Evaluation method

Abstract

To provide an evaluation method that allows for a simpler and more detailed assessment of how easily an H-shaped steel beam covered with fire-resistant material heats up. [Solution] The method includes a heating perimeter calculation step, a perimeter ratio calculation step for calculating the heating perimeter ratio of the plate element, and a comparison step for comparing the heating perimeter ratios of the plate elements, wherein the calculation conditions in the heating perimeter calculation step include the fact that the heating perimeter of the plate element is calculated by at least one of the following formulas when the fire-resistant material has two sides and one bottom surface, the sides of the fire-resistant material are positioned opposite the web, the upper end of the sides of the fire-resistant material is in contact with the side of the upper flange, the lower end of the sides of the fire-resistant material is in contact with the side of the lower flange, and the bottom surface of the fire-resistant material is in contact with the bottom surface of the lower flange, and the value of the coefficient is set according to the construction state of the fire-resistant material. H SR(UF) =L×α1+L×α2 H SR(W) =2H-(L×α1+L×α2)-(L×β1+L×β2) H SR(LF) =L×β1+L×β2+W

Description

Technical Field

[0001] The present disclosure relates to an evaluation method. Background Art

[0002] Conventionally, the proneness of steel materials to heat up during a fire has been evaluated through experiments, numerical analysis, or other methods. In addition, since evaluation via experiments and numerical analysis may require time or cost, a method using a heated perimeter ratio is known as an alternative evaluation method for evaluating the proneness of steel materials to heat up during a fire instead of experiments and numerical analysis.

[0003] For example, as described in Non-Patent Document 1, the proneness of H-shaped steel to heat up is evaluated using a heated perimeter ratio calculated from the cross-sectional area and the heated perimeter of an H-shaped steel beam subjected to three-sided heating. Prior Art Documents Non-Patent Documents

[0004] Non-Patent Document 1 "Steel Structure Fire Resistance Design Guidelines", published by the Architectural Institute of Japan, issued June 5, 2017, pp.109-116 Summary of the Invention Problem to be Solved by the Invention

[0005] However, for H-shaped steel beams coated with a refractory material, a method of calculating the heated perimeter ratio for each plate element and relatively evaluating the proneness to heat up has not been studied.

[0006] The present disclosure has been made in view of the foregoing circumstances, and an object thereof is to provide an evaluation method capable of more simply and detailedly evaluating the proneness to heat up of an H-shaped steel beam coated with a refractory material. Means for Solving the Problem

[0007] An evaluation method according to one aspect of the present disclosure is an evaluation method for evaluating how easily an H-shaped steel beam, which is a beam made of H-shaped steel and covered with a fire-resistant material, heats up when heated during a fire, and includes a heating circumference calculation step of calculating the heating circumference of each plate element according to calculation conditions, and a circumference ratio calculation step of calculating the heating circumference ratio of each plate element by dividing the heating circumference of each plate element calculated in the heating circumference calculation step by the cross-sectional area of ​​each plate element, wherein the calculation conditions in the heating circumference calculation step are that the fire-resistant material has two sides and one bottom surface, When the side surface of the fire-resistant material is positioned opposite the web, and the upper end of the side surface of the fire-resistant material is in contact with the side surface of the upper flange, and the lower end of the side surface of the fire-resistant material is in contact with the side surface of the lower flange, and the lower surface of the fire-resistant material is in contact with the lower surface of the lower flange, the heating circumference of the upper flange is calculated using the following formula (5), the heating circumference of the web is calculated using the following formula (6), and the heating circumference of the lower flange is calculated using the following formula (7), the value of the coefficient is set according to the installation state of the fire-resistant material. H SR(UF) =L×α1+L×α2···(5) H SR(W) =2H-(L×α1+L×α2)-(L×β1+L×β2)...(6) H SR(LF) =L×β1+L×β2+W···(7) H SR(UF) : Heating circumference of the upper flange H SR(W) : Heating circumference of the web H SR(LF) : Heating circumference of the lower flange L: Flange width on one side (mm) H: Beam depth (mm) W: Flange width (mm) α1, α2, β1, β2: coefficients An evaluation method according to another aspect of the present disclosure is an evaluation method for evaluating how easily H-shaped steel heats when an H-shaped steel beam, which is a beam formed of H-shaped steel and covered with a refractory material, is heated during a fire, the method comprising: a heated perimeter calculating step of calculating a heated perimeter for each of said plate elements in accordance with calculation conditions; and a perimeter ratio calculating step of calculating a heated perimeter ratio for each plate element by dividing the heated perimeter for each plate element calculated in said heated perimeter calculating step by the cross-sectional area of each said plate element, wherein said calculation conditions in said heated perimeter calculating step are when said refractory material is arranged on the surface of said H-shaped steel along the shape of said H-shaped steel, the method includes at least one of: calculating the heated perimeter of the upper flange using the following formula (11), calculating the heated perimeter of the web using the following formula (12), and calculating the heated perimeter of the lower flange using the following formula (13). H SR(UF) =W···(11) H SR(W) =2H···(12) H SR(LF) =2W···(13) H SR(UF) : Heated perimeter of upper flange H SR(W) : Heated perimeter of web H SR(LF) : Heated perimeter of lower flange H: Beam depth (mm) W: Flange width (mm) Effects of the Invention

[0008] According to an embodiment of the present disclosure, it is possible to provide an evaluation method capable of evaluating how easily an H-shaped steel beam covered with a refractory material heats more simply and in detail. Brief Description of the Drawings

