Steel structure temperature rising performance determination method and terminal

Abstract

The application provides a steel structure temperature rise performance determination method and a terminal, including: obtaining the thickness and type of a protective layer of a target steel structure, and a preset power fire temperature rise curve function; the power fire temperature rise curve function is obtained by fitting power facility fire experiment data; obtaining the equivalent thermal resistance of the protective layer according to the type and thickness of the protective layer; obtaining a target type temperature rise calculation formula corresponding to the type of the protective layer; substituting the equivalent thermal resistance and the power fire temperature rise curve function into the target type temperature rise calculation formula to obtain the core temperature of the target steel structure under different preset fire times; and evaluating the temperature rise performance of the target steel structure according to the core temperature. Thus, the core temperature under different preset fire times can accurately describe the temperature rise curve of the target steel structure, and the temperature rise performance of the target steel structure under power fire is determined.

Description

Technical Field

[0001] This invention relates to the field of fire protection technology for steel structures, and in particular to a method and terminal for determining the temperature rise performance of steel structures. Background Technology

[0002] In related technologies, for steel components protected by fire-retardant coatings, the temperature rise performance under fire conditions needs to be calculated or evaluated in building fire protection design to determine whether they can meet the design fire resistance limit requirements. However, the fire scenarios based on existing methods do not match the actual fire characteristics of power facility sites. Furthermore, existing steel structure fire protection designs typically design fire resistance limits based on the fire resistance rating and fire hazard category of substation buildings, resulting in a rather coarse design that only provides a discrete fire resistance limit time value. Therefore, it is difficult to accurately determine the temperature rise performance of protected steel components under power fire conditions. Summary of the Invention

[0003] The technical problem to be solved by this invention is: how to accurately evaluate the temperature rise performance of protected steel components under electrical fire conditions.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for determining the temperature rise performance of steel structures includes: The thickness and type of the protective layer of the target steel structure are obtained, as well as a preset electrical fire temperature rise curve function; the electrical fire temperature rise curve function is obtained by fitting experimental data of electrical facility fires. The equivalent thermal resistance of the protective layer is obtained based on its type and thickness. Obtain the target type temperature rise calculation formula corresponding to the type of the protective layer; Substituting the equivalent thermal resistance and the electric fire temperature rise curve function into the target type temperature rise calculation formula, the core temperature of the target steel structure under different preset fire exposure times is obtained. The heating performance of the target steel structure is evaluated based on the core temperature.

[0005] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows: A terminal for determining the temperature rise performance of a steel structure includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the method for determining the temperature rise performance of a steel structure as described above.

[0006] The beneficial effects of this invention are as follows: by fitting experimental data of power facility fires to obtain the temperature rise curve function of power fires, it is possible to effectively simulate the temperature change of the target steel structure under power fire scenarios; then, based on the type and thickness of the protective layer of the target steel structure, the equivalent thermal resistance and the target type temperature rise calculation formula are obtained, which can further combine the material properties of the target steel structure to obtain the core temperature of the target steel structure under different preset fire exposure times. Thus, based on the core temperature under different preset fire exposure times, the temperature rise curve of the target steel structure can be accurately described, thereby determining the temperature rise performance of the target steel structure under power fires. Attached Figure Description

[0007] Figure 1 This is a flowchart of a method for determining the heating performance of a steel structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-section of a typical test steel component and a schematic diagram of the arrangement of thermocouple measuring points in this embodiment; Figure 3 A comparison chart of temperature rise curves for different types of fires; Figure 4 This is a schematic diagram of a terminal for determining the heating performance of a steel structure according to an embodiment of the present invention. Detailed Implementation

[0008] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0009] In existing technologies, the fire scenarios used to calculate or evaluate the temperature rise performance of steel components do not match the actual fire characteristics of power facility locations. For example, current standards are mainly based on the temperature rise curves of fibrous fires (such as the ISO-834 standard curve) or hydrocarbon fires, while fires in power facility locations (such as substations) mainly originate from electrical equipment failures, transformer oil leaks, and other factors, and their combustibles are primarily organic polymer materials. The temperature rise rate of such fires is extremely rapid, reaching approximately 1000°C within 15 minutes, far exceeding the temperature rise rate of fibrous fires in ordinary buildings. Meanwhile, existing fire protection designs for steel structures are mainly based on the "Code for Fire Protection Design of Buildings," the "Code for Fire Protection Design of Thermal Power Plants and Substations," and the "Technical Code for Fire Protection of Steel Structures." These methods determine the fire resistance limit based on the fire resistance rating and fire hazard category of the substation building. However, these methods only provide a discrete fire resistance limit time value, making it difficult to precisely describe the real-time temperature changes of steel components throughout the entire fire exposure process. Therefore, they cannot provide engineers with more detailed temperature rise data to assess the thermal response of the structure under real electrical fire conditions. Furthermore, in the specific scenario of an electrical fire, due to the extremely rapid temperature rise rate and extremely high ambient temperature, fire-resistant protective materials (especially intumescent fire-retardant coatings) may experience failure behaviors such as detachment and cracking of the foam layer at high temperatures, leading to dynamic changes in their thermal insulation performance. Therefore, existing methods are insufficient to accurately assess the temperature rise performance of protected steel components under electrical fire conditions.

[0010] To address at least the aforementioned issues, a temperature rise curve function for power facility fires was obtained by fitting experimental data. Then, based on the type and thickness of the protective layer of the target steel structure, an equivalent thermal resistance and a temperature rise calculation formula for the target type were derived. Substituting the equivalent thermal resistance and the power facility fire temperature rise curve function into the target type temperature rise calculation formula yielded a core temperature function used to analyze the temperature rise curve of the target steel structure. This method effectively simulates the temperature changes of the target steel structure under power facility fire scenarios, thereby determining the temperature rise performance of the target steel structure under power facility fire conditions.

