Temperature difference performance testing system and method for cold-bending hollow glass curtain wall

Abstract

The invention discloses a temperature difference performance test system and method for a cold-bending hollow glass curtain wall. A support and a cold-bending frame of the test system are used for accurately cold-bending hollow glass to a design curvature; the temperature difference simulation loading subsystem comprises a frame cage which can cover the outside of a glass room and has heat preservation and heating functions, and a set of device for spraying water to cool the outside of the glass room, and is used for simulating the working conditions of extreme sunlight heating and sudden rain cooling experienced by the glass in the service process; the data acquisition monitoring subsystem is used for monitoring the strain, deflection and surface temperature of the glass in the heating and cooling processes in real time; the central control system is used for controlling the heating and cooling process and collecting data. The testing method comprises the steps of cold roll forming, graded heating and constant-temperature testing and rapid cooling testing after high temperature. The thermal shock resistance of the cold-bending hollow glass in a complex temperature field and the safety of the cold-bending hollow glass under temperature stress are effectively evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building curtain wall engineering detection, and particularly relates to a temperature difference performance test system and method for cold-bent hollow glass curtain walls, which simulates the temperature change conditions of the glass curtain wall under the action of solar radiation and rainwater cooling in a service environment, and tests the structural reliability and safety of the glass curtain wall. BACKGROUND

[0002] Hollow glass curtain walls are widely used due to their excellent heat preservation and insulation performance. However, under strong sunlight, the surface temperature of the glass can reach 60-80 DEG C, and sudden rain can cause the surface temperature of the glass to drop sharply by tens of degrees in a few minutes. Such rapid and drastic temperature changes can generate a large temperature gradient inside the glass, thereby causing significant thermal stress. For cold-bent glass, there is an initial pre-stress inside the glass, and after the temperature stress is superimposed, the stress state is more complex, and there is a risk of rupture due to thermal stress exceeding the bearing limit.

[0003] At present, the test of glass curtain walls is mainly concentrated on mechanical loads such as wind pressure, and there is still a lack of standard test methods and special equipment for systematic temperature difference performance tests of cold-bent hollow glass, especially for temperature loads. The traditional temperature chamber test cannot simulate the heating and cooling conditions of one side, and cannot be combined with the cold-bending process. Therefore, it is of great importance to develop a test system and method that can truly simulate the heating and cooling process of cold-bent hollow glass in the actual environment and accurately measure the mechanical response of the glass, so as to ensure the safety and durability of the curtain wall structure and promote the application of cold-bent glass technology. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to solve the following technical problems: 1. The temperature difference test is directly carried out after the glass is cold-bent, and the process is closely connected.

[0005] 2. The extreme conditions of the glass being heated by solar radiation on the outdoor side and being cooled by rainwater spraying are simulated.

[0006] 3. The stress, deformation and temperature field data of the glass during the temperature change process are monitored and recorded throughout the process, thereby providing accurate basis for safety evaluation.

[0007] To solve the above technical problems, the present application adopts the following technical scheme: a temperature difference performance test system for cold-bent hollow glass curtain walls, comprising: A support and cold bending frame is used to fix the insulating glass specimen and elastically cold bend it from a flat state to the target curvature. A pair of long side members of the support and cold bending frame are provided with multiple fastening mechanisms that can be independently and graded. The insulating glass specimen is bent and the boundary is locked by non-uniform vertical displacement, thereby providing a stable and reproducible initial mechanical state for subsequent temperature difference testing. The temperature difference simulation loading subsystem includes: An insulated frame cage is placed over the outside of the glass enclosure to reduce heat loss. The heating device, located inside the insulated frame cage, is used to radiate heat to the exterior of the glass room to simulate solar radiation. The cooling device is used to spray water evenly and completely over the exterior of the glass window after heating, in order to simulate the cooling effect of heavy rain. Temperature sensor used to collect the temperature of the inner and outer surfaces of the glass in real time; The data acquisition and monitoring subsystem includes: Triaxial strain rosettes are arranged at key measuring points on the interior and exterior surfaces of the glass chamber to obtain linear strain in the 0°, 45°, and 90° directions and calculate principal stresses. Displacement gauges are used to monitor the thermal bending deformation of glass; The central control system is communicatively connected to the heating device, cooling device, temperature sensor, triaxial strain gauge and displacement meter, and is used to execute the heating-constant temperature-cooling staged loading and holding program, and automatically collect and process data to generate reports.

