JP2017002523A - Fitting structure for outer covering material made of extrusion molding cement plate, and extrusion molding cement plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fitting structure for an outer covering material made of an extrusion molding cement plate that maintains high durability even when a part of the extrusion molding cement plate is damaged, along with the extrusion molding cement plate.SOLUTION: A fitting structure 20 for an outer covering material made of an extrusion molding cement plate includes: an extrusion molding cement plate 22 having a plurality of hollow parts 21 lined up next to each other in one direction and a groove 25 extending almost linearly along the hollow part 21 formed on a surface 22h; a finishing material 23 installed on an outer surface 22g of the extrusion molding cement plate 22; and fitting means 24 that forms a damaged part 22a in the groove 25 for fixing the finishing material 23 on the outer surface 22g of the extrusion molding cement plate 22. A position of the damaged part 22a for fitting the finishing material 23 on the extrusion molding cement plate 22 is within a range corresponding to the hollow part 21 on a groove bottom 25a inside the groove 25.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a mounting structure for mounting an exterior member or equipment / pipe on the surface of an extruded cement board attached to a building frame, and to an extruded cement board, and more particularly to perforation of an extruded cement board. The present invention relates to a mounting structure capable of preventing a decrease in strength due to stress concentration on a defective portion caused by the above, and an extruded cement board.

  Extruded cement boards are widely used as building exterior materials because they are lightweight and have high strength. In the outer wall structure using an extruded cement board, generally, the angle that becomes the base material is fixed to the building frame, and the Z-clip etc. fastened to the back of the extruded cement board is locked to the angle, and the extrusion molding is performed. A cement board is attached.

  Attach finishing materials that are surface decoration materials such as tiles and stones to the surface of the extruded cement board, or provide a through hole that penetrates the front and back of the extruded cement board, and use it as a ventilation port or piping port Has been done. When attaching a finishing material to the surface of an extrusion-molded cement board, it is necessary to open a bolt hole or a screw hole in the extrusion-molded cement board, and a defective portion is generated in the extrusion-molded cement board. When a ventilating port or a piping port is provided in the extruded cement board, these become defective portions of the extruded cement board.

  For example, in Patent Document 1, a concave portion is formed in the surface portion of an extruded cement board, a reinforcing metal fitting is disposed on the back of the concave portion, and the reinforcing metal fitting is fixed to the fastener via an anchor bolt in the concave portion. The finishing material is attached by fitting the dowel pin provided in the hole into the hole provided in the end surface of the finishing material.

Japanese Utility Model Publication No. 63-51039

  When a finishing material is attached to the surface as in Patent Document 1 or there is a defect portion due to the formation of a ventilation port or the like, when tensile stress acts on the outside of the extruded cement plate and bending deformation occurs, Stress concentrates on the missing part. When stress concentrates on the defect portion, the bending strength of the extruded cement board is reduced by about 30% compared to the case where the defect portion does not exist, and there is a possibility that the fracture occurs with a force smaller than the inherent bending strength. . Therefore, the allowable stress level is designed to be lower than the original stress level. Designing with a lower allowable stress level will lead to a smaller support span for the extruded cement board. For example, when installing in a high-rise building with a vertical floor, there will be a problem that the support span is insufficient between the beams. It was.

  Therefore, in view of the problems of the prior art, the present invention provides a structure for mounting an exterior member of an extruded cement board capable of maintaining the high strength of the extruded cement board even if a defect portion exists in the extruded cement board, and the extrusion molding. The purpose is to provide a cement board.

  The extrusion-molded cement board exterior member mounting structure according to the present invention includes an extrusion-molded cement in which a plurality of hollow portions are arranged in parallel in one direction and a groove portion extending substantially linearly along the hollow portion is formed on the surface portion. A plate, an exterior member installed on the surface of the extruded cement plate, and an attachment means for forming a defective portion on the surface portion of the extruded cement plate and fixing the exterior member to the surface, The defect portion is formed in a range corresponding to the hollow portion in the groove bottom in the groove portion.