[0011] The following describes in detail a method for determining the temperature rise performance of steel structures according to the present invention. Please refer to [link / reference]. Figure 1 The method 100 includes steps 101 to 105: Step 101: Obtain the thickness and type of the protective layer of the target steel structure, as well as the preset electrical fire temperature rise curve function; the electrical fire temperature rise curve function is obtained by fitting electrical facility fire experimental data. The steel component is preferably hot-rolled H-beam or hot-rolled I-beam, and is exposed to fire on three sides. The protective layer thickness δ refers to the average dry film thickness of the fire-resistant protective material coated or covered on the surface of the steel component, in millimeters (mm). In practical engineering applications, the protective layer thickness δ is determined by the designer based on the design fire resistance limit requirements of the steel component, the type of fire-resistant protective material used, and the product technical specifications. In the experimental verification of this embodiment, the measurement method of the protective layer thickness δ can be carried out in accordance with the relevant provisions of "Fire-resistant Coatings for Steel Structures" (GB14907-2018). Specifically, the coating thickness should be measured on each fire-exposed surface of the specimen, with no less than two measurement sections per meter along the length of the specimen. At each measurement section, measurement points can be set at the midpoints of both sides of the web, the midpoints of both sides of the lower surface of the upper flange, the midpoints of both sides of the upper surface of the lower flange, and the midpoint of the lower surface of the lower flange. The average value after removing the maximum and minimum values ​​is taken as the coating thickness. For intumescent fire-retardant coatings, the coating thickness is accurate to 0.1 mm; for non-intumescent fire-retardant coatings, the coating thickness is accurate to 1 mm. The above coating thickness includes the total thickness of the anti-rust paint, anti-rust liquid, topcoat, and reinforcement measures.

[0012] Step 102: Obtain the equivalent thermal resistance of the protective layer based on its type and thickness; wherein, the equivalent thermal resistance... It is a physical quantity that comprehensively reflects the thickness of the protective layer and the thermal insulation performance of the material, and its unit is Kelvin per watt (m²). 2 ·K / W).

[0013] Step 103: Obtain the target type temperature rise calculation formula corresponding to the type of the protective layer; wherein, the protective layer includes different types such as non-intumescent fire retardant coating and intumescent fire retardant coating, and different target type temperature rise calculation formulas are set according to different types.

[0014] Step 104: Substitute the equivalent thermal resistance and the electric fire temperature rise curve function into the target type temperature rise calculation formula to obtain the core temperature of the target steel structure under different preset fire exposure times; that is, obtain the core temperature change function with time as the independent variable and temperature rise as the dependent variable.

[0015] Step 105: Evaluate the heating performance of the target steel structure based on the core temperature.

[0016] As described above, the beneficial effects of this invention are as follows: by fitting experimental data of power facility fires to obtain the temperature rise curve function of power fires, it is possible to effectively simulate the temperature change of the target steel structure under power fire scenarios; furthermore, based on the type and thickness of the protective layer of the target steel structure, the equivalent thermal resistance and the target type temperature rise calculation formula are obtained, which can be further combined with the material properties of the target steel structure to obtain the core temperature of the target steel structure under different preset fire exposure times. Thus, based on the core temperature under different preset fire exposure times, the temperature rise curve of the target steel structure can be accurately described, thereby determining the temperature rise performance of the target steel structure under power fires.

[0017] In one embodiment of the present invention, step 102 includes: obtaining the equivalent thermal conductivity coefficient of the protective layer according to the type and thickness of the protective layer, for example using... The equivalent thermal resistance of the protective layer is obtained based on its thickness and the equivalent thermal conductivity, for example, using parameters. This indicates that, according to the basic principles of heat transfer, for a homogeneous single-layer protective layer, its equivalent thermal resistance is... The calculation formula is: ; The formula is multiplied by 103 because the protective layer thickness δ is in millimeters (mm), and The unit of length in W / (m·K) is meter (m), and millimeters need to be converted to meters to unify the dimensions.

[0018] Among them, the equivalent thermal conductivity coefficient This is a key thermal parameter describing the comprehensive thermal insulation performance of fire-resistant protective materials under specific fire conditions, measured in watts per meter per Kelvin (W / (m·K)). This parameter differs from the inherent thermal conductivity of the material at room temperature; rather, it is an equivalent value under specific fire heating scenarios, taking into account factors such as material heat transfer, possible physicochemical changes (e.g., foaming, dehydration, decomposition), and interfacial thermal resistance with the steel substrate.

[0019] This embodiment uses the equivalent thermal conductivity obtained from a pre-conducted full-size steel component fire resistance test. Recommended values ​​were used to determine this parameter. These tests were conducted on different types of fire-resistant materials under ISO-834 standard temperature rise profiles or hydrocarbon (HC) fire temperature rise profiles, and a system was established through data analysis and reverse calibration. The correspondence between the protective layer type, thickness, and design fire resistance limit. Although the calibration test did not directly use the temperature rise curve of an electrical fire, the HC curve, as a hydrocarbon fire curve with a higher temperature and faster temperature rise, has important reference value for the application of electrical fire temperature rise curve scenarios and can be used as a conservative engineering approximation.

[0020] The equivalent thermal conductivity is explained in detail below. The calibration process and recommended values.

[0021] (I) Overview of Calibration Test Equivalent thermal conductivity The recommended values ​​were derived from tests conducted by the National Fireproof Building Materials Quality Inspection and Testing Center. The test subjects covered typical fire-resistant materials such as non-intumescent fire-retardant coatings (including multiple models such as FP-1, FP-2, FP-3, FP-4, FP-5, FP-6, FP-7, FP-8, FP-9, FP-10, FP-11, FP-12, FP-13, and FP-14), intumescent fire-retardant coatings (including multiple models such as P-1, P-2, P-3, P-4, P-5, P-6, P-7, P-8, P-9, P-10, P-11, P-12, P-13, and P-14), and fireproof boards (such as the 38mm thick calcium silicate board / vermiculite board of model B-1).

[0022] The substrate for the test specimens was HN400×200 hot-rolled H-beams (section modulus of 161 m⁻¹) as specified in GB / T 11263 or I36b hot-rolled I-beams (section modulus of 126 m⁻¹) as specified in GB / T 706. Thermocouples were installed in accordance with the relevant provisions of GB / T 9978.6.

[0023] The experimental temperature rise curves covered the ISO-834 standard temperature rise curves and the HC hydrocarbon fire temperature rise curves. Based on these experiments, a total of 42 sets of valid experimental data were obtained. The expression for the fire temperature rise stage of the HC hydrocarbon fire temperature rise curve is as follows: ; During the experiment, the temperature-time variation data of the thermocouple measuring points embedded on the steel component and the deformation-time variation data of the steel component were measured and recorded.