[0008] The fastening mechanism consists of high-strength bolts arranged at equal intervals along the flange of the long side component, and displacement control is achieved by tightening / loosening in stages.

[0009] The heating device consists of multiple high-power infrared heating lamps, which are evenly installed below the top surface of the insulated frame cage, and their illumination area completely covers the outside of the glass room.

[0010] The cooling device is a water pipe-nozzle array, with the nozzles and infrared heating lamps arranged in a staggered manner to avoid water-electricity contact.

[0011] The triaxial strain rosette is attached to the mid-span, quarter-span, edges, and corners of the glass to calculate the first principal stress at any point on the glass surface. σ 1 and the third principal stress σ.

[0012] The method for testing the temperature difference performance of cold-bent insulated glass curtain walls in the system includes the following steps: S100 Cold Bending Forming: The graded adjustment and fastening mechanism allows the insulating glass specimen to be cold-bent to the preset arch height and lock the boundary; S200 graded heating and isothermal test: Cover with an insulated frame cage, start the heating device, raise the temperature of the outer surface of the glass to the target high temperature according to the preset graded heating system and keep it constant, and record the strain and displacement response of the glass at each temperature. S300 High Temperature Rapid Cooling Test: After the constant temperature period ends, the cooling device is immediately activated to continuously spray water on the outside of the glass, so that the surface temperature of the glass drops to room temperature within a few minutes, forming a thermal shock. S400 Data Analysis and Safety Assessment: Based on the collected temperature, strain, and displacement data, the maximum thermal stress is calculated and compared with the allowable strength of the glass to determine the glass's resistance to temperature shock. The stress state of the glass surface is determined by measuring the linear strain in three directions using a strain testing system, and then the first principal stress is calculated using formula (1). σ 1 and the third principal stress σ 3. Used to analyze the stress distribution during the temperature difference test of cold-bent glass. , in the formula E For elastic modulus, µ It is Poisson's ratio.

[0013] The preset arch height is 1.5-2 times the designed arch height, and is used to verify overload conditions.

[0014] The graded heating system divides the target high temperature into at least 8 levels, with each level increasing by 5°C and held at that temperature for 5 minutes.

[0015] The rapid cooling test requires the temperature to drop from 60°C to 20°C in no more than 10 minutes.

[0016] The safety assessment uses the absence of cracks in the glass and the maximum thermal stress being below the allowable strength as the criteria for acceptance.

[0017] The innovative aspects of this invention will be further explained below.

[0018] The innovative aspects of the testing system are: Support and cold-bending frame: Used to fix the insulated glass specimen throughout the test. The main body of the frame is constructed of steel profiles, and its core feature is a precision displacement control mechanism installed on a pair of long-side members. This mechanism consists of a series of independently adjustable, graded fasteners. By precisely controlling the screw-in amount of these fasteners, a preset, non-uniform vertical displacement can be applied to the long sides of the glass specimen, thereby accurately and elastically bending the insulated glass specimen to the target curvature and arch height required by the design, and providing a stable and reproducible initial mechanical state for subsequent temperature difference testing.

[0019] Temperature difference simulation loading subsystem: This subsystem is responsible for simulating the real temperature environment.

[0020] Insulated frame cage: A welded steel frame structure covering the outside of the glass exterior, with high-efficiency insulation material wrapped around its exterior. The insulation material must cover the outer edge of the inner surface of the glass interior to ensure a high-temperature environment is created when heating is applied to the outer surface of the glass exterior, thereby reducing heat loss.

[0021] Heating device: preferably multiple high-power infrared heating lamps, evenly installed below the top surface of the insulation frame cage, to simulate the heating effect of solar radiation on the glass, and its illumination area must completely cover the outside of the glass.

[0022] Cooling device: A spray system consisting of water pipes and multiple nozzles can spray water evenly and completely over the high-temperature glass exterior under command, simulating the cooling effect of summer rain on glass and creating a strong thermal shock.