[0009] [Figure 1] It is a schematic cross-sectional view of an H-shaped steel beam. [Figure 2] It is a schematic cross-sectional view of an H-shaped steel beam in a state where H-shaped steel is covered with a refractory material in a U-shape. [Figure 3] It is a flowchart showing the evaluation method of the present embodiment. [Figure 4] This is a schematic cross-sectional view of an H-shaped steel beam, where the surface of the H-shaped steel is covered with fire-resistant material in accordance with the shape of the H-shaped steel. [Figure 5] This is the result of numerically evaluating the ease with which each plate element of the H-shaped steel beam in the first embodiment heats up through analysis. [Figure 6] This graph shows the relationship between the coefficients α1, α2, β1, and β2 and the plate element heating perimeter ratio in the H-shaped steel beam of the first embodiment. [Figure 7] This is the result of numerically evaluating the ease with which each plate element of the H-shaped steel beam in the second embodiment heats up through analysis. [Modes for carrying out the invention]

[0010] First, we will explain the technical knowledge that led to the development of the evaluation method according to this embodiment.

[0011] Traditionally, the performance of steel materials has been evaluated by assessing how easily they heat up through experiments or numerical analysis. Furthermore, as a simple method for evaluating how easily steel heats up without requiring experiments or numerical analysis, it is known that the heating circumference ratio is calculated based on the cross-sectional area and heating circumference of the steel being heated during a fire, for example, to evaluate how easily the steel heats up during a fire.

[0012] Since the heating circumference ratio can be determined by relatively simple calculations, evaluation using the heating circumference ratio can reduce, for example, time and cost compared to evaluation by experiment or numerical analysis.

[0013] In recent years, H-beams with thinner flanges or webs compared to conventional H-beams, such as thin-flange H-beams and thin-web H-beams, are sometimes used as beams. However, conventional evaluations based on the heating circumference ratio have not always accurately evaluated the ease of heating in H-beams 10 with special shapes such as thin webs 11 and thin flanges 12. For example, a thin web 11 may refer to a web 11 with a thickness of 3 mm to 9 mm. A thin flange 12 may refer to a flange 12 with a thickness of 4 mm to 12 mm.

[0014] Figure 1 shows a schematic cross-sectional view of the H-shaped steel beam 1 (the covering is not shown). In the H-shaped steel beam 1 shown in Figure 1, the upper surface of the H-shaped steel 10 (the upper surface of the upper flange 12a) is in contact with the concrete slab. Hereafter, in the H-shaped steel beam 1, the beam depth of the H-shaped steel beam 1 is H, the flange width is W, and the thickness of the web 11 is t. w The thickness of the upper and lower flanges 12 is t f Let's assume that.

[0015] Conventional evaluations based on heating circumference ratio have not adequately considered the ease of heating under various conditions, such as when fire-resistant material 20 is applied to an H-shaped steel beam, as shown in Figure 2. The fire-resistant material 20 is a component that protects the H-shaped steel beam 1 by, for example, covering it to suppress heat transfer to the H-shaped steel beam 10 during a fire. Therefore, when the fire-resistant material 20 is applied to the H-shaped steel beam 1, the temperature change of the H-shaped steel beam 10 during a fire will differ from the temperature change of the H-shaped steel beam 10 when the fire-resistant material 20 is not applied. When the fire-resistant material 20 is applied to the H-shaped steel beam 1, the plate elements of the H-shaped steel beam 10 are not directly exposed to high temperatures, so it was not always possible to simply consider the perimeter of the plate elements as the heated perimeter. Therefore, conventional evaluations based on the heated perimeter ratio sometimes lacked sufficient accuracy in evaluating how easily an H-shaped steel beam heats up when the fire-resistant material 20 is applied to it.

[0016] In response to this, the inventors conceived of defining the conditions for calculating the heating perimeter for each plate element according to various conditions, such as the state of application of the fire-resistant material 20 to the H-shaped steel beam 1.

[0017] The specific configuration of the evaluation method according to this embodiment will be described below. In explanations, ranges indicated by a "~" symbol generally include the values ​​at both ends of the range as the lower and upper limits.

[0018] <First Embodiment> Figure 2 shows a schematic cross-sectional view of an H-shaped steel beam 1 in which a fire-resistant material 20 is covered in a U-shape on an H-shaped steel beam 10. In the example shown in Figure 2, the H-shaped steel beam 10 is covered with a U-shaped fire-resistant material 20. Specifically, the fire-resistant material 20 has two side surfaces 21 and one bottom surface 22. The side surfaces 21 of the fire-resistant material 20 are positioned opposite the web 11, and the upper end of the side surfaces 21 of the fire-resistant material 20 is in contact with the side surface of the upper flange 12a, and the lower end of the side surfaces 21 of the fire-resistant material 20 is in contact with the side surface of the lower flange 12b. The bottom surface 22 of the fire-resistant material 20 is in contact with the bottom surface of the lower flange 12b, and the fire-resistant material 20 is wrapped around the H-shaped steel beam 1 in a U-shape.

[0019] The method of covering the H-shaped steel beam 10 with fire-resistant material 20 in a U-shape is not limited, but for example, it may be done by wrapping fire-resistant covering material around the H-shaped steel beam 10, or for example, by fixing plate-shaped fire-resistant covering material to the bottom and sides of the H-shaped steel beam 10.

[0020] In the first embodiment, the ease with which each plate element of the H-shaped steel beam 1 heats up is evaluated, with the H-shaped steel 10 covered with a fire-resistant material 20 in a U-shape.

