Inorganic load-bearing plates and load-bearing walls

Abstract

The invention relates to an inorganic load-bearing plate of low specific gravity, lightweight and capable of ensuring non-combustibility, as well as a load-bearing wall comprising such inorganic load-bearing plate and having a high effective wall length factor. The inorganic load-bearing plate (50) comprises inorganic fiber material with a content ranging from 0.3% by weight to 6.0% by weight, and the inorganic load-bearing plate (50) has a low specific gravity, specifically a specific gravity ranging from 0.7 to 0.9. The load-bearing wall (70) comprises a frame (40) and the inorganic load-bearing plate (50) fastened to the frame (40) by fastening mechanisms (60). The frame (40) comprises vertical members (30), an upper horizontal member (21) connecting the upper ends of the vertical members (30), and a lower horizontal member (22) connecting the lower ends of the vertical members (30). The fastening mechanisms are screws.

Description

Inorganic load-bearing surfaces and load-bearing walls

[0001] The present disclosure relates to inorganic load-bearing facings and load-bearing walls.

[0002] In order for walls such as exterior walls and partition walls to have a high wall multiplier, it is necessary to increase the shear strength (or rigidity) of the bearing surface materials that form the walls. Here, bearing surface materials are mainly classified into wood-based bearing surface materials and inorganic bearing surface materials. Wood-based bearing surface materials include structural plywood, medium density fiberboard (MDF), oriented strand board (OSB), etc.

[0003] On the other hand, inorganic bearing surface materials include cement boards, calcium silicate boards, and gypsum boards (including gypsum boards). Compared to wood-based bearing surface materials, inorganic bearing surface materials have superior fire resistance, moisture permeability, and dimensional stability, and are therefore widely used in the walls of wooden buildings. Here, as stated in Ministry of Construction Notification No. 1100, nails are commonly used as fasteners to attach bearing surface materials to pillars, etc.

[0004] Therefore, in conventional wooden buildings, high-specific-gravity inorganic load-bearing surface materials (board materials) with a specific gravity of 1.0 or more are used to increase rigidity. However, high-specific-gravity inorganic load-bearing surface materials are heavy, making them difficult to handle, and they have issues such as being prone to cracking when fastened to pillars or studs.

[0005] If an attempt is made to solve this problem by using a thin inorganic load-bearing surface material, for example, one with a thickness of about 9 mm or less, then the non-combustibility of the inorganic load-bearing surface material will be reduced, and therefore simply reducing the thickness is hardly a good idea.

[0006] In addition, to achieve a high wall coefficient, the maximum strength P of the inorganic bearing surface material ｍａｘ It is not a hard bearing surface material for increasing the ultimate displacement δ ｕ High-strength face materials are advantageous.

[0007] However, for example, in the case of a gypsum board with a specific gravity of 1.0 (an example of an inorganic bearing surface material, a gypsum-based surface material in which the outer surface of a gypsum core (core material) is covered with gypsum board base paper), the maximum bearing strength P ｍａｘ It has been determined that when the deformation angle reaches 20 x 10, the gypsum core is destroyed and the remaining strength is lost. －３ After rad, the strength decreased early, 0.8P ｍａｘ The strength reduction is specified as follows: ｍａｘ The ultimate displacement of the bearing surface material is δ ｕ This refers to the strength when it reaches

[0008] Therefore, if the specific gravity of the gypsum board is reduced, the nail lateral resistance will decrease, and the maximum strength P ｍａｘ Although lowering the specific gravity of gypsum boards improves their toughness somewhat, it also reduces the strength of the gypsum board itself, leading to issues such as a decrease in rigidity and an inability to obtain sufficient strength.

[0009] The frame length of a bearing wall (the length of the wall on the architectural plan) is generally used as an indicator of the strength of a wooden building against short-term horizontal loads (earthquake force, wind pressure, etc.). A wall factor appropriate to the structure of the bearing wall is used to calculate the frame length. Here, the "wall factor" is an indicator of the earthquake resistance or strength performance of the bearing wall, and the higher the value, the greater the earthquake resistance strength.