[0024] Please refer to Figure 2 The test steel member uses an H-section, including the upper flange, lower flange, and web. The placement of thermocouples should be determined based on the fire condition of the steel member. For beam members exposed to fire on three sides (with the upper surface of the upper flange being the opposite side of the fire-exposed surface), thermocouples can be placed at key locations such as the middle of both sides of the web, both sides of the lower surface of the upper flange, both sides of the upper surface of the lower flange, and the lower surface of the lower flange. These measuring points can comprehensively reflect the temperature distribution of the steel member's cross-section.

[0025] (ii) Test equipment The fire resistance test furnace used for the calibration test is the ZY 6248A horizontal and vertical fire resistance test furnace. Its technical indicators meet the test requirements of Chapters 5 and 6 of GB / T 9978.1 "Fire Resistance Test Methods for Building Components - Part 1: General Requirements", and its heating capacity meets the requirements of XF / T 714 "Rapid Heating Fire Resistance Test Method for Fire-Protective Materials for Components".

[0026] The main technical parameters of this refractory testing furnace include: a test temperature of up to 1600℃; an accuracy of ±15℃ for temperature measurement inside the furnace; an accuracy of ±2.5℃ for measuring ambient and unexposed surface temperatures; and a furnace pressure measurement range of 0~100 Pa, measured using a differential pressure gauge. The furnace body adopts a five-layer structure design, with the outer layer at room temperature when the test temperature is 1300℃.

[0027] To adapt to the simulation requirements of various types of heating curves, the refractory test furnace has embedded preset programs for multiple curves into its control system, established a curve parameter database, and achieved seamless switching between different heating curves through optimized control algorithms. This ensures that precise heating control can be achieved when simulating different scenarios such as ISO-834 standard curves, HC hydrocarbon curves, and electric fire heating curves.

[0028] (III) Equivalent thermal conductivity calibration method Equivalent thermal conductivity The calibration employs a combination of data fitting and inverse calculation. Its basic principle is as follows: Given the physical properties of the steel component (density ρ = 7850 kg / m³) 3 Under the premise of specific heat capacity c = 0.6 kJ / (kg·K) and section modulus V / A = 0.05 m, for a certain set of measured protective layer thickness δ and temperature-time test data... The test specimen, assuming a Using the initial values ​​and substituting them into the simplified heating calculation formula, the theoretical temperature curve is obtained. Then, the least squares method is used to make and Minimize the root mean square error between the two samples to determine the optimal value for that sample. Value. After performing the above calibration operation on multiple groups of specimens of the same type but different thicknesses, the value of this type of fireproof protective material can be obtained. Statistical correlation between thickness and design fire resistance limit.

[0029] (iv) Non-intumescent fire-retardant coatings Recommended value For non-intumescent fire-retardant coatings, the above calibration method was used to obtain the test data of fire-retardant coatings of models FP-1, FP-2, FP-3, FP-4, FP-5, FP-6, FP-7, FP-8, FP-9, FP-10, FP-11, FP-12, FP-13, and FP-14. The relationship between the design fire resistance limit and the coating thickness is shown in Table 1 below: Table 1 Equivalent thermal conductivity coefficient of non-intumescent fire-retardant coatings Recommended value

[0030] Table 1 shows that for non-intumescent fire-retardant coatings, the equivalent thermal conductivity coefficient is... With increasing design fire resistance rating and coating thickness, the overall trend is downward. This indicates that thicker coatings provide better insulation under fire conditions, resulting in a lower equivalent thermal conductivity coefficient. In practical engineering applications, the appropriate coating can be selected within the corresponding range based on the design fire resistance rating requirements of the steel components. Estimated value.

[0031] Taking the FP-3 indoor non-intumescent fire-retardant coating as a typical example, under the standard temperature rise curve, when the design fire resistance limit of this coating is 1.5 hours and the actual application thickness is 16±2mm, its... The estimated calibration result is approximately 0.20 W / (m·K); when the design fire resistance limit is 3.0 hours and the actual construction thickness is 30±2 mm, The estimated calibration result is approximately 0.13 W / (m·K); when the design fire resistance limit is 4.0 hours and the actual construction thickness is 40±2 mm, The calibration result is approximately 0.11 W / (m·K). This calibration result is in high agreement with the recommended values ​​listed above.

[0032] It is important to note that the fire resistance rating of non-intumescent fire retardant coatings is significantly affected when using hydrocarbon fire temperature rise curves for testing. For example, for the same batch of FP-10 non-intumescent fire retardant coating, under the standard temperature rise curve, a coating thickness of 30±2mm corresponds to a fire resistance rating of 2.0 hours; however, under the HC fire temperature rise curve, the coating thickness needs to be increased to 33±2mm to achieve the same 2.0-hour fire resistance rating. Correspondingly, the fire resistance rating calibrated under the HC curve... The value will be slightly higher than the calibration value under the standard curve. Since the temperature rise curve of an electric fire is characterized by extremely rapid initial temperature rise, its severity is similar to that of the HC curve. When applying this method to electric fire scenarios (electric fire temperature rise curve), the experimental data under the HC curve can be used as a reference for conservative selection to ensure the safety of the design.

[0033] (v) Intumescent fire-retardant coatings Recommended value The heat insulation mechanism of intumescent fire-retardant coatings differs fundamentally from that of non-intumescent fire-retardant coatings. At high temperatures, the coating of intumescent fire-retardant coatings foams and expands, forming a porous carbonaceous layer several to tens of times thicker than the original coating. This carbonaceous layer can block heat transfer from external heat sources to the substrate, acting as a heat insulation barrier. However, in scenarios with extremely rapid temperature rise, such as electrical fires (electric fire temperature rise curves), the formation process and stability of the foamed layer in intumescent coatings face severe challenges. Related studies show that when the foamed layer thickness is large, the coating weight increases, and the foamed layer is more prone to detachment under the influence of gravity and furnace draft. Therefore, simply increasing the coating thickness cannot improve the fire resistance limit.

[0034] Taking Company A's indoor intumescent fire-retardant coating for steel structures as an example, under the HC fire temperature rise curve, the fire resistance limit can reach 1.83 hours when the coating thickness is 4.2 mm, and 2.5 hours when the coating thickness is 4.6 mm. However, observation of the morphology of the carbon layer after foaming revealed that when the fire resistance limit was reached, the coating exhibited large-area cracking and peeling, and the steel beams showed a positive bending state and a certain degree of distortion. These failure modes are related to the calibration of the equivalent thermal conductivity. Factors that must be considered when pushing forward.

