Inorganic bearing surface material and bearing wall

Abstract

Provided is an inorganic load-bearing board in which the ultimate strength correction value is increased to the extent possible by increasing the plasticity, and thus the co-efficient of effective wall length can be increased; and a load-bearing wall including this inorganic load-bearing board. An inorganic load-bearing board 50, in which a board width in a front view of the load-bearing board 50 is less than 910 mm. Preferably, a load-bearing strength value applied for calculation of a co-efficient of effective wall length of the load-bearing board is determined by an ultimate strength correction value obtained by correcting an ultimate strength of the load-bearing board based on plasticity, among four types of load-bearing strength values below: (1) yield strength Py; (2) ultimate strength correction value Pu', obtained by correcting ultimate strength Pu based on plasticity µ (where µ = δu / δv, and δu is an ultimate displacement and δv is a yield point displacement); (3) 2 / 3 of maximum load-bearing strength Pmax; and (4) a load-bearing strength at an apparent shear deformation angle of 1 / 120 rad or a load-bearing strength at a true shear deformation angle of 1 / 300 rad.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to inorganic load-bearing boards and load-bearing walls.BACKGROUND ART

[0002] In order for a wall, such as an external wall, a partition wall, or the like, to have a high co-efficient of effective wall length, it is necessary to increase the shear strength (or rigidity) of the load-bearing boards forming the wall. The load-bearing boards are mainly classified into wooden load-bearing boards and inorganic load-bearing boards. The wooden load-bearing boards include structural plywood, medium density fiberboards (MDF), oriented strand boards (OSB), and the like. The inorganic load-bearing boards include cement boards, calcium silicate boards, and gypsum boards (including gypsum plates). Compared to wooden load-bearing boards, inorganic load-bearing boards are excellent in fire resistance, moisture permeability, and dimensional stability, and thus are widely applied in the walls of wooden buildings.

[0003] Therefore, for existing wooden buildings, inorganic load-bearing boards (board materials) with a high specific gravity of 1.0 or higher are applied in order to increase rigidity thereof. However, such inorganic load-bearing boards with a high specific gravity are heavy in weight and thus are poor in handling performance. Thus, in an attempt to fasten the inorganic load-bearing boards by driving fasteners, such as nails or the like, into columns and studs, the inorganic load-bearing boards are likely to crack.

[0004] Load-bearing boards with long residual strength (the ultimate displacement δ u is large) like wooden load-bearing boards are advantageous over hard load-bearing boards for increasing the maximum load-bearing strength P max of inorganic load-bearing boards in terms of achieving a high co-efficient of effective wall length. However, for example, in the case of a gypsum board with a specific gravity of 1.0 (an example of the inorganic load-bearing boards, and a gypsum-based board including gypsum board base paper covering the outer surface of a gypsum core (core material)), it is found that the residual strength disappears once the gypsum core has been destroyed at the time of reaching the maximum load-bearing strength P max . For example, it is found that the strength decreases at an early stage after the deformation angle reaches 20×10 -3< rad, and the strength decreases to be 0.8P max or lower. Here, "0.8P max " refers to a load-bearing strength at the time the load-bearing board reaches the ultimate displacement δ u .

[0005] It is also found that as the specific gravity of the gypsum board is reduced, the lateral nail resistance is reduced, and the maximum load-bearing strength P max is reduced. Here, the "lateral nail resistance" refers to a shear load-bearing strength or shear strength of a nail-driven portion of the load-bearing board as measured by the lateral nail resistance test as stipulated in JIS A 6901. The toughness of a gypsum board is slightly increased by reducing the specific gravity of the gypsum board. However, the strength of the gypsum board itself is reduced. This leads to reduction in the rigidity thereof, and sufficient load-bearing strength cannot be obtained.

[0006] The board width of a typical inorganic load-bearing board is 910 mm or more, and more specifically is in the range of from 910 mm through 1,820 mm. Such a typical inorganic load-bearing board with a typical board width generally has high rigidity but has low toughness, and as a result is likely to have low load-bearing strength as a load-bearing board. In the present specification, the "board width" means the length of a short side in a front view, and "low toughness" means a shear deformation angle at which the ultimate displacement δ u is from about 30×10 -3< rad through about 35×10 -3< rad.