  According to the exterior member mounting structure for an extruded cement plate of the present invention, a groove portion extending substantially linearly along the hollow portion is formed on the surface portion of the extruded cement plate, and the defect portion is inside the groove portion for attaching the exterior member. Since it is formed within a range corresponding to the hollow portion at the bottom of the groove, the strength does not decrease due to the stress concentration on the defective portion. Therefore, it can design without reducing the allowable stress level of the extrusion-molded cement board, and can maintain a high proof stress. As a result, it is not necessary to reduce the support span of the extruded cement board, and the degree of freedom in the construction of the extruded cement board can be maintained.

  It is preferable that the thickness of the extruded cement board corresponding to the groove is 40 to 100 mm. If the thickness of the extruded cement board corresponding to the groove is 40 to 100 mm, the high strength of the extruded cement board can be maintained.

  It is preferable that W1> W2 is satisfied when the width excluding the groove portion is W1 and the width of the groove portion is W2 in the entire width of the extruded cement board. When the width of the extruded cement plate excluding the groove portion exceeds the width of the groove portion, the superiority to the extruded cement plate without the groove portion can be maintained.

  When A is the distance from the centroid of the extruded cement plate to the groove bottom of the groove, and B is the distance from the centroid to the surface of the extruded cement plate, A / B = 0.4 to 0.7 It is preferable to satisfy. In this case, strength reduction due to stress concentration on the defect portion can be reliably prevented.

  Examples of the exterior member include a finishing material installed on the surface of the extruded cement board, a wall decoration material or a signboard installed in the groove of the extruded cement board.

  The extruded cement board of the present invention is an extruded cement board having a plurality of hollow portions arranged in parallel in one direction and having a through-hole for passing equipment or piping passing through the front and back, and the hollow portion on the surface portion. A groove portion extending substantially linearly is formed along the through hole, and the through hole is formed in the groove portion.

  If the extruded cement board of the present invention is used, a groove portion extending substantially linearly along the hollow portion is formed in the surface portion of the extruded cement board, and the through hole is formed in the groove portion. The strength does not decrease due to the stress concentration. Therefore, it can design without reducing the allowable stress level of the extrusion-molded cement board, and can maintain a high proof stress. As a result, it is not necessary to reduce the support span of the extruded cement board, and the degree of freedom in the construction of the extruded cement board can be maintained.

  In the extruded cement plate, the thickness of the extruded cement plate corresponding to the groove is preferably 40 to 100 mm. If the thickness of the extruded cement board corresponding to the groove is 40 to 100 mm, the high strength of the extruded cement board can be maintained.

  It is preferable that W1> W2 is satisfied when the width excluding the groove portion is W1 and the width of the groove portion is W2 in the entire width of the extruded cement board. When the width of the extruded cement plate excluding the groove portion exceeds the width of the groove portion, the superiority to the extruded cement plate without the groove portion can be maintained.

  When A is the distance from the centroid of the extruded cement plate to the groove bottom of the groove, and B is the distance from the centroid to the surface of the extruded cement plate, A / B = 0.4 to 0.7 It is preferable to satisfy. In this case, it is possible to reliably prevent the strength from being reduced due to the stress concentration in the through hole.

  You may form the said groove part in both the front side and back side of an extrusion-molded cement board. In this case, the high yield strength of the extruded cement board can be reliably maintained.

  According to the present invention, since the strength is not reduced due to stress concentration in the defect portion or the through hole, the design can be performed without lowering the allowable stress level, and high proof stress can be maintained. As a result, it is not necessary to reduce the support span of the extruded cement board, and the degree of freedom in the construction of the extruded cement board can be maintained.

