Finite element analysis + BIM technology for the overall hoisting construction of large-span spatial steel space frames

Abstract

This invention discloses a method for the overall hoisting construction of large-span spatial steel space frames using finite element analysis and BIM technology. This method first verifies the overall stress performance of the space frame through finite element analysis, determining the optimal hoisting points and wire rope parameters. Then, it uses BIM to assist in determining the ground assembly position of the space frame, selecting the appropriate crane type, determining the optimal crane hoisting position, and simulating the hoisting route to determine the optimal hoisting trajectory. By integrating a resistance strain monitoring system into the BIM software, the stress values ​​of each major load-bearing member of the space frame model during assembly and hoisting are directly displayed in the model. Corresponding stress thresholds are set according to specifications, allowing for intuitive monitoring of stress changes in each major load-bearing member. This ensures that any abnormalities are identified and their causes are determined immediately, enabling continuous monitoring throughout the entire space frame installation process and ensuring overall safety during hoisting.

Description

Technical Field

[0001] This invention relates to the field of large-span steel space frame hoisting technology, specifically to a method for the overall hoisting and construction of large-span spatial steel space frames using finite element analysis and BIM technology. Background Technology

[0002] With the rapid development of urbanization and the improvement of science and technology in my country, space frame structures with diverse shapes are increasingly being used in real life, especially large-span space frame structures. However, as the span of space frame structures continues to increase, the requirements for precision and accuracy in the construction process are also becoming higher. How to improve the efficiency of the entire construction process of space frame structures while ensuring safety is a crucial factor for the rapid development of space frame structures. Although steel space frame structures are highly statically indeterminate structures with good integrity and high safety, many complex technical issues in their design, manufacturing, and installation have not yet been fully understood. Slight negligence can easily lead to quality accidents or even complete collapse of steel space frame structures.

[0003] During actual transport, the operation involves multiple cranes or tower cranes working in coordination, placing extremely high demands on the operator's skills and experience. In the initial transport simulations, the steel space frame was vertically lifted and moved from multiple points (i.e., the wire ropes were vertical, and the steel space frame was always kept horizontal), thus determining the optimal lifting points, assembly positions, crane selection, and wire rope parameters. However, in actual operation, multiple cranes or tower cranes are operated simultaneously by different personnel, making it difficult to ensure that the wire ropes on different cranes or tower cranes are in the same vertical position. Therefore, the stress values ​​or horizontality of the steel space frame generated during the actual lifting process are completely different from the theoretical simulation, and the specific stress values ​​or horizontality of the steel space frame cannot be obtained in real time, resulting in a lack of scientific and objective real-time data and creating significant safety hazards.

[0004] This application is based on the specific problems encountered by the applicant, China Communications First Highway Engineering Co., Ltd., in the construction of the sports stadium space frame structure of the No. 8 resettlement area project of Zhengzhou Cultural and Creative Industry Park. The company has conducted a series of studies on the key technologies for the overall hoisting construction of large-span steel space frames by using finite element analysis combined with BIM technology, and has achieved fruitful results. Based on these results, the company has summarized the construction method for the overall hoisting construction of large-span spatial steel space frames using the integrated technology of finite element analysis and BIM.

[0005] The finite element analysis combined with BIM-based integrated technology for the overall hoisting of large-span spatial steel space frames is a comprehensive construction information management technology that integrates structural stress model establishment, construction model simulation, stress acquisition, analysis, and monitoring. Finite element software is used to analyze the stress performance of the space frame, determining the theoretical stress conditions of each member and the optimal hoisting point positions. The entire hoisting process is simulated using a BIM model to determine the optimal hoisting route. The BIM model is integrated into a resistance strain monitoring system for real-time monitoring of the hoisting process. This allows for more intuitive monitoring of stress changes and early warnings for each member during hoisting. After hoisting, this monitoring system can be used for full life-cycle monitoring of the space frame, ensuring its safety and stability throughout its entire lifespan. Summary of the Invention

[0006] The purpose of this invention is to provide a method for the overall hoisting and construction of large-span spatial steel space frames using finite element analysis and BIM technology, overcoming the shortcomings of existing technologies.

[0007] To achieve the above objectives, this invention provides the following technical solution: a finite element analysis + BIM technology method for the overall hoisting construction of a large-span spatial steel space frame. This method first verifies the overall stress performance of the space frame through finite element analysis, determining the optimal hoisting point position and wire rope parameters. On one hand, BIM assists in determining the ground assembly position of the space frame, selecting the crane type, determining the optimal crane hoisting position, and simulating the hoisting route to determine the optimal hoisting trajectory. On the other hand, for the stress values ​​of each load-bearing member of the space frame calculated by finite element software during assembly and hoisting, stress gauges are installed on the main load-bearing members. A resistance strain monitoring system is integrated into the BIM software, directly displaying the stress values ​​of each main load-bearing member in the model during assembly and hoisting. Corresponding stress thresholds are set according to specifications, allowing for intuitive monitoring of stress changes in each main load-bearing member. This ensures that any abnormalities are identified immediately, and continuous monitoring throughout the entire space frame installation process ensures overall safety during hoisting.

[0008] As a further aspect of the present invention: the optimal hoisting trajectory refers to the path formed by the two ends of the large-span spatial steel space frame in an S-curve manner.

[0009] As a further aspect of the present invention, the method for achieving the optimal hoisting trajectory is as follows: After determining the optimal hoisting point position, assembly position, crane selection, optimal crane hoisting position, and wire rope parameters; determine an error value with reference to the corresponding stress limit or the maximum allowable height difference between the two ends of the large-span spatial steel grid; take the intersection point of the extension line of the wire rope in the vertical state and the large-span spatial steel grid as the intersection point, and the wire ropes at both ends form two intersection points with the large-span spatial steel grid; the two intersection points are staggered as each other's centers, so that during the transfer process, crane one stops working, crane two rotates around crane one, and the stress value or height difference between the two ends of the large-span spatial steel grid generated by its rotation distance does not exceed the error value; after completion, crane two stops working, crane one rotates around crane two, and the stress value or height difference between the two ends of the large-span spatial steel grid generated by its rotation distance does not exceed the error value, and so on, alternatingly moving and transferring.

