WO2023200004A1

WO2023200004A1 - Structural base material, structural member, structure, and construction method for structural member

Info

Publication number: WO2023200004A1
Application number: PCT/JP2023/015181
Authority: WO
Inventors: 順平五十嵐; 翔子五十嵐; 友洋五十嵐; 航平小川
Original assignee: 株式会社I-deate&eng.
Priority date: 2022-04-15
Filing date: 2023-04-14
Publication date: 2023-10-19
Also published as: JP2023157642A; JP7393816B2

Abstract

Provided is a structural base material with which it is possible to construct a structural member having a simple configuration not requiring shear reinforcement inside of a compression member. Also provided are the structural member, a structure, and a construction method for the structural member. This structural base material (1) is disposed inside of a compression member (11) that bears a compressive force acting on a structural member (10). The structural base material (1) is integrated with the compression member (11) when the compression member (11) has hardened, and comprises: a main body (2) formed from a material that can bear the compressive force; a tension member (3) located inside of the main body (2) so as to extend from one end of the main body (2) to the other end, and having continuous fibers that can bear a tensile force; and a plurality of support parts (4) wound around the outer circumferential surface of the tension member (3) and provided along the tension member (3), with spaces therebetween, inside of the main body (2). The tension member (3) and the support parts (4) are fixed inside of the main body (2) such that strain occurring in the tension member (3) and the support parts (4) is transmitted to the main body (2).

Description

Structural base material, structural member, structure, and construction method of structural member

The present invention relates to a structural base material, a structural member, a structure, and a method for constructing a structural member.

Reinforced concrete structures or steel-framed reinforced concrete structures (hereinafter referred to as "reinforced concrete structures") bear tensile force with reinforcing bars and steel frames, and bear compressive forces with concrete and reinforcing bars and steel frames restrained by concrete. Since reinforced concrete structures were put into practical use, standards have been revised several times, and they have become highly safe and reliable, essentially not collapsing even in the face of earthquakes that exceed expectations in recent years. .

For existing reinforced concrete structures constructed according to the old standards before the revision, the ultimate deformation angle is limited according to the aspect ratio ho/D, axial force ratio η, etc., and the strength and toughness of the structural members are calculated. However, the seismic resistance of the entire structure in the event of an earthquake is evaluated, and if the seismic resistance is below a standard value, earthquake resistance reinforcement is performed to prevent collapse (Non-Patent Document 1 below).

One technique to further strengthen the strength of reinforced concrete structures is to mix synthetic fibers into fresh concrete to make it tougher. In addition, in reinforced concrete, there are technologies that use continuous fibers instead of reinforcing bars, and technologies that create materials with stress-strain relationships similar to reinforcing bars by coating high strength and high elongation carbon fibers with synthetic resin. There is.

For example, in Patent Document 1 listed below, a reinforcing material for a structural material is embedded in a structural material with low tensile strength (for example, concrete) to strengthen the tensile strength. It is disclosed that thin wires made of (polyamide fibers) are knitted in a braided manner. Further, Patent Document 2 below describes a concrete reinforcing material that has a core material made of a lightweight non-ferrous material (for example, synthetic resin, aluminum), and has a non-rust high performance fiber (for example, aramid fiber) on the outer periphery of the core material. ) is disclosed in which a fiber layer is formed.

Japanese Unexamined Patent Publication No. 1988-119853 Japanese Unexamined Patent Publication No. 199954/1983

On the other hand, the reinforcing bars included in reinforced concrete structures have a physical property weakness called buckling. Therefore, the current technical standards (non-patent document 2 above) require buckling prevention and shearing of axial (longitudinal) reinforcing bars (hereinafter referred to as "axial bars") in structural members such as reinforced concrete beams and columns. In order to improve strength, it is prescribed that shear reinforcing bars be placed at intervals of 100 mm to 150 mm. This spacing is very close to the thickness of the reinforcing bars. Furthermore, the same technical standards stipulate that the axial force ratio of columns be less than 0.35 and the aspect ratio be greater than 2.5, thereby preventing brittle collapse of structural members.

Generally, in reinforced concrete beams and columns, if there is a shortage of shear reinforcement, the axial reinforcement will undergo tensile yield due to repeated deformation, and the axial reinforcement that has yielded and stretched will buckle at the stage of transition from tension to compression. As a result, there is a risk that the axial reinforcement will destroy the concrete from the inside, lowering the axial strength and shear strength of the reinforced concrete structural member, and ultimately causing brittle collapse of the structural member.

The shear strength of structural members such as columns and beams can be addressed by increasing the compressive strength of concrete, but there is a limit to preventing buckling of axial reinforcements by strengthening concrete alone. Therefore, in order to supplement the physical properties of concrete, shear reinforcing bars have become an essential element in current reinforced concrete structures.

There is a technology that encapsulates continuous fibers in concrete instead of reinforcing bars that are encapsulated in concrete. However, no specific method other than applying tension to the continuous fibers has been proposed as a method for transmitting the stress borne by the continuous fibers to the concrete.

Additionally, continuous fibers themselves do not have the property of yielding at a stress above a certain level, unlike reinforcing bars. As a result, structural members such as beams and columns do not bend and yield and continue to resist external forces, resulting in so-called brittle collapse, where the structural members eventually collapse due to concrete failure or continuous fiber breakage. There is a danger of this happening. In addition, there is no method of calculating the ultimate strength of concrete containing continuous fibers, and strength calculations in the ultimate state of structural members, such as calculation of horizontal capacity under current standards and structural seismic resistance index under diagnostic standards, have not been proposed. There is also the issue that it cannot be applied.

In addition, there has been a proposal to encapsulate a composite material of continuous fibers that has a stress-strain relationship similar to that of reinforcing bars in concrete instead of reinforcing bars, but no specific method has been proposed.

As described above, in the conventional technology, it is possible to obtain a single reinforcing material that yields like reinforcing bars instead of reinforcing bars, or to embed materials other than reinforcing bars in concrete to reduce the brittleness of structural members. It is difficult to obtain a simple configuration that prevents collapse. When using reinforcing bars in reinforced concrete structures, there is a problem in that a large amount of shear reinforcing bars are required to prevent buckling.

The present invention has been made in view of the above circumstances, and provides a structural base material and a structural member that can construct a structural member having a simple configuration that does not require shear reinforcing bars inside a compressed material. , an object of the present invention is to provide a method for constructing a structure and a structural member.