[0021] The following describes how to evaluate the ease with which three plate elements heat up: the upper flange 12a (UF), which is a flange 12(F) located on the upper side of the H-shaped steel beam 1; the lower flange 12b (LF), which is a flange 12(F) located on the lower side of the H-shaped steel beam 1; and the web 11 (WE), which is positioned perpendicularly between the two flanges 12.

[0022] The H-shaped steel beams 10 that are subject to evaluation by the evaluation method of this disclosure are not limited. The H-shaped steel beams 10 may be manufactured, for example, by individually rolling the flange 12 and the web 11 and then joining them by welding, or they may be manufactured, for example, by integrally forming the flange 12 and the web 11 by rolling.

[0023] Figure 3 shows a flowchart of the evaluation method in this embodiment. The evaluation method of the first embodiment includes a cross-sectional area calculation step S110 for calculating the cross-sectional area of ​​each plate element, a heating perimeter calculation step S120 for calculating the heating perimeter of each plate element according to calculation conditions, a perimeter ratio calculation step S130 for calculating the heating perimeter ratio of each plate element (hereinafter sometimes referred to as the plate element heating perimeter ratio), and a comparison step S140 for comparing the magnitude of the plate element heating perimeter ratios. In each of these steps, the cross-sectional area, heating perimeter, and heating perimeter ratio may be calculated by a designer (human) or by a computer. The evaluation method only needs to include at least the heating circumference calculation step S120 and the circumference ratio calculation step S130, and does not need to include the cross-sectional area calculation step S110. For example, the cross-sectional area, heating circumference, and heating circumference ratio may be pre-stored in a computer (storage device). Note that the flange width W, beam depth H, and thickness t of the upper and lower flanges 12 of the H-shaped steel beam 1 are specified. f , and the thickness of the web 11 t w It may be stored in a computer.

[0024] (Cross-sectional area calculation step S110) In step S110 of this embodiment, the cross-sectional area of ​​each plate element of the H-shaped steel beam 10 is calculated. In the H-shaped steel beam 1 shown in Figure 2, the cross-sectional area of ​​each plate element of this embodiment (mm 2 The calculation of ) can be done, for example, as follows: Of the upper and lower flanges 12, the cross-sectional area of ​​the upper flange 12a is A s(UF) The cross-sectional area of ​​web 11 is A s(WE)、 The cross-sectional area of ​​the lower flange 12b is A s(UF)In this case, the cross-sectional area of ​​each plate element can be calculated using the following equations (1), (2), and (3). Note that in the illustrated example, the flange width W and thickness t are between the upper and lower flanges. f Since they are equal, the cross-sectional areas of the upper flange and the lower flange are equal, but the width W or thickness t of the upper flange and the lower flange are equal. f If at least one of them is different, the cross-sectional areas of the upper flange and the lower flange may be different. A s(UF) =W × t f ...(1) A s(W) =(H-2×t f )×t w ...(2) A s(LF) =W × t f ...(3)

[0025] (Heating circumference calculation step S120) In the heating perimeter calculation step S120 of this embodiment, the conditions for calculating the heating perimeter are defined for each plate element. Defining the conditions for calculating the heating perimeter means, for example, defining the portion to be considered as the heating perimeter for each plate element, or defining the length to be considered as the heating perimeter.

[0026] In the case of an H-beam with a space between the fire-resistant material and the H-beam, as in this embodiment, the inventors have found that, unlike in the case where there is no covering, it is necessary to consider heat transfer from the fire-resistant material and the space when calculating the vertical heating circumference (side heating circumference) of both the upper and lower flanges. Furthermore, they have found that by using the width of one side of the flange 12 (half of the flange width W) as a reference and multiplying this reference by a predetermined coefficient, the vertical heating circumference of both the upper and lower flanges can be calculated. In addition, by making it possible to calculate the vertical heating circumference of the upper and lower flanges 12, and the left and right sides (first direction D1 and second direction D2) of each upper and lower flange, using separate coefficients, it has been found that the plate element heating circumference ratio can be calculated accurately even when, for example, the upper and lower flange widths are different, or when the beam cross-section does not receive uniform heating from all sides (excluding the upper surface of the upper flange in contact with the concrete slab 100). In the case where the beam cross-section is not heated uniformly from all sides, for example, the H-shaped steel beam 1 may be heated from either the left or right side of the beam cross-section (first direction D1 or second direction D2).

[0027] In the following, the heating circumference of the vertical component of flange 12 is defined as H v The flange width on one side of the flange 12 (half of the flange width W) is L, and the coefficients are α1, α2, β1, and β2. Coefficient α1 represents the ratio of the one-sided vertical component on the first direction D1 side to the heating circumference of the upper flange 12a per side of the flange 12 (half of the flange width W, L = W / 2). Similarly, coefficient α2 represents the ratio of the one-sided vertical component on the second direction D2 side to the heating circumference of the upper flange 12a, coefficient β1 represents the ratio of the one-sided vertical component on the first direction D1 side to the heating circumference of the lower flange 12b, and coefficient β2 represents the ratio of the one-sided vertical component on the second direction D2 side to the heating circumference of the lower flange 12b.

[0028] Furthermore, in the case of an H-shaped steel beam covered in a U-shape with fire-resistant material 20, for example, the web 11 is insulated with air, so the web 11 is less likely to heat up compared to the upper and lower flanges 12. Therefore, in the heating circumference calculation step S120 of this embodiment, the calculation condition is that the heating circumference of the web 11 is the value obtained by subtracting the heating circumference of the vertical component of the flange 12 from the beam depth of the H-shaped steel beam 10.