It is sectional drawing which shows the extrusion-molded cement board which concerns on 1st Embodiment of this invention. FIG. 2 is an end view, a plan view, and a side view of the extruded cement board of FIG. 1. It is explanatory drawing for demonstrating the relationship between the distance from a centroid, and a stress degree. It is sectional drawing which shows the extrusion-molded cement board which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the extrusion molding cement board which concerns on 3rd Embodiment of this invention. It is sectional drawing and the principal part enlarged view which show the exterior member attachment structure of the extrusion-molded cement board which concerns on 1st Embodiment of this invention. It is sectional drawing and the front view which show the exterior member attachment structure of the extrusion-molded cement board which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the conventional extrusion molding cement board. FIG. 9 is an end view, a plan view, and a side view of the extruded cement board of FIG. 8.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an extruded cement board 1 according to a first embodiment of the present invention, and FIG. 2 is an end view, a plan view, and a side view of the extruded cement board 1 of FIG. The extrusion-molded cement board 1 is an exterior material that is attached to a building frame by a vertical stretching method or a horizontal stretching method. The extrusion-molded cement board 1 is manufactured by extruding a mixture obtained by kneading water, cement, aggregates, fibers, and the like with an extruder, curing and curing, and cutting to a predetermined size. In the extruded cement board 1, a plurality of hollow portions 2 having a rectangular cross section are formed in parallel to each other in the longitudinal direction that is the extrusion direction. The plurality of hollow portions 2 are configured to form a plurality of partition walls 3 that connect the surface-side base material 1a and the back-side base material 1b of the extruded cement board 1. In the following description, the upper side of the extrusion-molded cement board 1 in the figure is the outside in the state of being attached to the building, and the lower side is the inside of the state of being attached.

  In the outer wall structure using the extrusion-molded cement board 1, an angle as a base material is generally fixed to a housing of a building, and a Z clip or the like fastened to the back surface of the extrusion-molded cement board 1 is locked to the angle. An extruded cement board 1 is attached.

  In the extrusion-molded cement board 1 of the present embodiment, a through hole 4 having a circular shape in plan view that penetrates the front and back is formed in the center in the width direction. The through-hole 4 serves as a ventilation port or a piping port for passing equipment or piping that penetrates the front and back surfaces, and the diameter D is formed so that Wm> D. Although the through hole 4 of the present embodiment is circular in plan view, it may have other shapes. On the outer surface portion 1 h of the extruded cement board 1, one groove portion 5 extending in a substantially linear shape along the hollow portion 2 is formed. As shown in FIG. 1, the groove portion 5 has left and right side ends 5b and 5b inclined inward toward the groove bottom 5a, and is formed in an inverted trapezoidal shape in cross section. In the present embodiment, the number of the groove portions 5 is one, but a plurality of groove portions may be formed on the surface portion 1 h of the extruded cement board 1.

  As shown in FIGS. 1 and 2, the through hole 4 is formed in a substantially central portion in the width direction in the groove portion 5. The through hole 4 is accommodated in the groove portion 5, and therefore the diameter D of the through hole 4 is smaller than the groove bottom width Wm of the groove portion 5. The thickness S1 of the extruded cement board 1 to which this embodiment is applied is about 50 to 120 mm, and the thickness S2 of the extruded cement board 1 corresponding to the groove 5 is 40 to 100 mm.

  When bending deformation due to an external force occurs in the extruded cement board 1, the degree of stress increases as the part is farther from the centroid N. Here, the centroid means the centroid position in the thickness direction of the extruded cement board 1. Accordingly, when the extruded cement plate 1 having the groove portion 5 provided in the surface portion 1h as in the present embodiment is subjected to bending deformation so that the outer side with the groove portion 5 becomes a tensile stress, the groove bottom in the extruded cement plate 1 is provided. A surface portion 1ha that is not 5a (hereinafter referred to as an outer surface portion) is a portion that generates the maximum stress. The groove bottom 5a is a portion that produces a lower stress level than the outer surface portion 1ha.

  Therefore, the fracture starts from the outer surface portion 1ha of the extruded cement board 1, and the strength of the extruded cement board 1 is determined on the basis of the properties of the outer surface portion 1ha. Even when a through hole that may cause strength reduction is provided in the extruded cement board, if the through hole 4 exists in the groove portion 5 as in the present embodiment, the outer surface portion 1ha of the extruded cement board 1 is obtained. The generated stress can be borne. As a result, it is possible to prevent a decrease in strength due to stress concentration in the through hole 4. This effect is particularly effective when bending deformation due to tensile stress occurs on the surface of the extruded cement board on which the groove is formed.