In order to solve the above problems, the structural base material, structural member, structure, and method for constructing a structural member of the present invention employ the following means.
That is, the structural base material according to the present invention is a structural base material disposed inside a compressed material that bears the compressive force acting on the structural member, and is integrated with the compressed material when the compressed material is cured. a main body made of a material capable of bearing a compressive force; a tensile material disposed inside the main body from one end of the main body to the other end and having continuous fibers capable of bearing a tensile force; is wound around an outer circumferential surface, and a plurality of support parts are provided at intervals along the tension material inside the main body, and the tension material and the support parts are arranged so that the tension material and the support part It is fixed inside the main body part so as to transmit the stress generated in the main body part to the main body part.

According to this configuration, the compressive material in the structural member bears the compressive force acting on the structural member, and the structural base material is disposed inside the compressible material. The structural base material includes a main body part, a tensile material, and a plurality of supporting parts, and the main body part made of a material capable of bearing a compressive force is integrated with the compressive material when the compressive material of the structural member hardens, and the tensile material A tensile material having continuous fibers capable of bearing a force is disposed within the body portion from one end of the body portion to the other end, and the plurality of support portions are spaced apart from each other along the tensile material inside the body portion. provided. A tensile material is wound around the outer peripheral surface of the support portion. The tensile material and the support are secured within the body so as to transmit the stress generated in the tension material and the support to the body.

As a result, when a crack occurs in the main body, the tensile material and the supporting part are fixed inside the main body near the crack space, while the tensile material in the crack space stretches, and the direction of extension of the tensile material can freely change. or When a crack occurs in the main body part, a tensile force acts on the tensile material in the crack space, so the tensile material and the support part can prevent or delay the expansion of the crack. The tensile members and supports bear tensile forces corresponding to the forces borne by axial (longitudinal) reinforcing bars or shear reinforcement in conventional reinforced concrete-based structures, depending on the location of the crack. Therefore, the structural member can have the required shear strength without providing a member corresponding to the shear reinforcement.

In the above invention, the main body portion may have an external shape that can be integrated with the compressed material.

According to this configuration, the main body is integrated with the compression material due to the external shape of the main body, and the force transmitting the compression material is reliably transmitted to the structural base material.

In the above invention, the main body portion may have projections and depressions formed on its outer peripheral surface.

According to this configuration, the unevenness formed on the outer periphery of the main body allows the main body to be easily integrated with the compressed material.

In the above invention, the main body portion may have a three-dimensional shape by combining a plurality of rod-shaped members.

According to this configuration, since the main body has a three-dimensional shape by combining a plurality of rod-shaped members, the three-dimensional shape of the main body makes it easy to integrate the main body with the compression material.

In the above invention, the tensile material may be arranged inside the structural member in a direction oblique to a crack surface that occurs in the structural member.

According to this configuration, since the angle formed between the tensile material and the crack surface that occurs in the structural member is diagonal, the tensile material can absorb the tension borne by the axial (longitudinal) reinforcing bars in conventional reinforced concrete structures. In addition to bearing forces, the tension members tend to bear tensile forces comparable to the forces borne by shear reinforcements, not only in the general portion of the structural member but also in the hinge portions.

In the above invention, the supporting portion may have a through hole formed therein, and the tensile material may be wound around the outer peripheral surface while being inserted into the through hole.

According to this configuration, a through hole is formed in the support part, and the tension material is inserted into the through hole of the support part and wound around the outer peripheral surface, so that the tension material and the support part are difficult to shift from each other. , the support is securely installed in the tensile material.

In the above invention, the tensile material may be wound a plurality of times on the outer circumferential surface of the support section provided at the end of the tensile material.

According to this configuration, since the tensile material is wound around the outer circumferential surface of the support portion multiple times at the end portion of the tensile material, the tensile material does not easily come off from the support portion at the end portion of the tensile material.

In the above invention, the support portion may be made of a material that yields when a tensile force of a predetermined value or more is applied to the tensile material.

According to this configuration, when a tensile force of more than a predetermined value is applied to the tensile member, the supporting part yields, so the stable structural member is not ended up with the breaking of the tensile member, but with the yielding of the supporting part. It can be done.

In the structural member according to the present invention, the above-described structural base material is disposed inside the compressed material.

A structure according to the present invention includes the above-described structural member.

The method for constructing a structural member according to the present invention includes the step of introducing the above-described structural base material into a mold together with the compressed material before hardening, stirring it, and integrating it with the compressed material.

According to this configuration, the structural member is constructed by putting the structural base material into the mold together with the compressed material before hardening, stirring it, and integrating it with the compressed material.

A method for constructing a structural member according to the present invention includes the steps of forming a three-dimensional member made of the above-mentioned structural base material and having a grid-like surface, and placing the three-dimensional member inside the compressed material before hardening and compressing the material. and a step of integrating the material with the material.

According to this configuration, a three-dimensional member is formed from the structural base material and has a grid-like surface, and the three-dimensional member is placed inside the compressed material before hardening and is integrated with the compressed material, thereby constructing the structural member. be done.

According to the present invention, it is possible to construct a structural member having a simple configuration that does not require shear reinforcing bars inside the compressed material.

FIG. 1 is a longitudinal sectional view showing a first example of a structural member according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view showing a second example of a structural member according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view showing a first example of a structural base material according to an embodiment of the present invention. It is a longitudinal cross-sectional view showing a second example of a structural base material according to an embodiment of the present invention. FIG. 3 is a perspective view showing a third example of a structural base material according to an embodiment of the present invention. It is a perspective view which shows the 4th Example of the structural base material based on one Embodiment of this invention. It is a front view which shows the 5th Example of the structural base material based on one Embodiment of this invention. FIG. 2 is an explanatory diagram showing a structural member according to an embodiment of the present invention. FIG. 2 is a perspective view of a tensile member and support portion of a structural substrate according to an embodiment of the present invention. FIG. 2 is a perspective view of a tensile member and support portion of a structural substrate according to an embodiment of the present invention. FIG. 2 is a longitudinal cross-sectional view showing the tensile member and support portion of the structural base material according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a crack in a structural member according to an embodiment of the present invention, and a schematic diagram of a resistance mechanism when a crack occurs in the structural member. FIG. 2 is an enlarged view showing a crack in a structural member according to an embodiment of the present invention, and a schematic diagram of a resistance mechanism when a crack occurs in the structural member. Test specimen No. 6 is a graph showing the relationship between the load per effective tensile material cross-sectional area and the interlayer deformation angle in No. 6. Test specimen No. FIG. 6 is a schematic diagram showing a cross section of No. 6, and shows the state of fracture of the tensile material and crushing of the support portion after the experiment. Test specimen No. 4.No. 5 and no. 6 is a graph showing the relationship between the load per effective tensile material cross-sectional area and the interlayer deformation angle in No. 6.

