Safety Detection Methods and Systems for Lifting Large-Span Welded Spherical Steel Space Frames

Abstract

This invention provides a safety detection method and system for the lifting process of a large-span welded spherical steel space frame, belonging to the field of engineering detection technology. The method includes: calculating the simulated deformation and stress values ​​of the large-span welded spherical steel space frame during the lifting process; setting up monitoring points on the large-span welded spherical steel space frame; if the on-site line of sight is greater than the preset line of sight, then using a total station to calculate the elevation values ​​of each monitoring point when the steel space frame is lifted to different heights; otherwise, using a distance measuring instrument to obtain the lifting height of all monitoring points of the steel space frame; calculating various deformation indices and determining whether each deformation indices exceed the corresponding deformation warning value; obtaining the stress change value by combining the strain value obtained by strain gauges with the elastic modulus of the steel material; when the stress change value exceeds the stress change warning value, then partially unloading the steel space frame; this invention comprehensively obtains overall safety performance information, improving the construction safety factor.

Description

Technical Field

[0001] This invention belongs to the field of engineering testing technology, and more specifically, relates to a safety testing method and system for the lifting process of a large-span welded spherical steel space frame. Background Technology

[0002] Steel space frame structures with complex shapes and large spans are widely used in public buildings. Conducting safety performance testing during the lifting construction of irregularly shaped, large-span welded spherical steel space frames, and promptly understanding the stress and deformation of key nodes, is crucial for planned construction guidance and ensuring structural safety.

[0003] However, due to the complex structure, large span, wide monitoring range, and complex site conditions of large-span welded steel space frame, traditional monitoring methods cannot obtain comprehensive overall safety performance information during the steel space frame lifting process due to the dense space frame and site limitations, which reduces the construction safety factor. Therefore, it is necessary to develop a safety performance testing method that combines multiple technical means to solve the existing problems. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a safety detection method and system for the lifting process of large-span welded spherical steel space frame. It aims to solve the problem that the existing large-span welded steel space frame has a complex structure, large span, wide monitoring range and complex site conditions. Therefore, during the lifting process of the steel space frame, due to the dense space frame and site limitations, traditional monitoring methods cannot obtain comprehensive overall safety performance information, which reduces the construction safety factor.

[0005] To achieve the above objectives, on the one hand, the present invention provides a safety detection method during the lifting process of a large-span welded spherical steel space frame, comprising the following steps:

[0006] Using material properties, load conditions, boundary conditions, and load combinations as inputs, a numerical model of a large-span welded spherical steel space frame is constructed to calculate the simulated deformation and stress values ​​of the large-span welded spherical steel space frame during the lifting process.

[0007] Based on the simulated deformation and stress values, monitoring points are set up on the large-span welded spherical steel space frame; in areas where the simulated deformation exceeds the preset deformation and the simulated stress exceeds the preset stress, the spacing between monitoring points is increased.

[0008] To assess the site environment of a large-span welded spherical steel space frame, if the site's visibility is greater than the preset visibility, then use a total station to calculate the elevation values ​​of each monitoring point when the steel space frame is raised to different heights; otherwise, use a rangefinder to obtain the lifting height of all monitoring points on the steel space frame.

[0009] Based on the elevation values ​​of the same monitoring point from multiple azimuths and the lifting height of the same monitoring point multiple times, various deformation indicators are calculated, and it is determined whether each deformation indicator exceeds the corresponding deformation warning value. If so, the lifting method of the large-span welded spherical steel space frame is adjusted.

[0010] Strain gauges were installed along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point.

[0011] The strain value obtained by strain gauges is combined with the elastic modulus of steel to obtain the stress change value;

[0012] The stress change value is compared with the tensile strength and compressive strength of the steel structure material. When the stress change value exceeds the stress change warning value, the large-span welded spherical steel grid is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value.

[0013] When the stress change value at the monitoring point is less than the stress change warning value, and the deformation index is less than the corresponding deformation warning value, the large-span welded spherical steel space frame will be upgraded to the next stage.

[0014] More preferably, the rangefinder measurement method includes the following steps:

[0015] The laser sensor is installed at the bottom of the monitoring point; the laser rangefinder is installed at the center axis of the fixed support with an angle disc, and the ground where the fixed support is located is leveled and checked using a spirit level.

[0016] Among them, the laser rangefinder rotates around the axis of the fixed support to capture the signal of the laser sensor at the bottom of the monitoring point, and reads the rotation angle through the angle disk;

[0017] After the steel grid is pre-lifted, a laser rangefinder is used to align with the laser sensor. The steel grid monitoring point directly in front of the laser rangefinder is used as the reference monitoring point. The initial distance Z0 along the Z direction of the reference monitoring point is measured. The laser rangefinder on the rotating angle disk captures the laser sensor of the steel grid node in the same row and obtains the coordinates (0, S0×cosα, S0×sinα) of the monitoring point in the same row of the steel grid.

[0018] When the steel space frame is raised to the preset height, the benchmark monitoring point Z is measured. 0i The coordinates of the monitoring points of the same row of steel space frame are (0, S1×cosβ, S1×sinβ);

[0019] Calculate the lifting height △Z of the benchmark monitoring point i =Z 0i -Z0, and the lifting height ΔZ of the monitoring network of the same row of steel grid structure. i S' = S1 × sinβ - S0 × sinα;

[0020] Wherein, S0 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the pre-lift is completed; S1 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the preset height is lifted; α is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the pre-lift is completed; β is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the preset height is lifted.