[0010] As a further aspect of the present invention: the method for obtaining the height difference between the two ends of the steel grid frame during the transfer process is as follows: a flexible tube is installed on the large-span spatial steel grid frame, and the flexible tube is filled with a colored liquid; wherein the two ends of the flexible tube are fixed on the large-span spatial steel grid frame and correspond to the extension lines of two steel wire ropes in sequence; the two ends of the flexible tube are at the same height, a transparent sleeve is fitted on the flexible tube, a round hole is provided at the top of the sleeve so that the flexible tube can communicate with the atmosphere, a soft cap is provided at the top of the sleeve to prevent the liquid from flowing out of the flexible tube when not in operation, and a displacement sensor is installed inside the sleeve.

[0011] As a further aspect of the present invention: A BIM+resistance strain monitoring system is set up using BIM technology to monitor relevant stress values ​​in real time during the hoisting process. The BIM+resistance strain monitoring system consists of a sensing layer, a transmission layer, and an application layer, specifically a sensor system, a data acquisition subsystem, a data transmission subsystem, a database subsystem, a data processing and control system, and a safety evaluation and early warning subsystem. Through the coordination of each layer, the various functions of the system are realized.

[0012] The design principles of this invention, its technical differences from existing technologies, and its effects:

[0013] 1. Precision: Through finite element analysis, the stress state of each member of the space frame during the hoisting process and after installation is accurately calculated to determine the optimal hoisting point position and assembly scheme of the space frame.

[0014] 2. High efficiency: By using BIM technology to simulate crane selection, parking space location, and hoisting route planning, the selection of cranes can be completed in the shortest possible time with the assistance of information technology. The three-dimensional characteristics of the software are used to determine the crane location and simulate the entire hoisting trajectory, thereby determining the optimal hoisting route. BIM model animations are used to provide intuitive explanations to managers and operators, greatly improving work efficiency.

[0015] 3. Safety: The ground assembly and hoisting process adopted in this construction method greatly reduces the risk of workers working at heights. By integrating a resistance strain monitoring system to monitor the stress of each member during the assembly and hoisting process of the space frame itself, it ensures that the stress and strain of each member are within the allowable range, thus ensuring the safety of space frame construction in all aspects.

[0016] 4. Economy: This construction method uses ground assembly technology to install the space frame, which greatly improves the installation efficiency of workers, reduces the frequency of crane use, and eliminates the need for the installation of the support system, thus saving a significant amount of labor and machinery costs.

[0017] 5. Fast: Before construction, BIM + finite element analysis is used to plan the entire construction deployment of the space frame, optimizing and simplifying the entire construction process. By changing the traditional high-altitude assembly to ground assembly, the installation time is reduced, effectively shortening the construction period.

[0018] 6. An error value is creatively set in the early theoretical simulation stage. This error value is determined by the corresponding stress limit or the maximum allowable height difference between the two ends of the large-span spatial steel space frame. The stress value can include the stress values ​​at the connection points of various parts of the steel space frame and the stress values ​​between the wire rope and the steel space frame. The height difference between the two ends of the large-span spatial steel space frame is measured by flexible hoses at both ends at the same height. This ensures that if the real-time monitoring data does not exceed the error value during actual transport and overcharging, the risk is within the acceptable range; if it exceeds the error value, work is immediately stopped for safety protection, greatly improving safety.

[0019] 7. This invention is applicable to medium and large span steel space frame structures such as stadiums, exhibition halls, and warehouses. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a flowchart of the construction process of the present invention;

[0022] Figure 2 This is a schematic diagram of the overall modeling of the space frame obtained through finite element analysis in this invention. Figure 1 ;

[0023] Figure 3 This is a schematic diagram of the overall modeling of the space frame obtained through finite element analysis in this invention. Figure 2 ;

[0024] Figure 4 This is a schematic diagram of the lifting point selection in this invention;

[0025] Figure 5 This is a diagram showing the planar movement trajectory of the steel space frame in this invention;

[0026] Figure 6 This is a schematic diagram of the software structure in this invention.

[0027] The numbers in the diagram are: 1. Crane; 2. Indoor sports field; 3. Schematic diagram of the running trajectory of the steel grid; 4. Steel grid assembly site; 5. Hoses; 6. Colored liquid; 7. Transparent sleeve; 8. Displacement sensor; 9. Circular hole. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0029] refer to Figure 1-6 This embodiment provides a method for the overall hoisting construction of large-span spatial steel space frame using finite element analysis and BIM technology. This method is applied to the construction of the space frame structure of the gymnasium in the No. 8 resettlement area project of Zhengzhou Cultural and Creative Industry Park.

[0030] I. Finite element analysis + BIM crane selection and routing

[0031] 1 Overall Modeling

[0032] Based on the characteristics of the project, before modeling, we fully understood the material strength values ​​and stress calculations of each member in the design calculation book of the design institute, and checked the position of each support and the overall stress situation after the installation of the space frame in the drawings.

[0033] (1) Material weight statistics. Based on the material characteristics, the weight of each material of the space frame is comprehensively and systematically counted to avoid omissions. The weight is confirmed after being checked against the design statistics. If there are any abnormalities, the design should be communicated and confirmed in time.

[0034] (2) Mechanical properties of material design.

