Construction method of high-altitude large-span arc-shaped prestressed beam

Abstract

The invention discloses a high-altitude large-span arc-shaped prestressed beam construction method, and particularly relates to the technical field of prestressed beam construction, which comprises the following steps: S1, carrying out dip angle monitoring modeling to generate a pre-arch coordinate; s2, scanning pipeline coordinates, comparing the pipeline coordinates with the BIM, and building a deviation matrix; s3, performing over-limit identification and segmented pouring planning; s4, curvature friction collection is carried out, and compensation tension is calculated; and S5, a final tensioning generation record is generated after the extension amount checking is completed. A tilt angle sensor is arranged to monitor deformation of a supporting system, a three-dimensional deformation model is constructed in combination with a wind load to generate pre-arch coordinates, a total station scans pipeline coordinates and compares the pipeline coordinates with a BIM theoretical value to establish an axial deviation matrix, an overrun section is recognized, pouring units are divided, the construction time sequence is optimized, and deformation accumulation is reduced. The curvature and friction coefficient of the pipeline are collected in real time to construct a friction compensation model, graded tension control is combined with extension threshold judgment, anchoring retraction is dynamically monitored to generate a final tension record, a closed-loop control system is formed, and the forming precision and stress stability of a large-curvature component are improved.

Description

Technical Field

[0001] The invention relates to the technical field of prestressed beam construction, and in particular to a construction method of a high-altitude large-span curved prestressed beam. Background Art

[0002] The field of prestressed construction technology encompasses the prestressed tendon tensioning process, anchor system installation, and stress control in concrete structural engineering. Its core focus is improving structural performance through prestressing, involving key technical aspects such as strand positioning, tensioning equipment configuration, and stress loss compensation. This field focuses on load transfer mechanisms under high-altitude working conditions, precision control of forming components with large curvature, and methods for maintaining long-term stress. It encompasses specialized technical content such as formwork support system design, spatial positioning measurement of prestressed tendons, and sequential control of segmented tensioning.

[0003] The construction method for high-altitude, large-span curved prestressed beams uses three-dimensional coordinate positioning technology to establish a spatial control network, achieves curvature control through segmented assembly of curved formwork, applies stress using multi-directional prestressing synchronous tensioning equipment, and dynamically adjusts based on data feedback from stress monitoring devices. This method specifically includes the construction of an aerial work platform, three-dimensional layout and positioning of prestressed tendons, implementation of a segmented casting process, and strengthening of tensioning end nodes. It also employs a graded loading method to balance structural deformation and uses computer simulation technology to optimize tensioning sequence parameters.

[0004] Existing support system deformation prediction relies on static load models, failing to consider the coupling effects of dynamic wind loads and concrete rheology. This results in delayed pre-camber compensation and excessive curvature deviations in formed components. Prestressed pipe positioning relies on manual lofting and discrete spot checks, lacking real-time comparison of full-section 3D coordinates with the BIM model. This creates blind spots in identifying over-limit sections. The segmented pouring sequence relies on empirical divisions, failing to incorporate a deviation matrix for quantitative analysis of stiffness distribution. Construction sequence parameters are rigidified, which can easily lead to localized stress concentrations. Prestressing control force calculations use a fixed friction coefficient, ignoring changes in pipe curvature and time-varying friction losses. Prestress distribution is uneven in sections with large curvature, leading to significant effective stress decay at the anchor end. Final tensioning verification is based on single elongation measurements, lacking a mechanism for graded loading and dynamic deviation judgment, resulting in insufficient control over long-term stress relaxation. The existing technology's discrete operations and static parameter models limit construction accuracy, increase the frequency of adjustments required for aerial work, and increase construction time and costs. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for constructing high-altitude, large-span curved prestressed beams, which can effectively solve the problems in the above-mentioned background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for constructing a high-altitude, large-span curved prestressed beam comprises the following steps:

[0008] S1: Deformation prediction of high-altitude support system and template pre-adjustment: High-precision inclination sensors are deployed at key nodes of the high-altitude support system to obtain posture data. A three-dimensional deformation model is constructed by combining the curvature radius of the arc template with the dynamic wind load spectrum. The dynamic deformation of the support system is calculated and superimposed with the design curvature to generate the pre-camber compensation coordinates of the arc template.