[0021] More preferably, the method for obtaining the elevation values ​​of each monitoring point is as follows:

[0022] a. During the current enhancement phase, align the total station with the two known survey stations at the designated station location and obtain the coordinates of the two survey stations;

[0023] b. Point the total station at the monitoring point, combine the coordinates of the two monitoring stations, calculate the coordinates of the monitoring point, and obtain the distance between the monitoring station and the monitoring point;

[0024] c. Obtain the horizontal distance between the station and the monitoring point based on the angle between them and the distance between them;

[0025] d. Calculate the initial elevation of the monitoring point using plane trigonometric formulas based on the horizontal distance between the site and the monitoring point and the erection height;

[0026] e. When the steel space frame is lifted to different heights, repeat steps a to d, and use a total station to obtain the elevation values ​​of each monitoring point at different lifting stages.

[0027] More preferably, the method for obtaining the stress change value is as follows:

[0028] Three strain gauges are installed at each monitoring point. The strain gauges are glued with silicone along the vertical and horizontal directions. After the silicone dries, the outer surface is fixed with waterproof tape.

[0029] The strain gauge leads are connected to the three-core shielded signal wires via high-temperature ablation.

[0030] After the strain gauges are installed, connect the end of the strain gauge signal line to each signal measurement channel of each wireless dynamic sensor module. Use a wireless communication controller to receive the voltage signals of the strain gauges from the eight channels collected by each wireless dynamic sensor module and convert the voltage signals into digital signals.

[0031] The digital signal is transmitted to a computer terminal for processing and converted into the initial strain value of the strain gauge.

[0032] During the steel frame lifting process, the strain values ​​of each strain gauge component are collected in real time, and the stress change value corresponding to each strain gauge is calculated by comparing the strain change value with the elastic modulus of the steel material.

[0033] The average stress change value corresponding to the three strain gauges at each monitoring point is taken as the stress change value at the monitoring point.

[0034] On the other hand, the present invention provides a safety detection system for the lifting process of a large-span welded spherical steel space frame, comprising:

[0035] The simulation parameter acquisition module is used to construct a numerical model of a large-span welded spherical steel space frame by taking material properties, load conditions, boundary conditions and load combinations as inputs, and to calculate the simulated deformation and simulated stress values ​​of the large-span welded spherical steel space frame during the lifting process;

[0036] The monitoring point deployment module is used to deploy monitoring points on a large-span welded spherical steel space frame based on simulated deformation and simulated stress values; in areas where the simulated deformation exceeds the preset deformation and the simulated stress exceeds the preset stress, the spacing between monitoring points is increased.

[0037] The elevation calculation module is used to calculate the elevation values ​​of each monitoring point when the field line of sight of the large-span welded spherical steel space frame is greater than the preset line of sight. In this case, the total station measurement method is selected to calculate the elevation values ​​of each monitoring point when the steel space frame is raised to different heights.

[0038] The lifting height measurement module is used to obtain the lifting height of all monitoring points of the steel space frame when the on-site line of sight of the large-span welded spherical steel space frame is less than the preset line of sight.

[0039] The deformation judgment module is used to calculate various deformation indicators based on the elevation values ​​of the same monitoring point from multiple directions and the lifting height of the same monitoring point multiple times, and to determine whether each deformation indicator exceeds the corresponding deformation warning value. If so, the lifting method of the large-span welded spherical steel space frame is adjusted.

[0040] The strain gauge placement module is used to place strain gauges along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point.

[0041] The stress change value calculation module is used to obtain the stress change value by combining the strain value obtained by the strain gauge with the elastic modulus of the steel material.

[0042] The stress change value judgment module is used to compare the stress change value with the tensile strength and compressive strength of the steel structure material. When the stress change warning value is exceeded, the large-span welded spherical steel grid is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value.

[0043] The steel space frame lifting determination module is used to lift the large-span welded spherical steel space frame to the next stage when the stress change value at the monitoring point is less than the stress change warning value and the deformation index is less than the corresponding deformation warning value.

[0044] More preferably, the lifting height measurement module includes: a laser sensor, a laser rangefinder, a fixed support, a spirit level, and a lifting height calculation unit;

[0045] The laser sensor is installed at the bottom of the monitoring point; the laser rangefinder is installed on the central axis of the fixed support with an angle disk, and rotates around the axis to capture the signal from the laser sensor at the bottom of the monitoring point, and reads the rotation angle through the angle disk.