[0035]

[0036]

[0037]

[0038] 4) Overall modeling and weight verification of the space frame

[0039] After constructing each member of the space frame using finite element method software, the stress conditions of each support are extracted and compared with the calculations in the design drawings. Once confirmed to be correct, the next construction step is taken. Figure 2 and 3 .

[0040] 2. Selection of hanging points

[0041] Taking the steel space frame structure roof of the gymnasium in Project No. 8 of the Cultural and Creative Park as an example, since the longitudinal span of the space frame is 82m, selecting the suspension points at the short side supports would result in excessive axial pressure on the thin bars at the top of the mid-span, causing the stability of the compression members to fail to meet the specifications. Therefore, the suspension points should be closer to the mid-span, with a straight-line distance of 8.2m from the edge projection. After trial calculations, the suspension points are as follows: Figure 4 As shown.

[0042] 3. Selection of Wire Rope and Machine Model

[0043] Each wire rope and its selection

[0044] 1) Length of each wire rope

[0045]

[0046] Note: The angle between the wire rope and the horizontal plane of the space frame is 60 degrees.

[0047] 2m is the length of the steel wire rope binding ball node.

[0048] 2) Wire rope tension

[0049] According to Clause 6.1.8 of the Technical Specification for Space Frame Structures JGJ7-2010, the dynamic coefficient for installing segmental structures should be selected according to the following values: 1.4 for crawler cranes and truck cranes.

[0050]

[0051] 3) Steel Wire Rope Selection

[0052] If the wire rope is used for motorized lifting with a safety factor of 6, then the total tensile force is 91.5 * 6 = 549 kN.

[0053] According to Table 9 of "Important Purpose Steel Wire Ropes", select a fiber-core steel wire rope with a single strand diameter of 34mm and a nominal tensile strength of 1570MPa. The unit weight of the steel wire rope is 4.06Kg / m. Therefore:

[0054]

[0055]

[0056] Crane selection

[0057] 1) Calculation of lifting load

[0058] The steel grid structure of the gymnasium in Project No. 8 of the Cultural and Creative Park has a span of 70m×40m. It is planned to use two truck cranes to lift the structure into place at one time for the hoisting construction. According to Article 3 of 7.5.5 of the "Safety Technical Specification for Lifting and Hoisting Engineering in Building Construction", the lifting load of each of the two truck cranes shall be calculated with a coefficient of 0.8.

[0059]

[0060] 2) BIM integration into crane selection and hoisting

[0061] Based on the lifting parameters of each truck crane, the optimal truck crane model and the best lifting position are determined in the shortest possible time by using BIM software models for trial matching.

[0062] The steel space frame hoisting of the gymnasium in Project No. 8 of the Cultural and Creative Park will be carried out using a Zoomlion QAY180 (55-ton counterweight) truck crane, with the center of the outriggers 1m from the wall and the space frame no less than 2m from the wall during hoisting.

[0063] 3) Bearing capacity of the foundation at the outrigger

[0064] The Zoomlion QAY180 truck crane has a curb weight of 71t, a counterweight of 55 tons, and a total weight of 126t. The outriggers have a longitudinal and transverse span of 8.8m and a maximum load capacity of 66.7t.

[0065] The bearing capacity of the foundation at the crane outriggers must be no less than 200 kPa.

[0066]

[0067] 4) Design of reinforced concrete pads for outriggers

[0068] A cast-in-place concrete slab with dimensions of 1.5m x 1.5m x 0.55m is constructed, with a 10mm diameter steel mesh at the bottom, spaced 150mm apart, and a 30mm protective layer. The soil resilient modulus is 20MPa, and the load at the concrete foundation support is 66.7t. Calculations show that the first maximum principal stress of the concrete is 1.233MPa < 1.43MPa; the first maximum principal stress of the steel mesh is 2.103MPa, which meets the requirements.

[0069] 4. BIM integration for determining the hoisting route of the space frame

[0070] The steel space frame of the gymnasium in Project No. 8 of the Cultural and Creative Park was hoisted using a dual-crane lifting system. To ensure that the steel wire rope of the truck crane remained in a near-vertical state and that the stress values ​​did not exceed the error values ​​during the hoisting process, the stress value error values ​​at each position and the maximum deviation of the high end of the steel space frame were determined in the preliminary simulation. During the actual transfer process, if any vertical deviation at the corresponding position or height difference exceeded the error value, work was stopped for safety protection.

[0071] The real-time stress at each location is tracked in real time using BIM technology and a monitoring system, with stress sensors installed at corresponding locations. The height difference of the steel space frame is determined by flexible tubes installed on the large-span spatial steel space frame, filled with a colored liquid. The two ends of the tubes are fixed to the large-span spatial steel space frame and correspond to the extension lines of two steel wire ropes. The two ends of the tubes are at the same height, and a transparent sleeve is fitted over the tubes. A round hole is set at the top of the sleeve to allow the tubes to communicate with the atmosphere. A soft cap is set at the top of the sleeve to prevent the liquid from flowing out of the tubes when not in operation. A displacement sensor is installed inside the sleeve. The judgment is made by the displacement sensor signal and whether the colored liquid exceeds the warning line in the sleeve.

[0072] The specific operation process involves crane one stopping during transport, while crane two rotates around crane one. The stress value generated by the rotation distance or the height difference between the two ends of the large-span steel space frame does not exceed the error value. After completion, crane two stops, and crane one rotates around crane two. The stress value generated by the rotation distance or the height difference between the two ends of the large-span steel space frame does not exceed the error value. This staggered transport is repeated (this scheme completely solves the coordination problem between multiple tower cranes, achieving one operation while the other stops, staggered work, and avoiding safety hazards caused by coordination errors). During horizontal lifting, the steel space frame travels in an S-shaped path. The specific travel path and distance of the coordinated translation of the two cranes are simulated and debugged using a BIM model to ensure the safety and coordination of the translation of the two cranes. Figure 5 and 6 As shown:

[0073] 2BIM + Resistance Strain Monitoring System

[0074] 1 System Design Principles

[0075] This system was developed by a professional software development service company based on traditional resistance strain monitoring systems, forming a comprehensive monitoring system integrated with BIM model software. This system allows for 24 / 7 uninterrupted comprehensive monitoring via computer and mobile client, ensuring direct monitoring of all major load-bearing members of the steel space frame throughout the entire installation process.

