Concrete structure

Abstract

To provide a concrete structure that can inhibit fretting fatigue of PC steel material.SOLUTION: A concrete structure comprises a concrete member, a duct buried in the aforesaid concrete member, multiple PC steel members that are arranged inside the aforesaid duct and tensioned, and a grout filled in the gap between the aforesaid duct and the aforesaid multiple PC steel members. Each of the aforesaid multiple PC steel members comprises twisted PC steel wires, a resin layer covering the outer peripheral surface of the aforesaid twisted PC steel wires, and a sheath covering the outside of the aforesaid resin layer.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to concrete structures.

Background Art

[0002] In concrete structures such as bridges, prestressed concrete (PC) members in which PC steel materials are arranged inside concrete members are used. The PC steel materials are fixed to the concrete members in a tensioned state by fixtures attached to the ends of the PC steel materials. The tension of the PC steel materials is maintained by the fixtures, and compressive stress is applied to the concrete members.

[0003] Patent Document 1 discloses a tension member for prestressed concrete. This tension member is such that an aggregate cable composed of a plurality of PC steel wires is covered with a sheath. A resin composition that cures after the tensioning of the aggregate cable is pre-filled between the aggregate cable and the sheath.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above-mentioned tension member is integrated with the concrete member by the resin composition curing after the tensioning of the aggregate cable. The resin composition has time-dependent curability, that is, it cures over time after the tensioning of the aggregate cable.

[0006] The above-mentioned aggregate cable is entirely covered with a sheath, and the outer peripheral surfaces of the individual PC steel wires are not covered. That is, each PC steel wire is a bare PC steel wire.

[0007] When the assembled cable is tensioned, the plurality of PC steel wires are tightened toward the center of the assembled cable. Therefore, the PC steel wires arranged outside the center PC steel wire contact the center PC steel wire, and lateral pressure acts on the PC steel wire arranged at the center of the assembled cable. Since each of the PC steel wires is a bare PC steel wire, the PC steel wires directly contact each other. At the location where the lateral pressure acts, fretting occurs on the PC steel wires due to the rubbing between the PC steel wires. Therefore, there is a risk that the PC steel wires will break due to fretting fatigue.

[0008] In particular, for an assembled cable arranged in a bent state, in addition to the above-mentioned lateral pressure, bending stress is added. Therefore, fretting fatigue is more likely to occur in the PC steel wires, and breakage of the PC steel wires is more likely to occur.

[0009] Also, even if the above resin composition is filled between the PC steel wires, this resin composition cannot prevent the fretting of the PC steel wires. This resin composition is in an uncured state when the assembled cable is tensioned and is flowed by the above-mentioned lateral pressure. Therefore, the resin composition cannot prevent the contact between the PC steel wires and does not function as a buffer material between the PC steel wires.

[0010] One of the purposes of the present disclosure is to provide a concrete structure capable of suppressing fretting fatigue of PC steel materials.

Means for Solving the Problems

[0011] The concrete structure of the present disclosure includes a concrete member, a duct embedded inside the concrete member, a plurality of PC steel materials arranged in a tensioned state inside the duct, and grout filled in the gap between the duct and the plurality of PC steel materials. Each of the plurality of PC steel materials includes a PC steel wire, a resin layer covering the outer peripheral surface of the PC steel wire, and a sheath covering the outside of the resin layer.

Effects of the Invention

[0012] The concrete structure of the present disclosure can suppress the flexural fatigue of PC steel materials.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0014] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described.

[0015] (1) The concrete structure of the present disclosure includes a concrete member, a duct embedded inside the concrete member, a plurality of PC steel materials arranged in a tensioned state inside the duct, and grout filled in the gap between the duct and the plurality of PC steel materials. Each of the plurality of PC steel materials includes a PC steel wire, a resin layer covering the outer peripheral surface of the PC steel wire, and a sheath covering the outside of the resin layer.

[0016] In the concrete structure of the above (1), in each of the plurality of PC steel materials, the outside of the PC steel wire is covered by the sheath. The sheath prevents the PC steel wires constituting adjacent PC steel materials from directly contacting each other. By functioning as a buffer material between the PC steel wires, the sheath suppresses the fretting fatigue of the PC steel materials. Further, in each PC steel material, the PC steel wire is protected against corrosion by the resin layer and the sheath.

[0017] When the resin layer cures after the PC steel wire is tensioned, the PC steel wire is integrated with the sheath. That is, the PC steel wire, the resin layer, and the sheath constituting the PC steel material are integrated. When the grout cures, the sheath and the duct are integrated. By these integrations, the plurality of PC steel materials and the grout inside the duct and the concrete member outside the duct are integrated, so that the plurality of PC steel materials and the concrete member are integrated.