[0023] Temperature sensors: Multiple high-precision thermocouples or infrared thermometers are arranged on the inner and outer surfaces of the glass to monitor and control temperature changes in real time.

[0024] Data acquisition and monitoring subsystem: This is a distributed sensor network.

[0025] (a) Strain monitoring: Based on the stress analysis results, triaxial strain rosettes are densely attached to key points on the indoor and outdoor surfaces of the glass, such as mid-span, quarter-span, edges, and corners. These strain rosettes can measure linear strain in three directions, and the magnitude and direction of the principal stress at each point can be calculated using material mechanics formulas.

[0026] (b) Displacement monitoring: Large-range, high-precision displacement gauges, such as LVDTs, are installed on the inner surface of the glass room to monitor the thermal bending deformation of the glass caused by temperature changes in real time.

[0027] Central control system: Consists of a computer, data acquisition card, and control software. The software pre-programs standard test procedures, such as heating regime and holding time, and collects data from all sensors.

[0028] The innovation of the testing method lies in: S100, Cold Bending Forming Step: This step aims to prepare curved glass specimens with a stable initial stress state for temperature difference testing. The insulating glass specimen is installed on the support and cold bending frame, and then the fastening bolts are adjusted step-by-step according to a preset grading system using its precision displacement control mechanism. After each displacement loading step, the process is paused to check the glass condition and record strain data. When the target arch height is reached, typically 1.5 to 2 times the design value, all fastening mechanisms are locked to firmly lock the glass shape, providing a reliable mechanical basis for subsequent temperature stress research.

[0029] S200, Stepped Heating and Constant Temperature Test Procedure: Cover with the insulated frame cage and start the heating device. Employ a stepped heating and short-term constant temperature regime to allow the glass to slowly and evenly absorb heat, while observing the glass's response at each temperature level.

[0030] Rapid cooling test procedure after high temperature: This is the most rigorous test phase. Once the outer surface of the glass reaches the preset maximum temperature, such as 60°C, it is maintained for a period of time to simulate continuous scorching at midday. Subsequently, the water spray device is immediately activated to continuously and rapidly cool the incandescent glass, simulating a sudden rainstorm, while maintaining a constant temperature throughout the process.

[0031] S400: Data Analysis and Safety Assessment Steps: Analyze data throughout the entire thermal cycle. Focus on whether the maximum thermal stress exceeds the glass's allowable strength; whether the glass develops cracks or permanent damage. Based on this data, make a safety assessment of the glass's resistance to temperature shock.

[0032] Compared with the prior art, the present invention has the following significant advantages: Highly realistic working condition simulation: For the first time, cold bending, insulation, radiant heating and water spray cooling are integrated into one, perfectly reproducing the most severe temperature impact scenarios faced by glass curtain walls in real environment. Its core lies in building a comprehensive test environment that integrates cold bending, heating, insulation and cooling functions.

[0033] Comprehensive and accurate test parameters: It can simultaneously acquire the coupling relationship between temperature, thermal stress, and deformation.

[0034] A more comprehensive safety assessment: The glass's dynamic crack resistance was tested through a "thermal shock" test, making the assessment more comprehensive.

[0035] High degree of automation: The entire heating and cooling process is controlled by a program, resulting in good repeatability and high reliability of test results. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the left view of the system during the temperature rise test.

[0037] Figure 2 This is a side view cross-sectional diagram of the system under water spray cooling test conditions.

[0038] Figure 3 This is a detailed diagram illustrating the principle of how the fastening mechanism bolts apply displacement to the glass during the cold bending process.

[0039] Figure 4 This is a diagram showing the stress change at the center of the glass during the heating test in the embodiment.