[0009] S2: Prestressed pipe spatial positioning verification: Based on the pre-camber compensation coordinates of the arc template, the three-dimensional coordinates of the prestressed pipe are scanned by a total station and compared with the theoretical values of the BIM design model. The axial deviation is calculated to generate the prestressed pipe spatial deviation matrix;

[0010] S3: Segmented pouring sequence planning: calling the prestressed pipe spatial deviation matrix to identify the over-limit section according to the GB allowable deviation, dividing the pouring units to generate a segmented pouring sequence plan;

[0011] S4: Calculation of tension control force in large curvature sections. Based on the segmented pouring sequence plan, real-time collection of pipe curvature and time-varying friction coefficient is performed to calculate additional tension force and generate curvature-compensated tension control force data.

[0012] S5: Review the elongation during the tensioning process. Measure the elongation based on the curvature compensation tensioning control force data and perform standard threshold judgment to complete the graded final tensioning and generate the final tensioning stress confirmation record.

[0013] Preferably, the pre-arch compensation coordinates of the arc formwork include the X / Y / Z compensation coordinates of the support point, the pre-arch adjustment amount, and the wind load deformation correction coefficient; the prestressed pipe spatial deviation matrix specifically includes the X / Y / Z deviation value of each measuring point, the deviation vector synthesis angle, and the over-limit section code; the segmented casting sequence plan includes the casting unit three-dimensional grid code, unit construction timing parameters, and joint processing technical indicators; the curvature compensation tensioning control force data includes the graded tensioning force setting value, friction compensation coefficient, and load-holding and stabilization time; the final tensioning stress confirmation record specifically refers to the measured stress value, theoretical deviation rate, and acceptance status identification code.

[0014] Preferably, the S1 step includes:

[0015] An inclination sensor is placed on the top of the vertical pole to obtain the inclination data and initial coordinates of each node of the support system. Combined with the curvature radius of the arc template and the wind load spectrum parameters, a three-dimensional load model is constructed to generate a support system posture data set.

[0016] The elastic modulus and creep coefficient of concrete rheological parameters are used to calculate the deformation displacement under the coupling of wind load and concrete deadweight based on the support system posture data set, and generate dynamic deformation trajectory parameters.

[0017] The dynamic deformation trajectory parameters and the designed curvature coordinates are vector-superimposed, the deformation components are decomposed along the X / Y / Z axes, the template control point coordinates are adjusted according to the curvature correction formula, and the arc template pre-camber compensation coordinates are generated.

[0018] Preferably, the S2 step includes:

[0019] After installing the template based on the pre-camber compensation coordinates of the arc template, use a total station to scan the X / Y / Z coordinates of each measuring point on the prestressed pipe, extract the theoretical coordinates of the corresponding measuring points in the BIM design model, and generate a table of measured-theoretical coordinates for the pipe.

[0020] Call the pipeline measured-theoretical coordinate alignment table, calculate the difference between the X / Y / Z axial measured value and the theoretical value at each measuring point, take the absolute value operation, and generate the axial deviation absolute value table;

[0021] The deviation values of each measuring point in the axial deviation absolute value table are classified and summarized according to the X / Y / Z axis, and a three-dimensional matrix structure is constructed. The data are arranged and stored according to the measuring point number to generate the prestressed pipe spatial deviation matrix.

[0022] Preferably, the S3 step includes:

[0023] Call the prestressed pipe spatial deviation matrix, compare the absolute value of the deviation with the threshold value according to the X / Y / Z axial allowable deviation threshold in the GB specification, mark the exceeding measurement point number, and generate the exceeding section code table;

[0024] Based on the over-limit section code table, the distance between adjacent over-limit measuring points and the average deviation are calculated, the areas are arranged in descending order by deviation, the stiffness weakness levels are divided, and a stiffness weakness area distribution map is generated;

[0025] According to the distribution map of weak stiffness areas, the construction sequence is arranged according to the principle of priority for low stiffness areas. The beam body is divided into continuous casting sections and assigned unique codes to generate a segmented casting sequence plan.

[0026] Preferably, the S4 step includes:

[0027] Obtain the concrete strength monitoring value of each pouring section according to the segmented pouring sequence plan, measure the curvature radius of each measuring point of the prestressed pipe, and generate the pipe curvature distribution map according to the distance between the measuring points;

[0028] The measured values of the friction coefficient of the steel strand at different tensioning stages are collected, the changes in the friction coefficient are recorded in time series, and the relationship curve between the friction coefficient and the tensioning time is fitted to generate a time-varying friction loss curve;

[0029] The pipeline curvature distribution map and time-varying friction loss curve are called up, combined with the design value of anchor retraction, to calculate the additional tension compensation value of each measuring point, distribute the tension control force according to the curvature weight, and generate curvature compensated tension control force data.

[0030] Preferably, the S5 step includes:

[0031] Based on the curvature compensation tension control force data, the jack is controlled for graded loading. When the oil pressure reaches the designed control value, the elongation of each measuring point of the steel strand is measured to generate an actual elongation data set.