The structural member 10 according to one embodiment of the present invention is applied to, for example, structures such as buildings, civil engineering structures, and utility poles. The structural members 10 are, for example, beams, columns, walls, floors, foundations, piles, etc. that constitute a building. 1 and 2 illustrate the case where the structural member 10 mainly consists of columns, and below, the case where the structural member 10 is a column will be described.

The structural member 10 includes a compressed material 11 and a structural base material 1 disposed inside the compressed material 11, as shown in FIG. 1 or 2, for example. The compressive material 11 is a structural material that bears the compressive force acting on the structural member 10, and is, for example, concrete, cement, or the like. The compressed material 11 has a tensile rigidity so small that it can be ignored in structural design.

The structural base material 1 includes a main body portion 2, a tensile material 3, and a support portion 4, as shown in FIG. 3, for example. The structural base material 1 is arranged inside the compressed material 11 of the structural member 10. As shown in FIG. 1, the structural base material 1 is a member whose unit is several centimeters to several tens of centimeters, and is randomly arranged inside the compressed material 11.

Further, the structural base material 1 is not limited to the examples shown in FIGS. 1 and 3, but as shown in FIG. 2, the structural base material 1 is a continuous member having the same size as the structural member 10, and is It may be provided in the direction and have, for example, a grid shape. When the structural member 10 is a column with a rectangular cross section, the structural base material 1 having a lattice shape is installed on each of the four sides of the column. A compressed material 11 is filled in the hollow space between the main body parts 2 formed by the lattice shape. Further, one unit of the lattice shape is not limited to the quadrangle shown in FIG. 2, but may be a circle or a polygon of pentagon or more.

As shown in FIGS. 1 to 3, in order to prevent brittle fracture of the structural member 10, the structural base material 1 should be uniformly distributed inside the structural member 10, especially in the surface layer. The arrangement of the structural base material 1 is not limited to the examples shown in FIGS. 1 and 2, and the shape of the structural base material 1 is not limited to the example shown below.

In the structural member 10, shear reinforcing bars used in conventional reinforced concrete structures are not installed inside the compressed material 11. Here, the shear reinforcing bars are reinforcing bars whose length direction is arranged perpendicularly or obliquely to the axial direction of the structural member 10, or a structural member made of an alternative material.

The main body portion 2 of the structural base material 1 is made of a material that is integrated with the compressible material 11 of the structural member 10 when the compressed material 11 hardens, and is capable of bearing compressive force. The main body part 2 has a tensile member 3 and a support part 4 installed therein, and mainly bears compressive force and shearing force almost equally to the compressive member 11 in the structural member 10 . The main body part 2 is a material that becomes integrated with the tensile material 3 and the support part 4 by curing. The main body portion 2 is made of concrete, cement, etc., for example.

The main body portion 2 has an external shape that can be integrated with the compressed material 11. Thereby, the external shape of the main body part 2 allows the main body part 2 to be integrated with the compressed material 11, and the force transmitted through the compressed material 11 is reliably transmitted to the structural base material 1. For example, as shown in FIG. 3, the main body portion 2 has irregularities formed on its outer peripheral surface. FIG. 3 shows an example in which the main body portion 2 is one rod-shaped member, and concave portions and convex portions are alternately formed on the outer peripheral surface along the longitudinal direction. Further, the irregularities on the outer circumferential surface may be formed by a mold or the like, or may be formed by scraping the surface of the main body portion 2 after hardening so as to produce a rough surface. Thereby, the main body part 2 has a shape that is easily integrated with the compressed material 11. Moreover, as shown in FIG. 4, the main body part 2 is not limited to a linear rod-shaped member, but may have a curved shape. Due to these shapes, the main body portion 2 is easily integrated with the compressed material 11.

Further, the main body portion 2 of the structural base material 1 may have a three-dimensional shape by combining a plurality of rod-shaped members, as shown in FIGS. 5A to 5C. FIG. 5A shows an example in which rod-like members are combined to have a tetrapod shape, FIG. 5B shows an example in which rod-like members are combined to have a cubic shape, and FIG. 5C shows a rod-like member in a tetrapod shape. An example is shown in which are combined to have a lattice type. The cube-shaped or lattice-shaped main body portion 2 has a hollow space inside which is filled with the compressed material 11. According to the shapes shown in FIGS. 5A to 5C, the main body 2 and the compressed material 11 can be easily integrated even if the surface of the main body 2 has no irregularities. Further, the structural base material 1 is likely to be arranged inside the compressive material 11 so that the tensile material 3 is diagonal to the surface of the crack that occurs in the structural member 10.

The tensile material 3 is a linear member made of continuous fibers, for example, thread-like or string-like. The tensile material 3 is made of, for example, synthetic resin (eg, polyester) fibers or continuous fibers such as carbon fibers. The tension member 3 is arranged inside the main body 2 from one end of the main body 2 to the other end. A plurality of tension members 3 may be provided for one main body portion 2 . The tensile member 3 is capable of bearing a tensile force in the structural member 10, and mainly bears the tensile force among the forces acting on the structural member 10.

The tensile material 3 is a material whose bending rigidity, shear rigidity, and compressive rigidity are so small that they can be ignored in structural design, and which does not buckle even when subjected to compressive force while placed in the main body portion 2. Thereby, when a crack occurs, the tensile material 3 deforms freely within the crack space. That is, the tensile material 3 can be expanded within the crack space, and the direction of extension of the tensile material 3 can be freely changed. When a crack occurs in the main body part 2, the tensile material 3 and the support part 4 are fixed inside the main body part 2 in the vicinity of the crack space (approximately 50 mm to 100 mm from the crack surface). Therefore, when a crack occurs in the main body portion 2, the tensile force of the tensile member 3 is exerted as a resistance force against the expansion of the crack in the structural member 10.