As described above, the outer surface portion 1ha of the extrusion-molded cement board 1 is a portion that generates the maximum stress. If the ratio of the groove part 5 in the surface part 1h increases, the cross-section coefficient value when there is no through-hole will become small, and the predominance with respect to the extrusion-molded cement board which does not provide a groove part will reduce. Therefore, the following formula is satisfied when the width of the outer surface portion 1ha excluding the groove portion 5 is W1 and the width of the groove portion 5 is W2 in the entire width W of the extruded cement board 1.
W1> W2
The width W1 of the outer surface portion 1ha excluding the groove portion 5 is the sum of the widths of the portions divided into a plurality of portions by the groove portion 5 as shown in FIG. The width W2 when a plurality of groove portions are formed is the sum of the widths of all the groove portions. In the present embodiment, as shown in FIG. 1, there are two inclined portions 6 that are inclined obliquely at both left and right ends of the extruded cement board 1. The sum of the widths W2 of all the grooves includes the widths of all the portions recessed inward from the outer surface 1g of the extruded cement board 1 as described above.

  The difference in the degree of stress between the outer surface portion 1ha of the extruded cement board 1 and the groove bottom 5a corresponds to the ratio of the distance from the centroid N of the extruded cement board 1 with reference to the explanatory view of FIG. I found out. The relationship between the stress levels is: (distance from centroid N to groove bottom) / (distance from centroid N to outer surface) = (degree of bending stress generated at groove bottom) / (bending stress generated at outer surface portion) Degree). Therefore, the bending stress degree of the extruded cement board 1 can be calculated based on the cross-sectional shape of the extruded cement board 1, its dimensions, and the centroid N.

When the distance from the centroid N of the extruded cement plate 1 to the groove bottom 5a is A and the distance from the centroid N to the outer surface 1g is B, the following formula is satisfied.
A / B = 0.4-0.7
A / B = about 0.7 is a boundary point for avoiding stress concentration in the through-hole 4, and by setting A / B = 0.4 to 0.7, the stress concentration in the through-hole 4 is a factor. It is possible to reliably prevent the strength from being reduced. If A / B is 0.7 or less, the stress in the groove portion 5 is 70% or less of the outermost surface and stress concentration does not occur. However, if A / B is 0.7 or more, stress concentration cannot be avoided. However, if it is 0.4 or less, the remaining thickness of the groove portion 5 becomes thin, which may affect the strength in the width direction.

  When a through-hole is formed in a conventional extruded cement board, the strength is reduced by about 30% due to the stress concentration in the through-hole, but the groove portion 5 has a stress that is 30% or more smaller than that of the surface portion 1h of the extruded cement board 1. By forming the through hole 4 in the inside, it is possible to prevent the strength reduction of the extruded cement board 1 due to the influence of stress concentration.

  If it is set as the extrusion-molded cement board 1 of this embodiment, the groove part 5 extended substantially linearly along the hollow part 2 will be formed in the surface part 1h of the extrusion-molded cement board 1, and the through-hole 4 which penetrates front and back will be formed. Since it is formed in the groove 5, the strength is not reduced due to the stress concentration in the through hole 4. Therefore, it can design without reducing the allowable stress degree of the extrusion-molded cement board 1, and can maintain a high yield strength. Thereby, it is not necessary to make the support span of the extrusion-molded cement board 1 small, and the freedom of construction of the extrusion-molded cement board 1 can be maintained.

  Since the thickness S2 of the extrusion-molded cement plate 1 corresponding to the groove portion 5 is 40 to 100 mm, the high strength of the extrusion-molded cement plate 1 can be maintained. Out of the entire width W of the extruded cement plate 1, the width W1 of the outer surface portion 1ha excluding the groove portion 5 exceeds the width W2 of the groove portion, so that the superiority to the extruded cement plate without the groove portion can be maintained. .

  Since the distance A from the centroid N of the extruded cement board 1 to the groove bottom 5a and the distance B from the centroid N to the outer surface 1g satisfy A / B = 0.4 to 0.7, it penetrates. It is possible to reliably prevent the strength from being reduced due to the stress concentration in the hole 4.

  Conventionally, in order to increase the support span of an extruded cement board, the thickness of the extruded cement board has been increased. For this reason, the cross section becomes large, and the cost is increased due to an increase in the burden on the work site due to an increase in weight. In the extrusion-molded cement board 1 of this embodiment, since high intensity | strength is maintained without increasing thickness, a weight does not increase and it does not cause a cost increase.