[0076] The system design should adhere to certain principles, striving for reliability, economy, and rationality. The monitoring system provides tools for acquiring structural information, enabling decision-makers to make correct decisions regarding specific objectives. The design principles are as follows:

[0077] 1) Ensure the effectiveness of the system. Based on the structural characteristics of the steel space frame, determine the monitoring items and sensor measurement point layout of the monitoring system according to the requirements of structural condition identification and safety assessment.

[0078] 2) Ensure system reliability: Since the steel space frame structure safety monitoring system operates outdoors in real time, the system reliability must be guaranteed. Otherwise, even advanced instruments will not be able to play their due role and effect if the system is damaged.

[0079] 3) Ensure the system's advanced nature: The selection of equipment and the functions of the monitoring system are compatible with the current level of mature monitoring and testing technologies and the development of relevant theories of structural safety monitoring, and have advanced and forward-looking early warning capabilities.

[0080] 4) Operability and maintainability: The system should be easy to manage and operate, and the technical level and ability requirements for operation and maintenance personnel should not be too high, and it should be easy to upgrade and replace.

[0081] 5) The system should have good openness and compatibility. While meeting functional requirements, it should fully consider the rapid development of modern technology to facilitate system upgrades. It should also be able to interface with traffic engineering, management, and maintenance systems to achieve information sharing.

[0082] 6) The system has a remote firmware upgrade function: Based on the system self-test and system requirements, the firmware can be improved remotely, and the system has various types of communication protocols and interfaces, which can provide services for future equipment upgrades.

[0083] 7) Optimal cost control: One principle of the monitoring system is to use the optimal deployment method to save project costs and manpower and material resources for later maintenance, while maximizing the actual monitoring and monitoring effect.

[0084] In summary, the system adheres to the basic principles of "technological feasibility, implementation possibility, and economic rationality," ensuring that the monitoring system is usable, practical, and easy to use, and fully leveraging its role to provide data and technical support for management and safety during the construction of steel space frame structures.

[0085] 2 System Composition

[0086] The system consists of a perception layer, a transmission layer, and an application layer. Specifically, it comprises a sensor system, a data acquisition subsystem, a data transmission subsystem, a database subsystem, a data processing and control system, and a safety evaluation and early warning subsystem. These layers coordinate with each other to achieve the system's various functions. The system's composition and functions will be described below.

[0087] 1) Sensor Subsystem

[0088] The automated monitoring sensor subsystem, as the perception layer, is the foundation of the entire monitoring system. It provides accurate, real-time, and reliable safety monitoring data for various aspects of the monitored structure even under harsh conditions. The sensor subsystem converts changes in the structure's physical quantities into other signals, such as sound, light, electricity, and magnetism, quantifying these changes and converting them into familiar numerical values ​​to understand the structure's stress and other parameters.

[0089] 2) Data Acquisition Subsystem

[0090] The data acquisition subsystem collects environmental conditions and structural signals (such as acoustic, optical, electrical, and magnetic signals) measured by the sensor subsystem, and processes these signals into digital signals. The data acquisition subsystem should have diagnostic capabilities, quickly identifying abnormal data, sensor failures, and damaged areas. It should also ensure normal operation under harsh weather conditions (such as rain, snow, hurricanes, earthquakes, and heavy rain), continuously collecting and transmitting information data from various structural safety monitoring items. The data acquisition subsystem also has some preliminary data processing capabilities.

[0091] 3) Data transmission subsystem

[0092] Common communication methods used in data transmission subsystems include GPRS / 3G / 4G, fiber optic, and wireless bridges. The principles for selecting the networking method are as follows:

[0093] ① In areas where mobile signal coverage is available, GPRS / 3G / 4G should be given priority for network construction, and operators should choose according to the actual situation;

[0094] ② When there is no mobile phone signal or the data traffic is too high on site, fiber optic transmission must be used.

[0095] 4) Database Subsystem

[0096] A database subsystem is a data processing system, a software system that provides data to a practically operational storage, maintenance, and application system. It is a collection of storage media, processing objects, and management systems. Its software mainly includes the operating system, various host languages, utilities, and the database management system. The database subsystem is uniformly managed by the database management system; data insertion, modification, and retrieval are all performed through the database management system. The data administrator is responsible for creating, monitoring, and maintaining the entire database, ensuring that the data can be effectively used by anyone with the appropriate authority.

[0097] 5) Data Processing and Control Subsystem

[0098] The data processing and control subsystem is the next link in the data transmission subsystem. The large amount of raw data collected and transmitted by the data acquisition and transmission subsystem requires further processing and analysis through this subsystem. This includes data verification and validation, preliminary overall data analysis, and responding to instructions from subsequent subsystem functional modules through software and hardware systems. The data processing and control subsystem implements structured processing such as data querying, storage, and visualization. It controls the data acquisition equipment installed in the structured data structure and extracts and processes data through database operations. It is a key system component for processing and analyzing raw data.

[0099] Data processing and control mainly includes filtering and secondary processing of data, and displaying it using raw data or curves. Then, the raw data or curves can be displayed on the APP or PC, and relevant tables and data can be printed.