[0040] Explanation of reference numerals in the attached drawings: 1. Support and cold bending frame; 2. Insulating glass specimen; 3. Fastening mechanism; 4. Rubber strip; 5. Insulation frame cage; 6. Heating device; 7. Cooling device; 8. Insulation material; 9. Displacement gauge; 10. Triaxial strain gauge; 11. Temperature sensor; 12. Central control system. Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0042] This embodiment describes a temperature difference performance testing system for a cold-bent insulated glass curtain wall according to the present invention, comprising: a support and cold-bending frame 1, an insulated glass specimen 2, a fastening mechanism 3, a rubber strip 4, an insulation frame cage 5, a heating device 6, a cooling device 7, insulation material 8, a displacement gauge 9, a triaxial strain gauge 10, a temperature sensor 11, and a central control system 12. The specific structure and connection relationships are as follows: The main body of the support and cold-bending frame 1 is constructed of steel profiles, and its core feature is a precision displacement control mechanism installed on a pair of long-side members. This mechanism consists of a series of independently adjustable, graded high-strength fastening mechanisms 3. By precisely controlling the screw advance of these fastening mechanisms 3, a preset, non-uniform vertical displacement can be applied to the long side of the insulating glass specimen 2, thereby accurately and elastically bending the insulating glass specimen 2 to the target curvature and arch height required by the design, and providing a stable and reproducible initial mechanical state for subsequent temperature difference testing.

[0043] 1. Temperature Difference Simulation Loading Subsystem: This subsystem is responsible for simulating real-world temperature environments. Insulated frame cage 5: A welded steel frame structure covering the outside of the glass door, with insulation material 8 wrapped around its outside. The insulation material 8 needs to cover the outer edge of the inner surface of the glass door to ensure that a high-temperature environment is created when heating the outer surface of the glass door, thereby reducing heat loss. Heating device 6: It is evenly installed below the top surface of the insulation frame cage 5 to simulate the heating effect of solar radiation on the glass. Its illumination area must completely cover the outside of the glass. Cooling device 7: A spray system consisting of water pipes and multiple nozzles can spray water evenly and completely over the high-temperature glass exterior under command, simulating the cooling effect of summer rainstorms on glass and creating a strong thermal shock. Temperature sensor 11: Composed of multiple high-precision thermocouples or infrared thermometers, arranged on the inner and outer surfaces of the glass, used for real-time monitoring and control of temperature change processes.

[0044] 2. Data Acquisition and Monitoring Subsystem: This is a distributed sensor network. Triaxial strain rosette 10: Based on stress analysis results, triaxial strain rosette 10 are densely attached to key points such as mid-span, quarter-span, edges, and corners on the indoor and outdoor surfaces of the glass. These triaxial strain rosette 10 can measure linear strain in three directions, and the magnitude and direction of the principal stress at each point can be calculated using material mechanics formulas. Displacement gauge 9: Large-range, high-precision displacement gauges (LVDTs) are installed on the inner surface of the glass chamber to monitor the thermal bending deformation of the glass caused by temperature changes in real time.

[0045] 3. Central Control System 12: Composed of a computer, data acquisition card, and control software. The software pre-sets standard test procedures, such as heating regime and isothermal time, and collects data from all sensors.

[0046] Because the stress state of cold-bent glass surface is complex and the directions of principal stress and principal strain on each surface are unknown, the linear strain in three directions is measured by a strain testing system, and then the first principal stress is calculated by formula (1). σ 1 and the third principal stress σ 3. Used to analyze the stress distribution law during the temperature difference test of cold-bent glass.

[0047] , in the formula E The elastic modulus is 72 GPa. µ The ratio is Poisson's ratio (0.2).

[0048] Example 2 This embodiment is an application example of the temperature difference performance testing method for cold-bent insulated glass curtain walls described in this invention, and includes the following steps: The test subject is the cold-formed insulated glass to be used in the T3 terminal building project of Nanning Wuxu International Airport. The glass structure is "HS10+1.52PVB+HS10 Triple Silver Low-E+12Ar+TP12mm" insulated laminated tempered / semi-tempered ultra-clear glass, with planar dimensions of 3000mm wide × 2100mm high. The radius of the glass after cold bending is 22.5m, the cold bending arch height is 50mm, and the designed cold bending arch height is 25mm; the indoor temperature is 20℃, and the simulated maximum temperature is 60℃.

[0049] 1. System preparation and test piece installation: a. Construct a steel support frame with a load-bearing capacity exceeding 50kN. Install high-strength bolts at the same height on the lower flange of the frame, and lay 80mm wide and 20mm thick rubber strips.

[0050] b. Carefully hoist the glass specimen and place it flat on the rubber pad, with the outer surface of the glass facing upwards.

[0051] c. Place rubber strip 4 on the upper surface of the long side of the glass, and then install the high-strength bolts on the upper flange. In the initial state, all bolts are slightly tightened, only for positioning.