[0032] Call the theoretical elongation calculation value in the design specification, calculate the deviation percentage between the actual elongation data set and the theoretical value for each measuring point, and generate an elongation deviation rate table;

[0033] According to the allowable deviation threshold of the specification, determine whether the data of each measuring point in the extension deviation rate table exceeds the limit, perform anchoring operations on qualified measuring points, record the anchoring shrinkage and stress value, and generate the final tensioning stress confirmation record.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] High-precision inclination sensors are used to monitor the support system's posture changes in real time. A three-dimensional deformation model is constructed based on the dynamic wind load spectrum. Pre-camber compensation coordinates are generated through vector superposition operations to improve formwork curvature control accuracy. Total station scanning is combined with BIM model theoretical value comparison to establish a matrix containing axial deviation and overrun codes, enabling quantitative identification of pipeline positioning deviations. Weak stiffness sections are delineated based on standard thresholds, optimizing casting unit division and construction sequence parameters to reduce the cumulative effect of structural deformation. Pipeline curvature and time-varying friction coefficients are collected in real time to construct a friction loss compensation model. This model, combined with graded tensioning parameters, ensures uniform prestress distribution in high-curvature sections. The elongation deviation rate and anchor retraction are dynamically monitored. Final tensioning records are generated through graded loading and threshold judgment, enabling closed-loop control of the tensioning process. Through dynamic modeling, real-time deviation analysis, time-varying parameter compensation, and graded control, this solution improves the forming accuracy and stress stability of high-altitude, high-curvature components, reducing rework rates and material loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0037] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0038] Example 1, as Figure 1 As shown, a method for constructing a high-altitude large-span curved prestressed beam comprises the following steps:

[0039] S1: Deformation prediction and formwork pre-adjustment of the high-altitude support system. An inclination sensor is placed on the top of the high-altitude support system pole to obtain initial posture data. A three-dimensional load model is constructed by combining the curvature radius of the curved formwork with the wind load spectrum. The dynamic deformation trajectory of the support system is calculated using the concrete rheological parameters. The deformation variable and the design curvature are vector-superimposed to generate the pre-camber compensation coordinates of the curved formwork.

[0040] S2: Prestressed pipe spatial positioning verification: After installing the template based on the pre-camber compensation coordinates of the arc template, use a total station to scan the 3D coordinates of the prestressed pipe, extract the theoretical coordinates of the BIM design model to construct a difference matrix, calculate the absolute values of the X / Y / Z axial deviations, and generate the prestressed pipe spatial deviation matrix;

[0041] S3: Segmented casting sequence planning: call the prestressed pipe spatial deviation matrix to identify the axial overrun section according to the GB allowable deviation, divide the stiffness weak area according to the deviation amount, generate the beam segment coding sequence with low first and high later, and establish the segmented casting sequence plan;

[0042] S4: Calculation of tension control force in large curvature sections: Acquire concrete strength signals based on the segmented pouring sequence plan, measure the curvature of the prestressed pipe to generate a distribution map, collect time-varying data on the friction coefficient of the steel strand to construct a friction loss curve, calculate additional tension force based on anchor retraction, and generate curvature compensation tension control force data;

[0043] S5: Review of the elongation during the tensioning process. Control the loading process of the tensioning jack according to the curvature compensation tensioning control force data. Measure the actual elongation of the steel strand when the oil pressure reaches the standard stage. Calculate the deviation rate by comparing it with the theoretical value. Complete the final tensioning after executing the threshold judgment and generate the final tensioning stress confirmation record.

[0044] The pre-camber compensation coordinates of the curved formwork include the X / Y / Z compensation coordinates of the support points, the pre-camber adjustment amount, and the wind load deformation correction coefficient. The spatial deviation matrix of the prestressed pipe specifically includes the X / Y / Z deviation values of each measuring point, the composite angle of the deviation vector, and the over-limit section code. The segmented pouring sequence plan includes the three-dimensional grid code of the pouring unit, the unit construction timing parameters, and the technical indicators of joint treatment. The curvature compensation tensioning control force data includes the graded tensioning force setting value, the friction compensation coefficient, and the load-holding and stabilization time. The final tensioning stress confirmation record specifically refers to the measured stress value, the theoretical deviation rate, and the acceptance status identification code.

[0045] Step S1 includes:

[0046] An inclination sensor is placed on the top of the vertical pole to obtain the inclination data and initial coordinates of each node of the support system. Combined with the curvature radius of the arc template and the wind load spectrum parameters, a three-dimensional load model is constructed to generate a support system posture data set.

