Plate, tendon unit, method for manufacturing tendon unit, PC structure, and method for manufacturing PC structure

Abstract

To provide a plate capable of sufficiently spreading grout into gaps between a plurality of tendons in a PC structure.SOLUTION: A plate disposed to face rear end surfaces of crimping grips attached to a plurality of tendons bundled to form an inner layer and an outer layer includes a first surface, a second surface opposite to the first surface, an outer circumferential surface connecting the first surface and the second surface, a slit opening in the outer circumferential surface, and a plurality of recesses opening in the outer circumferential surface. The length of the slit is longer than the length of each recess, and the tendons forming the inner layer are fitted into the slit. The tendons forming the outer layer are fitted into the plurality of recesses.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a plate, a tendon unit, a method for manufacturing a tendon unit, a PC structure, and a method for manufacturing a PC structure. [Background technology]

[0002] Patent Document 1 discloses a structure in which prestress is introduced by tendons. The structure includes a foundation, a wall constructed on the foundation, and tendons that introduce prestress into the wall. The foundation has anchor holes. The wall is a concrete structure formed of concrete. The concrete structure has insertion holes that communicate with the anchor holes. Tendons are inserted into the insertion holes and the anchor holes. The lower ends of the tendons are fixed by a filler, such as grout, that is filled in the anchor holes. The upper ends of the tendons are fixed to the top surface of the concrete structure by anchors.

[0003] The lower end of the tendon in the anchoring hole is provided with a crimping grip that grips the outer periphery of the tendon. The crimping grip increases the contact area between the tendon unit including the crimping grip and the grout, thereby increasing the tendon's pull-out load. A tendon with a high pull-out load can be tensioned with a strong force, allowing for a higher prestress to be introduced into the concrete structure. As a result, the strength of the concrete structure is improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-19735 Summary of the Invention [Problem to be solved by the invention]

[0005] In a tendon unit containing multiple tendons, it is difficult to ensure that grout is distributed sufficiently throughout the gaps between the tendons in a PC structure, which can result in variations in the contact area between each tendon and the grout.

[0006] One object of the present disclosure is to provide a plate that can sufficiently fill the gaps between multiple tendons in a PC structure with grout. Another object of the present disclosure is to provide a tendon unit that can sufficiently fill the gaps between multiple tendons in a PC structure with grout, and a method for manufacturing such a tendon unit. Another object of the present disclosure is to provide a PC structure in which the gaps between multiple tendons are sufficiently filled with grout, and a method for manufacturing such a PC structure. [Means for solving the problem]

[0007] The plate of the present disclosure is arranged to face rear end surfaces of crimping grips attached to a plurality of tendons bundled together to form an inner layer and an outer layer, and includes a first surface, a second surface opposite to the first surface, an outer circumferential surface connecting the first surface and the second surface, a slit opening in the outer circumferential surface, and a plurality of recesses opening in the outer circumferential surface. The length of the slit is longer than the length of each recess, and tendons forming the inner layer are fitted into the slit. Tendons forming the outer layer are fitted into the plurality of recesses. [Effects of the Invention]

[0008] The plate of the present disclosure can allow grout to sufficiently spread into gaps between multiple tendons in a PC structure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view of a tank, which is a type of PC structure according to the first embodiment. [Figure 2] FIG. 2 is a partial cross-sectional view of the PC structure shown in FIG. [Figure 3]FIG. 3 is an enlarged cross-sectional view of a part of FIG. [Figure 4] FIG. 4 is an explanatory diagram illustrating the configuration of a plate according to the first embodiment and the arrangement of the plate relative to a plurality of tendons. [Figure 5] FIG. 5 is an explanatory diagram illustrating a procedure for arranging plates on a plurality of tendons. [Figure 6] FIG. 6 is an explanatory diagram following FIG. 5, illustrating the procedure for arranging plates on a plurality of tendons. [Figure 7] FIG. 7 is an explanatory diagram following FIG. 6, illustrating the procedure for arranging plates on a plurality of tendons. [Figure 8] FIG. 8 is an explanatory diagram illustrating the arrangement of the spacers and bands in the end grip group. [Figure 9] FIG. 9 is an explanatory diagram illustrating the manufacturing process of a PC structure. [Figure 10] FIG. 10 is an explanatory diagram illustrating the manufacturing process of the PC structure, following FIG. [Figure 11] FIG. 11 is an explanatory diagram illustrating the manufacturing process of a PC structure, following FIG. [Figure 12] FIG. 12 is an explanatory diagram illustrating the manufacturing process of a PC structure, following FIG. [Figure 13] FIG. 13 is an explanatory diagram illustrating an arrangement state of a plate set with respect to a plurality of tendons shown in the second embodiment. [Figure 14] FIG. 14 is an explanatory diagram illustrating the arrangement of plate sets relative to a plurality of tendons shown in the third embodiment. [Figure 15] FIG. 15 is a schematic side view of a tendon unit including an additional plate shown in the fourth embodiment. [Figure 16] FIG. 16 is an explanatory diagram illustrating the arrangement of additional plates in the end grip group shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0011] <1> A plate according to an embodiment of the present disclosure is arranged to face rear end surfaces of crimping grips attached to a plurality of tendons bundled together to form an inner layer and an outer layer, and includes a first surface, a second surface opposite to the first surface, an outer circumferential surface connecting the first surface and the second surface, a slit opening in the outer circumferential surface, and a plurality of recesses opening in the outer circumferential surface. The length of the slit is longer than the length of each recess, and tendons forming the inner layer are fitted into the slit. Tendons forming the outer layer are fitted into the plurality of recesses.

[0012] The plate is used in a PC structure including a concrete structure prestressed by multiple tendons. More specifically, the plate is placed at a position facing the rear end face of a crimping grip at the anchorage of multiple tendons in the PC structure. The crimping grip is placed at first ends of the multiple tendons. The rear end face of the crimping grip is the face of the crimping grip facing the second ends of the tendons. The second ends are the ends of the multiple tendons opposite the first ends.

[0013] The plate disposed on the rear end surface of the crimping grip has multiple recesses and at least one slit. One of the multiple tendons that forms the outer layer is fitted into each recess. One of the multiple tendons that forms the inner layer is fitted into the slit. These fittings maintain the multiple tendons spaced at a predetermined distance. As a result, grout can be sufficiently distributed in the gaps between the multiple tendons at the anchoring points of the multiple tendons in the PC structure.

[0014] Both the recesses and slits in the plate open to the outer peripheral surface of the plate. In other words, when fitting the tendons into the recesses or slits, the tendons can be approached from the outside of the outer peripheral surface of the plate. Therefore, the plate can be attached to the tendons even after the crimping grips have been attached to the tendons. Unlike the plate disclosed herein, if the portion of the plate into which the tendons are fitted is a through-hole, the plate must be fitted from the first end of the tendon before the crimping grips are attached. Furthermore, when attaching the crimping grips to the first end, the plate must be moved sufficiently away from the first end to sufficiently widen the spacing between the multiple tendons before attaching the crimping grips to each tendon. This operation is extremely cumbersome.