[0035] Using the above calibration method, based on the test data of intumescent fire retardant coatings of models P-1, P-2, P-3, P-4, P-5, P-6, P-7, P-8, P-9, P-10, P-11, P-12, P-13, and P-14 under standard temperature rise curves and HC hydrocarbon fire temperature rise curves, the intumescent fire retardant coatings were obtained. Recommended values ​​are shown in Table 2 below: Table 2 Equivalent thermal conductivity coefficient of intumescent fire-retardant coatings Recommended value

[0036] In Table 2, water-based intumescent fire retardant coatings refer to fire retardant coatings that use water as the dispersion medium, while solvent-based intumescent fire retardant coatings refer to fire retardant coatings that use organic solvents as the dispersion medium. Generally speaking, solvent-based intumescent fire retardant coatings form a denser carbonized layer at high temperatures, therefore their equivalent thermal conductivity is slightly lower than that of water-based products. For intumescent fire retardant coatings, the appropriate selection should be made in engineering applications. When calculating the value, it is recommended to take the middle value or slightly higher than the upper limit of the above range to avoid overestimating its thermal insulation performance.

[0037] (vi) Other types of protective layers Recommended value For fireproof board protection, such as 38mm calcium silicate board or vermiculite board, its equivalent thermal conductivity coefficient is... The following recommended values ​​can be used as a reference: 38mm thickness (corresponding to a 2.0-hour fire resistance limit). Take a value of 0.11~0.13 W / (m·K). Since fireproof boards do not undergo chemical changes similar to intumescent coatings at high temperatures, their performance is relatively stable. Therefore, the simplified calculation formula and steps for the temperature rise of non-intumescent protective layers can be directly applied without introducing a correction factor. For composite protection systems, which consist of different functional layers, the overall equivalent thermal conductivity of the system is... The following recommended values ​​can be used as a reference: Taking 0.08~0.10 W / (m·K), the corresponding equivalent thermal resistance Approximately 0.45-0.50m 2 • K / W (corresponding to a 4.0-hour fire resistance limit). Similarly, the simplified calculation formula for the temperature rise of the non-expansion protective layer can be directly used.

[0038] (vii) Equivalent thermal conductivity Summary of determination methods In practical engineering applications, when it is necessary to determine the temperature rise performance of a protected steel component under electrical fire conditions, the equivalent thermal conductivity coefficient can be determined as follows: : First, determine the specific type of fire-resistant material used for the protected steel component (non-intumescent or intumescent, water-based or solvent-based). Then, based on the design fire resistance rating requirements of the steel component, find the corresponding material type and design fire resistance rating in the recommended value table shown in Table 1 or Table 2 (or a more detailed corresponding table in the database). The range of values ​​is determined; finally, a specific value is selected from the range, usually the middle value or finely adjusted based on practical engineering experience, as the equivalent thermal conductivity coefficient of the protective layer. .

[0039] Assuming the steel beam's design fire resistance rating is 3.0 hours, a non-intumescent fire-retardant coating of type FP-8 is selected, with a measured coating thickness δ of 30 mm. Based on the recommended values ​​in step S102, the following is selected... =0.13 W / (m·K). Substituting into the above formula: The equivalent thermal resistance of the protective layer is then... It is 0.23 m 2 • K / W. When the protective layer is heterogeneous or multi-layered (e.g., a composite coating system of primer + fire-retardant coating + topcoat), the thermal resistance of each layer can be calculated separately and then summed to obtain the total thermal resistance. Alternatively, the overall equivalent thermal conductivity of the composite protection system can be obtained through overall experimental calibration and then substituted into this formula for calculation.

[0040] As described above, the determination of the equivalent thermal conductivity coefficient is based on over 42 full-size steel component fire resistance tests conducted at the National Fireproof Building Materials Quality Inspection and Testing Center. This was achieved through a rigorous reverse calibration procedure, resulting in a publicly recommended value table for different protective layer types and thicknesses, including non-expansion and expansion types. These parameters comprehensively consider complex effects such as the physicochemical changes of materials at high temperatures and interfacial thermal resistance. By considering factors such as material heat transfer, potential physicochemical changes, and interfacial thermal resistance with the steel substrate, the equivalent thermal resistance of the protective layer is obtained, enabling an accurate description of its thermal changes.

[0041] In one embodiment of the present invention, obtaining the equivalent thermal conductivity coefficient of the protective layer based on the type and thickness of the protective layer includes: obtaining the relationship between the corresponding target thickness and the fire resistance limit based on the type of the protective layer; obtaining the target fire resistance limit based on the thickness of the protective layer and the relationship between the target thickness and the fire resistance limit; and obtaining the equivalent thermal conductivity coefficient based on the target fire resistance limit.

[0042] As described above, by establishing the relationship between the target thickness, fire resistance limit, and equivalent thermal conductivity, a matching equivalent thermal conductivity can be obtained based on the thickness of the protective layer, thereby accurately describing the temperature characteristics of the target steel structure.

[0043] In one embodiment of the present invention, the method further includes: if the protective layer is a non-intumescent fire-retardant coating, the relationship between the target thickness and the fire resistance limit includes: The first fire resistance limit corresponds to a thickness of 17-26 mm, with an equivalent thermal conductivity coefficient ranging from 0.18 to 0.22 W / (m·K). A fire resistance limit of 2 hours corresponds to a thickness of 21-30 mm, with an equivalent thermal conductivity coefficient ranging from 0.15 to 0.18 W / (m·K). The second fire resistance limit corresponds to a thickness of 30-38 mm, with an equivalent thermal conductivity coefficient ranging from 0.12 to 0.15 W / (m·K). The third fire resistance limit corresponds to a thickness of 38-43 mm, with an equivalent thermal conductivity coefficient ranging from 0.10 to 0.12 W / (m·K). The fire resistance limit duration is: first fire resistance limit duration < second fire resistance limit duration < third fire resistance limit duration < fourth fire resistance limit duration. For example, the first fire resistance limit duration is 1.5 hours, the second fire resistance limit duration is 2 hours, the third fire resistance limit duration is 3 hours, and the fourth fire resistance limit duration is 4 hours. At the same time, a mapping relationship between target thickness, fire resistance limit and equivalent thermal conductivity can also be established based on functions.