[0047] Tilt sensors were placed on the top of the poles in a 3m×3m grid, with a measurement accuracy of 0.1° and a sampling frequency of 10Hz. The X / Y / Z axial tilt data of each node of the support system were collected, and the GPS positioning coordinates were recorded simultaneously. Combined with the curvature radius R=85m parameter of the arc template in the design drawing, the wind pressure value of 0.25kN / m corresponding to the wind speed of 20m / s measured at the weather station was obtained. 2 , the inclination angle data is converted into node displacement, and a three-dimensional load model including node coordinates, displacement, and wind pressure values is established. For example, the initial inclination angle of node A (X=15, Y=30, Z=45) is 0.3°. After coordinate conversion, the displacement ΔX=2.1mm, ΔY=1.8mm, and ΔZ=3.5mm are obtained. After vector superposition with the wind pressure value, a support system posture data set including the displacement vector is generated.

[0048] The elastic modulus and creep coefficient of concrete rheological parameters are used to calculate the deformation displacement under the coupling of wind load and concrete deadweight based on the support system posture data set, and generate dynamic deformation trajectory parameters.

[0049] The elastic modulus E = 35 GPa and creep coefficient φ = 2.3 from the C40 concrete mix report are used. Based on the node displacements in the attitude dataset, a wind load of 0.25 kN / m is calculated. 2 With concrete density 2400kg / m 3 Equivalent load combination, for example, beam segment B has a volume of 12m 3 The corresponding deadweight load G = 12 × 2400 × 9.8 = 282.24 kN is vector-synthesized with the wind load F = 0.25 × 36 = 9 kN. According to the node stiffness matrix K = EA / L (A = 0.25m 2 ,L=6m) calculate the deformation displacement δ=Σ(F×L) / (E×A)=(291.24×6) / (35e9×0.25)=0.002m, and generate the dynamic deformation trajectory parameters including the time-varying displacement curve.

[0050] The dynamic deformation trajectory parameters and the designed curvature coordinates are vector-superimposed, the deformation components are decomposed along the X / Y / Z axes, the template control point coordinates are adjusted according to the curvature correction formula, and the arc template pre-camber compensation coordinates are generated.

[0051] Extract the maximum displacement δ_max=5.2mm from the dynamic deformation trajectory parameters, and according to the design curvature coordinate equation Z=0.0015X 2 +0.0008Y 2Perform coordinate transformation and decompose the deformation into X / Y / Z axial components ΔX'=δ_max×cosα=5.2×cos30°=4.5mm, ΔY'=5.2×cos60°=2.6mm, ΔZ'=5.2×sin30°=2.6mm, substitute into the curvature correction formula ΔZ_corr=ΔZ'+0.15ΔX'+0.08ΔY'=2.6+0.15×4.5+0.08×2.6=3.4mm, adjust the coordinate value of the control point P (X=20, Y=40) Z_new=Z_design+ΔZ_corr=1250+3.4=1253.4mm, and generate the arc template pre-camber compensation coordinates including the corrected coordinates.

[0052] Step S2 includes:

[0053] After installing the template based on the pre-camber compensation coordinates of the arc template, use a total station to scan the X / Y / Z coordinates of each measuring point on the prestressed pipe, extract the theoretical coordinates of the corresponding measuring points in the BIM design model, and generate a table of measured-theoretical coordinates for the pipe.

[0054] After the installation of the pre-camber compensation coordinates of the arc template is completed, a total station is used to perform a three-dimensional scan of the prestressed pipe with a distance measurement accuracy of 0.5 mm. The measuring point spacing is set to 1.5 m, and the measured coordinates of the measuring point P1 (X = 10234.56, Y = 8765.43, Z = 25.78) are obtained. The corresponding theoretical coordinates of the measuring point P1' (X = 10234.50, Y = 8765.40, Z = 25.80) are simultaneously extracted from the BIM model. A comparison table containing the measuring point number, measured coordinates, and theoretical coordinates is established. For example, the measured Z = 26.15 mm and the theoretical Z = 26.00 mm of the measuring point P2 form a 0.15 mm deviation record. A pipeline measured-theoretical coordinate alignment table containing 200 measuring point coordinate pairs is generated.

[0055] Call the pipeline measured-theoretical coordinate alignment table, calculate the difference between the X / Y / Z axial measured value and the theoretical value at each measuring point, take the absolute value operation, and generate the axial deviation absolute value table;

[0056] Call the measured X = 15432.10mm and theoretical X = 15432.00mm data of measuring point P3 in the alignment table, calculate the axial deviation ΔX = 15432.10-15432.00 = 0.10mm, take the absolute value |ΔX| = 0.10mm, and similarly calculate the Y-axis |ΔY| = 0.05mm and the Z-axis |ΔZ| = 0.12mm. Calculate row by row according to the order of measuring points. For example, the X / Y / Z deviations of measuring point P4 are 0.08mm, 0.15mm, and 0.20mm, respectively. Generate a three-column data table containing the absolute values of the axial deviations and store it in CSV format.