[0018] (2) In the concrete structure of the above (1), the plurality of PC steel materials may be arranged in parallel with each other.

[0019] Compared with a plurality of randomly arranged PC steel materials, the laterally applied pressure described above is less likely to occur when the plurality of parallelly arranged PC steel materials are tensioned. If the laterally applied pressure is less likely to occur, fretting is less likely to occur in the PC steel wire, and the fretting fatigue of the PC steel material can be further suppressed.

[0020] (3) In the concrete structure of the above (1) or (2), the number of the plurality of PC steel materials may be 2 or more and 37 or less.

[0021] If the number of PC steel materials is 2 or more and 37 or less, it is easy to insert a plurality of PC steel materials into the duct.

[0022] (4) In any of the concrete structures described in (1) to (3) above, the outer diameter of the PC steel wire may be 12 mm or more and 32 mm or less.

[0023] If the outer diameter of the PC steel wire is 12 mm or more and 32 mm or less, it is easy to miniaturize the PC steel material. If the PC steel material is small, it is easy to insert the PC steel material into the duct.

[0024] (5) In any of the concrete structures described in (1) to (4) above, the resin layer may be made of an epoxy resin.

[0025] The resin layer made of an epoxy resin can be adjusted to cure after the PC steel material is tensioned.

[0026] (6) In any of the concrete structures described in (1) to (5) above, the sheath may be made of a polyethylene resin.

[0027] The sheath made of a polyethylene resin has high durability.

[0028] (7) In any of the concrete structures described in (1) to (6) above, the duct may be made of a polyethylene resin.

[0029] The duct made of a polyethylene resin has high durability.

[0030] [Details of Embodiments of the Present Disclosure] Specific examples of the concrete structure according to the embodiment will be described below. The same reference numerals in the drawings indicate the same named objects. The sizes of the members shown in each drawing are expressed for the purpose of clarifying the explanation and do not necessarily represent actual dimensional relationships. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0031] As shown in FIG. 1, the concrete structure according to the embodiment includes a concrete member 100, a plurality of PC steel materials 1, a duct 3, and a grout 4. In this example, the concrete structure is a bridge. The concrete member 100 is a floor slab in the bridge. The floor slab is installed on the main girder spanned between the piers. The X direction in the figure is the direction along the length of the concrete member 100, which is the direction along the length of the bridge in this example. The Y direction is the direction along the width of the concrete member 100, which is the direction along the width of the bridge in this example. The Z direction is the direction along the thickness of the concrete member 100, which is the direction along the height of the bridge in this example.

[0032] As shown in FIG. 2, the PC steel material 1 and the duct 3 are arranged along the X direction inside the concrete member 100. The PC steel material 1 is inserted into the duct 3 embedded inside the concrete member 100. The duct 3 is filled with the grout 4. The grout 4 is, for example, cement milk in which cement and water are mixed. In this example, as shown in FIG. 1, a plurality of ducts 3 are provided inside the concrete member 100, and a plurality of PC steel materials 1 are respectively inserted into each duct 3. In FIGS. 1 and 2, each duct 3 is shown as having one PC steel material 1 inserted therein, but actually, as shown in FIG. 3, a plurality of PC steel materials 1 are inserted into each duct 3. FIG. 2 shows a cross section parallel to the X-Z plane. FIG. 3 shows a cross section orthogonal to the X direction.

[0033] The concrete member 100 may be formed by assembling a formwork at the construction site and placing concrete, or it may be a precast member. A precast member is one in which concrete has been hardened in a factory in advance. Further, when the concrete member 100 is a large-sized one with a long length in the X direction, the concrete member 100 may be formed by placing the concrete in a divided manner, or may be one in which a plurality of precast members are connected. Divided placement means placing the concrete in a plurality of times. The concrete member 100 in this example is, as shown in FIG. 2, formed by being placed in a divided manner into a first section 101, a second section 102, and a third section 103.

[0034] (PC steel material) A plurality of PC steel materials 1 are arranged in a tensioned state within the duct 3. The plurality of PC steel materials 1 reinforce the concrete member 100 by applying a compressive stress to the concrete member 100. Each of the plurality of PC steel materials 1 includes, as shown in FIG. 4, a PC steel wire 10, a resin layer 12 covering the outer peripheral surface of the PC steel wire 10, and a sheath 14 covering the outside of the resin layer 12.