[0010] To summarize the method for calculating the wall coefficient, in principle, the smallest value of the four types of strength values ​​(1) to (4) below is used as the short-term standard shear strength P ｏ and the short-term standard shear strength P ｏ The wall factor is the value obtained by multiplying the yield strength P by a predetermined reduction coefficient (α) (a coefficient that evaluates the factors that reduce the strength). ｙ (2) Ultimate strength P ｕ The ultimate strength correction value P is corrected based on the ductility factor μ ｕ ' (3) Maximum proof stress P ｍａｘ 2 / 3 of (4) Strength when shear deformation angle is 1 / 120 rad

[0011] In the case of wood-based bearing surface materials with high toughness, the yield strength value is often determined by the above (1), whereas in the case of inorganic bearing surface materials with low toughness, the yield strength value is often determined by the above (2). ｕ Since the ductility factor μ is small, the ultimate strength correction value P ｕ Since the strength value is determined by ' and the wall factor is determined based on this strength value, there is room for improvement in the wall factor calculated based on a low strength value.

[0012] For the above reasons, there is a demand for inorganic bearing surface materials that are low in specific gravity, lightweight, and can guarantee non-combustibility, as well as bearing walls that are equipped with this inorganic bearing surface material and have a high wall coefficient of elasticity.

[0013] Patent Document 1 proposes a wooden exterior wall structure in which a surface material is applied to the exterior side of a wooden framework or wooden frame. This wooden exterior wall structure has gypsum boards fixed as load-bearing surface materials to the exterior side of the wooden framework members or wooden frame members, the gypsum core portion of the gypsum boards contains an organopolysiloxane compound as a load-bearing surface material that prevents load-bearing deterioration, and the wall body formed by fixing the gypsum boards as load-bearing surface materials to the framework or frame has a wall multiplier of 2.0 or more as the strength of the wooden exterior wall against short-term horizontal loads.

[0014] JP 2015-165087 A

[0015] The wooden exterior wall structure described in Patent Document 1 can maintain a wall strength factor of 2.0 or more as the strength of the wooden exterior wall against short-term horizontal loads. However, it does not disclose the above-mentioned problem, i.e., an inorganic load-bearing surface material that is low in specific gravity, lightweight, and can guarantee non-combustibility.

[0016] The present disclosure provides an inorganic bearing surface material that is low in specific gravity, lightweight, and guaranteed to be non-combustible, and a bearing wall that is equipped with this inorganic bearing surface material and has a high wall ratio.

[0017] An inorganic load-bearing surface material according to one embodiment of the present disclosure is an inorganic load-bearing surface material having a low specific gravity in the range of 0.7 to 0.9, and containing inorganic fiber material in the range of 0.3 mass% to 6.0 mass%.

[0018] Furthermore, a load-bearing wall according to one aspect of the present disclosure includes: a frame including a plurality of vertical members, upper horizontal members and lower horizontal members that respectively connect the upper ends and lower ends of the vertical members; and the inorganic load-bearing face material that is fixed to the frame by a plurality of fasteners, wherein the fasteners are screws.

[0019] According to the present disclosure, it is possible to provide an inorganic load-bearing surface material that is low in specific gravity, lightweight, and guaranteed to be non-combustible, and a load-bearing wall that is equipped with this inorganic load-bearing surface material and has a high wall coefficient.

[0020] Fig. 1 is a front view of an example of a bearing wall equipped with inorganic bearing surface materials according to an embodiment. Fig. 2 is a cross-sectional view taken along the line II-II in Fig. 1, enlarging the area where the inorganic bearing surface materials are fixed to the upper horizontal member with screws. Fig. 3 is a diagram showing the envelope of the load-deformation angle curve obtained by an in-plane shear test of a wooden building, and a linear graph obtained by converting the envelope into the load-deformation angle characteristics of a perfectly elasto-plastic model.

[0021] Hereinafter, inorganic bearing surface materials and bearing walls according to embodiments will be described with reference to the accompanying drawings. Note that in this specification and drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[0022] [Inorganic Load-Bearing Face Material and Shear Wall According to an Embodiment] An example of an inorganic load-bearing face material and a shear wall according to an embodiment will be described with reference to Figures 1 and 2. Note that, while gypsum board will be used as the inorganic load-bearing face material in the following description, cement boards and calcium silicate boards may also be used as the inorganic load-bearing face material according to the embodiment. Here, Figure 1 is a front view of an example of a shear wall equipped with an inorganic load-bearing face material according to an embodiment. Figure 2 is a cross-sectional view taken along the line II-II in Figure 1 , enlarging the area where the inorganic load-bearing face material is fixed to the upper cross member with screws. Furthermore, Figure 3 shows the envelope of the load-deformation curve obtained by an in-plane shear test on a wooden building, along with a linear graph obtained by converting the envelope into the load-deformation characteristic of a perfectly elasto-plastic model.