[0015] <2> the above <1> In the plate described above, the number of the slits may be plural, the slits may be arranged parallel to one another, and the slits may open in the same direction on the outer peripheral surface.

[0016] the above <2> According to the configuration of (1), even if the number of tendons forming the inner layer is large, the tendons can be spaced apart.

[0017] <3> the above <1> or <2> The plate described in item 1 may have a through hole penetrating in the thickness direction from the first surface toward the second surface.

[0018] The through holes can be used to screw the plate to another member. The other member could be another plate, for example. If the through holes are not screwed, they can be used as grout channels. In this case, the grout filling condition near the anchorage is improved. The through holes also contribute to reducing the weight of the plate. This lighter weight of the plate makes it easier to handle. The inner diameter of the through holes is smaller than the outer diameter of the tendon, for example.

[0019] <4> A tendon unit according to an embodiment of the present disclosure includes a plurality of tendons having first and second ends, and a fixing portion disposed at the first ends, the fixing portion including a cylindrical crimping grip that grips the outer periphery of each tendon, and a fixing portion disposed at a position facing a rear end surface of the crimping grip. <1> from <3> and the plate according to any one of the preceding items, wherein each tendon is individually disposed in one of the plurality of recesses or the slits.

[0020] In the tendon unit according to an embodiment of the present disclosure, the plate according to an embodiment of the present disclosure maintains the plurality of tendons spaced at a predetermined distance. When this tendon unit is used to construct a prestressed concrete structure, sufficient grout is distributed to the gaps between the plurality of tendons at the anchoring points of the tendon unit in the prestressed concrete structure, increasing the contact area between the anchoring points and the grout. Furthermore, the plate disposed on the rear end face of the crimping grip increases the contact area between the anchoring points and the grout. As a result, the plurality of tendons can be tensioned with a strong force, thereby increasing the prestress introduced into the concrete structure.

[0021] The plate is positioned facing the rear end face of the crimping grip, so when multiple tendons are tensioned in a PC structure, the plate acts as a stop for the crimping grip, preventing the tendons from being pulled out.

[0022] <5> the above <4> In the tendon unit described in 2. above, the number of plates may be plural, and the plural plates may include a plate set consisting of adjacent first and second plates. The first and second plates have substantially the same shape and size, and the slits in the first plate and the slits in the second plate open in different directions.

[0023] By arranging the first plate and the second plate so that the slits of the first plate and the second plate open in different directions, an independent space is formed surrounded by the slits of the first plate and the slits of the second plate, and a tendon is arranged in the independent space. The tendon arranged in the independent space is held in the independent space at a distance from the other tendons.

[0024] The first plate and the second plate may have the same configuration, which improves productivity of the first plate and the second plate.

[0025] <6> the above <5> In the tension member unit described above, the number of slits provided in the first plate and the second plate may be multiple, and different tension members may be arranged in each of multiple independent spaces surrounded by the slits provided in the first plate and the slits provided in the second plate.

[0026] The first plate and the second plate each have a plurality of slits, which form a plurality of independent spaces in the plate set, and this allows the spacing between the plurality of tendons forming the inner layer to be maintained even if the number of tendons forming the inner layer increases.

[0027] <7> the above <5> or <6> In the tendon unit described above, the first plate and the second plate may be connected to each other.

[0028] The connected first and second plates have excellent strength and can withstand the stress from the crimping grip when multiple tendons are tensioned. Also, by connecting the first and second plates, the first and second plates are less likely to shift relative to each other. If the first and second plates shift relative to each other, for example, the tendon may be pinched between the slits of the first plate and the slits of the second plate, which could cause damage to the tendon. Therefore, <7> According to the configuration of (1), damage to the tendons due to relative displacement between the first plate and the second plate is unlikely to occur.

[0029] <8> the above <4> from <7> The tendon unit may further include a plurality of grip groups arranged at different positions in a first direction from the first end portion to the second end portion, and each grip group may be formed by a plurality of the crimping grips arranged at the same position in the first direction. The plate is arranged in at least one of the plurality of grip groups.

[0030] By arranging multiple grip groups at different positions in the first direction, it is possible to distribute the locations on the PC structure where the pull-out load acts, allowing multiple tendons to be tensioned with a stronger force.

[0031] <9> the above <8> In the tension member unit described above, a plate-shaped spacer is provided in at least one of the plurality of grip groups, the spacer having a notch and a through hole, and each crimping grip of the grip group in which the spacer is provided may be held in the notch or the through hole.

[0032] If spacers are provided in the grip group, the plurality of crimping grips that form the grip group can be easily maintained at a predetermined distance.

[0033] <10> the above <8> or <9> The tendon unit described in may include a band that tightens the grip group.

[0034] By fastening the grip group with the band, the spacing between the multiple crimping grips in the grip group is less likely to widen, making it easier to insert the tendon unit into the fixing hole.

[0035] <11> the above <4> from <10> In the tendon unit described in any one of the above, corners of the tip surface of the crimping grip may have a chamfered shape.

[0036] The chamfered corners on the tip surface of the crimping grip make it less likely for the crimping grip to get caught on the inner wall of the fixing hole when inserting the tendon unit into the fixing hole, making it easier to insert the tendon unit into the fixing hole.

[0037] <12> the above <4> from <11> In the tension member unit described in any one of the above, it may be provided with an additional plate arranged in a position facing the tip surface of the crimping grip, and a connecting shaft connecting the additional plate and the plate.

[0038] The additional plate increases the contact area between the anchoring portion of the tendon unit and the grout. The additional plate also reduces the variation in spacing between the tendons at the portion closer to the first end of the tendon than the crimping grip. The additional plate and the plate according to the embodiment are connected by a connecting shaft, so that the spacing between the tendons is maintained.

[0039] The additional plate may be a plate according to an embodiment of the present disclosure, or may be a plate of a different form from the plate. For example, a plate of a different form may have through holes through which the tendons are inserted. The additional plate with through holes may be applied to the end grip group. For grip groups other than the end grip group, the plate according to an embodiment of the present disclosure may be used as the additional plate.

[0040] <13> A method for manufacturing a tendon unit according to an embodiment of the present disclosure includes a step A of preparing a plurality of tendons having a first end and a second end, a step B of arranging a crimping grip on the first end of each tendon, and a step C of disposing a crimping grip on the first end of each tendon. <1> from <3> and a step D of attaching the plate to the side of the plurality of tendons at a position close to the rear end faces of the crimping grips of the plurality of tendons.

[0041] According to the manufacturing method of the tendon unit using the plate according to the embodiment of the present disclosure, the tendon unit according to the embodiment of the present disclosure can be manufactured.