[0029] In other words, according to the calculation conditions of the heating perimeter calculation step S120 in this embodiment, the heating perimeter (mm) of the plate element of the H-shaped steel beam 1 shown in Figure 4 is calculated by the following equations (5), (6), and (7). H SR(UF) =L×α1+L×α2···(5) H SR(W) =2H-(L×α1+L×α2)-(L×β1+L×β2)...(6) H SR(LF) =L×β1+L×β2+W···(7)

[0030] Furthermore, in the heating perimeter calculation step S120 of this embodiment, the coefficients α1, α2, β1, and β2 used in the above equations (5) to (7) are all between 1 / 10 and 1 / 3. Note that in the heating perimeter calculation step S120, the values ​​of the coefficients α1, α2, β1, and β2 used in the above equations (5) to (7) may be set according to the construction state of the fire-resistant material and the heating conditions. Depending on the construction state of the fire-resistant material and the heating conditions, for example, all the coefficient values ​​may be the same, all the coefficient values ​​may be different, or some of the coefficient values ​​may be different. Specifically, for example, when the H-shaped steel beam 1 is installed directly above a fire compartment, and the H-shaped steel beam 1 is heated from one side of the beam cross-section (either the left or right side, or the first or second direction), the heating perimeter for each plate element and the heating perimeter ratio of the plate elements can be calculated by setting the values ​​of the coefficients α1, α2, β1, and β2 to different values. As will be explained in more detail later, if the values ​​of the coefficients α1, α2, β1, and β2 are between 1 / 10 and 1 / 3, then in an H-shaped steel beam 1 constructed by wrapping the fire-resistant material 20 around it in a U-shape, as shown in Figure 4, the ease with which the plate elements heat up can be evaluated based on the heating circumference ratio of each plate element of the H-shaped steel 10, regardless of the shape of the H-shaped steel 10.

[0031] (Perimeter ratio calculation step S130) In the perimeter ratio calculation step S130 of this embodiment, the heating perimeter ratio R of the plate element of the H-shaped steel 10 is calculated. e The following is calculated. In the H-shaped steel 10 shown in Figure 2, the plate element heating circumference ratio (m) of this embodiment is calculated. -1 The calculation of ) can be done, for example, as follows: The heating circumference ratio of the upper flange 12a is R e(UF) The heating circumference ratio of web 11 is R e(WE)、 The heating circumference ratio of the lower flange 12b is R e(LF) In this case, the heating perimeter ratio of each plate element can be determined by the following equations (8), (9), and (10). Note that equations (8) to (10) below use the heating perimeter (mm) of each plate element calculated above, and the cross-sectional area (mm) of each plate element. 2 It is the result of dividing by ). R e(UF) =H sr(UF)÷A s(UF) ×1000···(8) R e(WE) =H sr(WE) ÷A s(WE) ×1000···(9) R e(LF) =H sr(LF) ÷A s(LF) ×1000···(10)

[0032] (Comparison step S140) In the comparison step S140, the heating perimeter ratio for each plate element calculated in the perimeter ratio calculation step S130 is compared. In the comparison step S140 of this embodiment, the relative magnitudes of the heating perimeter ratios for each plate element calculated in the perimeter ratio calculation step S130 are compared to determine the ranking of how easily each plate element heats up. Specifically, in the comparison step S140 of this embodiment, if, for example, the heating perimeter ratios of the plate elements are web 11 > lower flange 12b > upper flange 12a, then the ease of heating for each plate element is evaluated as web 11 > lower flange 12b > upper flange 12a.

[0033] Furthermore, the plate element heating circumference ratio calculated using the above method only needs to be usable for comparing their relative sizes. In other words, the plate element heating circumference ratio calculated using the above method only needs to be usable for determining the ranking of how easily each plate element heats up.

[0034] The calculation conditions for the heating perimeter of each plate element are not limited to those described above. For example, a coefficient may be set appropriately depending on the coating conditions (construction state) of the fire-resistant material 20.

[0035] With the evaluation method of the first embodiment, even in the case of H-shaped steel 10 covered with fire-resistant material 20 in a U-shape, which was difficult to evaluate using conventional evaluation methods that use the heating circumference ratio, the ease with which each plate element heats up can be evaluated by the heating circumference ratio of the plate elements. Furthermore, in the case of H-shaped steel beam 1, by appropriately setting the calculation conditions for the heating circumference of each plate element according to the construction state of the fire-resistant material 20, for example, the ease with which the H-shaped steel 10 heats up can be easily evaluated using the heating circumference ratio of the plate elements, regardless of the shape (dimensions) of the H-shaped steel 10.

[0036] <Second Embodiment> Figure 4 shows a schematic cross-sectional view of an H-shaped steel beam 1 in which a fire-resistant material is applied to the surface of the H-shaped steel 10 in accordance with the shape of the H-shaped steel 10. In the second embodiment, as shown in Figure 4, the ease with which each plate element of the H-shaped steel beam 1 heats up is evaluated when the surface of the H-shaped steel 10 is covered with fire-resistant material 20 in accordance with the shape of the H-shaped steel 10. The method of covering the surface of the H-shaped steel 10 with fire-resistant material 20 in accordance with the shape of the H-shaped steel 10 is not limited, but for example, it may be done by spraying a spray-on fire-resistant coating material onto the H-shaped steel 10.

[0037] The evaluation method flow of the second embodiment may be the same as that of the first embodiment. The cross-sectional area calculation step, the perimeter ratio calculation step, and the comparison step of the second embodiment may be the same as those of the first embodiment, so they are omitted from this description. The calculation conditions in the heating perimeter calculation step of the second embodiment are different from the calculation conditions in the heating perimeter calculation step of the first embodiment. The heating perimeter calculation step of the second embodiment will be described below.

