is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing optical fiber 34; taj K is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber 34; tj It is the ratio of the temperature of the weak fiber Bragg grating intelligent steel strand 3 to the wavelength change value of each grating on the fiber Bragg grating temperature sensing optical fiber 34; j represents the serial number of each grating on the fiber Bragg grating temperature sensing optical fiber 34, from 1 to m.

[0064] In step S107, according to the temperature of each point along the weak fiber Bragg grating smart strand 3, when the temperature value measured by a certain grating on the fiber Bragg grating temperature sensing optical fiber 34 is not higher than the set temperature difference value ΔT, it is determined that the grouting at the grating position area is not dense.

[0065] Specifically, the temperature difference value is calculated as follows:

[0066] ΔT=(T j+1 +T j-1 ) / 2×(1-θ) (5)

[0067] In formula (5), T j+1 and T j-1 is the temperature value measured by the gratings on both sides of grating j; θ is the temperature difference coefficient, which is determined by the selected grouting material, the diameter of the grouting bellows and the grouting environment temperature, and can be taken as 3%. That is, when T j When ≤ΔT, there is loose grouting in the grating j position area.

[0068] In step 108, according to the obtained loose grouting position, the grouting process is adjusted in turn from three aspects: grouting speed, grouting method, and initial setting time of the grouting material, until the temperature value measured by the corresponding grating j is higher than the set temperature difference value ΔT, that is, the grouting in the grating j position area is considered to be dense, and the grouting process at this time is determined as the grouting process for the prestressed construction of the prestressed steel strands in the remaining prestressed pipes.

[0069] Finally, in step 109, the prestressing construction of the steel strand prestressing bundles in the remaining prestressed pipes is carried out according to the optimized tensioning control force value and grouting process, so as to realize the precise control of the dual-item prestressing construction of the concrete structure.

[0070] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A prestressed construction control method based on weak fiber Bragg grating intelligent steel strand, used for prestressed construction of concrete structure, wherein a plurality of prestressed pipes are pre-buried in the concrete structure, characterized in that: The prestressed construction control method comprises the following steps: S101, preparing a weak fiber Bragg grating smart steel strand, wherein the weak fiber Bragg grating smart steel strand has a fiber Bragg grating strain sensing optical fiber and a fiber Bragg grating temperature sensing optical fiber built therein; S102, installing the weak fiber Bragg grating intelligent steel strand into one of the prestressed pipes; S103, tensioning one end of the weak fiber Bragg grating smart steel strand using a tensioning jack, and collecting strain data monitored by the fiber Bragg grating strain sensing optical fiber at the other end of the weak fiber Bragg grating smart steel strand; S104, calculating the measured instantaneous loss value of prestress according to the strain data; S105, correcting the tension control force value according to the measured instantaneous loss value of the prestress to obtain an optimized tension control force value; S106, grouting the prestressed pipe where the weak fiber Bragg grating smart steel strand is located, and simultaneously collecting the temperature of each point along the weak fiber Bragg grating smart steel strand monitored by the fiber Bragg grating temperature sensing optical fiber; S107, judging the location of the grouting not being dense in the prestressed pipe under the current grouting process according to the relationship between the temperature and the grouting density; S108, according to the position where the grouting is not dense in the prestressed pipe, changing the grouting speed and the grouting method to form an optimized grouting process; S109, performing prestressing construction of the prestressed strands of the remaining prestressed pipes according to the optimized tensioning control force value and grouting process; One end of the weak fiber Bragg grating intelligent steel strand is connected to a demodulation device through an optical fiber lead, and the demodulation device is connected to a data processing device; the demodulation device is used to collect and store the wavelength data of each grating on the fiber Bragg grating strain sensing fiber and the fiber Bragg grating temperature sensing fiber; The data processing device calculates the temperature of each point along the weak fiber Bragg grating intelligent steel strand according to the following formula: T j =(λ) tbj- l taj )× K tj Where, T j is the temperature of the point on the weak fiber Bragg grating intelligent steel strand corresponding to the grating with serial number j on the fiber Bragg grating temperature sensing fiber; tbj is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; taj is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; K tj is the ratio of the temperature of the weak fiber Bragg grating intelligent steel strand to the wavelength change value of each grating on the fiber Bragg grating temperature sensing optical fiber; j represents the serial number of each grating on the fiber Bragg grating temperature sensing optical fiber, from 1 to m.

2. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 1 is characterized in that: The weak fiber Bragg grating intelligent steel strand is formed by twisting a special-shaped steel wire and multiple side wires. The outer periphery of the special-shaped steel wire is symmetrically provided with two through grooves about its center. The fiber Bragg grating strain sensing optical fiber and the fiber Bragg grating temperature sensing optical fiber are respectively arranged in the two through grooves.

3. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 2 is characterized in that: The spacing between two adjacent gratings on the fiber grating strain sensing fiber and the fiber grating temperature sensing fiber is 0.5-50 meters, and the reflectivity of each grating is not greater than 1%.

4. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 1 is characterized in that: The data processing device calculates the measured instantaneous loss value of the prestress according to the following formula: σ1 =σ con -s2-s FBG In the formula, σ con is the tension control force value; σ1 is the measured instantaneous loss value of prestress; σ2 is the long-term instantaneous value of prestress, which is a known parameter; σ FBG represents the average measured effective stress value of prestressing; fai is the initial value of the wavelength of each grating on the fiber Bragg grating strain sensing fiber; fbi is the measured value of the wavelength of each grating on the fiber Bragg grating strain sensing fiber; tai is the initial value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; tbi is the measured value of the wavelength of each grating on the fiber Bragg grating temperature sensing fiber; K fi It is the ratio of the load borne by the weak fiber Bragg grating smart steel strand to the wavelength change value of each grating on the fiber Bragg grating strain sensing optical fiber; i represents the grating sequence number, from 1 to n; A is the effective cross-sectional area of ​​the weak fiber Bragg grating smart steel strand.

5. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 1 is characterized in that: In step 107, according to the temperature of each point along the weak fiber Bragg grating intelligent steel strand, when the temperature value measured by a certain grating on the fiber Bragg grating temperature sensing optical fiber is not higher than the set temperature difference value, it is determined that the grouting at the grating position area is not dense.

6. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 5, characterized in that: The temperature difference value is calculated as follows: ∆T=(T j+1 +T j-1 ) / 2×(1-θ) Where, T j+1 and T j-1 is the temperature value measured by the gratings on both sides of grating j; θ is the temperature difference coefficient, and its value is determined by the selected grouting material, the diameter of the grouting bellows and the grouting environment temperature.

7. The prestressed construction control method based on weak fiber Bragg grating intelligent steel strand as claimed in claim 5, characterized in that: In step 108, according to the obtained loose grouting position, the grouting process is adjusted in turn from three aspects: grouting speed, grouting method, and initial setting time of the grouting material, until the temperature value measured by the corresponding grating is higher than the set temperature difference value, that is, the grouting is considered to be dense, and the grouting process at this time is determined as the grouting process for the prestressed construction of the prestressed steel strands in the remaining prestressed pipes.

Images