[0042] When the crimping grips are placed on each tendon in step B, the first ends of the tendons are loosened into individual tendons. With the first ends of the tendons loosened, the plate according to the embodiment can be attached to the tendons from the side by approaching the tendons from the side. This makes it easy to attach the plate to the tendons.

[0043] <14> the above <13> In step D of the manufacturing method of the tension member unit described above, the tension member forming the inner layer may be placed in the slit of the plate, and then the tension member forming the outer layer may be placed in the recess of the plate.

[0044] Simply inserting a plate into the multiple tendons that have been loosened individually from the side will guide the tendons into the slits in the plate. At this time, the position of the plate on the multiple tendons is determined by placing the tendons that form the inner layer in the slit. From this state, the tendons that form the outer layer are placed in the recesses of the plate. Because the position of the plate on the multiple tendons is stable, it is easy to place the tendons in the recesses.

[0045] <15> The PC structure according to the embodiment of the present disclosure includes a foundation, a concrete structure constructed on the foundation, anchoring holes extending downward from the upper surface of the concrete structure, and the above-mentioned anchoring holes for applying prestress to the concrete structure. <4> from <12> The anchoring portion of the tendon unit is fixed to the bottom of the anchoring hole by solidified grout, the plurality of tendons of the tendon unit are arranged inside the anchoring hole in a tensioned state, and the second ends of the plurality of tendons are fixed to the upper surface.

[0046] In the PC structure according to the embodiment of the present disclosure, the anchoring portion is firmly fixed to the bottom of the anchoring hole by the plate according to the embodiment of the present disclosure, making it easy to increase the tension of the multiple tendons. Therefore, this PC structure can be a PC structure with higher prestress than conventional PC structures. PC structures with higher prestress have superior strength. After the second end is fixed on the top surface of the concrete structure, another concrete structure or the like may be placed further above the top surface.

[0047] <16> the above <15> In the PC structure described above, the bottom portion may have a portion whose inner diameter increases downward.

[0048] The inner diameter of the bottom of the anchoring hole increases downward, allowing the grout that solidifies inside the bottom to function as an anchor, making it easier to increase the tension of multiple tendons.

[0049] <17> the above <15> or <16> In the PC structure described in the above, the concrete structure may be a wall of a tank.

[0050] The tank is a tank that stores fuel such as liquefied natural gas. Extremely high strength is required for the walls of the tank that stores fuel. The PC structure of the present disclosure can meet such requirements.

[0051] <18> A method for manufacturing a PC structure according to an embodiment of the present disclosure is a method for manufacturing a PC structure in which a prestressed concrete structure is manufactured on a foundation, the method comprising the steps of: constructing the concrete structure so that a fixing hole extending downward from the upper surface of the concrete structure is formed; <4> from <12> The method includes a step β of inserting a tendon unit described in any one of the above into the fixing hole and positioning the fixing portion of the tendon unit at the bottom of the fixing hole, a step γ of filling the bottom with grout, a step δ of solidifying the grout, and a step ε of pulling the second ends of the plurality of tendons upward and fixing the second ends to the upper surface.

[0052] In the method for manufacturing a PC structure according to an embodiment of the present disclosure, step α is performed first and step ε is performed last. Step δ is performed after step γ. The specific order of the steps may be step α, step β, step γ, step δ, step ε, or may be step α, step γ, step β, step δ, step ε. According to the above method for manufacturing a PC structure, a PC structure according to an embodiment of the present disclosure can be manufactured.

[0053] [Details of the embodiments of the present disclosure] Specific examples of the plate, tendon unit, method for manufacturing a tendon unit, PC structure, and method for manufacturing a PC structure of the present disclosure will be described below with reference to the drawings. The same reference numerals in the figures indicate the same or equivalent parts. The dimensions of the components shown in each drawing are expressed for the purpose of clarity of explanation and do not necessarily represent the actual dimensions. Note that the present invention is not limited to these examples, but is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0054] <Embodiment 1> ≪PC structure≫ The PC structure 1 of this example shown in Figure 1 is a tank 100 that stores liquefied natural gas. The tank 100 comprises a disk-shaped base plate 102, a cylindrical wall 103 constructed on the base plate 102, and a dome-shaped roof 109 constructed on top of the wall 103. The base plate 102 and the wall 103 are made of concrete. The base plate 102 is the foundation 2 of the PC structure 1 of this example, and the wall 103 is the concrete structure 3 of the PC structure 1 of this example.

[0055] A plurality of tendon units 4 are arranged inside the wall 103. In Figure 1, the tendon units 4 are indicated by two-dot chain lines. The tendon units 4 are long bodies that apply prestress to the wall 103. The plurality of tendon units 4 are arranged at intervals along the circumferential direction of the wall 103. Each tendon unit 4 extends along the height of the wall 103. Each tendon unit 4 applies prestress to the wall 103 in the direction along the height of the wall 103, thereby improving the strength of the wall 103. Although not shown, tendon units are arranged along the circumference of the wall 103 in the wall 103. The circumferential tendon units apply prestress along the circumference of the wall 103, further improving the strength of the wall 103.

[0056] The arrangement of the tendon units 4 in the tank 100, which is a PC structure 1, will be described based on the cross-sectional views of Figures 2 and 3. Figure 2 is a cross-sectional view of the PC structure 1, cutting the portion where the tendon units 4 are arranged along a plane along the height of the wall 103. Figure 2 shows a simplified view of the tendon units 4. Figure 3 is an enlarged view of the vicinity of the lower end of the tendon unit 4 in Figure 2. Below, the arrangement of the tendon units 4 in the PC structure 1 will be described, with the base plate 102 serving as the foundation 2 and the wall 103 serving as the concrete structure 3.

[0057] As shown in FIG. 2 , the PC structure 1 includes a foundation 2, a concrete structure 3 constructed on the foundation 2, anchor holes 10 extending downward from the upper surface 3U of the concrete structure 3, and tendon units 4 for applying prestress to the concrete structure 3. In this example, the upper surface 3U is located at the top of the wall 103. Here, the upper surface 3U refers to the surface facing upward, not the top surface at the highest position of the concrete structure 3. For example, if the concrete structure 3 is formed in a stepped pattern, the upward-facing surfaces of each step are all the upper surfaces 3U. Alternatively, if the wall 103 is configured by stacking multiple concrete structures 3, the upper surface 3U may be located midway along the height of the wall 103. In this case, prestress can be partially introduced midway through the wall 103. In this example, the anchor holes 10 extend into the foundation 2. Unlike this example, the anchor holes 10 do not have to extend into the foundation 2. In other words, the bottoms 10B of the anchor holes 10 may be located inside the concrete structure 3. In this case, the foundation 2 does not have any holes that connect to the fixing holes 10, and the foundation 2 and the concrete structure 3 are connected by steel materials such as reinforcing bars.