[0046] A spirit level is used to level and check the ground where the fixed support is located;

[0047] After the steel grid is pre-lifted, a laser rangefinder is aligned with the laser sensor, and the steel grid sphere directly opposite the laser rangefinder is used as the reference monitoring point. The initial distance Z0 along the Z direction of the reference monitoring point is measured. The coordinates (0, S0×cosα, S0×sinα) of the monitoring points in the same row of steel grid nodes are obtained by rotating the sensor. When the steel grid is lifted to the preset height, the Z0 of the reference monitoring point is measured. 0i The coordinates of the monitoring points of the same row of steel space frame are (0, S1×cosβ, S1×sinβ);

[0048] The lifting height calculation unit is used to calculate the lifting height △Z of the benchmark monitoring point. i =Z 0i -Z0, and the lifting height ΔZ′ of the monitoring network of the same row of steel grid structure. i =S1×sinβ-S0×sinα;

[0049] Wherein, S0 is the distance from the laser rangefinder to the monitoring points in the same row after the pre-lift is completed; S1 is the distance from the laser rangefinder to the monitoring points in the same row after the preset height is lifted; α is the angle between the monitoring points of the steel grid in the same row and the horizontal direction after the pre-lift is completed; β is the angle between the monitoring points of the steel grid in the same row and the horizontal direction after the preset height is lifted.

[0050] More preferably, the elevation calculation module includes: a total station and a data processing unit;

[0051] The total station is used during the current lifting phase to align its station with two known survey stations and obtain their coordinates; it is also used to align with the monitoring point and obtain the angle value and coordinates of the monitoring point.

[0052] The data processing unit is used to calculate the coordinates of the monitoring point based on the angle value and coordinates of the monitoring point, combined with the coordinates of the two measuring stations, and to obtain the distance between the station and the monitoring point; to obtain the horizontal distance between the station and the monitoring point based on the angle between the station and the monitoring point and the distance between the station and the monitoring point; and to calculate the current elevation value of the monitoring point at the lifting stage using plane trigonometric calculation formulas based on the horizontal distance between the station and the monitoring point and the erection height.

[0053] More preferably, the stress change value calculation module includes: strain gauges, silicone, waterproof tape, three-core shielded signal cable, wireless dynamic sensor unit, wireless communication controller, computer terminal and stress change value calculation unit;

[0054] Strain gauges are installed at each monitoring point; silicone is used to attach the strain gauges along the vertical and horizontal directions; waterproof tape is used to fix the outer surface after the silicone has dried;

[0055] The strain gauge leads are connected to the three-core shielded signal line via high-temperature ablation.

[0056] After the strain gauges are installed, the end of the strain gauge signal line is connected to each signal measurement channel of each wireless dynamic sensor unit; the wireless dynamic sensor unit is used to collect the voltage signals of the strain gauges in 8 channels, and the wireless communication controller is used to receive the voltage signals of the strain gauges and convert the voltage signals into digital signals.

[0057] The computer terminal is used to process digital signals and convert them into the initial strain values ​​of the strain gauges;

[0058] The stress change value calculation unit is used to collect the strain values ​​of each strain gauge in the structure during the steel frame lifting process. The stress change value corresponding to each strain gauge is calculated by comparing the strain change value with the elastic modulus of the steel material. The average stress change value of the three strain gauges at each monitoring point is taken as the stress change value at the monitoring point.

[0059] In summary, compared with the prior art, the above-described technical solutions conceived by this invention have the following advantages:

[0060] Beneficial effects:

[0061] This invention provides a safety detection method and system for the lifting process of a large-span welded spherical steel space frame. The safety detection is divided into two categories: deformation monitoring and strain monitoring. In the deformation monitoring process, two situations are considered: if the on-site line of sight is greater than the preset line of sight, the elevation value of each detection point during the lifting process of the steel space frame is calculated using a total station; otherwise, the lifting height of all monitoring points of the steel space frame is obtained using a distance measuring instrument. Various deformation indicators are calculated based on the elevation value or lifting height, and compared with the deformation warning value, thereby continuously adjusting the lifting method of the large-span welded spherical steel space frame during the lifting process. During strain value monitoring, strain gauges are installed along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point. The stress change value is compared with the tensile and compressive strength of the steel structure material. When the stress change warning value is exceeded, the large-span welded spherical steel space frame is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value. This invention can obtain overall safety performance information in all aspects, thus improving the construction safety factor. Attached Figure Description

[0062] Figure 1 This is a flowchart of a safety detection method for lifting a large-span welded spherical steel space frame, provided in an embodiment of the present invention.

[0063] Figure 2 This is a schematic diagram of the monitoring point layout method provided in the embodiment of the present invention;

[0064] Figure 3 This is a schematic diagram illustrating the positional relationship between monitoring points and measuring stations provided in an embodiment of the present invention;

[0065] Figure 4 This is a schematic diagram showing the relationship between the installation site, monitoring point, and installation height provided in an embodiment of the present invention;

[0066] Figure 5 This is an installation diagram of the laser rangefinder provided in an embodiment of the present invention;

[0067] Figure 6 This is a plan view of the strain gauge arrangement provided in an embodiment of the present invention;

[0068] Figure 7 This is a cross-sectional view of the strain gauge arrangement provided in an embodiment of the present invention;

[0069] Marker explanation:

[0070] 1-Welding ball; 2-Phone on welding ball; 3-Surveying station A; 4-Surveying station B; 5-Setting station; 6-Reflector; 7-Connecting extension rod; 8-Laser photosensitive film; 9-Fixed support with angle disc; 10-Laser rangefinder; 11-Plate. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0072] This invention provides a safety detection method for the lifting process of a large-span welded spherical steel space frame. The overall technical solution is as follows:

[0073] A numerical model of a large-span welded spherical steel space frame was established. Using the construction simulation function provided by SAP2000 software, information such as material properties, load conditions, boundary conditions, and load combinations was input to calculate the deformation and stress values ​​of each member and spherical node during the lifting process. Based on the calculation results, the lifting scheme was adjusted to ensure that the maximum deflection value of each span of the steel space frame, the allowable height difference between adjacent lifting points, the maximum height difference, and the stress value of the members were within the warning range, thereby determining a reasonable lifting scheme and the endpoint monitoring location.