[0007] As an index of the strength of wooden buildings to resist short-term horizontal loads (seismic force, wind pressure, and the like), the framework length of load-bearing walls (the length of walls in a plan diagram of a building) is typically used. For the calculation of the framework length, a co-efficient of effective wall length corresponding to the structure of the load-bearing wall is used. Here, the "co-efficient of effective wall length" refers to an index of seismic resistance or load-bearing strength of the load-bearing wall, and the higher the value thereof, the greater the seismic resistance.

[0008] A calculation method of the co-efficient of effective wall length will be outlined. In principle, the load-bearing strength value having the smallest value among the following four types of load-bearing strength values (1) to (4) is specified as a short-term reference shear strength P o , and the co-efficient of effective wall length is a value obtained by multiplying the short-term reference shear strength P o by a predetermined reduction co-efficient (α) (a co-efficient for evaluating the factor of the reduction in the load-bearing strength): (1) yield strength P y ; (2) ultimate strength correction value P u ', obtained by correcting ultimate strength P u based on plasticity µ; (3) 2 / 3 of maximum load-bearing strength P max ; and (4) load-bearing strength at a shear deformation angle of 1 / 120 rad.

[0009] The load-bearing strength value of wooden load-bearing boards with high toughness is often determined in accordance with (1) above. Meanwhile, the load-bearing strength value of inorganic load-bearing boards with low toughness is often determined in accordance with (2) above. That is, in inorganic load-bearing boards having a typical board width of 910 mm or more as described above, the ultimate strength P u is low and the plasticity µ is low, and thus the load-bearing strength value thereof is determined in accordance with the ultimate strength correction value P u '. The co-efficient of effective wall length is determined in accordance with the determined load-bearing strength value, and thus there is room for improvement in the co-efficient of effective wall length calculated in accordance with the low load-bearing strength value.

[0010] Therefore, regarding such inorganic load-bearing boards, it is desired to provide an inorganic load-bearing board in which the ultimate strength correction value P u ' is increased to the extent possible by increasing the plasticity µ, and thus the co-efficient of effective wall length can be increased.

[0011] Patent Document 1 proposes a wooden exterior wall structure having a structure in which boards are applied to the outdoor side surface of a wooden frame or a wooden framework. The wooden exterior wall structure includes gypsum plates fixed as load-bearing boards on the outdoor side surface of a wooden frame member or a wooden framework member. A gypsum core of the gypsum plate contains an organopolysiloxane compound as a load-bearing strength deterioration inhibitor that prevents deterioration in the load-bearing strength. A wall body obtained by fixing the gypsum plate to the frame or framework as a load-bearing board has a co-efficient of effective wall length of 2.0 or higher as the strength of a wooden exterior wall that resists short-term horizontal loads.RELATED ART DOCUMENTPATENT DOCUMENTS

[0012] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-165087SUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0013] According to the wooden exterior wall structure described in Patent Document 1, a co-efficient of effective wall length of 2.0 or higher can be ensured as the strength of the wooden exterior wall that resists the short-term horizontal loads. However, Patent Document 1 does not disclose the above-described issue, i.e., a method that can increase the co-efficient of effective wall length of an inorganic load-bearing board by increasing the plasticity to increase the ultimate strength correction value to the extent possible.

[0014] The present disclosure provides: an inorganic load-bearing board in which the ultimate strength correction value is increased to the extent possible by increasing the plasticity, and thus the co-efficient of effective wall length can be increased; and a load-bearing wall including this inorganic load-bearing board.MEANS FOR SOLVING THE PROBLEMS

[0015] An inorganic load-bearing board according to one aspect of the present disclosure is such that a board width in a front view of the load-bearing board is less than 910 mm.

[0016] Also, an inorganic load-bearing board according to another aspect of the present disclosure is such that a load-bearing strength value applied for calculation of a co-efficient of effective wall length of the inorganic load-bearing board is determined by an ultimate strength correction value obtained by correcting an ultimate strength of the inorganic load-bearing board based on plasticity, among four types of load-bearing strength values below: (1) yield strength P y ; (2) ultimate strength correction value P u ', obtained by correcting ultimate strength P u based on plasticity µ (where µ = δ u / δ v , and δ u is an ultimate displacement and δ v is a yield point displacement); (3) 2 / 3 of maximum load-bearing strength P max ; and (4) a load-bearing strength at an apparent shear deformation angle of 1 / 120 rad or a load-bearing strength at a true shear deformation angle of 1 / 300 rad. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0017] According to the present disclosure, it is possible to provide: an inorganic load-bearing board in which the ultimate strength correction value is increased to the extent possible by increasing the plasticity, and thus the co-efficient of effective wall length can be increased; and a load-bearing wall including this inorganic load-bearing board.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [FIG. 1] FIG. 1 is a front view of an example of a load-bearing wall including an inorganic load-bearing board according to an embodiment. [FIG. 2] FIG. 2 is a diagram illustrating an envelope of a load vs. deformation angle curve obtained by an in-plane shear testing of a wooden building, and a linear graph obtained by converting the envelope to load vs. deformation angle characteristics of a total elastic-plastic model. EMBODIMENTS OF THE INVENTION