[0058] [Foundation] The base 2 of the PC structure 1 is made of, for example, concrete. In this example, the base 2 includes a blind hole 2h having a bottom surface. The blind hole 2h forms a part of the fixing hole 10, more specifically, the bottom 10B of the fixing hole 10.

[0059] As shown in FIG. 3, the blind hole 2h in this example is formed by the internal space of a bottomed, cylindrical sheath 20 embedded in the foundation 2. The outer surface of the sheath 20 is provided with a plurality of ribs 20r to strengthen the engagement between the concrete forming the foundation 2 and the sheath 20. The material of the sheath 20 is not particularly limited, but a metal material is preferable. For example, the material of the sheath 20 is one or more types selected from the group consisting of carbon steel and cast iron. Examples of carbon steel include mechanical structural carbon steel such as S45C or general structural rolled steel such as SS400. Examples of cast iron include spheroidal graphite cast iron such as FCD450. For example, the sheath 20 may be a general structural carbon steel pipe such as STK400 or a mechanical structural carbon steel pipe such as STKM. The sheath 20 may also be a combination of two or more materials.

[0060] The blind hole 2h, i.e., the bottom 10B of the anchoring hole 10, has a portion whose inner diameter increases downward. In this example, the inner diameter of the bottom 10B increases downward and then remains constant. Solidified grout 7 is placed in the bottom 10B.

[0061] [Concrete structure] As shown in FIG. 2, the concrete structure 3 is made of concrete. The concrete structure 3 may be a single unit or a prefabricated structure made up of multiple stacked blocks. The concrete structure 3 may include reinforcing bars. The concrete structure 3 has an upper surface 3U facing upward and a lower surface 3D facing downward. The lower surface 3D faces the upper surface 2U of the foundation 2.

[0062] The concrete structure 3 has a through hole 3h that penetrates the concrete structure 3 from the upper surface 3U to the lower surface 3D. The through hole 3h is formed by a cylindrical sheath 30 embedded in the concrete structure 3. The material of the sheath 30 is not particularly limited and may be a metal material or a resin material. The metal sheath 30 is, for example, a thin steel plate molded into a roughly cylindrical shape or a general structural carbon steel pipe such as STK400. The resin sheath 30 is, for example, a resin material such as polyethylene molded into a roughly cylindrical shape. Ribs may be formed on the side of the sheath 30 to improve strength. The opening of the through hole 3h on the lower surface 3D is connected to a blind hole 2h in the foundation portion 2. The through hole 3h and the blind hole 2h form the above-mentioned fixing hole 10.

[0063] [Tension unit] The tendon unit 4 includes a plurality of tendons 40, each having a first end 40A and a second end 40B, and an anchoring portion 45 disposed at the first end 40A. In FIG. 2, only one tendon 40 is shown, and the anchoring portion 45 is simplified. The first end 40A of the tendon 40 is disposed vertically downward in the PC structure 1. The second end 40B is the end opposite the first end 40A and disposed vertically upward in the PC structure 1. In this example, the direction from the first end 40A toward the second end 40B is referred to as the first direction D1, and the direction from the second end 40B toward the first end 40A is referred to as the second direction D2. The anchoring portion 45 disposed at the first end 40A is located at the bottom 10B of the anchoring hole 10.

[0064] The plurality of tendons 40 will be described with reference to Figure 5. Figure 5 shows the plurality of tendons 40 cut along a plane perpendicular to the first direction D1. Figure 5 illustrates the plurality of tendons 40 with a space between adjacent tendons 40. The plurality of tendons 40 are bundled together to form an inner layer 40X and an outer layer 40Y. The plurality of tendons 40 may be arranged parallel to one another or may be twisted together. In this example, the plurality of tendons 40 are twisted together. In this example, there are 19 tendons 40. The number of tendons 40 included in the tendon unit 4 is not particularly limited.

[0065] The tendons 40 arranged inside the hexagon indicated by the two-dot chain line are the tendons 40 that form the inner layer 40X. The tendons 40 arranged outside the hexagon indicated by the two-dot chain line are the tendons 40 that form the outer layer 40Y. In other words, the tendons 40 that form the outer layer 40Y are the tendons 40 that are exposed to the outside among the multiple tendons 40 that are bundled together.

[0066] As shown in Fig. 3, the fixing portion 45 includes crimping grips 50 that grip the outer periphery of each tension member 40, and a plate 6 that is positioned facing the rear end surface 50B of the crimping grips 50. The crimping grips 50 have a known configuration. The crimping grips 50 are, for example, cylindrical bodies made of metal. In Fig. 3, to make the drawing easier to see, some of the crimping grips 50 and some of the tension members 40 are not shown. Additionally, tension members 40 that are located behind the tension members 40 shown in Fig. 3 are also not shown.

[0067] The crimping grip 50, which forms part of the fixing portion 45, is a member that increases the contact area between the fixing portion 45 and the grout 7. In particular, the rear end surface 50B of the crimping grip 50 functions as a retainer. The rear end surface 50B is a surface that faces the first direction D1 from the first end portion 40A toward the second end portion 40B.

[0068] The multiple crimping grips 50 provided in the tendon unit 4 in this example are divided into multiple grip groups 5 arranged at different positions in the first direction D1. In this example, there are three grip groups 5, but the number may be two, four, or more. Each grip group 5 is formed by multiple crimping grips 50 arranged at the same position in the first direction D1. By arranging the multiple grip groups 5 at different positions in the first direction D1, the areas on the PC structure 1 where the pull-out load acts can be dispersed. Therefore, the multiple tendons 40 can be tensioned with greater force. In this example, of the multiple grip groups 5, the grip group 5 located closest to the second direction D2 is called the end grip group 5E.

[0069] The tension member 40 is cut near the tip end surface 50F of the crimping grip 50 in each grip group 5. That is, the length of the tension member 40 differs among the multiple grip groups 5. The tip end surface 50F of the crimping grip 50 faces the second direction D2. The corners of the tip end surface 50F may be chamfered. This chamfered shape may be a C-chamfered shape or an R-chamfered shape.

[0070] Plate 6, which forms part of the fixing portion 45, is positioned facing the rear end surface 50B of the crimping grip 50. Plate 6 functions as a stop for the crimping grip 50 when the tendon 40 is tensioned. Plate 6 also maintains the state in which multiple tendons 40 are arranged at a predetermined interval in the fixing portion 45. Plate 6 is formed, for example, from metal. Here, in this example, plates 6 are arranged in all grip groups 5, but plates 6 may be arranged in only some of the grip groups 5. For example, plates 6 may be arranged only in the end grip group 5E.

[0071] The number of plates 6 arranged on the rear end surface 50B of the crimping grip 50 may be one or more. In this example, the plates 6 are used in pairs. A plate set 6S consisting of two plates 6, 6 is arranged in each of the multiple grip groups 5. The two plates 6, 6 forming the plate set 6S reinforce each other and are less likely to be damaged by pressure from the crimping grip 50. Unlike this example, the plate set 6S may be made up of three or more plates 6.