[0074] During the actual lifting process, a safety monitoring system for the large-span welded spherical steel space frame is established, including a deformation monitoring system and a stress monitoring system. The safety performance of the large-span welded spherical steel space frame structure is evaluated from three aspects: deformation, internal force, and stability. The actual monitoring values ​​are compared with the warning values. If the warning values ​​are exceeded, the requirements are met by local unloading or adjustment of the lifting point displacement, thereby ensuring construction safety.

[0075] The entire lifting process is divided into two stages: the pre-lifting process and the lifting to the preset height process. The pre-lifting process involves the hydraulic lifter gradually loading the load from 20% to 100% until the entire steel grid structure is 50mm off the ground. The structure is then suspended for 24 hours to check the quality of each connecting component and to install a distance measuring instrument testing system. The lifting to the preset height process involves gradually lifting the structure to the design elevation in stages.

[0076] like Figure 1 As shown, the execution process of the deformation monitoring system in a large-span welded spherical steel space frame is as follows:

[0077] S1: Monitor points are evenly distributed every 15 meters at each lifting point, column top, midpoint of the space frame, and the area between the node and the midpoint of the space frame. At the same time, based on the numerical simulation results, the spacing between monitor points is increased in areas with large calculated deformation.

[0078] Due to the complexity of the construction site for lifting large-span welded spherical steel space frames, traditional total station measurement methods cannot obtain comprehensive information on overall deformation. This invention employs a combined total station and rangefinder measurement technique for monitoring steel space frame deformation. Based on different actual site conditions, the specific steps include:

[0079] S2.1: For areas with open lines of sight that are convenient for setting up instruments, total station measurement method is introduced to collect deformation data;

[0080] S2.1.1: Installation of monitoring points and equipment:

[0081] Based on on-site environmental factors, measurement stations A and B were set up, point O was the instrument station, and point P was the deformation monitoring point for the space frame nodes. Due to the influence of the instrument's line of sight, the relationship between welded sphere 1 and the steel space frame is as follows: Figure 2 As shown, two monitoring point deployment methods are adopted: one is the installation method using a welded ball prism 2; the other is the installation method using a connecting extension rod 7 and a reflector 6.

[0082] S2.1.2: Monitoring steps:

[0083] a. such as Figure 3 As shown, after the steel space frame is pre-lifted, the total station is aligned with the known survey stations A and B at the set station O, and automatically extracts the coordinates of the corresponding survey stations to obtain the coordinates of point A (x, y, y). a y a ) and the coordinates of point B (x b y b Then, align the total station with monitoring point P, and calculate the coordinates (x, y) of monitoring point P using the coordinates of station A and point B. p y p Let the distance between station O and monitoring point P be...

[0084] b. Figure 4 As shown, based on the angle α between the station O and the monitoring point P, the horizontal distance S between the two points and the erection height i, the initial elevation value H of the monitoring point P is calculated using the plane trigonometric calculation formula: H = i + v = i + S tanα.

[0085] c. When the steel space frame is lifted to different heights, according to steps a and b, the elevation values ​​H of each monitoring point at different lifting stages are obtained using a total station. i ;

[0086] S2.2: In areas where dense poles obstruct total station observations, or where site conditions limit the ability to set up a total station, a distance measuring instrument shall be used to obtain deformation data.

[0087] S2.2.1: Installation of monitoring points and equipment:

[0088] A. Installing laser sensor 8 at the deformation monitoring point is to ensure that the rangefinder always collects distance data from the same point at different lifting stages, thereby improving data accuracy;

[0089] B. The laser sensor at the bottom of the upper steel grid monitoring point is fixed with hot melt adhesive and leveled using a spirit level. The lower measuring device uses a laser rangefinder 10 as the main measuring instrument, which is installed on the central axis of a fixed support 9 with an angle disc. The rangefinder can rotate around its axis to capture the signal from the laser sensor at the bottom of the monitoring point, and the rotation angle is read by the angle disc. The fixed support 9 and the pad 11 are fixedly connected by bolts. The upper and lower parts are installed as a unified measuring device, such as... Figure 5 As shown;

[0090] S2.2.2: Measurement steps:

[0091] a. After the steel space frame is pre-lifted, use a laser rangefinder to align with the laser sensor to measure the initial distance of the reference monitoring point along the Z direction as Z0, and define its spatial coordinates as (0,0,Z0). At the same time, measure the coordinates of the monitoring points of the same row of steel space frame as (0,S0×cosα,S0×sinα).