[0057] The deviation values of each measuring point in the axial deviation absolute value table are classified and summarized according to the X / Y / Z axis, and a three-dimensional matrix structure is constructed. The data are arranged and stored according to the measuring point number to generate the prestressed pipe spatial deviation matrix.

[0058] The data of X = 0.12 mm, Y = 0.18 mm, and Z = 0.25 mm of measuring point P5 in the axial deviation absolute value table are respectively assigned to the i = 5 rows and j = 1 / 2 / 3 columns of the three-dimensional matrix according to the X / Y / Z axes. The matrix dimension is set to n × 3 (n = 200), and the data are arranged in sequence according to the measuring point numbers 1-200. They are stored as a three-dimensional array with the structure of [[0.10, 0.05, 0.12], [0.08, 0.15, 0.20], ...] to generate the prestressed pipe spatial deviation matrix that can be used for subsequent analysis.

[0059] The S3 steps include:

[0060] Call the prestressed pipe spatial deviation matrix, compare the absolute value of the deviation with the threshold value according to the X / Y / Z axial allowable deviation threshold in the GB specification, mark the exceeding measurement point number, and generate the exceeding section code table;

[0061] The data of measuring point P7 (X = 6.2 mm, Y = 4.8 mm, Z = 5.1 mm) in the prestressed pipe spatial deviation matrix is called. The data is compared with the ±5 mm tolerance threshold for the X / Y / Z axial directions in the GB / T50204-2015 specification. A logical judgment is performed on each measuring point: if |X| > 5, |Y| > 5, or |Z| > 5, the data is marked as out of limit. For example, measuring point P12 (X = 5.3 mm) exceeds the threshold and is recorded in the code table as "P12_X out of limit." A count of 35 out-of-limit points is collected from the 200 measuring points in the matrix. A code table is generated that includes the out-of-limit axial type and measuring point coordinates. The code table is stored in the format of [P12, X, 5.3, 15230, 48760, 25.6] for the out-of-limit section.

[0062] Based on the over-limit section code table, the distance between adjacent over-limit measuring points and the average deviation are calculated, the areas are arranged in descending order by deviation, the stiffness weakness levels are divided, and a stiffness weakness area distribution map is generated;

[0063] Based on the distance calculation between adjacent measuring points P15 (X=15235, Y=48750) and P16 (X=15237, Y=48752) in the over-limit section code table: ΔX=2m, ΔY=2m, straight-line distance √(2 2 +2 2)=2.83m, take the average X deviation of the two measuring points (5.8+6.2) / 2=6.0mm, and divide the area into three levels according to the deviation: Level I (≥6mm), Level II (4-6mm), and Level III (<4mm). For example, area A includes measuring points P15-P20, and is classified as Level I with an average deviation of 6.5mm. Generate a color-coded distribution map of weak stiffness areas, with red representing Level I, yellow representing Level II, and green representing Level III.

[0064] According to the distribution map of weak stiffness areas, the construction sequence is arranged according to the principle of priority for low stiffness areas. The beam body is divided into continuous casting sections and assigned unique codes to generate a segmented casting sequence plan.

[0065] According to the position of the level I area in the stiffness weak area distribution map, the beam body is divided into three sections for casting: the first section covers the measuring points P15-P20 (coordinates X=15230-15250), coded S1, the second section covers the measuring points P25-P30 (X=15260-15280) coded S2, and the last section covers the measuring points P35-P40 (X=15290-15310) coded S3. The segmentation scheme is generated in the order of S1→S2→S3 and stored as a segmented casting sequence scheme with the structure of [segment number, starting point X, ending point X, casting sequence].

[0066] The S4 step includes:

[0067] Obtain the concrete strength monitoring value of each pouring section according to the segmented pouring sequence plan, measure the curvature radius of each measuring point of the prestressed pipe, and generate the pipe curvature distribution map according to the distance between the measuring points;

[0068] According to the construction plan of S1 section (X=15230-15250) in the segmented pouring sequence plan, a rebound hammer was used to test the concrete strength on the third day after pouring, and the strength value of measuring point P5 was obtained as 35.2 MPa. Simultaneously, a total station was used to measure the curvature radius of the measuring points of the prestressed pipe in this section. For example, the coordinates of the three points of measuring point P6 were (X=15235, Y=48760, Z=25.8), (X=15237, Y=48762, Z=25.9), and (X=15239, Y=48764, Z=26.1). The curvature radius R=√[(15237-15235)] was calculated using the three-point circle formula. 2 +(48762-48760) 2 ] / [2×0.1]=85.2m, and generate a distribution map of curvature values of 50 measuring points at a measuring point spacing of 2m, which is stored in the format of [measuring point number, curvature radius].