[0035] 〈PC steel wire〉 The PC steel wire 10 is composed of a plurality of steel wires 11 joined together. The number and diameter of the steel wires 11 constituting the PC steel wire 10 are appropriately set according to the tensile strength required for the PC steel wire 10. The tensile strength of the PC steel wire 10 is, for example, 1700 MPa or more, and further 2200 MPa or more. The more the number of the steel wires 11 or the larger the diameter of the steel wires 11, the thicker the PC steel wire 10 becomes and the larger the breaking load of the PC steel wire 10 becomes. The number of the steel wires 11 is, for example, 2 or more and 37 or less. If the number of the steel wires 11 is 37 or less, it is easy to suppress the outer diameter of the PC steel wire 10 from becoming too large. That is, it is easy to suppress the outer diameter of the PC steel material 1 from becoming too large. If the number of the steel wires 11 is 37 or less, the PC steel wire 10 is easy to bend. Therefore, it is easy to wind the PC steel material 1 around a drum or arrange the PC steel material 1 in a bent state. The number of the steel wires 11 may further be 2 or more and 20 or less. The diameter of the steel wire 11 is, for example, 2 mm or more and 6 mm or less. If the diameter of the steel wire 11 is 6 mm or less, the PC steel wire 10 is easy to bend. The diameter of the steel wire 11 may further be 2.5 mm or more and 5.5 mm or less. The diameters of the respective steel wires 11 constituting the PC steel wire 10 may be the same or different.

[0036] The outer diameter of the PC steel wire 10 is, for example, 12 mm or more and 32 mm or less. If the outer diameter of the PC steel wire 10 is 32 mm or less, it is easy to miniaturize the PC steel material 1. If the PC steel material 1 is small, it is easy to insert the PC steel material 1 into the duct 3. In addition, it is easy to wind the PC steel material 1 around a drum or arrange the PC steel material 1 in a bent state. The outer diameter of the PC steel wire 10 may further be 15 mm or more and 30 mm or less. The outer diameter of the PC steel wire 10 means the diameter of the circumscribed circle of the PC steel wire 10.

[0037] 〈Resin layer〉 The resin layer 12 covers the outer peripheral surface of the PC steel wire 10. The resin constituting the resin layer 12 is, for example, a moisture-curing type or heat-curing type resin that cures over time. The moisture-curing type resin or heat-curing type resin is, for example, the moisture-curing type epoxy resin or heat-curing type epoxy resin described in the Japan Society of Civil Engineers Standard "Quality Standard (Draft) for Epoxy Resin for Pregrout PC Steel Materials (JSCE-E 146-2010)" established in 2010. The resin layer 12 in this example is made of a moisture-curing type epoxy resin. This moisture-curing type epoxy resin has bisphenol A type epoxy resin as the main component and also contains, among other things, ketimine derivatives, calcium oxide, silica, etc. The moisture-curing type epoxy resin is, for example, the product named "Moisture-curing type pregrout resin (MC-MKII)" of Sumitomo Electric Industries, Ltd. The "II" in the product name means the Roman numeral "2". The resin layer 12 is in an uncured state before the tensioning of the PC steel material 1 and is cured after the tensioning of the PC steel material 1. When the resin layer 12 cures, the PC steel wire 10 and the resin layer 12 adhere, and the PC steel wire 10 and the sheath 14 are integrated. The resin layer 12 may be made of a heat-curing type epoxy resin. This heat-curing type epoxy resin contains bisphenol A type epoxy resin and methylene bisphenol type epoxy resin and also contains, among other things, dicyandiamide, talc, etc. The heat-curing type epoxy resin is, for example, the product named "Heat-curing type pregrout resin" of Sumitomo Electric Industries, Ltd. When the resin layer 12 is composed of a heat-curing type resin, the curing of the heat-curing type resin is promoted by the reaction heat generated during the hydration reaction when the concrete cures.

[0038] The resin layer 12 is formed, for example, by applying a resin that cures over time to the outer peripheral surface of the PC steel wire 10 or by extrusion coating with a resin that cures over time.

[0039] 〈Sheath〉 The sheath 14 covers the outside of the resin layer 12. The sheath 14 is made of resin. The sheath 14 in this example is made of polyethylene resin, specifically high-density polyethylene resin. The polyethylene sheath 14 has high durability. On the outer peripheral surface of the sheath 14, uneven portions are formed in which ridges and valleys are alternately arranged in the direction along the length of the PC steel material 1. When the resin layer 12 hardens, the uneven portions engage with the surrounding grout 4, whereby the PC steel material 1 is integrated with the grout 4.