[0100] 6) Safety assessment and early warning subsystem

[0101] The main function of the safety assessment and early warning subsystem is to statistically analyze the collected data and determine the range of deformation and stress values ​​for key structural components and control sections under various environmental conditions, specific temperatures, and loads. It monitors changes in key parameters under various circumstances and identifies trends based on the data. In the event of emergencies, it can anticipate various structural conditions and issue early warnings when deformation and stress reach limits. Combined with the early warning mechanism, it promptly implements appropriate mitigation measures for unstable or potentially unstable structures to prevent disasters from occurring or escalating and to minimize losses.

[0102] 3 Distributed Wireless Data Acquisition System

[0103] In the safety monitoring industry of engineering construction, higher demands are placed on the diversity of monitoring objects, the stability of measurement systems, and the ease of installation. Traditional monitoring methods mainly involve integrating single-function modules, such as inclinometers and vibrating wire acquisition devices, and transmitting data via industrial bus networks. This approach suffers from drawbacks such as system complexity, large wiring workload, and high maintenance costs, making it difficult to meet the requirements of the safety monitoring industry. Therefore, a distributed cloud-based intelligent data acquisition system with wireless transmission and multi-parameter measurement can be used for monitoring and safety stability analysis of projects such as building foundation pits, dams, bridges, subways, and transportation and municipal engineering.

[0104] The distributed cloud intelligent data acquisition system is a multifunctional wireless data acquisition system that utilizes multiple communication interfaces and Zigbee communication technology. It can perform various interface protocol conversions and automatically manage wireless data transmission. It solves the problems of traditional methods, such as reliance on module integration, low reliability of hardware wiring, and high maintenance costs, and offers advantages such as automatic data acquisition, wireless distributed installation, easy maintenance, and high reliability.

[0105] 4-node and its working principle

[0106] The Zigbee-based wireless node integrates a vibrating wire sensor and RS485 sensor measurement circuitry, and is extended to multiple outputs via a switch. A built-in lithium battery powers the entire module, while an external solar panel provides extended battery life.

[0107] The data acquisition node can be configured with a data acquisition cycle according to requirements. Each acquisition cycle involves the node waking up and acquiring data once, then going into sleep mode after acquisition, waiting for the next acquisition cycle to wake up again. This operating mode significantly reduces the node's power consumption, enabling low-power operation and ensuring normal operation even when powered solely by solar energy.

[0108] The data acquisition node has a built-in 2MB memory for backing up the acquired data (circular storage). When a network failure causes the node to be unable to report data in a timely manner, the wireless gateway can recover the data from the node (repeater) by recording the data interruption time of a certain node.

[0109] The data acquisition nodes have a low battery warning function. When the battery level falls below a set warning threshold, they will send a low battery warning to the gateway in advance. While operating, the nodes can upload their current signal strength value to the gateway. This value can be viewed in the diagnostic function of the Anxin Cloud platform. The signal strength displayed by a relayed data acquisition node represents the signal strength from that data acquisition node to the relay node.

[0110] 5. Gateways and their working principles

[0111] The gateway is a multi-functional acquisition module with a built-in embedded processor. Because it supports many peripherals, it needs mains power to ensure long-term stable operation. In addition, the wireless gateway has a built-in reserve battery to report fault information and power failure information to Anxin Cloud after a power outage on site.

[0112] The gateway has a built-in Zigbee coordinator for managing all Zigbee nodes within its jurisdiction (under the same Zigbee subnet number). It also has a built-in DTU module that sends data collected by the Zigbee coordinator to a distributed cloud-based intelligent rigging load monitoring platform.

[0113] The gateway has a built-in SD card for storing gateway communication logs and firmware upgrades. Users can also view the gateway's communication status in real time through the communication interface. Additionally, an external battery can be configured on-site based on the gateway's power consumption to ensure real-time data upload across the entire network. The gateway features a low battery warning function; it will issue an early warning when the battery level falls below a set threshold.

[0114] 7 software platforms

[0115] 1) Platform System

[0116] The system adopts a layered B / S architecture, using .NET as the development platform and HTML5, CSS3, RAI, and ADO.NET as its core technologies. It employs the popular Metro UI interface style, unifying process specifications, technical standards, data management, role management, user login, and interface style to form an open and unified platform for building a layered online security monitoring system. Due to the relatively complex business logic of this project, to ensure a clear logical structure for the entire system, reduce development difficulty, and allow programmers to focus more on designing the system's business processes, further measures are taken.

[0117] 2) Software platform functions

[0118] The system provides a user-friendly interface for easy operation, including the management and analysis of various monitoring parameters and data, and has the following functions:

[0119] ① Comprehensive management of test data for various parameters: This solves the problem of managers having to deal with multiple data acquisition systems, as they only need to retrieve information from a unified database.

[0120] ② Sensor information description and recording: Information such as the sensor's installation location, equipment location and number can be entered, and information related to the project can be recorded to facilitate sensor management.

[0121] ③ Capable of remote control of hardware systems: The integrated management system, combined with intelligent instruments, can remotely adjust test parameters, avoiding the problem that traditional instruments and systems must enter the foundation pit site to change parameters.

[0122] ④ It can preprocess test data: Its main functions include data filtering, data compression, and data classification, providing a good information source for subsequent automatic and manual analysis.

[0123] ⑤ Display of data at each stage: It can display real-time monitoring data, retrieve historical data for display, or display and analyze several parameters simultaneously.

[0124] ⑥ Data analysis function: mainly performs various analysis and processing on the data, including statistical analysis, structural parameter identification, and structural safety assessment.

[0125] ⑦ Automatic Reporting Function: Based on the results of automatic or manual analysis by the system, various types of reports can be automatically generated.

[0126] ⑧ Security assurance for system management: To ensure the safe operation of the online safety monitoring system for foundation pits, different permissions are provided to different administrators, user identities are verified, and the provided functions include viewing, searching, modifying, adding, and deleting.