[0019] Hereinafter, an inorganic load-bearing board and a load-bearing wall according to the embodiment will be described with reference to the accompanying drawings. In the present specification and the drawings, substantially the same components may be designated by the same reference numerals, and duplicate description thereof may be omitted.[Inorganic load-bearing board and load-bearing wall according to the embodiment]

[0020] Examples of the inorganic load-bearing board and the load-bearing wall according to the embodiment will be described with reference to FIGS. 1 and 2. In the following, a gypsum board is described as the inorganic load-bearing board. However, a cement plate or a calcium silicate plate may be applied to the inorganic load-bearing board according to the embodiment. FIG. 1 is a front view of an example of the load-bearing wall including the inorganic load-bearing board according to the embodiment. Also, FIG. 2 is a diagram illustrating the envelope of the load vs. deformation angle curve obtained by the in-plane shear testing of the wooden building, and the linear graph obtained by converting the envelope to load vs. deformation angle characteristics of the total elastic-plastic model.

[0021] A load-bearing wall 70 as illustrated in FIG. 1 is a load-bearing wall of a wooden framework construction method, formed by fixing a wooden framework on a footing foundation 10 formed of reinforced concrete.

[0022] On the footing foundation 10, a base 22 (an example of a lower transverse material) extending in a transversal direction (e.g., a horizontal direction) is fixed via anchor bolts 11. On the base 22, two columns 31 (an example of a vertical material) and multiple (three in the illustrated example) studs 32 (another example of the vertical material) arranged therebetween at predetermined intervals are fixed. A beam 21 (an example of an upper transverse material) extending in a transversal direction (e.g., a horizontal direction) is fixed to the upper end of these multiple vertical materials 30. Then, a frame 40 is formed by the base 22, the beam 21, and the multiple vertical materials 30. The load-bearing wall 70 in the illustrated example is illustrated as an example in which it is formed in a construction plane on the first floor. However, in the load-bearing wall formed in construction planes on upper floors, i.e., the second floor or higher, both of the lower transverse material and the upper transverse material become beams of the upper floors.

[0023] All of the base 22, the vertical material 30, and the beam 21 are formed of wood (square timber) applied in typical wooden buildings.

[0024] An inorganic load-bearing board 50 fastened to the frame 40 is a gypsum board. The gypsum board includes structural gypsum boards, reinforced gypsum boards, typical gypsum boards, and the like, stipulated in JIS A 6901. However, structural gypsum boards, reinforced gypsum boards, and the like are preferably applied as the load-bearing board. The gypsum board is a gypsum-based board in which base paper for gypsum boards is coated on the front and back surfaces of a plate-like core material formed of a gypsum core (gypsum hardened body).

[0025] Dimensions of the gypsum board 50 to be applied are as follows: a board width t1 is 600 mm, and a board height t2 is about 2,800 mm (in the range of from about 2,730 mm through about 3,030 mm). The thickness of the gypsum board 50 is 9.5 mm or 12.5 mm.

[0026] That is, the board width t1 of the gypsum board 50 is set to be in a range that is narrower than a typical range of from 910 mm through 1,820 mm. The multiple gypsum boards 50 in the illustrated example have the same board width t1. However, for example, all of the three or more gypsum boards may have different board widths. Alternatively, there may be multiple gypsum boards having the same board width and other gypsum boards having board widths different from the above same board width.

[0027] Here, as a width of less than 910 mm, the board width t1 may be set to 225 mm, 250 mm, 300 mm, 455 mm, 500 mm, 800 mm, or the like, besides 600 mm.