As shown in FIG. 6, the tensile material 3 is arranged inside the structural member 10 so as to be diagonal to the surface of the crack that occurs in the structural member 10. Since the angle between the tensile member 3 and the crack surface that occurs in the structural member 10 is diagonal, the tensile member 3 bears the tensile force borne by the axial (longitudinal) reinforcing bars in conventional reinforced concrete structures. do. In addition, the tensile member 3 can easily bear a tensile force equivalent to the force borne by the shear reinforcement not only in the general portion of the structural member 10 but also in the hinge portion 10-1. The arrangement position of the tensile material 3 is determined by taking into consideration the tensile force acting on the structural member 10.

The tensile member 3 and the support part 4 bear a tensile force corresponding to the force borne by axial (longitudinal) reinforcing bars or shear reinforcing bars in conventional reinforced concrete structures, depending on the location where the crack occurs. Therefore, the structural member 10 can have the required shear strength without providing a member corresponding to a shear reinforcement. When the structural member 10 is a column, the tensile member 3 is damaged by the main body 2 near the end of the structural member 10 (so-called hinge portion 10-1) where cracks occur in a direction perpendicular to the axial direction (lengthwise direction). Resist tensile forces. The tensile material 3 resists the shearing force applied to the main body part 2 near the center (so-called general part) of the structural member 10 where cracks occur diagonally with respect to the axial direction (lengthwise direction).

As shown in FIG. 7, the tensile member 3 is provided with a plurality of support portions 4 spaced apart from each other along the tensile member 3. The support part 4 is installed inside the main body part 2 and transmits the stress generated in the tensile material 3 , that is, the tensile force, to the main body part 2 . The support portion 4 is, for example, a cylindrical member.

The support part 4 is a relatively rigid material with a larger Young's modulus than the tensile material 3. The support portion 4 is made of, for example, metal, and in the case of metal, it is made of, for example, iron, aluminum, stainless steel, or the like. The support portion 4 may be made of a material that undergoes deformation upon receiving a tensile force from the tensile material 3. Note that by using a material that yields the supporting portion 4 before the tensile material 3 breaks, the structural member 10 can be made to yield. When a tensile force of a predetermined value or more is applied to the tensile material 3, the supporting part 4 yields before the tensile material 3 breaks, so that the final result is not the breaking of the tensile material 3 but the yielding of the supporting part 4. Therefore, the structural member 10 is stabilized.

As shown in FIG. 7, the tensile material 3 is wound around the outer peripheral surface of each support portion 4. At this time, as shown in FIG. 8, the tension member 3 may be looped around the support portion 4 to tie it. Further, as shown in FIG. 9, the support portion 4 may have a through hole 4A formed therein. In this case, the tensile material 3 is inserted into the through hole 4A of the support portion 4 and wound around the outer peripheral surface. This makes it difficult for the tension member 3 and the support portion 4 to shift from each other, and the support portion 4 is reliably installed in the tension member 3. Instead of winding the tensile material 3 in the circumferential direction of the support part 4, a ring part for installing the support part 4 on the tension material 3 is formed in advance, and the support part 4 is inserted into the ring part. The support part 4 may be installed on the tensile member 3.

Furthermore, as shown in FIG. 7, the tensile material 3 may be wound a plurality of times (for example, five or more times) around the outer peripheral surface of the support part 4 provided at the end of the tensile material 3. Thereby, since the tensile material 3 is wound around the outer peripheral surface of the support part 4 multiple times at the end of the tensile material 3, the tensile material 3 is difficult to come off from the support part 4 at the end of the tensile material 3.

The tensile material 3 and the support section 4 are fixed inside the main body section 2 so as to transmit the stress generated in the tensile material 3 and the support section 4 to the main body section 2. By fixing the tensile member 3 and the support portion 4 inside the main body portion 2, the vicinity of the end portion (hinge portion 10-1) of the structural member 10 is moved in the axial direction (longitudinal direction) in conventional reinforced concrete structures. The tensile material 3 and the support portion 4 can reliably bear the tensile force equivalent to the force borne by the reinforcing bars (hereinafter referred to as "axial bars"). Further, near the center (general portion) of the structural member 10, the tension member 3 and the support portion 4 can reliably bear the tensile force equivalent to the force borne by the shear reinforcing bars in conventional reinforced concrete structures.

By adjusting the size of the support portions 4 and the spacing L between the plurality of support portions 4, the structural member 10 is set to collapse at the hinge portion 10-1. This prevents or delays the failure of the compressed material 11 in the general part of the structural member 10.

_By adjusting the size of the support part 4, the circumference Φ surrounding the support part 4 is set to be larger than _d _b π in the case of reinforcing bars. The tensile force borne by the directional reinforcement is guaranteed.

The tensile rigidity of the main body portion 2 is so small that it can be ignored in structural design. Since the main body part 2 is integrated with the compressed material 11 and disposed inside the compressed material 11, cracks that occur in the structural member 10 also occur in the main body part 2 of the structural base material 1. As a result, when a crack occurs in the main body portion 2, a crack space is formed, and a tensile force acts on the tensile material 3 within the crack space. Therefore, a tensile force acts on the tensile material 3 in the crack space, and it is possible to prevent or delay the expansion of the crack.

On the other hand, in order to fix the tensile material 3 in the main body part 2, unlike concrete or cement, if a material with tensile rigidity such as synthetic resin is used, the main body part 2 is less likely to crack due to tensile force. , it is not possible to apply the required tensile force to the tensile material 3 within the crack space. That is, a material in which continuous fibers are impregnated with synthetic resin (FRTP) acts in the same way as reinforcing bars inside compressed materials in reinforced concrete structures. As a result, the continuous fibers do not elongate within the crack space, and the elongation direction of the continuous fibers does not change freely. Therefore, FRTP can bear tensile force only in the length direction of the continuous fibers arranged within the synthetic resin. Therefore, since buckling cannot be prevented with FRTP alone, it is necessary to arrange shear reinforcing bars as in reinforced concrete structures.

In the structural base material 1, the tensile material 3 connects the supporting parts 4 at the shortest distance without slack between the adjacent supporting parts 4. As a result, when a force is applied to the tensile member 3 and the support portion 4 when a crack occurs, the tensile member 3 can instantly bear the tensile force and the tensile member 3 itself expands. If the material that bears the tensile force is not a linear member made of continuous fibers as in this embodiment, but a member made by connecting a plurality of rings or a net-like member made of synthetic fibers, sagging occurs when the main body portion 2 hardens. arise. Therefore, in the case of a ring connecting member or a net-like member, when a crack occurs, the crack is likely to expand because the tensile force cannot be applied until the slack of the member becomes zero.