[0044] As described above, by establishing the relationship between target thickness, fire resistance limit, and equivalent thermal conductivity for non-intumescent fire-retardant coatings, the temperature characteristics of the target steel structure can be accurately described when the protective layer of the target steel structure is a non-intumescent fire-retardant coating.

[0045] In one embodiment of the present invention, the method further includes: if the type of the protective layer is a water-based intumescent fire retardant coating, the relationship between the thickness of the protective layer and the equivalent thermal conductivity is: when the thickness is 1.4-4.6 mm, the equivalent thermal conductivity is 0.25~0.30 W / (m·K); if the type of the protective layer is a solvent-based intumescent fire retardant coating, the relationship between the thickness of the protective layer and the equivalent thermal conductivity is: when the thickness is 1.8-5.5 mm, the equivalent thermal conductivity is 0.22~0.28 W / (m·K).

[0046] As described above, this embodiment specifically establishes the relationship between thickness and equivalent thermal conductivity for water-based intumescent fire retardant coatings and solvent-based intumescent fire retardant coatings, respectively. This allows for an accurate description of the temperature characteristics of the target steel structure even when the protective layer of the target steel structure is a water-based or solvent-based intumescent fire retardant coating.

[0047] In other words, by solving and outputting the two core thermal indicators, equivalent thermal resistance and equivalent thermal conductivity, this invention provides a comparable quantitative evaluation scale for the thermal insulation performance of fire protection materials of different types, models, and thicknesses. Designers can intuitively compare the protective efficacy of water-based and solvent-based intumescent coatings and non-intumescent coatings at various fire resistance ratings, thereby scientifically balancing material usage and protective effect while meeting the safety requirements of the specifications, and achieving the selection of fire protection measures.

[0048] In one embodiment of the present invention, the electric fire temperature rise curve function includes: ; In the formula, The furnace ambient temperature at time t corresponds to the firing time. The initial ambient temperature is denoted as 20℃; t is the fire exposure time, calculated from the start of the fire exposure, in minutes (min); A, B, and C are constants. The electrical fire temperature rise curve function reflects the temperature-time variation pattern during the development of fires in electrical facility locations (such as substations and converter stations) where high-polymer organic materials (such as wire and cable insulation materials) are the main combustibles.

[0049] Please refer to Figure 3The temperature-time relationships of the heating curves for electrical fires (electrical fire heating curve), ISO-834 standard heating curves (fiber fires), and HC hydrocarbon fire heating curves are shown. Referring to the relevant provisions of "Optional and Additional Test Procedures for Fire Resistance Testing of Building Components" (GB / T 26784-2011), the electrical fire heating curve is specifically used to simulate the heating conditions for testing the fire resistance performance of penetrating facilities, fire compartments, and load-bearing components in power plants or power transmission and distribution facilities.

[0050] like Figure 3 As shown, compared to the ISO-834 standard temperature rise curve, the most significant characteristic of the temperature rise curve for electrical fires is its extremely rapid initial temperature increase rate. According to relevant research (Chen et al., 2025), the temperature rise curve for electrical fires can raise the ambient temperature to approximately 1000°C within 15 minutes of the fire starting, while the ISO-834 standard curve requires approximately 100 minutes to reach the same temperature. This rapid temperature rise characteristic places more stringent requirements on the fire protection of steel structures.

[0051] In this embodiment, the heating curve function of an electrical fire The expression is: ; As described above, the temperature rise curve function in this embodiment was derived by a standardization organization or relevant research institution based on extensive experimental data from power facility fires. It reproduces the extreme rapid temperature rise of polymeric combustibles in power facilities, which quickly climbs to approximately 1000°C within the first 15 minutes of a fire. Compared to the conventional application of standard curves for fibrous fires, this design ensures that the furnace temperature environment used for temperature rise calculations closely matches the actual fire risk of substations. This effectively avoids the drawbacks of insufficient or excessive protective layer thickness design due to deviations in the temperature rise curve, significantly improving the specificity and safety redundancy of fire protection design. Using this curve as input for subsequent calculations ensures that the temperature rise calculation results match the actual fire risk of power facilities, avoiding evaluation biases caused by directly applying temperature rise curves for fibrous fires.

[0052] In one embodiment of the present invention, the method includes: obtaining the equivalent thermal resistance and the heating curve function of electrical fire Then, the temperature was substituted into a pre-constructed simplified calculation formula for the temperature rise of the protected steel component to calculate the core temperature of the steel component at fire exposure time t. Specifically: If the protective layer is a non-intumescent fire-retardant coating, then the formula for calculating the temperature rise of the target type is: ; If the protective layer is an intumescent fire-retardant coating, the formula for calculating the temperature rise of the target type is: ; in, The core temperature of the steel component is given by the fire exposure time t. The initial ambient temperature (default is 20℃). The furnace ambient temperature at time t is calculated from the electric fire heating curve function in step S101. The equivalent thermal resistance is given by k, a correction factor, and t, the exposure time (in minutes). 235.5 is the lumped parameter constant, calculated based on typical characteristic parameters and dimensions of steel components. The formula indicates that the core temperature of the steel component... It exhibits an exponential, gradual change over time t, gradually approaching the ambient temperature inside the furnace. The equivalent thermal resistance of the protective layer The larger the diameter, the slower the heating rate of the steel component, indicating a better fire protection effect.

[0053] The simplified temperature rise calculation formula in this embodiment is derived based on the lumped parameter method. The basic assumptions of the lumped parameter method are: since the thermal conductivity of steel is much greater than that of fireproof materials, the internal thermal resistance of the steel component can be ignored, and the temperature of the entire steel component can be considered uniform at any given time; heat transfer is mainly controlled by the thermal resistance of the protective layer. Based on the basic principles of the lumped parameter method, the energy conservation equation for the protected steel component is: ; In the formula: ρ is the density of steel, taken as 7850 kg / m³. 3 Where c is the specific heat capacity of steel, taken as 0.6 kJ / (kg·K); V is the fire-exposed volume of the steel component; A is the fire-exposed surface area of ​​the steel component; V / A is the section modulus of the steel component. For typical steel beams and columns commonly used in power facilities (with three sides exposed to fire), the section modulus V / A is approximately 0.05 m. Substituting the above parameters and rearranging the differential equation, we obtain the simplified calculation formula described above.