[0072] As shown in FIG. 4 , the plate 6 of this example is a plate-like member having a first surface 61, a second surface 62, and an outer peripheral surface 63. The second surface 62 is the surface opposite the first surface 61. The outer peripheral surface 63 is a peripheral surface connecting the first surface 61 and the second surface 62. The plate 6 further has a slit 65 opening in the outer peripheral surface 63, and a recess 66 opening in the outer peripheral surface 63 at a position different from the slit 65. The slit 65 is an elongated notch extending from the outer peripheral surface 63 toward the center of the plate 6. The recess 66 is an arc-shaped notch extending from the outer peripheral surface 63 toward the center of the plate 6.

[0073] The number of slits 65 is at least one. In this example, the number of slits 65 is three. The three slits 65 are arranged parallel to one another. The length of these slits 65 is longer than the length of the recesses 66. The length of the slit 65 is the length from the open end to the closed end of the plate 6. The open end of the slit 65 is the part formed by connecting the two edges that sandwich the opening of the slit 65 with a straight line. The length of the recess 66 is the length from the open end to the closed end of the recess 66. The open end of the recess 66 is the part formed by connecting the two edges that sandwich the opening of the recess 66 with a straight line. The tendons 40 that form the inner layer 40X are fitted into the slits 65, and the tendons 40 that form the outer layer 40Y are fitted into the recesses 66.

[0074] The width of the slit 65 perpendicular to the length of the slit 65 is the same as the diameter of the tendon 40 or slightly larger than the diameter of the tendon 40. The arc forming the recess 66 is an arc having the same radius as the radius of the tendon 40 or a slightly larger radius than the radius of the tendon 40. "Slightly" here means 5 millimeters or less.

[0075] The number of recesses 66 is determined according to the number of tendons 40 forming the outer layer 40Y. In this example, the number of recesses 66 is nine. The number of recesses 66 provided in one plate 6 is equal to or less than the number of tendons 40 forming the outer layer 40Y.

[0076] The plate 6 of this example further includes a plurality of through holes 67 that penetrate the plate 6 in the thickness direction. Some of the through holes 67 may have screws disposed therein to connect two plates 6. Other of the through holes 67 may have nothing disposed therein. The through holes 67 that have nothing disposed therein function as flow paths for grout 7 (e.g., FIG. 2).

[0077] In this example, the two plates 6 that make up the plate set 6S are identical. The right-hand plate 6 has the same shape as the left-hand plate 6 rotated 135° clockwise. In the following, when describing the arrangement of the plate set 6S relative to the multiple tendons 40, the left-hand plate 6 will be referred to as the first plate 6A and the right-hand plate 6 as the second plate 6B. The slit 65 and recess 66 of the first plate 6A will be referred to as the first slit 65A and the first recess 66A, respectively. The slit 65 and recess 66 of the second plate 6B will be referred to as the second slit 65B and the second recess 66B, respectively.

[0078] The lower part of FIG. 4 shows the first plate 6A and the second plate 6B assembled together. The first plate 6A is positioned further back than the second plate 6B. The first plate 6A and the second plate 6B are assembled in the orientation shown in the upper part of FIG. 4. Therefore, the first slit 65A and the second slit 65B open in different directions. Specifically, the first slit 65A opens to the right, and the second slit 65B opens to the lower left. In the plate set 6S consisting of the first plate 6A and the second plate 6B assembled in this orientation, multiple independent spaces 60 are formed, each surrounded by the first slit 65A and the second slit 65B. A tendon 40 forming the inner layer 40X is individually arranged in each independent space 60.

[0079] In a plate set 6S, which combines first plates 6A and second plates 6B having the same shape, some of the first recesses 66A and some of the second recesses 66B overlap. Specifically, when the plate set 6S is likened to a clock face, the first recesses 66A and the second recesses 66B overlap at the 1 o'clock, 5 o'clock, 9 o'clock, 10 o'clock, 11 o'clock, and 12 o'clock positions. At the 6 o'clock, 7 o'clock, and 8 o'clock positions, the first recesses 66A do not overlap the second recesses 66B, but overlap near the openings of the second slits 65B. At the 2 o'clock, 3 o'clock, and 4 o'clock positions, the second recesses 66B do not overlap the first recesses 66A, but overlap near the openings of the first slits 65A. Tendons 40 forming the outer layer 40Y are individually arranged in these first recesses 66A or second recesses 66B. In the portion where the first recessed portion 66A and the second recessed portion 66B overlap, one tendon 40 is disposed in the overlapping first recessed portion 66A and second recessed portion 66B.

[0080] Of the multiple through holes 67 in the first plate 6A and the multiple through holes 67 in the second plate 6B, screws may be placed in the corresponding through holes 67 to connect the first plate 6A and the second plate 6B. Some of the through holes 67 may not have screws. In this case, the through holes 67 function as flow paths for the grout 7 (FIG. 2) and improve the filling condition of the grout 7 near the anchorage portion 45.

[0081] When the first surface 61 is viewed in plan, the smallest circumscribing circle circumscribing the plate set 6S is smaller than the envelope circle of the multiple tendons 40 forming the outer layer 40Y. In other words, the first plate 6A and the second plate 6B forming the plate set 6S do not protrude outside the envelope circle. Therefore, when the tendon unit 4 is inserted into the fixing hole 10, the first plate 6A and the second plate 6B do not get caught on the inner peripheral surface of the fixing hole 10.

[0082] [Manufacturing method of tendon unit] The tendon unit 4 described above is manufactured in accordance with the following steps A to D. Step A: Preparing a plurality of tendons 40 having first ends 40A and second ends 40B. Step B: Placing a crimping grip 50 on each tendon 40 at the first end 40A. Step C: Prepare plate 6. Step D: The plate 6 is attached to the side of the plurality of tendons 40 at a position close to the rear end surface 50B of the crimping grip 50 on the plurality of tendons 40.

[0083] As already described, the multiple tendons 40 prepared in step A are bundled together to form an inner layer 40X and an outer layer 40Y. The multiple tendons 40 may be arranged parallel to one another or may be twisted together. Each tendon 40 is, for example, a PC steel rod or PC steel strand.

[0084] In step B, a crimping grip 50 is placed on each tendon 40 at the first end 40A. The crimping grip 50 is, for example, a metal cylindrical body. The crimping grip 50 is attached to the tendon 40 by, for example, passing the crimping grip 50 with the tendon 40 inserted therein through a die. By passing the crimping grip 50 through the die, the inner and outer diameters of the crimping grip 50 become smaller, and the crimping grip 50 grips the outer circumferential surface of the tendon 40.

[0085] In step C, for example, the plate 6 shown in Fig. 4 is prepared. Step C may be performed before step A, or after step A and before step B.