Further, after the main body part 2 is hardened, a knot for tying the tensile material 3 may be provided inside the main body part 2 as a member for fixing the tensile material 3 instead of the support part 4 as in this embodiment. Conceivable. However, it is difficult to form a knot that will not be further tightened when a tensile force is applied to the tension member 3. Therefore, when a crack occurs, before a tensile force acts on the tensile material 3 and the tensile material 3 itself expands, the knots are squeezed and contract, and the length of the tensile material 3 between adjacent knots becomes longer. As a result, when a crack occurs, the tensile member 3 cannot bear the required tensile force, so the crack is likely to expand.

Hereinafter, a method for manufacturing the structural base material 1 and a method for constructing the structural member 10 according to the present embodiment will be described.
When producing the structural base material 1 according to this embodiment, first, a plurality of support parts 4 are installed at intervals from each other on the tensile material 3. When the support part 4 is a cylindrical member, as shown in FIG. 7, the tensile material 3 can be made not only to simply go around it, but also to connect the support part 4 with the tension material 3 as shown in FIG. good. In addition, as shown in FIG. 9, when a through hole 4A is formed in the support part 4, the tensile material 3 is inserted into the through hole 4A three times to form a figure 8 shape around the support part 4. It may be rotated.

Next, the tensile material 3 and the supporting portions 4 are arranged so that there is no slack in the tensile material 3 between adjacent supporting portions 4 and the tensile material 3 connects the supporting portions 4 at the shortest distance. Then, the material of the main body portion 2 before hardening is cast and placed around the tensile material 3 and the support portion 4 so as to be in close contact with each other without any gaps. Thereafter, when the material of the main body part 2 hardens, the tensile material 3 is provided inside the main body part 2 so that there is no slack between the adjacent support parts 4 and the support parts 4 are connected at the shortest distance. By manufacturing the structural base material 1 in a factory, quality can be easily ensured and the quality of the structural base material 1 can be improved. When creating the structural base material 1, while ensuring that the tensile material 3 is securely fixed to the support part 4 and keeping the slack of the tensile material 3 between adjacent support parts 4 to zero, It is necessary to control the point at which the material of the main body part 2 is poured.

When constructing the structural member 10 according to the present embodiment, as shown in FIGS. 1 and 3 to 6, there are two cases in which the structural base material 1 is a member whose unit is several centimeters to several tens of centimeters; As shown in FIG. 2, the construction method differs depending on whether the structural base material 1 is a continuous member having the same size as the structural member 10.

As shown in FIGS. 1 and 3 to 6, when the structural base material 1 is a small unit member whose unit is several cm to several tens of cm, first, the structural base material 1 of the small unit member is manufactured. be done. Further, a formwork for constructing structural members 10 such as columns, beams, walls, etc. is constructed.

Next, the produced plurality of structural base materials 1 are placed into the mold together with the uncured compressed material 11, and the structural base materials 1 and compressed material 11 are stirred within the mold. Thereby, the structural base material 1 is uniformly arranged inside the compressed material 11 of the structural member 10. When the compressed material 11 hardens, the structural base material 1 is integrated with the compressed material 11, and construction of the structural member 10 is completed.

As shown in FIG. 2, when the structural base material 1 is a three-dimensional member having a continuous shape and the same size as the structural member 10, first, the structural base material 1 of the three-dimensional member is produced. The structural base material 1 is, for example, a three-dimensional member having a grid-like surface. The structural base material 1, which is a three-dimensional member, has a shape corresponding to a structural member 10 such as a column, a beam, or a wall. Then, the structural base material 1 is transported and installed at the site where the structural member 10 is to be constructed. Further, formwork for constructing structural members 10 such as columns, beams, and walls is installed. At this time, the produced structural base material 1 is installed in the formwork.

Next, the compressed material 11 before hardening is put into the mold, and the compressed material 11 is stirred within the mold. When the compressed material 11 hardens, the three-dimensional structural base material 1 is integrated with the compressed material 11, and construction of the structural member 10 is completed.

Next, with reference to FIG. 7, the relationship between the tensile material 3 and the support portion 4 will be described.
As shown in FIG. 7, the tensile members 3 are continuously arranged inside the main body 2 along the axial direction (lengthwise direction) of the structural member 10. As shown in FIG. The support portion 4 is, for example, a cylindrical rod-shaped member, and the tensile material 3 is wound, for example, one turn in the circumferential direction of the support portion 4 . Since the tensile material 3 is continuous in the axial direction of the structural member 10, the support part 4 ensures the tensile force of the tensile material 3 and transmits the stress acting on the support part 4 to the main body part 2. Note that it is desirable that the tensile material 3 be bonded to the support portion 4 using an adhesive or the like. Thereby, loosening of the tensile material 3 is less likely to occur, and it becomes possible to take into account the frictional force between the tensile material 3 and the support section 4.

The stress τ _b generated in the main body portion 2 by the tensile force T is calculated using the following equation (1.1).

Here, τ _b : Stress generated in the main body part 2 (N/mm ² )
Φ: Perimeter surrounding the axial direction (length direction) of the support part 4 (=2(R+l)) (mm)
l _d :Fusing length (mm)
Note that the formula for calculating Φ is an example, and here, the circumferential length Φ at the longest portion when the tensile material 3 is cut along a plane perpendicular to the length direction is calculated.

In conventional reinforced concrete construction, in the calculation formula equivalent to equation (1.1), the circumferential length Φ of the axial reinforcement is set as Φ=d _b π (here d _b : axial reinforcement diameter), and the stress τ When _b is calculated, the circumferential length, anchorage length, etc. are designed so that the stress τ _b is less than the adhesive failure strength of concrete. Therefore, in this embodiment, by setting the circumferential length Φ surrounding the length direction (axial direction ₎ of the support part 4 to be larger than d _b π in the case of reinforcing bars, the diameter d _b The tensile force borne by the axial muscles is guaranteed.

Hereinafter, a method for calculating the resistance force (tensile force) of the tensile material 3 against cracks in each part of the structural member 10 will be explained, focusing on the relationship between the crack width of the structural member 10 and the strain of the tensile material 3 according to the present embodiment. .