[0028] The gypsum board 50 is fastened to each of the vertical materials 30 with multiple nails 60 (an example of the fasteners). Here, for example, a plated iron round nail (NZ nail: JIS A 5508) is applicable as the nails 60, and the NZ50 nail (50 mm in length, about 6.6 mm in head diameter, and 2.75 mm in rod diameter) may be applicable. Here, the fastener 60 may be a screw (including a screwed screw) or the like, besides the nail.

[0029] A pitch of fastening t3 of the nails 60 can be set to be in a range of from 50 mm through 300 mm, e.g., 150 mm.

[0030] The load-bearing wall 70 is formed by fastening, to the frame 40, two pieces of the gypsum board 50 having the same board width t1. However, three or more pieces of the gypsum board 50 may be fastened, or multiple pieces of gypsum board having different board widths may be fastened.

[0031] Because the board width t1 of the gypsum board 50 forming the load-bearing wall 70 is set to be less than 910 mm, the toughness of the gypsum board 50 and the load-bearing wall 70 is increased, and the co-efficient of effective wall length of the load-bearing wall 70 can be increased. Hereinafter, a reason for this will be described in detail with reference to FIG. 2.

[0032] FIG. 2 is a diagram illustrating the envelope of the load vs. deformation angle curve obtained by the in-plane shear testing of the wooden building, and the linear graph obtained by converting the envelope to load vs. deformation angle characteristics of the total elastic-plastic model.

[0033] The total elastic-plastic model is formed of: a linear-function straight line in the linear elastic range (elastic range) and a straight line in the plastic deformation range (plastic range) extending from the yield point σ s parallel to an X axis. The yield point σ s indicates an elastic limit. A method for converting the envelope to the total elastic-plastic model is a publicly known method as described in documents, such as "Performance Test and Evaluation Methodology for Wooden load-bearing walls and Their Co-efficient of effective wall length" and the like.

[0034] FIG. 2 illustrates the maximum load-bearing strength P max , a 0.8P max post-peak region, the ultimate strength P u , the yield strength P y , the ultimate displacement δ u , the yield point displacement δ v , and the yield displacement δ y . The ultimate displacement δ u is the shear deformation angle at the 0.8P max post-peak region, and the yield point displacement δ v is the shear deformation angle at the yield point σ s . The yield displacement δ y is the shear deformation angle at the onset of the yield strength P y . The plasticity µ is the value of δ u / δ v .

[0035] The co-efficient of effective wall length is the value obtained by calculating a short-term allowable shear strength P a based on the load-bearing strengths P max , P u , and P y , and the displacements δ u , δ v , and δ y specified by the total elastic-plastic model as illustrated in FIG. 2, and dividing the short-term allowable shear strength P a by a predetermined load-bearing strength (wall length L (m)×1.96 (kN / m)) as described in documents, such as "Allowable Stress Design for Wooden Framework Construction Method Housing [1] (2017 edition)", pages 63 and 300, and the like.

[0036] For the calculation of the co-efficient of effective wall length, in principle, the load-bearing strength value having the smallest value among the following four types of load-bearing strength values (1) to (4) is specified as a short-term reference shear strength P o , and the short-term reference shear strength P o is multiplied by a predetermined reduction co-efficient (α) (a co-efficient for evaluating the factor of the reduction in the load-bearing strength), and the obtained value is defined as the short-term allowable shear strength P a . Here, the ultimate strength correction value P u ' is calculated by 0.2 P u / Ds = 0.2 P u ×(2µ-1) 1 / 2< , and the structural co-efficient Ds is 1 / (2µ-1) 1 / 2< . (1) Yield strength P y , (2) Ultimate strength correction value P u ', obtained by correcting ultimate strength P u based on plasticity µ, (3) 2 / 3 of maximum load-bearing strength P max , and (4) Load-bearing strength upon specific deformation, i.e., load-bearing strength at an apparent shear deformation angle of 1 / 120 rad (for non-loading type or loading type).

[0037] Note in all test pieces that when the yield displacement δ y of the test pieces is smaller than the true shear deformation angle of 1 / 300 rad and there is no significant damage at a true shear deformation angle of 1 / 300 rad, the load-bearing strength upon specific deformation in (4) above is not the load-bearing strength at an apparent shear deformation angle of 1 / 120 rad, but the load-bearing strength at a true shear deformation angle of 1 / 300 rad. Then, the load-bearing strength value having the smallest value among the three types of load-bearing strength values (2) to (4) is specified as the short-term reference shear strength P o .