[0023] The bearing wall 70 shown in FIG. 1 is a bearing wall of a wooden frame construction method, formed by fixing a wooden frame onto a continuous footing 10 made of reinforced concrete.

[0024] A base 22 (an example of a lower cross member) extending laterally (e.g., horizontally) is fixed on the continuous footing 10 via anchor bolts 11. Two columns 31 (an example of vertical members) and a plurality of studs 32 (another example of vertical members) (three in the illustrated example) are fixed on the base 22 and spaced a predetermined distance between them. A beam 21 (an example of an upper cross member) extending laterally (e.g., horizontally) is fixed to the upper ends of these vertical members 30. The base 22, beam 21, and the plurality of vertical members 30 form a frame 40. Here, the illustrated shear wall 70 is shown as an example formed within the structural plane of the first floor, but in shear walls formed within the structural plane of the second or higher floors, both the lower cross member and the upper cross member serve as beams for the upper floors.

[0025] The base 22, the vertical members 30, and the beams 21 are all made of wood (square timber) that is used in ordinary wooden buildings.

[0026] The inorganic load-bearing surface material 50 fastened to the frame 40 is gypsum board. Gypsum board includes structural gypsum board, reinforced gypsum board, ordinary gypsum board, etc. as specified in JIS A 6901, but it is preferable to use structural gypsum board or reinforced gypsum board as the load-bearing surface material. Gypsum board is a gypsum-based surface material in which gypsum board base paper 52 covers the front and back surfaces of a plate-shaped core material made of a gypsum core 51 (gypsum hardened body).

[0027] The applicable gypsum board 50 (short side length t1 × long side length t2 × thickness) is made of a non-combustible material and has dimensions of 910 mm × 1820 mm (2420 mm, 2730 mm) × 12.5 mm (15 mm, 21 mm, 25 mm). The width (short side) of the gypsum board is 910 mm, 606 mm, 1000 mm, 1220 mm, etc., and the length (long side) of the gypsum board is 1820 mm, 2000 mm, 3030 mm, etc. In actual construction, for example, gypsum board located at the end of a wall may be cut to size on-site. Therefore, in addition to the gypsum boards of the above dimensions, gypsum boards cut to any size are also available.

[0028] As illustrated above, the thickness of the gypsum board 50 in the illustrated example is 12 mm or more, and by applying a gypsum board 50 having a thickness of 12 mm or more, the non-combustibility of the gypsum board 50 can be ensured.

[0029] The gypsum board 50 is fastened to each vertical member 30, beam 21, and base 22 with a plurality of iron or stainless steel screws 60 (an example of a fastener).

[0030] The fastening pitch t3 of the screws 60 can be set in the range of 50 mm to 300 mm, for example, to 150 mm.

[0031] 2, the screw 60 has a head 61 that is circular in plan view, a sharp tip 62a, and a shank 62 that has a male thread on the outer periphery, and the head 61 is continuous in a curved shape from the shank 62. The screw 60 in the illustrated example is a fully threaded type in which the male thread is provided over the entire shank 62, but it may also be a half-threaded type in which the male thread is provided from midway along the shank to the tip.

[0032] The screw 60 is specified by the material and shape of the head 61 and shank 62, as well as the diameter of the head 61 (head diameter d1), the diameter of the shank 62 (shank diameter d2), and the overall length (length s2) of the screw 60. The head diameter d1 can be set to about 7 mm to 9 mm, for example, 8.2 mm, the shank diameter d2 can be set to about 3 mm to 4.5 mm, for example, 3.8 mm, and the length s2 can be set to about 25 mm to 45 mm, for example, 28 mm.

[0033] Conventionally, as mentioned above, nails have generally been used as fasteners for fastening load-bearing face materials, but in the illustrated load-bearing wall 70, screws 60 are used as fasteners. Nails that are simply hammered in to secure the gypsum board 50 require a total length of about 2.5 to 3 times the thickness s1 of the gypsum board 50, but the length s2 of the screws 60 that are screwed in to secure the gypsum board need only be about twice the thickness s1 of the gypsum board.

[0034] By using the screw 60, the male thread of the screw 60 can increase the fastening force compared to nails.