[0092] b. When the steel space frame is raised to a certain height, the distance along the Z-axis from the reference monitoring point is measured as Z. 0i That is, the spatial coordinates are (0,0,Z) 0i Meanwhile, the coordinates of the monitoring points of the same row of steel space frame were measured as (0, S1×cosβ, S1×sinβ);

[0093] c. Calculate the lifting height of all monitoring points of the steel space frame, that is, the lifting height of the steel space frame at the benchmark monitoring point is △Z. i =Z 0i -Z0, the lift height of other nodes is ΔZ′ i =S1×sinβ-S0×sinα;

[0094] Where S0 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the pre-lifting is completed; S1 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the preset height is lifted; α is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the pre-lifting is completed; β is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the preset height is lifted.

[0095] S2.2.3: Data Processing:

[0096] After measuring the elevations of the same point from multiple azimuths using a total station (H1, H2, H3...) and simultaneously measuring the elevations of the same point multiple times using a distance measuring instrument (ΔZ1, ΔZ2, ΔZ3...), the maximum deflection of the space frame, the allowable height difference between two adjacent lifting points, the height difference between the highest and lowest points, and the displacement of the lifting frame at the hoisting point are calculated and compared with the warning values. When any indicator exceeds the limit, the construction party is immediately notified to make on-site adjustments and then retest until all deformation indicators meet the requirements.

[0097] The execution process of the stress monitoring system in a large-span welded spherical steel space frame is as follows:

[0098] D1: Monitoring point location and installation:

[0099] Monitoring points were set up every 15m at the lifting point, the middle of the steel frame, and the area between them. At the same time, based on the data simulation results, the number of monitoring points was increased in the stress concentration area.

[0100] After determining the monitoring locations, foil resistance strain gauges were arranged along the digital axis (vertical) and letter axis (horizontal) on the upper chord, lower chord, and web of the component. To ensure effective data acquisition, three strain gauges were installed at each location. Figure 6 and Figure 7 As shown;

[0101] Use sandpaper to polish the steel surface of the monitoring area to make it smooth. Use silicone to attach the strain gauge along the digital axis or letter axis. After the silicone dries, fix it on the outer surface with waterproof tape to prevent human damage during later construction.

[0102] After the strain gauge is dried, the strain gauge lead wire is connected to the 0.3mm three-core shielded signal wire by high-temperature ablation to prevent interference from other signals. In order to prevent the signal wire from being damaged during the lifting process, all the wires are divided into three strands and packed into the prefabricated ABS tube.

[0103] D2: Test Procedure:

[0104] After the strain gauges are installed, in the initial state, the ends of the strain gauge signal lines are connected to the signal measurement channels of each wireless dynamic sensor unit. The wireless communication controller receives the voltage signals from the eight channels of the strain gauges collected by each unit, converts them into digital signals, and transmits them to the computer terminal via the USB interface. The integrated software processes the acquired digital signals and converts them into the initial strain value ε of each strain gauge. i0 ;

[0105] During the lifting process of the steel space frame, the steel components deform under stress, causing a proportional change in the voltage of the strain gauges connected to them. The integrated software will automatically collect the strain value ε of the component where the strain gauge is located in real time. ii The change in strain value at this location, Δε ii For ε ii -ε i0 The change in its stress value Δσ ii For △ε ii Multiply by the elastic modulus E of the steel material, Δσ ii A positive value indicates that the member is under tension, while a negative value indicates that it is under compression.

[0106] Three strain gauges were arranged along the digital and alphabetical axes of the steel grid at each monitoring point. The average value calculated was used as the representative value of the stress change at that point and compared with the tensile and compressive strength of the steel structure material. If the result exceeded the warning value, local unloading or other methods were required until the stress at the measuring point met the requirements.

[0107] It should be noted that when a large-span steel space frame is lifted to the predetermined height, the safety performance of the steel space frame can only be determined to meet the requirements when both the deformation and stress indicators meet the warning values, and only then can the next stage of lifting work be carried out.

[0108] On the other hand, the present invention provides a safety detection system for the lifting process of a large-span welded spherical steel space frame, comprising:

[0109] The simulation parameter acquisition module is used to construct a numerical model of a large-span welded spherical steel space frame by taking material properties, load conditions, boundary conditions and load combinations as inputs, and to calculate the simulated deformation and simulated stress values ​​of the large-span welded spherical steel space frame during the lifting process;

[0110] The monitoring point deployment module is used to deploy monitoring points on a large-span welded spherical steel space frame based on simulated deformation and simulated stress values; in areas where the simulated deformation exceeds the preset deformation and the simulated stress exceeds the preset stress, the spacing between monitoring points is increased.

[0111] The elevation calculation module is used to calculate the elevation values ​​of each monitoring point when the field line of sight of the large-span welded spherical steel space frame is greater than the preset line of sight. In this case, the total station measurement method is selected to calculate the elevation values ​​of each monitoring point when the steel space frame is raised to different heights.

[0112] The lifting height measurement module is used to obtain the lifting height of all monitoring points of the steel space frame when the on-site line of sight of the large-span welded spherical steel space frame is less than the preset line of sight.

[0113] The deformation judgment module is used to calculate various deformation indicators based on the elevation values ​​of the same monitoring point from multiple directions and the lifting height of the same monitoring point multiple times, and to determine whether each deformation indicator exceeds the corresponding deformation warning value. If so, the lifting method of the large-span welded spherical steel space frame is adjusted.

[0114] The strain gauge placement module is used to place strain gauges along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point.

[0115] The stress change value calculation module is used to obtain the stress change value by combining the strain value obtained by the strain gauge with the elastic modulus of the steel material.