  Examples of the present invention will be described. The present invention is not limited to this embodiment. The limit load of the conventional extrusion-molded cement board 40 (with a through-hole) as a comparative example shown in FIGS. 8 and 9 and the extrusion-molded cement board 1 (with a through-hole) of the above-described embodiment as an example is calculated. Both the extruded cement board 40 of the comparative example and the extruded cement board 1 of the example have a thickness S1: 80 mm, an overall width W: 590 mm, a length L (support span) 2000 mm, a diameter D of the through holes 4 and 41: 100 mm, and through The holes 4 and 41 were positioned at the center between the supports.

When the support span of the extruded cement board is L, the strength of the extruded cement board is σ, the section modulus of the effective section is Z, and the load K acts on the center of the support span L of the extruded cement board, the bending stress From the calculation formula, the limit load P is expressed by the following formula.
P × L / (4 × Z) ≦ σ × 0.7
(0.7 is a reduction rate considering the effect of stress concentration due to cross-sectional defects)
P ≦ (σ × 0.7 × 4 × Z) / L

(Comparative example)
The limit load P1 of the comparative example is calculated. The cross-sectional area before forming the through hole, the cross-sectional modulus Z of the effective cross-sectional portion, and the strength σ of the extruded cement board are as follows.
Cross-sectional area before forming the through hole: 241 cm ²
Section modulus Z of effective section portion: 416 cm ³
Strength of extruded cement board σ: 17.6 N / mm ²

P1 ≦ (σ × 0.7 × 4 × Z) / L
P1 ≦ (17.6 × 0.7 × 4 × 416000) / 2000
P1 ≦ 10250N

(Example)
The limit load P2 of the embodiment is calculated. The cross-sectional area before forming the through hole, the cross-sectional modulus Z of the effective cross-sectional portion, and the strength σ of the extruded cement board are as follows.
Cross-sectional area before forming the through hole: 237 cm ²
Section modulus Z of effective section portion: 350 cm ³
Strength of extruded cement board σ: 17.6 N / mm ²

P2 ≦ (σ × 4 × Z) / L
P2 ≦ (17.6 × 4 × 350,000) / 2000
P2 ≦ 12320N

  From the calculation results, it is recognized that the example in which the through hole 4 is formed in the groove part 5 has a limit load P2 that is about 1.2 times the limit load P1 of the comparative example without the groove part. That is, the critical load can be increased by about 1.2 times without increasing the thickness and increasing the cross-sectional area. Thereby, even if the through-hole 4 exists, the support span L of the extrusion-molded cement board 1 can be maintained without increasing the thickness.

  FIG. 4 is a cross-sectional view showing an extruded cement board 10 according to the second embodiment of the present invention. This embodiment is different from the first embodiment in that the groove is formed on both the front side and the back side of the extruded cement board 10. A first groove 11 that is the same groove as in the first embodiment is formed on the outer surface portion 1 h of the extruded cement board 10, and the first groove 11 is also formed on the inner surface portion 1 h of the extruded cement board 10. A second groove 12 having the same shape and the same size is formed. The configuration other than the point where the second groove portion 12 is formed is the same as that of the first embodiment, and the same reference numerals are given to the common configurations. According to the extrusion-molded cement board 10 of this embodiment, the strength of the front and back of the extrusion-molded cement board 10 can be reliably maintained.

  FIG. 5 is a cross-sectional view showing an extruded cement board 15 according to the third embodiment of the present invention. In the present embodiment, a through hole 17 larger than that in the first embodiment is formed in the groove 16. The side end of the groove part 16 is formed along the thickness direction, and the groove part 16 has a rectangular shape in cross section. Main components other than the groove part 16 and the through-hole 17 are common to 1st Embodiment, and attaches | subjects the same code | symbol to each common structure. Even when a larger through-hole 17 is formed in the extruded cement board 15, the strength does not decrease due to the stress concentration in the through-hole 17. Therefore, it can design without reducing the allowable stress degree of the extrusion-molded cement board 15, and can maintain a high yield strength. Regarding the relationship between the dimension of the groove 16 and the dimension of the through hole 17, when the width of the groove 16 is Wm and the diameter of the through hole 17 is D, the relationship of Wm> D is satisfied. It can be surely prevented.