[0054] As described above, the simplified temperature rise calculation formula derived from the lumped parameter method condenses the thermal insulation performance of the protective layer into an equivalent thermal resistance, and directly presents the relationship between the core temperature of the steel component and the fire exposure time in an explicit analytical form. The calculation process involves only simple algebraic operations. This changes the traditional coarse mode of fire resistance limit method, which can only provide discrete-time ratings, and eliminates the need for complex software such as finite element method. It allows ordinary designers to quickly obtain the real-time temperature of the component at any time, greatly improving the efficiency and accessibility of the method in the fire protection design of steel structures for power facilities. At the same time, the calculation formula can continuously output the core temperature of the steel component at multiple moments throughout the fire exposure process, forming a complete temperature rise history curve, fully demonstrating the thermal response evolution of the structure from the initial fire exposure to the fire resistance limit, overcoming the limitation of traditional methods that only focus on the final fire resistance limit. Furthermore, the calculation parameters are directly adaptable to typical three-sided fire-exposed hot-rolled H-beams or I-beams in power facilities, without the need for complex section shape factor corrections, further enhancing the direct usability and convenience of this method in the practical fire protection design of prefabricated steel structures in substations.

[0055] In one embodiment of the present invention, if the protective layer is an intumescent fire-retardant coating, the effective foaming thickness of the protective layer is obtained; the equivalent thermal resistance is calculated by substituting the thickness of the protective layer with the effective foaming thickness. For steel components protected by intumescent fire-retardant coatings, the insulation mechanism is more complex than that of non-intumescent coatings because the coating foams and expands at high temperatures, forming a carbonized layer. Especially in rapidly heating scenarios such as electrical fires, the expansion, detachment, and cracking of the foamed layer significantly affect its insulation performance. Therefore, when performing temperature rise calculations for steel components protected by intumescent fire-retardant coatings, the aforementioned formula needs to be modified: Introducing effective foam thickness Calculating equivalent thermal resistance by replacing the original coating thickness δ Effective foaming thickness The calculation formula is: ; Right now, .

[0056] As described above, the formula reflects the effect of the thickness of the intumescent fire-retardant coating on the equivalent thermal resistance: when the coating thickness δ is small (δ≤2mm), the coating can fully foam, and the effective foamed thickness can reach more than 10 times the original thickness; when the coating thickness δ is large (δ>2mm), due to uneven heating inside the coating and the inability of the foaming gas to fully expand, the ratio of the effective foamed thickness to the original thickness is significantly reduced; and when δ>5mm, further increasing the coating thickness has very limited effect on improving the fire resistance limit.

[0057] In one embodiment of the present invention, the method further includes: obtaining the correction coefficient based on the thickness of the protective layer; the relationship between the thickness of the protective layer and the correction coefficient includes: ; Wherein, δ is the thickness of the protective layer.

[0058] As described above, this formula, through a correction coefficient k, macroscopically reflects the thermal insulation performance degradation effect caused by the failure behavior of the foamed layer, such as detachment and cracking, under rapidly rising high-temperature fires, making the calculation results closer to engineering reality. Furthermore, addressing the practical engineering challenge of the foamed layer's tendency to detach and crack under the rapid heating of intumescent fire-resistant coatings in electrical fires, the introduction of the concept of effective foaming thickness based on experimental data fitting and a thickness correction coefficient allows for a macroscopic and quantitative description of the thermal insulation performance degradation behavior caused by high-temperature failure. This overcomes the inherent limitation of existing simplified calculation methods that cannot consider the nonlinear thermal response of intumescent coatings, making the predicted temperature rise of steel components protected by this type of coating closer to the actual failure mode and avoiding safety hazards caused by overestimating the effectiveness of the foamed layer.

[0059] By following steps 101-105 above, the temperature rise performance of the protected steel component under an electrical fire can be determined. The resulting core temperature of the steel component... It can serve as a basis for engineering designers to conduct structural fire safety assessments.

[0060] The above methods are illustrated with specific examples below: Case 1: This embodiment takes the main steel structure beam of a substation building as the object and uses non-intumescent fireproof coating as a fire protection measure.

[0061] (1) Project Overview and Input Parameters An indoor substation building uses a prefabricated steel structure, with one main beam designed for a fire resistance rating of 3.0 hours. This main beam is made of HN400×200 hot-rolled H-beams and is exposed to fire on three sides. The fire protection scheme uses FP-3 indoor non-intumescent steel structure fire-retardant coating, with a designed coating thickness of 30mm. After actual construction, the average coating thickness was measured to be δ=31mm. The main equipment inside the substation building consists of transformers and distribution cabinets. The combustible materials are primarily transformer oil and cable insulation materials. According to the "Optional and Additional Test Procedures for Fire Resistance Testing of Building Components" (GB / T 26784-2011), the fire type is classified as an electrical fire, and the electrical fire temperature rise curve (electrical fire temperature rise curve) should be used as the evaluation benchmark. That is, execute step 101.

[0062] (2) Determine the equivalent thermal conductivity coefficient

[0063] Based on the recommended values ​​of equivalent thermal conductivity for non-intumescent fire-retardant coatings listed in Table 1, for a design fire resistance limit of 3.0 hours and a coating thickness in the range of 30-38 mm, the equivalent thermal conductivity is... The value range is 0.12~0.15 W / (m·K). This embodiment selects the median value of this range, i.e. =0.135W / (m·K).

[0064] (3) Calculate the equivalent thermal resistance

[0065] The protective layer thickness δ=31 mm and the equivalent thermal conductivity coefficient are used. Substituting 0.135 W / (m·K) into the equivalent thermal resistance calculation formula: (2)-(3) That is, execute step 102.