[0116] The stress change value judgment module is used to compare the stress change value with the tensile strength and compressive strength of the steel structure material. When the stress change warning value is exceeded, the large-span welded spherical steel grid is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value.

[0117] The steel space frame lifting determination module is used to lift the large-span welded spherical steel space frame to the next stage when the stress change value at the monitoring point is less than the stress change warning value and the deformation index is less than the corresponding deformation warning value.

[0118] More preferably, the lifting height measurement module includes: a laser sensor, a laser rangefinder, a fixed support, a spirit level, and a lifting height calculation unit;

[0119] The laser rangefinder is installed on the central axis of a fixed support with an angle disc, allowing it to rotate around the axis to capture the signal from the laser sensor at the bottom of the monitoring point. The rotation angle is then read from the angle disc. A spirit level is used to level and check the ground beneath the fixed support.

[0120] The laser rangefinder is used after the steel space frame is pre-lifted. Aligned with the laser sensor, it measures the initial distance Z0 of the reference monitoring point along the Z direction and simultaneously acquires the coordinates (0, S0×cosα, S0×sinα) of the monitoring points in the same row of the steel space frame. The reference monitoring point is a monitoring point with no horizontal displacement. When the steel space frame is lifted to the preset height, the distance Z0 of the reference monitoring point is measured. 0i The coordinates of the monitoring points of the same row of steel space frame are (0, S1×cosβ, S1×sinβ);

[0121] The lifting height calculation unit is used to calculate the lifting height △Z of the benchmark monitoring point. i =Z 0i -Z0, and the lifting height ΔZ′ of the monitoring network of the same row of steel grid structure. i =S1×sinβ-S0×sinα;

[0122] Wherein, S0 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the pre-lift is completed; S1 is the distance from the laser rangefinder to the monitoring point of the same row of steel space frame after the preset height is lifted; α is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the pre-lift is completed; β is the angle between the monitoring point of the same row of steel space frame and the horizontal direction after the preset height is lifted.

[0123] More preferably, the elevation calculation module includes: a total station and a data processing unit;

[0124] The total station is used during the current lifting phase to align its station with two known survey stations and obtain their coordinates; it is also used to align with the monitoring point and obtain the angle value and coordinates of the monitoring point.

[0125] The data processing unit is used to calculate the coordinates of the monitoring point based on the angle value and coordinates of the monitoring point, combined with the coordinates of the two measuring stations, and to obtain the distance between the station and the monitoring point; to obtain the horizontal distance between the station and the monitoring point based on the angle between the station and the monitoring point and the distance between the station and the monitoring point; and to calculate the current elevation value of the monitoring point at the lifting stage using plane trigonometric calculation formulas based on the horizontal distance between the station and the monitoring point and the erection height.

[0126] More preferably, the stress change value calculation module includes: strain gauges, silicone, waterproof tape, three-core shielded signal cable, wireless dynamic sensor unit, wireless communication controller, computer terminal and stress change value calculation unit;

[0127] Strain gauges are installed at each monitoring point; silicone is used to attach the strain gauges along the vertical and horizontal directions; waterproof tape is used to fix the outer surface after the silicone has dried;

[0128] The strain gauge leads are connected to the three-core shielded signal line via high-temperature ablation.

[0129] After the strain gauges are installed, the end of the strain gauge signal line is connected to each signal measurement channel of each wireless dynamic sensor unit; the wireless dynamic sensor unit is used to collect the voltage signals of the strain gauges in 8 channels, and the wireless communication controller is used to receive the voltage signals of the strain gauges and convert the voltage signals into digital signals.

[0130] The computer terminal is used to process digital signals and convert them into the initial strain values ​​of the strain gauges;

[0131] The stress change value calculation unit is used to collect the strain values ​​of each strain gauge in the structure during the steel frame lifting process. The stress change value corresponding to each strain gauge is calculated by comparing the strain change value with the elastic modulus of the steel material. The average stress change value of the three strain gauges at each monitoring point is taken as the stress change value at the monitoring point.

[0132] In summary, compared with the prior art, the present invention has the following advantages:

[0133] This invention provides a safety detection method and system for the lifting process of a large-span welded spherical steel space frame. The safety detection is divided into two categories: deformation monitoring and strain monitoring. In the deformation monitoring process, two situations are considered: if the on-site line of sight is greater than the preset line of sight, the elevation value of each detection point during the lifting process of the steel space frame is calculated using a total station; otherwise, the lifting height of all monitoring points of the steel space frame is obtained using a distance measuring instrument. Various deformation indicators are calculated based on the elevation value or lifting height, and compared with the deformation warning value, thereby continuously adjusting the lifting method of the large-span welded spherical steel space frame during the lifting process. During strain value monitoring, strain gauges are installed along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point. The stress change value is compared with the tensile and compressive strength of the steel structure material. When the stress change warning value is exceeded, the large-span welded spherical steel space frame is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value. This invention can obtain overall safety performance information in all aspects, thus improving the construction safety factor.