  FIG. 6 is a cross-sectional view showing an exterior member mounting structure 20 for an extruded cement board according to the first embodiment of the present invention. The extruded cement board exterior member mounting structure 20 of the present embodiment includes an extruded cement board 22 in which a plurality of hollow portions 21 are arranged in one direction, and an outer surface (surface) 22 g of the extruded cement board 22. A finishing material 23, which is an installed exterior member, and attachment means 24 for fixing the finishing material 23 to the outer surface 22g of the extruded cement board 22 are provided.

  The finishing material 23 is fixed to the outer surface 22g of the extruded cement board 22 with an adhesive. Two grooves 25 having a rectangular cross section extending substantially linearly along the hollow portion 21 are formed on the outer surface portion 22 h of the extruded cement board 22. One end of a drop-off preventing iron wire 27 is fixed in each groove portion 25 by a tapping screw 26, and a deficient portion 22 a by the tapping screw 26 is formed on the groove bottom 25 a of each groove portion 25. The other end of the fall-off prevention iron wire 27 is fixed to the back surface of the finishing material 23. Thus, the finishing material 23 is fixed to the extrusion cement board 22 by forming the defect | deletion part 22a in the groove bottom 25a of the extrusion molding cement board 22. FIG. If the finishing material can be fixed, the number of grooves and attachment means is not limited. Further, the position of the defect portion 22 a is within a range corresponding to the hollow portion 21 in the groove bottom 25 a in the groove portion 25. As a result, it is possible to make it more difficult for stress to concentrate on the defect 22a.

  In the extrusion cement board 22 used for the exterior member mounting structure 20 of the extrusion cement board, the same effect as the extrusion cement board 1 of the first embodiment can be obtained. This point will be described.

  The thickness S1 of the extruded cement plate 22 to which this embodiment is applied is about 50 to 120 mm, and the thickness S2 of the extruded cement plate 22 corresponding to the groove 25 is 40 to 100 mm. When bending deformation due to an external force occurs in the extruded cement board 1, the degree of stress increases as the part is farther from the centroid N. Accordingly, when the extruded cement plate 22 provided with a plurality of grooves 25 in the surface portion 22h as in this embodiment is subjected to bending deformation so that the outer side with the grooves 25 becomes tensile stress, the outer surface portion 22ha is the maximum. It becomes the part which produces the degree of stress. On the other hand, the groove bottom 25a is a portion that produces a lower stress level than the outer surface portion 22ha.

  For this reason, the fracture starts from the outer surface portion 22ha of the extruded cement plate 22, and the strength of the extruded cement plate 22 is determined based on the properties of the outer surface portion 22ha. Even when a defect portion 22a that causes a decrease in strength is formed on the extruded cement plate 22, if the defect portion 22a is present in the groove 25 as in the present embodiment, the extruded cement plate 22 The generated surface stress can be applied to the outer surface portion 22ha. As a result, it is possible to prevent a decrease in strength due to stress concentration on the defect 22a. In particular, since the defect portion 22a is formed in a range corresponding to the hollow portion 21 in the groove bottom 25a in the groove portion 25, stress concentration on the defect portion 22a can be reliably prevented. These effects are particularly effective when bending deformation due to tensile stress occurs on the surface of the extruded cement board on which the groove is formed.

As described above, the outer surface portion 22ha of the extruded cement board 22 is a portion that generates the maximum stress. If the ratio of the groove part 25 in the surface part 22h increases, a section modulus value will become small and the predominance with respect to the extrusion-molded cement board which does not provide a groove part will reduce. Therefore, the following formula is satisfied when the width of the outer surface portion 22ha excluding the groove portion 25 is W1 and the width of the groove portion 25 is W2 in the entire width W of the extruded cement board 22.
W1> W2
The width W1 of the outer surface portion 22ha excluding the groove portion 25 is the total width of the portions divided into a plurality of portions by the groove portion 25 as shown in FIG. The width W2 of the groove portion is the sum of the widths of all the groove portions, and in the case of this embodiment, is the sum of the widths of the two groove portions 25.