[0086] In step D, the plates 6 are attached to the plurality of tendons 40. Details of step D will be described with reference to Figs. 5 to 7. Figs. 5 to 7 explain the procedure for attaching the first plate 6A and the second plate 6B. The white arrows in Figs. 5 to 7 indicate the progress of the steps.

[0087] Figure 5 shows a cross section of the tendon 40 cut at the rear end surface 50B of the crimping grip 50. Therefore, the crimping grip 50 is not shown in Figure 5. In this example, there are 19 tendons 40. The number of tendons 40 that form the inner layer 40X, which is surrounded by a hexagon indicated by a two-dot chain line, is seven. The number of tendons 40 that form the outer layer 40Y, which is placed outside the inner layer 40X, is twelve. Because the crimping grip 50 is already attached to each tendon 40, some gaps are formed between the multiple tendons 40. From this state, as shown below the white arrow, some of the multiple tendons 40 that form the outer layer 40Y are opened in a direction away from the inner layer 40X.

[0088] As shown in Figure 6, the first plate 6A is inserted from a portion of the outer layer 40Y where some of the tendons 40 are open toward the inner layer 40X. At this time, the openings of the first slits 65A of the first plate 6A are made to face the inner layer 40X. In this way, simply by inserting the first plate 6A from the side of the tendons 40, the tendons 40 forming the inner layer 40X are fitted into each first slit 65A. In this example, three tendons 40 are placed in the central first slit 65A, and two tendons 40 are placed in each of the upper and lower first slits 65A.

[0089] Next, as shown in FIG. 7 , the tendons 40 forming the outer layer 40Y are spaced apart, and the second plate 6B is inserted toward the inner layer 40X so that the openings of the second slits 65B of the second plate 6B face the inner layer 40X. At this time, the second slits 65B are opened in a different direction from the first slits 65A. In this example, the first slit 65A opens toward the right in the drawing, and the second slit 65B opens toward the bottom left in the drawing. By inserting the second plate 6B in this manner, the first slits 65A and the second slits 65B intersect, forming multiple independent spaces 60 surrounded by the first slits 65A and the second slits 65B. Each tendon 40 forming the inner layer 40X is placed in each independent space 60.

[0090] Finally, each tendon 40 forming the outer layer 40Y is fitted into the second recess 66B of the second plate 6B or the first recess 66A of the first plate 6A. At this time, because the first plate 6A and the second plate 6B are fixed to the plurality of tendons 40 forming the inner layer 40X, it is easy to fit the tendons 40 forming the outer layer 40Y into the second recess 66B and the first recess 66A. Through the above-described steps, the plate set 6S is arranged on the plurality of tendons 40, as shown in the lower part of Figure 4.

[0091] As shown in Fig. 3, the tendon unit 4 of this example further includes a spacer 9 and a band 9B at the position of the end grip group 5E. As shown in Fig. 8, the spacer 9 is a plate-like member that maintains the spacing between the multiple crimping grips 50 that form the end grip group 5E. Fig. 8 is a view of the end grip group 5E of Fig. 3 as viewed in the first direction D1.

[0092] The spacer 9 has a through hole 90 and a notch 91. The number of through holes 90 is one or more, and in this example there is one through hole 90. A centrally located crimping grip 50 is inserted through the through hole 90. The number of notch 91 is one or more, and in this example there is a plurality of notch 91. Each crimping grip 50 surrounding the central tension member 40 is fitted into each notch 91. The spacer 9 maintains the spacing between the multiple crimping grips 50 that form the end grip group 5E. The material of the spacer 9 is not limited, and it is formed from, for example, metal or resin.

[0093] When the spacer 9 is viewed in plan, the smallest circumscribing circle circumscribing the spacer 9 is smaller than the envelope circle of the multiple crimping grips 50 that form the outer layer 40Y. In other words, the spacer 9 does not protrude outside the envelope circle. Therefore, when the tendon unit 4 is inserted into the fixing hole 10, the spacer 9 does not get caught on the inner circumferential surface of the fixing hole 10.

[0094] The band 9B is a member that tightens the outer periphery of the multiple crimping grips 50 arranged in the cutout portions 91. The band 9B presses the crimping grips 50 against the cutout portions 91. Therefore, the spacing between the multiple crimping grips 50 arranged in the cutout portions 91 does not widen.

[0095] The spacers 9 and bands 9B may be arranged at positions of the end grip groups 5E, as well as at positions of the grip groups 5 other than the end grip groups 5E. The spacers 9 and bands 9B may also be used independently. In other words, some of the multiple grip groups 5 may be grip groups 5 that include spacers 9 but no bands 9B, or grip groups 5 that include bands 9B but no spacers 9.

[0096] [grout] As shown in FIG. 2 , the anchoring portion 45 of the tendon unit 4 is fixed to the bottom 10B of the anchoring hole 10 by solidified grout 7. Each tendon 40 included in the tendon unit 4 is tensioned. The second end 40B of each tendon 40 is fixed to the upper surface 3U of the concrete structure 3 by a known anchoring device 8. The anchoring device 8 includes, for example, an anchor plate 80 with a through hole and a female cone 81 that supports the anchor plate 80. A wedge (not shown) that grips the outer periphery of the second end 40B of the tendon 40 is fitted into the wedge hole of the female cone 81, thereby fixing the second end 40B to the upper surface 3U. The material of the grout 7 is not particularly limited, but a non-shrink grout material is preferable. For example, the grout 7 includes one or more types selected from the group consisting of cement mortar, epoxy resin mortar, and water glass grout.

[0097] In the PC structure 1 of this example, multiple tendons 40 are held at a predetermined interval by plates 6, and grout 7 is sufficiently distributed in the gaps between adjacent tendons 40. Therefore, the anchoring portion 45 is firmly fixed to the bottom 10B of the anchoring hole 10, making it easy to increase the tension of the multiple tendons 40. This PC structure 1 can be a PC structure 1 with higher prestress than conventional PC structures. A PC structure 1 with high prestress has excellent strength.

[0098] <Manufacturing method for PC structures> The PC structure 1 of this example can be manufactured by the following steps α to ε. Step α: Construct the concrete structure 3 so that the fixing holes 10 extending downward from the upper surface 3U of the concrete structure 3 are formed. Step β: The tendon unit 4 is inserted into the fixing hole 10 , and the fixing portion 45 of the tendon unit 4 is positioned at the bottom 10B of the fixing hole 10 . Step γ: Fill the bottom 10B with grout 7. Step δ: The grout 7 is allowed to solidify. Step ε: The second ends 40B of the plurality of tendons 40 are pulled upward, and the second ends 40B are fixed to the upper surface 3U of the concrete structure 3. The order of the steps may be, for example, step α, step β, step γ, step δ, and step ε, or step α, step γ, step β, step δ, and step ε.

[0099] The manufacturing method of the PC structure 1 including the above steps α to ε will be described with reference to FIGS.