[0035] Furthermore, the area ratio of the area of ​​the head portion 61 to the cross-sectional area of ​​the shaft portion 62 is preferably set in the range of 2.0 to 3.0. By setting the area ratio in the range of 2.0 to 3.0, it is possible to achieve an ultimate displacement of the bearing wall measured in an in-plane shear test using a bearing wall specimen having a wall length of 1.82 m that is greater than 1 / 30 rad.

[0036] The gypsum core 51 of the gypsum board 50 contains a predetermined amount of inorganic fiber material and organic strength improving material, has a low specific gravity in the range of 0.7 to 0.9, and has a screw side resistance of 500 N or more, and is 5.5 N / mm ２ It has a compressive strength of at least 1000kJ / s.

[0037] Here, "low specific gravity" refers to a specific gravity that does not cause the area around the head 61 of the gypsum board 50 to bulge when the screw 60 is driven in. Furthermore, structural gypsum boards Type A and Type B specified in Ministry of Construction Notification No. 1100 are cited as typical gypsum-based load-bearing surface materials, and since the low-specific-gravity Type A has a specific gravity of around 0.8 and the high-specific-gravity Type B has a specific gravity of around 1.0, a specific gravity of around 0.8 can be said to be low.

[0038] Here, screw lateral resistance will be explained in relation to nail lateral resistance. Nail lateral resistance refers to the shear strength or shear strength of the nailed portion of a surface material, measured using the nail lateral resistance test specified in JIS A 6901. Specifically, a 150 mm x 75 mm test specimen was taken from the test surface material. A 2.6 mm diameter through-hole was drilled on the centerline of the rectangular specimen, 12 mm longitudinally (vertically) from the top edge of the specimen when viewed from the front. A steel rod (2.6 mm diameter, approximately 40 mm long) was inserted into this through-hole, and the structural plane (center plane) of the specimen was held approximately vertical. The rod was then held horizontally, and the lower end of the specimen was fixed. A load is then applied to the round bar, causing it to rise at a rate of approximately 6 mm / min. As the round bar displaces upward, the local load acting from the round bar on the through hole of the test piece causes the test piece to break, and the strength at break is measured.

[0039] In contrast to nail lateral resistance, screw lateral resistance can be determined by conducting similar tests, substituting various screws for the steel round bar used in the nail lateral resistance test. However, screws have a greater variety of geometric characteristics than nails, such as head diameter, nominal diameter, and number of threads, which are reflected in the shear strength or shear capacity. Therefore, in this study, test specimens were created using self-drilling tapping screws (JIS B 1125) with a nominal diameter of 4.2 mm and a length of 41 mm, which are commonly used to fasten gypsum board 50. Other applicable screws include other screws conforming to self-drilling tapping screws (JIS B 1125) and cross-recessed wood screws (JIS B 1112).

[0040] The amount of inorganic fiber material blended in the gypsum board 50 is in the range of 0.3% by mass to 6.0% by mass. Examples of inorganic fiber materials that can be blended include glass fiber, carbon fiber, etc. Among these, glass fiber is more suitable as an additive for industrial products because it is cheaper than carbon fiber and is widely available on the market.

[0041] When glass fibers are used, glass fibers having a diameter of 5 to 25 μm and a length of 2 to 25 mm can be suitably used.

[0042] The reason for specifying the amount of inorganic fiber material to be mixed in the range of 0.3 mass% to 6.0 mass% is that if the amount is below 0.3 mass%, the strength of the surface material, such as screw lateral resistance and compressive strength, may not be fully exhibited, and if the amount is above 6.0 mass%, sufficient strength as a surface material is already ensured, which leads to higher costs and results in over-specification.

[0043] The blending amount of the organic strength-enhancing material in the gypsum board 50 is in the range of 0.05% by mass to 4.00% by mass. Examples of the blended organic strength-enhancing material include starch, polyvinyl acetate, polyvinyl alcohol, and polyacrylic. Both unmodified and modified starch can be used as the starch. Examples of modified starch include starch that has been subjected to physical, chemical, or enzymatic treatment. Pregelatinized starch can be suitably used as the physically treated starch. Examples of chemically treated starch that can be suitably used include oxidized starch, phosphate-esterified starch, urea phosphate-esterified starch, hydroxypropylated phosphate cross-linked starch, hydroxyethylated starch, hydroxypropylated starch, cationized starch, and acetylated starch.

[0044] By setting the blending amount of the organic strength improving material in the range of 0.05% by mass to 4.00% by mass, a low specific gravity of 0.7 to 0.9 is ensured while achieving a specific gravity of 5.5 N / mm ２ The above compressive strength can be imparted to the gypsum board 50.