[0038] (Heating circumference calculation step S120) In the heating perimeter calculation step S120 of this embodiment, the conditions for calculating the heating perimeter for each plate element are defined as follows.

[0039] In an H-shaped steel beam 10 where the surface of the H-shaped steel beam 10 is covered with fire-resistant material 20 in accordance with the shape of the H-shaped steel beam 10, none of the plate elements are insulated with air.

[0040] Therefore, according to the calculation conditions of the heating perimeter calculation step S120 in this embodiment, the heating perimeters of the plate elements of the H-shaped steel beam shown in Figure 4 are calculated using the following equations (11), (12), and (13), respectively. H SR(UF) =W···(11) H SR(W) =2H···(12) H SR(LF) =2W···(13)

[0041] In the evaluation method of the second embodiment, in an H-shaped steel beam 10 in which a fire-resistant material 20 is coated on the surface of the H-shaped steel beam 10 in accordance with the shape of the H-shaped steel beam 10, the ease with which each plate element heats up can be evaluated by the heating circumference ratio of the plate elements. [Examples]

[0042] The effects of one aspect of this disclosure will be further illustrated by the examples. However, the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effectiveness of this disclosure. This disclosure is not limited to these examples of conditions. This disclosure may adopt various conditions as long as they do not depart from the gist of this disclosure and achieve the objectives of this disclosure.

[0043] <First Example> We investigated the temperature changes of each plate element when an H-shaped steel beam, which is covered in a U-shape with fire-resistant material and has dimensions of "H-400×200×4×16", "H-400×200×16×4", "H-800×300×14×26", or "H-800×300×26×14", is heated. Note that "H-800×300×14×26" means that the beam depth H is 800 mm, the flange width W is 300 mm, and the web thickness t w 14mm, flange thickness t f This indicates an H-beam with a width of 26mm. "H-800×300×26×14" means a beam depth H of 800mm, flange width W of 300mm, and web thickness t w 26mm, flange thickness t f This shows an H-beam with a diameter of 14 mm. For the fire-resistant material, the verification was conducted using Makibee (registered trademark, Nichias Corporation, 20mm thick), a wrap-around fire-resistant coating material. Verification was carried out using both numerical analysis and the evaluation method of the second embodiment (a method for calculating the heating circumference ratio of plate elements). The numerical analysis was performed for comparison with the results obtained using the evaluation method of the second embodiment.

[0044] <Numerical Analysis> In the numerical analysis (heat conduction analysis), it was assumed that the outer surface of the fire-resistant material and the underside of the floor slab were heated according to the heating curve (standard heating curve, standard heating temperature curve) specified in ISO 834-11:2014 (hereinafter, ISO 834), and the temperature change of each plate element of the H-shaped steel during a fire was analyzed.

[0045] The results of the numerical analysis are shown in the graph in Figure 5. In Figure 5, the horizontal axis represents time (seconds) and the vertical axis represents temperature (°C). In Figure 5, (a) shows the results for "H-400×200×4×16", (b) shows the results for "H-400×200×16×4", (c) shows the results for "H-800×300×14×26", and (d) shows the results for "H-800×300×26×14".

[0046] By comparing how easily each plate element of the H-shaped steel beam was heated, we were able to evaluate the susceptibility of the plate elements of H-shaped steel beams of each size to heating as follows. As shown in Figure 5(a), when using H-beams of type "H-400×200×4×16", the susceptibility of plate elements to heating was web > lower flange > upper flange. As shown in Figure 5(b), when using H-beams of type "H-400×200×16×4", the susceptibility of plate elements to heating was lower flange > web > upper flange. As shown in Figure 5(c), when using H-beams of type "H-800×300×14×26", the susceptibility of plate elements to heating was web > lower flange > upper flange. As shown in Figure 5(d), when using H-beams of type "H-800×300×26×14", the susceptibility of plate elements to heating was lower flange > web > upper flange.

[0047] In the case of plate elements, being susceptible to heating may mean, for example, that the degree of temperature rise of the plate element per unit time is high, or for example, that the temperature is higher when heated for 1800 seconds or more based on the heating curve (standard heating curve, standard heating temperature curve) specified in ISO 834.

[0048] <Plate element heating circumference ratio> Next, the ease with which each plate element of the H-beam steel heated during a fire was evaluated using the plate element heating circumference ratio. The plate element heating circumference ratio was calculated using the method described in the second embodiment. The coefficients α1, α2, β1, and β2 in equations (12) to (15) were 1 / 1, 1 / 2, 1 / 3, 1 / 4, 1 / 10, and 1 / 20, respectively, to calculate the heating circumference ratio for each plate element. In this embodiment, the coefficients α1, α2, β1, and β2 were all set to the same value, assuming that the beam cross section was heated uniformly from all surfaces (excluding the upper surface of the upper flange in contact with the concrete slab 100).

[0049] Table 1 shows the results of the evaluation based on the heating perimeter ratio of the plate elements. In Table 1, the results of the evaluation based on the heating perimeter ratio of the plate elements and the results of the numerical analysis are shown in the same table for comparison.