10 and 11 show schematic diagrams of the resistance mechanism when a crack occurs in the structural member 10 according to the present embodiment. Cracks in the structural member 10 are broadly classified into two types. One is a so-called bending crack, such as the crack in the hinge portion 10-1 shown in FIG. 6, and the other is a so-called shear crack, such as the crack in the intermediate portion 10-2 shown in FIG. . Bending cracks and shear cracks differ in the final direction of crack expansion. The bending crack expands in the axial direction (lengthwise direction), as shown in FIG. Like bending cracks, shear cracks expand in the axial direction (lengthwise direction) in the initial stage, and in the final stage, they expand in the direction perpendicular to the axial direction (lengthwise direction) as shown in FIG.

10 and 11, θ is the angle between the tensile material 3 in the crack space and the inner surface 2a of the crack, α is the angle between the material axis direction of the tensile material 3 and the direction of crack expansion, and L is the distance between the supporting parts 4. be. Further, ΔC is the crack width, and ΔC _f is the elongation of the tensile material 3 over the distance L.

When the Young's modulus of the tensile material 3 is E _f and the breaking strain is ε _fu , the tensile force q _f of the tensile material 3 can be calculated using equation (1.2).

here,
E _f : Young's modulus of tensile material 3 (N/mm ² )
ε _f : Strain in tensile material 3 (dimensionless)
ε _fu : Fracture strain of tensile material 3 (dimensionless)
α: Angle between the length direction of the tensile material 3 and the direction of crack expansion in the crack space

At this time, the strain ε _f of the tensile material 3 across the crack is ΔC _f /L=(ΔC/sinθ)/L, and if ε _f <<ε _fu , the tensile force of the tensile material 3 at the crack width ΔC is It can be calculated using equation (1.3).

here,
ΔC: Crack width (mm)
θ: Angle between the tensile material 3 in the crack space and the inner surface 2a of the crack L: Distance between the supporting parts 4 inside the main body 2 and closest to the crack surface (mm)
Other symbols are the same as in the above formula

In the case of a so-called bending crack, such as the crack in the hinge part 10-1 shown in FIG. 6, in FIG. can be calculated.
In addition, in the case of a so-called shear crack, such as the crack in the intermediate portion 10-2 shown in FIG. 6, in FIG. (Tensile force of tensile material 3) can be calculated.
Here, the crack width ΔC is considered to be the maximum crack width allowed to satisfy the required strength, and may be individually specified.

In this embodiment, shear reinforcing bars in a reinforced concrete structure are not installed, but the tensile member 3 of the structural member 10 according to this embodiment has a member circumference in a plane perpendicular to the axial direction (length direction). Even at the stage where the crack remains unchanged (FIG. 10) and at the stage where the crack expands in the axial direction (lengthwise direction) (FIG. 11), the tensile material 3 exerts a resistance force proportional to the crack width ΔC. Therefore, this embodiment exhibits resistance not only to bending cracks but also to shear cracks.

The ultimate strength of the structural member 10 according to the present embodiment is determined by the shear force (=Q _mu ) at which the structural base material 1 disposed around the hinge portion 10-1 just reaches the yield strength or the tensile strength at break, and the intermediate This is the smaller of the shear forces (=Q _su ) that can be borne by the compressed material 11 and the structural base material 1 in the portion 10-2.

The shear force Q _mu (=2 M _u /h _o ) when the structural base material 1 around the hinge portion 10-1 just reaches the yield strength or the tensile strength at break is explained in, for example, Non-Patent Document 2. The reinforcing bar term (a _t σ _y ) in the first term of the ultimate bending strength Mu (Equation (1.3-11)) is expressed as the tensile force (= a It can also be calculated by replacing it with _f q _f ).

here,
N: Column axial force (kN)
a _t : Tensile axial muscle cross-sectional area (mm ² )
σ _y : Axial muscle yield strength (N/mm ² )
b: Column cross-sectional width (mm)
D: Column cross section (mm)
F _C : Compressive strength of concrete (N/mm ² )

Further, the shear force (=Q _su ) that can be borne by the compressed material 11 and the structural base material 1 in the intermediate portion 10-2 is, for example, the shear strength Q _C3 of the compressed material 11 and the stress of the structural base material 1 in the intermediate portion 10-2. It can also be calculated as the sum of tensile forces using equation (1.4).

here,
Q _C3 : Shear strength of compressed material 11 (N)
q _fc : tensile force per unit cross-sectional area of the tensile material 3 inside the structural base material 1 in the intermediate portion 10-2 (N/mm ² )
a _f : Cross-sectional area per piece of tensile material 3 inside structural base material 1 in intermediate portion 10-2 (mm ² )
n _C : Number of tensile members inside the structural base material 1 in the intermediate portion 10-2 that are effective for shear deformation (dimensionless)

By appropriately selecting and setting the arrangement of the structural base material 1, the configuration and physical properties of the tensile material 3 and the support part 4, etc. _, the ultimate shear strength (=Q _su ) can be set to be larger. Thereby, even if the structural member 10 is subjected to the designed shear force, it is possible to prevent the structural member 10 from ending up in shear (brittle fracture).

Furthermore, by setting the ultimate strength of the structural member 10 according to this embodiment to be greater than the expected horizontal force, the structural member 10 becomes a member that does not lead to brittle collapse.

For example, assuming that the tensile material 3 in the structural base material 1 is carbon fiber (Toray Co., Ltd. Torayca (registered trademark) yarn T300, Young's modulus Ef: 230,300 N/mm ² , breaking strain ε _fu : 1.5%), By setting the crack width ΔC to 0.2 mm and the distance L between the supporting parts 4 to 30 mm, it is possible to bear the same tensile force as the deformed reinforcing bar D22 having a yield strength σ _y =345 N/mm ² . At this time, the cross-sectional area of the tensile material 3 is one quarter of that of the deformed reinforcing bar. Although carbon fiber has a larger Young's modulus than reinforcing steel, it has a smaller breaking strain. By setting it to yield, it is possible to obtain a stable structural member 10 that does not end with the breaking of the tensile member 3 but ends with the yielding of the support portion 4.

Furthermore, by using a material such as polyester fiber, which has a small Young's modulus and a large breaking strain, as the tensile material 3 in the structural base material 1, it is possible to obtain a structure with higher toughness and fail-safe.