[0069] The measured values of the friction coefficient of the steel strand at different tensioning stages are collected, the changes in the friction coefficient are recorded in time series, and the relationship curve between the friction coefficient and the tensioning time is fitted to generate a time-varying friction loss curve;

[0070] During the tensioning stage, a pressure sensor was used to record the friction coefficient of the steel strand. When the initial tensioning force was 100 kN, the friction coefficient μ1 was 0.18, and when the tension was increased to 150 kN, μ2 was 0.22. The data sequence [0.18, 0.20, 0.22, 0.23] was obtained by continuous monitoring for 120 minutes. The least squares method was used to fit μ = 0.18 + 0.0004t (t is minutes), and a time-varying friction loss curve was generated and stored as a time-friction coefficient correspondence table. The time step was 5 minutes and the friction coefficient accuracy was 0.001.

[0071] The pipeline curvature distribution map and time-varying friction loss curve are called up, combined with the design value of anchor retraction, to calculate the additional tension compensation value of each measuring point, distribute the tension control force according to the curvature weight, and generate curvature compensated tension control force data.

[0072] The curvature weight coefficient k = 1 / R = 0.0125 corresponding to the curvature radius R = 80m of measuring point P7 is called. Combined with μ = 0.20 at t = 60 minutes in the time-varying friction loss curve and the anchor retraction Δ = 5mm, the additional tension compensation value ΔF = μ × k × Δ × E × A = 0.20 × 0.0125 × 5 × 195000 × 140 = 34,125N is calculated and distributed to each measuring point according to the curvature weight, generating the curvature compensation tension control force data including the measuring point number and compensation tension force.

[0073] Step S5 includes:

[0074] Based on the curvature compensation tension control force data, the jack is controlled for graded loading. When the oil pressure reaches the designed control value, the elongation of each measuring point of the steel strand is measured to generate an actual elongation data set.

[0075] Based on the compensation value ΔF = 32.5 kN of the measuring point P8 in the curvature compensation tension control force data, the control jack is loaded in stages of 20% → 50% → 80% → 100%. When the design control force of 150 kN is reached, a laser rangefinder is used to measure the change in the distance between the marking points at both ends of the measuring point P8 of the steel strand. The initial length L0 = 10.000 m, and after loading L1 = 10.125 m, the actual elongation ΔL = 125 mm is calculated, and an actual elongation data set containing the elongation data of 50 measuring points is generated. The storage format is [measuring point number, control force value, elongation].

[0076] Call the theoretical elongation calculation value in the design specification, calculate the deviation percentage between the actual elongation data set and the theoretical value for each measuring point, and generate an elongation deviation rate table;

[0077] The theoretical elongation calculation formula in JTJ041-2000 is ΔLtheoretical = (F×L) / (E×A), where F = 150kN, L = 10m, E = 195GPa, and A = 140mm. 2, it is calculated that ΔL theory = (150000×10) / (195e3×140) = 0.110m = 110mm, the actual ΔL of measuring point P8 = 125mm, the deviation rate = (125-110) / 110×100% = 13.6%, and an elongation deviation rate table containing the measuring point number and deviation rate value is generated. The data accuracy is retained to 0.1%.

[0078] According to the allowable deviation threshold of the specification, determine whether the data of each measuring point in the extension deviation rate table exceeds the limit, perform anchoring operations on qualified measuring points, record the anchoring shrinkage and stress value, and generate the final tensioning stress confirmation record.

[0079] According to the ±5% allowable deviation threshold specified in the specification, the deviation rate of measuring point P8 (13.6%) was judged to be out of limit, and the deviation rate of measuring point P9 (4.2%) was qualified. Anchoring operation was performed on the qualified measuring points, and the retraction amount Δ=3mm after anchoring was recorded. The stress sensor displayed a maintained stress value of 148.5kN, and a final tensioning stress confirmation record containing data such as [measuring point P9, stress 148.5kN, retraction 3mm] was generated.

[0080] Example 2: Based on the above example 1, this method is applied to the construction of large curvature prestressed box girders of urban viaducts.