[0045] The organic strength improving material is an effective material that cooperates with the inorganic fiber to achieve a screw side resistance of 500 N or more in the gypsum board 50. Furthermore, considering that the blending of the organic strength improving material does not significantly affect the overall quality of the gypsum-based load-bearing surface material other than the screw side resistance, it is a preferable material for improving the screw side resistance of the gypsum board 50.

[0046] The low specific gravity of the gypsum board 50, 0.7 to 0.9, allows for weight reduction and improves workability. Furthermore, the low specific gravity of the gypsum board 50 allows for weight reduction while ensuring non-combustibility by setting the thickness to 12 mm or more. However, using a gypsum board with a thickness of approximately 9 mm in an attempt to reduce the weight of the gypsum board is undesirable because it becomes difficult to ensure non-combustibility.

[0047] Here, the non-combustibility of the gypsum board 50 is measured by a cone calorimeter test, which is one of the evaluation methods for non-combustible materials in the Building Standards Act, and the total heat generation amount in a heating time of 20 minutes is 8 MJ / m ２ The inventors have identified the following and have demonstrated that the material is non-combustible:

[0048] Furthermore, in the bearing wall 70, screws 60 are used as fasteners to fasten the gypsum board 50. However, if the specific gravity of the gypsum board is high, such as 1.0 or more, a portion of the gypsum core may bulge around the screw when the screw is screwed in, causing a problem of insufficient screw threading. In contrast, the gypsum board 50 in the illustrated example has a low specific gravity of 0.7 to 0.9, so even when screws 60 are used as fasteners, the gypsum board 50 can be firmly fixed to the frame 40 without swelling.

[0049] While the low specific gravity of the gypsum board 50 provides the various effects described above, the wall ratio of the shear wall generally tends to decrease. However, the gypsum board 50 contains inorganic fiber material in a blending amount ranging from 0.3% to 6.0% by mass, contains organic strength improving material in a blending amount ranging from 0.05% to 4.00% by mass, and further uses screws 60 instead of nails as fasteners, so the ultimate strength correction value P ｕ A bearing wall 70 having a strength ' of 8.0 kN or more can be formed.

[0050] Here, the wall magnification will be described with reference to Fig. 3. The perfectly elastoplastic model shown in Fig. 3 is a linear function line in the linear elastic region (elastic region) and a yield point σ ｓThe line of the plastic deformation region (plastic region) extends parallel to the X-axis from the yield point σ ｓ indicates the elastic limit. The method of converting the envelope curve into a perfect elasto-plastic model is a well-known method described in documents such as "Wooden Shear Wall and Its Magnification Performance Testing and Evaluation Manual."

[0051] In Figure 3, the maximum strength P ｍａｘ , 0.8P ｍａｘ Load reduction area, ultimate strength P ｕ , yield strength P ｙ , ultimate displacement δ ｕ , yield point displacement δ ｖ , and yield displacement δ ｙ is shown. The ultimate displacement δ ｕ and yield point displacement δ ｖ are 0.8P respectively. ｍａｘ Load drop region and yield point σ ｓ is the shear deformation angle at ｙ is the yield strength P ｙ The shear deformation angle at the time of occurrence is the plasticity factor μ. ｕ / δ ｖ is the value.

[0052] As described in the literature such as "Allowable Stress Design of Wooden Frame Construction Houses [1] (2017 Edition)" on pages 63 and 300, the strength P specified by the perfect elastic-plastic model shown in Figure 3 is ｍａｘ , P ｕ , P ｙ , and displacement δ ｕ , δ ｖ , δy, the short-term allowable shear strength P ａ Calculate the short-term allowable shear strength P ａ The wall ratio is calculated by dividing by a predetermined strength (wall length L (m) × 1.96 (kN / m)).

[0053] In calculating the wall coefficient, the smallest value of the four types of strength values ​​(1) to (4) below is used as the short-term standard shear strength P ｏ and the short-term standard shear strength P ｏ The value obtained by multiplying the specified reduction coefficient (α) (coefficient for evaluating the factors that reduce the strength) is the short-term allowable shear strength P ａHere, the ultimate strength correction value P ｕ ' is 0.2P ｕ / Ds=0.2P ｕ × (2μ-1) １／２ The structural characteristic coefficient Ds is calculated as follows: Ds = 1 / (2μ-1) １／２ (1) Yield strength P ｙ (2) Ultimate strength P ｕ The ultimate strength correction value P is corrected based on the ductility factor μ ｕ ' (3) Maximum proof stress P ｍａｘ (4) Strength when the shear deformation angle is 1 / 120 rad (unloaded or loaded)

[0054] In the case of wood-based bearing surface materials with high toughness, the bearing strength value is often determined by the above (1), whereas in the case of gypsum board 50 with low toughness, the bearing strength value is often determined by the above (2). ｕ Since the ductility factor μ is small, the ultimate strength correction value P ｕ Since the strength value is determined by ' and the wall factor is determined based on this strength value, there is room for improvement in the wall factor.