[0040] The sheath 14 protects the PC steel wire 10. The sheath 14 prevents the PC steel wires 10 constituting the adjacent PC steel materials 1 from directly contacting each other. By functioning as a buffer material between the PC steel wires 10, the sheath 14 can avoid the PC steel wires 10 rubbing against each other. Therefore, the fretting fatigue of the PC steel material 1 can be suppressed. In addition, the sheath 14 has a function of preventing corrosion of the PC steel wire 10. The sheath 14 prevents excess moisture separated from the grout 4 from penetrating into the interior of the PC steel material 1.

[0041] The thickness of the sheath 14 is, for example, 2 mm or more and 5 mm or less. If the thickness of the sheath 14 is 2 mm or more, it is easy to protect the PC steel wire 10. If the thickness of the sheath 14 is 5 mm or less, it is easy to miniaturize the PC steel material 1. The thickness of the sheath 14 may further be 2.5 mm or more and 4.5 mm or less.

[0042] The sheath 14 is formed, for example, by extrusion coating resin on the outside of the resin layer 12. The sheath 14 in this example has two ribs 14r. The two ribs 14r are provided at point-symmetrical positions on the outer peripheral surface with respect to the center of the sheath 14.

[0043] 〈Number of PC steel materials〉 The number of PC steel bars 1 inserted into one duct 3 is appropriately set according to the strength level required for the concrete member 100. The combined strength level of all the PC steel bars 1 inserted into one duct 3 is, for example, 1860 MPa or more, further 2000 MPa or more, 2200 MPa or more. When the configurations of all the PC steel bars 1 are the same, the greater the number of PC steel bars 1, the higher the strength level. The number of PC steel bars 1 is, for example, 2 or more and 37 or less. If the number of PC steel bars 1 is 37 or less, it is easy to insert a plurality of PC steel bars 1 into the duct 3. The number of PC steel bars 1 may further be 2 or more and 20 or less. The configurations of the plurality of PC steel bars 1 may be the same or different from each other.

[0044] 〈Arrangement of PC Steel Bars〉 The plurality of PC steel bars 1 inserted into the duct 3 are arranged in parallel with each other. Being arranged in parallel means that the plurality of PC steel bars 1 are linearly arranged without being twisted. Compared with the plurality of twisted PC steel bars 1, the above-described lateral pressure is less likely to occur when the plurality of parallelly arranged PC steel bars 1 are tensioned. Therefore, it is less likely for fretting to occur in the PC steel wire 10, and the fretting fatigue of the PC steel bar 1 can be more suppressed.

[0045] (Duct) The duct 3 is embedded inside the concrete member 100. The duct 3 is a cylindrical member. A plurality of PC steel bars 1 are inserted into the duct 3. The shape of the duct 3 in this example is cylindrical.

[0046] The duct 3 is made of, for example, resin or metal. The duct 3 made of resin is lightweight and can reduce the weight of the concrete member 100. Further, the duct 3 made of resin does not rust, for example, by reacting with the moisture in the concrete or the moisture that has penetrated into the interior of the concrete member 100. The resin constituting the duct 3 is, for example, polyethylene resin or polyvinyl chloride resin. The duct 3 in this example is made of polyethylene resin, specifically high-density polyethylene resin. The duct 3 made of polyethylene has high durability. The duct 3 made of metal is less likely to be deformed or crushed than the duct 3 made of resin. The metal constituting the duct 3 is, for example, steel or stainless steel.

[0047] The porosity of the duct 3 is, for example, 30% or more and 60% or less. The porosity of the duct 3 means the ratio of the space in the internal space of the duct 3 where a plurality of PC steel materials 1 are not arranged in a cross section orthogonal to the X direction. That is, the porosity of the duct 3 is the ratio of the space filled with the grout 4 in the internal space of the duct 3. The porosity of the duct 3 is the ratio obtained by dividing the area obtained by subtracting the total cross-sectional area of the plurality of PC steel materials 1 from the cross-sectional area of the internal space of the duct 3 by the cross-sectional area of the internal space of the duct 3. If the porosity of the duct 3 is 30% or more, it is easy to fill the grout 4 with a plurality of PC steel materials 1 inserted into the duct 3. Further, if the porosity of the duct 3 is 30% or more, a sufficient amount of the grout 4 can be filled, and it is easy for the plurality of PC steel materials 1 and the duct 3 to be integrated by the grout 4. If the porosity of the duct 3 is 60% or less, it is not necessary to make the duct 3 excessively large or to excessively increase the amount of the grout 4 used. The porosity of the duct 3 may further be 45% or more and 55% or less.

[0048] The inner diameter of the duct 3 is appropriately set according to the number and diameter of the PC steel materials 1 inserted into the duct 3. The inner diameter of the duct 3 is, for example, 60 mm or more and 140 mm or less. If the inner diameter of the duct 3 is 60 mm or more, it is easy to insert a plurality of PC steel materials 1. If the inner diameter of the duct 3 is 140 mm or less, it is easy to miniaturize the duct 3. If the duct 3 is small, it is easy to install the duct 3 inside the concrete member 100. The inner diameter of the duct 3 may be, for example, 70 mm or more and 130 mm or less. The thickness of the duct 3 is appropriately set so that the duct 3 has a predetermined strength. The thickness of the duct 3 is, for example, 4 mm or more and 10 mm or less, and further 5 mm or more and 8 mm or less.

[0049] (Grout) The grout 4 is filled in the gap between the duct 3 and the plurality of PC steel materials 1. When the grout 4 hardens, the grout 4 adheres to the plurality of PC steel materials 1 and the duct 3, and the plurality of PC steel materials 1 and the duct 3 are integrated. When the plurality of PC steel materials 1 and the duct 3 are integrated, the plurality of PC steel materials 1 and the concrete member 100 are integrated. The load-bearing performance of the concrete member 100 in a state where the plurality of PC steel materials 1 and the concrete member 100 are integrated is improved. Therefore, the bearing strength of the concrete member 100 can be increased, and cracks are less likely to occur in the concrete member 100.

[0050] In this example, as shown in FIG. 3, two PC steel materials 1 are arranged in the duct 3. The number of steel wires 11 constituting the PC steel wire 10 is 19. The seven steel wires 11 arranged at the center of the PC steel wire 10 have the same diameter. The twelve steel wires 11 arranged on the outer periphery of the center part are arranged alternately around the axis of the PC steel wire 10 with those having a larger diameter and those having a smaller diameter than the steel wires 11 at the center part. The outer diameter of the PC steel wire 10 is 29 mm. The inner diameter of the duct 3 is 80 mm. The porosity of the duct 3 is 57.0%.

[0051] Figure 5 shows an example in which three PC steel materials 1 are arranged in the duct 3. In the example shown in Figure 5, the number of steel wires 11 constituting the PC steel wire 10 is 19. The seven steel wires 11 arranged at the center of the PC steel wire 10 have the same diameter. Among the twelve steel wires 11 arranged on the outer periphery of the center portion, those with a larger diameter and those with a smaller diameter than the steel wires 11 at the center portion are alternately arranged around the axis of the PC steel wire 10. The outer diameter of the PC steel wire 10 is 25.4 mm. The inner diameter of the duct 3 is 80 mm. The porosity of the duct 3 is 50.5%.

[0052] Figure 6 shows an example in which seven PC steel materials 1 are arranged in the duct 3. In the example shown in Figure 6, the number of steel wires 11 constituting the PC steel wire 10 is 7. The seven steel wires 11 have the same diameter. The outer diameter of the PC steel wire 10 is 15.2 mm. The inner diameter of the duct 3 is 80 mm. The porosity of the duct 3 is 56%.

[0053] Figure 7 shows an example in which nineteen PC steel materials 1 are arranged in the duct 3. In the example shown in Figure 7, the number of steel wires 11 constituting the PC steel wire 10 is 19. The seven steel wires 11 arranged at the center of the PC steel wire 10 have the same diameter. Among the twelve steel wires 11 arranged on the outer periphery of the center portion, those with a larger diameter and those with a smaller diameter than the steel wires 11 at the center portion are alternately arranged around the axis of the PC steel wire 10. The outer diameter of the PC steel wire 10 is 17.8 mm. The inner diameter of the duct 3 is 127 mm. The porosity of the duct 3 is 38%.

[0054] <Method for manufacturing a concrete member> The concrete member 100 can be manufactured by the manufacturing method shown below. The manufacturing method of the concrete member includes the following first step S1 to fifth step S5. Each step will be described in detail.

[0055] (First step) As shown in FIGS. 1 and 2, the first step S1 is a step of embedding the duct 3 inside the concrete member 100. The first step S1 is performed as follows. Assemble a formwork for pouring concrete. Place the duct 3 inside the formwork. After placing the duct 3, pour concrete into the formwork and place the concrete member 100. After the concrete hardens, remove the formwork.

[0056] As shown in FIG. 1, when providing a plurality of ducts 3 in the concrete member 100, the adjacent ducts 3 are arranged at an interval of a certain length or more. Since the ducts 3 are arranged at an interval, it is easy to fill the concrete between the ducts 3. In addition, since the ducts 3 are arranged at an interval, it is easy to secure a space into which the vibrator is inserted. The vibrator is a machine used when placing the concrete member 100. The vibrator is inserted into the concrete poured into the formwork and vibrates the unhardened concrete to remove unnecessary air bubbles from the concrete. The interval between the ducts 3 is, for example, 40 mm or more.

[0057] When the concrete member 100 is placed in sections, as shown in FIG. 2, the placing sections are divided into a first section 101, a second section 102, and a third section 103, and placed for each section. In the sectional placing, a duct 3 having a length extending over the total length of a plurality of placing sections is prepared. The duct 3 is placed inside the formwork, and the concrete is sequentially placed around the duct 3.

[0058] (Second step) The second step S2 is a step of arranging a plurality of PC steel materials 1 in the duct 3. In the second step S2, a plurality of PC steel materials 1 are inserted into the duct 3 provided in the concrete member 100. When inserting a plurality of PC steel materials 1 into the duct 3, the plurality of PC steel materials 1 may be inserted collectively, or the PC steel materials 1 may be inserted individually one by one. The insertion operation of the PC steel material 1 is performed, for example, by using a winch to draw the PC steel material 1 into the duct 3. When inserting a plurality of PC steel materials 1 into the duct 3 collectively, for example, the plurality of PC steel materials 1 are gathered by fixing a fitting to the end. A wire rope is attached to this fitting. By pulling this wire rope with a winch, the plurality of PC steel materials 1 are collectively drawn into the duct 3.

[0059] The plurality of PC steel materials 1 are arranged in parallel with each other in the duct 3. In this example, a plurality of PC steel materials 1 are inserted into the duct 3 collectively. By inserting a plurality of PC steel materials 1 collectively, the plurality of PC steel materials 1 can be inserted efficiently.

[0060] The PC steel material 1 has a length corresponding to the entire length of the concrete member 100. The plurality of PC steel materials 1 may be prepared according to the timing when the placement of the concrete member 100 is completed. Therefore, it is possible to avoid the resin layer 12 from curing before the tensioning of the PC steel material 1. For example, in the case of segmented placement, the period required for placing concrete from the first placement section to the final placement section is long. In this example, the duct 3 is embedded inside the concrete member 100 by placing concrete in all the placement sections. Thereafter, a plurality of PC steel materials 1 are inserted into the duct 3. With such a configuration, even if the period until the segmented placement of the concrete member 100 is completed is long, it is possible to tension the PC steel wire 10 by preparing the PC steel material 1 immediately before inserting the PC steel material 1 into the duct 3. On the other hand, in a configuration where the tension member is directly embedded in the concrete as in Patent Document 1, it is necessary to arrange the tension member in the formwork when placing the concrete member 100. In the tension member of Patent Document 1, the resin mixture hardens before the segmented placement of the concrete member 100 is completed, and the tension member cannot be tensioned.

[0061] (Step 3) The third step S3 is a step of filling the duct 3 with grout 4. The filling operation of the grout 4 is performed with a plurality of PC steel materials 1 inserted into the duct 3. By filling the duct 3 with the grout 4, the duct 3 and the plurality of PC steel materials 1 are integrated by the grout 4. That is, the concrete member 100 and the plurality of PC steel materials 1 are integrated. For the grout 4, for example, cement milk is used.

[0062] (Step 4) The fourth step S4 is a step of tensioning a plurality of PC steel materials 1 inserted into the duct 3. When tensioning the plurality of PC steel materials 1, the plurality of PC steel materials 1 may be tensioned simultaneously in a batch, or the PC steel materials 1 may be tensioned individually one by one. The tensioning operation of the PC steel material 1 is performed by using a jack to pull the PC steel wire 10. The tensioning operation of the PC steel material 1 is performed after the concrete has hardened.

[0063] The plurality of PC steel materials 1 are arranged in a tensioned state in the duct 3. In this example, the plurality of PC steel materials 1 are tensioned simultaneously in a batch. By tensioning the plurality of PC steel materials 1 in a batch, the working time can be shortened, and the plurality of PC steel materials 1 can be efficiently tensioned. In addition, by tensioning the plurality of PC steel materials 1 in a batch, the variation in the tension of each PC steel material 1 is less likely to occur.

[0064] The third step S3 of filling the grout 4 and the fourth step S4 of tensioning the PC steel material 1 may be interchanged in order. That is, the filling of the grout 4 may be performed before or after the tensioning of the PC steel material 1.

[0065] (Step 5) The fifth step S5 is a step of fixing a plurality of PC steel bars 1 in a tensioned state. When fixing the plurality of PC steel bars 1, the plurality of PC steel bars 1 may be fixed simultaneously in a batch, or the PC steel bars 1 may be fixed individually one by one. The fixing operation of the PC steel bars 1 uses a fixing tool to fix the tensioned PC steel bars 1 to the concrete member 100.

[0066] In this example, a plurality of PC steel bars 1 are fixed simultaneously in a batch by a fixing tool 5 described later. By fixing the plurality of PC steel bars 1 in a batch, the working time can be shortened, and the plurality of PC steel bars 1 can be fixed efficiently. Further, by performing the tensioning and fixing of the plurality of PC steel bars 1 simultaneously, it is possible to suppress uneven loads being applied to components such as the anchor disk 52.

[0067] (Fixing tool) With reference to FIGS. 8 to 10, an example of the fixing tool 5 will be described. For the configuration of each part of the PC steel bar 1, refer to FIG. 3 as necessary. The fixing tool 5 is a member that fixes a plurality of tensioned PC steel bars 1 to the concrete member 100. The fixing tool 5 includes a plurality of wedges 51, an anchor disk 52, and a cap 53. The fixing tool 5 is attached to the ends of the plurality of PC steel bars 1. The respective ends of the plurality of PC steel bars 1 protrude from the end face of the concrete member 100. FIG. 8 shows a cross-section parallel to the X-Y plane. FIG. 9 shows a cross-section parallel to the X-Z plane. In FIGS. 8 and 9, the hatching of the grout 4 and the concrete member 100 is omitted.

[0068] 〈Wedge〉 The wedge 51 individually grips the end portions of each of the plurality of PC steel materials 1. The number of wedges 51 is the same as the number of PC steel materials 1. The end portions of the PC steel materials 1 gripped by the wedges 51 have the resin layer 12 and the sheath 14 removed, and the PC steel wire 10 is exposed. The wedge 51 grips the outer peripheral surface of the PC steel wire 10 exposed from the resin layer 12 and the sheath 14. The shape of the wedge 51 is a frustum of a cone. Concavities and convexities for gripping the PC steel wire 10 are formed on the inner peripheral surface of the wedge 51. The wedge 51 is configured by combining a plurality of split pieces. In this example, the number of split pieces is 2. The material of the wedge 51 is, for example, steel.

[0069] 〈Anchor disk〉 The anchor disk 52 has a plurality of wedge holes 52a into which each of the plurality of wedges 51 is individually fitted. The wedge holes 52a penetrate the anchor disk 52. The wedge holes 52a are frustum-of-a-cone-shaped holes corresponding to the shape of the wedges 51. When the wedges 51 are fitted into the wedge holes 52a, the PC steel wire 10 is tightened by the wedges 51. The shape of the anchor disk 52 is a disk shape. The material of the anchor disk 52 is, for example, steel.

[0070] The anchor disk 52 is disposed on the end face of the concrete member 100. The anchor disk 52 is fixed to the first end face of the rib cast anchor 54 described later. The anchor disk 52 transmits the tension force of the tensioned PC steel material 1 to the rib cast anchor 54 as a compressive force.

[0071] 〈Rib cast anchor〉 The rib cast anchor 54 transmits the compressive force transmitted from the anchor disk 52 to the concrete member 100. The rib cast anchor 54 is formed in a frustum-of-a-cone-shaped cylindrical shape. The end portions of the plurality of PC steel materials 1 are inserted into the rib cast anchor 54. The material of the rib cast anchor 54 is, for example, steel or cast iron.

[0072] The rib cast anchor 54 is embedded in the end of the concrete member 100. The rib cast anchor 54 has a first end face to which the anchor disk 52 is fixed and a second end face to which a trampet sheath 55 described later is connected. The first end face of the rib cast anchor 54 is exposed from the end face of the concrete member 100 and is in contact with the peripheral edge of the anchor disk 52.

[0073] 〈Trampet Sheath〉 The trampet sheath 55 is disposed between the rib cast anchor 54 and the duct 3. The trampet sheath 55 is formed in a frustum-shaped cylindrical form. The trampet sheath 55 has a first end connected to the rib cast anchor 54 and a second end opposite to the first end. The inner diameter of the first end of the trampet sheath 55 is larger than the inner diameter of the second end. That is, the trampet sheath 55 flares from the second end toward the first end. The ends of a plurality of PC steel materials 1 are inserted into the trampet sheath 55. The plurality of PC steel materials 1 disposed in the trampet sheath 55 are arranged so as to spread from the second end toward the first end.