[0052] 2. Cold bending forming: a) Cold bending was performed using the displacement control method. The target test arch height was set at 50mm, twice the design value, to verify the overload capacity.

[0053] b) A graded loading system is set through the central control system: a total of 10 levels, with a mid-span displacement increment of 5mm for each level. At the same time, to ensure that the glass has a smooth arc shape, the system automatically calculates and controls the displacement at the 1 / 4 and 3 / 4 long sides to satisfy the sinusoidal half-wave curve relationship with the mid-span displacement. For example, when the mid-span displacement is 5mm, the displacement at the 1 / 4 and 3 / 4 points is 3.5mm.

[0054] c) Tighten the bolts step by step according to the procedure. After each step is completed, hold the load for 5 minutes, observe and record the preliminary strain data.

[0055] d) Stop loading when the mid-span displacement reaches 50mm. Tighten all bolts to the predetermined torque to lock the glass boundary. Let stand for 1 hour and observe that there is no change in the arch height to confirm that the cold bending forming is complete.

[0056] 3. Measurement point layout: On the indoor and outdoor surfaces of the glass, a total of 30 triaxial 0°-45°-90° strain flowers are arranged at key locations such as the quarter point of the long side and the half point of the short side, with 15 flowers on each surface; Nine displacement gauges were evenly arranged on the interior of the glass room to monitor the deflection in the mid-span area.

[0057] 4. Install a temperature difference loading device: An insulated frame cage 5 is placed over the exterior of the cold-bent glass, and heating devices 6 are evenly installed below the top of the cage. The outside of the cage is covered with insulation material 8. Sprinklers 7 are arranged below the top of the insulation frame cage 5 and connected to the water supply system. The sprinklers must be below the heating device 6 and staggered from it to avoid water and electricity contact causing safety problems. Three waterproof temperature sensors are evenly arranged on the exterior of the glass room.

[0058] 5. Graded heating and constant temperature test: The initial temperature is room temperature (20℃). A tiered temperature increase regime is set: each tier increases by 5℃, and each tier is held at the same temperature for 5 minutes.

[0059] The central control system is activated, and it controls the power of the heating lamps according to the system's settings, gradually raising the outdoor temperature of the glass to 25℃, 30℃, ... 60℃. Data is recorded and the glass condition is observed during the 5-minute period at each temperature plateau.

[0060] Observation results: No cracks were generated on the inner and outer surfaces of the glass throughout the entire heating and constant temperature process.

[0061] 6. Data Analysis and Security Assessment S400: Observation: The glass remained intact throughout the entire test; Stress analysis: All calculated maximum thermal stress values ​​are far below the allowable strength of this type of glass material. When there is a temperature difference ΔT = T between the upper and lower surfaces of a beam or plate... 上 -T 下 At this time, bending deformation and bending stress will occur;

[0062] Safety assessment: Based on the fact that the glass was not damaged, the cold-bent insulating glass specimen is judged to have good resistance to temperature shock and meet the safety requirements for temperature difference performance.

[0063] Example 3 This embodiment is an application example of the temperature difference performance testing method for cold-formed insulated glass curtain walls described in this invention. Following the approach used in Example 2 for the Nanning Wuxu International Airport Terminal 3 project, a rapid cooling test was conducted after the temperature was raised to the rated high temperature and kept constant. The test included the following steps: 1. Rapid cooling test after high temperature: Once the temperature reaches 60℃ and 10 minutes of final constant temperature control are completed, immediately activate cooling device 7 to continuously spray water to cool the exterior of the glass room. By spraying water, the surface temperature of the glass is rapidly and continuously reduced from 60°C to room temperature of 20°C. Observation results: When subjected to sudden cooling by water spray, a large amount of steam was generated on the glass surface and the temperature dropped rapidly. There were no cracks or damage during or after the process.

[0064] 2. Data Analysis and Security Assessment: a. Observation of the phenomenon: The glass remained intact throughout the entire test.

[0065] b. Stress analysis: All the calculated maximum thermal stress values ​​are far below the allowable strength of this type of glass material.

