Construction control method for cable-stayed bridge

Abstract

The application discloses a cable-stayed bridge construction control method and relates to the technical field of bridge construction control, which comprises the following steps: collecting the measured values of the elevations of each measuring point of a main beam, the measured values of the cable forces of each cable and the measured values of the environmental temperatures at each construction stage of each tensioned cable; obtaining the theoretical elevation value and the theoretical cable force value of the current stage, correcting the theoretical value according to the difference between the measured temperature and the reference temperature by using the material linear expansion coefficient to obtain the corrected theoretical value; calculating the elevation deviation value and the cable force deviation value; if the absolute value of any elevation deviation is greater than a first threshold value or the absolute value of any cable force deviation is greater than a second threshold value, then solving the cable force adjustment amount of each cable based on the influence matrix method, and entering the next construction stage after tensioning or releasing according to the adjustment amount; otherwise, directly entering the next construction stage. The application can effectively eliminate the temperature interference, realize the systematic solution of the cable force adjustment amount, form a closed-loop control, and take into account the control precision and the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of bridge construction control technology. More specifically, this invention relates to a method for controlling the construction of cable-stayed bridges. Background Technology

[0002] As a highly statically indeterminate structure, cable-stayed bridges exhibit a typical "construction and shaping simultaneously" characteristic during construction. In the phased construction process of tensioning the stay cables one by one, the main girder alignment and cable forces are interdependent and mutually influential. Deviations at any construction stage will have a cumulative effect on subsequent stages and even the final bridge condition. Therefore, construction control is a core technical aspect of cable-stayed bridge construction. Its goal is to control the main girder elevation and cable forces within the design limits at each construction stage, ultimately achieving the ideal bridge alignment and internal force distribution.

[0003] Currently, the construction control of cable-stayed bridges typically adopts a basic model of "calculation-measurement feedback-parameter adjustment." In this traditional method, the design unit provides theoretical elevation and cable force values ​​for each construction stage. On-site, measured data is obtained using total stations and cable force testing equipment. When the deviation between the measured and theoretical values ​​exceeds an empirical threshold, control personnel judge based on experience whether cable force adjustment is necessary and manually calculate the adjustment amount. This control method, relying on manual experience, has significant shortcomings: First, existing methods typically only employ simple linear corrections; second, the criteria for judging whether a deviation exceeds the limit are often fixed and cannot be dynamically adjusted as construction progresses or structural stiffness changes, easily leading to unnecessary over-adjustment or untimely adjustments; third, when the deviation exceeds the allowable range, determining the cable force adjustment amount largely depends on the operator's experience or repeated trial calculations, lacking a systematic and efficient solution method, resulting in poor convergence of the adjustment process and affecting construction progress and control accuracy.

[0004] Therefore, it is necessary to design a technical solution that can overcome the above-mentioned defects. Summary of the Invention

[0005] One objective of this invention is to provide a construction control method for cable-stayed bridges, which can effectively eliminate temperature interference, realize the systematic solution of cable force adjustment, form closed-loop control, and balance control accuracy and construction efficiency.

[0006] To achieve these objectives and other advantages of the present invention, according to one aspect of the present invention, a construction control method for a cable-stayed bridge is provided, comprising: S1: at each construction stage of the tensioned cable of the cable-stayed bridge, collecting measured values ​​of the elevation of each measuring point of the main beam, the measured values ​​of the cable force of each cable, and the measured values ​​of the ambient temperature at the current stage; S2: based on design drawings and construction simulation calculations, obtaining theoretical values ​​of the elevation of each measuring point of the main beam and the theoretical values ​​of the cable force of each cable at the current construction stage, and using the linear expansion coefficient of the structural materials, correcting the theoretical values ​​of the elevation of each measuring point of the main beam and the theoretical values ​​of the cable force of each cable according to the difference between the measured values ​​of the ambient temperature and the preset reference temperature value, to obtain the corrected theoretical values ​​of the elevation of each measuring point of the main beam and the corrected theoretical values ​​of the cable force of each cable. S3: Calculate the elevation deviation of each measuring point on the main beam. The elevation deviation is equal to the measured elevation of each measuring point on the main beam minus the corrected theoretical elevation of each measuring point on the main beam. Calculate the cable force deviation of each stay cable. The cable force deviation is equal to the measured cable force of each stay cable minus the corrected theoretical cable force of each stay cable. S4: When the absolute value of the elevation deviation of any measuring point on the main beam is greater than the first threshold or the absolute value of the cable force deviation of any stay cable is greater than the second threshold, solve the cable force adjustment amount of each stay cable based on the influence matrix method, and execute S5; otherwise, directly proceed to the next construction stage. S5: Perform tensioning or detensioning operations on the corresponding stay cables according to the cable force adjustment amount, and then proceed to the next construction stage.

[0007] Furthermore, in S1, measurements are taken using magnetic flux sensors or vibrating wire pressure rings installed at the anchorage ends of the stay cables, with a sampling frequency of not less than 1Hz. The average value of the measured data is taken as the measured cable force of the stay cable. The measured global ambient temperature is obtained by synchronously collecting temperature sensors in at least three Stevenson screens at the bridge tower, mid-span of the main beam, and both ends, and taking the arithmetic mean. The measured local ambient temperature at each measuring point is obtained synchronously at the same measuring point location when collecting the measured elevation values ​​of each measuring point on the main beam. In S2, the measured ambient temperature used to correct the theoretical elevation values ​​of each measuring point on the main beam is the measured local ambient temperature value of the corresponding measuring point. The measured ambient temperature used to correct the theoretical cable force values ​​of each stay cable is the measured global ambient temperature value.

[0008] Furthermore, an initial calculation model is established, which includes the bending stiffness of the main beam, the elastic modulus of the stay cables, and the self-weight intensity of the main beam as parameters to be corrected. Measured data from at least two previous construction stages with tensioned stay cables are obtained, including measured elevations of various measuring points on the main beam and measured cable forces in those stages. Using the theoretical elevations of the main beam at each measuring point and the theoretical cable forces in each stay cable corresponding to the construction stages with tensioned stay cables as objectives, least squares optimization or Kalman filtering algorithms are employed to inversely correct the parameters to be corrected, minimizing the sum of squared errors in elevation calculation and cable force calculation in the corrected calculation model during the construction stages with tensioned stay cables. Finally, using the corrected calculation model, the theoretical elevations of various measuring points on the main beam and the theoretical cable forces in each stay cable are calculated for the current construction stage.

[0009] Furthermore, the linear expansion coefficient of the main beam material is used, and corrections are made based on the difference between the measured local ambient temperature at the measuring point and the preset reference temperature. The corrected theoretical elevation value = original theoretical elevation value × [1 + α] 梁 ×(T 局部 -T 基准 )], where α 梁 The coefficient of linear expansion of the main beam material, T 局部 T represents the measured local ambient temperature at this measuring point. 基准 The preset reference temperature value is used; the linear expansion coefficient of the cable-stayed bridge material is adopted, and the value is corrected based on the difference between the measured global ambient temperature and the preset reference temperature value. The corrected theoretical cable force value = original theoretical cable force value + β × α 索 ×(T 全局 -T 基准 )×E 索 ×A 索 , where α 索 T is the coefficient of linear expansion of the cable-stayed bridge material. 全局 The measured global ambient temperature is given, β is the cable temperature sensitivity coefficient, ranging from 0.8 to 1.2, and E... 索 Let A be the elastic modulus of the stay cable. 索 This represents the cross-sectional area of ​​the stay cable.

[0010] Further, the first threshold and the second threshold are set as follows: The absolute values ​​of the elevation deviations of all measuring points on the main beam are obtained in at least three construction stages before the current construction stage where the stay cables have been tensioned. A first average value and a first standard deviation are calculated. The first threshold = first average value + 2 × first standard deviation, and is not less than 3 mm and not more than 30 mm. The absolute values ​​of the cable force deviations of all stay cables are obtained in at least three construction stages before the current construction stage where the stay cables have been tensioned. A second average value and a second standard deviation are calculated. The second threshold = second average value + 2 × second standard deviation, and is not less than 2% of the design cable force of the stay cable and not more than 15% of the design cable force of the stay cable.

[0011] Furthermore, an initial influence matrix M0 is established, and the elements m in the initial influence matrix M0 are... ij This represents the influence coefficient of the unit cable force change of the j-th stay cable on the elevation of the i-th main beam measuring point; it also represents the actual cable force adjustment vector ΔF of all tensioned stay cables completed before the current construction stage. actual With the corresponding actual change vector of elevation ΔH actual The initial influence matrix M0 is corrected online using a recursive least squares algorithm to obtain the current influence matrix M; the cable force adjustment ΔF of each stay cable is then used. j For unknown variables, the following quadratic programming model with inequality constraints is established; The objective function is: The constraints are: ; Among them, H i target H is the corrected theoretical elevation value of the i-th main beam measuring point. i current w is the measured elevation value of the i-th main beam measuring point. i λ is the weighting coefficient for the i-th main beam measuring point, λ is the penalty coefficient for cable force adjustment, and F j design Let F be the design cable force value of the j-th stay cable. j measured Let be the measured cable force of the j-th stay cable, n be the total number of measuring points on the main girder, and m be the total number of stay cables; solve the quadratic programming model to obtain the cable force adjustment ΔF for each stay cable. j .

[0012] Furthermore, in the initial calculation model of the current construction phase, a unit cable force is applied to each stay cable while keeping the cable forces of other stay cables constant. The elevation change of each main beam measuring point is extracted, and the elevation change of the i-th main beam measuring point caused by the unit cable force of the j-th stay cable is used as element m in the initial influence matrix. ij .

[0013] Furthermore, in S5, the stay cables requiring adjustment are sorted from largest to smallest absolute value of their tension adjustment, prioritizing the stay cables with the largest absolute values. For each stay cable requiring adjustment, its tension adjustment is divided into three levels: Level 1 is 20% of the target adjustment, Level 2 is 30%, and Level 3 is 50%. After each level of tensioning or releasing is completed, the process is paused and the measured elevation values ​​of each measuring point on the main beam and the measured tension values ​​of each stay cable are re-acquired. S2 to S4 are then executed again to update the remaining tension adjustments. When adjustments are needed for stay cables on both sides of the same bridge tower or at the same symmetrical position, a synchronous symmetrical tensioning or releasing method is adopted, with the synchronous time difference between the adjustments on both sides not exceeding two seconds. During the adjustment process, the cable force changes of the two stay cables adjacent to the currently adjusted stay cable are monitored in real time. If the cable force change of the adjacent stay cable exceeds one percent of its design cable force value, the current adjustment is paused, and the cable force change of the adjacent stay cable is used as an additional input to re-execute the influence matrix method in S4 to solve the problem, update the cable force adjustment amount of the current stay cable and its adjacent stay cables, and then continue the adjustment.

[0014] Furthermore, before proceeding to the next construction phase, the process includes: re-collecting the measured elevation values ​​of each measuring point on the main beam and the measured cable force values ​​of each stay cable in the current construction phase, and repeating steps S2 to S4; if the absolute values ​​of the recalculated elevation deviations of all measuring points on the main beam are not greater than the first threshold, and the absolute values ​​of the cable force deviations of all stay cables are not greater than the second threshold, then proceeding to the next construction phase; otherwise, repeating steps S4-S5, performing tensioning or releasing operations according to the updated cable force adjustment amount, until the above conditions are met or the preset maximum number of iterations is reached; if the maximum number of iterations is reached but the conditions are still not met, a warning is issued and construction is stopped.

[0015] The present invention has at least the following beneficial effects: This invention simultaneously collects measured values ​​of main beam elevation, cable tension, and ambient temperature at each construction stage. Utilizing the linear expansion coefficient of structural materials, it corrects the theoretical elevation and cable tension values ​​based on the difference between the measured and reference temperatures. This effectively eliminates the interference of temperature changes on the construction control benchmark, making the calculation of deviations between measured and theoretical values ​​more accurate and reliable. When the absolute value of the elevation deviation at any main beam measuring point exceeds a first threshold, or the absolute value of the cable tension deviation at any cable exceeds a second threshold, the influence matrix method is used to systematically solve for the cable tension adjustment amount for each cable. This avoids the shortcomings of traditional methods that rely on manual experience or trial-and-error to determine the adjustment amount, improving the certainty and computational efficiency of the adjustment scheme. After tensioning or detensioning the corresponding cables according to the calculated cable tension adjustment amount, the next construction stage begins, forming a closed-loop control process of "measurement—correction—judgment—adjustment—progress." This proactively controls the structural state at each construction stage within allowable limits, effectively suppressing error accumulation and ensuring that the main beam alignment and cable tension distribution after bridge completion meet design requirements.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0017] Figure 1 This is a flowchart of one embodiment of this application. Detailed Implementation

[0018] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0019] It should be understood that terms such as "having," "comprising," and "including" used in the embodiments of this application do not exclude the presence or addition of one or more other elements or combinations thereof. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of components in a specific posture. If the specific posture changes, the directional indication will also change accordingly. When an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or may have an intervening element present. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element through an intervening element. Descriptions involving "first," "second," etc., in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0020] It should be noted that the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0021] In one embodiment, the construction control method for a cable-stayed bridge is implemented according to the following steps. The construction of a cable-stayed bridge is carried out in stages, with each stage completed after the tensioning of one or a pair of stay cables. In each stage of construction with tensioned stay cables, the main implementing body is the construction control computer system, which needs to collect three types of data for the current stage. The first type is the measured elevation values ​​of each measuring point on the main beam. Measuring points on the main beam can be set at certain intervals along the longitudinal direction, for example, optionally every 5 or 10 meters. The measuring point locations are usually pre-embedded leveling observation marks on the top or bottom surface of the main beam. Measurements are taken using a precision level or total station, with the measuring rod placed on the measuring point mark to read the elevation value. The second type is the measured cable tension values ​​of each stay cable. Magnetic flux sensors or vibrating wire pressure rings can be installed at the anchorage end of each stay cable. The sensor output signal is converted into cable tension values ​​through frequency analysis. The sampling frequency can be set to no less than 1 Hz, for example, 1 Hz or 2 Hz can be selected, and samples can be continuously collected for 10 seconds or 20 seconds. The arithmetic mean of all sampled values ​​is taken as the measured value of the cable force of the cable. This can eliminate instantaneous fluctuations caused by wind vibration, temporary vehicle loads, etc. The third type is the measured value of ambient temperature. No less than 3 louvered boxes can be set at the bridge tower, the mid-span of the main beam, and both ends of the main beam. For example, 4 or 5 can be selected. A platinum resistance temperature sensor is installed in each louvered box. All sensors collect data synchronously. The sampling time is the same as the elevation measurement time. Then, the arithmetic mean of these temperature values ​​is taken as the global measured value of ambient temperature. At the same time as the elevation is collected at each main beam measuring point, a patch temperature sensor or infrared thermometer is used at the same location to collect the measured value of the local ambient temperature at that point for subsequent correction. After data acquisition, based on the design drawings and the analysis results from construction simulation software (e.g., optionally ANSYS), the theoretical elevation values ​​of each measuring point on the main beam and the theoretical values ​​of each stay cable force are obtained for the current construction stage. These theoretical values ​​are calculated at the design reference temperature (e.g., optionally preset to 20 degrees Celsius or 25 degrees Celsius). Since the actual temperature differs from the reference temperature, the structure will experience thermal expansion and contraction deformation and redistribution of statically indeterminate internal forces, thus requiring correction to the theoretical values. Specifically, using the linear expansion coefficient of the structural materials, the linear expansion coefficient of the main beam concrete can be taken as 1.0 × 10⁻⁶. -5 At / ℃, the coefficient of linear expansion of the stay cable steel can be taken as 1.2×10. -5 / ℃. Based on the difference between the measured ambient temperature and the preset benchmark temperature, the theoretical elevation values ​​of each measuring point on the main beam and the theoretical cable force values ​​of each stay cable are corrected. Then, the elevation deviation value of each measuring point on the main beam is calculated, that is, the measured elevation value minus the corrected theoretical elevation value. The cable force deviation value of each stay cable is calculated, that is, the measured cable force value minus the corrected theoretical cable force value. Next, a judgment is made: if the absolute value of the elevation deviation value of any main beam measuring point is greater than the first threshold, or the absolute value of the cable force deviation value of any stay cable is greater than the second threshold, the adjustment process is triggered, and the cable force adjustment amount of each stay cable is solved based on the influence matrix method. The influence matrix method is constructed as follows: First, an influence coefficient matrix of the unit cable force change of each stay cable on the elevation of each measuring point on the main beam is established. Each column of this matrix corresponds to a stay cable, each row corresponds to a measuring point, and the matrix elements represent the elevation change caused by the unit cable force. Then, using the cable tension adjustment as the unknown vector, a system of linear equations or an optimization model is established to minimize the elevation deviation of each measuring point, and the adjustment is obtained by solving for it. The solution method can be the least squares method or constrained quadratic programming. After obtaining the adjustment, the next step is executed; otherwise, if all deviations are within the threshold, the next construction stage is directly entered. Finally, according to the solved cable tension adjustment, tensioning operations (increasing cable tension when the adjustment is positive) or detensioning operations (decreasing cable tension when the adjustment is negative) are performed on the corresponding stay cables. After the adjustment is completed, the next construction stage is entered. The trigger condition for the entire process is the completion of data acquisition and deviation calculation in the current stage, the output of which is the cable tension adjustment command, and the execution entities are the tensioning equipment (such as jacks) and the control system.

[0022] In existing technologies, construction control of cable-stayed bridges often neglects temperature correction. Furthermore, when elevation or cable tension deviations exceed empirical values, on-site engineers rely on their personal experience to determine whether and how much to adjust, leading to potentially significant differences in judgment among engineers. This embodiment differentiates between local and global temperatures and applies corrections accordingly, ensuring greater consistency between theoretical and measured values. Simultaneously, when deviations exceed limits, the system calculates cable tension adjustments using an influence matrix method instead of relying on manual experience, reducing arbitrariness. Through a closed-loop control process of "collection-correction-judgment-adjustment-progress," the system proactively keeps the state at each stage within acceptable limits, suppressing the propagation of errors to subsequent stages.

[0023] In one embodiment, the method for obtaining the measured cable force is further defined. A magnetic flux sensor or a vibrating wire pressure ring can be installed at the anchorage end of each stay cable. Both sensors utilize the relationship between the frequency and tension of the elastic element to measure the cable force. The sampling frequency can be set to no less than 1 Hz, for example, optionally 1 Hz, 2 Hz, or 5 Hz. The sampling duration is at least 10 seconds. All collected data points are arithmetically averaged, and the average value is taken as the measured cable force of that stay cable. This effectively filters out short-term random disturbances caused by wind excitation, vehicle traffic, etc. For obtaining the measured global ambient temperature, no fewer than three louvered boxes are installed at the top or middle of the bridge tower, at the mid-span of the main girder, and at the bridge deck positions furthest from the bridge towers at both ends of the main girder. For example, four louvered boxes can be optionally installed: one for each of the two tower columns, one at the mid-span of the main girder, and one at one end of the main girder. Each Stevenson screen houses a platinum resistance temperature sensor with an accuracy of 0.1 degrees Celsius. All sensors are synchronously sampled via a data acquisition device, with the sampling frequency matching the cable force sampling frequency. The readings from each sensor at the same moment are taken, and their arithmetic mean is calculated as the measured ambient temperature for this construction phase. For the measured local ambient temperature at each measuring point, data is collected synchronously at the same measuring point location when collecting the measured elevation values ​​for each measuring point on the main beam. Specifically, a patch-type temperature sensor can be temporarily placed next to the leveling rod, or a handheld infrared thermometer can be used to aim at the bridge deck or beam surface near the measuring point. This local temperature value is only used to correct the theoretical elevation value for that measuring point. When subsequently correcting the theoretical elevation value, the measured ambient temperature value used should be the local ambient temperature value for the corresponding measuring point, because different parts of the main beam may be affected by factors such as sunlight shadows and concrete hydration heat, resulting in temperature gradients. Using the local temperature value accurately reflects the actual thermal deformation at that point. However, when correcting the theoretical cable force values ​​for each cable, the measured ambient temperature value used is the global ambient temperature value. This is because the stay cables are exposed to the air and are quite long, so their overall temperature is mainly determined by the atmospheric temperature, making it more reasonable to use a global average value.

[0024] In this embodiment, local temperature and global temperature are clearly distinguished and used for correction of different objects, so that the elevation correction is more in line with the actual thermal expansion of each measuring point, and the cable force correction reflects the average temperature effect of the entire cable length, thereby significantly improving the accuracy of deviation calculation.

[0025] In one embodiment, to obtain more accurate theoretical values, a parametric inversion technique is used to correct the computational model. First, an initial finite element model of the cable-stayed bridge is established, for example, using beam elements to simulate the main girder and bridge towers, and cable elements to simulate the stay cables. This initial model includes three parameters that need correction: the bending stiffness of the main girder (usually input as the elastic modulus multiplied by the moment of inertia of the section), the elastic modulus of the stay cables, and the self-weight intensity of the main girder (i.e., self-weight per meter). There are often deviations between the design and actual values ​​of these parameters. For example, the actual elastic modulus of concrete may be 5% to 10% lower than the design value, the elastic modulus of the cables may be lower due to wire twisting, and the actual unit weight and cross-sectional dimensions of the main girder may also differ from the design. Measured data from at least two construction stages that have completed tensioning prior to the current construction stage are obtained. For example, the first two or three construction stages can be selected, with data for each stage including the measured elevation values ​​of each measuring point on the main girder and the measured cable force values ​​of each stay cable. The theoretical values ​​output by the computational models corresponding to these completed construction stages (i.e., the elevation and cable force calculated by the initial model) are used as target values. The three parameters to be corrected are then retrieved and corrected using a least squares optimization algorithm or a Kalman filter algorithm. Taking least squares optimization as an example, the objective function is constructed as follows: For each completed construction stage, the sum of squares of the elevation calculation errors (theoretical value minus measured value) at all measuring points is calculated, plus the sum of squares of the cable force calculation errors at all stay cables. These two sums are then added together to obtain the total sum of squared errors. The values ​​of the parameters to be corrected are adjusted to minimize this total sum of squared errors. Gradient descent or genetic algorithms can be used for optimization. After finding the optimal parameters, they are substituted into the computational model to obtain the corrected computational model. Then, using this corrected model, the theoretical elevation values ​​of each measuring point on the main beam and the theoretical cable force values ​​of each stay cable in the current construction stage are recalculated. These theoretical values ​​are closer to the actual values ​​because they have already considered the stiffness characteristics of the actual structure in the early stages.

[0026] In this embodiment, by using measured data from the early construction phase to invert and correct the key parameters of the model, the calculation model gradually approximates the mechanical behavior of the actual structure, thereby improving the prediction accuracy of theoretical values ​​in the current and subsequent construction phases and fundamentally reducing the sources of systematic errors.

[0027] In one embodiment, the specific calculation process for correcting the theoretical elevation values ​​of each measuring point on the main beam is as follows. The original theoretical elevation value is denoted as H0, which is based on a reference temperature T in the design drawings and construction simulation. 基准 (For example, optionally 20 degrees Celsius or 25 degrees Celsius) Calculated. The actual measured value of the local ambient temperature at this measuring point is T_local. The linear expansion coefficient of the main beam material is denoted as α. 梁 For concrete, 1.0 × 10 can be used. -5 / ℃, for steel, we can take 1.2×10 -5 / ℃. Then the corrected theoretical elevation value H corrected =H0×[1+α 梁 ×(T 局部 -T 基准 For example, H0 is 10 meters, α 梁 It is 1.0e-5, T 局部 If the temperature is 30 degrees Celsius and the reference temperature (T) is 20 degrees Celsius, then the temperature difference is 10 degrees Celsius, the correction factor is 1.0001, and the corrected elevation is 10.001 meters. The specific calculation formula for correcting the theoretical values ​​of the cable forces of each cable is: Corrected theoretical cable force F corrected =F0+β×α 索 ×(T_ 全局 -T 基准 )×E 索 ×A 索 Where F0 is the theoretical value of the original cable force, and α 索 This is the coefficient of linear expansion of the cable-stayed bridge material, which can be taken as 1.2 × 10⁻⁶. -5 / ℃, T 全局 This is the measured value of the global ambient temperature, E 索 This is the elastic modulus of the stay cable, for example, it can be taken as 1.95 × 10⁻⁶. 5 MPa, A 索 β is the cross-sectional area of ​​the stay cable, which can be measured. β is the cable force temperature sensitivity coefficient, a dimensionless coefficient that reflects the efficiency of cable force change caused by temperature variations. Its value can range from 0.8 to 1.2, for example, 0.9, 1.0, or 1.1. This coefficient can be determined through finite element sensitivity analysis or field calibration tests. The physical meaning of this formula is: temperature changes cause changes in the free thermal expansion length of the stay cable, but in a statically indeterminate structure, this deformation is constrained, thus generating additional internal forces. β is used to correct the proportional relationship between the theoretically calculated value and the actual internal force.

[0028] In existing technologies, the temperature correction for the theoretical value of cable force is often simply applied using the same multiplicative form as the elevation, i.e., F corrected = F0×(1+α 索 The formula (×ΔT) does not conform to the principles of mechanics because the relationship between cable force and temperature is not a simple direct proportionality. This embodiment adopts an additive correction formula and introduces a temperature sensitivity coefficient β, which can more accurately describe the influence mechanism of temperature change on cable force in statically indeterminate structures, making the corrected theoretical value of cable force closer to the actual situation.

[0029] In one embodiment, the first and second thresholds are set dynamically and adaptively, rather than as fixed constants. The specific steps are as follows: Obtain the absolute values ​​of the elevation deviations of all measuring points on the main beam in at least three construction stages that have completed tensioning prior to the current construction stage. For example, the first three or four construction stages can be selected, each with multiple measuring points. Collect all these absolute values ​​to obtain a dataset. Calculate the arithmetic mean of this dataset, denoted as μ1, and then calculate its standard deviation, denoted as σ1. Then set the first threshold as μ1 + 2 × σ1. Simultaneously, to ensure the threshold is within a reasonable range for the project, upper and lower limits are added: the first threshold can be no less than 3 mm and no more than 30 mm. For example, if the calculated μ1 + 2σ1 is 2 mm, then 3 mm is used; if the calculated value is 35 mm, then 30 mm is used. For the second threshold, obtain the absolute values ​​of the cable force deviations of all stay cables in the same set of historical construction stages, and similarly calculate their arithmetic mean μ2 and standard deviation σ2. Then the second threshold is μ2 + 2 × σ2. Meanwhile, the second threshold can be no less than 2% and no more than 15% of the design cable force. For example, if the design cable force is 1000kN, the second threshold should be no less than 20kN and no more than 150kN. If the calculated μ² + 2σ² is 10kN, but 10kN is less than 20kN, then 20kN is used; if the calculated value is 200kN, then 150kN is used. This threshold setting is statistically significant: under the assumption of a normal distribution, approximately 95% of the normal deviation will fall within the range of μ ± 2σ. Deviations exceeding this range are considered outliers and should be adjusted. Moreover, the threshold will be dynamically updated as construction progresses. When the deviation fluctuates greatly in the early stages, the threshold will automatically widen; when the construction quality improves and the deviation decreases in the later stages, the threshold will automatically tighten. It should be noted that obtaining data from at least three previous tensioned cable-stay ... If there are fewer than three completed construction phases prior to the current construction phase (e.g., the first and second construction phases), the mean and standard deviation cannot be calculated. In this case, preset initial thresholds can be used as the first and second thresholds. For example, the first threshold can be preset to 5mm, and the second threshold can be preset to 5% of the design cable force value. After accumulating data from three construction phases, the system will automatically switch to a dynamic adaptive threshold calculation method.

[0030] This embodiment dynamically adjusts the threshold based on the statistical characteristics of historical deviations, so that the control judgment criteria are adapted to the actual quality control level of the current construction stage. This avoids ineffective adjustments caused by overly strict thresholds and prevents the accumulation of deviations caused by overly lenient thresholds.

[0031] In one embodiment, the specific implementation of solving the cable force adjustment based on the influence matrix method is as follows: First, an initial influence matrix M0 is established, with dimensions of n rows and m columns, where n is the total number of measuring points on the main beam and m is the total number of stay cables. The elements m in M0... ij This represents the influence of the unit cable force change (kN) of the j-th stay cable on the elevation of the i-th main beam measuring point, in mm. Then, the actual cable force adjustment vector ΔF from all completed construction stages prior to the current construction stage is obtained. actual This is an m-dimensional vector, where each element represents the increase in cable force during actual adjustment (negative values ​​indicate release). Simultaneously, the vector of actual elevation changes ΔH corresponding to these adjustments is obtained. actual This is an n-dimensional vector, where each element represents the elevation difference of the corresponding measuring point before and after the actual adjustment. The initial influence matrix M0 is corrected online using a recursive least squares algorithm to obtain the current influence matrix M. The basic formula for recursive least squares is: M k = M k -1+ K k ×(Δ H k - M k−1 ×Δ F k ), where K k The gain matrix is ​​calculated recursively from the covariance matrix. M is updated each time a new set of adjustment data is obtained, gradually approximating the true influence relationship. With the current influence matrix M, the cable tension adjustment ΔF for each stay cable is then used. j Let (j=1,...,m) be the unknown variables. Establish a quadratic programming model with inequality constraints. The objective function is as follows: The first term sums the values ​​at all measuring points i on the main beam, with weights w. i Multiply by the target elevation H (in parentheses) i target Subtract the current measured elevation H i current Then subtract the square of the sum of all cable tension adjustments multiplied by their influence coefficients. Where the weight w... i The importance of each measuring point can be set; for example, the weight of the mid-span measuring point can be 2, and other measuring points can be 1. The second term is a penalty term, which is λ multiplied by the sum of the squares of all cable force adjustments. λ is the penalty coefficient, which can be 0.01 or 0.1, used to suppress excessive adjustment amounts and avoid sudden changes in cable force. The constraints are: For each stay cable j, the adjusted cable force (i.e., the current measured cable force F) j measured Add ΔFj The cable tension must be between 0.8 times the design cable force F. j design The adjusted cable force is between 1.0 times the design cable force. The design cable force value is given in the design drawings. This constraint ensures that the adjusted cable force does not exceed the upper limit of the design and is not lower than 80% of the design value, preventing the cable force from being too loose or too tight. Solving this quadratic programming model can be done using a numerical optimization library, such as optionally using OSQP (an open-source quadratic programming solver) or MATLAB's quadprog function. The inputs are the coefficient matrix H and vector f of the objective function, as well as the constraint matrix A and the upper and lower bound vectors lb and ub, to obtain the optimal ΔF. j vector.

[0032] This embodiment uses recursive least squares to correct the influence matrix online, enabling the matrix to reflect the actual evolution of structural stiffness; by introducing weights and penalty terms, it suppresses excessive adjustment while approximating the target linear shape; and by using inequality constraints, it ensures that the cable force does not exceed the design safety range, thus obtaining an adjustment scheme that is both effective and safe.

[0033] In one embodiment, the initial influence matrix M0 is established as follows: In the initial calculation model of the current construction stage (i.e., the original finite element model without parameter inversion correction), a unit cable force is applied to each stay cable, while keeping the cable forces of all other stay cables unchanged. The magnitude of the unit cable force can be chosen as 1 kN, or 10 kN for numerical stability. The application method is to increase the initial strain or initial tension of the j-th stay cable by a corresponding amount in the finite element software. Then, a linear static analysis is run to extract the vertical displacement (i.e., elevation change) of each main beam measuring point under the action of only this unit cable force. Specifically, for the j-th stay cable, the displacement values ​​of all n measuring points are calculated, where the displacement value of the i-th measuring point is m. ij The above operation is repeated sequentially for j=1,2,...,m, changing only the cable force of one cable each time while keeping the others unchanged, thus obtaining a complete m column vector. These column vectors are then arranged in order to form an n x m matrix, which is the initial influence matrix M0. Each column of this matrix corresponds to the influence of a unit cable force of one cable, and each row corresponds to the response of a measuring point. In subsequent online corrections, this M0 serves as the initial value M0 for the recursive least squares algorithm.

[0034] In existing technologies, influence coefficients are sometimes estimated using empirical formulas, such as rough estimates based on cable spacing and beam stiffness, or by completely ignoring the coupling effect of cable force changes on elevation, leading to inaccurate adjustment amounts. This embodiment uses the unit cable force loading method in the finite element model to clearly define and accurately calculate each influence coefficient, giving the initial influence matrix a clear mechanical meaning and a reliable computational basis, providing an accurate starting point for subsequent online corrections.

[0035] In one embodiment, the following refined steps are employed to ensure safety and effectiveness when performing cable tension adjustment operations. First, all stay cables requiring adjustment are sorted from largest to smallest absolute value of their tension adjustment. This is because cables with larger adjustment amounts have a more significant impact on the main beam alignment, and prioritizing their adjustment improves efficiency. For example, if two cables have adjustment amounts of +50kN and -20kN respectively, the +50kN cable is adjusted first. For each stay cable requiring adjustment, its tension adjustment is implemented progressively in three levels: level one is 20% of the target adjustment, level two is 30%, and level three is 50%. For example, if the target adjustment is +100kN, then level one tensioning is 20kN, level two is 30kN, and level three is 50kN. After each stage of tensioning or releasing is completed, the operation is immediately paused. The same method as before is used to re-collect the measured elevation values ​​of each measuring point on the main beam and the measured cable force values ​​of each stay cable at the current stage. Then, the correction and deviation judgment steps are repeated, followed by the influence matrix method to update the calculation of the remaining cable force adjustments. This is because during the staged adjustment process, the structural response may exhibit nonlinearity, and there may be coupling effects between adjacent cables, requiring correction of subsequent adjustments based on measured feedback. When both stay cables on both sides of the same bridge tower (e.g., the left and right cables) need adjustment, or when adjustments are needed at the same symmetrical location (e.g., the corresponding numbered stay cables on both sides of the bridge tower), a synchronous symmetrical tensioning or releasing method is adopted. That is, two jacks are started simultaneously, applying the same adjustment value (same or opposite signs depending on the actual situation) to the stay cables on both sides. The synchronization time difference between the two sides can be controlled to no more than 2 seconds. This can be achieved by setting a synchronization controller or using the same hydraulic pump station for flow distribution. This ensures the bridge tower is under stress balance and avoids excessive unbalanced bending moments. During the adjustment process, it is necessary to monitor the cable force changes of the two adjacent stay cables to the currently adjusted stay cable in real time. "Adjacent" refers to the two cables spatially closest to the current cable, such as cables numbered j-1 and j+1 on the same side of the bridge tower. Monitoring can be achieved by installing cable force sensors on these adjacent cables and displaying the data in real time through a data acquisition system. If the cable force change of an adjacent stay cable exceeds 1% of its design cable force value, the current adjustment operation is immediately paused. The cable force change of the adjacent stay cables is then used as an additional input to re-execute the influence matrix method solution in claim 6, updating the cable force adjustment amounts of the current stay cable and its adjacent stay cables. The adjustment then continues according to the updated adjustment amounts. For example, if the design cable force is 1000kN, 1% is 10kN. If the change in adjacent cables exceeds 10kN, a re-solution is triggered.

[0036] In existing technologies, cable tension adjustment often involves a single, unstaged tensioning process without considering grading, sequencing, or synchronization with adjacent cables. This can easily lead to significant nonlinear deformation during adjustment, or sudden changes in the cable tension of adjacent cables exceeding safe limits. This embodiment, through sequencing, grading, synchronous symmetrical operation, and real-time monitoring of adjacent cable tensions, makes the adjustment process more precise and controllable. It can promptly detect and correct coupling effects during adjustment, avoiding the generation of new additional internal forces and alignment deviations, thus improving the safety of construction adjustments and the accuracy of the final bridge structure.

[0037] In one embodiment, before completing the adjustment and preparing to enter the next construction stage, a verification and iterative convergence step is added to ensure that the adjustment effect truly meets the requirements. Specifically, after executing S5 (i.e., completing the tensioning or releasing operation according to the cable force adjustment amount), or when the deviation is determined not to exceed the standard in S4 and preparations are made to skip the adjustment and enter the next stage, the next stage is not immediately initiated. Instead, the measured elevation values ​​of each measuring point on the main beam and the measured cable force values ​​of each stay cable are re-collected for the current construction stage. The data collection method is exactly the same as in S1. Then, S2 to S4 are repeated, i.e., temperature correction, deviation calculation, and threshold judgment are performed again. If the absolute values ​​of the recalculated elevation deviations of all measuring points on the main beam are not greater than the first threshold, and the absolute values ​​of the cable force deviations of all stay cables are not greater than the second threshold, then the control state is confirmed to meet the requirements, and the next construction stage is officially entered. If any deviation still exceeds the standard, S4 and S5 are repeated, i.e., the cable force adjustment amount is recalculated, and the tensioning or releasing operation is performed according to the new adjustment amount. This cycle continues until the conditions are met. To prevent infinite loops under abnormal conditions (such as sensor failure or large nonlinear deformation of the structure), a maximum number of iterations can be preset, for example, optionally set to 3 or 5 times. If, after reaching the maximum number of iterations, the deviation still exceeds the limit after reassessment, the system issues a warning signal, such as displaying red warning text on the monitoring computer screen, simultaneously emitting a buzzer and flashing lights via an audible and visual alarm, and automatically stopping further tensioning operations, awaiting manual intervention to investigate the cause. This maximum number of iterations can be preset based on construction experience or set as a modifiable parameter in the control program. This embodiment forms a closed-loop verification mechanism through adjusted re-acquisition and reassessment, ensuring that each adjustment effectively controls the deviation within the allowable range. Simultaneously, setting the maximum number of iterations and the stop warning mechanism prevents the control system from entering an infinite loop under abnormal conditions, ensuring construction safety and the terminateability of the control process.

[0038] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A construction control method for cable-stayed bridges, characterized in that, include: S1: During the construction phase of each tensioned cable of the cable-stayed bridge, collect the measured elevation values ​​of each measuring point on the main beam, the measured cable force of each cable, and the measured ambient temperature of the current phase. S2: Based on the design drawings and construction simulation calculations, obtain the theoretical elevation values ​​of each measuring point of the main beam and the theoretical cable force values ​​of each stay cable in the current construction stage. Using the linear expansion coefficient of the structural materials, and based on the difference between the measured ambient temperature and the preset reference temperature value, correct the theoretical elevation values ​​of each measuring point of the main beam and the theoretical cable force values ​​of each stay cable to obtain the corrected theoretical elevation values ​​of each measuring point of the main beam and the corrected theoretical cable force values ​​of each stay cable. S3: Calculate the elevation deviation of each measuring point on the main beam. The elevation deviation is equal to the measured elevation of each measuring point on the main beam minus the corrected theoretical elevation of each measuring point on the main beam. Calculate the cable force deviation of each stay cable. The cable force deviation is equal to the measured cable force of each stay cable minus the corrected theoretical cable force of each stay cable. S4: When the absolute value of the elevation deviation of any main beam measuring point is greater than the first threshold or the absolute value of the cable force deviation of any cable is greater than the second threshold, the cable force adjustment of each cable is calculated based on the influence matrix method, and S5 is executed; otherwise, proceed directly to the next construction stage. S5: Tension or release the corresponding stay cables according to the cable tension adjustment amount, and then proceed to the next construction stage.

2. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, In S1, the magnetic flux sensor or vibrating wire pressure ring installed at the anchor end of the cable is used for measurement. The sampling frequency is not less than 1Hz, and the average value of the measurement data is taken as the actual measured value of the cable force of the cable. The global ambient temperature was measured by simultaneously collecting and averaging the data from temperature sensors installed in at least three louvered boxes at the bridge tower, mid-span of the main beam, and both ends. The local ambient temperature at each measuring point was measured simultaneously at the same measuring point location when collecting the elevation values ​​of each measuring point on the main beam. The measured ambient temperature values ​​used in S2 to correct the theoretical elevation values ​​of each measuring point on the main beam are the local ambient temperature values ​​of the corresponding measuring points; the measured ambient temperature values ​​used to correct the theoretical values ​​of the cable forces of each stay cable are the global ambient temperature values.

3. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, An initial calculation model is established, which includes the bending stiffness of the main beam, the elastic modulus of the stay cables, and the self-weight intensity of the main beam as parameters to be corrected. Obtain measured data from at least two pre-tensioned cable-stayed construction phases prior to the current construction phase. The measured data includes the measured elevation values ​​of each measuring point on the main beam and the measured cable force values ​​of each cable in the pre-tensioned cable-stayed construction phases. Using the theoretical elevation values ​​of each measuring point on the main beam and the theoretical cable force values ​​of each cable corresponding to the construction stage of the tensioned cable stays as the objectives, the least squares optimization or Kalman filter algorithm is used to inversely correct the parameters to be corrected, so that the sum of the squares of the elevation calculation error and the sum of the squares of the cable force calculation error in the construction stage of the tensioned cable stays is minimized after correction. Using the revised calculation model, the theoretical elevation values ​​of each measuring point on the main beam and the theoretical cable force values ​​of each stay cable are calculated at the current construction stage.

4. The construction control method for cable-stayed bridges as described in claim 3, characterized in that, The linear expansion coefficient of the main beam material is used, and corrections are made based on the difference between the measured local ambient temperature at the measuring point and the preset reference temperature. The corrected theoretical elevation value = original theoretical elevation value × [1 + α] 梁 ×(T 局部 -T 基准 )], where α 梁 The coefficient of linear expansion of the main beam material, T 局部 T represents the measured local ambient temperature at this measuring point. 基准 This is the preset reference temperature value; The linear expansion coefficient of the cable-stayed bridge material is used, and corrections are made based on the difference between the measured global ambient temperature and the preset reference temperature. The corrected theoretical cable force is calculated as: Original theoretical cable force + β × α 索 ×(T 全局 -T 基准 )×E 索 ×A 索 , where α 索 T is the coefficient of linear expansion of the cable-stayed bridge material. 全局 The measured global ambient temperature is given, β is the cable temperature sensitivity coefficient, ranging from 0.8 to 1.2, and E... 索 Let A be the elastic modulus of the stay cable. 索 This represents the cross-sectional area of ​​the stay cable.

5. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, The first and second thresholds are set as follows: Obtain the absolute values ​​of the elevation deviations of all measuring points of the main beam in at least three construction stages with tensioned cable stays prior to the current construction stage, calculate the first average value and the first standard deviation, and set the first threshold as the first average value + 2 × the first standard deviation, which shall be no less than 3 mm and no more than 30 mm. Obtain the absolute values ​​of the cable force deviations of all stay cables in at least three pre-tensioned cable-stayed construction stages prior to the current construction stage, calculate the second average value and the second standard deviation, and set the second threshold as the second average value + 2 × the second standard deviation, which shall be no less than 2% of the design cable force value of the stay cable and no more than 15% of the design cable force value of the stay cable.

6. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, Establish an initial influence matrix M0, where m is an element of the initial influence matrix M0. ij This represents the influence coefficient of the unit cable force change of the j-th cable on the elevation of the i-th main beam measuring point; Obtain the actual cable force adjustment vector ΔF for all tensioned stay cables completed in the construction phases prior to the current construction phase. actual With the corresponding actual change vector of elevation ΔH actual The initial influence matrix M0 is corrected online using a recursive least squares algorithm to obtain the current influence matrix M; The cable tension adjustment ΔF of each cable j For unknown variables, the following quadratic programming model with inequality constraints is established; The objective function is: The constraints are: ； Among them, H i target H is the corrected theoretical elevation value of the i-th main beam measuring point. i current w is the measured elevation value of the i-th main beam measuring point. i λ is the weighting coefficient for the i-th main beam measuring point, λ is the penalty coefficient for cable force adjustment, and F j design Let F be the design cable force value of the j-th stay cable. j measured Let be the measured cable force of the j-th stay cable, n be the total number of measuring points on the main girder, and m be the total number of stay cables; solve the quadratic programming model to obtain the cable force adjustment ΔF for each stay cable. j .

7. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, In the initial calculation model of the current construction phase, a unit cable force is applied to each stay cable while keeping the cable forces of other stay cables constant. The elevation change of each main beam measuring point is extracted, and the elevation change of the i-th main beam measuring point caused by the unit cable force of the j-th stay cable is taken as element m in the initial influence matrix. ij .

8. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, In S5, the stay cables that need to be adjusted are sorted from largest to smallest according to the absolute value of the cable tension adjustment, and the stay cables with the largest absolute value of the cable tension adjustment are adjusted first. For each cable that needs adjustment, the cable tension adjustment is divided into three levels: the first level is 20% of the target adjustment, the second level is 30%, and the third level is 50%. After each level of tensioning or releasing is completed, the current stage of the main beam's measured elevation values ​​and the cable tension values ​​of each cable are collected again. Then, S2 to S4 are executed again to update and calculate the remaining cable tension adjustment. When the stay cables on both sides of the same bridge tower or at the same symmetrical position need to be adjusted, a synchronous symmetrical tensioning or releasing method shall be adopted, and the synchronous time difference between the adjustments on both sides shall not exceed two seconds. During the adjustment process, the changes in cable force of the two cables adjacent to the currently adjusted cable are monitored in real time. If the change in cable force of the adjacent cable exceeds one percent of its design cable force value, the current adjustment is paused, and the change in cable force of the adjacent cable is used as an additional input to re-execute the influence matrix method in S4 to solve the problem. After updating the cable force adjustment of the current cable and its adjacent cables, the adjustment continues.

9. The construction control method for cable-stayed bridges as described in claim 1, characterized in that, Before proceeding to the next construction phase, the following is also included: Re-collect the measured elevation values ​​of each measuring point on the main beam and the measured cable force values ​​of each stay cable during the current construction phase, and repeat steps S2 to S4. If the absolute values ​​of the elevation deviations of all measuring points of the main beams obtained by recalculation are not greater than the first threshold, and the absolute values ​​of the cable force deviations of all stay cables are not greater than the second threshold, then proceed to the next construction stage. Otherwise, repeat steps S4-S5, performing tensioning or releasing operations according to the updated cable force adjustment, until the above conditions are met or the preset maximum number of iterations is reached; if the maximum number of iterations is reached but the conditions are still not met, issue a warning and stop construction.

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