[0050] [Table 1]

[0051] Comparing the results of the numerical analysis with the results of the plate element heating perimeter ratio yielded the following results. In the H-shaped steel beam using "H-400×200×4×16", regardless of whether the coefficients α1, α2, β1, and β2 were set to 1 / 1, 1 / 2, 1 / 3, 1 / 4, 1 / 10, or 1 / 20, the ranking of how easily each plate element heats up was the same in both the numerical analysis results and the results of the heating circumference ratio for each plate element using the coefficients. In other words, in the H-shaped steel beam using "H-400×200×4×16", the ranking of how easily each plate element heats up could be predicted by the heating circumference ratio of the plate elements, regardless of which coefficients were used. In H-shaped steel beams using "H-400×200×16×4", if the coefficients α1, α2, β1, and β2 were 1 / 3, 1 / 4, 1 / 10, or 1 / 20, the ranking of ease of heating for each plate element was the same as that obtained from the numerical analysis results and the results obtained from the heating circumference ratio for each plate element using the coefficients. In other words, in H-shaped steel beams using "H-400×200×16×4", if the coefficients α1, α2, β1, and β2 were 1 / 3, 1 / 4, 1 / 10, or 1 / 20, the ranking of ease of heating for each plate element could be predicted by the heating circumference ratio of the plate elements. In the H-shaped steel beam using "H-800×300×14×26", regardless of whether the coefficients α1, α2, β1, and β2 were set to 1 / 1, 1 / 2, 1 / 3, 1 / 4, 1 / 10, or 1 / 20, the ranking of ease of heating for each plate element was the same in both the numerical analysis results and the results of the heating perimeter ratio for each plate element using the coefficients. In other words, in the H-shaped steel beam using "H-800×300×14×26", the ranking of ease of heating for each plate element could be predicted by the heating perimeter ratio of the plate elements, regardless of which coefficients were used. In H-shaped steel beams using "H-800×300×26×14", if the coefficients α1, α2, β1, and β2 were 1 / 2, 1 / 3, 1 / 4, or 1 / 10, the ranking of ease of heating for each plate element was the same in both the numerical analysis results and the results of the plate element heating perimeter ratio using the coefficients. In other words, in H-shaped steel beams using "H-800×300×26×14", if the coefficients α1, α2, β1, and β2 were 1 / 2, 1 / 3, 1 / 4, or 1 / 10, the ranking of ease of heating for each plate element could be predicted by the plate element heating perimeter ratio.

[0052] Next, we examined the relationship between the coefficients α1, α2, β1, and β2 and the heating perimeter ratio of the plate element. Figure 6 shows a graph illustrating the relationship between the coefficients α1, α2, β1, and β2 and the heating perimeter ratio of the plate element. In Figure 6, the horizontal axis represents the coefficient values, and the vertical axis represents the heating perimeter ratio of the plate element (m -1 This represents the graph for "H-400×200×4×16", (b) the graph for "H-400×200×16×4", (c) the graph for "H-800×300×14×26", and (d) the graph for "H-800×300×26×14".

[0053] In each graph in Figure 6, the shaded areas indicate regions where the ranking of ease of heating for each plate element is the same, based on the results of numerical analysis and the plate element heating perimeter ratio using coefficients.

[0054] As shown in Table 2 and Figure 6, under the above conditions, regardless of the dimensions of the H-beam, if the coefficients α1, α2, β1, and β2 are between 1 / 10 and 1 / 3, the ranking of how easily each plate element heats up will be the same in both the numerical analysis results and the plate element heating circumference ratio results using the coefficients. Therefore, under the above conditions, it was clear that by setting the coefficients α1, α2, β1, and β2 to 1 / 10 to 1 / 3, and calculating and comparing the heating perimeter ratio of the plate elements, it is possible to predict the ranking of how easily each plate element heats up without performing numerical analysis.

[0055] <Second Example> The surface of the H-shaped steel beam 10 is covered with fire-resistant material 20 in accordance with the shape of the H-shaped steel beam 10, and the temperature change of each plate element was verified when the H-shaped steel beam, with dimensions of "H-400×200×8×13", was heated. Note that "H-400×200×8×13" refers to an H-shaped steel beam with a beam depth H of 400 mm, a flange width W of 200 mm, a web thickness tw of 8 mm, and a flange thickness tf of 13 mm. For the fire-resistant material, we used sprayed rock wool (25mm thick), which is a spray-applied fire-resistant coating material, for the verification. Verification was carried out using both numerical analysis and the evaluation method of the second embodiment (a method for calculating the heating circumference ratio of plate elements). The numerical analysis was performed for comparison with the results obtained using the evaluation method of the second embodiment.

[0056] <Numerical Analysis> In the numerical analysis (heat conduction analysis), it was assumed that the outer surface of the fire-resistant material and the underside of the floor slab were heated according to the heating curve (standard heating curve, standard heating temperature curve) specified in ISO 834-11:2014 (hereinafter, ISO 834), and the temperature change of each plate element of the H-shaped steel during a fire was analyzed.

[0057] The results of the numerical analysis are shown in the graph in Figure 7. In Figure 7, the horizontal axis represents time (seconds), and the vertical axis represents temperature (°C). By comparing the ease with which each plate element of the H-beam was heated, it was found that the susceptibility of the plate elements of the H-beam beam of the dimensions examined ("H-400×200×8×13") was web > lower flange > upper flange.

[0058] <Plate element heating circumference ratio> Next, the heating perimeter ratio of each plate element of an H-shaped steel beam was used to evaluate how easily each plate element heated up during a fire, when the surface of the H-shaped steel beam was covered with fire-resistant material in accordance with the shape of the H-shaped steel. The heating perimeter ratio of each plate element was calculated using the method described in the second embodiment.