In this way, in the structure to which the structural member 10 according to the present embodiment is applied, unlike the case where shear reinforcing bars are installed in reinforced concrete structures, shear reinforcing bars are separately installed in the direction perpendicular to the axial direction (lengthwise direction). It can be set to have the same ultimate strength as a reinforced concrete structure without placing any materials. This not only significantly reduces the amount of materials that make up the structure, shortens construction time, reduces construction costs, and reduces environmental impact, but also contributes to reducing earthquake force and improving seismic resistance by reducing the weight of the structure. do.

Note that calculations can be made in the same way for structural members 10 such as beams, walls, floors, foundations, piles, and utility poles.

It is also possible to use different materials for the tension material 3 in the hinge part 10-1 and the intermediate part 10-2. Further, in the above embodiment, the assumed crack width was set to 0.2 mm, but the assumed crack width can be set depending on the use of the structure and the required performance. For example, if a certain degree of deformation is allowed, such as piloti columns in a parking lot on the first floor, the expected crack width may be set to 1 to 2 mm.

As described above, according to the present embodiment, the tensile material 3 is made of a material whose bending rigidity, shear rigidity, and compressive rigidity are so small that they can be ignored in structural design, and which does not buckle even when subjected to compressive force when placed in the main body 2. It is. Thereby, when a crack occurs, the tensile material 3 deforms freely within the crack space. That is, the tensile material 3 can be expanded within the crack space, and the direction of extension of the tensile material 3 can be freely changed. When a crack occurs in the main body part 2, the tensile material 3 and the support part 4 are fixed inside the main body part 2 in the vicinity of the crack space (approximately 50 mm to 100 mm from the crack surface). Therefore, when a crack occurs in the main body portion 2, the tensile force of the tensile member 3 is exerted as a resistance force against the expansion of the crack in the structural member 10.

Therefore, a structural base material 1 in which a tensile material 3 having a high tensile strength such as high-strength continuous fibers and a supporting portion 4 are combined is placed inside a compressive material 11, and a main body portion that bears compressive force like concrete. By integrating the tensile member 3 and the support part 4 with the tension member 2, it is possible to provide a structure that does not require shear reinforcing bars. Unlike the case where shear reinforcing bars are placed in reinforced concrete structures, the structural member 10 is made of materials perpendicular to the axial direction (lengthwise direction) to prevent buckling of axial bars and resist shear cracks. do not need. Therefore, the materials constituting the structure can be significantly reduced, and the weight of the structure can be reduced.

The construction of the structural member 10 is roughly divided into two steps: a step of producing the structural base material 1 and a step of integrating the structural base material 1 with the compressed material 11. Thereby, the structural base material 1 can be manufactured in a factory, and it becomes easy to ensure quality improvement of the structural base material 1. Then, at the site where the structural member 10 is constructed, the structural base material 1 manufactured at the factory only needs to be carried in and installed, and the work to manufacture the structural base material 1 on site is unnecessary. At the site, a formwork for constructing the structural member 10 is formed, and the compressed material 11 is cast into the formwork, so that the structural base material 1 and the compressed material 11 are integrated, and the structure of the structural member 10 is formed. Construction is complete.

Since the structural member 10 can omit most of the reinforcing steel work, it is possible to reduce the construction period and construction cost. Further, since the arrangement of the tensile members 3 does not require a specialized worker such as a reinforcing bar worker, it is easy to secure workers and the quality of the structure can be improved.

In addition, since the structural member 10 does not require shear reinforcing bars, most of the symptoms peculiar to reinforcing bars, such as neutralization of concrete, corrosion due to chloride ions, volumetric expansion, etc., can be eliminated. Furthermore, by eliminating the need for shear reinforcing bars, the heat bridge phenomenon caused by reinforcing bars during high-temperature periods is significantly improved, reducing the load on air conditioning equipment, suppressing the generation of greenhouse gases, and contributing to a reduction in environmental impact. do.

<Experiment example>
A model (test body) imitating the structural member 10 according to an embodiment of the present invention was created, and a horizontal loading experiment was conducted to verify the yield strength of the test body.
In the test specimen for this experiment, the part where the compressive material 11 and the main body part 2 according to the present embodiment are integrated is made of gypsum (compressive strength 2.6 N/mm ² ), and the tensile material 3 is made of polyester fiber. The body was shaped like a square prism. In the horizontal loading experiment, the upper end and lower end of the column of the test specimen were fixed, and only the horizontal displacement of the upper end of the column was unrestricted, and a horizontal load was applied to the upper end of the column.

Table 1 shows the specifications of the test specimen (test specimen No. 6) and the reinforcement specifications for theoretical value calculation, and Table 2 shows the tensile material specifications of the test specimen.

When considering bond failure, the theoretical value of the ultimate shear strength of a structural member using deformed reinforcing bars as the axial reinforcement (main reinforcement) is determined using the method of the toughness-guaranteed seismic design guideline without shear reinforcement (hoop reinforcement). Ta. When bond failure is not considered, the ultimate shear strength of the structural member can be calculated by the method of Non-Patent Document 1, and the value was 0.38 kN.

The theoretical value of the final bending shear force of a structural member using deformed reinforcing bars as axial reinforcement was determined by the method described in Non-Patent Document 1.

Both when considering adhesive failure and when adhesive failure is not considered, the ultimate shear strength Q _su is lower than the ultimate shear force Q _mu at bending, so structural members using deformed reinforcing bars without shear reinforcement are Theoretically, this will result in shear failure. For simplicity, the outermost diameter of the reinforcing bars was assumed to be the same as the nominal diameter.

Test specimen No. The cross-sectional area of the tensile member 3 in No. 6 is set to one half of that when a 1 mm deformed reinforcing bar is used as the axial reinforcement. Then, test specimen No. The distance LT between the adjacent support portions 4 is set so that the tensile material 3 of No. 6 exhibits the same tensile strength as a 1 mm deformed reinforcing bar in a cross-sectional area that is half of the deformed reinforcing bar. Further, the strain of the tensile material 3 was set to exceed the breaking strain, and the strain was set so that the final result was the breaking of the tensile material 3.

Test specimen No. 6, the tensile members 3 were arranged so that three tensile members 3 faced each side. Therefore, when a horizontal load is applied, the number of tension members 3 effective for tensile force is three. Test specimen No. In No. 6, beads made of acrylic resin (with through holes 4A) were selected as the support portion 4. As described in FIG. 9 of the above-described embodiment, the tensile material 3 is inserted into the through hole 4A, the tensile material 3 is wound around the outer peripheral surface of the support part 4, and the support provided at the end of the tensile material 3 is wound. In part 4, the tensile material 3 was wound twice around the outer peripheral surface.

