Method for synchronous tensioning and precision control of complex spatial cable-strut and membrane structure

Abstract

The application provides a complex space cable truss and membrane structure synchronous tensioning and precision control method, comprising: establishing a cable truss and membrane structure coupling nonlinear finite element analysis model, determining construction target; measurement and control system layout and initialization; starting initial tensioning; real-time state monitoring and data processing; intelligent analysis and decision instruction generation; collaborative tensioning execution; real-time safety monitoring; iteration judgment and stage promotion; completion acceptance. Through closed-loop feedback and intelligent algorithm, the application realizes sub-millimeter level accurate control of complex cable membrane structure form and prestress, automatic tensioning and intelligent decision significantly reduces manual intervention and trial and error time, shortens construction period, real-time monitoring and early warning mechanism can discover and handle potential risks in time, avoids over-tensioning or instability, tensioning accurate control can reduce material waste, optimizes equipment use, and detailed data record can provide basis for engineering acceptance and later operation and maintenance.

Description

Technical Field

[0001] This invention belongs to the field of construction technology for large-span spatial structures, and particularly relates to a method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures. Background Technology

[0002] Large-span cable-stayed trusses and membrane structures are widely used in large public buildings such as stadiums, convention centers, and transportation hubs due to their advantages of being lightweight, high-strength, aesthetically pleasing, and having good light transmission. These structures are mostly prestressed, and their final shape and internal force distribution are highly dependent on the precise tensioning process. The tensioning of the cable truss directly affects the boundary conditions of the membrane structure, while the tensioning of the membrane structure, in turn, has a significant coupling effect on the internal forces and displacements of the cable truss. This strong nonlinear coupling makes the synchronous tensioning of cable-membrane structures a highly challenging technical problem. Traditional tensioning methods (such as manual point-by-point control and batch-by-region tensioning) often face many bottlenecks when dealing with complex cable-membrane systems, including difficulties in synchronous coordination, inaccurate handling of nonlinear and coupling effects, insufficient real-time status monitoring and feedback, and difficulty in guaranteeing tensioning accuracy and forming control. These bottlenecks can lead to localized stress concentration, wrinkling, or even instability, affecting structural safety and project quality. To address the shortcomings of existing technologies, this invention aims to provide a method that can effectively solve the problems of coupling, multi-point coordination, and high-precision control during the integrated synchronous tensioning of spatial cable-stayed trusses and membrane structures. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures. Through intelligent closed-loop control, it achieves precise, efficient, and safe management of the tensioning construction process of complex cable-membrane structures, thereby accurately controlling the formation and prestress distribution of the structure.

[0004] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0005] A method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures includes the following process:

[0006] S1: Model building and objective definition;

[0007] S2: Deployment and initialization of the measurement and control system;

[0008] S3: Initiate initial tensioning;

[0009] S4: Real-time status monitoring and data processing;

[0010] S5: Intelligent analysis and decision command generation;

[0011] S6: Collaborative tensioning execution;

[0012] S7: Real-time security monitoring;

[0013] S8: Iterative judgment and phase advancement;

[0014] S9: Final acceptance.

[0015] Furthermore, S1 includes: establishing a coupled nonlinear finite element analysis model of the cable truss and membrane structure, and determining the structural morphology, cable force distribution, and membrane stress distribution under the final target tension state according to design requirements; at the same time, setting graded loading targets and control accuracy requirements for each stage of tension.

[0016] Furthermore, S2 includes: deploying a sensor network at key locations in the cable truss and membrane structure system to collect multi-point three-dimensional displacement, cable force of key cable segments and environmental parameters of the structure in real time and with high precision during the tensioning process; deploying multiple automated tensioning devices at key tensioning points of the structure; and calibrating all sensors and automated tensioning devices.

[0017] Configure a central control processing unit, install data acquisition cards and control algorithm software to form a central control software system, establish a sensor network and data communication between the automated tensioning equipment and the central control software system, and set initial tensioning control parameters, tensioning sequence, tensioning targets and safety thresholds for each stage; the control algorithm software includes a model predictive control core module, a finite element model online calibration and update module, a multi-point collaborative and synchronous control logic module, and a safety monitoring and emergency handling logic module.

[0018] Furthermore, S3 includes: the central control software system issuing first-stage tensioning commands to each automated tensioning device based on the set initial tensioning parameters and sequence, or the initial loading path obtained from the preliminary open-loop prediction analysis of the finite element model.

[0019] Furthermore, S4 includes: during the tensioning adjustment process and each adjustment interval, the sensor network collects multi-point three-dimensional displacement, cable force, membrane surface state and environmental parameter data of the structure in real time, and transmits the collected multi-source heterogeneous data to the central control processing unit for preprocessing, time synchronization, coordinate transformation and data fusion to form a unified real-time structural status dataset.

[0020] Furthermore, S5 includes: the central control processing unit comparing the real-time status dataset with the preset tensioning target for this stage and evaluating the deviation; based on the difference between the measured data and the finite element model prediction, performing online calibration or status update of the key parameters of the finite element model; and using the updated finite element model and optimized control algorithm, comprehensively considering structural nonlinearity, cable-membrane coupling effect, current deviation, and various safety and equipment constraints, calculating the optimal coordinated tensioning increment command vector for all tensioning points that can most effectively bring the structural state closer to the next target state.

[0021] Furthermore, S6 includes: the central control processing unit transmits the generated tensioning increment command vector to the local controller unit of each automated tensioning device, and each local controller unit drives the tensioning actuator connected to it to perform corresponding loading, unloading, elongation or retraction operations according to the received command and the specific increment value.

[0022] Furthermore, S7 includes: throughout the tensioning process, the safety monitoring module inside the central control processing unit monitors the key safety indicators of the structure in real time, including the maximum cable force, the maximum displacement of the nodes, and the maximum stress on the membrane surface. If any indicator approaches or exceeds the preset safety threshold, the tensioning is automatically paused, an alarm is triggered, and an emergency adjustment or unloading operation is performed according to the contingency plan.

[0023] Furthermore, S8 includes: repeating S4 to S7, iteratively adjusting through closed-loop feedback until the structural state reaches the control target and accuracy requirements of the current tensioning stage, and then entering the next tensioning stage; if it is the last stage, then until the final target tensioning state is reached.

[0024] Furthermore, S9 includes: after all tensioning stages are completed, a verification measurement of the overall final shape of the structure and a comprehensive test of the internal cable force and membrane surface stress are carried out. After confirming that the design requirements are met, a construction process and result report is generated.

[0025] The present invention has the following beneficial effects:

[0026] Through closed-loop feedback and intelligent algorithms, sub-millimeter-level precise control of complex cable-membrane structure morphology and prestressing is achieved; automated tensioning and intelligent decision-making significantly reduce manual intervention and trial-and-error time, shortening the construction cycle; real-time monitoring and early warning mechanisms can promptly detect and address potential risks, avoiding over-tensioning or instability; precise control reduces material waste and optimizes equipment use; detailed data records provide a basis for project acceptance and subsequent operation and maintenance. Attached Figure Description

[0027] Figure 1 This is an overall flowchart of the method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures described in this invention;

[0028] Figure 2 This is a schematic diagram of the core process of closed-loop iterative tension control.

[0029] Figure 3 This is a schematic diagram of the intelligent analysis and decision-making process. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] The method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures described in this invention is as follows: Figure 1 , 2 As shown in Figure 3, the specific process includes the following:

[0032] S1: Model building and objective definition;

[0033] A precise coupled nonlinear finite element analysis (FEM) model of the cable truss and membrane structure is constructed using professional structural analysis and design software. This model includes all cable elements, membrane elements, and related support structures. Cable elements include edge cables, ridge cables, valley cables, stabilizing cables, and tension cables, and must be assigned actual cross-sectional properties, material properties, and initial relaxation lengths. Membrane elements consider their orthotropic material properties, wrinkling behavior, and detailed material parameters such as longitudinal and latitudinal elastic modulus, shear modulus, thickness, and density. Subsequently, the connection methods between the various structural components (such as cable-cable node plates, cable-membrane clamps, and cable / membrane-support anchorages, which can employ shared nodes, rigid connections, spring elements, or contact elements) and quasi-connections are accurately simulated. First, establish clear boundary conditions. Then, based on detailed design drawings and structural calculations, clearly define the final target state that the structure should achieve after tensioning construction, including the three-dimensional coordinates of all key structural nodes and the target prestress values ​​of all main load-bearing cable segments, as well as the possible target stress level of the membrane surface. Next, decompose the complex overall tensioning process into several controllable main tensioning stages. Each stage is planned to apply a portion of the total prestress, and the intermediate form and internal force targets to be achieved at the end of each stage are clearly defined. At the same time, set clear control accuracy requirements for each stage or the final completed state, such as the key cable force error not exceeding ±2% of the target value and the key node spatial displacement error not exceeding ±5mm.

[0034] S2: Deployment and initialization of the measurement and control system;

[0035] At key nodes of the cable truss and on the surface of the membrane structure, special attention is paid to areas with drastic curvature changes, high expected stress, or susceptibility to wrinkling. High-contrast optical monitoring targets are deployed at a predetermined density, and multiple high-resolution industrial cameras are installed and precisely calibrated to form a digital image correlation (DIC) system, ensuring that its field of view completely covers all monitoring targets and provides sub-millimeter-level real-time three-dimensional coordinate measurement capabilities. Subsequently, calibrated high-precision cable force sensors (such as through-hole pressure sensors and vibrating wire cable force gauges) are installed on all key cable segments involved in active tensioning and other major cable segments that significantly affect the overall stress state of the structure. Then, weather stations or independent temperature sensors and anemometers are installed at representative locations on the construction site to record environmental conditions in real time. Next, independently and precisely controlled automated tensioning equipment, such as electro-hydraulic jacks equipped with high-precision displacement and pressure sensors, is installed at all cable end anchoring points or membrane edge tensioning mechanisms where active tensioning is planned. Finally, all installed sensors and tensioning actuators undergo rigorous laboratory calibration and on-site recalibration.

[0036] Establish a stable and accurate global three-dimensional coordinate system at the construction site, and accurately transform the coordinate systems of all monitoring devices to this global coordinate system through measurement methods. Then, configure a central control processing unit (such as a high-performance industrial computer or PXIe embedded controller with a CPU frequency of no less than 3GHz and memory of no less than 16GB), install a data acquisition card (supporting multi-channel synchronous acquisition with a sampling rate that meets requirements) and control algorithm software to form a central control software system. After completing these hardware and software configurations, input the previously determined tensioning target values ​​for each stage, the allowable control accuracy range, the initial tensioning sequence or coordinated loading ratio (e.g., main cables are tensioned synchronously in groups, with coordination between groups according to a ratio) and the early warning thresholds (e.g., cable force reaches 85% of the design value, displacement deviation reaches 70% of the allowable value) and alarm thresholds (e.g., cable force reaches 95% of the design value, displacement deviation reaches 90% of the allowable value) into the central control software system.

[0037] The control algorithm software includes a core module for Model Predictive Control (MPC) to implement the key functions of the entire intelligent control system. This module, based on a current high-fidelity nonlinear finite element model (as the prediction model), solves a finite-time open-loop optimization problem through rolling optimization in each control cycle to find the tension increment sequence that optimally approximates the target state while satisfying all constraints. Its implementation relies on an efficient prediction model interface (using model reduction techniques or machine learning surrogate models to accelerate the prediction of complex models), an embedded or invoked nonlinear programming (NLP) solver based on the SQP algorithm, and the ability to explicitly handle various constraints and provide a parameter tuning interface (for adjusting the prediction time domain, control time domain, weighting factors, etc.). Simultaneously, the software integrates an online finite element model calibration and update module to address situations where the measured structural response deviates significantly from the model prediction. When the model is not in good working order, parameter sensitivity analysis and parameter estimation algorithms based on least squares and Gauss-Newton methods are used to dynamically adjust model parameters (such as the elastic modulus of the cable, the shear modulus of the membrane, and the boundary stiffness) to improve model fidelity. In addition, the software includes a multi-point collaborative and synchronous control logic module, which ensures that multiple tensioning devices operate precisely according to preset coordination relationships (synchronization, proportion, and sequence) through master-slave control, distributed consensus algorithms, path planning and interpolation algorithms, and event-driven logic. Finally, for the safety monitoring and emergency handling logic module, corresponding early warnings and alarms are triggered through real-time threshold comparison and logical judgment, and protective operations can be automatically executed according to preset emergency plans. The control algorithm software encapsulates these complex algorithms through modular design and runs them on the central control processing unit, which is tightly integrated with the data acquisition system, finite element analysis engine, and tensioning device control system.

[0038] S3: Initiate initial tensioning;

[0039] Based on the set initial tensioning parameters and sequence, or the initial loading path obtained from the preliminary open-loop prediction analysis of the finite element model, the central control software system issues the first-stage tensioning command to each automated tensioning device. This initial tensioning usually involves a small loading amount, aiming to eliminate the initial relaxation of the components, allow the structure to initially bear force, and test the collaborative working ability of the entire measurement and control system.

[0040] S4: Real-time status monitoring and data processing;

[0041] During each minute incremental loading / unloading action of the tensioning equipment and the brief static balancing interval after each incremental adjustment step, all deployed sensor networks (data acquisition systems) continuously acquire high-frequency data. This includes the three-dimensional spatial coordinates of all optical target points calculated in real time by the DIC system, the stable cable force values ​​acquired and processed by the cable force sensors, parameters such as temperature and wind speed recorded by environmental sensors, and real-time travel and output force information fed back by the automated tensioning equipment's own sensors. Subsequently, all acquired raw data is transmitted in real time and synchronously to the central control processing unit through the data acquisition system. Within this unit, data cleaning and preprocessing (including noise filtering, outlier removal, and data validity verification), time synchronization and alignment, coordinate transformation and spatial registration, and possible multi-source data fusion are performed, ultimately forming a comprehensive and accurate description of the structure at the current moment. t k Digital state vector of the overall mechanical state X ( t k ), which is the real-time status dataset.

[0042] S5: Intelligent analysis and decision command generation;

[0043] The central control processing unit receives the real-time status dataset. X ( t k After that, the key state parameters are first precisely compared with the control target values ​​of the current tensioning stage to calculate the current deviation of each state parameter; then the real-time acquired state vector is... X ( t k The actual response of the structure is compared with the theoretical state X calculated under the same conditions using the current version of the finite element model. fem ( t kA detailed comparison is performed. If significant and systematic deviations are found, a model calibration procedure is triggered. Uncertain parameters in the FEM model (such as the effective elastic modulus of the cable, membrane shear stiffness, equivalent stiffness of boundary connections, initial geometric imperfections, etc.) are adjusted or model inputs (such as structural temperature) are directly updated through methods such as parameter identification / back analysis or direct state updates. This ensures that the calibrated FEM model more accurately reflects the true mechanical behavior of the structure. Subsequently, based on the current state deviation obtained from the evaluation, and using a high-fidelity nonlinear finite element model as a prediction tool, advanced optimization control algorithms such as Model Predictive Control (MPC) are employed. A finite-time open-loop optimization problem is solved through rolling optimization, ensuring that the predicted state of the structure approximates the reference trajectory in the optimal way while satisfying structural safety constraints, equipment capacity constraints, control quantity variation constraints, and multi-point coordination constraints. The optimal coordinated tensioning increment command vector to be applied to all automated tensioning points in the next step is calculated and output. This vector specifies in detail the specific force or displacement increment to be applied by each automated tensioning device in the next control step.

[0044] S6: Collaborative tensioning execution;

[0045] The calculated optimal coordinated tensioning increment command, containing the next actions of all automated tensioning points, is accurately and in real-time transmitted to the local controller units of each automated tensioning device via the control network. Subsequently, each local controller unit, based on the received command, its specified control mode (force control or displacement control), and the specific increment value, precisely drives its connected tensioning actuator to perform corresponding loading, unloading, extension, or retraction operations. A central control software system or distributed coordination mechanism ensures that the actions of all devices are synchronized in time or coordinated according to a preset ratio and sequence.

[0046] S7: Real-time security monitoring;

[0047] Throughout the entire closed-loop control cycle, at every stage and point in time, the safety monitoring module within the central control processing unit continuously and in real-time compares the key structural safety indicators collected from the sensor network (such as the current cable force of all cable segments, the current three-dimensional displacement of major nodes, and the current principal stress of representative membrane units) with preset safety thresholds. If an indicator reaches the warning threshold, the system will highlight it on the control interface and may issue an audible alert. If an indicator reaches the alarm / shutdown threshold, the system will immediately and automatically execute an emergency stop of all tensioning equipment, trigger audible and visual alarms, record and display over-limit information in detail, and may automatically execute protective operations according to the contingency plan (such as controlled micro-unloading of overloaded cable segments) until manual confirmation of safety or parameter adjustment is performed before tensioning can resume.

[0048] S8: Iterative judgment and phase advancement;

[0049] The system continuously repeats the complete closed-loop feedback control cycle consisting of real-time status monitoring and data processing, intelligent analysis and decision command generation, collaborative tensioning execution, and real-time safety monitoring, as described in S4 to S7. Within each tensioning stage, through multiple small-step incremental adjustments and real-time status feedback corrections, the system gradually drives the actual shape and internal force distribution of the structure to accurately approach and ultimately reach the control target set for that stage (within a preset accuracy range). Once the target of a tensioning stage is successfully achieved, the system automatically or manually confirms and enters the next tensioning stage. At this point, the reference target of the control algorithm switches to the shape and internal force values ​​of the next stage, and then the closed-loop iterative tensioning control process continues to repeat until the last tensioning stage is completed, and the entire structure reaches the final designed prestressed state and target geometric shape.

[0050] S9: Final acceptance;

[0051] After all predetermined tensioning stages have been completed and the structure has reached the final prestressed state required by the design and remained stable, a high-precision displacement monitoring system is used to comprehensively and meticulously verify the final geometric shape of the entire cable-membrane roof. The measured three-dimensional coordinates of each key point are compared with the design target coordinates to calculate the deviation and generate a deviation distribution map. Next, the final cable force values ​​of all major cable segments are reconfirmed. In addition to relying on online cable force sensor data, a certain proportion of cable segments are sampled using independent, calibrated portable cable force testing equipment. Subsequently, the membrane stress state is indirectly assessed by checking for obvious defects on the membrane surface and performing a final static analysis of the final state using an updated FEM model based on the final precise geometry and cable force data. Finally, all the verified final shape data, cable force data, and membrane state assessment results are rigorously compared with the target values ​​and allowable deviations specified in the design documents to evaluate whether the tensioning construction quality meets the design requirements and relevant standards and specifications.

[0052] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for synchronous tensioning and precision control of complex spatial cable trusses and membrane structures, characterized in that, The process includes the following: S1: Model Establishment and Target Determination; specifically including: establishing a coupled nonlinear finite element analysis model of the cable truss and membrane structure, and determining the structural morphology, cable force distribution, and membrane stress distribution under the final target tension state according to design requirements; at the same time, setting graded loading targets and control accuracy requirements for each stage of tensioning; S2: Deployment and initialization of the measurement and control system; specifically including: deploying a sensor network at key locations in the cable truss and membrane structure system to collect multi-point three-dimensional displacement, cable force of key cable segments and environmental parameters of the structure in real time and with high precision during the tensioning process; deploying multiple automated tensioning devices at key tensioning points of the structure; and calibrating all sensors and automated tensioning devices. Configure a central control processing unit, install data acquisition cards and control algorithm software to form a central control software system, establish a sensor network and data communication between the automated tensioning equipment and the central control software system, and set initial tensioning control parameters, tensioning sequence, tensioning targets at each stage and safety thresholds; the control algorithm software includes a model predictive control core module, a finite element model online calibration and update module, a multi-point collaborative and synchronous control logic module, and a safety monitoring and emergency handling logic module; S3: Start initial tensioning; specifically, the central control software system issues the first-stage tensioning command to each automated tensioning device based on the set initial tensioning parameters and sequence, or the initial loading path obtained from the preliminary open-loop prediction analysis of the finite element model. S4: Real-time status monitoring and data processing; specifically including: during the tensioning and adjustment process and each adjustment interval, the sensor network collects multi-point three-dimensional displacement, cable force, membrane surface status and environmental parameter data of the structure in real time, and transmits the collected multi-source heterogeneous data to the central control processing unit for preprocessing, time synchronization, coordinate transformation and data fusion to form a unified real-time status dataset of the structure. S5: Intelligent analysis and decision command generation; specifically including: the central control processing unit compares the real-time status dataset with the preset tensioning target for this stage and evaluates the deviation; based on the difference between the measured data and the finite element model prediction, it performs online calibration or status update of the key parameters of the finite element model; using the updated finite element model and optimized control algorithm, it comprehensively considers structural nonlinearity, cable-membrane coupling effect, current deviation and various safety and equipment constraints, and calculates the optimal coordinated tensioning increment command vector for all tensioning points that can make the structural state most effectively approach the next target state; S6: Coordinated tensioning execution; specifically including: the central control processing unit transmits the generated tensioning increment command vector to the local controller unit of each automated tensioning device, and each local controller unit drives the tensioning execution mechanism connected to it to perform corresponding loading, unloading, extension or retraction operations according to the received command and the specific increment value. S7: Real-time safety monitoring; specifically, it includes: throughout the entire tensioning process, the safety monitoring module inside the central control processing unit monitors the key safety indicators of the structure in real time, including the maximum cable force, the maximum displacement of nodes, and the maximum stress on the membrane surface. If any indicator approaches or exceeds the preset safety threshold, the tensioning will be automatically paused, an alarm will be triggered, and emergency adjustments or unloading operations will be performed according to the contingency plan. S8: Iterative judgment and stage advancement; specifically, it includes: repeating S4 to S7, iteratively adjusting through closed-loop feedback until the structural state reaches the control target and accuracy requirements of the current tensioning stage, and then entering the next tensioning stage; if it is the last stage, it continues until the final target tensioning state is reached; S9: Final acceptance; specifically includes: after all tensioning stages are completed, a final measurement of the overall structure's shape is checked and a comprehensive test of internal cable forces and membrane surface stress is conducted. After confirming that the design requirements are met, a construction process and result report is generated.

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