  It has been found that the difference in the degree of stress between the outer surface portion 22ha of the extruded cement plate 22 and the groove bottom 25a corresponds to the ratio of the distance from the centroid N of the extruded cement plate 22. The relationship between the stress levels is: (distance from centroid N to groove bottom) / (distance from centroid N to outer surface) = (degree of bending stress generated at groove bottom) / (bending stress generated at outer surface portion) Degree). Accordingly, the bending stress degree of the extruded cement plate 22 can be calculated based on the cross-sectional shape of the extruded cement plate 22, its dimensions, and the centroid N.

When the distance from the centroid N of the extruded cement plate 22 to the groove bottom 25a is A and the distance from the centroid N to the outer surface 22g is B, the following equation is satisfied.
A / B = 0.4-0.7
A / B = 0.7 is a boundary point for avoiding stress concentration on the defect portion 22a. By setting A / B = 0.4 to 0.7, stress concentration on the defect portion 22a is a factor. It is possible to reliably prevent the strength from being reduced.

  When a defect portion such as a tapping screw is formed on a conventional extruded cement board, the strength is reduced by about 30% due to the stress concentration on the defect portion, but the stress is reduced in the groove portion 25 by 30% or less than the surface portion 22h. By forming the defect portion 22a, it is possible to prevent the extrusion cement board 22 from being broken due to the stress concentration.

  If it is set as the exterior member attachment structure 20 of the extrusion-molded cement board of this embodiment, the several groove part 25 extended substantially linearly along the hollow part 21 will be formed in the surface part 22h of the extrusion-molding cement board 22, and finishing. Since the defect portion 22a is formed in a range corresponding to the hollow portion 21 in the groove bottom 25a in the groove portion 25 in order to attach the material 23, the strength is not reduced due to the stress concentration on the defect portion 22a. Therefore, it can design without reducing the allowable stress degree of the extrusion-molded cement board 22, and can maintain a high proof stress. Thereby, it is not necessary to make the support span of the extrusion-molded cement board 22 small, and the freedom of construction of the extrusion-molded cement board 22 can be maintained.

  Since the thickness S2 of the extruded cement plate 22 corresponding to the groove portion 25 is 40 to 100 mm, the high strength of the extruded cement plate 22 can be maintained. Out of the total width W of the extruded cement plate 22, the width W1 of the outer surface portion 22ha excluding the plurality of groove portions 25 exceeds the width W2 of the plurality of groove portions 25, so that it has an advantage over the extruded cement plate without the groove portions. Can keep.

  Since the distance A from the centroid N of the extruded cement plate 22 to the groove bottom 25a and the distance B from the centroid N to the outer surface 22g satisfy A / B = 0.4 to 0.7, It is possible to reliably prevent the strength from being reduced due to the stress concentration on the portion 22a.

  Conventionally, in order to increase the support span of an extruded cement board, the thickness of the extruded cement board has been increased. For this reason, the cross section becomes large, and the cost is increased due to an increase in the burden on the work site due to an increase in weight. In the extrusion-molded cement board 22 of this embodiment, since high intensity | strength is maintained without increasing thickness, a weight does not increase and it does not cause a cost increase.

  FIG. 7 is a sectional view and a front view showing an exterior member mounting structure 30 for an extruded cement board according to a second embodiment of the present invention. The groove part 32 of the extrusion-molded cement board 31 of this embodiment is formed wide. The signboard 33 which is an exterior member is fixed in the groove portion 32 of the extrusion-molded cement board 31 by mounting means 35 including a plurality of mounting bolts 34 and the like. In the groove bottom 32 a of the groove portion 32, a plurality of missing portions 31 a that are bolt holes of the mounting bolt 34 are formed. The defect portion 31 a is formed in a range corresponding to the hollow portion in the groove bottom 32 a in the groove portion 32.

  Even when the signboard 33 as an exterior member is attached in the groove portion 32, the defect portion 31 a is formed in the groove portion 32, and the position of the defect portion 31 a corresponds to the hollow portion in the groove bottom 32 a in the groove portion 32. By making it inside, the strength does not decrease due to the stress concentration on the defect portion 31a. Accordingly, it is possible to design without lowering the allowable stress level of the extrusion-molded cement board 31 and to maintain a high proof stress. Thereby, it is not necessary to make the support span of the extrusion-molded cement board 31 small, and the freedom of construction of the extrusion-molded cement board 31 can be maintained.