[0038] The load-bearing strength value of wooden load-bearing boards with high toughness is often determined in accordance with (1) above. Meanwhile, the load-bearing strength value of the gypsum board 50 with low toughness is often determined in accordance with (2) above. That is, in the existing gypsum boards having a typical board width of 910 mm or more, the ultimate strength P u is low and the plasticity µ is low, and thus the load-bearing strength value thereof is determined in accordance with the ultimate strength correction value P u '. The co-efficient of effective wall length is determined in accordance with the determined load-bearing strength value, and thus there is room for improvement in the co-efficient of effective wall length.

[0039] In view of the above, the present inventors conducted extensive studies, and as a result have followed an approach based on re-consideration of the dimensions of the gypsum board rather than an approach based on material development of the gypsum boards, and have increased the toughness of the gypsum boards, increased the ultimate strength correction value P u ' that is the load-bearing strength value to be applied for the calculation of the co-efficient of effective wall length, and been able to increase the co-efficient of effective wall length.

[0040] That is, by setting the range of the board width t1 of the gypsum board 50 to be in the range of less than 910 mm rather than the typical range of from 910 mm through 1,820 mm, it is possible to increase the toughness of the gypsum board 50 and the load-bearing wall 70 including this gypsum board, and increase the co-efficient of effective wall length. Details of the in-plane shear testing will be described below, but it is demonstrated that the ultimate displacement δ u of a typical gypsum board is a shear deformation angle of from about 30×10 -3< rad through about 35×10 -3< rad, whereas the ultimate displacement δ u of the illustrated gypsum board 50 is a shear deformation angle of 40×10 -3< rad or higher and the toughness thereof is increased.

[0041] More specifically, it is demonstrated that the ultimate displacement δ u of the gypsum board 50 has a maximum shear deformation angle of 66.7×10 -3< rad, and the toughness of the gypsum board 50 becomes approximately twice as high as that of a typical gypsum board.

[0042] Also, it is demonstrated that a ratio of the co-efficient of effective wall length of the load-bearing wall 70 including the gypsum board 50 having multiple board widths of less than 910 mm (225 mm, 300 mm, 455 mm, 600 mm, 800 mm, and 847 mm) to the co-efficient of effective wall length, serving as a reference, of an existing load-bearing wall including a gypsum board (ratio thereof to the existing load-bearing wall in terms of the co-efficient of effective wall length) is in the range of from 1.16 through 1.98, and the co-efficient of effective wall length of the load-bearing wall 70 is 3.0 or higher.[In-plane shear testing and results thereof]

[0043] The present inventors produced test pieces of a load-bearing wall in accordance with the test specifications of non-loading type or loading type (test piece, testing device, and testing method) described in "Performance Test and Evaluation Methodology for Wooden load-bearing walls and Their Co-efficient of effective wall length". A comparative example is a load-bearing wall having a wall width of 1,820 mm and including two glass fiber-containing gypsum boards that are each 910 mm in the board width and 2,730 mm in height.

[0044] The test piece includes a frame formed by a cedar base having a cross section of 105 mm x 105 mm and two columns, studs having a cross section of 45 mm x 105 mm between the two columns, and Douglas fir beams having a cross section of 180 mm x 105 mm and supported by the columns. As a jig for testing, hold-down hardware is provided at the joints between the base and the columns, and at the joints between the beams and the columns.

[0045] Here, for comparison with the comparative example, a test piece of Referential Example 1 was produced. This test piece included two particle boards (each being 910 mm in the board width) applied to the load-bearing wall, instead of the gypsum boards. Referential Example 1 has the same specifications as those of the comparative example except for the material of the load-bearing board.

[0046] Meanwhile, the examples have the same specifications as those of the comparative example except for applied glass fiber-containing gypsum boards. The board widths of the glass fiber-containing gypsum boards of Examples 1 to 6 are 225 mm, 300 mm, 455 mm, 600 mm, 800 mm, and 847 mm. In Example 4, three gypsum boards were used to produce a load-bearing wall having a wall width of 1,820 mm, which was experimented. Also, in the other examples, the measured values of the comparative example and Examples 4 and 6 were used for linear interpolation, thereby obtaining calculation results. In addition, a test piece of Referential Example 2 was produced and experimented. This test piece included two particle boards each being 600 mm in the board width (a configuration in which one of the particle boards is in the width direction and the two particle boards are connected in the vertical direction).

[0047] Table 1 shows the experimental results and the calculation results. Here, regarding the ratio between the co-efficients of effective wall length, the respective ratios in Examples 1 to 6 are calculated relative to the co-efficient of effective wall length of the comparative example, and the ratio in Referential Example 2 is calculated relative to the co-efficient of effective wall length of Referential Example 1. Also, Table 2 shows five types of load-bearing strength values in the comparative example, Examples 4 and 6, and Referential Examples 1 and 2.

[0048] [Table 1]Comparative ExampleReferential Example 1Referential Example 2Example 1Example 2Example 3Example 4Example 5Example 6Load-bearing boardInorganicWoodenWoodenInorganicInorganicInorganicInorganicInorganicInorganicBoard width (mm)910910600225300455600800847Specific gravity (-)0.800.760.760.800.800.800.800.800.80Thickness (mm)9.768.988.959.759.759.759.759.759.77Test results Calculation resultsδ u (10 -3< rad)35.6466.4365.6766.6766.6766.6763.6846.0742.67δ v (10 -3< rad)6.4811.3817.0622.4520.6116.8113.488.616.25Load-bearing value determining itemPu'PyPu'Pu'Pu'Pu'Pu'Pu'Pu'Ratio of coefficient of effective wall length--0.961.981.871.661.451.191.16

[0049] [Table 2]Inorganic load-bearing boardWooden load-bearing boardComparative Example (kN / m)Example 4 (kN / m)Example 6 (kN / m)Referential Example 1 (kN / m)Referential Example 2 (kN / m)Py6.769.906.959.6810.60Pu' (0.2 Pu / Ds)6.118.987.1710.159.282 / 3Pmax7.4811.338.0011.2413.42P(1 / 120 rad)9.019.689.6110.399.53P(11300 rad)7.18-7.64--

[0050] According to Tables 1 and 2, the load-bearing strength value of Referential Example 1, including the particle boards (wooden load-bearing boards), is determined by the yield strength P y because the toughness of the load-bearing board and the load-bearing wall is high. The load-bearing strength value of Referential Example 2, in which the board width is smaller, is determined by the ultimate strength correction value P u '. It is demonstrated that a great difference does not occur between the co-efficients of effective wall length of Referential Examples 1 and 2 although the load-bearing determining item is changed by changing the board width.

[0051] Meanwhile, the load-bearing strength values of the comparative example and Examples 1 to 6, each including the glass fiber-containing gypsum boards, are determined by the ultimate strength correction value P u ' because the toughness thereof is lower than that of the wooden load-bearing boards. It is demonstrated that the ratios of the co-efficients of effective wall length of the examples to the co-efficient of effective wall length of the comparative example (the co-efficient of effective wall length of the reference inorganic bearing board having the reference board width of 910 mm) are 1.16 times through 1.98 times higher.

[0052] In Example 6 in Table 2, the value of the yield strength P y is lower than the ultimate strength correction value P u '. However, the load-bearing strength value of Example 6 in Table 1 is determined by the ultimate strength correction value P u '. The reason for this is as follows. Specifically, the standard of an evaluation method in a designated performance evaluation organization describes that when the yield displacement δ y of a test piece is smaller than the true shear deformation angle of 1 / 300 rad and there is no significant damage at the true shear deformation angle of 1 / 300 rad, the load-bearing strength at a shear deformation angle of 1 / 120 rad shall be the load-bearing strength at the true shear deformation angle of 1 / 300 rad regardless of the testing method. This also describes that the short-term reference shear strength P o is determined by one of the following three types of load-bearing strength values, i.e., the ultimate strength correction value P u ', 2 / 3 of maximum load-bearing strength P max , and the load-bearing strength at the true shear deformation angle of 1 / 300 rad. Both of the comparative example and Example 6 in Table 2 fall within a case in which the yield displacement δ y of a test piece is smaller than the true shear deformation angle of 1 / 300 rad and there is no significant damage at the true shear deformation angle of 1 / 300 rad. Thus, the load-bearing strength is determined by the smallest value among (2) the ultimate strength correction value P u ', obtained by correcting ultimate strength P u based on plasticity µ, (3) 2 / 3 of maximum load-bearing strength P max , and (4) the load-bearing strength at the true shear deformation angle of 1 / 300 rad. That is, the experimental results of Example 6 conform to this standard, and the short-term reference shear strength P o is determined by the ultimate strength correction value P u '.

[0053] Also, it is demonstrated that deformation performance (ultimate displacement δ u ) is increased to 66.7×10 -3< rad at most, compared to 35.64×10 -3< rad in the comparative example.

[0054] That is, the toughness of the glass fiber-containing gypsum board is increased by reducing the board width thereof, and the load-bearing strength value is still determined by the ultimate strength correction value P u '. However, the co-efficient of effective wall length is increased in accordance with an increase in the ultimate strength correction value P u '.

[0055] Here, the co-efficient of effective wall length of the comparative example was calculated to be about 2.7. Thus, it is demonstrated that by multiplying this value with the ratio of the co-efficient of effective wall length of each example, the co-efficient of effective wall length of each example becomes 3.0 or higher.

[0056] From the above, it is demonstrated that by narrowing the board width of a gypsum board compared to the existing board width, the toughness of the gypsum board and the load-bearing wall including the gypsum board is increased, and the co-efficient of effective wall length thereof is increased.

[0057] Other embodiments made by combining other components with the configurations as described in the above embodiments are possible. The present disclosure is not limited to the configurations described herein in any way. In this regard, it is possible to change the present disclosure without deviating from the intent of the present disclosure, and the other embodiments can be appropriately determined in accordance with forms of application.

[0058] The present international application claims priority to Japanese Patent Application No. 2022-118776 filed on July 26, 2022, and the entire contents of this application are incorporated in the present international application by reference.REFERENCE SIGNS LIST

[0059] 10: Footing foundation 11: Anchor bolt 21: Beam (upper transverse material) 22: Base (lower transverse material) 30: Vertical material 31: Column (vertical material) 32: Stud (vertical material) 40: Frame 50: Load-bearing board (inorganic load-bearing board, gypsum board) 60: Nail (fastener) 70: Load-bearing wall

Claims

1. An inorganic load-bearing board, wherein a board width in a front view of the load-bearing board is less than 910 mm.

2. The inorganic load-bearing board according to claim 1, wherein a load-bearing strength value applied for calculation of a co-efficient of effective wall length of the load-bearing board is determined by an ultimate strength correction value obtained by correcting an ultimate strength of the load-bearing board based on plasticity, among four types of load-bearing strength values below: (1) yield strength Py; (2) ultimate strength correction value Pu', obtained by correcting ultimate strength Pu based on plasticity µ (where µ = δu / δv, and δu is an ultimate displacement and δv is a yield point displacement); (3) 2 / 3 of maximum load-bearing strength Pmax; and (4) a load-bearing strength at an apparent shear deformation angle of 1 / 120 rad or a load-bearing strength at a true shear deformation angle of 1 / 300 rad.

3. The inorganic load-bearing board according to claim 1 or 2, wherein an upper value of an ultimate displacement δu regarding a shear deformation angle is 66.7×10-3 rad.

4. The inorganic load-bearing board according to any one of claims 1 to 3, wherein a ratio of a co-efficient of effective wall length of the inorganic load-bearing board to a co-efficient of effective wall length of a reference inorganic load-bearing board having a reference board width of 910 mm in the front view is in a range of from 1.16 through 1.98.

5. The inorganic load-bearing board according to any one of claims 1 to 4, wherein a co-efficient of effective wall length is 3.0 or higher.

6. The inorganic load-bearing board according to any one of claims 1 to 5, wherein the board width is 225 mm, 300 mm, 455 mm, 600 mm, 800 mm, or 847 mm.

7. The inorganic load-bearing board according to any one of claims 1 to 6, wherein the inorganic load-bearing board is formed of a gypsum board.

8. A load-bearing wall, comprising: a frame including multiple vertical materials, and an upper transverse material that connects upper ends of the multiple vertical materials to each other, and a lower transverse material that connects lower ends of the multiple vertical materials to each other; and the inorganic load-bearing board of any one of claims 1 to 7 that is fixed to the frame with multiple fasteners.

9. The load-bearing wall according to claim 8, wherein multiple load-bearing boards, each being the inorganic load-bearing board, have the same board width.

10. The load-bearing wall according to claim 8, wherein multiple load-bearing boards, each being the inorganic load-bearing board, include load-bearing boards having the same board width and load-bearing boards having different board widths.

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