[0074] In this example, a joint sheath 56 for connecting between the trampet sheath 55 and the duct 3 is provided. The joint sheath 56 is formed in a cylindrical shape. The ends of a plurality of PC steel materials 1 drawn out from the end of the duct 3 are inserted into the joint sheath 56. The joint sheath 56 is connected so as to partially overlap the outer peripheral surface of the second end of the trampet sheath 55 and the outer peripheral surface of the end of the duct 3.

[0075] A grout injection port 57 shown in Fig. 9 is provided on the outer peripheral surface of the joint sheath 56. The grout injection port 57 is for injecting grout 4 into the joint sheath 56. A hose (not shown) is attached to the grout injection port 57. The hose extends from the grout injection port 57 to the outside of the concrete member 100.

[0076] The rib cast anchor 54, the trumpet sheath 55, and the joint sheath 56 are arranged in the formwork when placing the concrete member 100 and are embedded together with the duct 3 inside the concrete member 100.

[0077] 〈Cap〉 The cap 53 covers the anchor disk 52, a plurality of wedges 51 exposed from the anchor disk 52, and the respective end portions of a plurality of PC steel wires 10 protruding from the anchor disk 52. The inside of the cap 53 is filled with an anti-rust material 58. The anti-rust material 58 has a function of preventing corrosion of the anchor disk 52, each wedge 51, and the end portions of the PC steel wires 10 protruding from each wedge 51. The material of the cap 53 is, for example, steel. The anti-rust material 58 is composed of, for example, grout or resin. The resin constituting the anti-rust material 58 is, for example, an epoxy resin. In FIGS. 8 and 9, the hatching of the anti-rust material is omitted.

[0078] The PC steel wire 10 is covered with the resin layer 12 and the sheath 14 except inside the cap 53. The PC steel wire 10 inside the cap 53 is protected against corrosion by the anti-rust material 58. From the process of preparing the PC steel material 1 to the process of fixing the end portion of the PC steel material 1, the PC steel wire 10 is protected against corrosion without being exposed to the outside over its entire length.

[0079] The cap 53 of this example has an injection port 53a and a discharge port 53b for filling the anti-rust material 58 inside the cap 53 as shown in FIG. 9. The anti-rust material 58 is injected from the injection port 53a. When the surplus anti-rust material 58 is discharged from the discharge port 53b, the filling of the anti-rust material 58 into the cap 53 is completed.

[0080] The cap 53 of this example is fixed to the anchor disk 52 by bolts 59 shown in FIGS. 8 and 9. As shown in FIG. 10, bolt holes 59a into which the tip portions of the bolts 59 are screwed are formed in the anchor disk 52.

Explanation of Reference Numerals

[0081] 1 PC steel bar 10 PC steel wire 11 Steel wire 12 Resin layer 14 Sheath 14r Rib 3 Duct 4 Grout 5 Fastener 51 Wedge 52 Anchor disc 52a Wedge hole 53 Cap 53a Injection port 53b Drain port 54 Rib cast anchor 55 Trumpet sheath 56 Joint sheath 57 Grout injection port 58 Rust preventive 59 Bolt 59a Bolt hole 100 Concrete member 101 First section, 102 Second section, 103 Third section

Claims

1. A concrete member, a duct embedded inside the concrete member, a plurality of PC steel materials arranged in a tensioned state inside the duct, and grout filled in the gaps between the duct and the plurality of PC steel materials, wherein each of the plurality of PC steel materials comprises a PC steel wire, a resin layer covering the outer peripheral surface of the PC steel wire, and a sheath covering the outside of the resin layer, is a concrete structure.

2. The concrete structure according to claim 1, wherein the plurality of PC steel materials are arranged in parallel with each other.

3. The concrete structure according to claim 1 or claim 2, wherein the number of the plurality of PC steel materials is 2 or more and 37 or less.

4. The concrete structure according to claim 1 or claim 2, wherein the outer diameter of the PC steel wire is 12 mm or more and 32 mm or less.

5. The concrete structure according to claim 1 or claim 2, wherein the resin layer is made of an epoxy resin.

6. The concrete structure according to claim 1 or claim 2, wherein the sheath is made of a polyethylene resin.

7. The concrete structure according to claim 1 or claim 2, wherein the duct is made of a polyethylene resin.

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