[0081] A certain urban viaduct project required the construction of a curved prestressed concrete box girder with an 80m radius, a 2.5m height, a 40m span, and a designed tension control stress of 1395MPa. Construction faced technical difficulties such as the high-altitude support system's sensitive deformation, prestress loss due to pipeline positioning deviations, and significant friction effects in sections with large curvatures.

[0082] Method implementation process:

[0083] Dynamic adjustment of support system

[0084] 0.001° precision inclination sensors are installed at key nodes of the support frame (e.g. the initial inclination angle of measuring point J05 is 0.25°), attitude data is collected every 10 minutes, and real-time wind load spectrum is input synchronously (e.g. wind speed 8m / s corresponds to wind pressure 0.4kN / m 2 ), calculate the dynamic offset of the support system through the three-dimensional deformation model (such as the cumulative deformation in the X direction +3.2mm), superimpose the pre-arch of the design curvature radius of 80m (pre-arch value Δ=12mm), and generate the template compensation coordinates (such as the adjusted coordinates of the measuring point T12 X=15235.6, Y=48762.3, Z=25.8).

[0085] Quantification of pipeline positioning deviation

[0086] A 0.5mm-level total station was used to scan the pipeline measuring points (such as the measured X=15240.2 / Y=48758.7 / Z=25.6 of P07), and compared with the theoretical coordinates of the BIM model (X=15240.0 / Y=48759.0 / Z=25.5). The axial deviation (ΔX=+0.2mm, ΔY=-0.3mm, ΔZ=+0.1mm) was calculated, and a 200×3 deviation matrix was constructed. The out-of-limit measuring points were marked (such as ΔY=5.3mm of P19 exceeded the limit by ±5mm).

[0087] Segmental pouring optimization

[0088] Divide the over-limit sections according to GB / T 50204 (e.g., area A contains 6 consecutive over-limit points), use every 8 meters as a pouring unit (unit 1: X=15230-15238), set the pouring interval time ≥72 hours, generate a construction sequence parameter table (unit 1→unit 3→unit 2), and reduce cumulative deformation (misalignment at unit joints ≤1mm).

[0089] Curvature friction compensation

[0090] Measure the pipeline curvature radius (e.g., R = 78 m corresponds to curvature k = 0.0128), collect time-varying data of the friction coefficient during the tensioning process (initial μ = 0.18 → μ = 0.23 after 120 minutes), calculate the additional tensioning force ΔF = μ × k × E × A × ΔL = 0.2 × 0.0128 × 1.95e5 × 140 × 0.005 = 34.9 kN, and generate a compensation control force table (e.g., the control force at measuring point P22 is adjusted from 1395 MPa to 1430 MPa).

[0091] Gradual tension closed-loop control

[0092] Load in stages of 20% → 50% → 100%, monitor the elongation (e.g., the measured ΔL in stage three is 128mm vs. the theoretical value of 120mm), suspend adjustment when the deviation rate exceeds 6.7%, record the retraction amount after anchoring after passing the test (e.g., 3.2mm < 5mm threshold), and generate a final tensioning record sheet (stress retention rate ≥ 95%, retraction compliance rate 100%).

[0093] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a high-altitude, large-span, curved prestressed beam, comprising the following steps: S1: Deformation prediction of high-altitude support system and template pre-adjustment: High-precision inclination sensors are deployed at key nodes of the high-altitude support system to obtain posture data. A three-dimensional deformation model is constructed by combining the curvature radius of the arc template with the dynamic wind load spectrum. The dynamic deformation of the support system is calculated and superimposed with the design curvature to generate the pre-camber compensation coordinates of the arc template. S2: Prestressed pipe spatial positioning verification: Based on the pre-camber compensation coordinates of the arc template, the three-dimensional coordinates of the prestressed pipe are scanned by a total station and compared with the theoretical values of the BIM design model. The axial deviation is calculated to generate the prestressed pipe spatial deviation matrix; S3: Segmented pouring sequence planning: calling the prestressed pipe spatial deviation matrix to identify the over-limit section according to the GB allowable deviation, dividing the pouring units to generate a segmented pouring sequence plan; S4: Calculation of tension control force in large curvature sections. Based on the segmented pouring sequence plan, real-time collection of pipe curvature and time-varying friction coefficient is performed to calculate additional tension force and generate curvature-compensated tension control force data. S5: Review the elongation during the tensioning process. Measure the elongation based on the curvature compensation tensioning control force data and perform standard threshold judgment to complete the graded final tensioning and generate the final tensioning stress confirmation record.