[0066] c. Safety assessment: Based on the fact that the glass was not damaged, the cold-bent insulating glass specimen is judged to have good resistance to temperature shock and meet the safety requirements for temperature difference performance.

Claims

1. A temperature difference performance testing system for cold-formed insulated glass curtain walls, characterized in that, include: A support and cold bending frame is used to fix the insulating glass specimen and elastically cold bend it from a flat state to the target curvature. A pair of long side members of the support and cold bending frame are provided with multiple fastening mechanisms that can be independently and graded. The insulating glass specimen is bent and the boundary is locked by non-uniform vertical displacement, thereby providing a stable and reproducible initial mechanical state for subsequent temperature difference testing. The temperature difference simulation loading subsystem includes: An insulated frame cage is placed over the outside of the glass enclosure to reduce heat loss. The heating device, located inside the insulated frame cage, is used to radiate heat to the exterior of the glass room to simulate solar radiation. The cooling device is used to spray water evenly and completely over the exterior of the glass window after heating, in order to simulate the cooling effect of heavy rain. Temperature sensor used to collect the temperature of the inner and outer surfaces of the glass in real time; The data acquisition and monitoring subsystem includes: Triaxial strain rosettes are arranged at key measuring points on the interior and exterior surfaces of the glass chamber to obtain linear strain in the 0°, 45°, and 90° directions and calculate principal stresses. Displacement gauges are used to monitor the thermal bending deformation of glass; The central control system is communicatively connected to the heating device, cooling device, temperature sensor, triaxial strain gauge and displacement meter, and is used to execute the heating-constant temperature-cooling staged loading and holding program, and automatically collect and process data to generate reports.

2. The system according to claim 1, wherein the fastening mechanism is a high-strength bolt equidistantly arranged along the flange of the long side member, and displacement control is achieved by graded tightening / loosening.

3. The system according to claim 1, wherein the heating device comprises multiple high-power infrared heating lamps, which are evenly installed below the top surface of the insulation frame cage, and their illumination area completely covers the outside of the glass room.

4. The system according to claim 1, wherein the cooling device is a water pipe-nozzle array, and the nozzles and infrared heating lamps are arranged in a staggered manner to avoid water-electricity contact.

5. The system according to claim 1, wherein the triaxial strain rosette is attached to the mid-span, quarter-span, edge, and corner of the glass for calculating the first principal stress at any point on the glass surface. σ 1 and the third principal stress σ 3.

6. A method for testing the temperature difference performance of a cold-formed insulated glass curtain wall using the system described in any one of claims 1-5, characterized in that, Includes the following steps: S100 Cold Bending Forming: The graded adjustment and fastening mechanism allows the insulating glass specimen to be cold-bent to the preset arch height and lock the boundary; S200 graded heating and isothermal test: Cover with an insulated frame cage, start the heating device, raise the temperature of the outer surface of the glass to the target high temperature according to the preset graded heating system and keep it constant, and record the strain and displacement response of the glass at each temperature. S300 High Temperature Rapid Cooling Test: After the constant temperature period ends, the cooling device is immediately activated to continuously spray water on the outside of the glass, so that the surface temperature of the glass drops to room temperature within a few minutes, forming a thermal shock. S400 Data Analysis and Safety Assessment: Based on the collected temperature, strain, and displacement data, the maximum thermal stress is calculated and compared with the allowable strength of the glass to determine the glass's resistance to temperature shock. The stress state of the glass surface is determined by measuring the linear strain in three directions using a strain testing system, and then the first principal stress is calculated using formula (1). σ 1 and the third principal stress σ 3. Used to analyze the stress distribution during the temperature difference test of cold-bent glass. ， in the formula E For elastic modulus, µ It is Poisson's ratio.

7. The method according to claim 6, wherein the preset arch height is 1.5-2 times the designed arch height, used to verify overload conditions.

8. The method according to claim 6, wherein the graded heating regime divides the target high temperature into at least 8 levels, each level being heated by 5°C and held at that temperature for 5 minutes.

9. The method according to claim 6, wherein the rapid cooling test takes no more than 10 minutes to reduce the temperature from 60°C to 20°C.

10. The method of claim 6, wherein the safety assessment is based on the absence of cracks in the glass and the maximum thermal stress being below the allowable strength as the qualification criteria.

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