[0066] (4) Calculate the core temperature of the steel component at different time points. :Will , =20℃ =0.230 m 2 Substituting K / W into the simplified calculation formula for the temperature rise of a non-expansion protective layer: ; Summarized as follows: ; The calculations were performed at six time points: t = 30 min, 60 min, 90 min, 120 min, 150 min, and 180 min. Steps 104 and 105 were executed, and the results are shown in Table 3 below. Table 3 Calculation Results of Case 1

[0067] (5) Verification of Method Accuracy: To verify the consistency between the calculation method of this embodiment and the physical laws represented by the experiment, the typical experimental measured data of FP-3 non-intumescent fire retardant coating under the ISO-834 standard temperature rise curve and coating thickness of 30±2mm were compared with the calculated values ​​of this method. It should be noted that this comparison aims to verify the effectiveness of the formula form and parameter calibration method, rather than directly verifying the temperature rise process under the electric fire temperature rise curve. The measured data were compared with the calculated temperature of the method of this embodiment at the same time point mentioned above, and the results are shown in Table 4: Table 4 Comparison of calculated and measured values ​​under non-expansive coating protection

[0068] As can be seen, throughout the entire 180-minute fire exposure period, the absolute value of the relative error between the core temperature of the steel component calculated by the method in this embodiment and the measured temperature is within 5%, far less than the 8% upper limit of acceptable error in engineering. This fully demonstrates the effectiveness and accuracy of the equivalent thermal conductivity calibration value and the simplified calculation formula for temperature rise provided in this embodiment. Table 4 shows that this type of non-intumescent fireproof coating exhibits extremely excellent thermal insulation performance under standard fire conditions, with a measured temperature of only 303.3℃ after 3.0 hours (180 minutes) of fire exposure. According to the calculation results in Table 3, under the more stringent electrical fire temperature rise curve, the calculated core temperature of the steel component after 3.0 hours is approximately 727℃. This quantitative result intuitively demonstrates the extreme threat of electrical fires and provides an important reference for engineering design, namely, the selection of fire protection with sufficient thickness and performance to ensure structural safety.

[0069] Case 2: Using intumescent fire-retardant coatings as a fire protection measure to demonstrate the specific application of the method in this embodiment for the protection of intumescent fire-retardant coatings in working conditions.

[0070] (1) Project Overview and Input Parameters A secondary steel beam in a substation building has a design fire resistance rating of 2.0 hours. This beam is made of HN400×200 hot-rolled H-beams and is exposed to fire on three sides. The fire protection scheme uses P-2 indoor intumescent steel structure fire-retardant coating with a designed coating thickness of 3.0mm. After actual construction, the average coating thickness was measured to be δ=3.1mm. This substation is an indoor substation, and the combustible materials are mainly high-polymer materials such as electrical wires and cables; the fire type is an electrical fire. Therefore, proceed with step 101.

[0071] (2) Determine the equivalent thermal conductivity coefficient

[0072] The equivalent thermal conductivity λ_i of the intumescent fire retardant coating is given in Table 2 above. P-2 is a water-based intumescent fire retardant coating with a suitable thickness δ range of 1.4~4.6 mm. The value ranges from 0.25 to 0.30 W / (m·K). This embodiment selects... =0.28 W / (m·K).

[0073] (3) Calculate the effective foaming thickness For intumescent fire-retardant coatings, the effective foaming thickness needs to be calculated first. : .

[0074] (4) Calculate the equivalent thermal resistance : That is, proceed to step 102.

[0075] (5) Determine the correction factor k: The coating thickness δ = 3.1 mm, which is in the range of 2 < δ ≤ 5 mm, so take the correction factor k = 1.4. And select the expansion-type temperature rise calculation formula. That is, execute step 103.

[0076] (6) Calculate the core temperature of the steel component at different time points.

[0077] Substituting the above parameters into the simplified calculation formula for the temperature rise of the expansion-type protective layer:

[0078] The calculations were performed at four time points: t = 30 min, 60 min, 90 min, and 120 min. Specifically, steps 104-105 were executed, and the results are shown in Table 5. Table 5 Calculation Results of Case 2

[0079] As shown in Table 5 above, after approximately 60 minutes of exposure to fire, the core temperature of the steel component reached around 776℃, exceeding the critical temperature of the steel structure (typically 538℃), indicating that the steel component had lost its load-bearing capacity at this point. This suggests that a 3.1mm thick P-2 intumescent fire retardant coating may not meet the 2.0-hour fire resistance limit requirement in electrical fire scenarios, necessitating optimized design measures such as increasing the coating thickness, replacing with a higher-performance fire retardant coating, or employing a composite protection system.

[0080] To verify the accuracy of the method in this embodiment for the protection of intumescent fire-retardant coatings, the calculated values ​​were compared with the measured temperature data of the P-2 type intumescent fire-retardant coating (coating thickness approximately 3.0 mm, standard temperature rise curve, measured fire resistance limit 2.0 hours) recorded in Appendix 1 of Document 1 during 120 minutes of fire exposure. Some of the measured temperature data of the specimen during the fire exposure process are shown in Table 6: Table 6 Comparison of calculated and measured values ​​under the protection of intumescent coatings.

[0081] In addition, the test results of P-14 intumescent fire-retardant coating (coating thickness 4.0±0.2mm) under the HC hydrocarbon fire temperature rise curve can be referenced. The specimen's measured fire resistance limit under the HC curve was 2.0 hours, and the measured temperature after 120 minutes of fire exposure was 534.6℃; while under the standard temperature rise curve, the measured fire resistance limit reached 2.5 hours, indicating a significant decrease in fire resistance performance under more severe HC scenarios. This data further corroborates the necessity and rationality of using the method of this embodiment to determine temperature rise performance in rapidly heating scenarios such as electrical fires.

[0082] Please refer to Figure 4 A terminal for determining the temperature rise performance of a steel structure includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor, when executing the computer program, implements the steps of the method for determining the temperature rise performance of a steel structure as described above.

[0083] In summary, this invention provides a method and terminal for determining the temperature rise performance of steel structures. The method first obtains the protective layer thickness of the protected steel component and a preset temperature rise curve function for an electrical fire. Second, based on the type and thickness of the protective layer, it determines the equivalent thermal conductivity coefficient obtained through reverse calibration using full-scale fire resistance test data. Then, it calculates the equivalent thermal resistance based on this coefficient and the thickness. Finally, it substitutes the equivalent thermal resistance and the electrical fire temperature rise curve into a pre-constructed simplified calculation formula to obtain the core temperature of the steel component at fire exposure time t. Furthermore, for intumescent fire-retardant coatings, it introduces an effective foaming thickness and a thickness correction coefficient to reflect the high-temperature failure effect. This method has the following significant technical contributions and advantages: Clear scenario adaptability: For the first time, a calculation method is proposed that combines the temperature rise curve of power fires specifically for power plants or power transmission and distribution facilities with a set of thermal parameters calibrated and recommended based on system fire resistance tests. This allows the calculation results to more realistically reflect the thermal response law of steel structures of power facilities under power fires, solving the problem that existing standards lack applicable calculation methods in power fire scenarios.