  The present invention is not limited to the embodiments and examples. These embodiments and examples are illustrative of the extruded cement board according to the present invention and the exterior member mounting structure of the extruded cement board, and are not restrictive. The structure for attaching the extruded cement board to the casing, which is the application target of the extruded cement board according to the present invention and the exterior member attaching structure of the extruded cement board, is not limited. The number and shape of the groove portions, the number and shape of the through holes, the shape of the defective portion due to the attaching means, and the like are not limited. The kind of exterior member is not limited, For example, an exterior member is good also as a wall surface decoration material. You may use combining said embodiment. Various members such as a square nut and a clip for attaching the extruded cement plate may be provided in any form as long as the effects of the present invention are not impaired.

DESCRIPTION OF SYMBOLS 1, 10, 15 Extrusion-molded cement board 1h Surface part 1ha Outer surface part 1g Outer surface 2, 21 Hollow part 3 Partition part 4, 17 Through-hole 5, 16 Groove part 5a Groove bottom 5b Side end 6 Inclined part 11 1st groove part 12 1st 2 Groove parts 20, 30 Extruded cement board exterior member mounting structure 22, 31 Extruded cement board 22h Surface part 22ha Outer surface part 22g Outer surface 22a Defect part 23 Finishing material 24, 35 Mounting means 25, 32 Groove part 25a Groove bottom 25b Side end 26 Tapping screw 27 Fallout prevention iron wire 33 Signboard 34 Mounting bolt 40 Conventional extrusion cement plate 41 Through hole D Diameter of through hole Wm Groove bottom width W Full width W1 Width of outer surface portion W2 Groove bottom width S1 Extruded cement Thickness of the plate S2 Thickness of the extrusion-molded cement plate corresponding to the groove N centroid A Distance from the centroid to the groove bottom Figure sincerely distance K load to the outer surface

Claims (10)

A plurality of hollow portions are juxtaposed in one direction, and an extruded cement board in which a groove portion extending in a substantially linear shape along the hollow portion is formed on the surface portion;
An exterior member installed on the surface of the extruded cement plate,
An attachment means for forming a defective portion on the surface portion of the extruded cement plate and fixing the exterior member to the surface;
An exterior member mounting structure for an extrusion-molded cement board, wherein the defective portion is formed in a range corresponding to the hollow portion in the groove bottom in the groove portion.   The exterior member mounting structure for an extruded cement board according to claim 1, wherein the thickness of the extruded cement board corresponding to the groove is 40 to 100 mm. 3. The extruded cement according to claim 1, wherein, of the total width of the extruded cement plate, a width excluding the groove is W1, and the width of the groove is W2, and the following formula is satisfied. Plate exterior member mounting structure.
W1> W2 The following formula is satisfied, where A is a distance from the centroid of the extruded cement plate to the groove bottom of the groove, and B is a distance from the centroid to the surface of the extruded cement plate. The exterior member attachment structure of the extrusion-molded cement board in any one of -3.
A / B = 0.4-0.7   5. The exterior member is a finishing material installed on the surface of the extruded cement board, or a wall decoration material or a signboard installed in the groove of the extruded cement board. The exterior member attachment structure of the extrusion-molded cement board in any one of. In the extruded cement plate having a plurality of hollow portions arranged in parallel in one direction, and having a through hole for passing equipment or piping through the front and back,
An extruded cement board, wherein a groove portion extending substantially linearly along the hollow portion is formed on a surface portion, and the through hole is formed in the groove portion.   The extruded cement board according to claim 6, wherein the thickness of the extruded cement board corresponding to the groove is 40 to 100 mm. 8. The extruded cement according to claim 6 or 7, wherein, of the total width of the extruded cement plate, the width excluding the groove is W1, and the width of the groove is W2, and the following formula is satisfied. Board.
W1> W2 The following formula is satisfied, where A is a distance from the centroid of the extruded cement plate to the groove bottom of the groove, and B is a distance from the centroid to the surface of the extruded cement plate. Extruded cement board in any one of -8.
A / B = 0.4-0.7   The extruded cement board according to any one of claims 6 to 9, wherein the groove is formed on both the front side and the back side of the extruded cement board.

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