[0100] 9 shows the state after step α is completed. In step α of this example, a concrete structure 3 with a sheath 30 embedded therein is constructed on top of a foundation 2 with a sheath 20 embedded therein. At this time, a blind hole 2h formed by the internal space of the sheath 20 and a through hole 3h formed by the internal space of the sheath 30 are connected to each other to form a fixing hole 10.

[0101] In this example, two injection pipes 21, 22 and one overflow pipe 25 are buried in the foundation 2, each connected to a blind hole 2h. Injection pipe 21 is connected near the bottom surface of bottom portion 10B. Overflow pipe 25 is connected near the upper end of bottom portion 10B. Injection pipe 22 is connected to a position above overflow pipe 25 on bottom portion 10B.

[0102] Step β is performed using the tendon unit 4 in which the plate set 6S shown in Figure 4 is arranged. Specifically, the tendon unit 4 is inserted into the anchoring hole 10 from the top surface 3U (Figure 2) of the concrete structure 3, and the anchoring portion 45 of the tendon unit 4 is positioned at the bottom 10B, as shown in Figure 10. In the anchoring portion 45 of this example, the end grip group 5E is integrated by the spacer 9 and the band 9B, as shown in Figures 3 and 8. Therefore, when the tendon unit 4 is inserted into the anchoring hole 10, the anchoring portion 45 is less likely to get caught on the inner wall of the anchoring hole 10, and the tendon unit 4 can be inserted smoothly.

[0103] After the anchorage portion 45 is placed in the bottom portion 10B, step γ is performed. In this example, as shown in FIG. 11 , grout 7 is injected through the injection pipe 21. Once the grout 7 is discharged from the overflow pipe 25, the injection of the grout 7 is stopped. As a result, the bottom portion 10B of the anchorage hole 10 is sufficiently filled with grout 7. In this example, since the spacing between each tendon 40 is sufficiently maintained by the plate 6 in the anchorage portion 45, the contact area between the anchorage portion 45 and the grout 7 is larger than in a configuration without the plate 6.

[0104] Once the grout 7 has been sufficiently placed in the bottom portion 10B, the grout 7 is allowed to harden. The grout 7 in this example hardens over time.

[0105] Once the grout 7 has solidified, the second ends 40B of the multiple tendons 40 are pulled upward using a jack or the like, and the second ends 40B are fixed by the anchors 8. Fixing the tendons 40 with the anchors 8 maintains the tensioned state of the tendons 40, and prestress is applied to the concrete structure 3 along the height of the concrete structure 3. In this example, because the contact area between the anchors 45 and the grout 7 is very large, damage such as cracks is unlikely to occur in the grout 7 near the anchors 45 even if the tendons 40 are pulled with a force stronger than conventional.

[0106] Finally, as shown in Figure 12, grout 7 is filled into the inside of the fixing hole 10 from the injection pipe 22. The grout 7 is mainly filled inside the through hole 3h, and bonds the inner circumferential surface of the through hole 3h to the outer circumferential surface of the tendon 40. The grout 7 also has the effect of making the tendon 40 less susceptible to rust. Instead of grout 7, a rust inhibitor may be filled into the through hole 3h.

[0107] <Embodiment 2> In the second embodiment, a plate set 6S for maintaining the spacing between seven tendons 40 will be described with reference to Fig. 13. Fig. 13 can be viewed in the same way as Fig. 4 of the first embodiment.

[0108] The plate set 6S of this example includes a first plate 6A and a second plate 6B having the same configuration. The second plate 6B has the same shape as the first plate 6A rotated 180 degrees clockwise. The first plate 6A has one first slit 65A and five first recesses 66A. The second plate 6B has one second slit 65B and five second recesses 66B. The first plate 6A and the second plate 6B are combined so that the opening of the first slit 65A faces the opening of the second slit 65B. As a result, seven tendons 40 are held at predetermined intervals, as shown in the lower diagram of Figure 13.

[0109] <Embodiment 3> In the third embodiment, a plate set 6S for maintaining the spacing between the twelve tendons 40 will be described with reference to Fig. 14. Fig. 14 can be viewed in the same way as Fig. 4 of the first embodiment.

[0110] The plate set 6S of this example includes a first plate 6A and a second plate 6B having the same configuration. The second plate 6B has the same shape as the first plate 6A rotated 120 degrees counterclockwise. The first plate 6A has two first slits 65A and seven first recesses 66A. The second plate 6B has two second slits 65B and seven second recesses 66B. The first plate 6A and the second plate 6B are combined so that the first slits 65A and the second slits 65B intersect. As a result, as shown in the lower diagram of Figure 14, twelve tendons 40 are held at predetermined intervals.

[0111] <Embodiment 4> In a fourth embodiment, a tendon unit 4 including an additional plate 6C will be described with reference to Figs. 15 and 16. Fig. 15 is a schematic side view showing an enlarged view of the vicinity of an end grip group 5E in a PC structure 1 in which a tendon unit 4 including an additional plate 6C is arranged. Fig. 16 is a view of the end grip group 5E in Fig. 15 as viewed in a first direction D1.

[0112] As shown in Figure 15, the tendon unit 4 of this example includes, in addition to the plate 6, an additional plate 6C and a connecting shaft 6D. The additional plate 6C is arranged in a position facing the tip surface 50F of the crimping grip 50 in the end grip group 5E. The number of additional plates 6C may be one, or two or more. The connecting shaft 6D connects the additional plate 6C and the plate 6.

[0113] In this example, the additional plate 6C is a disk-shaped member. The additional plate 6C has a first through hole 601 through which the tendon 40 passes and a second through hole 602 through which the connecting shaft 6D passes. The inner diameter of the first through hole 601 is larger than the inner diameter of the second through hole 602. The additional plate 6C, which has the first through hole 601 and the second through hole 602, cannot be fitted into the tendon 40 from the side. However, in the end grip group 5E, the additional plate 6C can be placed on the tendon 40 from the first end 40A of the tendon 40. The additional plate 6C may further have a third through hole (not shown) that serves as a flow path for the grout 7.

[0114] Unlike this example, the additional plate 6C may be a plate having the same configuration as the plate 6, i.e., a plate that can be fitted into the tendon 40 from the side of the tendon 40. The additional plate 6C may also be arranged in other grip groups 5 other than the end grip group 5E. The additional plate 6C in the other grip groups 5 is a plate that can be fitted into the tendon 40 from the side of the tendon 40. Alternatively, the multiple crimping grips 50 in each grip group 5 may be fastened by a band 9B shown in FIG. 8.