[0055] In this regard, the gypsum board 50 has a low specific gravity and contains an inorganic fiber material and / or an organic strength-improving material, which increases toughness and contributes to increasing the wall modulus.

[0056] Furthermore, by using screws 60 instead of nails as fasteners for fastening the gypsum board 50 to the frame 40, the force for fastening the gypsum board 50 to the frame 40 is improved, making it less likely that damage will occur due to punching out in the fastening area, and toughness is increased, which also contributes to increasing the wall coefficient.

[0057] Furthermore, since the area ratio of the area of ​​the head 61 of the screw 60 to the cross-sectional area of ​​the shank 62 is in the range of 2.0 to 3.0, an ultimate displacement δu of greater than 1 / 30 rad can be achieved as the ultimate displacement of the shear wall measured by an in-plane shear test using a shear wall specimen with a wall length of 1.82 m, and the strength value can be increased as described above in (2), which also contributes to increasing the wall factor.

[0058] It should be noted that other embodiments may be possible in which other components are combined with the configurations described in the above embodiments, and the present disclosure is not limited to the configurations shown here. In this regard, modifications are possible within the scope of the present disclosure, and can be appropriately determined depending on the application form.

[0059] This international application claims priority based on Japanese Patent Application No. 2023-179477, filed on October 18, 2023, the entire contents of which are incorporated herein by reference.

[0060] 10: Continuous footing 11: Anchor bolt 21: Beam (upper horizontal member) 22: Base (lower horizontal member) 30: Vertical member 31: Pillar (vertical member) 32: Stud (vertical member) 40: Frame 50: Bearing surface material (inorganic bearing surface material, gypsum board) 51: Gypsum core 52: Base paper for gypsum board 60: Screw (fastener) 61: Head 62: Shank 62a: Tip 70: Bearing wall

Claims

1. An inorganic load-bearing surface material having a low specific gravity in the range of 0.7 to 0.9 and containing inorganic fiber material in the range of 0.3% by mass to 6.0% by mass.

2. The inorganic load-bearing surface material according to claim 1, wherein the organic strength improving material is contained in an amount ranging from 0.05% by mass to 4.00% by mass.

3. The inorganic load-bearing surface material according to claim 2, having a thickness of 12 mm or more.

4. The inorganic load-bearing surface material according to claim 3, wherein the inorganic fiber material is a glass fiber material.

5. The total heat release in 20 minutes measured by the cone calorimeter test is 8 MJ / m ２ 5. The inorganic load-bearing surface material according to claim 4, characterized in that:

6. The inorganic load-bearing surface material according to claim 5, having a screw side resistance of 500 N or more.

7. 5.5N / mm ２ 7. The inorganic load-bearing surface material according to claim 6, having a compressive strength of at least 100%.

8. The inorganic load-bearing surface material according to claim 7, wherein the load-bearing surface material is formed from gypsum board.

9. A load-bearing wall comprising: a frame having a plurality of vertical members and upper horizontal members and lower horizontal members respectively connecting the upper ends and lower ends of the vertical members; and an inorganic load-bearing surface material according to any one of claims 1 to 8 which is fixed to the frame by a plurality of fasteners, wherein the fasteners are screws.

10. Among the physical properties of bearing walls measured by in-plane shear tests, the ultimate strength P ｕ The ultimate strength correction value P is corrected based on the ductility factor μ ｕ 10. The load-bearing wall according to claim 9, wherein ' is 8 kN or more.

11. A load-bearing wall as claimed in claim 10, wherein the screw has a head and a shank, the area ratio of the head area to the cross-sectional area of ​​the shank is in the range of 2.0 to 3.0, and the ultimate displacement of the load-bearing wall measured by an in-plane shear test using a load-bearing wall specimen having a wall length of 1.82 m has an ultimate displacement δu of greater than 1 / 30 rad.

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