[0134] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A safety detection method for the lifting process of a large-span welded spherical steel space frame, characterized in that, Includes the following steps: Using material properties, load conditions, boundary conditions, and load combinations as inputs, a numerical model of a large-span welded spherical steel space frame is constructed to calculate the simulated deformation and stress values ​​of the large-span welded spherical steel space frame during the lifting process. Based on the simulated deformation and stress values, monitoring points are set up on the large-span welded spherical steel space frame; in areas where the simulated deformation exceeds the preset deformation and the simulated stress exceeds the preset stress, the spacing between monitoring points is increased. To assess the site environment of a large-span welded spherical steel space frame, if the site's visibility is greater than the preset visibility, then use a total station to calculate the elevation values ​​of each monitoring point when the steel space frame is raised to different heights; otherwise, use a rangefinder to obtain the lifting height of all monitoring points on the steel space frame. Based on the elevation values ​​of the same monitoring point from multiple azimuths and the lifting height of the same monitoring point multiple times, various deformation indicators are calculated, and it is determined whether each deformation indicator exceeds the corresponding deformation warning value. If so, the lifting method of the large-span welded spherical steel space frame is adjusted. Strain gauges were installed along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point. The strain value obtained by strain gauges is combined with the elastic modulus of steel to obtain the stress change value; The stress change value is compared with the tensile strength and compressive strength of the steel structure material. When the stress change value exceeds the stress change warning value, the large-span welded spherical steel grid is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value. When the stress change value at the monitoring point is less than the stress change warning value, and the deformation index is less than the corresponding deformation warning value, the large-span welded spherical steel space frame will be upgraded to the next stage. The distance measuring method includes the following steps: Install a laser sensor at the bottom of the monitoring point, install the laser rangefinder at the center axis of the fixed support with an angle disc, and use a spirit level to level and check the ground where the fixed support is located. Among them, the laser rangefinder rotates around the axis of the fixed support to capture the signal of the laser sensor at the bottom of the monitoring point, and reads the rotation angle through the angle disk; After the steel grid is pre-lifted, a laser rangefinder is used to align with the laser sensor. The steel grid monitoring point directly opposite the laser rangefinder is used as the reference monitoring point. The initial distance Z0 along the Z direction of the reference monitoring point is measured. The laser rangefinder on the rotating angle disk captures the laser sensor installed at the bottom of other monitoring points of the same row of steel grid, and obtains the coordinates (0, S0×cosα, S0×sinα) of other monitoring points of the same row of steel grid. When the steel space frame is raised to the preset height, the benchmark monitoring point Z is measured. 0i The coordinates of the monitoring points of the same row of steel space frame are (0, S1×cosβ, S1×sinβ). Calculate the lifting height △Z of the benchmark monitoring point i =Z 0i -Z0, and the lifting height of the steel grid monitoring network in the same row. ; Wherein, S0 is the distance from the laser rangefinder to the monitoring points in the same row after the pre-lift is completed; S1 is the distance from the laser rangefinder to the monitoring points in the same row after the preset height is raised; α is the angle between the monitoring points in the same row and the horizontal direction after the pre-lift is completed; β is the angle between the monitoring points in the same row and the horizontal direction after the preset height is raised.

2. The security detection method according to claim 1, characterized in that, The method for obtaining the elevation values ​​of each monitoring point is as follows: a. During the current enhancement phase, align the total station with the two known survey stations at the designated station location and obtain the coordinates of the two survey stations; b. Point the total station at the monitoring point, and calculate the coordinates of the monitoring point by combining the coordinates of the two monitoring stations, and obtain the distance between the monitoring station and the station. c. Obtain the horizontal distance between the station and the monitoring point based on the angle between them and the distance between them; d. Based on the horizontal distance between the station and the monitoring point and the erection height, calculate the current elevation value of the monitoring point during the lifting stage using the plane trigonometric calculation formula; e. When the steel space frame is lifted to different heights, repeat steps a~d and use a total station to obtain the elevation values ​​of each monitoring point at different lifting stages.

3. The security detection method according to claim 1 or 2, characterized in that, The method for obtaining stress change values ​​is as follows: Install three strain gauges at each monitoring point. Adhere the strain gauges with silicone along the vertical and horizontal directions. After the silicone dries, fix them to the outer surface with waterproof tape. The strain gauge leads are connected to the three-core shielded signal wires via high-temperature ablation. After the strain gauges are installed, connect the end of the strain gauge signal line to each signal measurement channel of each wireless dynamic sensor unit. Use a wireless communication controller to receive the voltage signals of the strain gauges from the eight channels collected by each wireless dynamic sensor unit and convert the voltage signals into digital signals. The digital signal is transmitted to a computer terminal for processing and converted into the initial strain value of the strain gauge. During the steel frame lifting process, the strain values ​​of each strain gauge in the structure are collected in real time, and the stress change value corresponding to each strain gauge is calculated by the strain change value and the elastic modulus of the steel material. The average stress change value corresponding to the three strain gauges at each monitoring point is taken as the stress change value at the monitoring point.