[0115] The connecting shaft 6D of this example includes a threaded shaft 605 having a head 605H and a nut 606 screwed to the end of the threaded shaft 605 opposite the head 605H. The threaded shaft 605 passes through the through-hole 67 of the plate 6 and the second through-hole 602 of the additional plate 6C. The head 605H of the threaded shaft 605 abuts against a surface of the plate 6 facing the first direction D1. The nut 606 abuts against a surface of the additional plate 6C facing the second direction D2. The connecting shaft 6D tightens the plate 6 and the additional plate 6C between the head 605H and the nut 606 in a direction that brings them closer to each other. As a result, the crimp grip 50 is tightened by the plate 6 and the additional plate 6C, integrating these components. Note that the connecting shaft 6D may be oriented in the opposite direction to that of this example. In this case, the head 605H abuts against the additional plate 6C, and the nut 606 abuts against the plate 6.

[0116] According to the configuration of the fourth embodiment, the contact area between the anchoring portion 45 and the grout 7 is increased by the amount of the additional plate 6C compared to the configuration of the first embodiment. Therefore, the force tensioning the tendon 40 can be increased.

[0117] The additional plate 6C allows the spacing between the multiple tendons 40 on the second direction D2 side of the plate 6 to be maintained at a predetermined spacing. This prevents the spacing between the multiple tendons 40 from becoming larger or smaller when, for example, the tendon unit 4 is transported or inserted into the fixing hole 10.

[0118] By disposing the additional plate 6C in the end grip group 5E, the spacer 9 and the band 9B can be omitted. Of course, the additional plate 6C may be used in combination with the spacer 9 and the band 9B. [Explanation of symbols]

[0119] 1 PC structure 10 Fixing holes, 10B bottom 2 Foundation part 2h blind hole, 2U top 20 sheath, 20r rib 21, 22 Injection pipe, 25 Overflow pipe 3 Concrete Structures 3h through hole 3D bottom, 3U top 30 Sheath 4 Tendon Units 40 Tensile material 40A first end, 40B second end, 40X inner layer, 40Y outer layer 45 Fixing section 5 grip group, 5E end grip group 50 Crimping Grip, 50B Rear End Face, 50F Front End Face 6 plates 6A first plate, 6B second plate, 6S ​​plate set 60 Independent space, 61 First surface, 62 Second surface, 63 Outer surface 65 slit, 65A first slit, 65B second slit 66 recess, 66A first recess, 66B second recess 67 Through Hole 6C additional plate, 6D connecting shaft 601 first through hole, 602 second through hole 605 screw shaft, 605H head, 606 nut 7. Grout 8 Fixtures 80 Anchor plate, 81 Female cone 9 Spacers 90 through hole, 91 notch 9B Band 100 Tanks 102 foundation plate, 103 wall, 109 roof D1 First direction D2 Second direction

Claims

1. A plate is disposed at a position facing a rear end surface of a crimping grip attached to each of a plurality of tendons bundled together to form an inner layer and an outer layer, The front page and a second surface opposite the first surface; and an outer peripheral surface connecting the first surface and the second surface; a slit opening on the outer circumferential surface; a plurality of recesses opening to the outer circumferential surface, The length of the slit is longer than the length of each recess; Tendons forming the inner layer are fitted into the slits, Tendons forming the outer layer are fitted into the plurality of recesses. plate.

2. The number of the slits is plural, the plurality of slits are arranged parallel to one another, The plate according to claim 1 , wherein the plurality of slits on the outer peripheral surface are open in the same direction.

3. The plate according to claim 1 or 2, further comprising a through-hole penetrating in a thickness direction from the first surface toward the second surface.

4. a plurality of tendons having first and second ends; a fixing portion disposed at the first end portion, The fixing unit is a cylindrical crimping grip that grips the outer periphery of each tendon; the plate according to claim 1, which is disposed at a position facing the rear end surface of the crimping grip; A tendon unit, wherein each tendon is individually disposed in one of the plurality of recesses or the slits.

5. The number of the plates is plural, the plurality of plates includes a plate set consisting of adjacent first and second plates; the first plate and the second plate have substantially the same shape and size; The tendon unit according to claim 4 , wherein the slits provided in the first plate and the slits provided in the second plate open in different directions.

6. the number of the slits provided in the first plate and the second plate is plural, The tension member unit according to claim 5 , wherein different tension members are arranged in each of a plurality of independent spaces surrounded by the slits in the first plate and the slits in the second plate.

7. The tendon unit according to claim 5 , wherein the first plate and the second plate are connected to each other.

8. a plurality of grip groups arranged at different positions in a first direction from the first end toward the second end, Each grip group is formed by a plurality of the crimping grips arranged at the same position in the first direction, The tendon unit according to claim 4 , wherein the plate is disposed in at least one of the plurality of grip groups.

9. a plate-shaped spacer disposed in at least one of the plurality of grip groups; the spacer includes a notch and a through hole; The tendon unit according to claim 8 , wherein each crimping grip of the group of grips in which the spacer is arranged is held in the notch portion or the through hole.

10. The tendon unit of claim 8 , comprising a band for tightening the grips.

11. The tendon unit according to claim 4 , wherein corners of the tip surfaces of the crimping grips have a chamfered shape.

12. an additional plate disposed at a position facing the tip surface of the crimping grip; The tendon unit according to claim 4 , further comprising: a connecting shaft that connects the additional plate and the plate.

13. Step A of providing a plurality of tendons having first and second ends; Step B of placing a crimping grip on the first end of each tendon; a step C of preparing the plate according to claim 1 or claim 2; and a step D of attaching the plate to the sides of the plurality of tendons at positions adjacent to rear end surfaces of the crimping grips of the plurality of tendons. Method for manufacturing tendon units.

14. 14. The method for manufacturing a tendon unit according to claim 13, wherein in step D, the tendons forming the inner layer are placed in the slits of the plate, and then the tendons forming the outer layer are placed in the recesses of the plate.

15. The foundation and a concrete structure constructed on the foundation; a fixing hole extending downward from the upper surface of the concrete structure; and a tendon unit according to any one of claims 4 to 12 that applies prestress to the concrete structure, the anchoring portion of the tendon unit is fixed to the bottom of the anchoring hole by hardened grout; the plurality of tendons in the tendon unit are disposed in the fixing hole in a tensioned state; the second ends of the plurality of tendons are fixed to the upper surface; PC structure.

16. The PC structure according to claim 15, wherein the bottom portion has a portion whose inner diameter increases downward.

17. The PC structure according to claim 15, wherein the concrete structure is a wall of a tank.

18. A method for manufacturing a PC structure by which a prestressed concrete structure is manufactured on a foundation, comprising: a step α of constructing the concrete structure so that anchor holes extending downward from the upper surface of the concrete structure are formed; a step β of inserting the tendon unit according to any one of claims 4 to 12 into the fixing hole and arranging the fixing portion of the tendon unit at a bottom of the fixing hole; a step γ of filling the bottom with grout; a step δ of solidifying the grout; and a step ε of pulling the second ends of the plurality of tendons upward and fixing the second ends to the upper surface. Manufacturing method for PC structure.

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