[0127] Three Quality Controls

[0128] 1. Space frame assembly

[0129] (1) The bolts should be tightened properly, and there should be no gaps visible to the naked eye on the contact surface of the sleeve.

[0130] (2) The members are not allowed to have bending exceeding the specified limit.

[0131] (3) The surfaces of the installed space frame components must be clean, intact, undamaged, dent-free, and correctly installed. If any incorrect installation is found, the components must be replaced immediately.

[0132] (4) The offset of the center of the grid node is no more than 1.5, and the length error of the single cone grid is no more than +1.5.

[0133] (5) After the overall grid is installed, the longitudinal and transverse lengths shall not exceed L / 2000 and shall not exceed 30, and the center offset of the support shall not exceed L / 3000 and shall not exceed 30.

[0134] (6) The height difference between adjacent supports shall not exceed 15, and the height difference between the highest and lowest supports shall not exceed 30.

[0135] (7) The no-load deflection is controlled within L / 800.

[0136] (8) Quality inspectors shall have sufficient total station, theodolite, level, steel tape measure and auxiliary measuring tools and instruments such as line, cone and steel ruler.

[0137] (9) Inspectors shall remain on-site without interruption or leaving their posts. They shall continuously monitor, record, complete documentation, and report to the quality engineer, project manager, and supervising engineer in a timely manner, and cooperate closely with them.

[0138] 2. Lifting Simulation

[0139] Based on the construction drawings, we invited company experts to simulate the construction process of the hoisting scheme, calculate and determine the model of the truck crane, the selection of the crane and hoisting point positions, and the overall stress change trend of the grid structure during the hoisting process (see calculations and attached diagrams for details), to ensure that the hoisting construction minimizes economic costs while guaranteeing safety and quality.

[0140] 3 lifting

[0141] (1) The company’s experts and Zhengzhou University experts were invited to verify the entire hoisting plan to ensure the comprehensiveness and accuracy of the verification.

[0142] (2) Before hoisting, stress plates are installed on the main load-bearing members to monitor the stress of the space frame and ensure the overall quality stability of the space frame.

[0143] (3) Install lifting weight and anti-tilt devices on the truck crane to ensure the safety of the truck crane lifting process.

[0144] Four safety measures

[0145] 1. Principles for determining early warning thresholds

[0146] Determining and setting warning values ​​is a very rigorous and serious process. Warning values ​​differ for different test locations on different structures, therefore, targeted analysis is required to determine the appropriate warning value. For foundation pit structures, there are several ways to determine warning values:

[0147] (1) Provided by the design institute. The design institute has established a finite element model to calculate the deformation and stress state of the structure when designing the drawings, and provides reasonable control values ​​for each monitoring item of the structure. Therefore, the control values ​​provided by the design institute are the first reference for determining the early warning value.

[0148] (2) Theoretical calculation: The structural response caused by the design load is used as one of the standards for early warning values. At this time, an accurate finite element model and load estimation are required.

[0149] (3) Information obtained from construction monitoring. This reflects the initial health information of the structure and is of great significance.

[0150] (4) Actual testing, combined with relevant specifications and existing manual testing data and reports, yields the initial warning value. After the equipment is installed and the system is in operation, monitoring data from the following three months or six months is accumulated to establish a basic warning database. This data is then analyzed, and the initial warning value is adjusted to better reflect the actual condition of the structure.

[0151] 2. Tiered early warning

[0152] The determination of the early warning level is based on on-site monitoring data, verification, comprehensive analysis, and expert consultation to determine the magnitude of the project risk, determine the corresponding early warning level, and provide real-time warnings for relevant monitoring content.

[0153] The warning levels are divided into four levels according to the engineering risk, from lowest to highest: blue warning, yellow warning, orange warning and red warning, as shown in the table below.

[0154]

[0155] Level 1 Warning (*90%): The monitoring data for the day meets the monitoring and warning requirements, and there are no effective measures. The overall assessment is that the risk is unacceptable, and the project is in an emergency response state.

[0156] Level 2 Warning (*80%): The monitoring data for the day meets the monitoring and warning requirements, and the surrounding environment is complex. Based on the comprehensive judgment, it is determined that the project is in an unsafe state and the project is unwilling to accept the risk. Immediate measures must be taken on site.

[0157] Level 3 Warning (*70%): The monitoring data for the day meets the monitoring and warning requirements, and the overall assessment is that the risk is acceptable. Preventive measures must be taken on site.

[0158] Level 4 Warning (*60%): The monitoring data for the day meets the monitoring and warning requirements, and the overall assessment is that the risk is acceptable. No preventive measures are required on-site, but vigilance should be increased.

[0159] In addition to computer alerts, there is also an SMS alert function, which allows users to add the mobile phone number of the user being notified.

[0160] Different early warning mechanisms are determined based on different warnings. The safety system performs real-time automatic monitoring of the foundation pit. Based on historical monitoring data, the monitoring data is preprocessed and analyzed in real time using statistical methods, time sequence methods, and other means. If there is a significant abnormal change in the safety warning indicators, an early warning signal (SMS) is immediately issued to prevent accidents from occurring. If the change in the safety warning indicators is not very obvious, the comprehensive assessment system is immediately triggered to conduct analysis and assessment, and then corresponding measures are taken based on the assessment results.

[0161] 3. Safety Measures

[0162] (1) Establish a safety production responsibility system: conscientiously implement the principle of safety first and prevention foremost. The project manager is the first person responsible for the safety production of the project, and the safety officer is the person directly responsible for safety. Establish and improve the safety production responsibility system at all levels and in all departments, formulate reward and punishment measures, and ensure that responsibilities are assigned to specific individuals. Adhere to regular safety inspections and promptly identify potential safety hazards.

[0163] (2) A safety duty system shall be implemented during the construction of the steel space frame. The leadership safety duty inspection system shall be strengthened. Each construction procedure must have detailed technical and safety instructions and complete signatures before construction can begin.