[0059] Based on the evaluation using the heating circumference ratio of the plate element, the heating circumference ratio of the upper flange was 77(m -1 ), the heating circumference ratio of the web is 267(m -1 ), the heating circumference ratio of the lower flange is 154(m -1 ) was.

[0060] Comparing the results of the numerical analysis with the results of the plate element heating perimeter ratio, the ranking of how easily each plate element heats up was the same for both the numerical analysis results and the results of the plate element heating perimeter ratio using the calculation conditions of the second embodiment. In other words, it was clear that in an H-shaped steel beam where a fire-resistant material is coated on the surface of the H-shaped steel along the shape of the H-shaped steel, the ranking of how easily each plate element heats up can be predicted by calculating the heating perimeter and the plate element heating perimeter ratio using the calculation conditions described in the second embodiment.

[0061] As described above, the evaluation method according to this embodiment makes it possible to evaluate how easily an H-shaped steel beam heats up, regardless of conditions such as the shape of the H-shaped steel beam.

[0062] The technical scope of this disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of this disclosure. For example, in the perimeter ratio calculation step, the heated perimeter ratio of all plate elements constituting the H-beam does not need to be calculated. For example, in the perimeter ratio calculation step, the heated perimeter ratio of any plate element of the upper flange, lower flange, or web of the H-beam does not need to be calculated. In other words, in the perimeter ratio calculation step, the ease of heating of only some of the plate elements constituting the H-beam may be evaluated.

[0063] Furthermore, it is possible to replace the components in the above embodiments with well-known components as appropriate, without departing from the spirit of this disclosure.

[0064] (Note) The above embodiment can be understood, for example, as follows:

[0065] <1> An evaluation method according to one aspect of the present disclosure is an evaluation method for evaluating how easily an H-shaped steel beam, which is a beam made of H-shaped steel and covered with a fire-resistant material, heats up when heated during a fire, and includes: a heating circumference calculation step of calculating the heating circumference of each plate element according to calculation conditions; a circumference ratio calculation step of calculating the heating circumference ratio of each plate element by dividing the heating circumference of each plate element calculated in the heating circumference calculation step by the cross-sectional area of ​​each plate element; and a comparison step of comparing the heating circumference ratio of each plate element, wherein the calculation conditions in the heating circumference calculation step are that the fire-resistant material has two sides The fire-resistant material has a lower surface and a side surface of the fire-resistant material positioned opposite the web, with the upper end of the side surface of the fire-resistant material in contact with the side surface of the upper flange, the lower end of the side surface of the fire-resistant material in contact with the side surface of the lower flange, and the lower surface of the fire-resistant material in contact with the lower surface of the lower flange. The heating circumference of the upper flange is calculated using the following formula (5), the heating circumference of the web is calculated using the following formula (6), and the heating circumference of the lower flange is calculated using the following formula (7). The value of the coefficient is set according to the construction state of the fire-resistant material. H SR(UF) =L×α1+L×α2···(5) H SR(W) =2H-(L×α1+L×α2)-(L×β1+L×β2)...(6) H SR(LF) =L×β1+L×β2+W···(7) H SR(UF) : Heating circumference of the upper flange H SR(W) : Heating circumference of the web H SR(LF) : Heating circumference of the lower flange L: Flange width on one side (mm) H: Beam depth (mm) W: Flange width (mm) α1, α2, β1, β2: coefficients With this configuration, by calculating and comparing the heating perimeter ratio for each plate element of an H-shaped steel beam covered with fire-resistant material in a U-shape, the relative ease of heating for each plate element can be evaluated, allowing for individual prediction of how each plate element will heat up. Furthermore, by defining the calculation conditions for the heating perimeter and calculating it using the above formula, the performance of the H-shaped steel beam covered with fire-resistant material in a U-shape can be evaluated in more detail. In addition, evaluating the performance of the H-shaped steel beam using the heating perimeter ratio of the plate elements can reduce the cost required for analysis and evaluation of the H-shaped steel beam's performance compared to evaluations by experiment or numerical analysis. Therefore, compared to conventional evaluations using the heating perimeter ratio, the performance of the H-shaped steel beam can be evaluated in more detail while reducing the cost required for evaluation.

[0066] <2> An evaluation method according to another aspect of the present disclosure is an evaluation method for evaluating how easily an H-shaped steel beam, which is a beam made of H-shaped steel and covered with a fire-resistant material, heats up when heated during a fire, and includes: a heating circumference calculation step of calculating the heating circumference of each plate element according to calculation conditions; a circumference ratio calculation step of calculating the heating circumference ratio of each plate element by dividing the heating circumference of each plate element calculated in the heating circumference calculation step by the cross-sectional area of ​​each plate element; and a comparison step of comparing the heating circumference ratio of each plate element, wherein the calculation conditions in the heating circumference calculation step include at least one of the following: when the fire-resistant material is arranged on the surface of the H-shaped steel along the shape of the H-shaped steel, the heating circumference of the upper flange is calculated using the following formula (11), the heating circumference of the web is calculated using the following formula (12), and the heating circumference of the lower flange is calculated using the following formula (13). H SR(UF) =W···(11) H SR(W) =2H···(12) H SR(LF) =2W···(13) H SR(UF) : Heating circumference of the upper flange H SR(W) : Heating circumference of the web H SR(LF) : Heating circumference of the lower flange H: Beam depth (mm) W: Flange width (mm) With this configuration, by calculating and comparing the heating perimeter ratio for each plate element of an H-beam, where the surface of the H-beam is coated with fire-resistant material along the shape of the H-beam, the relative ease of heating for each plate element can be evaluated, and the heating of each plate element can be individually predicted. Furthermore, by defining the calculation conditions for the heating perimeter and calculating the heating perimeter using the above formula, the performance of the H-beam, where the surface of the H-beam is coated with fire-resistant material along the shape of the H-beam, can be evaluated in more detail. In addition, evaluating the performance of an H-beam using the heating perimeter ratio of plate elements can reduce the cost required for the analysis and evaluation of the H-beam's performance compared to evaluation by experiment or numerical analysis. Therefore, compared to conventional evaluation using the heating perimeter ratio, the performance of the H-beam can be evaluated in more detail, and the cost required for evaluation can be reduced.