4. A safety detection system for the lifting process of a large-span welded spherical steel space frame, characterized in that, include: The simulation parameter acquisition module is used to construct a numerical model of a large-span welded spherical steel space frame by taking material properties, load conditions, boundary conditions and load combinations as inputs, and to calculate the simulated deformation and simulated stress values ​​of the large-span welded spherical steel space frame during the lifting process; The monitoring point deployment module is used to deploy monitoring points on a large-span welded spherical steel space frame based on simulated deformation and simulated stress values; in areas where the simulated deformation exceeds the preset deformation and the simulated stress exceeds the preset stress, the spacing between monitoring points is increased. The elevation calculation module is used to calculate the elevation values ​​of each monitoring point when the field line of sight of the large-span welded spherical steel space frame is greater than the preset line of sight. In this case, the total station measurement method is selected to calculate the elevation values ​​of each monitoring point when the steel space frame is raised to different heights. The lifting height measurement module is used to obtain the lifting height of all monitoring points of the steel space frame when the on-site line of sight of the large-span welded spherical steel space frame is less than the preset line of sight. The deformation judgment module is used to calculate various deformation indicators based on the elevation values ​​of the same monitoring point from multiple directions and the lifting height of the same monitoring point multiple times, and to determine whether each deformation indicator exceeds the corresponding deformation warning value. If so, the lifting method of the large-span welded spherical steel space frame is adjusted. The strain gauge placement module is used to place strain gauges along the horizontal and vertical directions on the upper chord, lower chord, and web members of the large-span welded spherical steel space frame corresponding to each monitoring point. The stress change value calculation module is used to obtain the stress change value by combining the strain value obtained by the strain gauge with the elastic modulus of the steel material. The stress change value judgment module is used to compare the stress change value with the tensile strength and compressive strength of the steel structure material. When the stress change warning value is exceeded, the large-span welded spherical steel grid is partially unloaded until the stress change value at the monitoring point is less than the stress change warning value. The steel space frame lifting determination module is used to lift the large-span welded spherical steel space frame to the next stage when the stress change value at the monitoring point is less than the stress change warning value and the deformation index is less than the corresponding deformation warning value. The lifting height measurement module includes: a laser sensor, a laser rangefinder, a fixed support, a spirit level, and a lifting height calculation unit; The laser sensor is installed at the bottom of the monitoring point; the laser rangefinder is installed on the central axis of a fixed support with an angle disk and rotates around the axis; it is used to capture the signal from the laser sensor at the bottom of the monitoring point and read the rotation angle through the angle disk; A spirit level is used to level and check the ground where the fixed support is located; The laser rangefinder is used after the steel space frame is pre-lifted. Aligned with the laser sensor, it measures the initial distance Z0 of the reference monitoring point along the Z direction and obtains the coordinates (0, S0×cosα, S0×sinα) of the monitoring points in the same row by rotation. The reference monitoring point is the steel space frame monitoring point directly opposite the laser rangefinder. When the steel space frame is lifted to the preset height, the distance Z0 of the reference monitoring point is measured. 0i The coordinates of other monitoring points in the same row (0, S1×cosβ, S1×sinβ); The lifting height calculation unit is used to calculate the lifting height △Z of the benchmark monitoring point. i =Z 0i -Z0, and the lifting height of the steel grid monitoring network in the same row. ; Wherein, S0 is the distance from the laser rangefinder to the monitoring points in the same row after the pre-lift is completed; S1 is the distance from the laser rangefinder to the monitoring points in the same row after the preset height is lifted; α is the angle between the monitoring points of the steel grid in the same row and the horizontal direction after the pre-lift is completed; β is the angle between the monitoring points of the steel grid in the same row and the horizontal direction after the preset height is lifted.

5. The security detection system according to claim 4, characterized in that, The elevation calculation module includes: a total station and a data processing unit; The total station is used during the current lifting phase to align its station with two known survey stations and obtain their coordinates; it is also used to align with the monitoring point and obtain the angle value and coordinates of the monitoring point. The data processing unit is used to calculate the coordinates of the monitoring point based on the angle value and coordinates of the monitoring point, combined with the coordinates of the two measuring stations, and to obtain the distance between the station and the monitoring point; to obtain the horizontal distance between the station and the monitoring point based on the angle between the station and the monitoring point and the distance between the station and the monitoring point; and to calculate the current elevation value of the monitoring point at the lifting stage using plane trigonometric calculation formulas based on the horizontal distance between the station and the monitoring point and the erection height.

6. The security detection system according to claim 4 or 5, characterized in that, The stress change value calculation module includes: strain gauges, silicone, waterproof tape, three-core shielded signal cable, wireless dynamic sensor unit, wireless communication controller, computer terminal, and stress change value calculation unit; Strain gauges are installed at each monitoring point; silicone is used to attach the strain gauges along the vertical and horizontal directions; waterproof tape is used to fix the outer surface after the silicone has dried; The strain gauge leads are connected to the three-core shielded signal line via high-temperature ablation. After the strain gauges are installed, the end of the strain gauge signal line is connected to each signal measurement channel of each wireless dynamic sensor unit; the wireless dynamic sensor unit is used to collect the voltage signals of the strain gauges in 8 channels, and the wireless communication controller is used to receive the voltage signals of the strain gauges and convert the voltage signals into digital signals. The computer terminal is used to process digital signals and convert them into the initial strain values ​​of the strain gauges; The stress change value calculation unit is used to collect the strain values ​​of each strain gauge in the structure during the steel frame lifting process. The stress change value corresponding to each strain gauge is calculated by comparing the strain change value with the elastic modulus of the steel material. The average stress change value of the three strain gauges at each monitoring point is taken as the stress change value at the monitoring point.

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