[0164] (3) Each work team shall have a dedicated safety officer to assist the project safety officer in their work, strictly implement all production management systems and operating procedures, and ensure that a safety officer is present whenever construction is underway. Safety hazards shall be identified and corrected promptly. Safety education for all employees shall be strengthened to ensure that all employees firmly establish the awareness of "safety first, prevention foremost," overcome complacency, and organize targeted learning of safety production knowledge and regulations, ensuring that they attach importance to safety in their thinking and strictly implement safety measures in production. New workers must receive safety education and sign safety agreements upon entering the site. Seasonal safety education shall be provided to external personnel during seasonal changes. Safety education shall be conducted at least once a week, and violations of command and operation regulations shall be resolutely stopped. The safety production responsibility system shall be implemented and all regulations shall be enforced.

[0165] (4) All participants must undergo safety training before entering the site and pass the examination before commencing work. Frontline workers should master the operating skills of their respective jobs and be familiar with the safety operating procedures for their jobs. Operators of various types of machinery and equipment, electricians, welders, and other similar jobs must undergo specialized safety operation training and pass the examination before they can be certified to work.

[0166] (5) Safety signs shall be placed at key and hazardous locations on the construction site, such as the edge of the foundation pit, to remind employees to pay attention to safety. No one is allowed to dismantle any safety equipment or facilities on site without authorization.

[0167] (6) Special operation personnel must hold a certificate to work and wear appropriate labor protection equipment.

[0168] (7) All personnel entering the construction site must wear safety helmets correctly, abide by rules and regulations, and wear identification badges.

[0169] (8) Adhere to the pre-shift speech for the work team.

[0170] (9) In accordance with the construction plan, there must be safety production publicity signs at the construction site, and safety publicity slogans or safety warning signs must be hung on the main working surfaces and passageways.

[0171] (10) Regularly maintain the construction access road, especially strengthen maintenance and repair in rainy weather, and prevent traffic accidents.

[0172] (11) Strengthen the inspection, maintenance and repair of equipment to ensure that safety devices are complete, sensitive and reliable, and ensure the normal and safe operation of equipment.

[0173] (12) Construction electricity use must comply with electrical safety regulations. On-site electrical equipment must have leak prevention measures, and non-electricians are not allowed to install or operate electrical equipment.

[0174] (13) There must be sufficient lighting equipment for nighttime lighting. Handheld lights must use 36V low voltage electricity. Electrical equipment must have a reliable grounding wire. Operators of electrical equipment must wear protective equipment and insulating gloves when operating.

[0175] (14) During the construction of the foundation pit, protective railings and access walkways for personnel and horses should be installed. Loose bricks, tiles and stones near the pit walls and top should be removed to prevent them from falling and injuring people. Special personnel should be assigned to patrol the perimeter of the foundation pit to ensure the safety of construction workers at the bottom of the pit and those walking along the edge of the pit.

[0176] (15) After strong winds and rain, all safety facilities must be carefully inspected and hidden dangers must be eliminated before construction can continue.

[0177] Five Resources Conservation

[0178] 1. Reduced costs of machinery, materials, and labor.

[0179] (1) Compared with traditional steel grid construction, this method reduces the frequency of use of truck cranes. It does not need to be used in the assembly stage, but only once in the final overall hoisting stage.

[0180] (2) Compared with traditional steel space frame construction, the traditional steel space frame installation method requires a lot of scaffolding to assist in the steel space frame assembly operation. This method only requires underground assembly and one-time hoisting, without the need for additional scaffolding materials.

[0181] (3) Compared with traditional steel grid construction, this method only requires the installation workers to assemble the structure underground, eliminating the need for high-altitude assembly work, which greatly improves the workers' labor efficiency and saves labor costs.

[0182] Phase 2 shortening

[0183] Compared with traditional steel space frame construction, this method changes high-altitude assembly to underground assembly, reducing the use of machinery and materials, and improving the labor efficiency of workers, thereby reducing the construction period to more than half of the traditional construction period.

[0184] Six-Benefit Analysis

[0185] 1. Economic benefits:

[0186] The finite element analysis (FEM) + BIM technology method for the overall hoisting construction of steel space frames utilizes FEM calculations to accurately calculate the stress state of each member during and after hoisting, determining the optimal hoisting point locations and assembly scheme. BIM model animations provide intuitive explanations to management personnel and workers, significantly improving work efficiency. The entire construction process is optimized and streamlined, and by shifting from traditional high-altitude assembly to ground-based assembly, installation time is reduced, effectively shortening the construction period.

[0187] Compared with high-altitude assembly, it greatly improves the installation efficiency of workers, reduces the frequency of crane use, and eliminates the need for support system installation, resulting in significant savings in labor and machinery costs.

[0188]

[0189] 2. Quality and Efficiency:

[0190] The application of finite element analysis (FEM) + BIM technology in the overall hoisting of steel space frames throughout the construction process shows a trend towards multi-stage, integrated, multi-faceted, and collaborative applications, with its application depth continuously deepening. This can effectively improve the technical and management level of quality control during construction. Therefore, applying BIM technology to construction quality control has significant exploratory value. By summarizing and analyzing the current status of construction quality control, this paper proposes an implementation framework for quality control of the overall hoisting technology of steel space frames using FEM + BIM. The specific implementation of this framework is discussed from three perspectives: from the perspective of model quality control, standardized management and implementation details for BIM-based model quality control are formulated; from the perspective of the three stages of construction quality control (pre-construction, during-construction, and post-construction), a three-stage implementation strategy for construction quality control based on BIM is proposed; and from the perspective of all parties involved in construction quality control, including the BIM-led party, designer, contractor, supervisor, and owner, a collaborative implementation strategy for BIM is proposed. Based on the analysis from the above three perspectives, fully leveraging the advantages of BIM models in data sharing and transmission throughout the process, and integrating all information from the construction site onto a unified management platform using different software platforms combined with advanced technologies such as the Internet of Things and mobile applications, we can achieve standardized and systematic management of construction process quality control. This study aims to comprehensively and deeply explore and demonstrate the implementation and application of finite element analysis + BIM technology in the overall hoisting of steel space frames to improve construction process quality control.