[0067] <3> the above <1> In the evaluation method relating to this, the fire-resistant material may be a wrap-around fire-resistant coating or a box-type coating, and the coefficient may be 1 / 10 to 1 / 3. With this configuration, in an H-shaped steel beam constructed by wrapping fire-resistant material around it in a U-shape, the ease with which the plate elements heat up can be evaluated in more detail based on the heating circumference ratio of the plate elements of the H-shaped steel.

[0068] <4> the above <2> In the evaluation method relating to this, the fire-resistant material may be a spray-on fire-resistant coating material.

[0069] <5> the above <1> from <4> In any of the evaluation methods, at least one of the flange and the web may have a thickness of 3 mm to 12 mm. Conventional evaluation methods based on heating circumference ratio sometimes failed to provide detailed evaluations, particularly for H-beams with specific shapes such as thin flanges or thin webs. According to the evaluation method disclosed herein, even H-beams with thin flanges or thin webs, as described above, can be evaluated in more detail for their ease of heating. [Explanation of Symbols]

[0070] 1 H-shaped steel beam 10 H-beam 11 Web 12 flanges 12a Upper flange 12b Lower flange 20 Fireproof materials S100 Evaluation Steps S110 Cross-sectional area calculation step S120 Heating circumference calculation step S130 Circumference Ratio Calculation Step S140 Comparison Steps

Claims

1. An evaluation method for evaluating how easily an H-shaped steel beam, which is a beam made of H-shaped steel and covered with fire-resistant material, heats up when heated during a fire, A heating perimeter calculation step that calculates the heating perimeter for each plate element according to the calculation conditions, A perimeter ratio calculation step is performed by dividing the heating perimeter of each plate element calculated in the heating perimeter calculation step by the cross-sectional area of ​​each plate element to calculate the heating perimeter ratio for each plate element. A comparison step of comparing the heating circumference ratio for each plate element, Includes, The calculation conditions in the heating circumference calculation step are: When the fire-resistant material has two sides and one bottom surface, and the sides of the fire-resistant material are positioned opposite the web, and the upper end of the sides of the fire-resistant material is in contact with the side of the upper flange, and the lower end of the sides of the fire-resistant material is in contact with the side of the lower flange, and the bottom surface of the fire-resistant material is in contact with the bottom surface of the lower flange, The heating circumference of the upper flange is calculated using the following formula (5), the heating circumference of the web is calculated using the following formula (6), and the heating circumference of the lower flange is calculated using the following formula (7), including at least one of these: Depending on the installation status of the fire-resistant material, the values ​​of the coefficients included in formulas (5), (6), and (7) are set. Evaluation method. H ＳＲ（ＵＦ） =L×α1+L×α2・・・(5) H ＳＲ（Ｗ） =2H-(L×α11+L×α2)-(L×β11+L×β2)・・・(6) H ＳＲ（ＬＦ） =L×β1+L×β2+W・・・(7) H ＳＲ（ＵＦ） : Heating circumference of the upper flange H ＳＲ（Ｗ） : Heating circumference of the web H ＳＲ（ＬＦ） : Heating circumference of the lower flange L: Flange width on one side (mm) H: Beam depth (mm) W: Flange width (mm) α1, α2, β1, β2: coefficients

2. An evaluation method for evaluating how easily an H-shaped steel beam, which is a beam made of H-shaped steel and covered with fire-resistant material, heats up when heated during a fire, A heating perimeter calculation step that calculates the heating perimeter for each plate element according to the calculation conditions, A perimeter ratio calculation step is performed by dividing the heating perimeter of each plate element calculated in the heating perimeter calculation step by the cross-sectional area of ​​each plate element to calculate the heating perimeter ratio for each plate element. A comparison step to compare the heating circumference ratio for each plate element, Includes, The calculation conditions in the heating circumference calculation step are: When the fire-resistant material is arranged on the surface of the H-shaped steel beam, along the shape of the H-shaped steel beam, The heating circumference of the upper flange is calculated using the following formula (11), the heating circumference of the web is calculated using the following formula (12), and the heating circumference of the lower flange is calculated using the following formula (13), including at least one of these: Evaluation method. H ＳＲ（ＵＦ） =W・・・(11) H ＳＲ（Ｗ） =2H・・・(12) H ＳＲ（ＬＦ） =2W・・・(13) H ＳＲ（ＵＦ） : Heating circumference of the upper flange H ＳＲ（Ｗ） : Heating circumference of the web H ＳＲ（ＬＦ） : Heating circumference of the lower flange H: Beam depth (mm) W: Flange width (mm)

3. The aforementioned fire-resistant material is a wrap-around fire-resistant covering material, and is box-type. The coefficient is between 1 / 10 and 1 / 3. The evaluation method according to claim 1.

4. The aforementioned fire-resistant material is a spray-on fire-resistant coating material. The evaluation method according to claim 2.

5. At least one of the flange and the web has a thickness of 3 mm to 12 mm. The evaluation method according to any one of claims 1 to 4.

Images