[0084] The parameter calibration is scientific and the data is reliable: the equivalent thermal conductivity coefficient involved in the method is derived from fire resistance test data of more than 42 sets of full-size steel components, and is obtained through rigorous back-calculation and fitting procedures. This testing work was completed by the National Fireproof Building Materials Quality Inspection and Testing Center, ensuring the data source is authoritative and reliable. This embodiment discloses the recommended values ​​of the parameters obtained from these test calibrations, making the implementation of the method possible.

[0085] Simple to calculate and highly practical for engineering: The method is ultimately given in the form of an explicit analytical formula. Designers only need to obtain two parameters: the thickness of the protective layer and the equivalent thermal conductivity coefficient. They can then obtain the core temperature of the steel component at any fire moment through simple algebraic calculations without the need for complex finite element analysis software.

[0086] It can reflect the nonlinear behavior of materials: For intumescent fire-retardant coatings, by introducing an effective foaming thickness and a thickness correction coefficient, it is possible to quantitatively describe the impact of nonlinear behaviors such as foaming and peeling of the coating at high temperatures on the thermal insulation performance, thus solving the technical defect that traditional simplified methods cannot take into account the special characteristics of such materials.

[0087] After testing and verification, the accuracy meets the requirements: Comparison with multiple sets of full-scale fire resistance test data shows that the absolute error between the calculated temperature and the measured temperature is within 8%. For fire protection design in building engineering, this level of accuracy fully meets the needs of actual engineering projects.

[0088] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for determining the temperature rise performance of steel structures, characterized in that, include: The thickness and type of the protective layer of the target steel structure are obtained, as well as a preset electrical fire temperature rise curve function; the electrical fire temperature rise curve function is obtained by fitting experimental data of electrical facility fires. The equivalent thermal resistance of the protective layer is obtained based on its type and thickness. Obtain the target type temperature rise calculation formula corresponding to the type of the protective layer; Substituting the equivalent thermal resistance and the electric fire temperature rise curve function into the target type temperature rise calculation formula, the core temperature of the target steel structure under different preset fire exposure times is obtained. The heating performance of the target steel structure is evaluated based on the core temperature.

2. The method for determining the temperature rise performance of a steel structure according to claim 1, characterized in that, The process of obtaining the equivalent thermal resistance of the protective layer based on its type and thickness includes: The equivalent thermal conductivity coefficient of the protective layer is obtained based on its type and thickness. The equivalent thermal resistance of the protective layer is obtained based on the thickness of the protective layer and the equivalent thermal conductivity coefficient.

3. The method for determining the temperature rise performance of a steel structure according to claim 2, characterized in that, The process of obtaining the equivalent thermal conductivity coefficient of the protective layer based on its type and thickness includes: The relationship between the target thickness and the fire resistance limit is obtained according to the type of the protective layer. The target fire resistance limit is obtained based on the thickness of the protective layer and the relationship between the target thickness and the fire resistance limit. The equivalent thermal conductivity coefficient is obtained based on the target fire resistance limit.

4. The method for determining the temperature rise performance of a steel structure according to claim 3, characterized in that, Also includes: If the protective layer is a non-intumescent fire-retardant coating, the relationship between the target thickness and the fire resistance limit includes: The first fire resistance limit corresponds to a thickness of 17-26 mm, and the equivalent thermal conductivity coefficient ranges from 0.18 to 0.22 W / (m·K). The second fire resistance limit corresponds to a thickness of 21-30mm, and the equivalent thermal conductivity coefficient ranges from 0.15 to 0.18 W / (m·K). The third fire resistance limit corresponds to a thickness of 30-38mm, and the equivalent thermal conductivity coefficient ranges from 0.12 to 0.15 W / (m·K). The fourth fire resistance limit corresponds to a thickness of 38-43 mm, and the equivalent thermal conductivity coefficient ranges from 0.10 to 0.12 W / (m·K). The first fire resistance rating duration is less than the second fire resistance rating duration, the second fire resistance rating duration is less than the third fire resistance rating duration, and the third fire resistance rating duration is less than the fourth fire resistance rating duration.

5. The method for determining the temperature rise performance of a steel structure according to claim 2, characterized in that, Also includes: If the protective layer is a water-based intumescent fire retardant coating, the relationship between the thickness of the protective layer and the equivalent thermal conductivity is as follows: when the thickness is 1.4-4.6 mm, the equivalent thermal conductivity is 0.25~0.30 W / (m·K); If the protective layer is a solvent-based intumescent fire retardant coating, the relationship between the thickness of the protective layer and the equivalent thermal conductivity is as follows: when the thickness is 1.8-5.5 mm, the equivalent thermal conductivity is 0.22~0.28 W / (m·K).

6. The method for determining the temperature rise performance of a steel structure according to claim 1, characterized in that, The electric fire temperature rise curve function includes: ； In the formula, The furnace ambient temperature at time t corresponds to the firing time. The initial ambient temperature is t, the fire exposure time is t, and A, B, and C are constants.

7. The method for determining the temperature rise performance of a steel structure according to claim 1, characterized in that, The term includes: If the protective layer is a non-intumescent fire-retardant coating, then the formula for calculating the temperature rise of the target type is: ； If the protective layer is an intumescent fire-retardant coating, the formula for calculating the temperature rise of the target type is: ； in, The core temperature of the steel component is given by the fire exposure time t. The initial ambient temperature, The furnace ambient temperature at time t corresponds to the firing time. The equivalent thermal resistance is given by k, which is a correction factor.

8. The method for determining the temperature rise performance of a steel structure according to claim 7, characterized in that, If the protective layer is an intumescent fire-retardant coating, then obtain the effective foaming thickness of the protective layer; The equivalent thermal resistance is calculated by substituting the thickness of the protective layer with the effective foaming thickness.

9. The method for determining the temperature rise performance of a steel structure according to claim 7, characterized in that, Also includes: The correction coefficient is obtained based on the thickness of the protective layer; The relationship between the thickness of the protective layer and the correction factor includes: ； Wherein, δ is the thickness of the protective layer.

10. A terminal for determining the temperature rise performance of a steel structure, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements each step of the method for determining the heating performance of a steel structure as described in any one of claims 1 to 9.

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