[0191] 3. Social benefits:

[0192] Through the application of finite element analysis + BIM technology in the overall hoisting of the steel space frame in this project, the construction of the steel space frame roof remained safe and controllable throughout the project's construction period, from commencement to completion. This technology has already been promoted and applied internally within the company. The company's Zhongmu County Youth Activity Center project also used this technology for the construction of its steel space frame roof, achieving good results. The BIM technology industry highly recognizes this technology, its application prospects are promising, and it is worthy of promotion.

[0193] Finite element analysis combined with BIM technology allows for automated installation of the entire steel space frame, requiring little to no human intervention. This reduces manpower and material costs, resulting in economic savings. Monitoring equipment has a long effective lifespan and a high recycling rate.

[0194] The finite element analysis (FEM) + BIM technology method for the overall hoisting construction of steel space frames has been applied in Project No. 8 of the Zhengzhou International Cultural and Creative Industrial Park in Zhongmu County and the Zhongmu County Youth Activity Center project. Through finite element analysis, the stress state of each member of the space frame during and after hoisting is accurately calculated, determining the optimal hoisting point positions and assembly scheme. BIM model animations provide intuitive instructions to management personnel and workers, significantly improving work efficiency. The entire construction process has been optimized and streamlined, and by changing traditional high-altitude assembly to ground assembly, installation time has been reduced, effectively shortening the construction period. Compared to high-altitude assembly, this method significantly improves worker installation efficiency, reduces crane usage frequency, and eliminates the need for support system installation, resulting in substantial savings in labor and machinery costs.

[0195] This construction method can be used for public buildings, such as warehouses and stadiums. It has obvious effects, requires simple materials and equipment, is easy to operate, and has good social and economic benefits.

[0196] Finally, it should be noted that when describing the position of each component and the mating relationship between them, the present invention usually uses one or a pair of components as examples. However, those skilled in the art should understand that such positions, mating relationships, etc., are also applicable to other components or other pairs of components.

[0197] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A method for the overall hoisting and construction of a large-span spatial steel space frame using finite element analysis and BIM technology, characterized in that: This method first verifies the overall stress performance of the space frame through finite element analysis, determines the optimal position of the hoisting points and the wire rope parameters, and then uses BIM to assist in determining the ground assembly position of the space frame, selecting the crane type, determining the optimal crane hoisting position, and simulating the hoisting route to determine the optimal hoisting trajectory. On the other hand, it calculates the stress values ​​of each load-bearing member of the space frame during assembly and hoisting using finite element software, installs stress gauges on the main load-bearing members, and integrates a resistance strain monitoring system into the BIM software. This directly displays the stress values ​​of each main load-bearing member in the model during assembly and hoisting, and sets corresponding stress thresholds according to specifications. This allows for intuitive monitoring of stress changes in each main load-bearing member, ensuring that any abnormalities are identified and their causes are determined immediately. Continuous monitoring throughout the entire space frame installation process ensures overall safety during hoisting. The optimal hoisting trajectory refers to the path formed by the two ends of a large-span spatial steel space frame traveling in an alternating manner, creating an S-curve. The method to achieve the optimal hoisting trajectory is as follows: after determining the optimal hoisting point position, assembly position, crane selection, optimal crane hoisting position, and wire rope parameters, determine an error value with reference to the corresponding stress limit value or the maximum allowable height difference between the two ends of a large-span spatial steel grid. The intersection point of the vertical extension line of the steel wire rope and the large-span spatial steel grid is taken as the intersection point. The steel wire ropes at both ends form two intersection points with the large-span spatial steel grid. The two intersection points are staggered and serve as the centers of each other. During the transfer process, crane one stops working, and crane two rotates around crane one. The stress value generated by the distance of its rotation or the height difference between the two ends of the large-span spatial steel grid does not exceed the error value. After completion, crane two stops working, and crane one rotates around crane two. The stress value generated by the distance of its rotation or the height difference between the two ends of the large-span spatial steel grid does not exceed the error value. The transfer is carried out in an alternating manner.

2. The method for overall hoisting and construction of large-span spatial steel space frame using finite element analysis + BIM technology as described in claim 1, characterized in that... The method for obtaining the height difference between the two ends of the steel space frame during the transfer process is as follows: a flexible tube is installed on the large-span spatial steel space frame, and the tube is filled with a colored liquid; the two ends of the tube are fixed on the large-span spatial steel space frame and correspond to the extension lines of two steel wire ropes in sequence; the two ends of the tube are at the same height, a transparent sleeve is fitted on the tube, and a round hole is set at the top of the sleeve to allow the tube to communicate with the atmosphere. A soft cap is set at the top of the sleeve to prevent the liquid from flowing out of the tube when not in operation. A displacement sensor is installed inside the sleeve.

3. The method for overall hoisting and construction of large-span spatial steel space frame using finite element analysis and BIM technology as described in claim 1, characterized in that: A BIM+ resistance strain monitoring system was set up using BIM technology to monitor relevant stress values ​​in real time during the hoisting process. The BIM+ resistance strain monitoring system consists of a sensing layer, a transmission layer, and an application layer. Specifically, it includes a sensor system, a data acquisition subsystem, a data transmission subsystem, a database subsystem, a data processing and control system, and a safety assessment and early warning subsystem. Through the coordination of each layer, the various functions of the system are realized.

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