2. The method for constructing a high-altitude, large-span, curved prestressed beam according to claim 1, wherein: The pre-camber compensation coordinates of the arc formwork include the X / Y / Z compensation coordinates of the support point, the pre-camber adjustment amount, and the wind load deformation correction coefficient. The prestressed pipe spatial deviation matrix specifically includes the X / Y / Z deviation values of each measuring point, the deviation vector synthesis angle, and the over-limit section code. The segmented casting sequence plan includes the casting unit three-dimensional grid code, unit construction timing parameters, and joint processing technical indicators. The curvature compensation tensioning control force data includes the graded tensioning force setting value, friction compensation coefficient, and load-holding and stabilization time. The final tensioning stress confirmation record specifically refers to the measured stress value, theoretical deviation rate, and acceptance status identification code.

3. The method for constructing a high-altitude, large-span, curved prestressed beam according to claim 1, wherein: The S1 step includes: An inclination sensor is placed on the top of the vertical pole to obtain the inclination data and initial coordinates of each node of the support system. Combined with the curvature radius of the arc template and the wind load spectrum parameters, a three-dimensional load model is constructed to generate a support system posture data set. The elastic modulus and creep coefficient of concrete rheological parameters are used to calculate the deformation displacement under the coupling of wind load and concrete deadweight based on the support system posture data set, and generate dynamic deformation trajectory parameters. The dynamic deformation trajectory parameters and the designed curvature coordinates are vector-superimposed, the deformation components are decomposed along the X / Y / Z axes, the template control point coordinates are adjusted according to the curvature correction formula, and the arc template pre-camber compensation coordinates are generated.

4. The method for constructing a high-altitude, large-span, curved prestressed beam according to claim 1, characterized in that: The S2 step includes: After installing the template based on the pre-camber compensation coordinates of the arc template, use a total station to scan the X / Y / Z coordinates of each measuring point on the prestressed pipe, extract the theoretical coordinates of the corresponding measuring points in the BIM design model, and generate a table of measured-theoretical coordinates for the pipe. Call the pipeline measured-theoretical coordinate alignment table, calculate the difference between the X / Y / Z axial measured value and the theoretical value at each measuring point, take the absolute value operation, and generate the axial deviation absolute value table; The deviation values of each measuring point in the axial deviation absolute value table are classified and summarized according to the X / Y / Z axis, and a three-dimensional matrix structure is constructed. The data are arranged and stored according to the measuring point number to generate the prestressed pipe spatial deviation matrix.

5. The method for constructing a high-altitude, large-span curved prestressed beam according to claim 1, characterized in that: The S3 step includes: Call the prestressed pipe spatial deviation matrix, compare the absolute value of the deviation with the threshold value according to the X / Y / Z axial allowable deviation threshold in the GB specification, mark the exceeding measurement point number, and generate the exceeding section code table; Based on the over-limit section code table, the distance between adjacent over-limit measuring points and the average deviation are calculated, the areas are arranged in descending order by deviation, the stiffness weakness levels are divided, and a stiffness weakness area distribution map is generated; According to the distribution map of weak stiffness areas, the construction sequence is arranged according to the principle of priority for low stiffness areas. The beam body is divided into continuous casting sections and assigned unique codes to generate a segmented casting sequence plan.

6. The method for constructing a high-altitude, large-span, curved prestressed beam according to claim 1, characterized in that: The S4 step includes: Obtain the concrete strength monitoring value of each pouring section according to the segmented pouring sequence plan, measure the curvature radius of each measuring point of the prestressed pipe, and generate the pipe curvature distribution map according to the distance between the measuring points; The measured values of the friction coefficient of the steel strand at different tensioning stages are collected, the changes in the friction coefficient are recorded in time series, and the relationship curve between the friction coefficient and the tensioning time is fitted to generate a time-varying friction loss curve; The pipeline curvature distribution map and time-varying friction loss curve are called up, combined with the design value of anchor retraction, to calculate the additional tension compensation value of each measuring point, distribute the tension control force according to the curvature weight, and generate curvature compensated tension control force data.

7. The method for constructing a high-altitude, large-span, curved prestressed beam according to claim 1, characterized in that: The S5 step includes: Based on the curvature compensation tension control force data, the jack is controlled for graded loading. When the oil pressure reaches the designed control value, the elongation of each measuring point of the steel strand is measured to generate an actual elongation data set. Call the theoretical elongation calculation value in the design specification, calculate the deviation percentage between the actual elongation data set and the theoretical value for each measuring point, and generate an elongation deviation rate table; According to the allowable deviation threshold of the specification, determine whether the data of each measuring point in the extension deviation rate table exceeds the limit, perform anchoring operations on qualified measuring points, record the anchoring shrinkage and stress value, and generate the final tensioning stress confirmation record.

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