A graph of the experimental results is shown in FIG. In addition, in the experiment, the cross-sectional area of the tensile material 3 was set to be one-half of the cross-sectional area of the reinforcing bar used for comparison, so the vertical axis in Fig. 12 is not the absolute value of the horizontal load, but the horizontal load as the tensile material. It is divided by the cross-sectional area to give the horizontal load per cross-sectional area of the tensile material (unit: kN/mm ² ).

As a result of the experiment, the specimen in this experiment exhibited bending deformation accompanied by bending cracks at the hinge part, rather than a bond splitting failure, which is the theoretical failure type when using deformed reinforcing bars without shear reinforcement. The tensile member 3 broke at a horizontal load of around 0.28 kN (around 0.47 kN/mm ² ), resulting in the final result.

From the above, it has been shown that it is possible to create a column that is prone to bending failure using only the longitudinal tensile members 3 and support portions 4 without installing shear reinforcing bars. Although axial force was not applied in this experiment, in the present invention, there is no element that destroys the compressed material 11 and the main body part 2 from the inside, such as conventional axial reinforcement, so even when axial force is applied, , as in the present experiment, it can be set so that the structural member 10 ends when the tensile member 3 yields or breaks.

In addition, in this experiment, as the horizontal load increased, as shown in Figure 13, the tension side support part 4 was crushed, so the two tension members 3 in the center resisted the horizontal load and eventually broke. Was. As a result, test specimen No. of this experiment. The proof stress of No. 6 did not reach the theoretical value of 0.4 kN of shear force at the end of bending when no shear failure occurs, but by setting the support part 4 so that it does not collapse, the tension side The three tension members 3 enable the structural member 10 to resist horizontal loads. Therefore, it can be said that a test specimen in which the supporting portion 4 does not collapse unless shear failure occurs can resist up to 0.42 kN, which is 1.5 times the final horizontal load obtained as the experimental value. This exceeds the theoretical value of 0.4 kN of shear force at the end of bending when deformed reinforcing bars are used without shear reinforcing bars.

In addition, test specimen No. of this experiment. In addition to No. 6, there was a test specimen in which a knot was provided in the tensile material instead of the support part 4 (test specimen No. 4), and a test specimen in which the tensile material was braided without providing the support part 4 (test specimen No. 4). A horizontal force experiment was conducted using No. 5). FIG. 14 shows these results for test specimen No. The results are shown in comparison with the results of 6. In all test specimens, the compression material was gypsum, and the tension material was arranged in the length direction of the specimen. In addition, test specimen No. Since the specimen in No. 5 was 15 mm square, the horizontal load was divided by the cross-sectional area of the tensile material and further divided by the cross-sectional area of the specimen, and the unit of the vertical axis in FIG. 14 is kN/mm ⁴ .

From Figure 14, this test specimen No. It can be seen that No. 6 significantly exceeds both rigidity and ultimate strength. In addition, test specimen No. No. 4 has low rigidity because the knot is tied and there is almost no strain in the tensile material. Furthermore, test specimen No. No. 5 has a braided shape, and since neither a knot nor a support portion 4 is present, no strain occurs in the tensile material, and the rigidity is low. Then, test specimen No. No. 5 ended with shear failure of the compressed material. From this, it can be seen that by providing the support portion 4 on the tensile material 3, the tensile material 3 arranged in the length direction of the structural member 10 effectively resists shear deformation, and the shear strength is improved.

Test specimen No. No. 4 was set as a tensile material with the same cross-sectional area as the deformed reinforcing bar, and eventually exhibited bending deformation and did not break even under a horizontal load of 0.6 kN. Therefore, test specimen No. 4 in which the support portion 4 was made of acrylic resin. 6, and test specimen No. 6 in which a knot was provided in place of the support portion 4. When the test specimen is made of a tensile material 3 that is set so that the supporting part 4 does not collapse and has the same area as the deformed reinforcing bar, instead of the specimen No. 4, the specimen No. 4 and test specimen no. It is considered that results exceeding 6 can be obtained.

1 : Structural base material 2 : Main body part 2a : Inner surface 3 : Tensile material 4 : Support part 4A : Through hole 10 : Structural member 10-1 : Hinge part 10-2 : Intermediate part 11 : Compression material

Claims

A structural base material disposed inside a compression material that bears the compressive force acting on the structural member,
a main body made of a material that is integrated with the compression material when the compression material hardens and is capable of bearing compression force;
a tensile material disposed inside the main body from one end to the other end of the main body and having continuous fibers capable of bearing tensile force;
a plurality of support parts around which the tensile material is wound around an outer circumferential surface and provided at intervals along the tensile material inside the main body;
Equipped with
The tensile material and the support are anchored within the body so as to transmit stresses generated in the tensile material and the support to the body.
The structural base material according to claim 1, wherein the main body portion has an external shape that can be integrated with the compressed material.
The structural base material according to claim 2, wherein the main body portion has irregularities formed on its outer peripheral surface.
The structural base material according to claim 2 or 3, wherein the main body portion has a three-dimensional shape formed by combining a plurality of rod-shaped members.
The structural base material according to claim 1, wherein the tensile material is arranged inside the structural member in a direction oblique to a crack surface that occurs in the structural member.
The structural base material according to claim 1, wherein the support portion has a through hole formed therein, and the tensile material is inserted into the through hole and wound around the outer peripheral surface.
The structural base material according to claim 1, wherein the tensile material is wound a plurality of times on the outer peripheral surface of the support section provided at the end of the tensile material.
The structural base material according to claim 1, wherein the support portion is made of a material that yields when a tensile force of a predetermined value or more is applied to the tensile material.
A structural member in which the structural base material according to claim 1 is disposed inside the compressed material.
A structure comprising the structural member according to claim 9.
A method for constructing a structural member, comprising the step of introducing the structural base material according to claim 1 into a mold together with the compressed material before hardening, stirring it, and integrating it with the compressed material.
forming a three-dimensional member having a lattice-like surface made of the structural base material according to claim 1;
arranging the three-dimensional member inside the compressed material before hardening to integrate it with the compressed material;
A method of constructing a structural member comprising: