A real fire test device and test method for a large-diameter cable test model

Abstract

The present invention discloses a real fire test device and test method for a large-diameter cable test model. The device includes a multidimensional adjustment system, a real fire control system, a temperature monitoring system, a calorimetric and flue gas purification system, high-temperature resistant video recording equipment, a thermal imager, and a large-diameter cable test model. The multidimensional adjustment system includes a column fixed with a guide rail, a crossbeam movable along the guide rail, and a height adjustment system and an angle adjustment system capable of adjusting the height and angle of the large-diameter cable test model. The real fire control system can control the opening of the premixed burner and the fan frequency to control the intensity of the fire source, thereby providing different types of realistic fire scenes for vehicle fires. Before testing the large-diameter cable test model, it is necessary to calibrate the spatial temperature field to determine the spatial position of the large-diameter cable test model. The present invention can provide a solution for testing the fire performance of large-diameter cable test models of bridges in real spatial conditions, and provide technical support for the fire resistance design of large-diameter cable test models for long-span bridges.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge fire resistance testing, and in particular to a real fire testing device and a testing method for a large-diameter cable test model. Background Art

[0002] Cables are the core load-bearing components of long-span bridges, and their performance directly impacts the safety of the bridge structure. Vehicle fires are the primary cause of bridge fires. Vehicles that catch fire are often parked in emergency lanes close to cables. Vehicle fires are characterized by high heat release rates and rapid fire growth, making cables susceptible to high-temperature fire environments. Degradation of the cables' mechanical properties in high-temperature environments can lead to catastrophic consequences. Existing cable fire tests are mostly furnace-temperature tests, where the cables are fixed to brackets inside a furnace. During the test, the cables are exposed to a uniform temperature field. These tests have the following main issues: 1. In furnace-temperature tests, the cable is exposed to fire uniformly on all sides, resulting in a uniform temperature field. In real-world fires, however, only one side of the cable is exposed to fire, resulting in a non-uniform temperature field. 2. Cables have an inclination angle, and cable fire protection measures vary with cable height. Conventional testing methods cannot change the height and inclination of fixed cables, making it difficult to reflect the cable's true spatial state. Summary of the Invention

[0003] The purpose of the present invention is to provide a real fire test device and test method for a large-diameter cable test model. Through a multi-dimensional adjustment system, real fire control technology and high-fidelity model design, the core problems of fire scene distortion, fixed spatial state, and model reduction deviation in traditional furnace temperature tests are solved, which significantly improves the accuracy and practicality of the fire performance test of the large-diameter cable test model, and provides key technical support for the fire resistance optimization design of the large-diameter cable test model for large-span bridges.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a large-diameter cable test model real fire test device, comprising:

[0006] The multi-dimensional adjustment system includes two columns, a beam slidably connected to the columns, a height adjustment system, and an angle adjustment system. The angle adjustment system is located at the bottom of the beam and is connected to the large-diameter cable test model.

[0007] The real fire control system includes a premix burner and a fan that are interconnected. The opening of the premix burner and the frequency of the fan are both regulated by the control cabinet;

[0008] The temperature monitoring system includes a thermocouple tree and a collector, wherein the thermocouple tree and the thermocouples embedded in the large-diameter cable test model are electrically connected to the collector;

[0009] The calorimetric and flue gas purification system includes a smoke hood installed above the column, which is connected to a water circulation purifier through a smoke pipe. A gas analyzer for analyzing the oxygen content in the smoke pipe is installed next to the water circulation purifier;

[0010] It also includes high-temperature resistant video recording equipment and thermal imagers, which are used to record the actual fire and heat transfer process of the fire scene and the large-diameter cable test model in real time.

[0011] Preferably, the large-diameter cable test model comprises:

[0012] A cable test model of a cable strand assembly type has a cross-sectional diameter proportionally reduced from that of a real cable. The cable test model is composed of multiple parallel strands of equal length and aligned ends, secured together by a number of annular steel clamps. The strand reduction ratio is consistent with that of the cable test model. The strands are formed by extruding multiple bundles of fine steel wires into round shapes, and the fine steel wires are staggered and secured at both ends and in the middle with steel ties to reduce the porosity of the cable test model.

[0013] Thermocouples are welded to the measuring point surfaces of several strands inside the cable test model and led out through the gaps between the strands. Steel gaskets are installed on the thermocouple surfaces exposed outside the cable test model to isolate the flame. The strands welded with thermocouples are positioned in sequence within the cable test model according to the target measuring point locations.

[0014] The steel wire is wrapped around the surface of the cable test model to prevent the flame from directly contacting the cable test model.

[0015] Preferably, the minimum value of the diameter of the large-diameter cable test model is within an error tolerance range of 5%, and its diameter is not less than the result determined by the following formula:

[0016]

[0017] Where R0 is the minimum cross-sectional diameter of the large-diameter cable test model, R is the prototype diameter of the large-diameter cable test model, and e is a natural constant, 80mm≤R≤1500mm.

[0018] Preferably, the height adjustment system is provided with two groups, which are respectively arranged at the top of the two columns. The height adjustment system includes an electric lifting device arranged on the non-fire-affected side of the column. The steel wire rope on the electric lifting device passes through several fixed pulleys arranged at the top of the column and is connected to the beam on the same side. A first lifting ring is provided on the top of the beam, and a first hook adapted to the first lifting ring is provided at the end of the steel wire rope. The height of the large-diameter cable test model is adjusted by raising and lowering the beam.

[0019] Preferably, the angle adjustment system is provided with two groups, which are symmetrically arranged along the middle of the beam. The angle adjustment system includes a chain and a second lifting ring connected to the beam. The lower part of the beam is provided with a plurality of bolt holes adapted to the second lifting ring. The lower end of the second lifting ring is connected to the second hook at the upper end of the chain. The second hook at the lower end of the chain is connected to the steel wire rope. The steel wire rope is sleeved between the two annular steel hoops at the end of the large-diameter cable test model. The inclination angle of the large-diameter cable test model is adjusted by adjusting the relative length of the two chains. A fireproof protective layer is provided on the beam and the angle adjustment system.

[0020] Preferably, the thermocouple tree is arranged above and around the premix burner to accurately measure the fire environment temperature where the large diameter cable test model is located, and the collector synchronously collects temperature data of the space and the large diameter cable test model.

[0021] Preferably, the column is provided with an upper limiter and a lower limiter in its vertical direction, the lower limiter is slidably connected to the column and can be fixed by bolts, the lower limiter and the column are provided with threaded holes adapted to the bolts, and the lower limiter can ensure that the large-diameter cable test model does not contact the ground when the beam descends to the restricted position.

[0022] The present invention also provides a test method for a large-diameter cable test model real fire test device, comprising the following steps:

[0023] S1: Conduct numerical simulations of large-diameter cable test models for fire, summarize the most unfavorable fire scenarios, and determine the design temperature of large-diameter cable test models under real-world conditions;

[0024] S2: Make a large-diameter cable test model and determine its location during the test. Use the multi-dimensional adjustment system to adjust the crossbeam height to the specified position in advance.

[0025] S3: Arrange thermocouple trees, thermal imagers, and high-temperature video equipment at designated locations in the test area;

[0026] S4: According to the layout requirements of the real fire control system, move the premix burner to the lower part of the planned location of the large-diameter cable test model. Connect the premix burner and the fan through the air duct. Connect the premix burner to the gas source through the gas pipeline. Connect the control cabinet to the premix burner through the wire. Provide fire protection for the wire, air duct and gas pipeline.

[0027] S5: Turn on the fan and gas source, control the fan frequency and premix burner opening through the control cabinet and ignite, and record the space temperature field through the data acquisition instrument;

[0028] S6: Adjust the fan frequency and premix burner opening multiple times, record the spatial temperature field respectively, and determine the height, fan frequency and premix burner opening of the large-diameter cable test model based on the fortification temperature of the large-diameter cable test model obtained by simulation;

[0029] S7: Move the large-diameter cable test model to the bottom of the beam, connect the first hook to the first lifting ring, use the multi-dimensional adjustment system to adjust the height and vertical inclination of the large-diameter cable test model, complete the positioning of the large-diameter cable test model, and connect the thermocouples arranged inside and outside the large-diameter cable test model to the data collector respectively;

[0030] S8: Start the calorimetric and flue gas purification system;

[0031] S9: Open the fan and gas pipeline, adjust the fan frequency and the opening of the premix burner to the target value through the control cabinet, ignite and start the test;

[0032] S10: After the test, the temperature field of the large-diameter cable test model monitored by the collector is obtained. According to the surface temperature of the steel wire and the fire resistance time on the large-diameter cable test model, it is determined whether the fire protection structure meets the fire resistance requirements. Real fire tests are carried out on large-diameter cable test models with different fire protection structures to explore the influence of different structures on the fire resistance performance of large-diameter cable test models.

[0033] Preferably, spatial temperature field calibration is required before the fire test to obtain the spatial temperature field above the premixed burner, and the position of the large-diameter cable test model is determined according to the required target temperature and spatial temperature field of the large-diameter cable test model.

[0034] Preferably, after the test, the flue gas composition is detected by a gas analyzer to obtain the heat release rate of the test process, and the harmful gases are treated using a water circulation purifier to ensure that the emissions meet environmental protection requirements.

[0035] The beneficial effects of the present invention are:

[0036] 1. The fire source intensity is dynamically adjusted through the premix burner, fan, and control cabinet to simulate the real fire scene of different vehicle fires, such as heat release rate and flame distribution. In combination with the temperature monitoring system thermocouple tree + thermal imager, the spatial temperature field calibration and control are realized, significantly improving the realism of the test scene.

[0037] 2. The height and angle adjustment methods allow for flexible adjustment of the height, inclination, and horizontal position of the large-diameter cable test model to accommodate the actual spatial state of the large-diameter cable test model for bridges, such as the curved shape of the large-diameter cable test model for suspension bridges, providing data support for fire resistance design in different scenarios.

[0038] 3. The model diameter can be designed to be over 500mm as needed. The proportional reduction design ensures that the porosity is close to that of the actual large-diameter cable test model. The parallel arrangement of multiple cable strands and the steel wire extrusion process are used to accurately simulate the heat transfer path and structural characteristics of the large-diameter cable test model of an actual bridge.

[0039] 4. Pre-embedded thermocouple technology: Steel gaskets are installed on the surface of the thermocouple outside the cable to reduce thermal convection interference and ensure the accuracy of temperature data.

[0040] 5. The calorimetric and flue gas purification system and gas analyzer process harmful flue gases in real time to avoid pollution of the test environment; the height adjustment system is away from the fire side to reduce the risk of equipment damage due to heat;

[0041] 6. The most unfavorable scenario is predicted through numerical fire simulation, and the location of the large-diameter cable test model is determined in combination with spatial temperature field calibration to achieve scientific optimization of the test plan. It supports repeated tests under multiple working conditions to adjust the fire source intensity and the location of the large-diameter cable test model, etc., and can systematically evaluate the fire resistance limit of different fire-proof structures, providing a comprehensive technical basis for the fire-resistant design of large-diameter cable test models for long-span bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic structural diagram of a real fire test device for a large-diameter cable test model provided by an embodiment of the present invention;

[0044] Figure 2 A schematic structural diagram of a multi-dimensional adjustment system provided in an embodiment of the present invention;

[0045] Figure 3 A schematic structural diagram of a column provided in an embodiment of the present invention;

[0046] Figure 4 A schematic structural diagram of a calorimetric and flue gas purification system provided in an embodiment of the present invention;

[0047] Figure 5 A schematic structural diagram of a real fire control system provided by an embodiment of the present invention;

[0048] Figure 6 A schematic diagram of the structure of a temperature monitoring system provided by an embodiment of the present invention;

[0049] Figure 7A schematic structural diagram of a large-diameter cable test model provided by an embodiment of the present invention;

[0050] Figure 8 A schematic cross-sectional view of a large-diameter cable test model provided by an embodiment of the present invention;

[0051] Figure 9 A schematic structural diagram of an angle adjustment system provided in an embodiment of the present invention.

[0052] Explanation of reference numerals: 1-multi-dimensional adjustment system; 11-column; 12-crossbeam; 121-first lifting ring; 13-guide rail; 14-height adjustment system; 141-electric lifting equipment; 142-fixed pulley; 143-wire rope; 144-first hook; 15-upper limiter; 16-lower limiter; 17-angle adjustment system; 171-second lifting ring; 172-chain; 173-second hook; 174-steel strand; 2-real fire control system; 21-premixed Burner; 22-Fan; 23-Control cabinet; 24-Air duct; 25-Gas pipeline; 26-Wire; 3-Temperature monitoring system; 31-Thermocouple tree; 32-Collector; 4-Calorific and flue gas purification system; 41-Fume hood; 42-Gas analyzer; 43-Water circulation purifier; 44-Fume duct; 5-High-temperature resistant video equipment; 6-Thermal imager; 7-Large diameter cable test model; 71-Cable strand; 72-Annular steel clamp; 73-Steel wire; 74-Thermocouple. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] like Figures 1 to 9 As shown, a large diameter cable test model real fire test device includes:

[0055] The multi-dimensional adjustment system 1 includes two columns 11, a beam 12 adapted to the guide rails 13 on the columns 11 and capable of moving up and down, a height adjustment system 14 for adjusting the height of the beam 12, and an angle adjustment system 17 for adjusting the inclination angle of the large-diameter cable test model 7; the angle adjustment system 17 is provided at the bottom of the beam 12 and connected to the large-diameter cable test model 7;

[0056] The height adjustment system 14 comprises two groups, one mounted on top of each column 11. The system 14 includes an electric lifting device 141 on the non-fire-affected side of the column 11. A steel wire rope 143 on the electric lifting device 141 passes through several fixed pulleys 142 mounted on top of the column 11 before connecting to the crossbeam 12 on the same side. A first lifting ring 121 is provided at the top of the crossbeam 12, and a first hook 144 is provided at the end of the steel wire rope 143, which mates with the first lifting ring 121.

[0057] The angle adjustment system 17 is provided with two groups, which are symmetrically arranged along the middle of the beam 12 and are located on the non-fire-exposed side. The angle adjustment system 17 includes a chain 172 and a second lifting ring 171 connected to the beam 12. The lower part of the beam 12 is provided with a plurality of bolt holes adapted to the second lifting ring 171. The lower end of the second lifting ring 171 is connected to the second hook 173 at the upper end of the chain 172. The second hook 173 at the lower end of the chain 172 is connected to the steel strand 174. The steel strand 174 is sleeved between the two annular steel clamps 72 at the end of the large-diameter cable test model 7. The inclination angle of the large-diameter cable test model 7 is adjusted by adjusting the relative length of the two chains 172. The beam 12 and the angle adjustment system 17 are both provided with a fireproof protective layer to ensure the safety of the system during the test.

[0058] The column 11 is provided with an upper limiter 15 and a lower limiter 16 in its vertical direction to prevent the beam 12 from detaching from the guide rail 13 during the lifting process. The lower limiter 16 is slidably connected to the guide rail on the column 11 and can be fixed by bolts. The lower limiter 16 and the column 11 are provided with threaded holes adapted to the bolts. The position of the lower limiter 16 can ensure that the large-diameter cable test model 7 does not touch the ground when the beam 12 descends to the restricted position.

[0059] The thermocouple tree 31 is arranged above and around the premix burner 21 to accurately measure the fire environment temperature of the large diameter cable test model 7. The collector 32 synchronously collects temperature data of the space and the large diameter cable test model 7.

[0060] The real fire control system 2 includes a premix burner 21 and a fan 22, each electrically connected to a control cabinet 23. The premix burner 21 is connected to the fan 22 via an air duct 24. The control cabinet 23 is used to adjust the opening of the premix burner 21 and the frequency of the fan 22 to simulate the vehicle fire source;

[0061] The temperature monitoring system 3 includes a thermocouple tree 31 for monitoring the spatial temperature field and a data collector 32 for recording temperature data. The thermocouple tree 31 and the thermocouple 74 embedded in the large-diameter cable test model 7 are electrically connected to the data collector 32.

[0062] The calorimetric and flue gas purification system 4 includes a smoke hood 41 located above the column 11. The smoke hood 41 is connected to a water circulation purifier 43 via a smoke pipe 44. A gas analyzer 42 is provided next to the water circulation purifier 43 for analyzing the oxygen content in the smoke pipe 44 and thereby measuring the test heat release rate.

[0063] High-temperature resistant video recording equipment 5 and thermal imager 6 are used to record the actual fire and heat transfer process of the fire scene and the large-diameter cable test model 7 in real time;

[0064] The large diameter cable test model 7 comprises:

[0065] The cable test model is a cable-strand assembly model with a cross-sectional diameter proportionally reduced from that of a real cable. The cable test model is composed of multiple parallel strands 71 ​​of equal length and aligned at both ends, secured by a number of annular steel clamps 72. The strands 71 ​​are reduced in scale to match that of the cable test model. The strands 71 ​​are formed by extruding multiple bundles of fine steel wire into round shapes, and the fine steel wires are staggered and secured at both ends and in the middle with steel ties to reduce the porosity of the cable test model.

[0066] Thermocouples 74 are welded to the measuring point surfaces of several strands 71 ​​within the cable test model and lead out through the gaps between the strands 71. Steel gaskets are installed on the surfaces of the thermocouples 74 exposed outside the cable test model to isolate the flame. The strands 71 ​​welded with thermocouples 74 are positioned in sequence within the cable test model according to the target measuring point locations.

[0067] The steel wire 73 is wound around the surface of the cable test model to prevent the flame from directly contacting the cable test model.

[0068] The minimum diameter of the large diameter cable test model is within the allowable error range of 5%, and its diameter is not less than the result determined by the following formula;

[0069]

[0070] Where R0 is the minimum cross-sectional diameter of the large-diameter cable test model, R is the prototype diameter of the large-diameter cable test model, and e is a natural constant, 80mm≤R≤1500mm.

[0071] The present invention also provides a test method for a large-diameter cable test model real fire test device, comprising the following steps:

[0072] S1: Conduct numerical simulations of large-diameter cable test models for fire, summarize the most unfavorable fire scenarios, and determine the design temperature of large-diameter cable test models under real-world conditions;

[0073] S2: Make a large-diameter cable test model 7 and determine its location during the test. Use the multi-dimensional adjustment system 1 to adjust the height of the crossbeam 12 to the specified position in advance.

[0074] S3: Arrange the thermocouple tree 31, thermal imager 6 and high temperature resistant video recording device 5 at designated locations in the test area;

[0075] S4: According to the layout requirements of the real fire control system 2, move the premix burner 21 to the lower part of the planned location of the large-diameter cable test model 7, connect the premix burner 21, the air duct 24, and the fan 22, connect the premix burner 21 to the gas source through the gas pipeline 25, connect the control cabinet 23 to the premix burner 21 through the wire 26, and provide fire protection for the wire 26, the air duct 24, and the gas pipeline 25;

[0076] S5: Turn on the fan 22 and the gas source, control the frequency of the fan 22 and the opening of the premix burner 21 through the control cabinet 23 and ignite, and record the space temperature field through the data acquisition instrument 32;

[0077] S6: Adjust the frequency of the fan 22 and the opening of the premix burner 21 multiple times, record the spatial temperature field respectively, and determine the height of the large-diameter cable test model 7, the frequency of the fan 22, and the opening of the premix burner 21 according to the fortification temperature of the large-diameter cable test model 7 obtained by simulation;

[0078] S7: Move the large-diameter cable test model 7 to below the crossbeam 12, connect the first hook 144 to the first lifting ring 121, use the multi-dimensional adjustment system 1 to adjust the height and vertical inclination of the large-diameter cable test model 7, complete the positioning of the large-diameter cable test model 7, and connect the thermocouples 74 arranged inside and outside the large-diameter cable test model 7 to the data collector 32;

[0079] S8: Start the calorimetric and flue gas purification system 4;

[0080] S9: Turn on the fan 22 and the gas pipeline 25, adjust the fan frequency and the premix burner opening to the target values ​​through the control cabinet, ignite and start the test;

[0081] S10: After the test, the temperature field of the large-diameter cable test model 7 monitored by the collector 32 is obtained, and whether the fireproof structure meets the fire resistance requirements is determined based on the surface temperature of the steel wire of the large-diameter cable test model 7 and the fire resistance time. Real fire tests of the large-diameter cable test model 7 with different fireproof structures are carried out to explore the influence of different structures on the fire resistance performance of the large-diameter cable test model 7.

[0082] Before the fire test, the spatial temperature field calibration is required to obtain the spatial temperature field above the premixed burner 21, and the position of the large diameter cable test model 7 is determined according to the target temperature and spatial temperature field of the large diameter cable test model 7 as required.

[0083] After the test, the smoke composition is detected by a gas analyzer 42, and the harmful gases are treated by a water circulation purifier 43 to ensure that the emissions meet environmental protection requirements.

[0084] This method solves the core problems of traditional furnace temperature tests, such as fire scene distortion, fixed spatial state, and model reduction deviation, through a multi-dimensional adjustment system 1, real fire control technology, and high-fidelity model design. It significantly improves the accuracy and practicality of the fire performance test of the large-diameter cable test model 7, and provides key technical support for the fire-resistant optimization design of the large-diameter cable test model 7 for large-span bridges.

[0085] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A large diameter cable test model real fire test device, characterized in that: include: A multi-dimensional adjustment system (1) includes two columns (11), a crossbeam (12) slidably connected to the columns (11), a height adjustment system (14), and an angle adjustment system (17); the angle adjustment system (17) is arranged at the bottom of the crossbeam (12) and connected to a large-diameter cable test model (7); A true fire control system (2) includes a premix burner (21) and a fan (22) that are interconnected, wherein the opening of the premix burner (21) and the frequency of the fan (22) are both regulated by a control cabinet (23); A temperature monitoring system (3) includes a thermocouple tree (31) and a collector (32), wherein the thermocouple tree (31) and a thermocouple (74) embedded in the large-diameter cable test model (7) are electrically connected to the collector (32); The calorimetric and flue gas purification system (4) includes a smoke collecting hood (41) disposed above the column (11), the smoke collecting hood (41) being connected to a water circulation purifier (43) via a smoke pipe (44), and a gas analyzer (42) for analyzing the oxygen content in the smoke pipe (44) being disposed next to the water circulation purifier (43); It also includes high temperature resistant video recording equipment (5) and thermal imager (6) for real-time recording of the fire scene and the actual fire and heat transfer process of the large diameter cable test model (7); The large diameter cable test model (7) comprises: A cable test model of a cable strand assembly type, wherein the cross-sectional diameter is proportionally reduced according to that of a real cable, wherein the cable test model is composed of a plurality of parallel cable strands (71) of the same length and aligned at both ends, which are locked and fixed by a plurality of annular steel clamps (72); the reduction ratio of the cable strands (71) is consistent with the reduction ratio of the cable test model, and the cable strands (71) are formed by extruding a plurality of bundles of thin steel wires into a circle and the thin steel wires are staggered and fixed at both ends and the middle position by steel tie bands to reduce the porosity of the cable test model; Thermocouples (74) are welded to the measuring point surfaces of a plurality of strands (71) inside the cable test model and are led out through the gaps between the strands (71). Steel gaskets are installed on the surfaces of the thermocouples (74) exposed outside the cable test model to isolate the flame. The strands (71) welded with thermocouples (74) are positioned in sequence within the cable test model according to the target measuring point positions. A steel wire (73) is wound around the surface of the cable test model to prevent the flame from directly contacting the cable test model; The diameter of the large-diameter cable test model (7) can be up to 1500mm as required. The porosity is ensured to be close to that of the real large-diameter cable test model through proportional reduction design. In addition, the parallel arrangement of multiple cable strands and the steel wire extrusion process are used to accurately simulate the heat transfer path and structural characteristics of the large-diameter cable test model of the actual bridge. The height adjustment system (14) is provided with two groups, which are respectively provided at the tops of the two columns (11). The height adjustment system (14) includes an electric lifting device (141) provided at the non-fire side of the column (11). The steel wire rope (143) on the electric lifting device (141) passes through a plurality of fixed pulleys (142) provided at the top of the column (11) and is connected to the beam (12) on the same side. The top of the beam (12) is provided with a first lifting ring (121). The end of the steel wire rope (143) is provided with a first hook (144) adapted to the first lifting ring (121). The height of the large-diameter cable test model (7) is adjusted by raising and lowering the beam (12). The angle adjustment system (17) is provided with two groups, which are symmetrically arranged along the middle of the beam (12). The angle adjustment system (17) includes a chain (172) and a second lifting ring (171) connected to the beam (12). The lower part of the beam (12) is provided with a plurality of bolt holes adapted to the second lifting ring (171). The lower end of the second lifting ring (171) is connected to the second hook (173) at the upper end of the chain (172). The second hook (173) at the lower end of the chain (172) is connected to the steel strand (174). The steel strand (174) is sleeved between two annular steel hoops (72) at the ends of the large-diameter cable test model (7). The inclination angle of the large-diameter cable test model (7) is adjusted by adjusting the relative length of the two chains (172). The beam (12) and the angle adjustment system (17) are both provided with a fireproof protective layer.

2. A large diameter cable test model real fire test device according to claim 1, characterized in that: The thermocouple tree (31) is arranged above and around the premix burner (21) to accurately measure the temperature of the fire environment where the large-diameter cable test model (7) is located. The collector (32) synchronously collects temperature data of the space and the large-diameter cable test model (7).

3. A large diameter cable test model real fire test device as claimed in claim 2, characterized in that: The column (11) is provided with an upper limiter (15) and a lower limiter (16) in its vertical direction. The lower limiter (16) is slidably connected to the column (11) and can be fixed by bolts. The lower limiter (16) and the column (11) are provided with threaded holes adapted to the bolts. The lower limiter (16) can ensure that the large-diameter cable test model (7) does not touch the ground when the crossbeam (12) descends to the restricted position.

4. A test method for a large diameter cable test model real fire test device according to claim 3, characterized in that: The following steps are involved: S1: Conduct numerical simulation of fire on the large-diameter cable test model (7), summarize the most unfavorable fire scenario, and determine the design temperature of the large-diameter cable test model (7) under real environment; S2: Make a large-diameter cable test model (7) and determine its location during the test, and adjust the height of the crossbeam (12) to the specified position in advance through the multi-dimensional adjustment system (1); S3: Arrange the thermocouple tree (31), thermal imager (6) and high temperature resistant video recording equipment (5) at designated locations in the test area; S4: According to the layout requirements of the real fire control system (2), the premix burner (21) is moved to the lower part of the proposed position of the large diameter cable test model (7), the premix burner (21) and the fan (22) are connected through the air duct (24), the premix burner (21) is connected to the gas source through the gas pipeline (25), the control cabinet (23) is connected to the premix burner (21) through the wire (26), and the wire (26), the air duct (24) and the gas pipeline (25) are fire-proofed; S5: Turn on the fan (22) and the gas source, control the fan (22) frequency and the premix burner (21) opening through the control cabinet (23) and ignite, and record the spatial temperature field through the acquisition instrument (32); dynamically adjust the fire source intensity through the premix burner (21), the fan (22) and the control cabinet (23), simulate the real fire scene of different vehicle fires, including heat release rate and flame distribution, and combine the temperature monitoring system thermocouple tree + thermal imager to realize the calibration and control of the spatial temperature field, significantly improving the fidelity of the test scene; S6: Before the fire test, it is necessary to calibrate the space temperature field to obtain the space temperature field above the premix burner (21). By adjusting the frequency of the fan (22) and the opening of the premix burner (21) multiple times, the space temperature field is recorded respectively. According to the fortification temperature of the large-diameter cable test model (7) obtained by simulation, the height of the large-diameter cable test model (7), the frequency of the fan (22) and the opening of the premix burner (21) are determined; S7: Move the large-diameter cable test model (7) to the bottom of the beam (12), connect the first hook (144) to the first hanging ring (121), and use the multi-dimensional adjustment system (1) to adjust the height and vertical inclination of the large-diameter cable test model (7). Use the multi-dimensional adjustment system (1) to flexibly adjust the height, inclination and horizontal position of the large-diameter cable test model to adapt to the real spatial state of the large-diameter cable test model (7) of the bridge; The large-diameter cable test model (7) is positioned, and the thermocouples (74) arranged inside and outside the large-diameter cable test model (7) are connected to the collector (32) respectively; S8: Start the calorimetric and flue gas purification system (4); S9: Turn on the fan (22) and the gas pipeline (25), adjust the frequency of the fan (22) and the opening of the premix burner (21) to the target values ​​through the control cabinet (23), ignite and start the test; S10: After the test, the temperature field of the large-diameter cable test model (7) monitored by the collector (32) is obtained, and whether the fireproof structure meets the fire resistance requirements is determined based on the surface temperature of the steel wire (73) on the large-diameter cable test model (7) and the fire resistance time. Real fire tests are carried out on the large-diameter cable test model (7) with different fireproof structures to explore the influence of different structures on the fire resistance performance of the large-diameter cable test model (7).

5. The test method of a large diameter cable test model real fire test device according to claim 4, characterized in that: After the test, the smoke composition is detected by a gas analyzer (42) to obtain the heat release rate during the test process, and the harmful gases are treated by a water circulation purifier (43) to ensure that the emissions meet environmental protection requirements.

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